<!--START complete-->
<!--START html--><!--START html5-->
<h2 class="no-num no-toc" id="contents">Table of contents</h2>
<!--toc-->
<hr>
<h2 id="introduction">Introduction</h2>
<h3>Background</h3>
<p><i>This section is non-normative.</i></p>
<p>The World Wide Web's markup language has always been HTML. HTML
was primarily designed as a language for semantically describing
scientific documents, although its general design and adaptations
over the years have enabled it to be used to describe a number of
other types of documents.</p>
<p>The main area that has not been adequately addressed by HTML is a
vague subject referred to as Web Applications. This specification
attempts to rectify this, while at the same time updating the HTML
specifications to address issues raised in the past few years.</p>
<h3>Audience</h3>
<p><i>This section is non-normative.</i></p>
<p>This specification is intended for authors of documents and
scripts that use the features defined in this specification<span
class="impl">, implementors of tools that operate on pages that use
the features defined in this specification, and individuals wishing
to establish the correctness of documents or implementations with
respect to the requirements of this specification</span>.</p>
<p>This document is probably not suited to readers who do not
already have at least a passing familiarity with Web technologies,
as in places it sacrifices clarity for precision, and brevity for
completeness. More approachable tutorials and authoring guides can
provide a gentler introduction to the topic.</p>
<p>In particular, familiarity with the basics of DOM Core and DOM
Events is necessary for a complete understanding of some of the more
technical parts of this specification. An understanding of Web IDL,
HTTP, XML, Unicode, character encodings, JavaScript, and CSS will
also be helpful in places but is not essential.</p>
<h3>Scope</h3>
<p><i>This section is non-normative.</i></p>
<p>This specification is limited to providing a semantic-level
markup language and associated semantic-level scripting APIs for
authoring accessible pages on the Web ranging from static documents
to dynamic applications.</p>
<p>The scope of this specification does not include providing
mechanisms for media-specific customization of presentation
(although default rendering rules for Web browsers are included at
the end of this specification, and several mechanisms for hooking
into CSS are provided as part of the language).</p>
<p>The scope of this specification is not to describe an entire
operating system. In particular, hardware configuration software,
image manipulation tools, and applications that users would be
expected to use with high-end workstations on a daily basis are out
of scope. In terms of applications, this specification is targeted
specifically at applications that would be expected to be used by
users on an occasional basis, or regularly but from disparate
locations, with low CPU requirements. For instance online purchasing
systems, searching systems, games (especially multiplayer online
games), public telephone books or address books, communications
software (e-mail clients, instant messaging clients, discussion
software), document editing software, etc.</p>
<h3>History</h3>
<p><i>This section is non-normative.</i></p>
<p>For its first five years (1990-1995), HTML went through a number
of revisions and experienced a number of extensions, primarily
hosted first at CERN, and then at the IETF.</p>
<p>With the creation of the W3C, HTML's development changed venue
again. A first abortive attempt at extending HTML in 1995 known as
HTML 3.0 then made way to a more pragmatic approach known as HTML
3.2, which was completed in 1997. HTML4 followed, reaching
completion in 1998.</p>
<p>At this time, the W3C membership decided to stop evolving HTML
and instead begin work on an XML-based equivalent, called
XHTML. This effort started with a reformulation of HTML4 in XML,
known as XHTML 1.0, which added no new features except the new
serialization, and which was completed in 2000. After XHTML 1.0, the
W3C's focus turned to making it easier for other working groups to
extend XHTML, under the banner of XHTML Modularization. In parallel
with this, the W3C also worked on a new language that was not
compatible with the earlier HTML and XHTML languages, calling it
XHTML2.</p>
<p>Around the time that HTML's evolution was stopped in 1998, parts
of the API for HTML developed by browser vendors were specified and
published under the name DOM Level 1 (in 1998) and DOM Level 2 Core
and DOM Level 2 HTML (starting in 2000 and culminating in
2003). These efforts then petered out, with some DOM Level 3
specifications published in 2004 but the working group being closed
before all the Level 3 drafts were completed.</p>
<p>In 2003, the publication of XForms, a technology which was
positioned as the next generation of Web forms, sparked a renewed
interest in evolving HTML itself, rather than finding replacements
for it. This interest was borne from the realization that XML's
deployment as a Web technology was limited to entirely new
technologies (like RSS and later Atom), rather than as a replacement
for existing deployed technologies (like HTML).</p>
<p>A proof of concept to show that it was possible to extend HTML4's
forms to provide many of the features that XForms 1.0 introduced,
without requiring browsers to implement rendering engines that were
incompatible with existing HTML Web pages, was the first result of
this renewed interest. At this early stage, while the draft was
already publicly available, and input was already being solicited
from all sources, the specification was only under Opera Software's
copyright.</p>
<p>The idea that HTML's evolution should be reopened was tested at a
W3C workshop in 2004, where some of the principles that underlie the
HTML5 work (described below), as well as the aforementioned early
draft proposal covering just forms-related features, were presented
to the W3C jointly by Mozilla and Opera. The proposal was rejected
on the grounds that the proposal conflicted with the previously
chosen direction for the Web's evolution; the W3C staff and
membership voted to continue developing XML-based replacements
instead.</p>
<p>Shortly thereafter, Apple, Mozilla, and Opera jointly announced
their intent to continue working on the effort under the umbrella of
a new venue called the WHATWG. A public mailing list was created,
and the draft was moved to the WHATWG site. The copyright was
subsequently amended to be jointly owned by all three vendors, and
to allow reuse of the specification.</p>
<p>The WHATWG was based on several core principles, in particular
that technologies need to be backwards compatible, that
specifications and implementations need to match even if this means
changing the specification rather than the implementations, and that
specifications need to be detailed enough that implementations can
achieve complete interoperability without reverse-engineering each
other.</p>
<p>The latter requirement in particular required that the scope of
the HTML5 specification include what had previously been specified
in three separate documents: HTML4, XHTML1, and DOM2 HTML. It also
meant including significantly more detail than had previously been
considered the norm.</p>
<p>In 2006, the W3C indicated an interest to participate in the
development of HTML5 after all, and in 2007 formed a working group
chartered to work with the WHATWG on the development of the HTML5
specification. Apple, Mozilla, and Opera allowed the W3C to publish
the specification under the W3C copyright, while keeping a version
with the less restrictive license on the WHATWG site.</p>
<p>Since then, both groups have been working together.</p>
<p>A separate document has been published by the W3C HTML working
group to document the differences between this specification and the
language described in the HTML4 specification. <a
href="#refsHTMLDIFF">[HTMLDIFF]</a></p>
<h3>Design notes</h3>
<p><i>This section is non-normative.</i></p>
<p>It must be admitted that many aspects of HTML appear at first
glance to be nonsensical and inconsistent.</p>
<p>HTML, its supporting DOM APIs, as well as many of its supporting
technologies, have been developed over a period of several decades
by a wide array of people with different priorities who, in many
cases, did not know of each other's existence.</p>
<p>Features have thus arisen from many sources, and have not always
been designed in especially consistent ways. Furthermore, because of
the unique characteristics of the Web, implementation bugs have
often become de-facto, and now de-jure, standards, as content is
often unintentionally written in ways that rely on them before they
can be fixed.</p>
<p>Despite all this, efforts have been made to adhere to certain
design goals. These are described in the next few subsections.</p>
<h4>Serializability of script execution</h4>
<p><i>This section is non-normative.</i></p>
<p>To avoid exposing Web authors to the complexities of
multithreading, the HTML and DOM APIs are designed such that no
script can ever detect the simultaneous execution of other
scripts. Even with <span title="Worker">workers</span>, the intent
is that the behavior of implementations can be thought of as
completely serializing the execution of all scripts in all <span
title="browsing context">browsing contexts</span>.</p>
<p class="note">The <code
title="dom-navigator-yieldForStorageUpdates">navigator.yieldForStorageUpdates()</code>
method, in this model, is equivalent to allowing other scripts to
run while the calling script is blocked.</p>
<h4>Compliance with other specifications</h4>
<p><i>This section is non-normative.</i></p>
<p>This specification interacts with and relies on a wide variety of
other specifications. In certain circumstances, unfortunately, the
desire to be compatible with legacy content has led to this
specification violating the requirements of these other
specifications. Whenever this has occurred, the transgressions have
each been noted as a "<dfn>willful violation</dfn>".</p>
<h3>HTML vs XHTML</h3>
<p><i>This section is non-normative.</i></p>
<p>This specification defines an abstract language for describing
documents and applications, and some APIs for interacting with
in-memory representations of resources that use this language.</p>
<p>The in-memory representation is known as "DOM HTML", or "the DOM"
for short. This specification defines version 5 of DOM HTML, known
as "DOM5 HTML".</p>
<p>There are various concrete syntaxes that can be used to transmit
resources that use this abstract language, two of which are defined
in this specification.</p>
<p>The first such concrete syntax is the HTML syntax. This is the
format suggested for most authors. It is compatible with most legacy
Web browsers. If a document is transmitted with the <span>MIME
type</span> <code>text/html</code>, then it will be processed as an
HTML document by Web browsers. This specification defines version 5
of the HTML syntax, known as "HTML5".</p>
<p>The second concrete syntax is the XHTML syntax, which is an
application of XML. When a document is transmitted with an <span>XML
MIME type</span>, such as <code>application/xhtml+xml</code>, then
it is treated as an XML document by Web browsers, to be parsed by an
XML processor. Authors are reminded that the processing for XML and
HTML differs; in particular, even minor syntax errors will prevent a
document labeled as XML from being rendered fully, whereas they
would be ignored in the HTML syntax. This specification defines
version 5 of the XHTML syntax, known as "XHTML5".</p>
<p>The DOM, the HTML syntax, and XML cannot all represent the same
content. For example, namespaces cannot be represented using the
HTML syntax, but they are supported in the DOM and in XML.
Similarly, documents that use the <code>noscript</code> feature can
be represented using the HTML syntax, but cannot be represented with
the DOM or in XML. Comments that contain the string "<code
title="">--></code>" can be represented in the DOM but not in the
HTML syntax or in XML.</p>
<h3>Structure of this specification</h3>
<p><i>This section is non-normative.</i></p>
<p>This specification is divided into the following major
sections:</p>
<dl>
<dt><a href="#infrastructure">Common Infrastructure</a></dt>
<dd>The conformance classes, algorithms, definitions, and the
common underpinnings of the rest of the specification.</dd>
<dt><a href="#dom">Semantics, structure, and APIs of HTML documents</a></dt>
<dd>Documents are built from elements. These elements form a tree
using the DOM. This section defines the features of this DOM, as
well as introducing the features common to all elements, and the
concepts used in defining elements.</dd>
<dt><a href="#semantics">Elements</a></dt>
<dd>Each element has a predefined meaning, which is explained in
this section. Rules for authors on how to use the element<span
class="impl">, along with user agent requirements for how to handle
each element,</span> are also given.</dd>
<dt><a href="#microdata">Microdata</a></dt>
<dd>This specification introduces a mechanism for adding
machine-readable annotations to documents, so that tools can
extract trees of name/value pairs from the document. This section
describes this mechanism<span class="impl"> and some algorithms
that can be used to convert HTML documents into other
formats</span>.
<!--END html--><!--END html5-->
This section also defines some Microdata vocabularies for contact
information, calendar events, and licensing works.
<!--START html--><!--START html5-->
</dd>
<dt><a href="#browsers">Web Browsers</a></dt>
<dd>HTML documents do not exist in a vacuum — this section
defines many of the features that affect environments that deal
with multiple pages, links between pages, and running scripts.</dd>
<!--END html--><!--END html5-->
<dt><a href="#webstorage">Web Storage</a></dt>
<dd>This specification defines a client-side storage mechanism
based on name-value pairs.</dd>
<!--START html--><!--START html5-->
<dt><a href="#editing">User Interaction</a></dt>
<dd>HTML documents can provide a number of mechanisms for users to
interact with and modify content, which are described in this
section.</dd>
<!--END html--><!--END html5-->
<dt><a href="#workers">Web Workers</a></dt>
<dd>This specification defines an API for background threads in
JavaScript.</dd>
<!--START html--><!--START html5-->
<dt><a href="#comms">The Communication APIs</a></dt>
<dd>This section describes some mechanisms that applications
written in HTML can use to communicate with other applications from
different domains running on the same client.
<!--END html--><!--END html5-->
It also introduces a server-push event stream mechanism, and a
two-way full-duplex socket protocol for scripts.
<!--START html--><!--START html5-->
</dd>
<dt><a href="#syntax">The HTML Syntax</a></dt>
<dt><a href="#xhtml">The XHTML Syntax</a></dt>
<dd>All of these features would be for naught if they couldn't be
represented in a serialized form and sent to other people, and so
these sections define the syntaxes of HTML, along with rules for
how to parse content using those syntaxes.</dd>
</dl>
<p>There are also some appendices, defining <a
href="#rendering">rendering rules</a> for Web browsers and listing
<a href="#obsolete">obsolete features</a> and <a href="#iana">IANA
considerations</a>.</p>
<h4>How to read this specification</h4>
<p>This specification should be read like all other specifications.
First, it should be read cover-to-cover, multiple times. Then, it
should be read backwards at least once. Then it should be read by
picking random sections from the contents list and following all the
cross-references.</p>
<h4>Typographic conventions</h4>
<p>This is a definition, requirement, or explanation.</p>
<p class="note">This is a note.</p>
<p class="example">This is an example.</p>
<p class="XXX">This is an open issue.</p>
<p class="warning">This is a warning.</p>
<pre class="idl extract">interface <dfn title="">Example</dfn> {
// this is an IDL definition
};</pre>
<dl class="domintro">
<dt><var title="">variable</var> = <var title="">object</var> . <code title="">method</code>( [ <var title="">optionalArgument</var> ] )</dt>
<dd>
<p>This is a note to authors describing the usage of an interface.</p>
</dd>
</dl>
<pre class="css">/* this is a CSS fragment */</pre>
<p>The defining instance of a term is marked up like <dfn
title="x-this">this</dfn>. Uses of that term are marked up like
<span title="x-this">this</span> or like <i
title="x-this">this</i>.</p>
<p>The defining instance of an element, attribute, or API is marked
up like <dfn title="x-that"><code>this</code></dfn>. References to
that element, attribute, or API are marked up like <code
title="x-that">this</code>.</p>
<p>Other code fragments are marked up <code title="">like
this</code>.</p>
<p>Variables are marked up like <var title="">this</var>.</p>
<p class="impl">This is an implementation requirement.</p>
<h3>A quick introduction to HTML</h3>
<p><i>This section is non-normative.</i></p>
<p>A basic HTML document looks like this:</p>
<pre id="intro-early-example"><!DOCTYPE html>
<html>
<head>
<title>Sample page</title>
</head>
<body>
<h1>Sample page</h1>
<p>This is a <a href="demo.html">simple</a> sample.</p>
<!-- this is a comment -->
</body>
</html></pre>
<p>HTML documents consist of a tree of elements and text. Each
element is denoted in the source by a <span
title="syntax-start-tag">start tag</span>, such as "<code
title=""><body></code>", and an <span title="syntax-end-tag">end
tag</span>, such as "<code title=""></body></code>". (Certain
start tags and end tags can in certain cases be <span
title="syntax-tag-omission">omitted</span> and are implied by other
tags.)</p>
<p>Tags have to be nested such that elements are all completely
within each other, without overlapping:</p>
<pre class="bad"><p>This is <em>very <strong>wrong</em>!</strong></p></pre>
<pre><p>This <em>is <strong>correct</strong>.</em></p></pre>
<p>This specification defines a set of elements that can be used in
HTML, along with rules about the ways in which the elements can be
nested.</p>
<p>Elements can have attributes, which control how the elements
work. In the example below, there is a <span>hyperlink</span>,
formed using the <code>a</code> element and its <code
title="attr-hyperlink-href">href</code> attribute:</p>
<pre><a href="demo.html">simple</a></pre>
<p><span title="syntax-attributes">Attributes</span> are placed
inside the start tag, and consist of a <span
title="syntax-attribute-name">name</span> and a <span
title="syntax-attribute-value">value</span>, separated by an "<code
title="">=</code>" character. The attribute value can be left <a
href="#unquoted">unquoted</a> if it doesn't contain spaces or any of
<code title="">"</code> <code title="">'</code> <code
title="">`</code> <code title="">=</code> <code title=""><</code>
or <code title="">></code>. Otherwise, it has to be quoted using
either single or double quotes. The value, along with the "<code
title="">=</code>" character, can be omitted altogether if the value
is the empty string.</p>
<pre><!-- empty attributes -->
<input name=address disabled>
<input name=address disabled="">
<!-- attributes with a value -->
<input name=address maxlength=200>
<input name=address maxlength='200'>
<input name=address maxlength="200"></pre>
<p>HTML user agents (e.g. Web browsers) then <i>parse</i> this
markup, turning it into a DOM (Document Object Model) tree. A DOM
tree is an in-memory representation of a document.</p>
<p>DOM trees contain several kinds of nodes, in particular a DOCTYPE
node, elements, text nodes, and comment nodes.</p>
<p>The <a href="#intro-early-example">markup snippet at the top of
this section</a> would be turned into the following DOM tree:</p>
<ul class="domTree"><li class="t10">DOCTYPE: <code>html</code></li><li class="t1"><code>html</code><ul><li class="t1"><code>head</code><ul><li class="t3"><code>#text</code>: <span title="">⏎␣␣</span></li><li class="t1"><code>title</code><ul><li class="t3"><code>#text</code>: <span title="">Sample page</span></li></ul></li><li class="t3"><code>#text</code>: <span title="">⏎␣</span></li></ul></li><li class="t3"><code>#text</code>: <span title="">⏎␣</span></li><li class="t1"><code>body</code><ul><li class="t3"><code>#text</code>: <span title="">⏎␣␣</span></li><li class="t1"><code>h1</code><ul><li class="t3"><code>#text</code>: <span title="">Sample page</span></li></ul></li><li class="t3"><code>#text</code>: <span title="">⏎␣␣</span></li><li class="t1"><code>p</code><ul><li class="t3"><code>#text</code>: <span title="">This is a </span></li><li class="t1"><code>a</code> <span title="" class="t2"><code class="attribute name">href</code>="<code class="attribute value">demo.html</code>"</span><ul><li class="t3"><code>#text</code>: <span title="">simple</span></li></ul></li><li class="t3"><code>#text</code>: <span title=""> sample.</span></li></ul></li><li class="t3"><code>#text</code>: <span title="">⏎␣␣</span></li><li class="t8"><code>#comment</code>: <span title=""> this is a comment </span></li><li class="t3"><code>#text</code>: <span title="">⏎␣⏎</span></li></ul></li></ul></li></ul>
<p>The <span>root element</span> of this tree is the
<code>html</code> element, which is the element always found at the
root of HTML documents. It contains two elements, <code>head</code>
and <code>body</code>, as well as a text node between them.</p>
<p>There are many more text nodes in the DOM tree than one would
initially expect, because the source contains a number of spaces
(represented here by "␣") and line breaks ("⏎") that
all end up as text nodes in the DOM.</p>
<p>The <code>head</code> element contains a <code>title</code>
element, which itself contains a text node with the text "Sample
page". Similarly, the <code>body</code> element contains an
<code>h1</code> element, a <code>p</code> element, and a
comment.</p>
<hr>
<p>This DOM tree can be manipulated from scripts in the
page. Scripts (typically in JavaScript) are small programs that can
be embedded using the <code>script</code> element or using
<span>event handler content attributes</span>. For example, here is
a form with a script that sets the value of the form's
<code>output</code> element to say "Hello World":</p>
<pre><<span>form</span> <span title="attr-form-name">name</span>="main">
Result: <<span>output</span> <span title="attr-fe-name">name</span>="result"></output>
<<span>script</span>>
<span title="HTMLDocument">document</span>.<span title="dom-document-forms">forms</span>.main.<span title="dom-form-elements">elements</span>.result.<span title="dom-output-value">value</span> = 'Hello World';
</script>
</form></pre>
<p>Each element in the DOM tree is represented by an object, and
these objects have APIs so that they can be manipulated. For
instance, a link (e.g. the <code>a</code> element in the tree above)
can have its "<code title="attr-hyperlink-href">href</code>"
attribute changed in several ways:</p>
<pre>var a = <span title="HTMLDocument">document</span>.<span title="dom-document-links">links</span>[0]; // obtain the first link in the document
a.<span title="dom-a-href">href</span> = 'sample.html'; // change the destination URL of the link
a.<span title="dom-uda-protocol">protocol</span> = 'https'; // change just the scheme part of the URL
a.setAttribute('href', 'http://example.com/'); // change the content attribute directly</pre>
<p>Since DOM trees are used as the way to represent HTML documents
when they are processed and presented by implementations (especially
interactive implementations like Web browsers), this specification
is mostly phrased in terms of DOM trees, instead of the markup
described above.</p>
<hr>
<p>HTML documents represent a media-independent description of
interactive content. HTML documents might be rendered to a screen,
or through a speech synthesizer, or on a braille display. To
influence exactly how such rendering takes place, authors can use a
styling language such as CSS.</p>
<p>In the following example, the page has been made yellow-on-blue
using CSS.</p>
<pre><!DOCTYPE html>
<html>
<head>
<title>Sample styled page</title>
<style>
body { background: navy; color: yellow; }
</style>
</head>
<body>
<h1>Sample styled page</h1>
<p>This page is just a demo.</p>
</body>
</html></pre>
<p>For more details on how to use HTML, authors are encouraged to
consult tutorials and guides. Some of the examples included in this
specification might also be of use, but the novice author is
cautioned that this specification, by necessity, defines the
language with a level of detail that might be difficult to
understand at first.</p>
<h3>Recommended reading</h3>
<p><i>This section is non-normative.</i></p>
<p>The following documents might be of interest to readers of this
specification.</p>
<dl>
<dt><cite>Character Model for the World Wide Web 1.0: Fundamentals</cite> <a href="#refsCHARMOD">[CHARMOD]</a></dt>
<dd><blockquote><p>This Architectural Specification provides
authors of specifications, software developers, and content
developers with a common reference for interoperable text
manipulation on the World Wide Web, building on the Universal
Character Set, defined jointly by the Unicode Standard and ISO/IEC
10646. Topics addressed include use of the terms 'character',
'encoding' and 'string', a reference processing model, choice and
identification of character encodings, character escaping, and
string indexing.</p></blockquote></dd>
<dt><cite>Unicode Security Considerations</cite> <a href="#refsUTR36">[UTR36]</a></dt>
<dd><blockquote><p>Because Unicode contains such a large number of
characters and incorporates the varied writing systems of the
world, incorrect usage can expose programs or systems to possible
security attacks. This is especially important as more and more
products are internationalized. This document describes some of the
security considerations that programmers, system analysts,
standards developers, and users should take into account, and
provides specific recommendations to reduce the risk of
problems.</p></blockquote></dd>
<dt><cite>Web Content Accessibility Guidelines (WCAG) 2.0</cite> <a href="#refsWCAG">[WCAG]</a></dt>
<dd><blockquote><p>Web Content Accessibility Guidelines (WCAG) 2.0
covers a wide range of recommendations for making Web content more
accessible. Following these guidelines will make content accessible
to a wider range of people with disabilities, including blindness
and low vision, deafness and hearing loss, learning disabilities,
cognitive limitations, limited movement, speech disabilities,
photosensitivity and combinations of these. Following these
guidelines will also often make your Web content more usable to
users in general.</p></blockquote></dd>
<dt class="impl"><cite>Authoring Tool Accessibility Guidelines (ATAG) 2.0</cite> <a href="#refsATAG">[ATAG]</a></dt>
<dd class="impl"><blockquote><p>This specification provides
guidelines for designing Web content authoring tools that are more
accessible for people with disabilities. An authoring tool that
conforms to these guidelines will promote accessibility by
providing an accessible user interface to authors with disabilities
as well as by enabling, supporting, and promoting the production of
accessible Web content by all authors.</p></blockquote></dd>
<dt class="impl"><cite>User Agent Accessibility Guidelines (UAAG) 2.0</cite> <a href="#refsUAAG">[UAAG]</a></dt>
<dd class="impl"><blockquote><p>This document provides guidelines
for designing user agents that lower barriers to Web accessibility
for people with disabilities. User agents include browsers and
other types of software that retrieve and render Web content. A
user agent that conforms to these guidelines will promote
accessibility through its own user interface and through other
internal facilities, including its ability to communicate with
other technologies (especially assistive
technologies). Furthermore, all users, not just users with
disabilities, should find conforming user agents to be more
usable.</p></blockquote></dd>
</dl>
<h2 id="infrastructure">Common infrastructure</h2>
<h3>Terminology</h3>
<p>This specification refers to both HTML and XML attributes and IDL
attributes, often in the same context. When it is not clear which is
being referred to, they are referred to as <dfn title="">content
attributes</dfn> for HTML and XML attributes, and <dfn title="">IDL
attributes</dfn> for those defined on IDL interfaces. Similarly, the
term "properties" is used for both JavaScript object properties and
CSS properties. When these are ambiguous they are qualified as <dfn
title="">object properties</dfn> and <dfn title="">CSS
properties</dfn> respectively.</p>
<p>Generally, when the specification states that a feature applies
to <span>the HTML syntax</span> or <span>the XHTML syntax</span>, it
also includes the other. When a feature specifically only applies to
one of the two languages, it is called out by explicitly stating
that it does not apply to the other format, as in "for HTML,
... (this does not apply to XHTML)".</p>
<p>This specification uses the term <dfn title="">document</dfn> to
refer to any use of HTML, ranging from short static documents to
long essays or reports with rich multimedia, as well as to
fully-fledged interactive applications.</p>
<p>For simplicity, terms such as <dfn title="">shown</dfn>, <dfn
title="">displayed</dfn>, and <dfn title="">visible</dfn> might
sometimes be used when referring to the way a document is rendered
to the user. These terms are not meant to imply a visual medium;
they must be considered to apply to other media in equivalent
ways.</p>
<p>When an algorithm B says to return to another algorithm A, it
implies that A called B. Upon returning to A, the implementation
must continue from where it left off in calling B.</p>
<h4>Resources</h4>
<p>The specification uses the term <dfn title="">supported</dfn>
when referring to whether a user agent has an implementation capable
of decoding the semantics of an external resource. A format or type
is said to be <i>supported</i> if the implementation can process an
external resource of that format or type without critical aspects of
the resource being ignored. Whether a specific resource is
<i>supported</i> can depend on what features of the resource's
format are in use.</p>
<p class="example">For example, a PNG image would be considered to
be in a supported format if its pixel data could be decoded and
rendered, even if, unbeknownst to the implementation, the image also
contained animation data.</p>
<p class="example">A MPEG4 video file would not be considered to be
in a supported format if the compression format used was not
supported, even if the implementation could determine the dimensions
of the movie from the file's metadata.</p>
<p>The term <dfn>MIME type</dfn> is used to refer to what is
sometimes called an <i>Internet media type</i> in protocol
literature. The term <i>media type</i> in this specification is used
to refer to the type of media intended for presentation, as used by
the CSS specifications. <a href="#refsRFC2046">[RFC2046]</a> <a
href="#refsMQ">[MQ]</a></p>
<p>A string is a <dfn>valid MIME type</dfn> if it matches the <code
title="">media-type</code> rule defined in section 3.7 "Media
Types" of RFC 2616. <a href="#refsHTTP">[HTTP]</a></p>
<h4>XML</h4>
<p id="html-namespace">To ease migration from HTML to XHTML, UAs
conforming to this specification will place elements in HTML in the
<code>http://www.w3.org/1999/xhtml</code> namespace, at least for
the purposes of the DOM and CSS. The term "<dfn>HTML
elements</dfn>", when used in this specification, refers to any
element in that namespace, and thus refers to both HTML and XHTML
elements.</p>
<p>Except where otherwise stated, all elements defined or mentioned
in this specification are in the
<code>http://www.w3.org/1999/xhtml</code> namespace, and all
attributes defined or mentioned in this specification have no
namespace.</p>
<p>Attribute names are said to be <dfn>XML-compatible</dfn> if they
match the <a href="http://www.w3.org/TR/REC-xml/#NT-Name"><code
title="">Name</code></a> production defined in XML, they contain no
U+003A COLON characters (:), and their first three characters are
not an <span>ASCII case-insensitive</span> match for the string
"<code title="">xml</code>". <a href="#refsXML">[XML]</a></p>
<p>The term <dfn>XML MIME type</dfn> is used to refer to the <span
title="MIME type">MIME types</span> <code title="">text/xml</code>,
<code title="">application/xml</code>, and any <span>MIME
type</span> whose subtype ends with the four characters "<code
title="">+xml</code>". <a href="#refsRFC3023">[RFC3023]</a></p>
<h4>DOM trees</h4>
<p>The term <dfn>root element</dfn>, when not explicitly qualified
as referring to the document's root element, means the furthest
ancestor element node of whatever node is being discussed, or the
node itself if it has no ancestors. When the node is a part of the
document, then that is indeed the document's root element; however,
if the node is not currently part of the document tree, the root
element will be an orphaned node.</p>
<p>A node's <dfn>home subtree</dfn> is the subtree rooted at that
node's <span>root element</span>.</p>
<p>The <code>Document</code> of a <code>Node</code> (such as an
element) is the <code>Document</code> that the <code>Node</code>'s
<code title="">ownerDocument</code> IDL attribute returns.</p>
<p>When an element's <span>root element</span> is the <span>root
element</span> of a <code>Document</code>, it is said to be <dfn>in
a <code>Document</code></dfn>. An element is said to have been <dfn
title="insert an element into a document">inserted into a
document</dfn> when its <span>root element</span> changes and is now
the document's <span>root element</span>. Analogously, an element is
said to have been <dfn title="remove an element from a
document">removed from a document</dfn> when its <span>root
element</span> changes from being the document's <span>root
element</span> to being another element.</p>
<p>If a <code>Node</code> is <span>in a <code>Document</code></span>
then that <code>Document</code> is always the <code>Node</code>'s
<code>Document</code>, and the <code>Node</code>'s <code
title="">ownerDocument</code> IDL attribute thus always returns that
<code>Document</code>.</p>
<p>The term <dfn>tree order</dfn> means a pre-order, depth-first
traversal of DOM nodes involved (through the <code
title="">parentNode</code>/<code title="">childNodes</code>
relationship).</p>
<p>When it is stated that some element or attribute is <dfn
title="ignore">ignored</dfn>, or treated as some other value, or
handled as if it was something else, this refers only to the
processing of the node after it is in the DOM. <span class="impl">A
user agent must not mutate the DOM in such situations.</span></p>
<p>The term <dfn>text node</dfn> refers to any <code>Text</code>
node, including <code>CDATASection</code> nodes; specifically, any
<code>Node</code> with node type <code title="">TEXT_NODE</code> (3)
or <code title="">CDATA_SECTION_NODE</code> (4). <a
href="#refsDOMCORE">[DOMCORE]</a></p>
<p>A content attribute is said to <dfn title="">change</dfn> value
only if its new value is different than its previous value; setting
an attribute to a value it already has does not change it.</p>
<h4>Scripting</h4>
<p>The construction "a <code>Foo</code> object", where
<code>Foo</code> is actually an interface, is sometimes used instead
of the more accurate "an object implementing the interface
<code>Foo</code>".</p>
<p>An IDL attribute is said to be <dfn title="">getting</dfn> when
its value is being retrieved (e.g. by author script), and is said to
be <dfn title="">setting</dfn> when a new value is assigned to
it.</p>
<p>If a DOM object is said to be <dfn>live</dfn>, then that means
that any attributes returning that object <span
class="impl">must</span> always return the same object (not a new
object each time), and the attributes and methods on that object
<span class="impl">must</span> operate on the actual underlying
data, not a snapshot of the data.</p>
<p>The terms <dfn title="">fire</dfn> and <dfn title="">dispatch</dfn> are used
interchangeably in the context of events, as in the DOM Events
specifications. <a href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<h4>Plugins</h4>
<p>The term <dfn>plugin</dfn> is used to mean any content handler
for Web content types that are either not supported by the user
agent natively or that do not expose a DOM, which supports rendering
the content as part of the user agent's interface.</p>
<p>Typically such content handlers are provided by third
parties.</p>
<p class="example">One example of a plugin would be a PDF viewer
that is instantiated in a <span>browsing context</span> when the
user navigates to a PDF file. This would count as a plugin
regardless of whether the party that implemented the PDF viewer
component was the same as that which implemented the user agent
itself. However, a PDF viewer application that launches separate
from the user agent (as opposed to using the same interface) is not
a plugin by this definition.</p>
<p class="note">This specification does not define a mechanism for
interacting with plugins, as it is expected to be user-agent- and
platform-specific. Some UAs might opt to support a plugin mechanism
such as the Netscape Plugin API; others might use remote content
converters or have built-in support for certain types. <a
href="#refsNPAPI">[NPAPI]</a></p>
<p class="warning">Browsers should take extreme care when
interacting with external content intended for <span
title="plugin">plugins</span>. When third-party software is run with
the same privileges as the user agent itself, vulnerabilities in the
third-party software become as dangerous as those in the user
agent.</p>
<h4>Character encodings</h4>
<p>The <dfn>preferred MIME name</dfn> of a character encoding is the
name or alias labeled as "preferred MIME name" in the IANA
<cite>Character Sets</cite> registry, if there is one, or the
encoding's name, if none of the aliases are so labeled. <a
href="#refsIANACHARSET">[IANACHARSET]</a></p>
<p>An <dfn>ASCII-compatible character encoding</dfn> is a
single-byte or variable-length encoding in which the bytes 0x09,
0x0A, 0x0C, 0x0D, 0x20 - 0x22, 0x26, 0x27, 0x2C - 0x3F, 0x41 - 0x5A,
and 0x61 - 0x7A<!-- is that list ok? do any character sets we want
to support do things outside that range? -->, ignoring bytes that
are the second and later bytes of multibyte sequences, all
correspond to single-byte sequences that map to the same Unicode
characters as those bytes in ANSI_X3.4-1968 (US-ASCII). <a
href="#refsRFC1345">[RFC1345]</a></p>
<p class="note">This includes such encodings as Shift_JIS,
HZ-GB-2312, and variants of ISO-2022, even though it is possible in
these encodings for bytes like 0x70 to be part of longer sequences
that are unrelated to their interpretation as ASCII. It excludes
such encodings as UTF-7, UTF-16, GSM03.38, and EBCDIC variants.</p>
<!--
We'll have to change that if anyone comes up with a way to have a
document that is valid as two different encodings at once, with
different <meta charset> elements applying in each case.
-->
<p>The term <dfn title="">Unicode character</dfn> is used to mean a
<i title="">Unicode scalar value</i> (i.e. any Unicode code point
that is not a surrogate code point). <a
href="#refsUNICODE">[UNICODE]</a></p>
<h3>Conformance requirements</h3>
<p>All diagrams, examples, and notes in this specification are
non-normative, as are all sections explicitly marked non-normative.
Everything else in this specification is normative.</p>
<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in the normative parts of this document are to be
interpreted as described in RFC2119. For readability, these words do
not appear in all uppercase letters in this specification. <a
href="#refsRFC2119">[RFC2119]</a></p>
<p class="impl">Requirements phrased in the imperative as part of
algorithms (such as "strip any leading space characters" or "return
false and abort these steps") are to be interpreted with the meaning
of the key word ("must", "should", "may", etc) used in introducing
the algorithm.</p>
<p>This specification describes the conformance criteria for <span
class="impl">user agents (relevant to implementors) and</span>
documents<span class="impl"> (relevant to authors and authoring tool
implementors)</span>.</p>
<p class="note impl">There is no implied relationship between
document conformance requirements and implementation conformance
requirements. User agents are not free to handle non-conformant
documents as they please; the processing model described in this
specification applies to implementations regardless of the
conformity of the input documents.</p>
<div class="impl">
<!-- put this list into its own section -->
<p>User agents fall into several (overlapping) categories with
different conformance requirements.</p>
<dl>
<dt id="interactive">Web browsers and other interactive user agents</dt>
<dd>
<p>Web browsers that support <span>the XHTML syntax</span> must
process elements and attributes from the <span>HTML
namespace</span> found in XML documents as described in this
specification, so that users can interact with them, unless the
semantics of those elements have been overridden by other
specifications.</p>
<p class="example">A conforming XHTML processor would, upon
finding an XHTML <code>script</code> element in an XML document,
execute the script contained in that element. However, if the
element is found within a transformation expressed in XSLT
(assuming the user agent also supports XSLT), then the processor
would instead treat the <code>script</code> element as an opaque
element that forms part of the transform.</p>
<p>Web browsers that support <span>the HTML syntax</span> must
process documents labeled as <code>text/html</code> as described
in this specification, so that users can interact with them.</p>
<p>User agents that support scripting must also be conforming
implementations of the IDL fragments in this specification, as
described in the Web IDL specification. <a
href="#refsWEBIDL">[WEBIDL]</a></p>
<p class="note">Unless explicitly stated, specifications that
override the semantics of HTML elements do not override the
requirements on DOM objects representing those elements. For
example, the <code>script</code> element in the example above
would still implement the <code>HTMLScriptElement</code>
interface.</p>
</dd>
<dt id="non-interactive">Non-interactive presentation user agents</dt>
<dd>
<p>User agents that process HTML and XHTML documents purely to
render non-interactive versions of them must comply to the same
conformance criteria as Web browsers, except that they are exempt
from requirements regarding user interaction.</p>
<p class="note">Typical examples of non-interactive presentation
user agents are printers (static UAs) and overhead displays
(dynamic UAs). It is expected that most static non-interactive
presentation user agents will also opt to <a
href="#non-scripted">lack scripting support</a>.</p>
<p class="example">A non-interactive but dynamic presentation UA
would still execute scripts, allowing forms to be dynamically
submitted, and so forth. However, since the concept of "focus" is
irrelevant when the user cannot interact with the document, the UA
would not need to support any of the focus-related DOM APIs.</p>
</dd>
<dt><dfn id="non-scripted">User agents with no scripting support</dfn></dt>
<dd>
<p>Implementations that do not support scripting (or which have
their scripting features disabled entirely) are exempt from
supporting the events and DOM interfaces mentioned in this
specification. For the parts of this specification that are
defined in terms of an events model or in terms of the DOM, such
user agents must still act as if events and the DOM were
supported.</p>
<p class="note">Scripting can form an integral part of an
application. Web browsers that do not support scripting, or that
have scripting disabled, might be unable to fully convey the
author's intent.</p>
</dd>
<dt>Conformance checkers</dt>
<dd id="conformance-checkers">
<p>Conformance checkers must verify that a document conforms to
the applicable conformance criteria described in this
specification. Automated conformance checkers are exempt from
detecting errors that require interpretation of the author's
intent (for example, while a document is non-conforming if the
content of a <code>blockquote</code> element is not a quote,
conformance checkers running without the input of human judgement
do not have to check that <code>blockquote</code> elements only
contain quoted material).</p>
<p>Conformance checkers must check that the input document
conforms when parsed without a <span>browsing context</span>
(meaning that no scripts are run, and that the parser's
<span>scripting flag</span> is disabled), and should also check
that the input document conforms when parsed with a <span>browsing
context</span> in which scripts execute, and that the scripts
never cause non-conforming states to occur other than transiently
during script execution itself. (This is only a "SHOULD" and not a
"MUST" requirement because it has been proven to be impossible. <a
href="#refsCOMPUTABLE">[COMPUTABLE]</a>)</p>
<p>The term "HTML5 validator" can be used to refer to a
conformance checker that itself conforms to the applicable
requirements of this specification.</p>
<div class="note">
<p>XML DTDs cannot express all the conformance requirements of
this specification. Therefore, a validating XML processor and a
DTD cannot constitute a conformance checker. Also, since neither
of the two authoring formats defined in this specification are
applications of SGML, a validating SGML system cannot constitute
a conformance checker either.</p>
<p>To put it another way, there are three types of conformance
criteria:</p>
<ol>
<li>Criteria that can be expressed in a DTD.</li>
<li>Criteria that cannot be expressed by a DTD, but can still be
checked by a machine.</li>
<li>Criteria that can only be checked by a human.</li>
</ol>
<p>A conformance checker must check for the first two. A simple
DTD-based validator only checks for the first class of errors and
is therefore not a conforming conformance checker according to
this specification.</p>
</div>
</dd>
<dt>Data mining tools</dt>
<dd id="data-mining">
<p>Applications and tools that process HTML and XHTML documents
for reasons other than to either render the documents or check
them for conformance should act in accordance with the semantics
of the documents that they process.</p>
<p class="example">A tool that generates <span
title="outline">document outlines</span> but increases the nesting
level for each paragraph and does not increase the nesting level
for each section would not be conforming.</p>
</dd>
<dt id="editors">Authoring tools and markup generators</dt>
<dd>
<p>Authoring tools and markup generators must generate conforming
documents. Conformance criteria that apply to authors also apply
to authoring tools, where appropriate.</p>
<p>Authoring tools are exempt from the strict requirements of
using elements only for their specified purpose, but only to the
extent that authoring tools are not yet able to determine author
intent.</p>
<p class="example">For example, it is not conforming to use an
<code>address</code> element for arbitrary contact information;
that element can only be used for marking up contact information
for the author of the document or section. However, since an
authoring tool is likely unable to determine the difference, an
authoring tool is exempt from that requirement.</p>
<p class="note">In terms of conformance checking, an editor has to
output documents that conform to the same extent that a
conformance checker will verify.</p>
<p>When an authoring tool is used to edit a non-conforming
document, it may preserve the conformance errors in sections of
the document that were not edited during the editing session
(i.e. an editing tool is allowed to round-trip erroneous
content). However, an authoring tool must not claim that the
output is conformant if errors have been so preserved.</p>
<p>Authoring tools are expected to come in two broad varieties:
tools that work from structure or semantic data, and tools that
work on a What-You-See-Is-What-You-Get media-specific editing
basis (WYSIWYG).</p>
<p>The former is the preferred mechanism for tools that author
HTML, since the structure in the source information can be used to
make informed choices regarding which HTML elements and attributes
are most appropriate.</p>
<p>However, WYSIWYG tools are legitimate. WYSIWYG tools should use
elements they know are appropriate, and should not use elements
that they do not know to be appropriate. This might in certain
extreme cases mean limiting the use of flow elements to just a few
elements, like <code>div</code>, <code>b</code>, <code>i</code>,
and <code>span</code> and making liberal use of the <code
title="attr-style">style</code> attribute.</p>
<p>All authoring tools, whether WYSIWYG or not, should make a best
effort attempt at enabling users to create well-structured,
semantically rich, media-independent content.</p>
</dd>
</dl>
<p>Some conformance requirements are phrased as requirements on
elements, attributes, methods or objects. Such requirements fall
into two categories: those describing content model restrictions,
and those describing implementation behavior. Those in the former
category are requirements on documents and authoring tools. Those in
the second category are requirements on user agents. Similarly, some
conformance requirements are phrased as requirements on authors;
such requirements are to be interpreted as conformance requirements
on the documents that authors produce. (In other words, this
specification does not distinguish between conformance criteria on
authors and conformance criteria on documents.)</p>
<p>Conformance requirements phrased as algorithms or specific steps
may be implemented in any manner, so long as the end result is
equivalent. (In particular, the algorithms defined in this
specification are intended to be easy to follow, and not intended to
be performant.)</p>
<p id="hardwareLimitations">User agents may impose
implementation-specific limits on otherwise unconstrained inputs,
e.g. to prevent denial of service attacks, to guard against running
out of memory, or to work around platform-specific limitations.</p>
</div>
<p>For compatibility with existing content and prior specifications,
this specification describes two authoring formats: one based on XML
(referred to as <span>the XHTML syntax</span>), and one using a <a
href="#writing">custom format</a> inspired by SGML (referred to as
<span>the HTML syntax</span>). <span class="impl">Implementations
may support only one of these two formats, although supporting both
is encouraged.</span></p>
<p id="authors-using-xhtml">XML documents that use elements or
attributes from the <span>HTML namespace</span> and that are served
over the wire (e.g. by HTTP) must be sent using an <span>XML MIME
type</span> such as <code>application/xml</code> or
<code>application/xhtml+xml</code> and must not be served as
<code>text/html</code>. <a href="#refsRFC3023">[RFC3023]</a></p>
<p id="authors-using-html">Documents that use <span>the HTML
syntax</span>, if they are served over the wire (e.g. by HTTP) must
be labeled with the <code>text/html</code> <span>MIME
type</span>.</p>
<p id="entity-references" class="impl">The language in this
specification assumes that the user agent expands all entity
references, and therefore does not include entity reference nodes in
the DOM. If user agents do include entity reference nodes in the
DOM, then user agents must handle them as if they were fully
expanded when implementing this specification. For example, if a
requirement talks about an element's child text nodes, then any text
nodes that are children of an entity reference that is a child of
that element would be used as well. Entity references to unknown
entities must be treated as if they contained just an empty text
node for the purposes of the algorithms defined in this
specification.</p>
<div class="impl">
<h4>Dependencies</h4>
<p>This specification relies on several other underlying
specifications.</p>
<dl>
<dt>XML</dt>
<dd>
<p>Implementations that support <span>the XHTML syntax</span> must
support some version of XML, as well as its corresponding
namespaces specification, because that syntax uses an XML
serialization with namespaces. <a href="#refsXML">[XML]</a> <a
href="#refsXMLNS">[XMLNS]</a></p>
</dd>
<dt>DOM</dt>
<dd>
<p>The Document Object Model (DOM) is a representation — a
model — of a document and its content. The DOM is not just
an API; the conformance criteria of HTML implementations are
defined, in this specification, in terms of operations on the DOM.
<a href="#refsDOMCORE">[DOMCORE]</a></p>
<p>Implementations must support some version of DOM Core and DOM
Events, because this specification is defined in terms of the DOM,
and some of the features are defined as extensions to the DOM Core
interfaces. <a href="#refsDOMCORE">[DOMCORE]</a> <a
href="#refsDOMCORE">[DOMEVENTS]</a></p>
</dd>
<dt>Web IDL</dt>
<dd>
<p>The IDL fragments in this specification must be interpreted as
required for conforming IDL fragments, as described in the Web IDL
specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
<p id="float-nan">Except where otherwise specified, if an IDL
attribute that is a floating point number type (<code
title="">float</code>) is assigned an Infinity or Not-a-Number
(NaN) value, a <code>NOT_SUPPORTED_ERR</code> exception must be
raised.</p>
<p>Except where otherwise specified, if a method with an argument
that is a floating point number type (<code title="">float</code>)
is passed an Infinity or Not-a-Number (NaN) value, a
<code>NOT_SUPPORTED_ERR</code> exception must be raised.</p>
</dd>
<dt>JavaScript</dt>
<dd>
<p>Some parts of the language described by this specification only
support JavaScript as the underlying scripting language. <a
href="#refsECMA262">[ECMA262]</a></p>
<p class="note">The term "JavaScript" is used to refer to ECMA262,
rather than the official term ECMAScript, since the term
JavaScript is more widely known. Similarly, the <span>MIME
type</span> used to refer to JavaScript in this specification is
<code title="">text/javascript</code>, since that is the most
commonly used type, <span title="willful violation">despite it
being an officially obsoleted type</span> according to RFC
4329. <a href="#refsRFC4329">[RFC4329]</a></p>
</dd>
<dt>Media Queries</dt>
<dd>
<p>Implementations must support some version of the Media Queries
language. <a href="#refsMQ">[MQ]</a></p>
</dd>
<dt>URIs, IRIs, IDNA</dt>
<dd>
<p>Implementations must support the semantics of <span
title="URL">URLs</span> defined in the URI and IRI specifications,
as well as the semantics of IDNA domain names defined in the
<cite>Internationalizing Domain Names in Applications
(IDNA)</cite> specification. <a href="#refsRFC3986">[RFC3986]</a>
<a href="#refsRFC3987">[RFC3987]</a> <a
href="#refsRFC3490">[RFC3490]</a>
</dd>
</dl>
<p>This specification does not <em>require</em> support of any
particular network transport protocols, style sheet language,
scripting language, or any of the DOM specifications beyond those
described above. However, the language described by this
specification is biased towards CSS as the styling language,
JavaScript as the scripting language, and HTTP as the network
protocol, and several features assume that those languages and
protocols are in use.</p>
<p class="note">This specification might have certain additional
requirements on character encodings, image formats, audio formats,
and video formats in the respective sections.</p>
</div>
<div class="impl">
<h4>Extensibility</h4>
<p>Vendor-specific proprietary extensions to this specification are
strongly discouraged. Documents must not use such extensions, as
doing so reduces interoperability and fragments the user base,
allowing only users of specific user agents to access the content in
question.</p>
<p>If vendor-specific markup extensions are needed, they should be
done using XML, with elements or attributes from custom
namespaces. If such DOM extensions are needed, the members should be
prefixed by vendor-specific strings to prevent clashes with future
versions of this specification. Extensions must be defined so that
the use of extensions neither contradicts nor causes the
non-conformance of functionality defined in the specification.</p>
<!-- thanks to QA Framework -->
<div class="example">
<p>For example, while strongly discouraged from doing so, an
implementation "Foo Browser" could add a new IDL attribute "<code
title="">fooTypeTime</code>" to a control's DOM interface that
returned the time it took the user to select the current value of a
control (say). On the other hand, defining a new control that
appears in a form's <code title="dom-form-elements">elements</code>
array would be in violation of the above requirement, as it would
violate the definition of <code
title="dom-form-elements">elements</code> given in this
specification.</p>
</div>
<hr>
<p>When vendor-neutral extensions to this specification are needed,
either this specification can be updated accordingly, or an
extension specification can be written that overrides the
requirements in this specification. When someone applying this
specification to their activities decides that they will recognise
the requirements of such an extension specification, it becomes an
<dfn title="other applicable specifications">applicable
specification</dfn> for the purposes of conformance requirements in
this specification.</p>
<!-- http://www.w3.org/mid/17E341CD-E790-422C-9F9A-69347EE01CEB@iki.fi -->
<hr>
<p>User agents must treat elements and attributes that they do not
understand as semantically neutral; leaving them in the DOM (for DOM
processors), and styling them according to CSS (for CSS processors),
but not inferring any meaning from them.</p>
</div>
<h3>Case-sensitivity and string comparison</h3>
<p>Comparing two strings in a <dfn>case-sensitive</dfn> manner means
comparing them exactly, code point for code point.</p>
<p>Comparing two strings in an <dfn>ASCII case-insensitive</dfn>
manner means comparing them exactly, code point for code point, except
that the characters in the range U+0041 to U+005A (i.e. LATIN
CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and the corresponding
characters in the range U+0061 to U+007A (i.e. LATIN SMALL LETTER A
to LATIN SMALL LETTER Z) are considered to also match.</p>
<p>Comparing two strings in a <dfn>compatibility caseless</dfn>
manner means using the Unicode <i>compatibility caseless match</i>
operation to compare the two strings. <a
href="#refsUNICODE">[UNICODE]</a></p>
<div class="impl">
<p><dfn title="converted to ASCII uppercase">Converting a string to
ASCII uppercase</dfn> means replacing all characters in the range
U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z)
with the corresponding characters in the range U+0041 to U+005A
(i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).</p>
<p><dfn title="converted to ASCII lowercase">Converting a string to
ASCII lowercase</dfn> means replacing all characters in the range
U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL
LETTER Z) with the corresponding characters in the range U+0061
to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z).</p>
</div>
<p>A string <var title="">pattern</var> is a <dfn>prefix match</dfn>
for a string <var title="">s</var> when <var title="">pattern</var>
is not longer than <var title="">s</var> and truncating <var
title="">s</var> to <var title="">pattern</var>'s length leaves the
two strings as matches of each other.</p>
<h3>Common microsyntaxes</h3>
<p>There are various places in HTML that accept particular data
types, such as dates or numbers. This section describes what the
conformance criteria for content in those formats is, and how to
parse them.</p>
<div class="impl">
<p class="note">Implementors are strongly urged to carefully examine
any third-party libraries they might consider using to implement the
parsing of syntaxes described below. For example, date libraries are
likely to implement error handling behavior that differs from what
is required in this specification, since error-handling behavior is
often not defined in specifications that describe date syntaxes
similar to those used in this specification, and thus
implementations tend to vary greatly in how they handle errors.</p>
</div>
<div class="impl">
<h4>Common parser idioms</h4>
<p>The <dfn title="space character">space characters</dfn>, for the
purposes of this specification, are U+0020 SPACE, U+0009 CHARACTER
TABULATION (tab), U+000A LINE FEED (LF), U+000C FORM FEED (FF), and
U+000D CARRIAGE RETURN (CR).</p>
<p>The <dfn title="White_Space">White_Space characters</dfn> are
those that have the Unicode property "White_Space". <a
href="#refsUNICODE">[UNICODE]</a></p>
<p>The <dfn>alphanumeric ASCII characters</dfn> are those in the
ranges U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN
CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, U+0061 LATIN
SMALL LETTER A to U+007A LATIN SMALL LETTER Z.</p>
<p>Some of the micro-parsers described below follow the pattern of
having an <var title="">input</var> variable that holds the string
being parsed, and having a <var title="">position</var> variable
pointing at the next character to parse in <var
title="">input</var>.</p>
<p>For parsers based on this pattern, a step that requires the user
agent to <dfn>collect a sequence of characters</dfn> means that the
following algorithm must be run, with <var title="">characters</var>
being the set of characters that can be collected:</p>
<ol>
<li><p>Let <var title="">input</var> and <var
title="">position</var> be the same variables as those of the same
name in the algorithm that invoked these steps.</p></li>
<li><p>Let <var title="">result</var> be the empty string.</p></li>
<li><p>While <var title="">position</var> doesn't point past the
end of <var title="">input</var> and the character at <var
title="">position</var> is one of the <var
title="">characters</var>, append that character to the end of <var
title="">result</var> and advance <var title="">position</var> to
the next character in <var title="">input</var>.</p></li>
<li><p>Return <var title="">result</var>.</p></li>
</ol>
<p>The step <dfn>skip whitespace</dfn> means that the user agent
must <span>collect a sequence of characters</span> that are <span
title="space character">space characters</span>. The step <dfn>skip
White_Space characters</dfn> means that the user agent must
<span>collect a sequence of characters</span> that are
<span>White_Space</span> characters. In both cases, the collected
characters are not used. <a href="#refsUNICODE">[UNICODE]</a></p>
<p>When a user agent is to <dfn>strip line breaks</dfn> from a
string, the user agent must remove any U+000A LINE FEED (LF) and
U+000D CARRIAGE RETURN (CR) characters from that string.</p>
<p>The <dfn>code-point length</dfn> of a string is the number of
Unicode code points in that string.</p>
</div>
<h4>Boolean attributes</h4>
<p>A number of attributes are <dfn title="boolean attribute">boolean
attributes</dfn>. The presence of a boolean attribute on an element
represents the true value, and the absence of the attribute
represents the false value.</p>
<p>If the attribute is present, its value must either be the empty
string or a value that is an <span>ASCII case-insensitive</span>
match for the attribute's canonical name, with no leading or
trailing whitespace.</p>
<p class="note">The values "true" and "false" are not allowed on
boolean attributes. To represent a false value, the attribute has to
be omitted altogether.</p>
<h4>Keywords and enumerated attributes</h4>
<p>Some attributes are defined as taking one of a finite set of
keywords. Such attributes are called <dfn title="enumerated
attribute">enumerated attributes</dfn>. The keywords are each
defined to map to a particular <em>state</em> (several keywords
might map to the same state, in which case some of the keywords are
synonyms of each other; additionally, some of the keywords can be
said to be non-conforming, and are only in the specification for
historical reasons). In addition, two default states can be
given. The first is the <i>invalid value default</i>, the second
is the <i>missing value default</i>.</p>
<p>If an enumerated attribute is specified, the attribute's value
must be an <span>ASCII case-insensitive</span> match for one of the
given keywords that are not said to be non-conforming, with no
leading or trailing whitespace.</p>
<p>When the attribute is specified, if its value is an <span>ASCII
case-insensitive</span> match for one of the given keywords then
that keyword's state is the state that the attribute represents. If
the attribute value matches none of the given keywords, but the
attribute has an <i>invalid value default</i>, then the attribute
represents that state. Otherwise, if the attribute value matches
none of the keywords but there is a <i>missing value default</i>
state defined, then <em>that</em> is the state represented by the
attribute. Otherwise, there is no default, and invalid values must
be ignored.</p>
<p>When the attribute is <em>not</em> specified, if there is a
<i>missing value default</i> state defined, then that is the state
represented by the (missing) attribute. Otherwise, the absence of
the attribute means that there is no state represented.</p>
<p class="note">The empty string can be a valid keyword.</p>
<h4>Numbers</h4>
<h5>Non-negative integers</h5>
<p>A string is a <dfn>valid non-negative integer</dfn> if it
consists of one or more characters in the range U+0030 DIGIT ZERO
(0) to U+0039 DIGIT NINE (9).</p>
<p>A <span>valid non-negative integer</span> represents the number
that is represented in base ten by that string of digits.</p>
<div class="impl">
<p>The <dfn>rules for parsing non-negative integers</dfn> are as
given in the following algorithm. When invoked, the steps must be
followed in the order given, aborting at the first step that returns
a value. This algorithm will return either zero, a positive integer,
or an error. Leading spaces are ignored. Trailing spaces and any
trailing garbage characters are ignored.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</p></li>
<li><p>If the character indicated by <var title="">position</var>
is a U+002B PLUS SIGN character (+), advance <var
title="">position</var> to the next character. (The "<code
title="">+</code>" is ignored, but it is not conforming.)</li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</p></li>
<li><p>If the character indicated by <var title="">position</var>
is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then
return an error.</p></li>
<!-- Ok. At this point we know we have a number. It might have
trailing garbage which we'll ignore, but it's a number, and we
won't return an error. -->
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
resulting sequence as a base-ten integer. Let <var
title="">value</var> be that integer.</p></li>
<li><p>Return <var title="">value</var>.</p></li>
</ol>
</div>
<h5>Signed integers</h5>
<p>A string is a <dfn>valid integer</dfn> if it consists of one or
more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
NINE (9), optionally prefixed with a U+002D HYPHEN-MINUS character
(-).</p>
<p>A <span>valid integer</span> without a U+002D HYPHEN-MINUS (-)
prefix represents the number that is represented in base ten by that
string of digits. A <span>valid integer</span> <em>with</em> a
U+002D HYPHEN-MINUS (-) prefix represents the number represented in
base ten by the string of digits that follows the U+002D
HYPHEN-MINUS, subtracted from zero.</p>
<div class="impl">
<p>The <dfn>rules for parsing integers</dfn> are similar to the
<span title="rules for parsing non-negative integers">rules for
non-negative integers</span>, and are as given in the following
algorithm. When invoked, the steps must be followed in the order
given, aborting at the first step that returns a value. This
algorithm will return either an integer or an error. Leading spaces
are ignored. Trailing spaces and trailing garbage characters are
ignored.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>Let <var title="">sign</var> have the value
"positive".</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</p></li>
<li>
<p>If the character indicated by <var title="">position</var> (the
first character) is a U+002D HYPHEN-MINUS character (-):</p>
<ol>
<li>Let <var title="">sign</var> be "negative".</li>
<li>Advance <var title="">position</var> to the next
character.</li>
<li>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</li>
</ol>
<p>Otherwise, if the character indicated by <var
title="">position</var> (the first character) is a U+002B PLUS
SIGN character (+):</p>
<ol>
<li>Advance <var title="">position</var> to the next
character. (The "<code title="">+</code>" is ignored, but it is
not conforming.)</li>
<li>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</li>
</ol>
</li>
<li><p>If the character indicated by <var title="">position</var>
is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then
return an error.</p></li>
<!-- Ok. At this point we know we have a number. It might have
trailing garbage which we'll ignore, but it's a number, and we
won't return an error. -->
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
resulting sequence as a base-ten integer. Let <var
title="">value</var> be that integer.</p></li>
<li><p>If <var title="">sign</var> is "positive", return <var
title="">value</var>, otherwise return the result of subtracting
<var title="">value</var> from zero.</p></li>
</ol>
</div>
<h5>Real numbers</h5>
<p>A string is a <dfn>valid floating point number</dfn> if it
consists of:</p>
<ol class="brief">
<li>Optionally, a U+002D HYPHEN-MINUS character (-).</li>
<li>A series of one or more characters in the range U+0030 DIGIT
ZERO (0) to U+0039 DIGIT NINE (9).</li>
<li>Optionally:
<ol>
<li>A single U+002E FULL STOP character (.).</li>
<li>A series of one or more characters in the range U+0030 DIGIT
ZERO (0) to U+0039 DIGIT NINE (9).</li>
</ol>
</li>
<li>Optionally:
<ol>
<li>Either a U+0065 LATIN SMALL LETTER E character (e) or a
U+0045 LATIN CAPITAL LETTER E character (E).</li>
<li>Optionally, a U+002D HYPHEN-MINUS character (-) or U+002B
PLUS SIGN character (+).</li>
<li>A series of one or more characters in the range U+0030 DIGIT
ZERO (0) to U+0039 DIGIT NINE (9).</li>
</ol>
</li>
</ol>
<p>A <span>valid floating point number</span> represents the number
obtained by multiplying the significand by ten raised to the power
of the exponent, where the significand is the first number,
interpreted as base ten (including the decimal point and the number
after the decimal point, if any, and interpreting the significand as
a negative number if the whole string starts with a U+002D
HYPHEN-MINUS character (-) and the number is not zero), and where
the exponent is the number after the E, if any (interpreted as a
negative number if there is a U+002D HYPHEN-MINUS character (-)
between the E and the number and the number is not zero, or else
ignoring a U+002B PLUS SIGN character (+) between the E and the
number if there is one). If there is no E, then the exponent is
treated as zero.</p>
<p class="note">The Infinity and Not-a-Number (NaN) values are not
<span title="valid floating point number">valid floating point
numbers</span>.</p>
<div class="impl">
<p>The <dfn title="best representation of the number as a floating
point number">best representation of the number <var
title="">n</var> as a floating point number</dfn> is the string
obtained from applying the JavaScript operator ToString to <var
title="">n</var>. The JavaScript operator ToString is not uniquely
determined. When there are multiple possible strings that could be
obtained from the JavaScript operator ToString for a particular
value, the user agent must always return the same string for that
value (though it may differ from the value used by other user
agents).</p>
<p>The <dfn>rules for parsing floating point number values</dfn> are
as given in the following algorithm. This algorithm must be aborted
at the first step that returns something. This algorithm will return
either a number or an error. Leading spaces are ignored. Trailing
spaces and garbage characters are ignored.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>Let <var title="">value</var> have the value 1.</li>
<li><p>Let <var title="">divisor</var> have the value 1.</p></li>
<li><p>Let <var title="">exponent</var> have the value 1.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</p></li>
<li>
<p>If the character indicated by <var title="">position</var> is a
U+002D HYPHEN-MINUS character (-):</p>
<ol>
<li>Change <var title="">value</var> and <var
title="">divisor</var> to −1.</li>
<li>Advance <var title="">position</var> to the next
character.</li>
<li>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</li>
</ol>
</li>
<li><p>If the character indicated by <var title="">position</var>
is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then
return an error.</p></li>
<!-- Ok. At this point we know we have a number. It might have
trailing garbage which we'll ignore, but it's a number, and we
won't return an error unless it's out of range. -->
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
resulting sequence as a base-ten integer. Multiply <var
title="">value</var> by that integer.</p></li>
<li>If <var title="">position</var> is past the end of <var
title="">input</var>, jump to the step labeled
<i>conversion</i>.</li>
<li><p>If the character indicated by <var title="">position</var>
is a U+002E FULL STOP (.), run these substeps:</p>
<ol>
<li><p>Advance <var title="">position</var> to the next
character.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, or if the character indicated by <var
title="">position</var> is not one of U+0030 DIGIT ZERO (0) to
U+0039 DIGIT NINE (9), then jump to the step labeled
<i>conversion</i>.</li>
<li><p><i>Fraction loop</i>: Multiply <var title="">divisor</var>
by ten.</p></li>
<li>Add the value of the character indicated by <var
title="">position</var>, interpreted as a base-ten digit (0..9)
and divided by <var title="">divisor</var>, to <var
title="">value</var>.</li>
<li><p>Advance <var title="">position</var> to the next
character.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, then jump to the step labeled
<i>conversion</i>.</li>
<li><p>If the character indicated by <var title="">position</var>
is one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), jump
back to the step labeled <i>fraction loop</i> in these
substeps.</p></li>
</ol>
</li>
<li><p>If the character indicated by <var title="">position</var>
is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN
CAPITAL LETTER E character (E), run these substeps:</p>
<ol>
<li><p>Advance <var title="">position</var> to the next
character.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, then jump to the step labeled
<i>conversion</i>.</li>
<li>
<p>If the character indicated by <var title="">position</var> is
a U+002D HYPHEN-MINUS character (-):</p>
<ol>
<li>Change <var title="">exponent</var> to −1.</li>
<li>Advance <var title="">position</var> to the next
character.</li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, then jump to the step labeled
<i>conversion</i>.</li>
</ol>
<p>Otherwise, if the character indicated by <var
title="">position</var> is a U+002B PLUS SIGN character (+):</p>
<ol>
<li>Advance <var title="">position</var> to the next
character.</li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, then jump to the step labeled
<i>conversion</i>.</li>
</ol>
</li>
<li><p>If the character indicated by <var title="">position</var>
is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9),
then jump to the step labeled <i>conversion</i>.</li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
resulting sequence as a base-ten integer. Multiply <var
title="">exponent</var> by that integer.</p></li>
<li><p>Multiply <var title="">value</var> by ten raised to the
<var title="">exponent</var>th power.</p></li>
</ol>
</li>
<li><p><i>Conversion</i>: Let <var title="">S</var> be the set of
finite IEEE 754 single-precision floating point values except
−0, but with two special values added: 2<sup
title="">128</sup> and −2<sup title="">128</sup>.</p></li>
<li><p>Let <var title="">rounded-value</var> be the number in <var
title="">S</var> that is closest to <var title="">value</var>,
selecting the number with an even significand if there are two
equally close values. (The two special values 2<sup
title="">128</sup> and −2<sup title="">128</sup> are
considered to have even significands for this purpose.)</p></li>
<li><p>If <var title="">rounded-value</var> is 2<sup
title="">128</sup> or −2<sup title="">128</sup>, return an
error.</p></li>
<li><p>Return <var title="">rounded-value</var>.</p></li>
</ol>
</div>
<h5>Ratios</h5>
<p class="note">The algorithms described in this section are used by
the <code>progress</code> and <code>meter</code> elements.</p>
<p>A <dfn>valid denominator punctuation character</dfn> is one of
the characters from the table below. There is <dfn title="values
associated with denominator punctuation characters">a value
associated with each denominator punctuation character</dfn>, as
shown in the table below.</p>
<table>
<thead>
<tr>
<th colspan="2">Denominator Punctuation Character</th>
<th>Value</th>
</tr>
</thead>
<tbody>
<tr>
<td>U+0025 PERCENT SIGN</td>
<td>%</td>
<td>100</td>
</tr>
<tr>
<td>U+066A ARABIC PERCENT SIGN</td>
<td>٪</td>
<td>100</td>
</tr>
<tr>
<td>U+FE6A SMALL PERCENT SIGN</td>
<td>﹪</td>
<td>100</td>
</tr>
<tr>
<td>U+FF05 FULLWIDTH PERCENT SIGN</td>
<td>％</td>
<td>100</td>
</tr>
<tr>
<td>U+2030 PER MILLE SIGN</td>
<td>‰</td>
<td>1000</td>
</tr>
<tr>
<td>U+2031 PER TEN THOUSAND SIGN</td>
<td>‱</td>
<td>10000</td>
</tr>
</tbody>
</table>
<div class="impl">
<p>The <dfn>steps for finding one or two numbers of a ratio in a
string</dfn> are as given in the following algorithm. This algorithm
will return either a number, or a number and a denominator
character, or two numbers, or nothing.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, then return nothing and abort these
steps.</p></li>
<li><p><span>Find a number</span> in the string according to the
algorithm below. If this returns a number, let <var
title="">number1</var> be that number. Otherwise, if it returned
nothing or returned an error condition, return nothing and abort
these steps.</p></li>
<li><p><span>Skip White_Space characters</span>.</p></li>
<li><p>If the character indicated by <var title="">position</var>
(if any) is a <span>valid denominator punctuation character</span>,
let <var title="">denominator</var> be that character. Otherwise,
<var title="">denominator</var> has no value.</p></li>
<li><p>If there are any characters in the range U+0030 DIGIT ZERO
(0) to U+0039 DIGIT NINE (9) in <var title="">input</var> at or
after the character indicated by <var title="">position</var> (if
any), but <var title="">denominator</var> has a value, return
nothing and abort these steps.</p></li>
<li><p>Otherwise, if <var title="">denominator</var> has a value,
return <var title="">number1</var> and <var
title="">denominator</var> and abort these steps.</p></li>
<li><p><span>Find a number</span> in the string again. If this
returns a number, let <var title="">number2</var> be that
number. Otherwise, if it returned nothing or an error condition,
return <var title="">number1</var> and abort these steps.</p></li>
<li><p><span>Skip White_Space characters</span>.</p></li>
<li><p>If the character indicated by <var title="">position</var>
(if any) is a <span>valid denominator punctuation character</span>,
return nothing and abort these steps.</li>
<li><p>If there are any characters in the range U+0030 DIGIT ZERO
(0) to U+0039 DIGIT NINE (9) in <var title="">input</var> at or
after the character indicated by <var title="">position</var> (if
any), return nothing and abort these steps.</p></li>
<li>Otherwise, return <var title="">number1</var> and
<var title="">number2</var>.</li>
</ol>
<p>The algorithm to <dfn>find a number</dfn> is as follows. It
returns either nothing, a number, or an error condition.</p>
<ol>
<li><p>Let <var title="">input</var> and <var
title="">position</var> be the same variables as those of the same
name in the algorithm that invoked these steps.</p></li>
<li><p><span>Collect a sequence of characters</span> that are not
U+002E FULL STOP characters (.) and are not characters in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, then return nothing and abort these
steps.</p></li>
<li><p><span>Collect a sequence of characters</span> that are
either U+002E FULL STOP characters (.) or characters in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and let that be
<var title="">s</var>.</p></li>
<li><p>If the first character or the last character of <var
title="">s</var> is a U+002E FULL STOP character (.), or if <var
title="">s</var> contains more than one U+002E FULL STOP character
(.), then return an error condition and abort these steps.</p></li>
<li><p>Parse <var title="">s</var> according to the <span>rules for
parsing floating point number values</span>, to obtain <var
title="">number</var>. This step cannot fail (<var title="">s</var>
is guaranteed to be a <span>valid floating point
number</span>).</p></li>
<li>Return <var title="">number</var>.</li>
</ol>
</div>
<div class="impl">
<h5 id="percentages-and-dimensions">Percentages and lengths</h5>
<!--(percentages are not used in valid html anymore)
<p>A string is a <dfn>valid dimension value</dfn> if it consists of
a character in the range U+0031 DIGIT ONE (1) to U+0039 DIGIT NINE
(9), optionally followed by zero of more characters in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), optionally followed
by a U+002E FULL STOP character (.) and one or more characters in
the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and
optionally suffixed by a U+0025 PERCENT SIGN character (%).</p>
<p>A <span>valid dimension value</span> represents the number that
is represented in base ten by that string of digits, optionally with
a fractional component. If the U+0025 PERCENT SIGN is present, then
the dimension is a percentage; otherwise, it is a length.</p>
<p class="note">For historical reasons, percentanges and lengths
less than 1.0 cannot be represented as <span title="valid dimension
value">valid dimension values</span>.</p>
-->
<p>The <dfn>rules for parsing dimension values</dfn> are as given in
the following algorithm. When invoked, the steps must be followed in
the order given, aborting at the first step that returns a
value. This algorithm will return either a number greater than or
equal to 1.0, or an error; if a number is returned, then it is
further categorized as either a percentage or a length.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</p></li>
<li><p>If the character indicated by <var title="">position</var>
is a U+002B PLUS SIGN character (+), advance <var
title="">position</var> to the next character.</li>
<li><p><span>Collect a sequence of characters</span> that are
U+0030 DIGIT ZERO (0) characters, and discard them.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, return an error.</p></li>
<li><p>If the character indicated by <var title="">position</var>
is not one of U+0031 DIGIT ONE (1) to U+0039 DIGIT NINE (9), then
return an error.</p></li>
<!-- Ok. At this point we know we have a number. It might have
trailing garbage which we'll ignore, but it's a number, and we
won't return an error. -->
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the
resulting sequence as a base-ten integer. Let <var
title="">value</var> be that number.</li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, return <var title="">value</var> as a
length.</p></li>
<li>
<p>If the character indicated by <var title="">position</var> is a
U+002E FULL STOP character (.):</p>
<ol>
<li><p>Advance <var title="">position</var> to the next
character.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, or if the character indicated by <var
title="">position</var> is not one of U+0030 DIGIT ZERO (0) to
U+0039 DIGIT NINE (9), then return <var title="">value</var> as a
length.</li>
<li><p>Let <var title="">divisor</var> have the value 1.</p></li>
<li><p><i>Fraction loop</i>: Multiply <var title="">divisor</var>
by ten.</p></li>
<li>Add the value of the character indicated by <var
title="">position</var>, interpreted as a base-ten digit (0..9)
and divided by <var title="">divisor</var>, to <var
title="">value</var>.</li>
<li><p>Advance <var title="">position</var> to the next
character.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, then return <var title="">value</var> as a
length.</li>
<li><p>If the character indicated by <var title="">position</var>
is one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), return
to the step labeled <i>fraction loop</i> in these
substeps.</p></li>
</ol>
</li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, return <var title="">value</var> as a
length.</p></li>
<li><p>If the character indicated by <var title="">position</var>
is a U+0025 PERCENT SIGN character (%), return <var
title="">value</var> as a percentage.</p></li>
<li><p>Return <var title="">value</var> as a length.</p></li>
</ol>
</div>
<h5>Lists of integers</h5>
<p>A <dfn>valid list of integers</dfn> is a number of <span
title="valid integer">valid integers</span> separated by U+002C
COMMA characters, with no other characters (e.g. no <span
title="space character">space characters</span>). In addition, there
might be restrictions on the number of integers that can be given,
or on the range of values allowed.</p>
<div class="impl">
<p>The <dfn>rules for parsing a list of integers</dfn> are as
follows:</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>Let <var title="">numbers</var> be an initially empty list
of integers. This list will be the result of this
algorithm.</p></li>
<li><p>If there is a character in the string <var
title="">input</var> at position <var title="">position</var>, and
it is either a U+0020 SPACE, U+002C COMMA, or U+003B SEMICOLON
character, then advance <var title="">position</var> to the next
character in <var title="">input</var>, or to beyond the end of the
string if there are no more characters.</p></li>
<li><p>If <var title="">position</var> points to beyond the end of
<var title="">input</var>, return <var title="">numbers</var> and
abort.</p></li>
<li><p>If the character in the string <var title="">input</var> at
position <var title="">position</var> is a U+0020 SPACE, U+002C
COMMA, or U+003B SEMICOLON character, then return to step 4.</li>
<li><p>Let <var title="">negated</var> be false.</p></li>
<li><p>Let <var title="">value</var> be 0.</p></li>
<li><p>Let <var title="">started</var> be false. This variable is
set to true when the parser sees a number or a U+002D HYPHEN-MINUS
character (-).</p></li>
<li><p>Let <var title="">got number</var> be false. This variable
is set to true when the parser sees a number.</p></li>
<li><p>Let <var title="">finished</var> be false. This variable is
set to true to switch parser into a mode where it ignores
characters until the next separator.</p></li>
<li><p>Let <var title="">bogus</var> be false.</p></li>
<li><p><i>Parser</i>: If the character in the string <var
title="">input</var> at position <var title="">position</var>
is:</p>
<dl class="switch">
<dt>A U+002D HYPHEN-MINUS character</dt>
<dd>
<p>Follow these substeps:</p>
<ol>
<li>If <var title="">got number</var> is true, let <var
title="">finished</var> be true.</li>
<li>If <var title="">finished</var> is true, skip to the next
step in the overall set of steps.</li>
<li>If <var title="">started</var> is true, let <var
title="">negated</var> be false.</li>
<li>Otherwise, if <var title="">started</var> is false and if <var
title="">bogus</var> is false, let <var title="">negated</var>
be true.</li>
<li>Let <var title="">started</var> be true.</li>
</ol>
</dd>
<dt>A character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
NINE (9)</dt>
<dd>
<p>Follow these substeps:</p>
<ol>
<li>If <var title="">finished</var> is true, skip to the next
step in the overall set of steps.</li>
<li>Multiply <var title="">value</var> by ten.</li>
<li>Add the value of the digit, interpreted in base ten, to
<var title="">value</var>.</li>
<li>Let <var title="">started</var> be true.</li>
<li>Let <var title="">got number</var> be true.</li>
</ol>
</dd>
<dt>A U+0020 SPACE character</dt>
<dt>A U+002C COMMA character</dt>
<dt>A U+003B SEMICOLON character</dt>
<dd>
<p>Follow these substeps:</p>
<ol>
<li>If <var title="">got number</var> is false, return the <var
title="">numbers</var> list and abort. This happens if an entry
in the list has no digits, as in "<code
title="">1,2,x,4</code>".</li>
<li>If <var title="">negated</var> is true, then negate <var
title="">value</var>.</li>
<li>Append <var title="">value</var> to the <var
title="">numbers</var> list.</li>
<li>Jump to step 4 in the overall set of steps.</li>
</ol>
</dd>
<!-- <dt>A U+002E FULL STOP character</dt> -->
<dt>A character in the range U+0001 to U+001F, <!-- space --> U+0021 to U+002B, <!-- comma --> U+002D to U+002F, <!-- digits --> U+003A, <!-- semicolon --> U+003C to U+0040, <!-- a-z --> U+005B to U+0060, <!-- A-Z --> U+007b to U+007F
(i.e. any other non-alphabetic ASCII character)</dt>
<!--
Test: http://www.hixie.ch/tests/adhoc/html/flow/image-maps/004-demo.html
IE6 on Wine treats the following characters like this also: U+1-U+1f,
U+21-U+2b, U+2d-U+2f, U+3a, U+3c-U+40, U+5b-U+60, U+7b-U+82,
U+84-U+89, U+8b, U+8d, U+8f-U+99, U+9b, U+9d, U+a0-U+bf, U+d7, U+f7,
U+1f6-U+1f9, U+218-U+24f, U+2a9-U+385, U+387, U+38b, U+38d, U+3a2,
U+3cf, U+3d7-U+3d9, U+3db, U+3dd, U+3df, U+3e1, U+3f4-U+400, U+40d,
U+450, U+45d, U+482-U+48f, U+4c5-U+4c6, U+4c9-U+4ca, U+4cd-U+4cf,
U+4ec-U+4ed, U+4f6-U+4f7, U+4fa-U+530, U+557-U+560, U+588-U+5cf,
U+5eb-U+5ef, U+5f3-U+620, U+63b-U+640, U+64b-U+670, U+6b8-U+6b9,
U+6bf, U+6cf, U+6d4, U+6d6-U+904, U+93a-U+957, U+962-U+984,
U+98d-U+98e, U+991-U+992, U+9a9, U+9b1, U+9b3-U+9b5, U+9ba-U+9db,
U+9de, U+9e2-U+9ef, U+9f2-U+a04, U+a0b-U+a0e, U+a11-U+a12, U+a29,
U+a31, U+a34, U+a37, U+a3a-U+a58, U+a5d, U+a5f-U+a84, U+a8c, U+a8e,
U+a92, U+aa9, U+ab1, U+ab4, U+aba-U+adf, U+ae1-U+b04, U+b0d-U+b0e,
U+b11-U+b12, U+b29, U+b31, U+b34-U+b35, U+b3a-U+b5b, U+b5e,
U+b62-U+b84, U+b8b-U+b8d, U+b91, U+b96-U+b98, U+b9b, U+b9d,
U+ba0-U+ba2, U+ba5-U+ba7, U+bab-U+bad, U+bb6, U+bba-U+c04, U+c0d,
U+c11, U+c29, U+c34, U+c3a-U+c5f, U+c62-U+c84, U+c8d, U+c91, U+ca9,
U+cb4, U+cba-U+cdd, U+cdf, U+ce2-U+d04, U+d0d, U+d11, U+d29,
U+d3a-U+d5f, U+d62-U+e00, U+e2f, U+e31, U+e34-U+e3f, U+e46-U+e80,
U+e83, U+e85-U+e86, U+e89, U+e8b-U+e8c, U+e8e-U+e93, U+e98, U+ea0,
U+ea4, U+ea6, U+ea8-U+ea9, U+eac, U+eaf-U+edb, U+ede-U+109f,
U+10c6-U+10cf, U+10f7-U+10ff, U+115a-U+115e, U+11a3-U+11a7,
U+11fa-U+1dff, U+1e9b-U+1e9f, U+1efa-U+1eff, U+1f16-U+1f17,
U+1f1e-U+1f1f, U+1f46-U+1f47, U+1f4e-U+1f4f, U+1f58, U+1f5a, U+1f5c,
U+1f5e, U+1f7e-U+1f7f, U+1fb5, U+1fbd-U+1fc1, U+1fc5, U+1fcd-U+1fcf,
U+1fd4-U+1fd5, U+1fdc-U+1fdf, U+1fed-U+1ff1, U+1ff5, U+1ffd-U+249b,
U+24ea-U+3004, U+3006-U+3040, U+3095-U+309a, U+309f-U+30a0, U+30fb,
U+30ff-U+3104, U+312d-U+3130, U+318f-U+4dff, U+9fa6-U+abff,
U+d7a4-U+d7ff, U+e000-U+f8ff, U+fa2e-U+faff, U+fb07-U+fb12,
U+fb18-U+fb1e, U+fb37, U+fb3d, U+fb3f, U+fb42, U+fb45, U+fbb2-U+fbd2,
U+fbe9, U+fce1, U+fd3e-U+fd4f, U+fd90-U+fd91, U+fdc8-U+fdef,
U+fdfc-U+fe7f, U+fefd-U+ff20, U+ff3b-U+ff40, U+ff5b-U+ff65, U+ffa0,
U+ffbf-U+ffc1, U+ffc8-U+ffc9, U+ffd0-U+ffd1, U+ffd8-U+ffd9,
U+ffdd-U+ffff
IE7 on Win2003 treats the following characters like this also
instead: U+1-U+1f, U+21-U+2b, U+2d-U+2f, U+3a, U+3c-U+40, U+5b-U+60,
U+7b-U+82, U+84-U+89, U+8b, U+8d, U+8f-U+99, U+9b, U+9d, U+a0-U+a9,
U+ab-U+b4, U+b6-U+b9, U+bb-U+bf, U+d7, U+f7, U+220-U+221,
U+234-U+24f, U+2ae-U+2af, U+2b9-U+2ba, U+2c2-U+2df, U+2e5-U+2ed,
U+2ef-U+344, U+346-U+379, U+37b-U+385, U+387, U+38b, U+38d, U+3a2,
U+3cf, U+3d8-U+3d9, U+3f4-U+3ff, U+482-U+48b, U+4c5-U+4c6,
U+4c9-U+4ca, U+4cd-U+4cf, U+4f6-U+4f7, U+4fa-U+530, U+557-U+558,
U+55a-U+560, U+588-U+5cf, U+5eb-U+5ef, U+5f3-U+620, U+63b-U+640,
U+656-U+66f, U+6d4, U+6dd-U+6e0, U+6e9-U+6ec, U+6ee-U+6f9,
U+6fd-U+70f, U+72d-U+72f, U+740-U+77f, U+7b1-U+900, U+904,
U+93a-U+93c, U+94d - U+94f, U+951-U+957, U+964-U+980, U+984,
U+98d-U+98e, U+991-U+992, U+9a9, U+9b1, U+9b3-U+9b5, U+9ba-U+9bd,
U+9c5-U+9c6, U+9c9-U+9ca, U+9cd-U+9d6, U+9d8-U+9db, U+9de,
U+9e4-U+9ef, U+9f2-U+a01, U+a03-U+a04, U+a0b-U+a0e, U+a11-U+a12,
U+a29, U+a31, U+a34, U+a37, U+a3a-U+a3d, U+a43-U+a46, U+a49-U+a4a,
U+a4d-U+a58, U+a5d, U+a5f-U+a6f, U+a75-U+a80, U+a84, U+a8c, U+a8e,
U+a92, U+aa9, U+ab1, U+ab4, U+aba-U+abc, U+ac6, U+aca, U+acd-U+acf,
U+ad1-U+adf, U+ae1-U+b00, U+b04, U+b0d-U+b0e, U+b11-U+b12, U+b29,
U+b31, U+b34-U+b35, U+b3a-U+b3c, U+b44-U+b46, U+b49 - U+b4a,
U+b4d-U+b55, U+b58-U+b5b, U+b5e, U+b62-U+b81, U+b84, U+b8b-U+b8d,
U+b91, U+b96-U+b98, U+b9b, U+b9d, U+ba0 - U+ba2, U+ba5-U+ba7,
U+bab-U+bad, U+bb6, U+bba-U+bbd, U+bc3-U+bc5, U+bc9, U+bcd-U+bd6,
U+bd8-U+c00, U+c04, U+c0d, U+c11, U+c29, U+c34, U+c3a-U+c3d, U+c45,
U+c49, U+c4d-U+c54, U+c57-U+c5f, U+c62-U+c81, U+c84, U+c8d, U+c91,
U+ca9, U+cb4, U+cba-U+cbd, U+cc5, U+cc9, U+ccd-U+cd4, U+cd7-U+cdd,
U+cdf, U+ce2-U+d01, U+d04, U+d0d, U+d11, U+d29, U+d3a-U+d3d,
U+d44-U+d45, U+d49, U+d4d-U+d56, U+d58-U+d5f, U+d62-U+d81, U+d84,
U+d97-U+d99, U+db2, U+dbc, U+dbe - U+dbf, U+dc7-U+dce, U+dd5, U+dd7,
U+de0-U+df1, U+df4-U+e00, U+e3b-U+e3f, U+e4f-U+e80, U+e83,
U+e85-U+e86, U+e89, U+e8b-U+e8c, U+e8e-U+e93, U+e98, U+ea0, U+ea4,
U+ea6, U+ea8-U+ea9, U+eac, U+eba, U+ebe-U+ebf, U+ec5-U+ecc,
U+ece-U+edb, U+ede-U+eff, U+f01-U+f3f, U+f48, U+f6b-U+f70,
U+f82-U+f87, U+f8c-U+f8f, U+f98, U+fbd-U+fff, U+1022, U+1028, U+102b,
U+1033-U+1035, U+1037, U+1039-U+104f, U+105a-U+109f, U+10c6-U+10cf,
U+10f7-U+10ff, U+115a - U+115e, U+11a3-U+11a7, U+11fa-U+11ff, U+1207,
U+1247, U+1249, U+124e-U+124f, U+1257, U+1259, U+125e-U+125f, U+1287,
U+1289, U+128e-U+128f, U+12af, U+12b1, U+12b6-U+12b7, U+12bf, U+12c1,
U+12c6-U+12c7, U+12cf, U+12d7, U+12ef, U+130f, U+1311, U+1316-U+1317,
U+131f, U+1347, U+135b-U+139f, U+13f5-U+1400, U+166d-U+166e,
U+1677-U+1680, U+169b - U+169f, U+16eb-U+177f, U+17c9-U+181f, U+1843,
U+1878-U+187f, U+18aa-U+1dff, U+1e9c-U+1e9f, U+1efa-U+1eff,
U+1f16-U+1f17, U+1f1e-U+1f1f, U+1f46-U+1f47, U+1f4e-U+1f4f, U+1f58,
U+1f5a, U+1f5c, U+1f5e, U+1f7e-U+1f7f, U+1fb5, U+1fbd, U+1fbf-U+1fc1,
U+1fc5, U+1fcd-U+1fcf, U+1fd4-U+1fd5, U+1fdc-U+1fdf, U+1fed-U+1ff1,
U+1ff5, U+1ffd-U+207e, U+2080-U+2101, U+2103-U+2106, U+2108-U+2109,
U+2114, U+2116-U+2118, U+211e-U+2123, U+2125, U+2127, U+2129, U+212e,
U+2132, U+213a-U+215f, U+2184-U+3005, U+3008-U+3020, U+302a-U+3037,
U+303b-U+3104, U+312d-U+3130, U+318f - U+319f, U+31b8-U+33ff,
U+4db6-U+4dff, U+9fa6-U+9fff, U+a48d-U+abff, U+d7a4-U+d7ff,
U+e000-U+f8ff, U+fa2e-U+faff, U+fb07-U+fb12, U+fb18-U+fb1c, U+fb1e,
U+fb29, U+fb37, U+fb3d, U+fb3f, U+fb42, U+fb45, U+fbb2-U+fbd2,
U+fd3e-U+fd4f, U+fd90-U+fd91, U+fdc8-U+fdef, U+fdfc-U+fe6f, U+fe73,
U+fe75, U+fefd-U+ff20, U+ff3b-U+ff40, U+ff5b-U+ff9f, U+ffbf-U+ffc1,
U+ffc8-U+ffc9, U+ffd0-U+ffd1, U+ffd8-U+ffd9, U+ffdd-U+ffff
-->
<dd>
<p>Follow these substeps:</p>
<ol>
<li>If <var title="">got number</var> is true, let <var
title="">finished</var> be true.</li>
<li>If <var title="">finished</var> is true, skip to the next
step in the overall set of steps.</li>
<li>Let <var title="">negated</var> be false.</li>
</ol>
</dd>
<dt>Any other character</dt>
<!-- alphabetic a-z A-Z, and non-ASCII -->
<dd>
<p>Follow these substeps:</p>
<ol>
<li>If <var title="">finished</var> is true, skip to the next
step in the overall set of steps.</li>
<li>Let <var title="">negated</var> be false.</li>
<li>Let <var title="">bogus</var> be true.</li>
<li>If <var title="">started</var> is true, then return the
<var title="">numbers</var> list, and abort. (The value in <var
title="">value</var> is not appended to the list first; it is
dropped.)</li>
</ol>
</dd>
</dl>
</li>
<li><p>Advance <var title="">position</var> to the next character
in <var title="">input</var>, or to beyond the end of the string if
there are no more characters.</p></li>
<li><p>If <var title="">position</var> points to a character (and
not to beyond the end of <var title="">input</var>), jump to the
big <i>Parser</i> step above.</p></li>
<li><p>If <var title="">negated</var> is true, then negate <var
title="">value</var>.</li>
<li><p>If <var title="">got number</var> is true, then append <var
title="">value</var> to the <var title="">numbers</var> list.</li>
<li><p>Return the <var title="">numbers</var> list and
abort.</p></li>
</ol>
</div>
<div class="impl">
<h5>Lists of dimensions</h5>
<!-- no definition of a type since no conforming feature uses this
syntax (it's only used in cols="" and rows="" on <frameset> -->
<p>The <dfn>rules for parsing a list of dimensions</dfn> are as
follows. These rules return a list of zero or more pairs consisting
of a number and a unit, the unit being one of <i>percentage</i>,
<i>relative</i>, and <i>absolute</i>.</p>
<ol>
<li><p>Let <var title="">raw input</var> be the string being
parsed.</p></li>
<li><p>If the last character in <var title="">raw input</var> is a
U+002C COMMA character (,), then remove that character from <var
title="">raw input</var>.</p></li>
<li><p><span title="split a string on commas">Split the string <var
title="">raw input</var> on commas</span>. Let <var title="">raw
tokens</var> be the resulting list of tokens.</p></li>
<li><p>Let <var title="">result</var> be an empty list of
number/unit pairs.</p></li>
<li>
<p>For each token in <var title="">raw tokens</var>, run the
following substeps:</p>
<ol>
<li><p>Let <var title="">input</var> be the token.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>Let <var title="">value</var> be the number 0.</p></li>
<li><p>Let <var title="">unit</var> be <i>absolute</i>.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, set <var title="">unit</var> to
<i>relative</i> and jump to the last substep.</p></li>
<li><p>If the character at <var title="">position</var> is a
character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE
(9), <span>collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), interpret the
resulting sequence as an integer in base ten, and increment <var
title="">value</var> by that integer.</p></li>
<li>
<p>If the character at <var title="">position</var> is a U+002E
FULL STOP character (.), run these substeps:</p>
<ol>
<li><p><span>Collect a sequence of characters</span> consisting
of <span title="space character">space characters</span> and
characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
NINE (9). Let <var title="">s</var> be the resulting
sequence.</p></li>
<li><p>Remove all <span title="space character">space
characters</span> in <var title="">s</var>.</p></li>
<li>
<p>If <var title="">s</var> is not the empty string, run these
subsubsteps:</p>
<ol>
<li><p>Let <var title="">length</var> be the number of
characters in <var title="">s</var> (after the spaces were
removed).</p></li>
<li><p>Let <var title="">fraction</var> be the result of
interpreting <var title="">s</var> as a base-ten integer, and
then dividing that number by <span title="">10<sup
title=""><var title="">length</var></sup></span>.</li>
<li><p>Increment <var title="">value</var> by <var
title="">fraction</var>.</p></li>
</ol>
</li>
</ol>
</li>
<li><p><span>Skip whitespace</span>.</p></li>
<li>
<p>If the character at <var title="">position</var> is a U+0025
PERCENT SIGN character (%), then set <var title="">unit</var> to
<i>percentage</i>.</p>
<p>Otherwise, if the character at <var title="">position</var>
is a U+002A ASTERISK character (*), then set <var
title="">unit</var> to <i>relative</i>.</p>
</li>
<!-- the remaining characters in /input/ are ignored -->
<li><p>Add an entry to <var title="">result</var> consisting of
the number given by <var title="">value</var> and the unit given
by <var title="">unit</var>.</p></li>
</ol>
</li>
<li><p>Return the list <var title="">result</var>.</p></li>
</ol>
</div>
<h4>Dates and times</h4>
<p>In the algorithms below, the <dfn>number of days in month <var
title="">month</var> of year <var title="">year</var></dfn> is:
<em>31</em> if <var title="">month</var> is 1, 3, 5, 7, 8, 10, or
12; <em>30</em> if <var title="">month</var> is 4, 6, 9, or 11;
<em>29</em> if <var title="">month</var> is 2 and <var
title="">year</var> is a number divisible by 400, or if <var
title="">year</var> is a number divisible by 4 but not by 100; and
<em>28</em> otherwise. This takes into account leap years in the
Gregorian calendar. <a
href="#refsGREGORIAN">[GREGORIAN]</a></p>
<p>The <dfn title="concept-datetime-digit">digits</dfn> in the date
and time syntaxes defined in this section must be characters in the
range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), used to
express numbers in base ten.</p>
<div class="impl">
<p class="note">While the formats described here are intended to be
subsets of the corresponding ISO8601 formats, this specification
defines parsing rules in much more detail than ISO8601.
Implementors are therefore encouraged to carefully examine any date
parsing libraries before using them to implement the parsing rules
described below; ISO8601 libraries might not parse dates and times
in exactly the same manner. <a href="#refsISO8601">[ISO8601]</a></p>
</div>
<h5>Months</h5>
<p>A <dfn title="concept-month">month</dfn> consists of a specific
proleptic Gregorian date with no time-zone information and no date
information beyond a year and a month. <a
href="#refsGREGORIAN">[GREGORIAN]</a></p>
<p>A string is a <dfn>valid month string</dfn> representing a year
<var title="">year</var> and month <var title="">month</var> if it
consists of the following components in the given order:</p>
<ol>
<li>Four or more <span
title="concept-datetime-digit">digits</span>, representing <var
title="">year</var>, where <var
title="">year</var> > 0</li>
<li>A U+002D HYPHEN-MINUS character (-)</li>
<li>Two <span title="concept-datetime-digit">digits</span>,
representing the month <var title="">month</var>, in the range
1 ≤ <var
title="">month</var> ≤ 12</li>
</ol>
<div class="impl">
<p>The rules to <dfn>parse a month string</dfn> are as follows. This
will return either a year and month, or nothing. If at any point the
algorithm says that it "fails", this means that it is aborted at
that point and returns nothing.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Parse a month component</span> to obtain <var
title="">year</var> and <var title="">month</var>. If this returns
nothing, then fail.</p>
<li><p>If <var title="">position</var> is <em>not</em> beyond the
end of <var title="">input</var>, then fail.</p></li>
<li><p>Return <var title="">year</var> and <var
title="">month</var>.</p></li>
</ol>
<p>The rules to <dfn>parse a month component</dfn>, given an <var
title="">input</var> string and a <var title="">position</var>, are
as follows. This will return either a year and a month, or
nothing. If at any point the algorithm says that it "fails", this
means that it is aborted at that point and returns nothing.</p>
<ol>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not at least four characters long, then
fail. Otherwise, interpret the resulting sequence as a base-ten
integer. Let that number be the <var title="">year</var>.</p></li>
<li><p>If <var title="">year</var> is not a number greater than
zero, then fail.</p></li>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var> or if the character at <var
title="">position</var> is not a U+002D HYPHEN-MINUS character,
then fail. Otherwise, move <var title="">position</var> forwards
one character.</p></li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not exactly two characters long, then fail. Otherwise,
interpret the resulting sequence as a base-ten integer. Let that
number be the <var title="">month</var>.</p></li>
<li><p>If <var title="">month</var> is not a number in the range
1 ≤ <var title="">month</var> ≤ 12, then
fail.</p></li>
<li><p>Return <var title="">year</var> and <var
title="">month</var>.</p></li>
</ol>
</div>
<h5>Dates</h5>
<p>A <dfn title="concept-date">date</dfn> consists of a specific
proleptic Gregorian date with no time-zone information, consisting
of a year, a month, and a day. <a
href="#refsGREGORIAN">[GREGORIAN]</a></p>
<p>A string is a <dfn>valid date string</dfn> representing a year
<var title="">year</var>, month <var title="">month</var>, and day
<var title="">day</var> if it consists of the following components
in the given order:</p>
<ol>
<li>A <span>valid month string</span>, representing <var
title="">year</var> and <var title="">month</var></li>
<li>A U+002D HYPHEN-MINUS character (-)</li>
<li>Two <span title="concept-datetime-digit">digits</span>,
representing <var title="">day</var>, in the range
1 ≤ <var title="">day</var> ≤ <var
title="">maxday</var> where <var title="">maxday</var> is the <span
title="number of days in month month of year year">number of days
in the month <var title="">month</var> and year <var
title="">year</var></span></li>
</ol>
<div class="impl">
<p>The rules to <dfn>parse a date string</dfn> are as follows. This
will return either a date, or nothing. If at any point the algorithm
says that it "fails", this means that it is aborted at that point
and returns nothing.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Parse a date component</span> to obtain <var
title="">year</var>, <var title="">month</var>, and <var
title="">day</var>. If this returns nothing, then fail.</p>
<li><p>If <var title="">position</var> is <em>not</em> beyond the
end of <var title="">input</var>, then fail.</p></li>
<li><p>Let <var title="">date</var> be the date with year <var
title="">year</var>, month <var title="">month</var>, and day <var
title="">day</var>.</p></li>
<li><p>Return <var title="">date</var>.</p></li>
</ol>
<p>The rules to <dfn>parse a date component</dfn>, given an <var
title="">input</var> string and a <var title="">position</var>, are
as follows. This will return either a year, a month, and a day, or
nothing. If at any point the algorithm says that it "fails", this
means that it is aborted at that point and returns nothing.</p>
<ol>
<li><p><span>Parse a month component</span> to obtain <var
title="">year</var> and <var title="">month</var>. If this returns
nothing, then fail.</li>
<li><p>Let <var title="">maxday</var> be the <span>number of days
in month <var title="">month</var> of year <var
title="">year</var></span>.</p></li>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var> or if the character at <var
title="">position</var> is not a U+002D HYPHEN-MINUS character,
then fail. Otherwise, move <var title="">position</var> forwards
one character.</p></li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not exactly two characters long, then fail. Otherwise,
interpret the resulting sequence as a base-ten integer. Let that
number be the <var title="">day</var>.</p></li>
<li><p>If <var title="">day</var> is not a number in the range
1 ≤ <var title="">day</var> ≤ <var
title="">maxday</var>, then fail.</li>
<li><p>Return <var title="">year</var>, <var title="">month</var>,
and <var title="">day</var>.</p></li>
</ol>
</div>
<h5>Times</h5>
<p>A <dfn title="concept-time">time</dfn> consists of a specific
time with no time-zone information, consisting of an hour, a minute,
a second, and a fraction of a second.</p>
<p>A string is a <dfn>valid time string</dfn> representing an hour
<var title="">hour</var>, a minute <var title="">minute</var>, and a
second <var title="">second</var> if it consists of the following
components in the given order:</p>
<ol>
<li>Two <span title="concept-datetime-digit">digits</span>,
representing <var title="">hour</var>, in the range
0 ≤ <var title="">hour</var> ≤ 23</li>
<li>A U+003A COLON character (:)</li>
<li>Two <span title="concept-datetime-digit">digits</span>,
representing <var title="">minute</var>, in the range
0 ≤ <var title="">minute</var> ≤ 59</li>
<li>Optionally (required if <var title="">second</var> is
non-zero):
<ol>
<li>A U+003A COLON character (:)</li>
<li>Two <span title="concept-datetime-digit">digits</span>,
representing the integer part of <var title="">second</var>, in
the range 0 ≤ <var
title="">s</var> ≤ 59</li>
<li>Optionally (required if <var title="">second</var> is not an
integer):
<ol>
<li>A 002E FULL STOP character (.)</li>
<li>One or more <span
title="concept-datetime-digit">digits</span>, representing the
fractional part of <var title="">second</var></li>
</ol>
</li>
</ol>
</li>
</ol>
<p class="note">The <var title="">second</var> component cannot be
60 or 61; leap seconds cannot be represented.</p>
<div class="impl">
<p>The rules to <dfn>parse a time string</dfn> are as follows. This
will return either a time, or nothing. If at any point the algorithm
says that it "fails", this means that it is aborted at that point
and returns nothing.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Parse a time component</span> to obtain <var
title="">hour</var>, <var title="">minute</var>, and <var
title="">second</var>. If this returns nothing, then fail.</p>
<li><p>If <var title="">position</var> is <em>not</em> beyond the
end of <var title="">input</var>, then fail.</p></li>
<li><p>Let <var title="">time</var> be the time with hour <var
title="">hour</var>, minute <var title="">minute</var>, and second
<var title="">second</var>.</p></li>
<li><p>Return <var title="">time</var>.</p></li>
</ol>
<p>The rules to <dfn>parse a time component</dfn>, given an <var
title="">input</var> string and a <var title="">position</var>, are
as follows. This will return either an hour, a minute, and a second,
or nothing. If at any point the algorithm says that it "fails", this
means that it is aborted at that point and returns nothing.</p>
<ol>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not exactly two characters long, then fail. Otherwise,
interpret the resulting sequence as a base-ten integer. Let that
number be the <var title="">hour</var>.</p></li>
<li>If <var title="">hour</var> is not a number in the range
0 ≤ <var title="">hour</var> ≤ 23, then
fail.</li>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var> or if the character at <var
title="">position</var> is not a U+003A COLON character, then
fail. Otherwise, move <var title="">position</var> forwards one
character.</p></li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not exactly two characters long, then fail. Otherwise,
interpret the resulting sequence as a base-ten integer. Let that
number be the <var title="">minute</var>.</p></li>
<li>If <var title="">minute</var> is not a number in the range
0 ≤ <var title="">minute</var> ≤ 59, then
fail.</li>
<li><p>Let <var title="">second</var> be a string with the value
"0".</p></li>
<li>
<p>If <var title="">position</var> is not beyond the end of
<var title="">input</var> and the character at <var
title="">position</var> is a U+003A COLON, then run these
substeps:</p>
<ol>
<li><p>Advance <var title="">position</var> to the next character
in <var title="">input</var>.</p></li>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var>, or at the last character in <var
title="">input</var>, or if the next <em>two</em> characters in
<var title="">input</var> starting at <var
title="">position</var> are not two characters both in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then
fail.</p></li>
<li><p><span>Collect a sequence of characters</span> that are
either characters in the range U+0030 DIGIT ZERO (0) to U+0039
DIGIT NINE (9) or U+002E FULL STOP characters. If the collected
sequence has more than one U+002E FULL STOP characters, or if the
last character in the sequence is a U+002E FULL STOP character,
then fail. Otherwise, let the collected string be <var
title="">second</var> instead of its previous value.</p></li>
</ol>
</li>
<li><p>Interpret <var title="">second</var> as a base-ten number
(possibly with a fractional part). Let <var title="">second</var>
be that number instead of the string version.</p></li>
<li><p>If <var title="">second</var> is not a number in the range
0 ≤ <var title="">second</var> < 60, then
fail.</p></li>
<li><p>Return <var title="">hour</var>, <var title="">minute</var>,
and <var title="">second</var>.</p></li>
</ol>
</div>
<h5>Local dates and times</h5>
<p>A <dfn title="concept-datetime-local">local date and time</dfn>
consists of a specific proleptic Gregorian date, consisting of a
year, a month, and a day, and a time, consisting of an hour, a
minute, a second, and a fraction of a second, but expressed without
a time zone. <a href="#refsGREGORIAN">[GREGORIAN]</a></p>
<p>A string is a <dfn>valid local date and time string</dfn>
representing a date and time if it consists of the following
components in the given order:</p>
<ol>
<li>A <span>valid date string</span> representing the date.</li>
<li>A U+0054 LATIN CAPITAL LETTER T character (T).</li>
<li>A <span>valid time string</span> representing the time.</li>
</ol>
<div class="impl">
<p>The rules to <dfn>parse a local date and time string</dfn> are as
follows. This will return either a date and time, or nothing. If at
any point the algorithm says that it "fails", this means that it is
aborted at that point and returns nothing.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Parse a date component</span> to obtain <var
title="">year</var>, <var title="">month</var>, and <var
title="">day</var>. If this returns nothing, then fail.</p>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var> or if the character at <var
title="">position</var> is not a U+0054 LATIN CAPITAL LETTER T
character (T) then fail. Otherwise, move <var
title="">position</var> forwards one character.</p></li>
<li><p><span>Parse a time component</span> to obtain <var
title="">hour</var>, <var title="">minute</var>, and <var
title="">second</var>. If this returns nothing, then fail.</p>
<li><p>If <var title="">position</var> is <em>not</em> beyond the
end of <var title="">input</var>, then fail.</p></li>
<li><p>Let <var title="">date</var> be the date with year <var
title="">year</var>, month <var title="">month</var>, and day <var
title="">day</var>.</p></li>
<li><p>Let <var title="">time</var> be the time with hour <var
title="">hour</var>, minute <var title="">minute</var>, and second
<var title="">second</var>.</p></li>
<li><p>Return <var title="">date</var> and <var
title="">time</var>.</p></li>
</ol>
</div>
<h5>Global dates and times</h5>
<p>A <dfn title="concept-datetime">global date and time</dfn>
consists of a specific proleptic Gregorian date, consisting of a
year, a month, and a day, and a time, consisting of an hour, a
minute, a second, and a fraction of a second, expressed with a
time-zone offset, consisting of a signed number of hours and
minutes. <a href="#refsGREGORIAN">[GREGORIAN]</a></p>
<p>A string is a <dfn>valid global date and time string</dfn>
representing a date, time, and a time-zone offset if it consists of
the following components in the given order:</p>
<ol>
<li>A <span>valid date string</span> representing the date</li>
<li>A U+0054 LATIN CAPITAL LETTER T character (T)</li>
<li>A <span>valid time string</span> representing the time</li>
<li>Either:
<ul>
<li>A U+005A LATIN CAPITAL LETTER Z character (Z), allowed only
if the time zone is UTC</li>
<li>Or:
<ol>
<li>Either a U+002B PLUS SIGN character (+) or a U+002D
HYPHEN-MINUS character (-), representing the sign of the
time-zone offset</li>
<li>Two <span title="concept-datetime-digit">digits</span>,
representing the hours component <var title="">hour</var> of
the time-zone offset, in the range 0 ≤ <var
title="">hour</var> ≤ 23</li>
<li>A U+003A COLON character (:)</li>
<li>Two <span title="concept-datetime-digit">digits</span>,
representing the minutes component <var title="">minute</var>
of the time-zone offset, in the range 0 ≤ <var
title="">minute</var> ≤ 59</li>
</ol>
</li>
</ul>
</li>
</ol>
<p class="note">This format allows for time-zone offsets from -23:59
to +23:59. In practice, however, the range of offsets of actual time
zones is -12:00 to +14:00, and the minutes component of offsets of
actual time zones is always either 00, 30, or 45.</p>
<div class="example">
<p>The following are some examples of dates written as <span
title="valid global date and time string">valid global date and
time strings</span>.</p>
<dl>
<dt>"<code>0037-12-13T00:00Z</code>"</dt>
<dd>Midnight UTC on the birthday of Nero (the Roman Emperor).</dd>
<dt>"<code>1979-10-14T12:00:00.001-04:00</code>"</dt>
<dd>One millisecond after noon on October 14th 1979, in the time
zone in use on the east coast of the USA during daylight saving
time.</dd>
<dt>"<code>8592-01-01T02:09+02:09</code>"</dt>
<dd>Midnight UTC on the 1st of January, 8592. The time zone
associated with that time is two hours and nine minutes ahead of
UTC, which is not currently a real time zone, but is nonetheless
allowed.</dd>
</dl>
<p>Several things are notable about these dates:</p>
<ul>
<li>Years with fewer than four digits have to be
zero-padded. The date "37-12-13" would not be a valid date.</li>
<li>To unambiguously identify a moment in time prior to the
introduction of the Gregorian calendar, the date has to be first
converted to the Gregorian calendar from the calendar in use at
the time (e.g. from the Julian calendar). The date of Nero's birth
is the 15th of December 37, in the Julian Calendar, which is the
13th of December 37 in the proleptic Gregorian Calendar.</li> <!--
This might not be true. I can't find a reference that gives his
birthday with an explicit statement about the calendar being
used. However, it seems unlikely that it would be given in the
Gregorian calendar, so I assume sites use the Julian one. -->
<li>The time and time-zone offset components are not optional.</li>
<li>Dates before the year one can't be represented as a datetime
in this version of HTML.</li>
<li>Time-zone offsets differ based on daylight savings time.</li>
</ul>
</div>
<div class="impl">
<p>The <dfn>best representation of the global date and time
string</dfn> <var title="">datetime</var> is the <span>valid global
date and time string</span> representing <var
title="">datetime</var> with the last character of the string not
being a U+005A LATIN CAPITAL LETTER Z character (Z), even if the
time zone is UTC, and with a U+002D HYPHEN-MINUS character (-)
representing the sign of the time-zone offset when the time zone is
UTC.</p>
<p>The rules to <dfn>parse a global date and time string</dfn> are
as follows. This will return either a time in UTC, with associated
time-zone offset information for round tripping or display purposes,
or nothing. If at any point the algorithm says that it "fails", this
means that it is aborted at that point and returns nothing.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Parse a date component</span> to obtain <var
title="">year</var>, <var title="">month</var>, and <var
title="">day</var>. If this returns nothing, then fail.</p>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var> or if the character at <var
title="">position</var> is not a U+0054 LATIN CAPITAL LETTER T
character (T) then fail. Otherwise, move <var
title="">position</var> forwards one character.</p></li>
<li><p><span>Parse a time component</span> to obtain <var
title="">hour</var>, <var title="">minute</var>, and <var
title="">second</var>. If this returns nothing, then fail.</p>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var>, then fail.</p></li>
<li><p><span>Parse a time-zone offset component</span> to obtain
<var title="">timezone<sub title="">hours</sub></var> and <var
title="">timezone<sub title="">minutes</sub></var>. If this returns
nothing, then fail.</p>
<li><p>If <var title="">position</var> is <em>not</em> beyond the
end of <var title="">input</var>, then fail.</p></li>
<li><p>Let <var title="">time</var> be the moment in time at year
<var title="">year</var>, month <var title="">month</var>, day <var
title="">day</var>, hours <var title="">hour</var>, minute <var
title="">minute</var>, second <var title="">second</var>,
subtracting <var title="">timezone<sub title="">hours</sub></var>
hours and <var title="">timezone<sub title="">minutes</sub></var>
minutes. That moment in time is a moment in the UTC
time zone.</p></li>
<li><p>Let <var title="">timezone</var> be <var
title="">timezone<sub title="">hours</sub></var> hours and <var
title="">timezone<sub title="">minutes</sub></var> minutes from
UTC.</p></li>
<li><p>Return <var title="">time</var> and <var
title="">timezone</var>.</p></li>
</ol>
<p>The rules to <dfn>parse a time-zone offset component</dfn>, given
an <var title="">input</var> string and a <var
title="">position</var>, are as follows. This will return either
time-zone hours and time-zone minutes, or nothing. If at any point
the algorithm says that it "fails", this means that it is aborted at
that point and returns nothing.</p>
<ol>
<li>
<p>If the character at <var title="">position</var> is a U+005A
LATIN CAPITAL LETTER Z character (Z), then:</p>
<ol>
<li><p>Let <var title="">timezone<sub title="">hours</sub></var>
be 0.</p></li>
<li><p>Let <var title="">timezone<sub
title="">minutes</sub></var> be 0.</p></li>
<li><p>Advance <var title="">position</var> to the next character
in <var title="">input</var>.</p></li>
</ol>
<p>Otherwise, if the character at <var title="">position</var> is
either a U+002B PLUS SIGN (+) or a U+002D HYPHEN-MINUS (-),
then:</p>
<ol>
<li><p>If the character at <var title="">position</var> is a
U+002B PLUS SIGN (+), let <var title="">sign</var> be
"positive". Otherwise, it's a U+002D HYPHEN-MINUS (-); let <var
title="">sign</var> be "negative".</p></li>
<li><p>Advance <var title="">position</var> to the next character
in <var title="">input</var>.</p></li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not exactly two characters long, then
fail. Otherwise, interpret the resulting sequence as a base-ten
integer. Let that number be the <var title="">timezone<sub
title="">hours</sub></var>.</p></li>
<li>If <var title="">timezone<sub title="">hours</sub></var> is
not a number in the range 0 ≤ <var
title="">timezone<sub
title="">hours</sub></var> ≤ 23, then fail.</li>
<li>If <var title="">sign</var> is "negative", then negate <var
title="">timezone<sub title="">hours</sub></var>.</li>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var> or if the character at <var
title="">position</var> is not a U+003A COLON character, then
fail. Otherwise, move <var title="">position</var> forwards one
character.</p></li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not exactly two characters long, then
fail. Otherwise, interpret the resulting sequence as a base-ten
integer. Let that number be the <var title="">timezone<sub
title="">minutes</sub></var>.</p></li>
<li>If <var title="">timezone<sub title="">minutes</sub></var> is
not a number in the range 0 ≤ <var
title="">timezone<sub
title="">minutes</sub></var> ≤ 59, then fail.</li>
<li>If <var title="">sign</var> is "negative", then negate <var
title="">timezone<sub title="">minutes</sub></var>.</li>
</ol>
<p>Otherwise, fail.</p>
</li>
<li><p>Return <var title="">timezone<sub title="">hours</sub></var>
and <var title="">timezone<sub
title="">minutes</sub></var>.</p></li>
</ol>
</div>
<h5>Weeks</h5>
<p>A <dfn title="concept-week">week</dfn> consists of a week-year
number and a week number representing a seven-day period starting on
a Monday. Each week-year in this calendaring system has either 52 or
53 such seven-day periods, as defined below. The seven-day period
starting on the Gregorian date Monday December 29th 1969
(1969-12-29) is defined as week number 1 in week-year
1970. Consecutive weeks are numbered sequentially. The week before
the number 1 week in a week-year is the last week in the previous
week-year, and vice versa. <a
href="#refsGREGORIAN">[GREGORIAN]</a></p>
<p>A week-year with a number <var title="">year</var> has 53 weeks
if it corresponds to either a year <var title="">year</var> in the
proleptic Gregorian calendar that has a Thursday as its first day
(January 1st), or a year <var title="">year</var> in the proleptic
Gregorian calendar that has a Wednesday as its first day (January
1st) and where <var title="">year</var> is a number divisible by
400, or a number divisible by 4 but not by 100. All other week-years
have 52 weeks.</p>
<p>The <dfn>week number of the last day</dfn> of a week-year with 53
weeks is 53; the week number of the last day of a week-year with 52
weeks is 52.</p>
<p class="note">The week-year number of a particular day can be
different than the number of the year that contains that day in the
proleptic Gregorian calendar. The first week in a week-year <var
title="">y</var> is the week that contains the first Thursday of
the Gregorian year <var title="">y</var>.</p>
<p>A string is a <dfn>valid week string</dfn> representing a
week-year <var title="">year</var> and week <var title="">week</var>
if it consists of the following components in the given order:</p>
<ol>
<li>Four or more <span
title="concept-datetime-digit">digits</span>, representing <var
title="">year</var>, where <var
title="">year</var> > 0</li>
<li>A U+002D HYPHEN-MINUS character (-)</li>
<li>A U+0057 LATIN CAPITAL LETTER W character (W)</li>
<li>Two <span title="concept-datetime-digit">digits</span>,
representing the week <var title="">week</var>, in the range
1 ≤ <var title="">week</var> ≤ <var
title="">maxweek</var>, where <var title="">maxweek</var> is the
<span>week number of the last day</span> of week-year <var
title="">year</var></li>
</ol>
<div class="impl">
<p>The rules to <dfn>parse a week string</dfn> are as follows. This
will return either a week-year number and week number, or
nothing. If at any point the algorithm says that it "fails", this
means that it is aborted at that point and returns nothing.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not at least four characters long, then
fail. Otherwise, interpret the resulting sequence as a base-ten
integer. Let that number be the <var title="">year</var>.</p></li>
<li><p>If <var title="">year</var> is not a number greater than
zero, then fail.</p></li>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var> or if the character at <var
title="">position</var> is not a U+002D HYPHEN-MINUS character,
then fail. Otherwise, move <var title="">position</var> forwards
one character.</p></li>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var> or if the character at <var
title="">position</var> is not a U+0057 LATIN CAPITAL LETTER W
character (W), then fail. Otherwise, move <var
title="">position</var> forwards one character.</p></li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected
sequence is not exactly two characters long, then fail. Otherwise,
interpret the resulting sequence as a base-ten integer. Let that
number be the <var title="">week</var>.</p></li>
<li><p>Let <var title="">maxweek</var> be the <span>week number of
the last day</span> of year <var title="">year</var>.</p></li>
<li><p>If <var title="">week</var> is not a number in the range
1 ≤ <var title="">week</var> ≤ <var
title="">maxweek</var>, then fail.</p></li>
<li><p>If <var title="">position</var> is <em>not</em> beyond the
end of <var title="">input</var>, then fail.</p></li>
<li><p>Return the week-year number <var title="">year</var> and the
week number <var title="">week</var>.</p></li>
</ol>
</div>
<h5>Vaguer moments in time</h5>
<p>A string is a <dfn>valid date or time string</dfn> if it is also
one of the following:</p>
<ul>
<li>A <span>valid date string</span>.</li>
<li>A <span>valid time string</span>.</li>
<li>A <span>valid global date and time string</span>.</li>
</ul>
<p>A string is a <dfn>valid date or time string in content</dfn> if
it consists of zero or more <span>White_Space</span> characters,
followed by a <span>valid date or time string</span>, followed by
zero or more further <span>White_Space</span> characters.</p>
<hr>
<p>A string is a <dfn>valid date string with optional time</dfn> if
it is also one of the following:</p>
<ul>
<li>A <span>valid date string</span>.</li>
<li>A <span>valid global date and time string</span>.</li>
</ul>
<p>A string is a <dfn>valid date string in content with optional
time</dfn> if it consists of zero or more <span>White_Space</span>
characters, followed by a <span>valid date string with optional
time</span>, followed by zero or more further
<span>White_Space</span> characters.</p>
<div class="impl">
<hr>
<p>The rules to <dfn>parse a date or time string</dfn> are as
follows. The algorithm is invoked with a flag indicating if the
<i>in attribute</i> variant or the <i>in content</i> variant is to
be used. The algorithm will return either a <span
title="concept-date">date</span>, a <span
title="concept-time">time</span>, a <span
title="concept-datetime">global date and time</span>, or nothing. If
at any point the algorithm says that it "fails", this means that it
is aborted at that point and returns nothing.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>For the <i>in content</i> variant: <span>skip White_Space
characters</span>.</p></li>
<li><p>Set <var title="">start position</var> to the same position
as <var title="">position</var>.</p></li>
<li><p>Set the <var title="">date present</var> and <var
title="">time present</var> flags to true.</p></li>
<li><p><span>Parse a date component</span> to obtain <var
title="">year</var>, <var title="">month</var>, and <var
title="">day</var>. If this fails, then set the <var title="">date
present</var> flag to false.</p>
<li>
<p>If <var title="">date present</var> is true, and <var
title="">position</var> is not beyond the end of <var
title="">input</var>, and the character at <var
title="">position</var> is a U+0054 LATIN CAPITAL LETTER T
character (T), then advance <var title="">position</var> to the
next character in <var title="">input</var>.</p>
<p>Otherwise, if <var title="">date present</var> is true, and
either <var title="">position</var> is beyond the end of <var
title="">input</var> or the character at <var
title="">position</var> is not a U+0054 LATIN CAPITAL LETTER T
character (T), then set <var title="">time present</var> to
false.</p>
<p>Otherwise, if <var title="">date present</var> is false, set
<var title="">position</var> back to the same position as <var
title="">start position</var>.</p>
</li>
<li><p>If the <var title="">time present</var> flag is true, then
<span>parse a time component</span> to obtain <var
title="">hour</var>, <var title="">minute</var>, and <var
title="">second</var>. If this returns nothing, then set the <var
title="">time present</var> flag to false.</p>
<li><p>If both the <var title="">date present</var> and <var
title="">time present</var> flags are false, then fail.</p></li>
<li><p>If the <var title="">date present</var> and <var
title="">time present</var> flags are both true, but <var
title="">position</var> is beyond the end of <var
title="">input</var>, then fail.</p></li>
<li><p>If the <var title="">date present</var> and <var
title="">time present</var> flags are both true, <span>parse a
time-zone offset component</span> to obtain <var
title="">timezone<sub title="">hours</sub></var> and <var
title="">timezone<sub title="">minutes</sub></var>. If this returns
nothing, then fail.</p>
<li><p>For the <i>in content</i> variant: <span>skip White_Space
characters</span>.</p></li>
<li><p>If <var title="">position</var> is <em>not</em> beyond the
end of <var title="">input</var>, then fail.</p></li>
<li>
<p>If the <var title="">date present</var> flag is true and the
<var title="">time present</var> flag is false, then let <var
title="">date</var> be the date with year <var
title="">year</var>, month <var title="">month</var>, and day <var
title="">day</var>, and return <var title="">date</var>.</p>
<p>Otherwise, if the <var title="">time present</var> flag is true
and the <var title="">date present</var> flag is false, then let
<var title="">time</var> be the time with hour <var
title="">hour</var>, minute <var title="">minute</var>, and second
<var title="">second</var>, and return <var
title="">time</var>.</p>
<p>Otherwise, let <var title="">time</var> be the moment in time
at year <var title="">year</var>, month <var title="">month</var>,
day <var title="">day</var>, hours <var title="">hour</var>,
minute <var title="">minute</var>, second <var
title="">second</var>, subtracting <var title="">timezone<sub
title="">hours</sub></var> hours and <var title="">timezone<sub
title="">minutes</sub></var> minutes, that moment in time being a
moment in the UTC time zone; let <var title="">timezone</var> be
<var title="">timezone<sub title="">hours</sub></var> hours and
<var title="">timezone<sub title="">minutes</sub></var> minutes
from UTC; and return <var title="">time</var> and <var
title="">timezone</var>.</p>
</li>
</ol>
</div>
<h4>Colors</h4>
<p>A <dfn>simple color</dfn> consists of three 8-bit numbers in the
range 0..255, representing the red, green, and blue components of
the color respectively, in the sRGB color space. <a
href="#refsSRGB">[SRGB]</a></p>
<p>A string is a <dfn>valid simple color</dfn> if it is exactly
seven characters long, and the first character is a U+0023 NUMBER
SIGN character (#), and the remaining six characters are all in the
range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN
CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, U+0061 LATIN
SMALL LETTER A to U+0066 LATIN SMALL LETTER F, with the first two
digits representing the red component, the middle two digits
representing the green component, and the last two digits
representing the blue component, in hexadecimal.</p>
<p>A string is a <dfn>valid lowercase simple color</dfn> if it is a
<span>valid simple color</span> and doesn't use any characters in
the range U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL
LETTER F.</p>
<div class="impl">
<p>The <dfn>rules for parsing simple color values</dfn> are as given
in the following algorithm. When invoked, the steps must be followed
in the order given, aborting at the first step that returns a
value. This algorithm will return either a <span>simple color</span>
or an error.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>If <var title="">input</var> is not exactly seven characters
long, then return an error.</p></li>
<li><p>If the first character in <var title="">input</var> is not a
U+0023 NUMBER SIGN character (#), then return an error.</p></li>
<li><p>If the last six characters of <var title="">input</var> are
not all in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE
(9), U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER
F, U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, then
return an error.</p></li>
<li><p>Let <var title="">result</var> be a <span>simple
color</span>.</p>
<li><p>Interpret the second and third characters as a hexadecimal
number and let the result be the red component of <var
title="">result</var>.</p>
<li><p>Interpret the fourth and fifth characters as a hexadecimal
number and let the result be the green component of <var
title="">result</var>.</p>
<li><p>Interpret the sixth and seventh characters as a hexadecimal
number and let the result be the blue component of <var
title="">result</var>.</p>
<li><p>Return <var title="">result</var>.</p>
</ol>
<p>The <dfn>rules for serializing simple color values</dfn> given a
<span>simple color</span> are as given in the following
algorithm:</p>
<ol>
<li><p>Let <var title="">result</var> be a string consisting of a
single U+0023 NUMBER SIGN character (#).</p></li>
<li><p>Convert the red, green, and blue components in turn to
two-digit hexadecimal numbers using the digits U+0030 DIGIT ZERO
(0) to U+0039 DIGIT NINE (9) and U+0061 LATIN SMALL LETTER A
to U+0066 LATIN SMALL LETTER F, zero-padding if necessary, and
append these numbers to <var title="">result</var>, in the order
red, green, blue.</p>
<li><p>Return <var title="">result</var>, which will be a
<span>valid lowercase simple color</span>.</p></li>
</ol>
<hr>
<p>Some obsolete legacy attributes parse colors in a more
complicated manner, using the <dfn>rules for parsing a legacy color
value</dfn>, which are given in the following algorithm. When
invoked, the steps must be followed in the order given, aborting at
the first step that returns a value. This algorithm will return
either a <span>simple color</span> or an error.</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>If <var title="">input</var> is the empty string, then
return an error.</p></li>
<li><p>If <var title="">input</var> is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">transparent</code>", then return an error.</p></li>
<li><p>If <var title="">input</var> is an <span>ASCII
case-insensitive</span> match for one of the keywords listed in the
<a href="http://www.w3.org/TR/css3-color/#svg-color">SVG color
keywords</a> or <a
href="http://www.w3.org/TR/css3-color/#css2-system">CSS2 System
Colors</a> sections of the CSS3 Color specification, then return
the <span>simple color</span> corresponding to that keyword. <a
href="#refsCSSCOLOR">[CSSCOLOR]</a></p></li>
<li>
<p>If <var title="">input</var> is four characters long, and the
first character in <var title="">input</var> is a U+0023 NUMBER
SIGN character (#), and the last three characters of <var
title="">input</var> are all in the range U+0030 DIGIT ZERO (0)
to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+0046
LATIN CAPITAL LETTER F, and U+0061 LATIN SMALL LETTER A to U+0066
LATIN SMALL LETTER F, then run these substeps:</p>
<ol>
<li><p>Let <var title="">result</var> be a <span>simple
color</span>.</p>
<li><p>Interpret the second character of <var
title="">input</var> as a hexadecimal digit; let the red
component of <var title="">result</var> be the resulting number
multiplied by 17.</p>
<li><p>Interpret the third character of <var title="">input</var>
as a hexadecimal digit; let the green component of <var
title="">result</var> be the resulting number multiplied by
17.</p>
<li><p>Interpret the fourth character of <var
title="">input</var> as a hexadecimal digit; let the blue
component of <var title="">result</var> be the resulting number
multiplied by 17.</p>
<li><p>Return <var title="">result</var>.</p>
</ol>
</li>
<li><p>Replace any characters in <var title="">input</var> that
have a Unicode code point greater than U+FFFF (i.e. any characters
that are not in the basic multilingual plane) with the
two-character string "<code title="">00</code>".</p></li>
<li><p>If <var title="">input</var> is longer than 128 characters,
truncate <var title="">input</var>, leaving only the first 128
characters.</p></li>
<li><p>If the first character in <var title="">input</var> is a
U+0023 NUMBER SIGN character (#), remove it.</p></li>
<li><p>Replace any character in <var title="">input</var> that is
not in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9),
U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, and
U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F with the
character U+0030 DIGIT ZERO (0).</p></li>
<li><p>While <var title="">input</var>'s length is zero or not a
multiple of three, append a U+0030 DIGIT ZERO (0) character to <var
title="">input</var>.</p></li>
<li><p>Split <var title="">input</var> into three strings of equal
length, to obtain three components. Let <var title="">length</var>
be the length of those components (one third the length of <var
title="">input</var>).</p></li>
<li><p>If <var title="">length</var> is greater than 8, then remove
the leading <span title=""><var title="">length</var>-8</span>
characters in each component, and let <var title="">length</var> be
8.</p></li>
<li><p>While <var title="">length</var> is greater than two and the
first character in each component is a U+0030 DIGIT ZERO (0)
character, remove that character and reduce <var
title="">length</var> by one.</p></li>
<li><p>If <var title="">length</var> is <em>still</em> greater than
two, truncate each component, leaving only the first two
characters in each.</p></li>
<li><p>Let <var title="">result</var> be a <span>simple
color</span>.</p>
<li><p>Interpret the first component as a hexadecimal number; let
the red component of <var title="">result</var> be the resulting
number.</p></li>
<li><p>Interpret the second component as a hexadecimal number; let
the green component of <var title="">result</var> be the resulting
number.</p></li>
<li><p>Interpret the third component as a hexadecimal number; let
the blue component of <var title="">result</var> be the resulting
number.</p></li>
<li><p>Return <var title="">result</var>.</p>
</ol>
</div>
<hr>
<p class="note">The <span title="canvas-context-2d">2D graphics
context</span> has a separate color syntax that also handles
opacity.</p>
<h4>Space-separated tokens</h4>
<p>A <dfn>set of space-separated tokens</dfn> is a string containing
zero or more words separated by one or more <span title="space
character">space characters</span>, where words consist of any
string of one or more characters, none of which are <span
title="space character">space characters</span>.</p>
<p>A string containing a <span>set of space-separated tokens</span>
may have leading or trailing <span title="space character">space
characters</span>.</p>
<p>An <dfn>unordered set of unique space-separated tokens</dfn> is a
<span>set of space-separated tokens</span> where none of the words
are duplicated.</p>
<p>An <dfn>ordered set of unique space-separated tokens</dfn> is a
<span>set of space-separated tokens</span> where none of the words
are duplicated but where the order of the tokens is meaningful.</p>
<p><span title="set of space-separated tokens">Sets of
space-separated tokens</span> sometimes have a defined set of
allowed values. When a set of allowed values is defined, the tokens
must all be from that list of allowed values; other values are
non-conforming. If no such set of allowed values is provided, then
all values are conforming.</p>
<div class="impl">
<p>When a user agent has to <dfn>split a string on spaces</dfn>, it
must use the following algorithm:</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>Let <var title="">tokens</var> be a list of tokens,
initially empty.</p></li>
<li><p><span>Skip whitespace</span></p></li>
<li><p>While <var title="">position</var> is not past the end of
<var title="">input</var>:</p>
<ol>
<li><p><span>Collect a sequence of characters</span> that are not
<span title="space character">space characters</span>.</p></li>
<li><p>Add the string collected in the previous step to <var
title="">tokens</var>.</p></li>
<li><p><span>Skip whitespace</span></p></li>
</ol>
</li>
<li><p>Return <var title="">tokens</var>.</p></li>
</ol>
<p>When a user agent has to <dfn>remove a token from a string</dfn>,
it must use the following algorithm:</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
modified.</p></li>
<li><p>Let <var title="">token</var> be the token being removed. It
will not contain any <span title="space character">space
characters</span>.</p></li>
<li><p>Let <var title="">output</var> be the output string,
initially empty.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>If <var title="">position</var> is beyond the end of <var
title="">input</var>, set the string being modified to <var
title="">output</var>, and abort these steps.</p></li>
<li><p>If the character at <var title="">position</var> is a
<span>space character</span>:</p>
<ol>
<li><p>Append the character at <var title="">position</var> to
the end of <var title="">output</var>.</p></li>
<li><p>Advance <var title="">position</var> so it points at the
next character in <var title="">input</var>.</p></li>
<li><p>Return to step 5 in the overall set of steps.</p></li>
</ol>
</li>
<li><p>Otherwise, the character at <var title="">position</var> is
the first character of a token. <span>Collect a sequence of
characters</span> that are not <span title="space character">space
characters</span>, and let that be <var title="">s</var>.</p></li>
<li><p>If <var title="">s</var> is exactly equal to <var
title="">token</var>, then:</p>
<ol>
<li><p><span>Skip whitespace</span> (in <var
title="">input</var>).</p></li>
<li><p>Remove any <span title="space character">space
characters</span> currently at the end of <var
title="">output</var>.</p></li>
<li><p>If <var title="">position</var> is not past the end of
<var title="">input</var>, and <var title="">output</var> is not
the empty string, append a single U+0020 SPACE character at the
end of <var title="">output</var>.</p></li>
</ol>
</li>
<li><p>Otherwise, append <var title="">s</var> to the end of <var
title="">output</var>.</p></li>
<li><p>Return to step 6 in the overall set of steps.</p></li>
</ol>
<p class="note">This causes any occurrences of the token to be
removed from the string, and any spaces that were surrounding the
token to be collapsed to a single space, except at the start and end
of the string, where such spaces are removed.</p>
</div>
<h4>Comma-separated tokens</h4>
<p>A <dfn>set of comma-separated tokens</dfn> is a string containing
zero or more tokens each separated from the next by a single U+002C
COMMA character (,), where tokens consist of any string of zero or
more characters, neither beginning nor ending with <span
title="space character">space characters</span>, nor containing any
U+002C COMMA characters (,), and optionally surrounded by <span
title="space character">space characters</span>.</p>
<p class="example">For instance, the string "<code
title=""> a ,b,,d d </code>" consists of four
tokens: "a", "b", the empty string, and "d d". Leading and
trailing whitespace around each token doesn't count as part of the
token, and the empty string can be a token.</p>
<p><span title="set of comma-separated tokens">Sets of
comma-separated tokens</span> sometimes have further restrictions on
what consists a valid token. When such restrictions are defined, the
tokens must all fit within those restrictions; other values are
non-conforming. If no such restrictions are specified, then all
values are conforming.</p>
<div class="impl">
<p>When a user agent has to <dfn>split a string on commas</dfn>, it
must use the following algorithm:</p>
<ol>
<li><p>Let <var title="">input</var> be the string being
parsed.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p>Let <var title="">tokens</var> be a list of tokens,
initially empty.</p></li>
<li><p><i>Token</i>: If <var title="">position</var> is past the
end of <var title="">input</var>, jump to the last step.</p></li>
<li><p><span>Collect a sequence of characters</span> that are not
U+002C COMMA characters (,). Let <var
title="">s</var> be the resulting sequence (which might be the
empty string).</p></li>
<li><p>Remove any leading or trailing sequence of <span
title="space character">space characters</span> from <var
title="">s</var>.</p></li>
<li><p>Add <var title="">s</var> to <var
title="">tokens</var>.</p></li>
<li><p>If <var title="">position</var> is not past the end of <var
title="">input</var>, then the character at <var
title="">position</var> is a U+002C COMMA character (,); advance
<var title="">position</var> past that character.</p></li>
<li><p>Jump back to the step labeled <i>token</i>.</p></li>
<li><p>Return <var title="">tokens</var>.</p></li>
</ol>
</div>
<h4 id="syntax-references">References</h4>
<p>A <dfn>valid hash-name reference</dfn> to an element of type <var
title="">type</var> is a string consisting of a U+0023 NUMBER SIGN
character (#) followed by a string which exactly matches the value
of the <code title="">name</code> attribute of an element in the
document with type <var title="">type</var>.</p>
<div class="impl">
<p>The <dfn>rules for parsing a hash-name reference</dfn> to an
element of type <var title="">type</var> are as follows:</p>
<ol>
<li><p>If the string being parsed does not contain a U+0023 NUMBER
SIGN character, or if the first such character in the string is the
last character in the string, then return null and abort these
steps.</p></li>
<li><p>Let <var title="">s</var> be the string from the character
immediately after the first U+0023 NUMBER SIGN character in the
string being parsed up to the end of that string.</p></li>
<li><p>Return the first element of type <var title="">type</var>
that has an <code title="attr-id">id</code> attribute whose value
is a <span>case-sensitive</span> match for <var title="">s</var> or
a <code title="">name</code> attribute whose value is a
<span>compatibility caseless</span> match for <var
title="">s</var>.</p></li>
<!--
IE is also doing case-insensitive id="" matching.
Tests:
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A%3Cmap%20name%3D%22T%26eacute%3B%26%23x01F1%3B%26%23x2075%3B%22%3E%3Carea%20href%3D%22%2F%22%20shape%3Drect%20coords%3D0%2C0%2C200%2C200%3E%3C%2Fmap%3E%0A%3Cimg%20usemap%3D%22%23t%26Eacute%3BDZ5%22%20src%3Dimage%3E
...except that doesn't explain why this fails:
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A%3Cmap%20name%3D%22T%26eacute%3B%26%23x01F1%3B%26%23x2075%3B%26%23xFB01%3B%22%3E%3Carea%20href%3D%22%2F%22%20shape%3Drect%20coords%3D0%2C0%2C200%2C200%3E%3C%2Fmap%3E%0A%3Cimg%20usemap%3D%22%23t%26Eacute%3BDZ5F%26%23x0131%3B%26%23x0307%3B%22%20src%3Dimage%3E
maybe they just don't know about combining dot above?
-->
</ol>
</div>
<h4 id="mq">Media queries</h4>
<p>A string is a <dfn>valid media query</dfn> if it matches the
<code title="">media_query_list</code> production of the Media
Queries specification. <a href="#refsMQ">[MQ]</a></p>
<p>A string <dfn>matches the environment</dfn> of a view if it is
the empty string, a string consisting of only <span title="space
character">space characters</span>, or is a media query that matches
that view's environment according to the definitions given in the
Media Queries specification. <a href="#refsMQ">[MQ]</a></p>
<h3>URLs</h3>
<h4>Terminology</h4>
<p>A <dfn>URL</dfn> is a string used to identify a resource.</p>
<p>A <span>URL</span> is a <dfn>valid URL</dfn> if it is a
<span>valid Web address</span> as defined by the Web addresses
specification. <a href="#refsWEBADDRESSES">[WEBADDRESSES]</a></p>
<p>A <span>URL</span> is an <dfn>absolute URL</dfn> if it is an
<span>absolute Web address</span> as defined by the Web addresses
specification. <a href="#refsWEBADDRESSES">[WEBADDRESSES]</a></p>
<div class="impl">
<p>To <dfn>parse a URL</dfn> <var title="">url</var> into its
component parts, the user agent must use the <span>parse a Web
address</span> algorithm defined by the Web addresses
specification. <a href="#refsWEBADDRESSES">[WEBADDRESSES]</a></p>
<p>Parsing a URL results in the following components, again as
defined by the Web addresses specification:</p>
<ul class="brief">
<li><dfn title="url-scheme"><scheme></dfn></li>
<li><dfn title="url-host"><host></dfn></li>
<li><dfn title="url-port"><port></dfn></li>
<li><dfn title="url-hostport"><hostport></dfn></li>
<li><dfn title="url-path"><path></dfn></li>
<li><dfn title="url-query"><query></dfn></li>
<li><dfn title="url-fragment"><fragment></dfn></li>
<li><dfn title="url-host-specific"><host-specific></dfn></li>
</ul>
<p>To <dfn>resolve a URL</dfn> to an <span>absolute URL</span>
relative to either another <span>absolute URL</span> or an element,
the user agent must use the <span>resolve a Web address</span>
algorithm defined by the Web addresses specification. <a
href="#refsWEBADDRESSES">[WEBADDRESSES]</a></p>
<p>The <dfn>document base URL</dfn> of a <code>Document</code>
object is the <span>absolute URL</span> obtained by running these
substeps:</p>
<ol>
<li><p>Let <var title="">fallback base url</var> be <span>the
document's address</span>.</p></li>
<li>
<!-- http://www.hixie.ch/tests/adhoc/html/navigation/javascript-url/ -->
<!-- this should be tested in the case of a browsing context that
was navigated to about:blank after having been elsewhere, as
opposed to the about:blank used at the time of the browsing
context's creation. -->
<p>If <var title="">fallback base url</var> is
<code>about:blank</code>, and the <code>Document</code>'s
<span>browsing context</span> has a <span>creator browsing
context</span>, then let <var title="">fallback base url</var>
be the <span>document base URL</span> of the <span>creator
<code>Document</code></span> instead.</p>
</li>
<li><p>If there is no <code>base</code> element that is both a
child of <span>the <code>head</code> element</span> and has an
<code title="attr-base-href">href</code> attribute, then the
<span>document base URL</span> is <var title="">fallback base
url</var>.</p></li>
<li><p>Otherwise, let <var title="">url</var> be the value of the
<code title="attr-base-href">href</code> attribute of the first
such element.</p></li>
<li><p><span title="resolve a URL">Resolve</span> <var
title="">url</var> relative to <var title="">fallback base
url</var> (thus, the <code>base</code> <code
title="attr-base-href">href</code> attribute isn't affected by
<code title="attr-xml-base">xml:base</code> attributes).</p></li>
<li><p>The <span>document base URL</span> is the result of the
previous step if it was successful; otherwise it is <var
title="">fallback base url</var>.</p></li>
</ol>
<p>This specification defines the URL
<dfn><code>about:legacy-compat</code></dfn> as a reserved, though
unresolvable, <code title="">about:</code> URI. <a
href="#refsABOUT">[ABOUT]</a></p>
</div>
<p class="note">The term "URL" in this specification is used in a
manner distinct from the precise technical meaning it is given in
RFC 3986. Readers familiar with that RFC will find it easier to read
<em>this</em> specification if they pretend the term "URL" as used
herein is really called something else altogether. This is a
<span>willful violation</span> of RFC 3986. <a
href="#refsRFC3986">[RFC3986]</a></p>
<div class="impl">
<h4>Dynamic changes to base URLs</h4>
<p>When an <code title="attr-xml-base">xml:base</code> attribute
changes, the attribute's element, and all descendant elements, are
<span>affected by a base URL change</span>.</p>
<p>When a document's <span>document base URL</span> changes, all
elements in that document are <span>affected by a base URL
change</span>.</p>
<p>When an element is moved from one document to another, if the two
documents have different <span title="document base URL">base
URLs</span>, then that element and all its descendants are
<span>affected by a base URL change</span>.</p>
<p>When an element is <dfn>affected by a base URL change</dfn>, it
must act as described in the following list:</p>
<dl class="switch">
<dt>If the element is a <span title="hyperlink">hyperlink
element</span></dt>
<dd>
<p>If the <span>absolute URL</span> identified by the hyperlink is
being shown to the user, or if any data derived from that URL is
affecting the display, then the <code
title="attr-hyperlink-href">href</code> attribute should be <span
title="resolve a url">re-resolved</span> relative to the element
and the UI updated appropriately.</p>
<p class="example">For example, the CSS <code
title="selector-link">:link</code>/<code
title="selector-visited">:visited</code> pseudo-classes might have
been affected.</p>
<p>If the hyperlink has a <code
title="attr-hyperlink-ping">ping</code> attribute and its <span
title="absolute URL">absolute URL(s)</span> are being shown to the
user, then the <code title="attr-hyperlink-ping">ping</code>
attribute's tokens should be <span title="resolve a
url">re-resolved</span> relative to the element and the UI updated
appropriately.</p>
</dd>
<dt>If the element is a <code>q</code>, <code>blockquote</code>,
<code>section</code>, <code>article</code>, <code>ins</code>, or
<code>del</code> element with a <code title="">cite</code>
attribute</dt>
<dd>
<p>If the <span>absolute URL</span> identified by the <code
title="">cite</code> attribute is being shown to the user, or if
any data derived from that URL is affecting the display, then the
<span>URL</span> should be <span title="resolve a
url">re-resolved</span> relative to the element and the UI updated
appropriately.</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p>The element is not directly affected.</p>
<p class="example">Changing the base URL doesn't affect the image
displayed by <code>img</code> elements, although subsequent
accesses of the <code title="dom-img-src">src</code> IDL attribute
from script will return a new <span>absolute URL</span> that might
no longer correspond to the image being shown.</p>
</dd>
</dl>
</div>
<h4>Interfaces for URL manipulation</h4>
<p>An interface that has a complement of <dfn>URL decomposition IDL
attributes</dfn> will have seven attributes with the following
definitions:</p>
<pre class="idl extract"> attribute DOMString <span title="dom-uda-protocol">protocol</span>;
attribute DOMString <span title="dom-uda-host">host</span>;
attribute DOMString <span title="dom-uda-hostname">hostname</span>;
attribute DOMString <span title="dom-uda-port">port</span>;
attribute DOMString <span title="dom-uda-pathname">pathname</span>;
attribute DOMString <span title="dom-uda-search">search</span>;
attribute DOMString <span title="dom-uda-hash">hash</span>;</pre>
<dl class="domintro">
<dt><var title="">o</var> . <code title="dom-uda-protocol">protocol</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current scheme of the underlying URL.</p>
<p>Can be set, to change the underlying URL's scheme.</p>
</dd>
<dt><var title="">o</var> . <code title="dom-uda-host">host</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current host and port (if it's not the default port) in the underlying URL.</p>
<p>Can be set, to change the underlying URL's host and port.</p>
<p>The host and the port are separated by a colon. The port part,
if omitted, will be assumed to be the current scheme's default
port.</p>
</dd>
<dt><var title="">o</var> . <code title="dom-uda-hostname">hostname</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current host in the underlying URL.</p>
<p>Can be set, to change the underlying URL's host.</p>
</dd>
<dt><var title="">o</var> . <code title="dom-uda-port">port</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current port in the underlying URL.</p>
<p>Can be set, to change the underlying URL's port.</p>
</dd>
<dt><var title="">o</var> . <code title="dom-uda-pathname">pathname</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current path in the underlying URL.</p>
<p>Can be set, to change the underlying URL's path.</p>
</dd>
<dt><var title="">o</var> . <code title="dom-uda-search">search</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current query component in the underlying URL.</p>
<p>Can be set, to change the underlying URL's query component.</p>
</dd>
<dt><var title="">o</var> . <code title="dom-uda-hash">hash</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current fragment identifier in the underlying URL.</p>
<p>Can be set, to change the underlying URL's fragment identifier.</p>
</dd>
</dl>
<div class="impl">
<hr>
<p>The attributes defined to be URL decomposition IDL attributes must
act as described for the attributes with the same corresponding
names in this section.</p>
<p>In addition, an interface with a complement of URL decomposition IDL
attributes will define an <dfn
title="concept-uda-input">input</dfn>, which is a <span>URL</span>
that the attributes act on, and a <dfn
title="concept-uda-setter">common setter action</dfn>, which is a
set of steps invoked when any of the attributes' setters are
invoked.</p>
<p>The seven URL decomposition IDL attributes have similar
requirements.</p>
<p>On getting, if the <span title="concept-uda-input">input</span>
is an <span>absolute URL</span> that fulfills the condition given in
the "getter condition" column corresponding to the attribute in the
table below, the user agent must return the part of the <span
title="concept-uda-input">input</span> URL given in the "component"
column, with any prefixes specified in the "prefix" column
appropriately added to the start of the string and any suffixes
specified in the "suffix" column appropriately added to the end of
the string. Otherwise, the attribute must return the empty
string.</p>
<p>On setting, the new value must first be mutated as described by
the "setter preprocessor" column, then mutated by %-escaping any
characters in the new value that are not valid in the relevant
component as given by the "component" column. Then, if the <span
title="concept-uda-input">input</span> is an <span>absolute
URL</span> and the resulting new value fulfills the condition given
in the "setter condition" column, the user agent must make a new
string <var title="">output</var> by replacing the component of the
URL given by the "component" column in the <span
title="concept-uda-input">input</span> URL with the new value;
otherwise, the user agent must let <var title="">output</var> be
equal to the <span title="concept-uda-input">input</span>. Finally,
the user agent must invoke the <span
title="concept-uda-setter">common setter action</span> with the
value of <var title="">output</var>.</p>
<p>When replacing a component in the URL, if the component is part
of an optional group in the URL syntax consisting of a character
followed by the component, the component (including its prefix
character) must be included even if the new value is the empty
string.</p>
<p class="note">The previous paragraph applies in particular to the
"<code title="">:</code>" before a <port> component, the "<code
title="">?</code>" before a <query> component, and the "<code
title="">#</code>" before a <fragment> component.</p>
<p>For the purposes of the above definitions, URLs must be parsed
using the <span title="parse a URL">URL parsing rules</span> defined
in this specification.</p>
<table>
<thead>
<tr>
<th>Attribute
<th>Component
<th>Getter Condition
<th>Prefix
<th>Suffix
<th>Setter Preprocessor
<th>Setter Condition
<tbody>
<tr>
<td><dfn title="dom-uda-protocol"><code>protocol</code></dfn>
<td><span title="url-scheme"><scheme></span>
<td>—
<td>—
<td>U+003A COLON (:)
<td>Remove all trailing U+003A COLON characters (:)
<td>The new value is not the empty string
<tr>
<td><dfn title="dom-uda-host"><code>host</code></dfn>
<td><span title="url-hostport"><hostport></span>
<td><span title="concept-uda-input">input</span> is hierarchical and uses a server-based naming authority
<td>—
<td>—
<td>—
<td>The new value is not the empty string and <span title="concept-uda-input">input</span> is hierarchical and uses a server-based naming authority
<tr>
<td><dfn title="dom-uda-hostname"><code>hostname</code></dfn>
<td><span title="url-host"><host></span>
<td><span title="concept-uda-input">input</span> is hierarchical and uses a server-based naming authority
<td>—
<td>—
<td>Remove all leading U+002F SOLIDUS characters (/)
<td>The new value is not the empty string and <span title="concept-uda-input">input</span> is hierarchical and uses a server-based naming authority
<tr>
<td><dfn title="dom-uda-port"><code>port</code></dfn>
<td><span title="url-port"><port></span>
<td><span title="concept-uda-input">input</span> is hierarchical, uses a server-based naming authority, and contained a <span title="url-port"><port></span> component (possibly an empty one)
<td>—
<td>—
<td>Remove any characters in the new value that are not in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).
If the resulting string is empty, set it to a single U+0030 DIGIT ZERO character (0).
<td><span title="concept-uda-input">input</span> is hierarchical and uses a server-based naming authority
<tr>
<td><dfn title="dom-uda-pathname"><code>pathname</code></dfn>
<td><span title="url-path"><path></span>
<td><span title="concept-uda-input">input</span> is hierarchical
<td>—
<td>—
<td>If it has no leading U+002F SOLIDUS character (/), prepend a U+002F SOLIDUS character (/) to the new value
<td><span title="concept-uda-input">input</span> is hierarchical
<tr>
<td><dfn title="dom-uda-search"><code>search</code></dfn>
<td><span title="url-query"><query></span>
<td><span title="concept-uda-input">input</span> is hierarchical, and contained a <span title="url-query"><query></span> component (possibly an empty one)
<td>U+003F QUESTION MARK (?)
<td>—
<td>Remove one leading U+003F QUESTION MARK character (?), if any
<td><span title="concept-uda-input">input</span> is hierarchical
<tr>
<td><dfn title="dom-uda-hash"><code>hash</code></dfn>
<td><span title="url-fragment"><fragment></span>
<td><span title="concept-uda-input">input</span> contained a <span title="url-fragment"><fragment></span> component (possibly an empty one)
<td>U+0023 NUMBER SIGN (#)
<td>—
<td>Remove one leading U+0023 NUMBER SIGN character (#), if any
<td>—
</table>
<!--
http://www.hixie.ch/tests/adhoc/dom/level0/location/components/
http://lxr.mozilla.org/seamonkey/source/dom/src/base/nsLocation.cpp
http://wp.netscape.com/eng/mozilla/3.0/handbook/javascript/ref_h-l.htm#84722
-->
</div>
<div class="example">
<p>The table below demonstrates how the getter <span
class="impl">condition</span> for <code
title="dom-uda-search">search</code> results in different results
depending on the exact original syntax of the URL:</p>
<table>
<thead>
<tr>
<th> Input URL
<th> <code title="dom-uda-search">search</code> value
<th> Explanation
<tbody>
<tr>
<td> <code title="">http://example.com/</code>
<td> <i>empty string</i>
<td> No <span title="url-query"><query></span> component in input URL.
<tr>
<td> <code title="">http://example.com/?</code>
<td> <code title="">?</code>
<td> There is a <span title="url-query"><query></span> component, but it is empty.
<span class="impl">The question mark in the resulting value is the prefix.</span>
<tr>
<td> <code title="">http://example.com/?test</code>
<td> <code title="">?test</code>
<td> The <span title="url-query"><query></span> component has the value "<code title="">test</code>".
<tr>
<td> <code title="">http://example.com/?test#</code>
<td> <code title="">?test</code>
<td> The (empty) <span title="url-fragment"><fragment></span> component is not part of the <span title="url-query"><query></span> component.
</table>
</div>
<div class="impl">
<h3>Fetching resources</h3>
<p>When a user agent is to <dfn>fetch</dfn> a resource, optionally
from an origin <i title="">origin</i>, the following steps must be
run:</p>
<ol>
<li><p>If the resource is identified by the <span>URL</span>
<dfn><code>about:blank</code></dfn>, then return the empty string
and abort these steps.</p></li>
<li>
<p>Generate the <i>address of the resource from which Request-URIs
are obtained</i> as required by HTTP for the <code
title="http-referer">Referer</code> (sic) header from <span>the
document's current address</span> of the appropriate
<code>Document</code> as given by the following list. <a
href="#refsHTTP">[HTTP]</a></p>
<dl class="switch">
<dt>When <span title="navigate">navigating</span></dt>
<dd>The <span>active document</span> of the <span>source browsing
context</span>.</dd>
<dt>When fetching resources for an element</dt>
<dd>The element's <code>Document</code>.</dd>
<dt>When fetching resources in response to a call to an API</dt>
<dd>The <span>active document</span> of the <span title="script's
browsing context">browsing context</span> of the <span>first
script</span>.</dd>
</dl>
<p>Remove any <span title="url-fragment"><fragment></span>
component from the generated <i>address of the resource from which
Request-URIs are obtained</i>.</p> <!-- RFC2616 says "The URI MUST
NOT include a fragment." (section 14.36) -->
</li>
<li><p>Perform the remaining steps asynchronously.</p></li>
<li>
<p>If the resource is identified by an <span>absolute URL</span>,
and the resource is to be obtained using an idempotent action
(such as an HTTP GET <span title="concept-http-equivalent-get">or
equivalent</span>), and it is already being downloaded for other
reasons (e.g. another invocation of this algorithm), and this
request would be identical to the previous one (e.g. same <code
title="http-accept">Accept</code> and <code
title="http-origin">Origin</code> headers), and the user agent is
configured such that it is to reuse the data from the existing
download instead of initiating a new one, then use the results of
the existing download instead of starting a new one.</p>
<p>Otherwise, at a time convenient to the user and the user agent,
download (or otherwise obtain) the resource, applying the
semantics of the relevant specifications (e.g. performing an HTTP
GET or POST operation, or reading the file from disk, following
redirects, <span title="concept-js-deref">dereferencing <span
title="javascript protocol"><code title="">javascript:</code>
URLs</span></span>, etc).</p>
<p>For the purposes of the <code
title="http-referer">Referer</code> (sic) header, use the
<i>address of the resource from which Request-URIs are
obtained</i> generated in the earlier step.</p>
<p>For the purposes of the <code title="http-origin">Origin</code>
header, if the <span title="fetch">fetching algorithm</span> was
explicitly initiated from an <i title="">origin</i>, then <i
title="">the origin that initiated the HTTP request</i> is <i
title="">origin</i>. Otherwise, this is <i title="">a request from
a "privacy-sensitive" context</i>. <a
href="#refsORIGIN">[ORIGIN]</a></p>
</li>
<li>
<p>If there are cookies to be set, then the user agent must run
the following substeps:</p>
<ol>
<li><p>Wait until ownership of the <span>storage mutex</span> can
be taken by this instance of the <span
title="fetch">fetching</span> algorithm.</p></li>
<li><p>Take ownership of the <span>storage mutex</span>.</p></li>
<li><p>Update the cookies. <a
href="#refsCOOKIES">[COOKIES]</a></p></li>
<li><p>Release the <span>storage mutex</span> so that it is once
again free.</p></li>
</ol>
</li>
<li><p>When the resource is available, or if there is an error of
some description, <span>queue a task</span> that uses the resource
as appropriate. If the resource can be processed incrementally, as,
for instance, with a progressively interlaced JPEG or an HTML file,
additional tasks may be queued to process the data as it is
downloaded. The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <span>networking task
source</span>.</p>
</ol>
<p>If the user agent can determine the actual length of the resource
being <span title="fetch">fetched</span> for an instance of this
algorithm, and if that length is finite, then that length is the
file's <dfn title="concept-fetch-total">size</dfn>. Otherwise, the
subject of the algorithm (that is, the resource being fetched) has
no known <span title="concept-fetch-total">size</span>. (For
example, the HTTP <code
title="http-content-length">Content-Length</code> header might
provide this information.)</p>
<p>The user agent must also keep track of the <dfn
title="concept-fetch-loaded">number of bytes downloaded</dfn> for
each instance of this algorithm. This number must exclude any
out-of-band metadata, such as HTTP headers.</p>
<p class="note">The <span>application cache</span> processing model
introduces some <a href="#changesToNetworkingModel">changes to the
networking model</a> to handle the returning of cached
resources.</p>
<p class="note">The <span title="navigate">navigation</span>
processing model handles redirects itself, overriding the
redirection handling that would be done by the fetching
algorithm.</p>
<p class="note">Whether the <a href="#content-type-sniffing">type
sniffing rules</a> apply to the fetched resource depends on the
algorithm that invokes the rules — they are not always
applicable.</p>
<h4 id="concept-http-equivalent">Protocol concepts</h4>
<p>User agents can implement a variety of transfer protocols, but
this specification mostly defines behavior in terms of HTTP. <a
href="#refsHTTP">[HTTP]</a></p>
<p>The <dfn title="concept-http-equivalent-get">HTTP GET
method</dfn> is equivalent to the default retrieval action of the
protocol. For example, RETR in FTP. Such actions are idempotent and
safe, in HTTP terms.</p>
<p>The <dfn title="concept-http-equivalent-codes">HTTP response
codes</dfn> are equivalent to statuses in other protocols that have
the same basic meanings. For example, a "file not found" error is
equivalent to a 404 code, a server error is equivalent to a 5xx
code, and so on.</p>
<p>The <dfn title="concept-http-equivalent-headers">HTTP
headers</dfn> are equivalent to fields in other protocols that have
the same basic meaning. For example, the HTTP authentication
headers are equivalent to the authentication aspects of the FTP
protocol.</p>
<h4>Encrypted HTTP and related security concerns</h4>
<p>Anything in this specification that refers to HTTP also applies
to HTTP-over-TLS, as represented by <span title="url">URLs</span>
representing the <code title="">https</code> scheme.</p>
<p class="warning">User agents should report certificate errors to
the user and must either refuse to download resources sent with
erroneous certificates or must act as if such resources were in fact
served with no encryption.</p>
<p>User agents should warn the user that there is a potential
problem whenever the user visits a page that the user has previously
visited, if the page uses less secure encryption on the second
visit.</p>
<p>Not doing so can result in users not noticing man-in-the-middle
attacks.</p>
<div class="example">
<p>If a user connects to a server with a self-signed certificate,
the user agent could allow the connection but just act as if there
had been no encryption. If the user agent instead allowed the user
to override the problem and then displayed the page as if it was
fully and safely encrypted, the user could be easily tricked into
accepting man-in-the-middle connections.</p>
<p>If a user connects to a server with full encryption, but the
page then refers to an external resource that has an expired
certificate, then the user agent will act as if the resource was
unavailable, possibly also reporting the problem to the user. If
the user agent instead allowed the resource to be used, then an
attacker could just look for "secure" sites that used resources
from a different host and only apply man-in-the-middle attacks to
that host, for example taking over scripts in the page.</p>
<p>If a user bookmarks a site that uses a CA-signed certificate,
and then later revisits that site directly but the site has started
using a self-signed certificate, the user agent could warn the user
that a man-in-the-middle attack is likely underway, instead of
simply acting as if the page was not encrypted.</p>
</div>
<h4 id="content-type-sniffing">Determining the type of a resource</h4>
<p>The <dfn title="Content-Type">Content-Type metadata</dfn> of a
resource must be obtained and interpreted in a manner consistent
with the requirements of the Content-Type Processing Model
specification. <a href="#refsMIMESNIFF">[MIMESNIFF]</a></p>
<p>The <dfn>algorithm for extracting an encoding from a
Content-Type</dfn>, given a string <var title="">s</var>, is given
in the Content-Type Processing Model specification. It either
returns an encoding or nothing. <a
href="#refsMIMESNIFF">[MIMESNIFF]</a></p>
<p>The <dfn title="Content-Type sniffing">sniffed type of a
resource</dfn> must be found in a manner consistent with the
requirements given in the Content-Type Processing Model
specification for finding that <i>sniffed type</i>. <a
href="#refsMIMESNIFF">[MIMESNIFF]</a></p>
<p>The <dfn title="Content-Type sniffing: image">rules for sniffing
images specifically</dfn> and the <dfn title="Content-Type sniffing:
text or binary">rules for distingushing if a resource is text or
binary</dfn> are also defined in the Content-Type Processing Model
specification. Both sets of rules return a <span>MIME type</span> as
their result. <a href="#refsMIMESNIFF">[MIMESNIFF]</a></p>
<p class="warning">It is imperative that the rules in the
Content-Type Processing Model specification be followed
exactly. When a user agent uses different heuristics for content
type detection than the server expects, security problems can
occur. For more details, see the Content-Type Processing Model
specification. <a href="#refsMIMESNIFF">[MIMESNIFF]</a></p>
</div>
<h3>Common DOM interfaces</h3>
<h4>Reflecting content attributes in IDL attributes</h4>
<p>Some IDL attributes are defined to <dfn>reflect</dfn> a
particular content attribute. This means that on getting, the IDL
attribute returns the current value of the content attribute, and on
setting, the IDL attribute changes the value of the content
attribute to the given value.</p>
<!-- v2 for completeness: (also search for REFLECTIDL)
<p class="note">A list of <span>reflecting IDL attributes</span> and
their corresponding content attributes is given in the index.</p>
-->
<div class="impl">
<p>In general, on getting, if the content attribute is not present,
the IDL attribute must act as if the content attribute's value is
the empty string; and on setting, if the content attribute is not
present, it must first be added.</p>
<p>If a reflecting IDL attribute is a <code>DOMString</code>
attribute whose content attribute is defined to contain a
<span>URL</span>, then on getting, the IDL attribute must <span
title="resolve a url">resolve</span> the value of the content
attribute relative to the element and return the resulting
<span>absolute URL</span> if that was successful, or the empty
string otherwise; and on setting, must set the content attribute to
the specified literal value. If the content attribute is absent, the
IDL attribute must return the default value, if the content
attribute has one, or else the empty string.</p>
<p>If a reflecting IDL attribute is a <code>DOMString</code>
attribute whose content attribute is defined to contain one or more
<span title="URL">URLs</span>, then on getting, the IDL attribute
must <span title="split a string on spaces">split the content
attribute on spaces</span> and return the concatenation of <span
title="resolve a URL">resolving</span> each token URL to an
<span>absolute URL</span> relative to the element, with a single
U+0020 SPACE character between each URL, ignoring any tokens that
did not resolve successfully. If the content attribute is absent,
the IDL attribute must return the default value, if the content
attribute has one, or else the empty string. On setting, the IDL
attribute must set the content attribute to the specified literal
value.</p>
<p>If a reflecting IDL attribute is a <code>DOMString</code> whose
content attribute is an <span>enumerated attribute</span>, and the
IDL attribute is <dfn>limited to only known values</dfn>, then, on
getting, the IDL attribute must return the conforming value
associated with the state the attribute is in (in its canonical
case), or the empty string if the attribute is in a state that has
no associated keyword value; and on setting, if the new value is an
<span>ASCII case-insensitive</span> match for one of the keywords
given for that attribute, then the content attribute must be set to
the conforming value associated with the state that the attribute
would be in if set to the given new value, otherwise, if the new
value is the empty string, then the content attribute must be
removed, otherwise, the setter must raise a <code>SYNTAX_ERR</code>
exception.</p>
<p>If a reflecting IDL attribute is a <code>DOMString</code> but
doesn't fall into any of the above categories, then the getting and
setting must be done in a transparent, case-preserving manner.</p>
<p>If a reflecting IDL attribute is a <span>boolean
attribute</span>, then on getting the IDL attribute must return true
if the attribute is set, and false if it is absent. On setting, the
content attribute must be removed if the IDL attribute is set to
false, and must be set to have the same value as its name if the IDL
attribute is set to true. (This corresponds to the rules for <span
title="boolean attribute">boolean content attributes</span>.)</p>
<p>If a reflecting IDL attribute is a signed integer type
(<code>long</code>) then, on getting, the content attribute must be
parsed according to the <span title="rules for parsing
integers">rules for parsing signed integers</span>, and if that is
successful, and the value is in the range of the IDL attribute's
type, the resulting value must be returned. If, on the other hand,
it fails or returns an out of range value, or if the attribute is
absent, then the default value must be returned instead, or 0 if
there is no default value. On setting, the given value must be
converted to the shortest possible string representing the number as
a <span>valid integer</span> and then that string must be used as
the new content attribute value.</p>
<p>If a reflecting IDL attribute is a signed integer type
(<code>long</code>) that is <dfn>limited to only non-negative
numbers</dfn> then, on getting, the content attribute must be parsed
according to the <span>rules for parsing non-negative
integers</span>, and if that is successful, and the value is in the
range of the IDL attribute's type, the resulting value must be
returned. If, on the other hand, it fails or returns an out of range
value, or if the attribute is absent, the default value must be
returned instead, or −1 if there is no default value. On
setting, if the value is negative, the user agent must fire an
<code>INDEX_SIZE_ERR</code> exception. Otherwise, the given value
must be converted to the shortest possible string representing the
number as a <span>valid non-negative integer</span> and then that
string must be used as the new content attribute value.</p>
<p>If a reflecting IDL attribute is an <em>unsigned</em> integer
type (<code>unsigned long</code>) then, on getting, the content
attribute must be parsed according to the <span>rules for parsing
non-negative integers</span>, and if that is successful, and the
value is in the range of the IDL attribute's type, the resulting
value must be returned. If, on the other hand, it fails or returns
an out of range value, or if the attribute is absent, the default
value must be returned instead, or 0 if there is no default
value. On setting, the given value must be converted to the shortest
possible string representing the number as a <span>valid
non-negative integer</span> and then that string must be used as the
new content attribute value.</p>
<p>If a reflecting IDL attribute is an unsigned integer type
(<code>unsigned long</code>) that is <dfn>limited to only
non-negative numbers greater than zero</dfn>, then the behavior is
similar to the previous case, but zero is not allowed. On getting,
the content attribute must first be parsed according to the
<span>rules for parsing non-negative integers</span>, and if that is
successful, and the value is in the range of the IDL attribute's
type, the resulting value must be returned. If, on the other hand,
it fails or returns an out of range value, or if the attribute is
absent, the default value must be returned instead, or 1 if there is
no default value. On setting, if the value is zero, the user agent
must fire an <code>INDEX_SIZE_ERR</code> exception. Otherwise, the
given value must be converted to the shortest possible string
representing the number as a <span>valid non-negative integer</span>
and then that string must be used as the new content attribute
value.</p>
<p>If a reflecting IDL attribute is a floating point number type
(<code>float</code>), then, on getting, the content attribute must
be parsed according to the <span>rules for parsing floating point
number values</span>, and if that is successful, the resulting value
must be returned. If, on the other hand, it fails, or if the
attribute is absent, the default value must be returned instead, or
0.0 if there is no default value. On setting, the given value must
be converted to the <span>best representation of the number as a
floating point number</span> and then that string must be used as
the new content attribute value.</p>
<p class="note">The values Infinity and Not-a-Number (NaN) values
throw an exception on setting, as <a href="#float-nan">defined
earlier</a>.</p>
<p>If a reflecting IDL attribute is of the type
<code>DOMTokenList</code> or <code>DOMSettableTokenList</code>, then
on getting it must return a <code>DOMTokenList</code> or
<code>DOMSettableTokenList</code> object (as appropriate) whose
underlying string is the element's corresponding content
attribute. When the object mutates its underlying string, the
content attribute must itself be immediately mutated. When the
attribute is absent, then the string represented by the object is
the empty string; when the object mutates this empty string, the
user agent must add the corresponding content attribute, with its
value set to the value it would have been set to after mutating the
empty string. The same <code>DOMTokenList</code> or
<code>DOMSettableTokenList</code> object must be returned every time
for each attribute.</p>
<div class="example">
<p>If an element with no attributes has its <code
title="dom-tokenlist-remove">element.classList.remove()</code>
method invoked, the underlying string won't be changed, since the
result of removing any token from the empty string is still the
empty string. However, if the <code
title="dom-tokenlist-add">element.classList.add()</code> method is
then invoked, a <code title="attr-class">class</code> attribute
will be added to the element with the value of the token to be
added.</p>
</div>
<p>If a reflecting IDL attribute has the type
<code>HTMLElement</code>, or an interface that descends from
<code>HTMLElement</code>, then, on getting, it must run the
following algorithm (stopping at the first point where a value is
returned):</p>
<ol>
<li>If the corresponding content attribute is absent, then the
IDL attribute must return null.</li>
<li>Let <var title="">candidate</var> be the element that the <code
title="">document.getElementById()</code> method would find if it
was passed as its argument the current value of the corresponding
content attribute.</li>
<li>If <var title="">candidate</var> is null, or if it is not
type-compatible with the IDL attribute, then the IDL attribute must
return null.</li>
<li>Otherwise, it must return <var title="">candidate</var>.</li>
</ol>
<p>On setting, if the given element has an <code
title="attr-id">id</code> attribute, then the content attribute must
be set to the value of that <code title="attr-id">id</code>
attribute. Otherwise, the IDL attribute must be set to the empty
string.</p>
</div>
<h4>Collections</h4>
<p>The <code>HTMLCollection</code>, <code>HTMLAllCollection</code>,
<code>HTMLFormControlsCollection</code>,
<code>HTMLOptionsCollection</code>, and
<code>HTMLPropertiesCollection</code> interfaces represent various
lists of DOM nodes. Collectively, objects implementing these
interfaces are called <dfn>collections</dfn>.</p>
<p>When a <span title="collections">collection</span> is created, a
filter and a root are associated with the collection.</p>
<p class="example">For example, when the <code>HTMLCollection</code>
object for the <code
title="dom-document-images">document.images</code> attribute is
created, it is associated with a filter that selects only
<code>img</code> elements, and rooted at the root of the
document.</p>
<p>The <span title="collections">collection</span> then <dfn
title="represented by the collection">represents</dfn> a
<span>live</span> view of the subtree rooted at the collection's
root, containing only nodes that match the given filter. The view is
linear. <span class="impl">In the absence of specific requirements
to the contrary, the nodes within the collection must be sorted in
<span>tree order</span>.</span></p>
<div class="impl">
<p class="note">The <code title="dom-table-rows">rows</code> list is
not in tree order.</p>
<p>An attribute that returns a collection must return the same
object every time it is retrieved.</p>
</div>
<h5>HTMLCollection</h5>
<p>The <code>HTMLCollection</code> interface represents a generic
<span title="collections">collection</span> of elements.</p>
<pre class="idl">interface <dfn>HTMLCollection</dfn> {
readonly attribute unsigned long <span title="dom-HTMLCollection-length">length</span>;
caller getter object <span title="dom-HTMLCollection-item">item</span>(in unsigned long index); // only returns Element
caller getter object <span title="dom-HTMLCollection-namedItem">namedItem</span>(in DOMString name); // only returns Element<!--
(removed on the assuption that browsers will remove support:)
https://bugs.webkit.org/show_bug.cgi?id=30695
https://bugs.opera.com/browse/CORE-25171
<span>HTMLAllCollection</span> <span title="dom-HTMLCollection-tags">tags</span>(in DOMString tagName);-->
};</pre>
<dl class="domintro">
<dt><var title="">collection</var> . <code title="dom-HTMLCollection-length">length</code></dt>
<dd>
<p>Returns the number of elements in the collection.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLCollection-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">collection</var>[<var title="">index</var>]</dt>
<dt><var title="">collection</var>(<var title="">index</var>)</dt>
<dd>
<p>Returns the item with index <var title="">index</var> from the collection. The items are sorted in <span>tree order</span>.</p>
<p>Returns null if <var title="">index</var> is out of range.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLCollection-item">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">collection</var>[<var title="">name</var>]</dt>
<dt><var title="">collection</var>(<var title="">name</var>)</dt>
<dd>
<p>Returns the first item with <span title="concept-id">ID</span> or name <var title="">name</var>
from the collection.</p>
<p>Returns null if no element with that <span title="concept-id">ID</span> or name could be found.</p>
<p>Only <code>a</code>, <code>applet</code>, <code>area</code>,
<code>embed</code>, <code>form</code>, <code>frame</code>,
<code>frameset</code>, <code>iframe</code>, <code>img</code>, and
<code>object</code> elements can have a name for the purpose of
this method; their name is given by the value of their <code
title="">name</code> attribute.</p>
</dd>
<!--(see IDL)
<dt><var title="">collection</var> = <var title="">collection</var> . <code title="dom-HTMLCollection-tags">tags</code>(<var title="">tagName</var>)</dt>
<dd>
<p>Returns a collection that is a filtered view of the current collection, containing only elements with the given tag name.</p>
</dd>
-->
</dl>
<div class="impl">
<p>The object's <span>indices of the supported indexed
properties</span> are the numbers in the range zero to one less than
the number of nodes <span>represented by the collection</span>. If
there are no such elements, then there are no <span>supported
indexed properties</span>.</p>
<p>The <dfn
title="dom-HTMLCollection-length"><code>length</code></dfn>
attribute must return the number of nodes <span>represented by the
collection</span>.</p>
<p>The <dfn title="dom-HTMLCollection-item"><code>item(<var
title="">index</var>)</code></dfn> method must return the <var
title="">index</var>th node in the collection. If there is no <var
title="">index</var>th node in the collection, then the method must
return null.</p>
<p>The <span>names of the supported named properties</span> consist
of the values of the <code title="">name</code> attributes of each
<code>a</code>, <code>applet</code>, <code>area</code>,
<code>embed</code>, <code>form</code>, <code>frame</code>,
<code>frameset</code>, <code>iframe</code>, <code>img</code>, and
<code>object</code> element <span>represented by the
collection</span> with a <code title="">name</code> attribute, plus
the list of IDs that the elements <span>represented by the
collection</span> have.</p>
<p>The <dfn
title="dom-HTMLCollection-namedItem"><code>namedItem(<var
title="">key</var>)</code></dfn> method must return the first node
in the collection that matches the following requirements:</p>
<ul>
<li>It is an <code>a</code>, <code>applet</code>,
<code>area</code>, <code>embed</code>, <code>form</code>,
<code>frame</code>, <code>frameset</code>, <code>iframe</code>,
<code>img</code>, or <code>object</code> element with a <code
title="">name</code> attribute equal to <var title="">key</var>,
or,</li>
<li>It is an element with an <span title="concept-id">ID</span>
equal to <var title="">key</var>.</li>
</ul>
<p>If no such elements are found, then the method must return
null.</p>
<!--(see IDL)
<p>The <dfn title="dom-HTMLCollection-tags"><code>tags(<var
title="">tagName</var>)</code></dfn> method must return an
<code>HTMLAllCollection</code> rooted at the same node as the
<code>HTMLCollection</code> object on which the method was invoked,
whose filter matches only <span>HTML elements</span> whose local
name is the <var title="">tagName</var> argument and that already
match the filter of the <code>HTMLCollection</code> object on which
the method was invoked. In <span>HTML documents</span>, the argument
must first be <span>converted to ASCII lowercase</span>.</p>
-->
</div>
<h5>HTMLAllCollection</h5>
<p>The <code>HTMLAllCollection</code> interface represents a generic
<span title="collections">collection</span> of elements just like
<code>HTMLCollection</code>, with the exception that its <code
title="dom-HTMLAllCollection-namedItem">namedItem()</code> method
returns an <code>HTMLCollection</code> object when there are
multiple matching elements.</p>
<pre class="idl">interface <dfn>HTMLAllCollection</dfn> : <span>HTMLCollection</span> {
// inherits <span title="dom-HTMLCollection-length">length</span> and <span title="dom-HTMLCollection-item">item</span>()
caller getter object <span title="dom-HTMLAllCollection-namedItem">namedItem</span>(in DOMString name); // overrides inherited namedItem()
<span>HTMLAllCollection</span> <span title="dom-HTMLAllCollection-tags">tags</span>(in DOMString tagName);
};</pre>
<dl class="domintro">
<dt><var title="">collection</var> . <code title="dom-HTMLCollection-length">length</code></dt>
<dd>
<p>Returns the number of elements in the collection.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLCollection-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">collection</var>[<var title="">index</var>]</dt>
<dt><var title="">collection</var>(<var title="">index</var>)</dt>
<dd>
<p>Returns the item with index <var title="">index</var> from the collection. The items are sorted in <span>tree order</span>.</p>
<p>Returns null if <var title="">index</var> is out of range.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLAllCollection-namedItem">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">collection</var> = <var title="">collection</var> . <code title="dom-HTMLAllCollection-namedItem">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">collection</var>[<var title="">name</var>]</dt>
<dt><var title="">collection</var>(<var title="">name</var>)</dt>
<dd>
<p>Returns the item with <span title="concept-id">ID</span> or name <var title="">name</var> from the collection.</p>
<p>If there are multiple matching items, then an <code>HTMLAllCollection</code> object containing all those elements is returned.</p>
<p>Returns null if no element with that <span title="concept-id">ID</span> or name could be found.</p>
<p>Only <code>a</code>, <code>applet</code>, <code>area</code>,
<code>embed</code>, <code>form</code>, <code>frame</code>,
<code>frameset</code>, <code>iframe</code>, <code>img</code>, and
<code>object</code> elements can have a name for the purpose of
this method; their name is given by the value of their <code
title="">name</code> attribute.</p>
</dd>
<dt><var title="">collection</var> = <var title="">collection</var> . <code title="dom-HTMLAllCollection-tags">tags</code>(<var title="">tagName</var>)</dt>
<dd>
<p>Returns a collection that is a filtered view of the current collection, containing only elements with the given tag name.</p>
</dd>
</dl>
<div class="impl">
<p>The object's <span>indices of the supported indexed
properties</span> and <span>names of the supported named
properties</span> are as defined for <code>HTMLCollection</code>
objects.</p>
<p>The <dfn
title="dom-HTMLAllCollection-namedItem"><code>namedItem(<var
title="">key</var>)</code></dfn> method must act according to the
following algorithm:</p>
<ol>
<li>
<p>Let <var title="">collection</var> be an
<code>HTMLAllCollection</code> object rooted at the same node as
the <code>HTMLAllCollection</code> object on which the method was
invoked, whose filter matches only only elements that already
match the filter of the <code>HTMLAllCollection</code> object on
which the method was invoked and that are either:</p>
<ul>
<li><code>a</code>, <code>applet</code>, <code>area</code>,
<code>embed</code>, <code>form</code>, <code>frame</code>,
<code>frameset</code>, <code>iframe</code>, <code>img</code>, or
<code>object</code> elements with a <code title="">name</code>
attribute equal to <var title="">key</var>, or,</li>
<li>elements with an <span title="concept-id">ID</span> equal to
<var title="">key</var>.</li>
</ul>
</li>
<li>If, at the time the method is called, there is exactly one node
in <var title="">collection</var>, then return that node and stop
the algorithm.</li>
<li>Otherwise, if, at the time the method is called, <var
title="">collection</var> is empty, return null and stop the
algorithm.</li>
<li>Otherwise, return <var title="">collection</var>.</li>
</ol>
<p>The <dfn title="dom-HTMLAllCollection-tags"><code>tags(<var
title="">tagName</var>)</code></dfn> method must return an
<code>HTMLAllCollection</code> rooted at the same node as the
<code>HTMLAllCollection</code> object on which the method was
invoked, whose filter matches only <span>HTML elements</span> whose
local name is the <var title="">tagName</var> argument and that
already match the filter of the <code>HTMLAllCollection</code>
object on which the method was invoked. In <span>HTML
documents</span>, the argument must first be <span>converted to
ASCII lowercase</span>.</p>
</div>
<h5>HTMLFormControlsCollection</h5>
<p>The <code>HTMLFormControlsCollection</code> interface represents
a <span title="collections">collection</span> of <span
title="category-listed">listed</span> elements in <code>form</code>
and <code>fieldset</code> elements.</p>
<pre class="idl">interface <dfn>HTMLFormControlsCollection</dfn> : <span>HTMLCollection</span> {
// inherits <span title="dom-HTMLCollection-length">length</span> and <span title="dom-HTMLCollection-item">item</span>()
caller getter object <span title="dom-HTMLFormControlsCollection-namedItem">namedItem</span>(in DOMString name); // overrides inherited namedItem()
};
interface <dfn>RadioNodeList</dfn> : <span>NodeList</span> {
attribute DOMString <span title="dom-RadioNodeList-value">value</span>;
};</pre>
<dl class="domintro">
<dt><var title="">collection</var> . <code title="dom-HTMLCollection-length">length</code></dt>
<dd>
<p>Returns the number of elements in the collection.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLCollection-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">collection</var>[<var title="">index</var>]</dt>
<dt><var title="">collection</var>(<var title="">index</var>)</dt>
<dd>
<p>Returns the item with index <var title="">index</var> from the collection. The items are sorted in <span>tree order</span>.</p>
<p>Returns null if <var title="">index</var> is out of range.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLFormControlsCollection-namedItem">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">radioNodeList</var> = <var title="">collection</var> . <code title="dom-HTMLFormControlsCollection-namedItem">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">collection</var>[<var title="">name</var>]</dt>
<dt><var title="">collection</var>(<var title="">name</var>)</dt>
<dd>
<p>Returns the item with <span title="concept-id">ID</span> or <code title="attr-fe-name">name</code> <var title="">name</var> from the collection.</p>
<p>If there are multiple matching items, then a <code>RadioNodeList</code> object containing all those elements is returned.</p>
<p>Returns null if no element with that <span title="concept-id">ID</span> or <code title="attr-fe-name">name</code> could be found.</p>
</dd>
<dt><var title="">radioNodeList</var> . <var title="">value</var> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the value of the first checked radio button represented by the object.</p>
<p>Can be set, to check the first radio button with the given value represented by the object.</p>
</dd>
</dl>
<div class="impl">
<p>The object's <span>indices of the supported indexed
properties</span> are as defined for <code>HTMLCollection</code>
objects.</p>
<p>The <span>names of the supported named properties</span> consist
of the values of all the <code title="attr-id">id</code> and <code
title="attr-fe-name">name</code> attributes of all the elements
<span>represented by the collection</span>.</p>
<p>The <dfn
title="dom-HTMLFormControlsCollection-namedItem"><code>namedItem(<var
title="">name</var>)</code></dfn> method must act according to the
following algorithm:</p>
<ol>
<li>If, at the time the method is called, there is exactly one node
in the collection that has either an <code
title="attr-id">id</code> attribute or a <code
title="attr-fe-name">name</code> attribute equal to <var
title="">name</var>, then return that node and stop the
algorithm.</li>
<li>Otherwise, if there are no nodes in the collection that have
either an <code title="attr-id">id</code> attribute or a <code
title="attr-fe-name">name</code> attribute equal to <var
title="">name</var>, then return null and stop the algorithm.</li>
<li>Otherwise, create a <code>RadioNodeList</code> object
representing a live view of the
<code>HTMLFormControlsCollection</code> object, further filtered so
that the only nodes in the <code>RadioNodeList</code> object are
those that have either an <code title="attr-id">id</code> attribute
or a <code title="attr-fe-name">name</code> attribute equal to <var
title="">name</var>. The nodes in the <code>RadioNodeList</code>
object must be sorted in <span>tree order</span>.</li>
<li>Return that <code>RadioNodeList</code> object.</li>
</ol>
<hr>
<p>Members of the <code>RadioNodeList</code> interface inherited
from the <code>NodeList</code> interface must behave as they would
on a <code>NodeList</code> object.</p>
<p>The <dfn title="dom-RadioNodeList-value"><code>value</code></dfn>
IDL attribute on the <code>RadioNodeList</code> object, on getting,
must return the value returned by running the following steps:</p>
<ol>
<li><p>Let <var title="">element</var> be the first element in
<span>tree order</span> represented by the
<code>RadioNodeList</code> object that is an <code>input</code>
element whose <code title="attr-input-type">type</code> attribute
is in the <span title="attr-input-type-radio">Radio Button</span>
state and whose <span title="concept-fe-checked">checkedness</span>
is true. Otherwise, let it be null.</p></li>
<li><p>If <var title="">element</var> is null, or if it is an
element with no <code title="attr-input-value">value</code>
attribute, return the empty string.</p></li>
<li><p>Otherwise, return the value of <var title="">element</var>'s
<code title="attr-input-value">value</code> attribute.</p></li>
</ol>
<p>On setting, the <code
title="dom-RadioNodeList-value">value</code> IDL attribute must run
the following steps:</p>
<ol>
<li><p>Let <var title="">element</var> be the first element in
<span>tree order</span> represented by the
<code>RadioNodeList</code> object that is an <code>input</code>
element whose <code title="attr-input-type">type</code> attribute
is in the <span title="attr-input-type-radio">Radio Button</span>
state and whose <code title="attr-input-value">value</code> content
attribute is present and equal to the new value, if any. Otherwise,
let it be null.</p></li>
<li><p>If <var title="">element</var> is not null, then set its
<span title="concept-fe-checked">checkedness</span> to true.</p>
</ol>
<!--
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E...%0A%3Cform%20name%3D%22a%22%3E%3Cinput%20id%3D%22x%22%20name%3D%22y%22%3E%3Cinput%20name%3D%22x%22%20id%3D%22y%22%3E%3C/form%3E%0A%3Cscript%3E%0A%20%20var%20x%3B%0A%20%20w%28x%20%3D%20document.forms%5B%27a%27%5D%5B%27x%27%5D%29%3B%0A%20%20w%28x.length%29%3B%0A%20%20x%5B0%5D.parentNode.removeChild%28x%5B0%5D%29%3B%0A%20%20w%28x.length%29%3B%0A%20%20w%28x%20%3D%3D%20document.forms%5B%27a%27%5D%5B%27x%27%5D%29%3B%0A%3C/script%3E%0A
-->
</div>
<h5>HTMLOptionsCollection</h5>
<p>The <code>HTMLOptionsCollection</code> interface represents a
list of <code>option</code> elements. It is always rooted on a
<code>select</code> element and has attributes and methods that
manipulate that element's descendants.</p>
<pre class="idl">interface <dfn>HTMLOptionsCollection</dfn> : <span>HTMLCollection</span> {
// inherits <span title="dom-HTMLCollection-item">item</span>()
attribute unsigned long <span title="dom-HTMLOptionsCollection-length">length</span>; // overrides inherited length
caller getter object <span title="dom-HTMLOptionsCollection-namedItem">namedItem</span>(in DOMString name); // overrides inherited namedItem()
void <span title="dom-HTMLOptionsCollection-add">add</span>(in <span>HTMLElement</span> element, in optional <span>HTMLElement</span> before);
void <span title="dom-HTMLOptionsCollection-add">add</span>(in <span>HTMLElement</span> element, in long before);
void <span title="dom-HTMLOptionsCollection-remove">remove</span>(in long index);
};</pre>
<dl class="domintro">
<dt><var title="">collection</var> . <code title="dom-HTMLOptionsCollection-length">length</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the number of elements in the collection.</p>
<p>When set to a smaller number, truncates the number of <code>option</code> elements in the corresponding container.</p>
<p>When set to a greater number, adds new blank <code>option</code> elements to that container.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLCollection-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">collection</var>[<var title="">index</var>]</dt>
<dt><var title="">collection</var>(<var title="">index</var>)</dt>
<dd>
<p>Returns the item with index <var title="">index</var> from the collection. The items are sorted in <span>tree order</span>.</p>
<p>Returns null if <var title="">index</var> is out of range.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLOptionsCollection-namedItem">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">nodeList</var> = <var title="">collection</var> . <code title="dom-HTMLOptionsCollection-namedItem">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">collection</var>[<var title="">name</var>]</dt>
<dt><var title="">collection</var>(<var title="">name</var>)</dt>
<dd>
<p>Returns the item with <span title="concept-id">ID</span> or <code title="attr-option-name">name</code> <var title="">name</var> from the collection.</p>
<p>If there are multiple matching items, then a <code>NodeList</code> object containing all those elements is returned.</p>
<p>Returns null if no element with that <span title="concept-id">ID</span> could be found.</p>
</dd>
<dt><var title="">collection</var> . <code title="dom-HTMLOptionsCollection-add">add</code>(<var title="">element</var> [, <var title="">before</var> ] )</dt>
<dd>
<p>Inserts <var title="">element</var> before the node given by <var title="">before</var>.</p>
<p>The <var title="">before</var> argument can be a number, in
which case <var title="">element</var> is inserted before the item
with that number, or an element from the collection, in which case
<var title="">element</var> is inserted before that element.</p>
<p>If <var title="">before</var> is omitted, null, or a number out
of range, then <var title="">element</var> will be added at the
end of the list.</p>
<p>This method will throw a <code>HIERARCHY_REQUEST_ERR</code>
exception if <var title="">element</var> is an ancestor of the
element into which it is to be inserted. If <var
title="">element</var> is not an <code>option</code> or
<code>optgroup</code> element, then the method does nothing.</p>
</dd>
</dl>
<div class="impl">
<p>The object's <span>indices of the supported indexed
properties</span> are as defined for <code>HTMLCollection</code>
objects.</p>
<p>On getting, the <dfn
title="dom-HTMLOptionsCollection-length"><code>length</code></dfn>
attribute must return the number of nodes <span>represented by the
collection</span>.</p>
<p>On setting, the behavior depends on whether the new value is
equal to, greater than, or less than the number of nodes
<span>represented by the collection</span> at that time. If the
number is the same, then setting the attribute must do nothing. If
the new value is greater, then <var title="">n</var> new
<code>option</code> elements with no attributes and no child nodes
must be appended to the <code>select</code> element on which the
<code>HTMLOptionsCollection</code> is rooted, where <var
title="">n</var> is the difference between the two numbers (new
value minus old value). If the new value is lower, then the last
<var title="">n</var> nodes in the collection must be removed from
their parent nodes, where <var title="">n</var> is the difference
between the two numbers (old value minus new value).</p>
<p class="note">Setting <code
title="dom-HTMLOptionsCollection-length">length</code> never removes
or adds any <code>optgroup</code> elements, and never adds new
children to existing <code>optgroup</code> elements (though it can
remove children from them).</p>
<p>The <span>names of the supported named properties</span> consist
of the values of all the <code title="attr-id">id</code> and <code
title="attr-option-name">name</code> attributes of all the elements
<span>represented by the collection</span>.</p>
<p>The <dfn
title="dom-HTMLOptionsCollection-namedItem"><code>namedItem(<var
title="">name</var>)</code></dfn> method must act according to the
following algorithm:</p>
<ol>
<li>If, at the time the method is called, there is exactly one node
in the collection that has either an <code
title="attr-id">id</code> attribute or a <code
title="attr-option-name">name</code> attribute equal to <var
title="">name</var>, then return that node and stop the
algorithm.</li>
<li>Otherwise, if there are no nodes in the collection that have
either an <code title="attr-id">id</code> attribute or a <code
title="attr-option-name">name</code> attribute equal to <var
title="">name</var>, then return null and stop the algorithm.</li>
<!-- IE returns an HTMLCollection instead; we may need to change to that for compat -->
<li>Otherwise, create a <code>NodeList</code> object representing a
live view of the <code>HTMLOptionsCollection</code> object, further
filtered so that the only nodes in the <code>NodeList</code> object
are those that have either an <code title="attr-id">id</code>
attribute or a <code title="attr-option-name">name</code> attribute
equal to <var title="">name</var>. The nodes in the
<code>NodeList</code> object must be sorted in <span>tree
order</span>.</li>
<li>Return that <code>NodeList</code> object.</li>
</ol>
<p>The <dfn title="dom-HTMLOptionsCollection-add"><code>add(<var
title="">element</var>, <var title="">before</var>)</code></dfn>
method must act according to the following algorithm:</p>
<ol>
<li><p>If <var title="">element</var> is not an <code>option</code>
or <code>optgroup</code> element, then return and abort these
steps.</li>
<li><p>If <var title="">element</var> is an ancestor of the
<code>select</code> element on which the
<code>HTMLOptionsCollection</code> is rooted, then throw a
<code>HIERARCHY_REQUEST_ERR</code> exception.</li>
<li><p>If <var title="">before</var> is an element, but that
element isn't a descendant of the <code>select</code> element on
which the <code>HTMLOptionsCollection</code> is rooted, then throw
a <code>NOT_FOUND_ERR</code> exception.</p></li>
<li><p>If <var title="">element</var> and <var
title="">before</var> are the same element, then return and abort
these steps.</li>
<li><p>If <var title="">before</var> is a node, then let <var
title="">reference</var> be that node. Otherwise, if <var
title="">before</var> is an integer, and there is a <var
title="">before</var>th node in the collection, let <var
title="">reference</var> be that node. Otherwise, let <var
title="">reference</var> be null.</p></li>
<li><p>If <var title="">reference</var> is not null, let <var
title="">parent</var> be the parent node of <var
title="">reference</var>. Otherwise, let <var title="">parent</var>
be the <code>select</code> element on which the
<code>HTMLOptionsCollection</code> is rooted.</p></li>
<li><p>Act as if the DOM Core <code
title="dom-insertBefore">insertBefore()</code> method was invoked
on the <var title="">parent</var> node, with <var
title="">element</var> as the first argument and <var
title="">reference</var> as the second argument.</p>
</ol>
<p>The <dfn
title="dom-HTMLOptionsCollection-remove"><code>remove(<var
title="">index</var>)</code></dfn> method must act according to
the following algorithm:</p>
<ol>
<li><p>If the number of nodes <span>represented by the
collection</span> is zero, abort these steps.</li>
<li><p>If <var title="">index</var> is not a number greater than or
equal to 0 and less than the number of nodes <span>represented by
the collection</span>, let <var title="">element</var> be the first
element in the collection. Otherwise, let <var
title="">element</var> be the <var title="">index</var>th element
in the collection.</p></li>
<li><p>Remove <var title="">element</var> from its parent
node.</p></li>
</ol>
<!-- see also http://ln.hixie.ch/?start=1161042744&count=1 -->
</div>
<h5>HTMLPropertiesCollection</h5>
<p>The <code>HTMLPropertiesCollection</code> interface represents a
<span title="collections">collection</span> of elements that add
name-value pairs to a particular <span
title="concept-item">item</span> in the <span>microdata</span>
model.</p>
<pre class="idl">interface <dfn>HTMLPropertiesCollection</dfn> : <span>HTMLCollection</span> {
// inherits <span title="dom-HTMLCollection-length">length</span> and <span title="dom-HTMLCollection-item">item</span>()
caller getter <span>PropertyNodeList</span> <span title="dom-HTMLPropertiesCollection-namedItem">namedItem</span>(in DOMString name); // overrides inherited namedItem()
readonly attribute <span>DOMStringList</span> <span title="dom-HTMLPropertiesCollection-names">names</span>;
};
typedef sequence<any> <dfn>PropertyValueArray</dfn>;
interface <dfn>PropertyNodeList</dfn> : <span>NodeList</span> {
readonly attribute <span>PropertyValueArray</span> <span title="dom-PropertyNodeList-values">values</span>;
};</pre>
<dl class="domintro">
<dt><var title="">collection</var> . <code title="dom-HTMLCollection-length">length</code></dt>
<dd>
<p>Returns the number of elements in the collection.</p>
</dd>
<dt><var title="">element</var> = <var title="">collection</var> . <code title="dom-HTMLCollection-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">collection</var>[<var title="">index</var>]</dt>
<dt><var title="">collection</var>(<var title="">index</var>)</dt>
<dd>
<p>Returns the element with index <var title="">index</var> from the collection. The items are sorted in <span>tree order</span>.</p>
<p>Returns null if <var title="">index</var> is out of range.</p>
</dd>
<dt><var title="">propertyNodeList</var> = <var title="">collection</var> . <code title="dom-HTMLPropertiesCollection-namedItem">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">collection</var>[<var title="">name</var>]</dt>
<dt><var title="">collection</var>(<var title="">name</var>)</dt>
<dd>
<p>Returns a <code>PropertyNodeList</code> object containing any elements that add a property named <var title="">name</var>.</p>
</dd>
<dt><var title="">collection</var> . <code title="dom-HTMLPropertiesCollection-names">names</code></dt>
<dd>
<p>Returns a <code>DOMStringList</code> with the <span>property names</span> of the elements in the collection.</p>
</dd>
<dt><var title="">propertyNodeList</var> . <code title="dom-PropertyNodeList-values">values</code></dt>
<dd>
<p>Returns an array of the various values that the relevant elements have.</p>
</dd>
</dl>
<div class="impl">
<p>The object's <span>indices of the supported indexed
properties</span> are as defined for <code>HTMLCollection</code>
objects.</p>
<p>The <span>names of the supported named properties</span> consist
of the <span>property names</span> of all the elements
<span>represented by the collection</span>.</p>
<p>The <dfn
title="dom-HTMLPropertiesCollection-names"><code>names</code></dfn>
attribute must return a live <code>DOMStringList</code> object
giving the <span>property names</span> of all the elements
<span>represented by the collection</span>, listed in <span>tree
order</span>, but with duplicates removed, leaving only the first
occurrence of each name. The same object must be returned each
time.</p>
<p>The <dfn
title="dom-HTMLPropertiesCollection-namedItem"><code>namedItem(<var
title="">name</var>)</code></dfn> method must return a
<code>PropertyNodeList</code> object representing a live view of the
<code>HTMLPropertiesCollection</code> object, further filtered so that
the only nodes in the <code>PropertyNodeList</code> object are those
that have a <span title="property names">property name</span> equal
to <var title="">name</var>. The nodes in the
<code>PropertyNodeList</code> object must be sorted in <span>tree
order</span>, and the same object must be returned each time a
particular <var title="">name</var> is queried.</p>
<hr>
<p>Members of the <code>PropertyNodeList</code> interface inherited
from the <code>NodeList</code> interface must behave as they would
on a <code>NodeList</code> object.</p>
<p>The <dfn
title="dom-PropertyNodeList-values"><code>values</code></dfn>
IDL attribute on the <code>PropertyNodeList</code> object, on
getting, must return a newly constructed array whose values are the
values obtained from the <code
title="dom-itemValue">itemValue</code> DOM property of each of the
elements represented by the object, in <span>tree order</span>.</p>
</div>
<h4>DOMTokenList</h4>
<p>The <code>DOMTokenList</code> interface represents an interface
to an underlying string that consists of a <span>set of
space-separated tokens</span>.</p>
<p class="note"><code>DOMTokenList</code> objects are always
<span>case-sensitive</span>, even when the underlying string might
ordinarily be treated in a case-insensitive manner.</p>
<pre class="idl">interface <dfn>DOMTokenList</dfn> {
readonly attribute unsigned long <span title="dom-tokenlist-length">length</span>;
getter DOMString <span title="dom-tokenlist-item">item</span>(in unsigned long index);
boolean <span title="dom-tokenlist-contains">contains</span>(in DOMString token);
void <span title="dom-tokenlist-add">add</span>(in DOMString token);
void <span title="dom-tokenlist-remove">remove</span>(in DOMString token);
boolean <span title="dom-tokenlist-toggle">toggle</span>(in DOMString token);
<span title="dom-tokenlist-toString">stringifier</span> DOMString ();
};</pre>
<dl class="domintro">
<dt><var title="">tokenlist</var> . <code title="dom-tokenlist-length">length</code></dt>
<dd>
<p>Returns the number of tokens in the string.</p>
</dd>
<dt><var title="">element</var> = <var title="">tokenlist</var> . <code title="dom-tokenlist-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">tokenlist</var>[<var title="">index</var>]</dt>
<dd>
<p>Returns the token with index <var title="">index</var>. The tokens are returned in the order they are found in the underlying string.</p>
<p>Returns null if <var title="">index</var> is out of range.</p>
</dd>
<dt><var title="">hastoken</var> = <var title="">tokenlist</var> . <code title="dom-tokenlist-contains">contains</code>(<var title="">token</var>)</dt>
<dd>
<p>Returns true if the <var title="">token</var> is present; false otherwise.</p>
<p>Throws a <code>SYNTAX_ERR</code> exception if <var title="">token</var> is empty.</p>
<p>Throws an <code>INVALID_CHARACTER_ERR</code> exception if <var title="">token</var> contains any spaces.</p>
</dd>
<dt><var title="">tokenlist</var> . <code title="dom-tokenlist-add">add</code>(<var title="">token</var>)</dt>
<dd>
<p>Adds <var title="">token</var>, unless it is already present.</p>
<p>Throws a <code>SYNTAX_ERR</code> exception if <var title="">token</var> is empty.</p>
<p>Throws an <code>INVALID_CHARACTER_ERR</code> exception if <var title="">token</var> contains any spaces.</p>
</dd>
<dt><var title="">tokenlist</var> . <code title="dom-tokenlist-remove">remove</code>(<var title="">token</var>)</dt>
<dd>
<p>Removes <var title="">token</var> if it is present.</p>
<p>Throws a <code>SYNTAX_ERR</code> exception if <var title="">token</var> is empty.</p>
<p>Throws an <code>INVALID_CHARACTER_ERR</code> exception if <var title="">token</var> contains any spaces.</p>
</dd>
<dt><var title="">hastoken</var> = <var title="">tokenlist</var> . <code title="dom-tokenlist-toggle">toggle</code>(<var title="">token</var>)</dt>
<dd>
<p>Adds <var title="">token</var> if it is not present, or removes it if it is.</p>
<p>Throws a <code>SYNTAX_ERR</code> exception if <var title="">token</var> is empty.</p>
<p>Throws an <code>INVALID_CHARACTER_ERR</code> exception if <var title="">token</var> contains any spaces.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-tokenlist-length"><code>length</code></dfn>
attribute must return the number of tokens that result from <span
title="split a string on spaces">splitting the underlying string on
spaces</span>. This is the <var
title="dom-tokenlist-length">length</var>.</p>
<p>The object's <span>indices of the supported indexed
properties</span> are the numbers in the range zero to <span title=""><var
title="dom-tokenlist-length">length</var>-1</span>, unless the <var
title="dom-tokenlist-length">length</var> is zero, in which case
there are no <span>supported indexed properties</span>.</p>
<p>The <dfn title="dom-tokenlist-item"><code>item(<var
title="">index</var>)</code></dfn> method must <span title="split a
string on spaces">split the underlying string on spaces</span>,
preserving the order of the tokens as found in the underlying
string, and then return the <var title="">index</var>th item in this
list. If <var title="">index</var> is equal to or greater than the
number of tokens, then the method must return null.</p>
<p class="example">For example, if the string is "<code title="">a b
a c</code>" then there are four tokens: the token with index 0 is
"<code title="">a</code>", the token with index 1 is "<code
title="">b</code>", the token with index 2 is "<code
title="">a</code>", and the token with index 3 is "<code
title="">c</code>".</p>
<p>The <dfn title="dom-tokenlist-contains"><code>contains(<var
title="">token</var>)</code></dfn> method must run the following
algorithm:</p>
<ol>
<li>If the <var title="">token</var> argument is the empty string,
then raise a <code>SYNTAX_ERR</code> exception and stop the
algorithm.</li>
<li>If the <var title="">token</var> argument contains any <span
title="space character">space characters</span>, then raise an
<code>INVALID_CHARACTER_ERR</code> exception and stop the
algorithm.</li>
<li>Otherwise, <span title="split a string on spaces">split the
underlying string on spaces</span> to get the list of tokens in the
object's underlying string.</li>
<li>If the token indicated by <var title="">token</var> is a
<span>case-sensitive</span> match for one of the tokens in the
object's underlying string then return true and stop this
algorithm.</li>
<li>Otherwise, return false.</li>
</ol>
<p>The <dfn title="dom-tokenlist-add"><code>add(<var
title="">token</var>)</code></dfn> method must run the following
algorithm:</p>
<ol>
<li>If the <var title="">token</var> argument is the empty string,
then raise a <code>SYNTAX_ERR</code> exception and stop the
algorithm.</li>
<li>If the <var title="">token</var> argument contains any <span
title="space character">space characters</span>, then raise an
<code>INVALID_CHARACTER_ERR</code> exception and stop the
algorithm.</li>
<li>Otherwise, <span title="split a string on spaces">split the
underlying string on spaces</span> to get the list of tokens in the
object's underlying string.</li>
<li>If the given <var title="">token</var> is a
<span>case-sensitive</span> match for one of the tokens in the
<code>DOMTokenList</code> object's underlying string then stop the
algorithm.</li>
<li>Otherwise, if the <code>DOMTokenList</code> object's underlying
string is not the empty string and the last character of that
string is not a <span>space character</span>, then append a U+0020
SPACE character to the end of that string.</li>
<li>Append the value of <var title="">token</var> to the end of the
<code>DOMTokenList</code> object's underlying string.</li>
</ol>
<p>The <dfn title="dom-tokenlist-remove"><code>remove(<var
title="">token</var>)</code></dfn> method must run the following
algorithm:</p>
<ol>
<li>If the <var title="">token</var> argument is the empty string,
then raise a <code>SYNTAX_ERR</code> exception and stop the
algorithm.</li>
<li>If the <var title="">token</var> argument contains any <span
title="space character">space characters</span>, then raise an
<code>INVALID_CHARACTER_ERR</code> exception and stop the
algorithm.</li>
<li>Otherwise, <span title="remove a token from a string">remove
the given <var title="">token</var> from the underlying
string</span>.</li>
</ol>
<p>The <dfn title="dom-tokenlist-toggle"><code>toggle(<var
title="">token</var>)</code></dfn> method must run the following
algorithm:</p>
<ol>
<li>If the <var title="">token</var> argument is the empty string,
then raise a <code>SYNTAX_ERR</code> exception and stop the
algorithm.</li>
<li>If the <var title="">token</var> argument contains any <span
title="space character">space characters</span>, then raise an
<code>INVALID_CHARACTER_ERR</code> exception and stop the
algorithm.</li>
<li>Otherwise, <span title="split a string on spaces">split the
underlying string on spaces</span> to get the list of tokens in the
object's underlying string.</li>
<li>If the given <var title="">token</var> is a
<span>case-sensitive</span> match for one of the tokens in the
<code>DOMTokenList</code> object's underlying string then <span
title="remove a token from a string">remove the given <var
title="">token</var> from the underlying string</span> and stop the
algorithm, returning false.</li>
<li>Otherwise, if the <code>DOMTokenList</code> object's underlying
string is not the empty string and the last character of that
string is not a <span>space character</span>, then append a U+0020
SPACE character to the end of that string.</li>
<li>Append the value of <var title="">token</var> to the end of the
<code>DOMTokenList</code> object's underlying string.</li>
<li>Return true.</li>
</ol>
<p>Objects implementing the <code>DOMTokenList</code> interface must
<dfn title="dom-tokenlist-toString">stringify</dfn> to the object's
underlying string representation.</p>
</div>
<h4>DOMSettableTokenList</h4>
<p>The <code>DOMSettableTokenList</code> interface is the same as the
<code>DOMTokenList</code> interface, except that it allows the
underlying string to be directly changed.</p>
<pre class="idl">interface <dfn>DOMSettableTokenList</dfn> : <span>DOMTokenList</span> {
attribute DOMString <span title="dom-DOMSettableTokenList-value">value</span>;
};</pre>
<dl class="domintro">
<dt><var title="">tokenlist</var> . <code title="dom-DOMSettableTokenList-value">value</code></dt>
<dd>
<p>Returns the underlying string.</p>
<p>Can be set, to change the underlying string.</p>
</dd>
</dl>
<div class="impl">
<p>An object implementing the <code>DOMSettableTokenList</code>
interface must act as defined for the <code>DOMTokenList</code>
interface, except for the <code
title="dom-DOMSettableTokenList-value">value</code> attribute defined
here.</p>
<p>The <dfn
title="dom-DOMSettableTokenList-value"><code>value</code></dfn>
attribute must return the underlying string on getting, and must
replace the underlying string with the new value on setting.</p>
</div>
<div class="impl">
<h4>Safe passing of structured data</h4>
<p>When a user agent is required to obtain a <dfn>structured
clone</dfn> of an object, it must run the following algorithm, which
either returns a separate object, or throws an exception.</p>
<ol>
<li><p>Let <var title="">input</var> be the object being
cloned.</p></li>
<li><p>Let <var title="">memory</var> be a list of objects,
initially empty. (This is used to catch cycles.)</p></li>
<li><p>Let <var title="">output</var> be the object resulting from
calling the <span>internal structured cloning algorithm</span> with
<var title="">input</var> and <var title="">memory</var>.</p></li>
<li><p>Return <var title="">output</var>.</p></li>
</ol>
<p>The <dfn>internal structured cloning algorithm</dfn> is always
called with two arguments, <var title="">input</var> and <var
title="">memory</var>, and its behavior depends on the type of <var
title="">input</var>, as follows:</p>
<dl class="switch">
<dt>If <var title="">input</var> is the undefined value</dt>
<dd><p>Return the undefined value.</p></dd>
<dt>If <var title="">input</var> is the null value</dt>
<dd><p>Return the null value.</p></dd>
<dt>If <var title="">input</var> is the false value</dt>
<dd><p>Return the false value.</p></dd>
<dt>If <var title="">input</var> is the true value</dt>
<dd><p>Return the true value.</p></dd>
<dt>If <var title="">input</var> is a Number object</dt>
<dd><p>Return a newly constructed Number object with the same value as <var title="">input</var>.</p></dd>
<dt>If <var title="">input</var> is a String object</dt>
<dd><p>Return a newly constructed String object with the same value as <var title="">input</var>.</p></dd>
<dt>If <var title="">input</var> is a <code>Date</code> object</dt>
<dd><p>Return a newly constructed <code>Date</code> object with the same value as <var title="">input</var>.</p></dd>
<dt>If <var title="">input</var> is a <code>RegExp</code> object</dt>
<dd>
<p>Return a newly constructed <code>RegExp</code> object with the same pattern and flags as <var title="">input</var>.</p>
<p class="note">The value of the <code title="">lastIndex</code> property is not copied.</p>
</dd>
<dt>If <var title="">input</var> is a <code>ImageData</code> object</dt>
<dd><p>Return a newly constructed <code>ImageData</code> object
with the same <code title="dom-imagedata-width">width</code> and
<code title="dom-imagedata-height">height</code> as <var
title="">input</var>, and with a newly constructed
<code>CanvasPixelArray</code> for its <code
title="dom-imagedata-data">data</code> attribute, with the same
<code title="dom-canvaspixelarray-length">length</code> and pixel
values as the <var title="">input</var>'s.</p></dd>
<dt>If <var title="">input</var> is a <code>File</code> object</dt>
<dd><p>Return a newly constructed <code>File</code> object corresponding to the same underlying data.</p></dd>
<dt>If <var title="">input</var> is a <code>Blob</code> object</dt>
<dd><p>Return a newly constructed <code>Blob</code> object corresponding to the same underlying data.</p></dd>
<dt>If <var title="">input</var> is a <code>FileList</code> object</dt>
<dd><p>Return a newly constructed <code>FileList</code> object containing a list of newly constructed <code>File</code> objects corresponding to the same underlying data as those in <var title="">input</var>, maintaining their relative order.</p></dd>
<dt>If <var title="">input</var> is a host object (e.g. a DOM node)</dt>
<dd><p>Return the null value.</p></dd>
<dt>If <var title="">input</var> is an Array object</dt>
<dt>If <var title="">input</var> is an Object object</dt>
<dd>
<ol>
<li><p>If <var title="">input</var> is in <var
title="">memory</var>, then throw a
<code>NOT_SUPPORTED_ERR</code> exception and abort the overall
<span>structured clone</span> algorithm.</p></li>
<li><p>Otherwise, let <var title="">new memory</var> be a list
consisting of the items in <var title="">memory</var> with the
addition of <var title="">input</var>.</p></li>
<li><p>Create a new object, <var title="">output</var>, of the
same type as <var title="">input</var>: either an Array or an
Object.</p></li>
<li>
<p>For each enumerable property in <var title="">input</var>,
add a corresponding property to <var title="">output</var>
having the same name, and having a value created from invoking
the <span>internal structured cloning algorithm</span>
recursively with the value of the property as the "<var
title="">input</var>" argument and <var title="">new
memory</var> as the "<var title="">memory</var>" argument. The
order of the properties in the <var title="">input</var> and
<var title="">output</var> objects must be the same.</p>
<p class="note">This does not walk the prototype chain.</p>
</li>
<li><p>Return <var title="">output</var>.</p></li>
</ol>
</dd>
<dt>If <var title="">input</var> is another native object type (e.g. <code>Error</code>)</dt>
<dd><p>Return the null value.</p></dd>
</dl>
</div>
<h4>DOMStringMap</h4>
<p>The <code>DOMStringMap</code> interface represents a set of
name-value pairs. It exposes these using the scripting language's
native mechanisms for property access.</p>
<div class="impl">
<p>When a <code>DOMStringMap</code> object is instantiated, it is
associated with three algorithms, one for getting the list of
name-value pairs, one for setting names to certain values, and one
for deleting names.</p>
<pre class="idl">interface <dfn>DOMStringMap</dfn> {
getter DOMString (in DOMString name);
setter void (in DOMString name, in DOMString value);
creator void (in DOMString name, in DOMString value);
deleter void (in DOMString name);
};</pre>
<p>The <span>names of the supported named properties</span> on a
<code>DOMStringMap</code> object at any instant are the names of
each pair returned from the algorithm for getting the list of
name-value pairs at that instant.</p>
<p>When a <code>DOMStringMap</code> object is indexed to retrieve a
named property <var title="">name</var>, the value returned must be
the value component of the name-value pair whose name component is
<var title="">name</var> in the list returned by the algorithm for
getting the list of name-value pairs.</p>
<p>When a <code>DOMStringMap</code> object is indexed to create or
modify a named property <var title="">name</var> with value <var
title="">value</var>, the algorithm for setting names to certain
values must be run, passing <var title="">name</var> as the name and
the result of converting <var title="">value</var> to a
<code>DOMString</code> as the value.</p>
<p>When a <code>DOMStringMap</code> object is indexed to delete a
named property named <var title="">name</var>, the algorithm for
deleting names must be run, passing <var title="">name</var> as the
name.</p>
<p class="note">The <code>DOMStringMap</code> interface definition
here is only intended for JavaScript environments. Other language
bindings will need to define how <code>DOMStringMap</code> is to be
implemented for those languages.</p>
</div>
<div class="example">
<p>The <code title="dom-dataset">dataset</code> attribute on
elements exposes the <code title="attr-data-*">data-*</code>
attributes on the element.</p>
<p>Given the following fragment and elements with similar
constructions:</p>
<pre><img class="tower" id="tower5" data-x="12" data-y="5"
data-ai="robotarget" data-hp="46" data-ability="flames"
src="towers/rocket.png alt="Rocket Tower"></pre>
<p>...one could imagine a function <code
title="">splashDamage()</code> that takes some arguments, the first
of which is the element to process:</p>
<pre>function splashDamage(node, x, y, damage) {
if (node.classList.contains('tower') && // checking the 'class' attribute
node.dataset.x == x && // reading the 'data-x' attribute
node.dataset.y == y) { // reading the 'data-y' attribute
var hp = parseInt(node.dataset.hp); // reading the 'data-hp' attribute
hp = hp - damage;
if (hp < 0) {
hp = 0;
node.dataset.ai = 'dead'; // setting the 'data-ai' attribute
delete node.dataset.ability; // removing the 'data-ability' attribute
}
node.dataset.hp = hp; // setting the 'data-hp' attribute
}
}</pre>
</div>
<h4>DOM feature strings</h4>
<p>DOM3 Core defines mechanisms for checking for interface support,
and for obtaining implementations of interfaces, using <a
href="http://www.w3.org/TR/DOM-Level-3-Core/core.html#DOMFeatures">feature
strings</a>. <a href="#refsDOMCORE">[DOMCORE]</a></p>
<p>Authors are strongly discouraged from using these, as they are
notoriously unreliable and imprecise. Authors are encouraged to rely
on explicit feature testing or the graceful degradation behavior
intrinsic to some of the features in this specification.</p>
<div class="impl">
<p>For historical reasons, user agents should return the true value
when the <dfn title="hasFeature"><code>hasFeature(<var
title="">feature</var>, <var title="">version</var>)</code></dfn>
method of the <code>DOMImplementation</code> interface is invoked
with <var title="">feature</var> set to either "<code
title="">HTML</code>" or "<code title="">XHTML</code>" and <var
title="">version</var> set to either "<code>1.0</code>" or
"<code>2.0</code>".</p>
</div>
<h4>Exceptions</h4>
<p>The following are <code>DOMException</code> codes. <a
href="#refsDOMCORE">[DOMCORE]</a></p>
<ol class="brief">
<li value="1"><dfn><code>INDEX_SIZE_ERR</code></dfn></li>
<li value="2"><dfn><code>DOMSTRING_SIZE_ERR</code></dfn></li>
<li value="3"><dfn><code>HIERARCHY_REQUEST_ERR</code></dfn></li>
<li value="4"><dfn><code>WRONG_DOCUMENT_ERR</code></dfn></li>
<li value="5"><dfn><code>INVALID_CHARACTER_ERR</code></dfn></li>
<li value="6"><dfn><code>NO_DATA_ALLOWED_ERR</code></dfn></li>
<li value="7"><dfn><code>NO_MODIFICATION_ALLOWED_ERR</code></dfn></li>
<li value="8"><dfn><code>NOT_FOUND_ERR</code></dfn></li>
<li value="9"><dfn><code>NOT_SUPPORTED_ERR</code></dfn></li>
<li value="10"><dfn><code>INUSE_ATTRIBUTE_ERR</code></dfn></li>
<li value="11"><dfn><code>INVALID_STATE_ERR</code></dfn></li>
<li value="12"><dfn><code>SYNTAX_ERR</code></dfn></li>
<li value="13"><dfn><code>INVALID_MODIFICATION_ERR</code></dfn></li>
<li value="14"><dfn><code>NAMESPACE_ERR</code></dfn></li>
<li value="15"><dfn><code>INVALID_ACCESS_ERR</code></dfn></li>
<li value="16"><dfn><code>VALIDATION_ERR</code></dfn></li>
<li value="17"><dfn><code>TYPE_MISMATCH_ERR</code></dfn></li>
<li value="18"><dfn><code>SECURITY_ERR</code></dfn></li> <!-- actually in XHR for now -->
<li value="19"><dfn><code>NETWORK_ERR</code></dfn></li> <!-- actually in XHR for now -->
<li value="20"><dfn><code>ABORT_ERR</code></dfn></li> <!-- actually in XHR for now -->
<li value="21"><dfn><code>URL_MISMATCH_ERR</code></dfn></li> <!-- actually in workers for now -->
<li value="22"><dfn><code>QUOTA_EXCEEDED_ERR</code></dfn></li> <!-- actually defined right here for now -->
<!--v2DATAGRID <li value="23"><dfn><code>DATAGRID_MODEL_ERR</code></dfn></li> --> <!-- actually defined right here for now -->
<li value="81"><dfn><code>PARSE_ERR</code></dfn></li> <!-- actually defined in dom3ls -->
<li value="82"><dfn><code>SERIALIZE_ERR</code></dfn></li> <!-- actually defined in dom3ls -->
</ol>
<div class="impl">
<h4>Garbage collection</h4>
<p>There is an <dfn>implied strong reference</dfn> from any IDL
attribute that returns a pre-existing object to that object.</p>
<div class="example">
<p>For example, the <code>document.location</code> attribute means
that there is a strong reference from a <code>Document</code>
object to its <code>Location</code> object. Similarly, there is
always a strong reference from a <code>Document</code> to any
descendant nodes, and from any node to its owner
<code>Document</code>.</p>
</div>
</div>
<h2 id="dom">Semantics, structure, and APIs of HTML documents</h2>
<h3>Documents</h3>
<p>Every XML and HTML document in an HTML UA is represented by a
<code>Document</code> object. <a
href="#refsDOMCORE">[DOMCORE]</a></p>
<p><dfn>The document's address</dfn> is an <span>absolute URL</span>
that is set when the <code>Document</code> is created. <dfn>The
document's current address</dfn> is an <span>absolute URL</span>
that can change during the lifetime of the <code>Document</code>,
for example when the user <span title="navigate">navigates</span> to
a <span title="navigate-fragid">fragment identifier</span> on the
page. <span class="impl"><span>The document's current address</span>
must be set to <span>the document's address</span> when the
<code>Document</code> is created.</span></p>
<p class="note">Interactive user agents typically expose <span>the
document's current address</span> in their user interface.</p>
<p>When a <code>Document</code> is created by a <span
title="concept-script">script</span> using the <code
title="dom-DOMImplementation-createDocument">createDocument()</code>
or <code
title="dom-DOMHTMLImplementation-createHTMLDocument">createHTMLDocument()</code>
APIs, <span>the document's address</span> is the same as <span>the
document's address</span> of the <span>active document</span> of the
<span>script's browsing context</span>.</p>
<p><code>Document</code> objects are assumed to be <dfn>XML
documents</dfn> unless they are flagged as being <dfn>HTML
documents</dfn> when they are created. Whether a document is an
<span title="HTML documents">HTML document</span> or an <span
title="XML documents">XML document</span> affects the behavior of
certain APIs and the case-sensitivity of some selectors.</p>
<h4>Documents in the DOM</h4>
<p>All <code>Document</code> objects (in user agents implementing
this specification) <span class="impl">must</span> also implement
the <code>HTMLDocument</code> interface, available using
binding-specific methods. (This is the case whether or not the
document in question is an <span title="HTML documents">HTML
document</span> or indeed whether it contains any <span>HTML
elements</span> at all.) <code>Document</code> objects <span
class="impl">must</span> also implement the document-level interface
of any other namespaces that the UA supports.</p>
<p class="example">For example, if an HTML implementation also
supports SVG, then the <code>Document</code> object implements both
<code>HTMLDocument</code> and <code>SVGDocument</code>.</p>
<p class="note">Because the <code>HTMLDocument</code> interface is
now obtained using binding-specific casting methods instead of
simply being the primary interface of the document object, it is no
longer defined as inheriting from <code>Document</code>.</p>
<pre class="idl">[OverrideBuiltins]
interface <dfn>HTMLDocument</dfn> {
// <span>resource metadata management</span>
[PutForwards=href] readonly attribute <span>Location</span> <span title="dom-document-location">location</span>;
readonly attribute DOMString <span title="dom-document-URL">URL</span>;
attribute DOMString <span title="dom-document-domain">domain</span>;
readonly attribute DOMString <span title="dom-document-referrer">referrer</span>;
attribute DOMString <span title="dom-document-cookie">cookie</span>;
readonly attribute DOMString <span title="dom-document-lastModified">lastModified</span>;
readonly attribute DOMString <span title="dom-document-compatMode">compatMode</span>;
attribute DOMString <span title="dom-document-charset">charset</span>;
readonly attribute DOMString <span title="dom-document-characterSet">characterSet</span>;
readonly attribute DOMString <span title="dom-document-defaultCharset">defaultCharset</span>;
readonly attribute DOMString <span title="dom-document-readyState">readyState</span>;
// <span>DOM tree accessors</span>
attribute DOMString <span title="dom-document-title">title</span>;
attribute DOMString <span title="dom-document-dir">dir</span>;
attribute <span>HTMLElement</span> <span title="dom-document-body">body</span>;
readonly attribute <span>HTMLHeadElement</span> <span title="dom-document-head">head</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-document-images">images</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-document-embeds">embeds</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-document-plugins">plugins</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-document-links">links</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-document-forms">forms</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-document-scripts">scripts</span>;
NodeList <span title="dom-document-getElementsByName">getElementsByName</span>(in DOMString elementName);
NodeList <span title="dom-document-getElementsByClassName">getElementsByClassName</span>(in DOMString classNames);
NodeList <span title="dom-document-getItems">getItems</span>(in optional DOMString typeNames);
<span title="dom-document-namedItem">getter</span> any (in DOMString name);
// <span>dynamic markup insertion</span>
attribute DOMString <span title="dom-innerHTML">innerHTML</span>;
<span>HTMLDocument</span> <span title="dom-document-open">open</span>(in optional DOMString type, in optional DOMString replace);
<span>WindowProxy</span> <span title="dom-document-open">open</span>(in DOMString url, in DOMString name, in DOMString features, in optional boolean replace);
void <span title="dom-document-close">close</span>();
void <span title="dom-document-write">write</span>(in DOMString... text);
void <span title="dom-document-writeln">writeln</span>(in DOMString... text);
// <span>user interaction</span>
<span>Selection</span> <span title="dom-document-getSelection">getSelection</span>();
readonly attribute <span>Element</span> <span title="dom-document-activeElement">activeElement</span>;
boolean <span title="dom-document-hasFocus">hasFocus</span>();
attribute DOMString <span title="dom-document-designMode">designMode</span>;
boolean <span title="dom-document-execCommand">execCommand</span>(in DOMString commandId);
boolean <span title="dom-document-execCommand">execCommand</span>(in DOMString commandId, in boolean showUI);
boolean <span title="dom-document-execCommand">execCommand</span>(in DOMString commandId, in boolean showUI, in DOMString value);
boolean <span title="dom-document-queryCommandEnabled">queryCommandEnabled</span>(in DOMString commandId);
boolean <span title="dom-document-queryCommandIndeterm">queryCommandIndeterm</span>(in DOMString commandId);
boolean <span title="dom-document-queryCommandState">queryCommandState</span>(in DOMString commandId);
boolean <span title="dom-document-queryCommandSupported">queryCommandSupported</span>(in DOMString commandId);
DOMString <span title="dom-document-queryCommandValue">queryCommandValue</span>(in DOMString commandId);
readonly attribute <span>HTMLCollection</span> <span title="dom-document-commands">commands</span>;
// <span>event handler IDL attributes</span>
attribute <span>Function</span> <span title="handler-onabort">onabort</span>;
attribute <span>Function</span> <span title="handler-onblur">onblur</span>;
attribute <span>Function</span> <span title="handler-oncanplay">oncanplay</span>;
attribute <span>Function</span> <span title="handler-oncanplaythrough">oncanplaythrough</span>;
attribute <span>Function</span> <span title="handler-onchange">onchange</span>;
attribute <span>Function</span> <span title="handler-onclick">onclick</span>;
attribute <span>Function</span> <span title="handler-oncontextmenu">oncontextmenu</span>;
attribute <span>Function</span> <span title="handler-ondblclick">ondblclick</span>;
attribute <span>Function</span> <span title="handler-ondrag">ondrag</span>;
attribute <span>Function</span> <span title="handler-ondragend">ondragend</span>;
attribute <span>Function</span> <span title="handler-ondragenter">ondragenter</span>;
attribute <span>Function</span> <span title="handler-ondragleave">ondragleave</span>;
attribute <span>Function</span> <span title="handler-ondragover">ondragover</span>;
attribute <span>Function</span> <span title="handler-ondragstart">ondragstart</span>;
attribute <span>Function</span> <span title="handler-ondrop">ondrop</span>;
attribute <span>Function</span> <span title="handler-ondurationchange">ondurationchange</span>;
attribute <span>Function</span> <span title="handler-onemptied">onemptied</span>;
attribute <span>Function</span> <span title="handler-onended">onended</span>;
attribute <span>Function</span> <span title="handler-onerror">onerror</span>;
attribute <span>Function</span> <span title="handler-onfocus">onfocus</span>;
attribute <span>Function</span> <span title="handler-onformchange">onformchange</span>;
attribute <span>Function</span> <span title="handler-onforminput">onforminput</span>;
attribute <span>Function</span> <span title="handler-oninput">oninput</span>;
attribute <span>Function</span> <span title="handler-oninvalid">oninvalid</span>;
attribute <span>Function</span> <span title="handler-onkeydown">onkeydown</span>;
attribute <span>Function</span> <span title="handler-onkeypress">onkeypress</span>;
attribute <span>Function</span> <span title="handler-onkeyup">onkeyup</span>;
attribute <span>Function</span> <span title="handler-onload">onload</span>;
attribute <span>Function</span> <span title="handler-onloadeddata">onloadeddata</span>;
attribute <span>Function</span> <span title="handler-onloadedmetadata">onloadedmetadata</span>;
attribute <span>Function</span> <span title="handler-onloadstart">onloadstart</span>;
attribute <span>Function</span> <span title="handler-onmousedown">onmousedown</span>;
attribute <span>Function</span> <span title="handler-onmousemove">onmousemove</span>;
attribute <span>Function</span> <span title="handler-onmouseout">onmouseout</span>;
attribute <span>Function</span> <span title="handler-onmouseover">onmouseover</span>;
attribute <span>Function</span> <span title="handler-onmouseup">onmouseup</span>;
attribute <span>Function</span> <span title="handler-onmousewheel">onmousewheel</span>;
attribute <span>Function</span> <span title="handler-onpause">onpause</span>;
attribute <span>Function</span> <span title="handler-onplay">onplay</span>;
attribute <span>Function</span> <span title="handler-onplaying">onplaying</span>;
attribute <span>Function</span> <span title="handler-onprogress">onprogress</span>;
attribute <span>Function</span> <span title="handler-onratechange">onratechange</span>;
attribute <span>Function</span> <span title="handler-onreadystatechange">onreadystatechange</span>;
attribute <span>Function</span> <span title="handler-onscroll">onscroll</span>;
attribute <span>Function</span> <span title="handler-onseeked">onseeked</span>;
attribute <span>Function</span> <span title="handler-onseeking">onseeking</span>;
attribute <span>Function</span> <span title="handler-onselect">onselect</span>;
attribute <span>Function</span> <span title="handler-onshow">onshow</span>;
attribute <span>Function</span> <span title="handler-onstalled">onstalled</span>;
attribute <span>Function</span> <span title="handler-onsubmit">onsubmit</span>;
attribute <span>Function</span> <span title="handler-onsuspend">onsuspend</span>;
attribute <span>Function</span> <span title="handler-ontimeupdate">ontimeupdate</span>;
attribute <span>Function</span> <span title="handler-onvolumechange">onvolumechange</span>;
attribute <span>Function</span> <span title="handler-onwaiting">onwaiting</span>;
};
<span>Document</span> implements <span>HTMLDocument</span>;</pre>
<p>Since the <code>HTMLDocument</code> interface holds methods and
attributes related to a number of disparate features, the members of
this interface are described in various different sections.</p>
<h4>Security</h4>
<p>User agents <span class="impl">must</span> raise a
<code>SECURITY_ERR</code> exception whenever any of the members of
an <code>HTMLDocument</code> object are accessed by scripts whose
<span>effective script origin</span> is not the <span title="same
origin">same</span> as the <code>Document</code>'s <span>effective
script origin</span>.</p>
<h4><dfn>Resource metadata management</dfn></h4>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-URL">URL</code></dt>
<dd>
<p>Returns <span>the document's address</span>.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-referrer">referrer</code></dt>
<dd>
<p>Returns <span title="the document's current address">the
address</span> of the <code>Document</code> from which the user
navigated to this one, unless it was blocked or there was no such
document, in which case it returns the empty string.</p>
<p>The <code title="rel-noreferrer">noreferrer</code> link
type can be used to block the referrer.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-document-URL"><code>URL</code></dfn>
attribute must return <span>the document's address</span>.</p>
<p>The <dfn
title="dom-document-referrer"><code>referrer</code></dfn> attribute
must return either the <span title="the document's current
address">current address</span> of the <span>active document</span>
of the <span>source browsing context</span> <em>at the time the
navigation was started</em> (that is, the page which <span
title="navigate">navigated</span> the <span>browsing context</span>
to the current document), with any <span
title="url-fragment"><fragment></span> component removed; or
the empty string if there is no such originating page, or if the UA
has been configured not to report referrers in this case, or if the
navigation was initiated for a <span>hyperlink</span> with a <code
title="rel-noreferrer">noreferrer</code> keyword.</p>
<p class="note">In the case of HTTP, the <code
title="dom-document-referrer">referrer</code> IDL attribute will
match the <code title="http-referer">Referer</code> (sic) header
that was sent when <span title="fetch">fetching</span> the current
page.</p>
<p class="note">Typically user agents are configured to not report
referrers in the case where the referrer uses an encrypted protocol
and the current page does not (e.g. when navigating from an <code
title="">https:</code> page to an <code title="">http:</code>
page).</p>
<hr>
</div>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-cookie">cookie</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the HTTP cookies that apply to the
<code>Document</code>. If there are no cookies or cookies can't be
applied to this resource, the empty string will be returned.</p>
<p>Can be set, to add a new cookie to the element's set of HTTP
cookies.</p>
<p>If the <code>Document</code> has no <span>browsing
context</span> an <code>INVALID_STATE_ERR</code> exception will be
thrown. If the contents are <span title="sandboxed origin browsing
context flag">sandboxed into a unique origin</span>, a
<code>SECURITY_ERR</code> exception will be thrown.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-document-cookie"><code>cookie</code></dfn>
attribute represents the cookies of the resource.</p>
<p id="sandboxCookies">On getting, if the document is not associated
with a <span>browsing context</span> then the user agent must raise
an <code>INVALID_STATE_ERR</code> exception. Otherwise, if the
<span>sandboxed origin browsing context flag</span> was set on the
<span>browsing context</span> of the <code>Document</code> when the
<code>Document</code> was created, the user agent must raise a
<code>SECURITY_ERR</code> exception. Otherwise, if <span>the
document's address</span> does not use a server-based naming
authority, it must return the empty string. Otherwise, it must first
<span>obtain the storage mutex</span> and then return the
cookie-string for <span>the document's address</span> for a
"non-HTTP" API. <a href="#refsCOOKIES">[COOKIES]</a></p>
<p>On setting, if the document is not associated with a
<span>browsing context</span> then the user agent must raise an
<code>INVALID_STATE_ERR</code> exception. Otherwise, if the
<span>sandboxed origin browsing context flag</span> was set on the
<span>browsing context</span> of the <code>Document</code> when the
<code>Document</code> was created, the user agent must raise a
<code>SECURITY_ERR</code> exception. Otherwise, if <span>the
document's address</span> does not use a server-based naming
authority, it must do nothing. Otherwise, the user agent must
<span>obtain the storage mutex</span> and then act as it would when
<span title="receives a set-cookie-string">receiving a
set-cookie-string</span> for <span>the document's address</span> via
a "non-HTTP" API, consisting of the new value. <a
href="#refsCOOKIES">[COOKIES]</a></p>
<p class="note">Since the <code
title="dom-document-cookie">cookie</code> attribute is accessible
across frames, the path restrictions on cookies are only a tool to
help manage which cookies are sent to which parts of the site, and
are not in any way a security feature.</p>
<hr>
</div>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-lastmodified">lastModified</code></dt>
<dd>
<p>Returns the date of the last modification to the document, as
reported by the server, in the form "<code
title="">MM/DD/YYYY hh:mm:ss</code>".</p>
<p>If the last modification date is not known, the current time is
returned instead.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-document-lastModified"><code>lastModified</code></dfn>
attribute, on getting, must return the date and time of the
<code>Document</code>'s source file's last modification, in the
user's local time zone, in the following format:</p>
<ol>
<li> The month component of the date. </li>
<li> A U+002F SOLIDUS character (/). </li>
<li> The day component of the date. </li>
<li> A U+002F SOLIDUS character (/). </li>
<li> The year component of the date. </li>
<li> A U+0020 SPACE character. </li>
<li> The hours component of the time. </li>
<li> A U+003A COLON character (:). </li>
<li> The minutes component of the time. </li>
<li> A U+003A COLON character (:). </li>
<li> The seconds component of the time. </li>
</ol>
<p>All the numeric components above, other than the year, must be
given as two digits in the range U+0030 DIGIT ZERO (0) to U+0039
DIGIT NINE (9) representing the number in base ten, zero-padded if
necessary. The year must be given as the shortest possible string of
four or more digits in the range U+0030 DIGIT ZERO (0) to U+0039
DIGIT NINE (9) representing the number in base ten, zero-padded if
necessary.</p>
<p>The <code>Document</code>'s source file's last modification date
and time must be derived from relevant features of the networking
protocols used, e.g. from the value of the HTTP <code
title="http-last-modified">Last-Modified</code> header of the
document, or from metadata in the file system for local files. If
the last modification date and time are not known, the attribute
must return the current date and time in the above format.</p>
<hr>
</div>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-compatmode">compatMode</code></dt>
<dd>
<p>In a conforming document, returns the string "<code
title="">CSS1Compat</code>". (In <span>quirks mode</span>
documents, returns the string "<code title="">BackCompat</code>",
but a conforming document can never trigger <span>quirks
mode</span>.)</p>
</dd>
</dl>
<div class="impl">
<p>A <code>Document</code> is always set to one of three modes:
<dfn>no quirks mode</dfn>, the default; <dfn>quirks mode</dfn>, used
typically for legacy documents; and <dfn>limited quirks mode</dfn>,
also known as "almost standards" mode. The mode is only ever changed
from the default by the <span>HTML parser</span>, based on the
presence, absence, or value of the DOCTYPE string.</p>
<p>The <dfn
title="dom-document-compatMode"><code>compatMode</code></dfn> IDL
attribute must return the literal string "<code
title="">CSS1Compat</code>" unless the document has been set to
<span>quirks mode</span> by the <span>HTML parser</span>, in which
case it must instead return the literal string "<code
title="">BackCompat</code>".</p>
<hr>
</div>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-charset">charset</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the <span>document's character encoding</span>.</p>
<p>Can be set, to dynamically change the <span>document's
character encoding</span>.</p>
<p>New values that are not IANA-registered aliases supported by the user agent are ignored.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-characterSet">characterSet</code></dt>
<dd>
<p>Returns the <span>document's character encoding</span>.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-defaultCharset">defaultCharset</code></dt>
<dd>
<p>Returns what might be the user agent's default character encoding.</p>
</dd>
</dl>
<div class="impl">
<p>Documents have an associated <dfn title="document's character
encoding">character encoding</dfn>. When a <code>Document</code>
object is created, the <span>document's character encoding</span>
must be initialized to UTF-16. Various algorithms during page
loading affect this value, as does the <code
title="dom-document-charset">charset</code> setter. <a
href="#refsIANACHARSET">[IANACHARSET]</a></p>
<p>The <dfn title="dom-document-charset"><code>charset</code></dfn>
IDL attribute must, on getting, return the <span>preferred MIME
name</span> of the <span>document's character encoding</span>. On
setting, if the new value is an IANA-registered alias for a
character encoding supported by the user agent, the <span>document's
character encoding</span> must be set to that character
encoding. (Otherwise, nothing happens.)</p>
<p>The <dfn
title="dom-document-characterSet"><code>characterSet</code></dfn>
IDL attribute must, on getting, return the <span>preferred MIME
name</span> of the <span>document's character encoding</span>.</p>
<p>The <dfn
title="dom-document-defaultCharset"><code>defaultCharset</code></dfn>
IDL attribute must, on getting, return the <span>preferred MIME
name</span> of a character encoding, possibly the user's default
encoding, or an encoding associated with the user's current
geographical location, or any arbitrary encoding name.</p>
<hr>
</div>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-readyState">readyState</code></dt>
<dd>
<p>Returns "loading" while the <code>Document</code> is loading, and "complete" once it has loaded.</p>
<p>The <code title="event-readystatechange">readystatechange</code> event fires on the <code>Document</code> object when this value changes.</p>
</dd>
</dl>
<div class="impl">
<p>Each document has a <dfn>current document readiness</dfn>. When a
<code>Document</code> object is created, it must have its
<span>current document readiness</span> set to the string "loading"
if the document is associated with an <span>HTML parser</span> or an
<span>XML parser</span>, or to the string "complete"
otherwise. Various algorithms during page loading affect this
value. When the value is set, the user agent must <span>fire a
simple event</span> named <code
title="event-readystatechange">readystatechange</code> at the
<code>Document</code> object.</p>
<p>A <code>Document</code> is said to have an <dfn>active
parser</dfn> if it is associated with an <span>HTML parser</span> or
an <span>XML parser</span> that has not yet been <span title="stop
parsing">stopped</span> or aborted.</p>
<p>The <dfn
title="dom-document-readyState"><code>readyState</code></dfn> IDL
attribute must, on getting, return the <span>current document
readiness</span>.</p>
</div>
<h4><dfn>DOM tree accessors</dfn></h4>
<p><dfn>The <code>html</code> element</dfn> of a document is the
document's root element, if there is one and it's an
<code>html</code> element, or null otherwise.</p>
<hr>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-head">head</code></dt>
<dd>
<p>Returns <span>the <code>head</code> element</span>.</p>
</dd>
</dl>
<p><dfn>The <code>head</code> element</dfn> of a document is the
first <code>head</code> element that is a child of <span>the
<code>html</code> element</span>, if there is one, or null
otherwise.</p>
<div class="impl">
<p>The <dfn title="dom-document-head"><code>head</code></dfn>
attribute, on getting, must return <span>the <code>head</code>
element</span> of the document (a <code>head</code> element or
null).</p>
</div>
<hr>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-title">title</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the document's title, as given by <span>the
<code>title</code> element</span>.</p>
<p>Can be set, to update the document's title. If there is no
<span title="the head element"><code>head</code> element</span>,
the new value is ignored.</p>
<p>In SVG documents, the <code>SVGDocument</code> interface's
<code title="dom-svg-title">title</code> attribute takes
precedence.</p>
</dd>
</dl>
<p><dfn>The <code>title</code> element</dfn> of a document is the
first <code>title</code> element in the document (in tree order), if
there is one, or null otherwise.</p>
<div class="impl">
<p>The <dfn id="document.title"
title="dom-document-title"><code>title</code></dfn> attribute must,
on getting, run the following algorithm:</p>
<ol>
<li><p>If the <span>root element</span> is an <code>svg</code>
element in the "<code title="">http://www.w3.org/2000/svg</code>"
namespace, and the user agent supports SVG, then return the value
that would have been returned by the IDL attribute of the same name
on the <code>SVGDocument</code> interface. <a
href="#refsSVG">[SVG]</a></p></li>
<li><p>Otherwise, let <var title="">value</var> be a concatenation
of the data of all the child <span title="text node">text
nodes</span> of <span>the <code>title</code> element</span>, in
<span>tree order</span>, or the empty string if <span>the
<code>title</code> element</span> is null.</p></li>
<li><p>Replace any sequence of one or more consecutive <span
title="space character">space characters</span> in <var
title="">value</var> with a single U+0020 SPACE character.</p></li>
<li><p>Remove any leading or trailing <span title="space
character">space characters</span> in <var
title="">value</var>.</p></li>
<li><p>Return <var title="">value</var>.</p></li>
</ol>
<p>On setting, the following algorithm must be run. Mutation events
must be fired as appropriate.</p>
<ol>
<li><p>If the <span>root element</span> is an <code>svg</code>
element in the "<code title="">http://www.w3.org/2000/svg</code>"
namespace, and the user agent supports SVG, then the setter must
defer to the setter for the IDL attribute of the same name on the
<code>SVGDocument</code> interface (if it is readonly, then this
will raise an exception). Stop the algorithm here. <a
href="#refsSVG">[SVG]</a></p></li>
<li>If <span>the <code>title</code> element</span> is null and
<span>the <code>head</code> element</span> is null, then the
attribute must do nothing. Stop the algorithm here.</li>
<li>If <span>the <code>title</code> element</span> is null, then a
new <code>title</code> element must be created and appended to
<span>the <code>head</code> element</span>. Let <var
title="">element</var> be that element. Otherwise, let <var
title="">element</var> be <span>the <code>title</code>
element</span>.</li>
<li>The children of <var title="">element</var> (if any) must all
be removed.</li>
<li>A single <code>Text</code> node whose data is the new value
being assigned must be appended to <var
title="">element</var>.</li>
</ol>
<p>The <code title="dom-document-title">title</code> attribute on
the <code>HTMLDocument</code> interface should shadow the attribute
of the same name on the <code>SVGDocument</code> interface when the
user agent supports both HTML and SVG. <a
href="#refsSVG">[SVG]</a></p>
</div>
<hr>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-body">body</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns <span>the body element</span>.</p>
<p>Can be set, to replace <span>the body element</span>.</p>
<p>If the new value is not a <code>body</code> or <code>frameset</code> element, this will throw a <code>HIERARCHY_REQUEST_ERR</code> exception.</p>
</dd>
</dl>
<p><dfn>The body element</dfn> of a document is the first child of
<span>the <code>html</code> element</span> that is either a
<code>body</code> element or a <code>frameset</code> element. If
there is no such element, it is null. <span class="impl">If the body
element is null, then when the specification requires that events be
fired at "the body element", they must instead be fired at the
<code>Document</code> object.</span></p>
<div class="impl">
<p>The <dfn title="dom-document-body"><code>body</code></dfn>
attribute, on getting, must return <span>the body element</span> of
the document (either a <code>body</code> element, a
<code>frameset</code> element, or null). On setting, the following
algorithm must be run:</p>
<ol>
<!-- if changes are requested:
http://lxr.mozilla.org/seamonkey/source/content/html/document/src/nsHTMLDocument.cpp
search for ::GetBody ::SetBody
http://trac.webkit.org/projects/webkit/browser/trunk/WebCore/html/HTMLDocument.cpp
search for ::setBody
http://trac.webkit.org/projects/webkit/browser/trunk/WebCore/dom/Document.cpp
search for ::body
-->
<li>If the new value is not a <code>body</code> or
<code>frameset</code> element, then raise a
<code>HIERARCHY_REQUEST_ERR</code> exception and abort these
steps.</li>
<li>Otherwise, if the new value is the same as <span>the body
element</span>, do nothing. Abort these steps.</li>
<li>Otherwise, if <span>the body element</span> is not null, then
replace that element with the new value in the DOM, as if the root
element's <code title="">replaceChild()</code> method had been
called with the new value and <span title="the body element">the
incumbent body element</span> as its two arguments respectively,
then abort these steps.</li>
<li>Otherwise, <span>the body element</span> is null. Append
the new value to the root element.</li>
</ol>
</div>
<hr>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-images">images</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>img</code> elements in the <code>Document</code>.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-embeds">embeds</code></dt>
<dt><var title="">document</var> . <code title="dom-document-plugins">plugins</code></dt>
<dd>
<p>Return an <code>HTMLCollection</code> of the <code>embed</code> elements in the <code>Document</code>.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-links">links</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>a</code> and <code>area</code> elements in the <code>Document</code> that have <code title="attr-hyperlink-href">href</code> attributes.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-forms">forms</code></dt>
<dd>
<p>Return an <code>HTMLCollection</code> of the <code>form</code> elements in the <code>Document</code>.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-scripts">scripts</code></dt>
<dd>
<p>Return an <code>HTMLCollection</code> of the <code>script</code> elements in the <code>Document</code>.</p>
</dd>
</dl>
<div class="impl">
<!-- these all return the same object each time because of a rule in
the collection section -->
<p>The <dfn title="dom-document-images"><code>images</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only
<code>img</code> elements.</p>
<p>The <dfn title="dom-document-embeds"><code>embeds</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only
<code>embed</code> elements.</p>
<p>The <dfn title="dom-document-plugins"><code>plugins</code></dfn>
attribute must return the same object as that returned by the <code
title="dom-document-embeds">embeds</code> attribute.</p>
<p>The <dfn title="dom-document-links"><code>links</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only <code>a</code>
elements with <code title="attr-hyperlink-href">href</code>
attributes and <code>area</code> elements with <code
title="attr-hyperlink-href">href</code> attributes.</p>
<p>The <dfn title="dom-document-forms"><code>forms</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only
<code>form</code> elements.</p>
<p>The <dfn title="dom-document-scripts"><code>scripts</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only
<code>script</code> elements.</p>
<hr>
</div>
<dl class="domintro">
<dt><var title="">collection</var> = <var title="">document</var> . <code title="dom-document-getElementsByName">getElementsByName</code>(<var title="">name</var>)</dt>
<dd>
<p>Returns a <code>NodeList</code> of elements in the
<code>Document</code> that have a <code title="">name</code>
attribute with the value <var title="">name</var>.</p>
</dd>
<dt><var title="">collection</var> = <var title="">document</var> . <code title="dom-document-getElementsByClassName">getElementsByClassName(<var title="">classes</var>)</code></dt>
<dt><var title="">collection</var> = <var title="">element</var> . <code title="dom-getElementsByClassName">getElementsByClassName(<var title="">classes</var>)</code></dt>
<dd>
<p>Returns a <code>NodeList</code> of the elements in the object
on which the method was invoked (a <code>Document</code> or an
<code>Element</code>) that have all the classes given by <var
title="">classes</var>.</p>
<p>The <var title="">classes</var> argument is interpreted as a
space-separated list of classes.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-document-getElementsByName"><code>getElementsByName(<var
title="">name</var>)</code></dfn> method takes a string <var
title="">name</var>, and must return a live <code>NodeList</code>
containing all the <span>HTML elements</span> in that document that
have a <code title="">name</code> attribute whose value is equal to
the <var title="">name</var> argument (in a
<span>case-sensitive</span> manner), in <span>tree order</span>.</p>
<p>The <dfn
title="dom-document-getElementsByClassName"><code>getElementsByClassName(<var
title="">classNames</var>)</code></dfn> method takes a string that
contains a <span>set of space-separated tokens</span> representing
classes. When called, the method must return a live
<code>NodeList</code> object containing all the elements in the
document, in <span>tree order</span>, that have all the classes
specified in that argument, having obtained the classes by <span
title="split a string on spaces">splitting a string on
spaces</span>. (Duplicates are ignored.) If there are no tokens
specified in the argument, then the method must return an empty
<code>NodeList</code>. If the document is in <span>quirks
mode</span>, then the comparisons for the classes must be done in an
<span>ASCII case-insensitive</span> manner, otherwise, the
comparisons must be done in a <span>case-sensitive</span>
manner.</p>
<p>The <dfn
title="dom-getElementsByClassName"><code>getElementsByClassName(<var
title="">classNames</var>)</code></dfn> method on the
<code>HTMLElement</code> interface must return a live
<code>NodeList</code> with the nodes that the
<code>HTMLDocument</code> <code
title="dom-document-getElementsByClassName">getElementsByClassName()</code>
method would return when passed the same argument(s), excluding any
elements that are not descendants of the <code>HTMLElement</code>
object on which the method was invoked.</p>
</div>
<p>HTML, SVG, and MathML elements define which classes they are in
by having an attribute with no namespace with the name <code
title="">class</code> containing a space-separated list of classes
to which the element belongs. Other specifications may also allow
elements in their namespaces to be labeled as being in specific
classes.</p>
<div class="example">
<p>Given the following XHTML fragment:</p>
<pre><div id="example">
<p id="p1" class="aaa bbb"/>
<p id="p2" class="aaa ccc"/>
<p id="p3" class="bbb ccc"/>
</div></pre>
<p>A call to
<code>document.getElementById('example').getElementsByClassName('aaa')</code>
would return a <code>NodeList</code> with the two paragraphs
<code>p1</code> and <code>p2</code> in it.</p>
<p>A call to <code>getElementsByClassName('ccc bbb')</code>
would only return one node, however, namely <code>p3</code>. A call
to
<code>document.getElementById('example').getElementsByClassName('bbb ccc ')</code>
would return the same thing.</p>
<p>A call to <code>getElementsByClassName('aaa,bbb')</code> would
return no nodes; none of the elements above are in the "aaa,bbb"
class.</p>
</div>
<!-- v2:
> * xGetParentElementByClassName(rootElement, className, tagName) -
> Navigates upwards until we hit a parent element with the given class name and
> optional tag name.
-->
<div class="impl">
<hr>
<p>The <code>HTMLDocument</code> interface <span title="support
named properties">supports named properties</span>. The <span>names
of the supported named properties</span> at any moment consist of
the values of the <code title="attr-name">name</code> content
attributes of all the <code>applet</code>, <code>embed</code>,
<code>form</code>, <code>iframe</code>, <code>img</code>, and
<span>fallback-free</span> <code>object</code> elements in the
<code>Document</code> that have <code title="attr-name">name</code>
content attributes, and the values of the <code
title="attr-id">id</code> content attributes of all the
<code>applet</code> and <span>fallback-free</span>
<code>object</code> elements in the <code>Document</code> that have
<code title="attr-id">id</code> content attributes, and the values
of the <code title="attr-id">id</code> content attributes of all the
<code>img</code> elements in the <code>Document</code> that have
both <code title="attr-name">name</code> content attributes and
<code title="attr-id">id</code> content attributes.</p>
<p>When <dfn title="dom-document-namedItem">the
<code>HTMLDocument</code> object is indexed for property
retrieval</dfn> using a name <var title="">name</var>, then the user
agent must return the value obtained using the following steps:</p>
<ol>
<li>
<p>Let <var title="">elements</var> be the list of <span
title="dom-document-namedItem-filter">named elements</span> with
the name <var title="">name</var> in the <code>Document</code>.
<p class="note">There will be at least one such element, by
definition.<!-- (If there wasn't, then this algorithm wouldn't
have been invoked by Web IDL.) --></p>
</li>
<li>
<p>If <var title="">elements</var> has only one element, and that
element is an <code>iframe</code> element, then return the
<code>WindowProxy</code> object of the <span>nested browsing
context</span> represented by that <code>iframe</code> element,
and abort these steps.</p>
</li>
<li>
<p>Otherwise, if <var title="">elements</var> has only one
element, return that element and abort these steps.</p>
</li>
<li>
<p>Otherwise return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only <span
title="dom-document-namedItem-filter">named elements</span> with
the name <var title="">name</var>.</p> <!-- the same one each time
is returned, because of the rule under collections -->
</li>
<!--
Note that this named getter overrides built-in properties, as in:
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0D%0A...%3Ciframe%20name%3Dbody%3E%3C%2Fiframe%3E%3Cscript%3Ew(document.body)%3C%2Fscript%3E
This is what the "OverrideBuiltins" bit means in the IDL.
-->
</ol>
<p><dfn title="dom-document-nameditem-filter">Named elements</dfn>
with the name <var title="">name</var>, for the purposes of the
above algorithm, are those that are either:</p>
<ul>
<li><code>applet</code>, <code>embed</code>, <code>form</code>,
<code>iframe</code>, <code>img</code>, or
<span>fallback-free</span> <code>object</code> elements that have a
<code title="attr-name">name</code> content attribute whose value
is <var title="">name</var>, or</li>
<li><code>applet</code> or <span>fallback-free</span>
<code>object</code> elements that have an <code
title="attr-id">id</code> content attribute whose value is <var
title="">name</var>, or</li>
<li><code>img</code> elements that have an <code
title="attr-id">id</code> content attribute whose value is <var
title="">name</var>, and that have a <code
title="attr-name">name</code> content attribute present also.</li>
</ul>
<p>An <code>object</code> element is said to be
<dfn>fallback-free</dfn> if it has no <code>object</code> or
<code>embed</code> descendants.</p>
</div>
<hr>
<p class="note">The <code title="dom-document-dir">dir</code>
attribute on the <code>HTMLDocument</code> interface is defined
along with the <code title="attr-dir">dir</code> content
attribute.</p>
<h4>Creating documents</h4>
<p><span>XML documents</span> can be created from script using the
DOM <code
title="dom-DOMImplementation-createDocument">createDocument()</code>
method on the <code>DOMImplementation</code> interface.</p>
<p><span>HTML documents</span> can be created using the <code
title="dom-DOMHTMLImplementation-createHTMLDocument">createHTMLDocument()</code>
method:</p>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <dfn>DOMHTMLImplementation</dfn> {
<span>Document</span> <span title="dom-DOMHTMLImplementation-createHTMLDocument">createHTMLDocument</span>(in DOMString title);
};
<span>DOMImplementation</span> implements <span>DOMHTMLImplementation</span>;</pre>
<p>The <dfn
title="dom-DOMHTMLImplementation-createHTMLDocument"><code>createHTMLDocument(<var
title="">title</var>)</code></dfn> method, when invoked, must run the
following steps:</p>
<ol>
<li><p>Let <var title="">doc</var> be a newly created
<code>Document</code> object.</p></li>
<li><p>Mark <var title="">doc</var> as being an <span title="HTML
documents">HTML document</span>.</p></li>
<li><p>Create a <code>DocumentType</code> node with the <code
title="">name</code> attribute set to the string "<code
title="">html</code>", and the other attributes specific to
<code>DocumentType</code> objects set to the empty string, null,
and empty lists, as appropriate. Append the newly created node to
<var title="">doc</var>.</p></li>
<li><p>Create an <code>html</code> element, and append it to <var
title="">doc</var>.</p></li>
<li><p>Create a <code>head</code> element, and append it to the
<code>html</code> element created in the previous step.</p>
<li><p>Create a <code>title</code> element, and append it to the
<code>head</code> element created in the previous step.</p>
<li><p>Create a <code>Text</code> node, and set its <code
title="">data</code> attribute to the string given by the method's
argument (which could be the empty string). Append it to the
<code>title</code> element created in the previous step.</p>
<li><p>Create a <code>body</code> element, and append it to the
<code>html</code> element created in the earlier step.</p>
<li><p>Return <var title="">doc</var>.</p></li>
</ol>
<h3>Elements</h3>
<h4>Semantics</h4>
<p>Elements, attributes, and attribute values in HTML are defined
(by this specification) to have certain meanings (semantics). For
example, the <code>ol</code> element represents an ordered list, and
the <code title="attr-lang">lang</code> attribute represents the
language of the content.</p>
<p>Authors must not use elements, attributes, and attribute values
for purposes other than their appropriate intended semantic
purpose. Authors must not use elements, attributes, and attribute
values that are not permitted by this specification or <span>other
applicable specifications</span>.</p>
<div class="example">
<p>For example, the following document is non-conforming, despite
being syntactically correct:</p>
<pre class="bad"><!DOCTYPE HTML>
<html lang="en-GB">
<head> <title> Demonstration </title> </head>
<body>
<table>
<tr> <td> My favourite animal is the cat. </td> </tr>
<tr>
<td>
—<a href="http://example.org/~ernest/"><cite>Ernest</cite></a>,
in an essay from 1992
</td>
</tr>
</table>
</body>
</html></pre>
<p>...because the data placed in the cells is clearly not tabular
data (and the <code>cite</code> element mis-used). A corrected
version of this document might be:</p>
<pre><!DOCTYPE HTML>
<html lang="en-GB">
<head> <title> Demonstration </title> </head>
<body>
<blockquote>
<p> My favourite animal is the cat. </p>
</blockquote>
<p>
—<a href="http://example.org/~ernest/">Ernest</a>,
in an essay from 1992
</p>
</body>
</html></pre>
<p>This next document fragment, intended to represent the heading
of a corporate site, is similarly non-conforming because the second
line is not intended to be a heading of a subsection, but merely a
subheading or subtitle (a subordinate heading for the same
section).</p>
<pre class="bad"><body>
<h1>ABC Company</h1>
<h2>Leading the way in widget design since 1432</h2>
...</pre>
<p>The <code>hgroup</code> element is intended for these kinds of
situations:</p>
<pre><body>
<hgroup>
<h1>ABC Company</h1>
<h2>Leading the way in widget design since 1432</h2>
</hgroup>
...</pre>
<p>In the next example, there is a non-conforming attribute value
("carpet") and a non-conforming attribute ("texture"), which
is not permitted by this specification:</p>
<pre class="bad"><label>Carpet: <input type="carpet" name="c" texture="deep pile"></label></pre>
<p>Here would be an alternative and correct way to mark this up:</p>
<pre><label>Carpet: <input type="text" class="carpet" name="c" data-texture="deep pile"></label></pre>
</div>
<p>Through scripting and using other mechanisms, the values of
attributes, text, and indeed the entire structure of the document
may change dynamically while a user agent is processing it. The
semantics of a document at an instant in time are those represented
by the state of the document at that instant in time, and the
semantics of a document can therefore change over time. User agents
<span class="impl">must</span> update their presentation of the
document as this occurs.</p>
<p class="example">HTML has a <code>progress</code> element that
describes a progress bar. If its "value" attribute is dynamically
updated by a script, the UA would update the rendering to show the
progress changing.</p>
<h4>Elements in the DOM</h4>
<p>The nodes representing <span>HTML elements</span> in the DOM
<span class="impl">must</span> implement, and expose to scripts, the
interfaces listed for them in the relevant sections of this
specification. This includes <span>HTML elements</span> in <span>XML
documents</span>, even when those documents are in another context
(e.g. inside an XSLT transform).</p>
<p>Elements in the DOM <span title="represents">represent</span>
things; that is, they have intrinsic <em>meaning</em>, also known as
semantics.</p>
<p class="example">For example, an <code>ol</code> element
represents an ordered list.</p>
<p>The basic interface, from which all the <span>HTML
elements</span>' interfaces inherit, <span class="impl">and which
must be used by elements that have no additional
requirements,</span> is the <code>HTMLElement</code> interface.</p>
<pre class="idl">interface <dfn>HTMLElement</dfn> : <span>Element</span> {
// <span>DOM tree accessors</span>
NodeList <span title="dom-getElementsByClassName">getElementsByClassName</span>(in DOMString classNames);
// <span>dynamic markup insertion</span>
attribute DOMString <span title="dom-innerHTML">innerHTML</span>;
attribute DOMString <span title="dom-outerHTML">outerHTML</span>;
void <span title="dom-insertAdjacentHTML">insertAdjacentHTML</span>(in DOMString position, in DOMString text);
// <span>metadata attributes</span>
attribute DOMString <span title="dom-id">id</span>;
attribute DOMString <span title="dom-title">title</span>;
attribute DOMString <span title="dom-lang">lang</span>;
attribute DOMString <span title="dom-dir">dir</span>;
attribute <span>DOMString</span> <span title="dom-className">className</span>;
readonly attribute <span>DOMTokenList</span> <span title="dom-classList">classList</span>;
readonly attribute <span>DOMStringMap</span> <span title="dom-dataset">dataset</span>;
// <span>microdata</span>
attribute boolean <span title="dom-itemScope">itemScope</span>;
attribute DOMString <span title="dom-itemType">itemType</span>;
attribute DOMString <span title="dom-itemId">itemId</span>;
attribute DOMString <span title="dom-itemRef">itemRef</span>;
[PutForwards=<span title="dom-DOMSettableTokenList-value">value</span>] readonly attribute <span>DOMSettableTokenList</span> <span title="dom-itemProp">itemProp</span>;
readonly attribute <span>HTMLPropertiesCollection</span> <span title="dom-properties">properties</span>;
attribute any <span title="dom-itemValue">itemValue</span>;
// <span>user interaction</span>
attribute boolean <span title="dom-hidden">hidden</span>;
void <span title="dom-click">click</span>();
void <span title="dom-scrollIntoView">scrollIntoView</span>();
void <span title="dom-scrollIntoView">scrollIntoView</span>(in boolean top);
attribute long <span title="dom-tabindex">tabIndex</span>;
void <span title="dom-focus">focus</span>();
void <span title="dom-blur">blur</span>();
attribute DOMString <span title="dom-accessKey">accessKey</span>;
readonly attribute DOMString <span title="dom-accessKeyLabel">accessKeyLabel</span>;
attribute boolean <span title="dom-draggable">draggable</span>;
attribute DOMString <span title="dom-contentEditable">contentEditable</span>;
readonly attribute boolean <span title="dom-isContentEditable">isContentEditable</span>;
attribute <span>HTMLMenuElement</span> <span title="dom-contextMenu">contextMenu</span>;
attribute DOMString <span title="dom-spellcheck">spellcheck</span>;
// <span>command API</span>
readonly attribute DOMString <span title="dom-command-ro-commandType">commandType</span>;
readonly attribute DOMString <span title="dom-command-ro-label">label</span>;
readonly attribute DOMString <span title="dom-command-ro-icon">icon</span>;
readonly attribute boolean <span title="dom-command-ro-disabled">disabled</span>;
readonly attribute boolean <span title="dom-command-ro-checked">checked</span>;<!-- v2COMMAND
readonly attribute <span>HTMLCollection</span> <span title="dom-command-ro-triggers">triggers</span>;-->
// <span>styling</span>
readonly attribute <span>CSSStyleDeclaration</span> <span title="dom-style">style</span>;
// <span>event handler IDL attributes</span>
attribute <span>Function</span> <span title="handler-onabort">onabort</span>;
attribute <span>Function</span> <span title="handler-onblur">onblur</span>;
attribute <span>Function</span> <span title="handler-oncanplay">oncanplay</span>;
attribute <span>Function</span> <span title="handler-oncanplaythrough">oncanplaythrough</span>;
attribute <span>Function</span> <span title="handler-onchange">onchange</span>;
attribute <span>Function</span> <span title="handler-onclick">onclick</span>;
attribute <span>Function</span> <span title="handler-oncontextmenu">oncontextmenu</span>;
attribute <span>Function</span> <span title="handler-ondblclick">ondblclick</span>;
attribute <span>Function</span> <span title="handler-ondrag">ondrag</span>;
attribute <span>Function</span> <span title="handler-ondragend">ondragend</span>;
attribute <span>Function</span> <span title="handler-ondragenter">ondragenter</span>;
attribute <span>Function</span> <span title="handler-ondragleave">ondragleave</span>;
attribute <span>Function</span> <span title="handler-ondragover">ondragover</span>;
attribute <span>Function</span> <span title="handler-ondragstart">ondragstart</span>;
attribute <span>Function</span> <span title="handler-ondrop">ondrop</span>;
attribute <span>Function</span> <span title="handler-ondurationchange">ondurationchange</span>;
attribute <span>Function</span> <span title="handler-onemptied">onemptied</span>;
attribute <span>Function</span> <span title="handler-onended">onended</span>;
attribute <span>Function</span> <span title="handler-onerror">onerror</span>;
attribute <span>Function</span> <span title="handler-onfocus">onfocus</span>;
attribute <span>Function</span> <span title="handler-onformchange">onformchange</span>;
attribute <span>Function</span> <span title="handler-onforminput">onforminput</span>;
attribute <span>Function</span> <span title="handler-oninput">oninput</span>;
attribute <span>Function</span> <span title="handler-oninvalid">oninvalid</span>;
attribute <span>Function</span> <span title="handler-onkeydown">onkeydown</span>;
attribute <span>Function</span> <span title="handler-onkeypress">onkeypress</span>;
attribute <span>Function</span> <span title="handler-onkeyup">onkeyup</span>;
attribute <span>Function</span> <span title="handler-onload">onload</span>;
attribute <span>Function</span> <span title="handler-onloadeddata">onloadeddata</span>;
attribute <span>Function</span> <span title="handler-onloadedmetadata">onloadedmetadata</span>;
attribute <span>Function</span> <span title="handler-onloadstart">onloadstart</span>;
attribute <span>Function</span> <span title="handler-onmousedown">onmousedown</span>;
attribute <span>Function</span> <span title="handler-onmousemove">onmousemove</span>;
attribute <span>Function</span> <span title="handler-onmouseout">onmouseout</span>;
attribute <span>Function</span> <span title="handler-onmouseover">onmouseover</span>;
attribute <span>Function</span> <span title="handler-onmouseup">onmouseup</span>;
attribute <span>Function</span> <span title="handler-onmousewheel">onmousewheel</span>;
attribute <span>Function</span> <span title="handler-onpause">onpause</span>;
attribute <span>Function</span> <span title="handler-onplay">onplay</span>;
attribute <span>Function</span> <span title="handler-onplaying">onplaying</span>;
attribute <span>Function</span> <span title="handler-onprogress">onprogress</span>;
attribute <span>Function</span> <span title="handler-onratechange">onratechange</span>;
attribute <span>Function</span> <span title="handler-onreadystatechange">onreadystatechange</span>;
attribute <span>Function</span> <span title="handler-onscroll">onscroll</span>;
attribute <span>Function</span> <span title="handler-onseeked">onseeked</span>;
attribute <span>Function</span> <span title="handler-onseeking">onseeking</span>;
attribute <span>Function</span> <span title="handler-onselect">onselect</span>;
attribute <span>Function</span> <span title="handler-onshow">onshow</span>;
attribute <span>Function</span> <span title="handler-onstalled">onstalled</span>;
attribute <span>Function</span> <span title="handler-onsubmit">onsubmit</span>;
attribute <span>Function</span> <span title="handler-onsuspend">onsuspend</span>;
attribute <span>Function</span> <span title="handler-ontimeupdate">ontimeupdate</span>;
attribute <span>Function</span> <span title="handler-onvolumechange">onvolumechange</span>;
attribute <span>Function</span> <span title="handler-onwaiting">onwaiting</span>;
};
interface <dfn>HTMLUnknownElement</dfn> : <span>HTMLElement</span> { };</pre>
<p>The <code>HTMLElement</code> interface holds methods and
attributes related to a number of disparate features, and the
members of this interface are therefore described in various
different sections of this specification.</p>
<div class="impl">
<p>The <code>HTMLUnknownElement</code> interface must be used for
<span>HTML elements</span> that are not defined by this
specification (or <span>other applicable specifications</span>).</p>
</div>
<h4><dfn>Global attributes</dfn></h4>
<p>The following attributes are common to and may be specified on
all <span>HTML elements</span><span class="impl"> (even those not
defined in this specification)</span>:</p>
<ul class="brief">
<li><code title="attr-accesskey">accesskey</code></li>
<li><code title="attr-class">class</code></li>
<li><code title="attr-contenteditable">contenteditable</code></li>
<li><code title="attr-contextmenu">contextmenu</code></li>
<li><code title="attr-dir">dir</code></li>
<li><code title="attr-draggable">draggable</code></li>
<li><code title="attr-hidden">hidden</code></li>
<li><code title="attr-id">id</code></li>
<li><code title="attr-itemid">itemid</code></li>
<li><code title="attr-itemprop">itemprop</code></li>
<li><code title="attr-itemref">itemref</code></li>
<li><code title="attr-itemscope">itemscope</code></li>
<li><code title="attr-itemtype">itemtype</code></li>
<li><code title="attr-lang">lang</code></li>
<li><code title="attr-spellcheck">spellcheck</code></li>
<li><code title="attr-style">style</code></li>
<li><code title="attr-tabindex">tabindex</code></li>
<li><code title="attr-title">title</code></li>
</ul>
<hr>
<p>The following <span>event handler content attributes</span> may
be specified on any <span title="HTML elements">HTML
element</span>:</p>
<ul class="brief">
<li><code title="handler-onabort">onabort</code></li>
<li><code title="handler-onblur">onblur</code>*</li>
<li><code title="handler-oncanplay">oncanplay</code></li>
<li><code title="handler-oncanplaythrough">oncanplaythrough</code></li>
<li><code title="handler-onchange">onchange</code></li>
<li><code title="handler-onclick">onclick</code></li>
<li><code title="handler-oncontextmenu">oncontextmenu</code></li>
<li><code title="handler-ondblclick">ondblclick</code></li>
<li><code title="handler-ondrag">ondrag</code></li>
<li><code title="handler-ondragend">ondragend</code></li>
<li><code title="handler-ondragenter">ondragenter</code></li>
<li><code title="handler-ondragleave">ondragleave</code></li>
<li><code title="handler-ondragover">ondragover</code></li>
<li><code title="handler-ondragstart">ondragstart</code></li>
<li><code title="handler-ondrop">ondrop</code></li>
<li><code title="handler-ondurationchange">ondurationchange</code></li>
<li><code title="handler-onemptied">onemptied</code></li>
<li><code title="handler-onended">onended</code></li>
<li><code title="handler-onerror">onerror</code>*</li>
<li><code title="handler-onfocus">onfocus</code>*</li>
<li><code title="handler-onformchange">onformchange</code></li>
<li><code title="handler-onforminput">onforminput</code></li>
<li><code title="handler-oninput">oninput</code></li>
<li><code title="handler-oninvalid">oninvalid</code></li>
<li><code title="handler-onkeydown">onkeydown</code></li>
<li><code title="handler-onkeypress">onkeypress</code></li>
<li><code title="handler-onkeyup">onkeyup</code></li>
<li><code title="handler-onload">onload</code>*</li>
<li><code title="handler-onloadeddata">onloadeddata</code></li>
<li><code title="handler-onloadedmetadata">onloadedmetadata</code></li>
<li><code title="handler-onloadstart">onloadstart</code></li>
<li><code title="handler-onmousedown">onmousedown</code></li>
<li><code title="handler-onmousemove">onmousemove</code></li>
<li><code title="handler-onmouseout">onmouseout</code></li>
<li><code title="handler-onmouseover">onmouseover</code></li>
<li><code title="handler-onmouseup">onmouseup</code></li>
<li><code title="handler-onmousewheel">onmousewheel</code></li>
<li><code title="handler-onpause">onpause</code></li>
<li><code title="handler-onplay">onplay</code></li>
<li><code title="handler-onplaying">onplaying</code></li>
<li><code title="handler-onprogress">onprogress</code></li>
<li><code title="handler-onratechange">onratechange</code></li>
<li><code title="handler-onreadystatechange">onreadystatechange</code></li>
<li><code title="handler-onscroll">onscroll</code></li>
<li><code title="handler-onseeked">onseeked</code></li>
<li><code title="handler-onseeking">onseeking</code></li>
<li><code title="handler-onselect">onselect</code></li>
<li><code title="handler-onshow">onshow</code></li>
<li><code title="handler-onstalled">onstalled</code></li>
<li><code title="handler-onsubmit">onsubmit</code></li>
<li><code title="handler-onsuspend">onsuspend</code></li>
<li><code title="handler-ontimeupdate">ontimeupdate</code></li>
<li><code title="handler-onvolumechange">onvolumechange</code></li>
<li><code title="handler-onwaiting">onwaiting</code></li>
</ul>
<p class="note">The attributes marked with an asterisk have a
different meaning when specified on <code>body</code> elements as
those elements expose <span>event handlers</span> of the
<code>Window</code> object with the same names.</p>
<p class="note">While these attributes apply to all elements, they
are not useful on all elements. For example, only <span title="media
element">media elements</span> will ever receive a <code
title="event-media-volumechange">volumechange</code> event fired by
the user agent.</p>
<hr>
<p><span title="custom data attribute">Custom data attributes</span>
(e.g. <code title="">data-foldername</code> or <code
title="">data-msgid</code>) can be specified on any <span
title="HTML elements">HTML element</span>, to store custom data
specific to the page.</p>
<hr>
<p>In <span>HTML documents</span>, elements in the <span>HTML
namespace</span> may have an <code title="">xmlns</code> attribute
specified, if, and only if, it has the exact value
"<code>http://www.w3.org/1999/xhtml</code>". This does not apply to
<span>XML documents</span>.</p>
<p class="note">In HTML, the <code title="">xmlns</code> attribute
has absolutely no effect. It is basically a talisman. It is allowed
merely to make migration to and from XHTML mildly easier. When
parsed by an <span>HTML parser</span>, the attribute ends up in no
namespace, not the "<code>http://www.w3.org/2000/xmlns/</code>"
namespace like namespace declaration attributes in XML do.</p>
<p class="note">In XML, an <code title="">xmlns</code> attribute is
part of the namespace declaration mechanism, and an element cannot
actually have an <code title="">xmlns</code> attribute in no
namespace specified.</p>
<hr>
<p>To enable assistive technology products to expose a more
fine-grained interface than is otherwise possible with HTML elements
and attributes, a set of <span>annotations for assistive technology
products</span> can be specified.</p>
<h5>The <dfn title="attr-id"><code>id</code></dfn> attribute</h5>
<p>The <code title="attr-id">id</code> attribute specifies its
element's <dfn title="concept-id">unique identifier (ID)</dfn>. The
value must be unique amongst all the IDs in the element's <span>home
subtree</span> and must contain at least one character. The value
must not contain any <span title="space character">space
characters</span>.</p>
<!-- space characters are disallowed because space-separated lists
of IDs otherwise would not be able to reach all valid IDs -->
<p class="note">An element's <span title="concept-id">unique
identifier</span> can be used for a variety of purposes, most
notably as a way to link to specific parts of a document using
fragment identifiers, as a way to target an element when scripting,
and as a way to style a specific element from CSS.</p>
<div class="impl">
<p>If the value is not the empty string, user agents must associate
the element with the given value (exactly, including any space
characters) for the purposes of ID matching within the element's
<span>home subtree</span> (e.g. for selectors in CSS or for the
<code>getElementById()</code> method in the DOM).</p>
<p>Identifiers are opaque strings. Particular meanings should not be
derived from the value of the <code title="attr-id">id</code>
attribute.</p>
<p>This specification doesn't preclude an element having multiple
IDs, if other mechanisms (e.g. DOM Core methods) can set an
element's ID in a way that doesn't conflict with the <code
title="attr-id">id</code> attribute.</p>
<p>The <dfn title="dom-id"><code>id</code></dfn> IDL attribute must
<span>reflect</span> the <code title="attr-id">id</code> content
attribute.</p>
</div>
<h5>The <dfn title="attr-title"><code>title</code></dfn> attribute</h5>
<p>The <code title="attr-title">title</code> attribute
<span>represents</span> advisory information for the element, such
as would be appropriate for a tooltip. On a link, this could be the
title or a description of the target resource; on an image, it could
be the image credit or a description of the image; on a paragraph,
it could be a footnote or commentary on the text; on a citation, it
could be further information about the source; and so forth. The
value is text.</p>
<p>If this attribute is omitted from an element, then it implies
that the <code title="attr-title">title</code> attribute of the
nearest ancestor <span title="HTML elements">HTML element</span>
with a <code title="attr-title">title</code> attribute set is also
relevant to this element. Setting the attribute overrides this,
explicitly stating that the advisory information of any ancestors is
not relevant to this element. Setting the attribute to the empty
string indicates that the element has no advisory information.</p>
<p>If the <code title="attr-title">title</code> attribute's value
contains U+000A LINE FEED (LF) characters, the content is split into
multiple lines. Each U+000A LINE FEED (LF) character represents a
line break.</p>
<div class="example">
<p>Caution is advised with respect to the use of newlines in <code
title="attr-title">title</code> attributes.</p>
<p>For instance, the following snippet actually defines an
abbreviation's expansion <em>with a line break in it</em>:</p>
<pre class="bad"><p>My logs show that there was some interest in <abbr title="Hypertext
Transport Protocol">HTTP</abbr> today.</p></pre>
</div>
<p>Some elements, such as <code>link</code>, <code>abbr</code>, and
<code>input</code>, define additional semantics for the <code
title="attr-title">title</code> attribute beyond the semantics
described above.</p>
<div class="impl">
<hr>
<p>The <dfn title="dom-title"><code>title</code></dfn> IDL attribute
must <span>reflect</span> the <code title="attr-title">title</code>
content attribute.</p>
</div>
<h5>The <code title="attr-lang">lang</code> and <code
title="attr-xml-lang">xml:lang</code> attributes</h5>
<p>The <dfn title="attr-lang"><code>lang</code></dfn> attribute (in
no namespace) specifies the primary <dfn>language</dfn> for the
element's contents and for any of the element's attributes that
contain text. Its value must be a valid BCP 47 language code, or
the empty string. <a href="#refsBCP47">[BCP47]</a></p>
<p>The <dfn title="attr-xml-lang"><code title="">lang</code></dfn>
attribute in the <span>XML namespace</span> is defined in XML. <a
href="#refsXML">[XML]</a></p>
<p>If these attributes are omitted from an element, then the
language of this element is the same as the language of its parent
element, if any. Setting the attribute to the empty string indicates
that the primary language is unknown.</p> <!-- UA conformance
requires for this are below -->
<p>The <code title="attr-lang">lang</code> attribute in no namespace
may be used on any <span title="HTML elements">HTML
element</span>.</p>
<p>The <span title="attr-xml-lang"><code title="">lang</code>
attribute in the <span>XML namespace</span></span> may be used on
<span>HTML elements</span> in <span>XML documents</span>, as well as
elements in other namespaces if the relevant specifications allow it
(in particular, MathML and SVG allow <span
title="attr-xml-lang"><code title="">lang</code> attributes in the
<span>XML namespace</span></span> to be specified on their
elements). If both the <code title="attr-lang">lang</code> attribute
in no namespace and the <span title="attr-xml-lang"><code
title="">lang</code> attribute in the <span>XML
namespace</span></span> are specified on the same element, they must
have exactly the same value when compared in an <span>ASCII
case-insensitive</span> manner.</p>
<p>Authors must not use the <span title="attr-xml-lang"><code
title="">lang</code> attribute in the <span>XML
namespace</span></span> on <span>HTML elements</span> in <span>HTML
documents</span>. To ease migration to and from XHTML, authors may
specify an attribute in no namespace with no prefix and with the
literal localname "<code title="">xml:lang</code>" on <span>HTML
elements</span> in <span>HTML documents</span>, but such attributes
must only be specified if a <code title="attr-lang">lang</code>
attribute in no namespace is also specified, and both attributes
must have the same value when compared in an <span>ASCII
case-insensitive</span> manner.</p>
<p class="note">The attribute in no namespace with no prefix and
with the literal localname "<code title="">xml:lang</code>" has no
effect on language processing.</p>
<div class="impl">
<hr>
<p>To determine the language of a node, user agents must look at the
nearest ancestor element (including the element itself if the node
is an element) that has a <span title="attr-xml-lang"><code
title="">lang</code> attribute in the <span>XML
namespace</span></span> set or is an <span title="HTML
elements">HTML element</span> and has a <code
title="attr-lang">lang</code> in no namespace attribute set. That
attribute specifies the language of the node.</p>
<p>If both the <code title="attr-lang">lang</code> attribute in no
namespace and the <span title="attr-xml-lang"><code
title="">lang</code> attribute in the <span>XML
namespace</span></span> are set on an element, user agents must use
the <span title="attr-xml-lang"><code title="">lang</code> attribute
in the <span>XML namespace</span></span>, and the <code
title="attr-lang">lang</code> attribute in no namespace must be
<span title="ignore">ignored</span> for the purposes of determining
the element's language.</p>
<p>If no explicit language is given for any ancestors of the node,
including the <span>root element</span>, but there is a
<span>document-wide default language</span> set, then that is the
language of the node.</p>
<p>If there is no <span>document-wide default language</span>, then
language information from a higher-level protocol (such as HTTP), if
any, must be used as the final fallback language. In the absence of
any language information, and in cases where the higher-level
protocol reports multiple languages, the language of the node is
unknown (the empty string).</p>
<p>If the resulting value is not a recognized language code, then it
must be treated as an unknown language (as if the value was the
empty string).</p>
<hr>
<p>User agents may use the element's language to determine proper
processing or rendering (e.g. in the selection of appropriate
fonts or pronunciations, or for dictionary selection). <!--User
agents must not use the element's language to determine text
directionality. (commented out because text directionality is a
rendering-level concern.)--></p>
<hr>
<p>The <dfn title="dom-lang"><code>lang</code></dfn> IDL attribute
must <span>reflect</span> the <code title="attr-lang">lang</code>
content attribute in no namespace.</p>
</div>
<h5>The <dfn title="attr-xml-base"><code>xml:base</code></dfn>
attribute (XML only)</h5>
<p>The <code title="attr-xml-base">xml:base</code> attribute is
defined in XML Base. <a href="#refsXMLBASE">[XMLBASE]</a></p>
<p>The <code title="attr-xml-base">xml:base</code> attribute may be
used on elements of <span>XML documents</span>. Authors must not
use the <code title="attr-xml-base">xml:base</code> attribute in
<span>HTML documents</span>.</p>
<h5>The <dfn title="attr-dir"><code>dir</code></dfn> attribute</h5>
<p>The <code title="attr-dir">dir</code> attribute specifies the
element's text directionality. The attribute is an <span>enumerated
attribute</span> with the keyword <code title="">ltr</code> mapping
to the state <i>ltr</i>, and the keyword <code title="">rtl</code>
mapping to the state <i>rtl</i>. The attribute has no
defaults.</p>
<div class="impl">
<p>The processing of this attribute is primarily performed by the
presentation layer. For example, the rendering section in this
specification defines a mapping from this attribute to the CSS
'direction' and 'unicode-bidi' properties, and CSS defines rendering
in terms of those properties.</p>
</div>
<p><dfn>The directionality</dfn> of an element, which is used in
particular by the <code>canvas</code> element's text rendering API,
is either 'ltr' or 'rtl'. If the user agent supports CSS and the
'direction' property on this element has a computed value of either
'ltr' or 'rtl', then that is <span>the directionality</span> of the
element. Otherwise, if the element is <span>being rendered</span>,
then <span>the directionality</span> of the element is the
directionality used by the presentation layer, potentially
determined from the value of the <code title="attr-dir">dir</code>
attribute on the element. Otherwise, if the element's <code
title="attr-dir">dir</code> attribute has the state <i>ltr</i>, the
element's directionality is 'ltr' (left-to-right); if the attribute
has the state <i>rtl</i>, the element's directionality is 'rtl'
(right-to-left); and otherwise, the element's directionality is the
same as its parent element, or 'ltr' if there is no parent
element.</p>
<hr>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-dir">dir</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns <span>the <code>html</code> element</span>'s <code title="attr-dir">dir</code> attribute's value, if any.</p>
<p>Can be set, to either "<code title="">ltr</code>" or "<code title="">rtl</code>", to replace <span>the <code>html</code> element</span>'s <code title="attr-dir">dir</code> attribute's value.</p>
<p>If there is no <span title="the html element"><code>html</code> element</span>, returns the empty string and ignores new values.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-dir"><code>dir</code></dfn> IDL attribute on
an element must <span>reflect</span> the <code
title="attr-dir">dir</code> content attribute of that element,
<span>limited to only known values</span>.</p>
<p>The <dfn title="dom-document-dir"><code>dir</code></dfn> IDL
attribute on <code>HTMLDocument</code> objects must
<span>reflect</span> the <code title="attr-dir">dir</code> content
attribute of <span>the <code>html</code> element</span>, if any,
<span>limited to only known values</span>. If there is no such
element, then the attribute must return the empty string and do
nothing on setting.</p>
</div>
<p class="note">Authors are strongly encouraged to use the <code
title="attr-dir">dir</code> attribute to indicate text direction
rather than using CSS, since that way their documents will continue
to render correctly even in the absence of CSS (e.g. as interpreted
by search engines).</p>
<h5 id="classes">The <dfn title="attr-class"><code>class</code></dfn> attribute</h5>
<p>Every <span title="HTML elements">HTML element</span> may have a
<code title="attr-class">class</code> attribute specified.</p>
<p>The attribute, if specified, must have a value that is a
<span>set of space-separated tokens</span> representing the various
classes that the element belongs to.</p>
<div class="impl">
<p>The classes that an <span title="HTML elements">HTML
element</span> has assigned to it consists of all the classes
returned when the value of the <code title="attr-class">class</code>
attribute is <span title="split a string on spaces">split on
spaces</span>. (Duplicates are ignored.)</p>
</div>
<p class="note">Assigning classes to an element affects class
matching in selectors in CSS, the <code
title="dom-document-getElementsByClassName">getElementsByClassName()</code>
method in the DOM, and other such features.</p>
<p>There are no additional restrictions on the tokens authors can
use in the <code title="attr-class">class</code> attribute, but
authors are encouraged to use values that describe the nature of the
content, rather than values that describe the desired presentation
of the content.</p>
<div class="impl">
<hr>
<p>The <dfn title="dom-className"><code>className</code></dfn> and
<dfn title="dom-classList"><code>classList</code></dfn> IDL
attributes must both <span>reflect</span> the <code
title="attr-class">class</code> content attribute.</p>
</div>
<h5>The <dfn title="attr-style"><code>style</code></dfn> attribute</h5>
<p>All <span>HTML elements</span> may have the <code
title="attr-style">style</code> content attribute set. If specified,
the attribute must contain only a list of zero or more
semicolon-separated (;) CSS declarations. <a
href="#refsCSS">[CSS]</a></p>
<div class="impl">
<p>In user agents that support CSS, the attribute's value must be
parsed when the attribute is added or has its value changed, with
its value treated as the body (the part inside the curly brackets)
of a declaration block in a rule whose selector matches just the
element on which the attribute is set. All <span
title="URL">URLs</span> in the value must be <span title="resolve a
url">resolved</span> relative to the element when the attribute is
parsed.<!-- so dynamic changes to the base URL don't affect the CSS
--> For the purposes of the CSS cascade, the attribute must be
considered to be a 'style' attribute at the author level.</p>
</div>
<p>Documents that use <code title="attr-style">style</code>
attributes on any of their elements must still be comprehensible and
usable if those attributes were removed.</p>
<p class="note">In particular, using the <code
title="attr-style">style</code> attribute to hide and show content,
or to convey meaning that is otherwise not included in the document,
is non-conforming. (To hide and show content, use the <code
title="attr-hidden">hidden</code> attribute.)</p>
<hr>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-style">style</code></dt>
<dd>
<p>Returns a <code>CSSStyleDeclaration</code> object for the element's <code title="attr-style">style</code> attribute.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-style"><code>style</code></dfn> IDL attribute
must return a <code>CSSStyleDeclaration</code> whose value
represents the declarations specified in the attribute, if
present. Mutating the <code>CSSStyleDeclaration</code> object must
create a <code title="attr-font-style">style</code> attribute on the
element (if there isn't one already) and then change its value to be
a value representing the serialized form of the
<code>CSSStyleDeclaration</code> object. <a
href="#refsCSSOM">[CSSOM]</a>
</div>
<div class="example">
<p>In the following example, the words that refer to colors are
marked up using the <code>span</code> element and the <code
title="attr-style">style</code> attribute to make those words show
up in the relevant colors in visual media.</p>
<pre><p>My sweat suit is <span style="color: green; background:
transparent">green</span> and my eyes are <span style="color: blue;
background: transparent">blue</span>.</p></pre>
</div>
<h5><dfn>Embedding custom non-visible data</dfn></h5>
<p>A <dfn>custom data attribute</dfn> is an attribute in no
namespace whose name starts with the string "<dfn
title="attr-data-*"><code>data-</code></dfn>", has at least one
character after the hyphen, is <span>XML-compatible</span>, and
contains no characters in the range U+0041 to U+005A (LATIN CAPITAL
LETTER A to LATIN CAPITAL LETTER Z).</p>
<p class="note">All attributes on <span>HTML elements</span> in
<span>HTML documents</span> get ASCII-lowercased automatically, so
the restriction on ASCII uppercase letters doesn't affect such
documents.</p>
<p><span title="custom data attribute">Custom data attributes</span>
are intended to store custom data private to the page or
application, for which there are no more appropriate attributes or
elements.</p>
<p>These attributes are not intended for use by software that is
independent of the site that uses the attributes.</p>
<div class="example">
<p>For instance, a site about music could annotate list items
representing tracks in an album with custom data attributes
containing the length of each track. This information could then be
used by the site itself to allow the user to sort the list by track
length, or to filter the list for tracks of certain lengths.</p>
<pre><ol>
<li data-length="2m11s">Beyond The Sea</li>
...
</ol></pre>
<p>It would be inappropriate, however, for the user to use generic
software not associated with that music site to search for tracks
of a certain length by looking at this data.</p>
<p>This is because these attributes are intended for use by the
site's own scripts, and are not a generic extension mechanism for
publicly-usable metadata.</p>
</div>
<p>Every <span title="HTML elements">HTML element</span> may have
any number of <span title="custom data attribute">custom data
attributes</span> specified, with any value.</p>
<hr>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-dataset">dataset</code></dt>
<dd>
<p>Returns a <code>DOMStringMap</code> object for the element's <code title="attr-data-*">data-*</code> attributes.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-dataset"><code>dataset</code></dfn> IDL
attribute provides convenient accessors for all the <code
title="attr-data-*">data-*</code> attributes on an element. On
getting, the <code title="dom-dataset">dataset</code> IDL attribute
must return a <code>DOMStringMap</code> object, associated with the
following algorithms, which expose these attributes on their
element:</p>
<dl>
<dt>The algorithm for getting the list of name-value pairs</dt>
<dd>
<ol>
<li>Let <var title="">list</var> be an empty list of name-value
pairs.</li>
<li>For each content attribute on the element whose first five
characters are the string "<code title="">data-</code>", add a
name-value pair to <var title="">list</var> whose name is the
attribute's name with the first five character removed and whose
value is the attribute's value.</li>
<li>Return <var title="">list</var>.</li>
</ol>
</dd>
<dt>The algorithm for setting names to certain values</dt>
<dd>
<ol>
<li>Let <var title="">name</var> be the concatenation of the
string <code title="">data-</code> and the name passed to the
algorithm.</li>
<li>Let <var title="">value</var> be the value passed to the
algorithm.</li>
<li>Set the value of the attribute with the name <var
title="">name</var>, to the value <var title="">value</var>,
replacing any previous value if the attribute already existed. If
<code title="">setAttribute()</code> would have raised an
exception when setting an attribute with the name <var
title="">name</var>, then this must raise the same
exception.</li>
</ol>
</dd>
<dt>The algorithm for deleting names</dt>
<dd>
<ol>
<li>Let <var title="">name</var> be the concatenation of the
string <code title="">data-</code> and the name passed to the
algorithm.</li>
<li>Remove the attribute with the name <var title="">name</var>,
if such an attribute exists. Do nothing otherwise.</li>
</ol>
</dd>
</dl>
</div>
<div class="example">
<p>If a Web page wanted an element to represent a space ship,
e.g. as part of a game, it would have to use the <code
class="attr-class">class</code> attribute along with <code
title="attr-data-*">data-*</code> attributes:</p>
<pre><div class="spaceship" data-id="92432"
data-weapons="laser 2" data-shields="50%"
data-x="30" data-y="10" data-z="90">
<button class="fire"
onclick="spaceships[this.parentNode.dataset.id].fire()">
Fire
</button>
</div></pre>
</div>
<p>Authors should carefully design such extensions so that when the
attributes are ignored and any associated CSS dropped, the page is
still usable.</p>
<div class="impl">
<p>User agents must not derive any implementation behavior from
these attributes or values. Specifications intended for user agents
must not define these attributes to have any meaningful values.</p>
</div>
<h4>Element definitions</h4>
<p>Each element in this specification has a definition that includes
the following information:</p>
<dl>
<dt>Categories</dt>
<dd>A list of <span title="content categories">categories</span> to
which the element belongs. These are used when defining the
<span>content models</span> for each element.</dd>
<dt>Contexts in which this element may be used</dt>
<dd>A <em>non-normative</em> description of where the element can
be used. This information is redundant with the content models of
elements that allow this one as a child, and is provided only as a
convenience.</dd>
<dt>Content model</dt>
<dd>A normative description of what content must be included as
children and descendants of the element.</dd>
<dt>Content attributes</dt>
<dd>A normative list of attributes that may be specified on the
element.</dd>
<dt>DOM interface</dt>
<dd>A normative definition of a DOM interface that such elements
must implement.</dd>
</dl>
<p>This is then followed by a description of what the element
<span>represents</span>, along with any additional normative
conformance criteria that may apply to authors<span title=""
class="impl"> and implementations</span>. Examples are sometimes
also included.</p>
<h4><dfn>Content models</dfn></h4>
<p>Each element defined in this specification has a content model: a
description of the element's expected contents. An <span title="HTML
elements">HTML element</span> must have contents that match the
requirements described in the element's content model.</p>
<p class="note">As noted in the conformance and terminology
sections, for the purposes of determining if an element matches its
content model or not, <span title="text
node"><code>CDATASection</code> nodes in the DOM are treated as
equivalent to <code>Text</code> nodes</span>, and <a
href="#entity-references">entity reference nodes are treated as if
they were expanded in place</a>.</p>
<p>The <span title="space character">space characters</span> are
always allowed between elements. User agents represent these
characters between elements in the source markup as text nodes in
the DOM.<!-- not a conf criteria since the parser now requires this
--> Empty <span title="text node">text nodes</span> and <span
title="text node">text nodes</span> consisting of just sequences of
those characters are considered <dfn>inter-element
whitespace</dfn>.</p>
<p><span>Inter-element whitespace</span>, comment nodes, and
processing instruction nodes must be ignored when establishing
whether an element's contents match the element's content model or
not, and must be ignored when following algorithms that define
document and element semantics.</p>
<p>An element <var title="">A</var> is said to be <dfn>preceded or
followed</dfn> by a second element <var title="">B</var> if <var
title="">A</var> and <var title="">B</var> have the same parent node
and there are no other element nodes or text nodes (other than
<span>inter-element whitespace</span>) between them.</p>
<p>Authors must not use <span>HTML elements</span> anywhere except
where they are explicitly allowed, as defined for each element, or
as explicitly required by other specifications. For XML compound
documents, these contexts could be inside elements from other
namespaces, if those elements are defined as providing the relevant
contexts.</p>
<div class="example">
<p>The Atom specification defines the Atom <code
title="">content</code> element, when its <code
title="">type</code> attribute has the value <code
title="">xhtml</code>, as requiring that it contains a single HTML
<code>div</code> element. Thus, a <code>div</code> element is
allowed in that context, even though this is not explicitly
normatively stated by this specification. <a
href="#refsATOM">[ATOM]</a></p>
</div>
<p>In addition, <span>HTML elements</span> may be orphan nodes
(i.e. without a parent node).</p>
<div class="example">
<p>For example, creating a <code>td</code> element and storing it
in a global variable in a script is conforming, even though
<code>td</code> elements are otherwise only supposed to be used
inside <code>tr</code> elements.</p>
<pre>var data = {
name: "Banana",
cell: document.createElement('td'),
};</pre>
</div>
<h5>Kinds of content</h5>
<p>Each element in HTML falls into zero or more <dfn title="content
categories">categories</dfn> that group elements with similar
characteristics together. The following broad categories are used in
this specification:</p>
<ul class="brief">
<li><span>Metadata content</span></li>
<li><span>Flow content</span></li>
<li><span>Sectioning content</span></li>
<li><span>Heading content</span></li>
<li><span>Phrasing content</span></li>
<li><span>Embedded content</span></li>
<li><span>Interactive content</span></li>
</ul>
<p class="note">Some elements also fall into other categories, which
are defined in other parts of this specification.</p>
<p>These categories are related as follows:</p>
<p><object width="512" height="288"
data="images/content-venn.svg"><img src="images/content-venn.png"
alt="Sectioning content, heading content, phrasing content, and
embedded content are all types of flow content. Embedded content is
also a type of phrasing content."></object></p>
<p>In addition, certain elements are categorized as <span
title="form-associated element">form-associated elements</span> and
further subcategorized to define their role in various form-related
processing models.</p>
<p>Some elements have unique requirements and do not fit into any
particular category.</p>
<h6>Metadata content</h6>
<p><dfn>Metadata content</dfn> is content that sets up the
presentation or behavior of the rest of the content, or that sets
up the relationship of the document with other documents, or that
conveys other "out of band" information.</p>
<ul class="brief category-list">
<li><code>base</code></li>
<li><code>command</code></li>
<li><code>link</code></li>
<li><code>meta</code></li>
<li><code>noscript</code></li>
<li><code>script</code></li>
<li><code>style</code></li>
<li><code>title</code></li>
</ul>
<p>Elements from other namespaces whose semantics are primarily
metadata-related (e.g. RDF) are also <span>metadata
content</span>.</p>
<div class="example">
<p>Thus, in the XML serialization, one can use RDF, like this:</p>
<pre><html xmlns="http://www.w3.org/1999/xhtml"
xmlns:r="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<head>
<title>Hedral's Home Page</title>
<r:RDF>
<Person xmlns="http://www.w3.org/2000/10/swap/pim/contact#"
r:about="http://hedral.example.com/#">
<fullName>Cat Hedral</fullName>
<mailbox r:resource="mailto:hedral@damowmow.com"/>
<personalTitle>Sir</personalTitle>
</Person>
</r:RDF>
</head>
<body>
<h1>My home page</h1>
<p>I like playing with string, I guess. Sister says squirrels are fun
too so sometimes I follow her to play with them.</p>
</body>
</html></pre>
<p>This isn't possible in the HTML serialization, however.</p>
</div>
<h6>Flow content</h6>
<p>Most elements that are used in the body of documents and
applications are categorized as <dfn>flow content</dfn>.</p>
<ul class="brief category-list">
<li><code>a</code></li>
<li><code>abbr</code></li>
<li><code>address</code></li>
<li><code>area</code> (if it is a descendant of a <code>map</code> element)</li>
<li><code>article</code></li>
<li><code>aside</code></li>
<li><code>audio</code></li>
<li><code>b</code></li>
<li><code>bdo</code></li>
<li><code>blockquote</code></li>
<li><code>br</code></li>
<li><code>button</code></li>
<li><code>canvas</code></li>
<li><code>cite</code></li>
<li><code>code</code></li>
<li><code>command</code></li>
<!-- v2DATAGRID <li><code>datagrid</code></li> -->
<li><code>datalist</code></li>
<li><code>del</code></li>
<li><code>details</code></li>
<li><code>dfn</code></li>
<li><code>div</code></li>
<li><code>dl</code></li>
<li><code>em</code></li>
<li><code>embed</code></li>
<li><code>fieldset</code></li>
<li><code>figure</code></li>
<li><code>footer</code></li>
<li><code>form</code></li>
<li><code>h1</code></li>
<li><code>h2</code></li>
<li><code>h3</code></li>
<li><code>h4</code></li>
<li><code>h5</code></li>
<li><code>h6</code></li>
<li><code>header</code></li>
<li><code>hgroup</code></li>
<li><code>hr</code></li>
<li><code>i</code></li>
<li><code>iframe</code></li>
<li><code>img</code></li>
<li><code>input</code></li>
<li><code>ins</code></li>
<li><code>kbd</code></li>
<li><code>keygen</code></li>
<li><code>label</code></li>
<li><code>link</code> (if the <code title="attr-itemprop">itemprop</code> attribute is present)</li>
<li><code>map</code></li>
<li><code>mark</code></li>
<li><code>math</code></li>
<li><code>menu</code></li>
<li><code>meta</code> (if the <code title="attr-itemprop">itemprop</code> attribute is present)</li>
<li><code>meter</code></li>
<li><code>nav</code></li>
<li><code>noscript</code></li>
<li><code>object</code></li>
<li><code>ol</code></li>
<li><code>output</code></li>
<li><code>p</code></li>
<li><code>pre</code></li>
<li><code>progress</code></li>
<li><code>q</code></li>
<li><code>ruby</code></li>
<li><code>samp</code></li>
<li><code>script</code></li>
<li><code>section</code></li>
<li><code>select</code></li>
<li><code>small</code></li>
<li><code>span</code></li>
<li><code>strong</code></li>
<li><code>style</code> (if the <code title="attr-style-scoped">scoped</code> attribute is present)</li>
<li><code>sub</code></li>
<li><code>sup</code></li>
<li><code>svg</code></li>
<li><code>table</code></li>
<li><code>textarea</code></li>
<li><code>time</code></li>
<li><code>ul</code></li>
<li><code>var</code></li>
<li><code>video</code></li>
<li><span title="text content">Text</span></li>
</ul>
<p>As a general rule, elements whose content model allows any
<span>flow content</span> should have either at least one descendant
<span>text node</span> that is not <span>inter-element
whitespace</span>, or at least one descendant element node that is
<span>embedded content</span>. For the purposes of this requirement,
<code>del</code> elements and their descendants must not be counted
as contributing to the ancestors of the <code>del</code>
element.</p>
<p>This requirement is not a hard requirement, however, as there are
many cases where an element can be empty legitimately, for example
when it is used as a placeholder which will later be filled in by a
script, or when the element is part of a template and would on most
pages be filled in but on some pages is not relevant.</p>
<h6>Sectioning content</h6>
<p><dfn>Sectioning content</dfn> is content that defines the scope
of <span title="heading content">headings</span> and <span
title="footer">footers</span>.</p>
<ul class="brief category-list">
<li><code>article</code></li>
<li><code>aside</code></li>
<li><code>nav</code></li>
<li><code>section</code></li>
</ul>
<p>Each <span>sectioning content</span> element potentially has a
heading and an <span>outline</span>. See the section on
<span>headings and sections</span> for further details.</p>
<p class="note">There are also certain elements that are <span
title="sectioning root">sectioning roots</span>. These are distinct
from <span>sectioning content</span>, but they can also have an
<span>outline</span>.</p>
<h6>Heading content</h6>
<p><dfn>Heading content</dfn> defines the header of a section
(whether explicitly marked up using <span>sectioning content</span>
elements, or implied by the heading content itself).</p>
<ul class="brief category-list">
<li><code>h1</code></li>
<li><code>h2</code></li>
<li><code>h3</code></li>
<li><code>h4</code></li>
<li><code>h5</code></li>
<li><code>h6</code></li>
<li><code>hgroup</code></li>
</ul>
<h6>Phrasing content</h6>
<p><dfn>Phrasing content</dfn> is the text of the document, as well
as elements that mark up that text at the intra-paragraph
level. Runs of <span>phrasing content</span> form <span
title="paragraph">paragraphs</span>.</p>
<ul class="brief category-list">
<li><code>a</code> (if it contains only <span>phrasing content</span>)</li>
<li><code>abbr</code></li>
<li><code>area</code> (if it is a descendant of a <code>map</code> element)</li>
<li><code>audio</code></li>
<li><code>b</code></li>
<li><code>bdo</code></li>
<li><code>br</code></li>
<li><code>button</code></li>
<li><code>canvas</code></li>
<li><code>cite</code></li>
<li><code>code</code></li>
<li><code>command</code></li>
<li><code>datalist</code></li>
<li><code>del</code> (if it contains only <span>phrasing content</span>)</li>
<li><code>dfn</code></li>
<li><code>em</code></li>
<li><code>embed</code></li>
<li><code>i</code></li>
<li><code>iframe</code></li>
<li><code>img</code></li>
<li><code>input</code></li>
<li><code>ins</code> (if it contains only <span>phrasing content</span>)</li>
<li><code>kbd</code></li>
<li><code>keygen</code></li>
<li><code>label</code></li>
<li><code>link</code> (if the <code title="attr-itemprop">itemprop</code> attribute is present)</li>
<li><code>map</code> (if it contains only <span>phrasing content</span>)</li>
<li><code>mark</code></li>
<li><code>math</code></li>
<li><code>meta</code> (if the <code title="attr-itemprop">itemprop</code> attribute is present)</li>
<li><code>meter</code></li>
<li><code>noscript</code></li>
<li><code>object</code></li>
<li><code>output</code></li>
<li><code>progress</code></li>
<li><code>q</code></li>
<li><code>ruby</code></li>
<li><code>samp</code></li>
<li><code>script</code></li>
<li><code>select</code></li>
<li><code>small</code></li>
<li><code>span</code></li>
<li><code>strong</code></li>
<li><code>sub</code></li>
<li><code>sup</code></li>
<li><code>svg</code></li>
<li><code>textarea</code></li>
<li><code>time</code></li>
<li><code>var</code></li>
<li><code>video</code></li>
<li><span title="text content">Text</span></li>
</ul>
<p>As a general rule, elements whose content model allows any
<span>phrasing content</span> should have either at least one
descendant <span>text node</span> that is not <span>inter-element
whitespace</span>, or at least one descendant element node that is
<span>embedded content</span>. For the purposes of this requirement,
nodes that are descendants of <code>del</code> elements must not be
counted as contributing to the ancestors of the <code>del</code>
element.</p>
<p class="note">Most elements that are categorized as phrasing
content can only contain elements that are themselves categorized as
phrasing content, not any flow content.</p>
<p><dfn title="text content">Text</dfn>, in the context of content
models, means <span title="text node">text nodes</span>. <span
title="text content">Text</span> is sometimes used as a content
model on its own, but is also <span>phrasing content</span>, and can
be <span>inter-element whitespace</span> (if the <span title="text
node">text nodes</span> are empty or contain just <span title="space
character">space characters</span>).</p>
<h6>Embedded content</h6>
<p><dfn>Embedded content</dfn> is content that imports another
resource into the document, or content from another vocabulary that
is inserted into the document.</p>
<ul class="brief category-list">
<li><code>audio</code></li>
<li><code>canvas</code></li>
<li><code>embed</code></li>
<li><code>iframe</code></li>
<li><code>img</code></li>
<li><code>math</code></li>
<li><code>object</code></li>
<li><code>svg</code></li>
<li><code>video</code></li>
</ul>
<p>Elements that are from namespaces other than the <span>HTML
namespace</span> and that convey content but not metadata, are
<span>embedded content</span> for the purposes of the content models
defined in this specification. (For example, MathML, or SVG.)</p>
<p>Some embedded content elements can have <dfn>fallback
content</dfn>: content that is to be used when the external resource
cannot be used (e.g. because it is of an unsupported format). The
element definitions state what the fallback is, if any.</p>
<h6>Interactive content</h6>
<!--
TESTS:
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E%0A%3Cp%20tabindex%3D1%3Etest%20%3Ca%20href%3D%22%22%3E%20%3Cem%3Etest%3C/em%3E%20%3C/a%3E%0A%3Cscript%3E%0A%20function%20test%20%28e%29%20%7B%20w%28e.type%20+%20%27%20on%20%27%20+%20e.target.tagName%20+%20%27%20through%20%27%20+%20e.currentTarget.tagName%29%3B%20%7D%0A%20document.getElementsByTagName%28%27a%27%29%5B0%5D.addEventListener%28%27click%27%2C%20test%2C%20false%29%3B%0A%20document.getElementsByTagName%28%27a%27%29%5B0%5D.addEventListener%28%27DOMActivate%27%2C%20test%2C%20false%29%3B%0A%20document.getElementsByTagName%28%27p%27%29%5B0%5D.addEventListener%28%27click%27%2C%20test%2C%20false%29%3B%0A%20document.getElementsByTagName%28%27p%27%29%5B0%5D.addEventListener%28%27DOMActivate%27%2C%20test%2C%20false%29%3B%0A%3C/script%3E%0A
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20HTML%3E%0A%3Ca%20href%3Dhttp%3A//google.com/%20target%3Da%3EA%3C/a%3E%3Ca%20href%3Dhttp%3A//yahoo.com/%20target%3Db%3EB%3C/a%3E%3Cbr%3E%0A%3Ciframe%20name%3Da%3E%3C/iframe%3E%3Ciframe%20name%3Db%3E%3C/iframe%3E%0A%3Cscript%3E%0A%20var%20a%20%3D%20document.getElementsByTagName%28%27a%27%29%5B0%5D%3B%0A%20var%20b%20%3D%20document.getElementsByTagName%28%27a%27%29%5B1%5D%3B%0A%20a.appendChild%28b%29%3B%0A%3C/script%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20HTML%3E%0A%3Cform%20action%3D%22http%3A//google.com/%22%20onsubmit%3D%22w%28%27onsubmit%27%29%22%3E%3Cem%3EA%3C/em%3E%3C/form%3E%0A%3Cscript%3E%0Adocument.getElementsByTagName%28%27form%27%29%5B0%5D.attachEvent%28%27onsubmit%27%2C%20function%20%28%29%20%7B%20w%28%27submit%20fired%27%29%20%7D%29%3B%0Adocument.getElementsByTagName%28%27form%27%29%5B0%5D.fireEvent%28%27onsubmit%27%29%3B%0A%3C/script%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20HTML%3E%0A%3Cform%20action%3D%22http%3A//google.com/%22%3EX%3C/form%3E%0A%3Cscript%3E%0Avar%20evt%20%3D%20document.createEvent%28%22Events%22%29%3B%0Aevt.initEvent%28%22submit%22%2C%20true%2C%20true%29%3B%0Adocument.getElementsByTagName%28%27form%27%29%5B0%5D.dispatchEvent%28evt%29%3B%0A%3C/script%3E
-->
<p><dfn>Interactive content</dfn> is content that is specifically
intended for user interaction.</p>
<ul class="brief category-list">
<li><code>a</code></li>
<li><code>audio</code> (if the <code title="attr-media-controls">controls</code> attribute is present)</li>
<li><code>button</code></li>
<!-- v2DATAGRID <li><code>datagrid</code></li> -->
<li><code>details</code></li>
<li><code>embed</code></li>
<li><code>iframe</code></li>
<li><code>img</code> (if the <code title="attr-hyperlink-usemap">usemap</code> attribute is present)</li>
<li><code>input</code> (if the <code title="attr-input-type">type</code> attribute is <em>not</em> in the <span title="attr-input-type-hidden">Hidden</span> state)</li>
<li><code>keygen</code></li>
<li><code>label</code></li>
<li><code>menu</code> (if the <code title="attr-menu-type">type</code> attribute is in the <span title="toolbar state">toolbar</span> state)</li>
<li><code>object</code> (if the <code title="attr-hyperlink-usemap">usemap</code> attribute is present)<!-- see also comment in <object> section --></li>
<li><code>select</code></li>
<li><code>textarea</code></li>
<li><code>video</code> (if the <code title="attr-media-controls">controls</code> attribute is present)</li>
</ul>
<p>Certain elements in HTML have an <span>activation
behavior</span>, which means that the user can activate them. This
triggers a sequence of events dependent on the activation mechanism,
and normally culminating in a <code title="event-click">click</code>
event followed by a <code
title="event-DOMActivate">DOMActivate</code> event<span
class="impl">, as described below</span>.</p>
<div class="impl">
<p>The user agent should allow the user to manually trigger elements
that have an <span>activation behavior</span>, for instance using
keyboard or voice input, or through mouse clicks. When the user
triggers an element with a defined <span>activation behavior</span>
in a manner other than clicking it, the default action of the
interaction event must be to <span>run synthetic click activation
steps</span> on the element.</p> <!-- interaction event spec point -->
<p>When a user agent is to <dfn>run synthetic click activation
steps</dfn> on an element, the user agent must <span>run pre-click
activation steps</span> on the element, then <span>fire a <code
title="event-click">click</code> event</span> at the element. The
default action of this <span title="event-click">click</span> event
must be to <span>run post-click activation steps</span> on the
element. If the event is canceled, the user agent must <span>run
canceled activation steps</span> on the element instead.</p>
<p>Given an element <var title="">target</var>, the <dfn>nearest
activatable element</dfn> is the element returned by the following
algorithm:</p>
<ol>
<li><p>If <var title="">target</var> has a defined <span>activation
behavior</span>, then return <var title="">target</var> and abort
these steps.</p></li>
<li><p>If <var title="">target</var> has a parent element, then set
<var title="">target</var> to that parent element and return to the
first step.</p></li>
<li><p>Otherwise, there is no <span>nearest activatable
element</span>.</p></li>
</ol>
<p>When a pointing device is clicked, the user agent must run these
steps:</p>
<ol>
<li><p>Let <var title="">e</var> be the <span title="">nearest
activatable element</span> of the element designated by the user,
if any.</p></li>
<li><p>If there is an element <var title="">e</var>, <span>run
pre-click activation steps</span> on it.</p></li>
<li>
<p>Dispatch the required <code title="event-click">click</code>
event.</p> <!-- interaction event spec point -->
<p>If there is an element <var title="">e</var>, then the default
action of the <span title="event-click">click</span> event must be
to <span>run post-click activation steps</span> on element <var
title="">e</var>.</p>
<p>If there is an element <var title="">e</var> but the event is
canceled, the user agent must <span>run canceled activation
steps</span> on element <var title="">e</var>.</p>
</li>
</ol>
<p class="note">The above doesn't happen for arbitrary synthetic
events dispatched by author script. However, the <code
title="dom-click">click()</code> method can be used to make it
happen programmatically.</p>
<p>When a user agent is to <dfn>run pre-click activation steps</dfn>
on an element, it must run the <dfn>pre-click activation steps</dfn>
defined for that element, if any.</p>
<p>When a user agent is to <dfn>run post-click activation
steps</dfn> on an element, the user agent must <span>fire a simple
event</span> named <code
title="event-DOMActivate">DOMActivate</code> that is cancelable at
that element. The default action of this event must be to <span>run
final activation steps</span> on that element. If the event is
canceled, the user agent must <span>run canceled activation
steps</span> on the element instead.</p>
<p>When a user agent is to <dfn>run canceled activation steps</dfn>
on an element, it must run the <dfn>canceled activation steps</dfn>
defined for that element, if any.</p>
<p>When a user agent is to <dfn>run final activation steps</dfn> on
an element, it must run the <dfn>activation behavior</dfn> defined
for that element. Activation behaviors can refer to the <code
title="event-click">click</code> and <code
title="event-DOMActivate">DOMActivate</code> events that were fired
by the steps above leading up to this point.</p>
</div>
<h5>Transparent content models</h5>
<p>Some elements are described as <dfn>transparent</dfn>; they have
"transparent" in the description of their content model.</p>
<p>When a content model includes a part that is "transparent", those
parts must not contain content that would not be conformant if all
transparent elements in the tree were replaced, in their parent
element, by the children in the "transparent" part of their content
model, retaining order.</p>
<div class="example">
<p>Consider the following markup fragment:</p>
<pre><p>Hello <a href="world.html"><em>wonderful</em> world</a>!</p></pre>
<p>Its DOM looks like the following:</p>
<ul class="domTree"><li class="t1"><code>p</code><ul><li class="t3"><code>#text</code>: <span title="">Hello </span></li><li class="t1"><code>a</code> <span class="t2" title=""><code class="attribute name">href</code>="<code class="attribute value">world.html</code>"</span><ul><li class="t1"><code>em</code><ul><li class="t3"><code>#text</code>: <span title="">wonderful</span></li></ul></li><li class="t3"><code>#text</code>: <span title=""> world</span></li></ul></li><li class="t3"><code>#text</code>: <span title="">!</span></li></ul></li></ul>
<p>The content model of the <code>a</code> element is
<span>transparent</span>. To see if its contents are conforming,
therefore, the element is replaced by its contents:</p>
<ul class="domTree"><li class="t1"><code>p</code><ul><li class="t3"><code>#text</code>: <span title="">Hello </span></li><li class="t1"><code>em</code><ul><li class="t3"><code>#text</code>: <span title="">wonderful</span></li></ul></li><li class="t3"><code>#text</code>: <span title=""> world</span></li><li class="t3"><code>#text</code>: <span title="">!</span></li></ul></li></ul>
<p>Since that is conforming, the contents of the <code>a</code> are
conforming in the original fragment.</p>
</div>
<p>When a transparent element has no parent, then the part of its
content model that is "transparent" must instead be treated as
accepting any <span>flow content</span>.</p>
<h5>Paragraphs</h5>
<p class="note">The term <span>paragraph</span> as defined in this
section is distinct from (though related to) the <code>p</code>
element defined later. The <span>paragraph</span> concept defined
here is used to describe how to interpret documents.</p>
<p>A <dfn>paragraph</dfn> is typically a run of <span>phrasing
content</span> that forms a block of text with one or more sentences
that discuss a particular topic, as in typography, but can also be
used for more general thematic grouping. For instance, an address is
also a paragraph, as is a part of a form, a byline, or a stanza in a
poem.</p>
<div class="example">
<p>In the following example, there are two paragraphs in a
section. There is also a heading, which contains phrasing content
that is not a paragraph. Note how the comments and
<span>inter-element whitespace</span> do not form paragraphs.</p>
<pre><section>
<h1>Example of paragraphs</h1>
This is the <em>first</em> paragraph in this example.
<p>This is the second.</p>
<!-- This is not a paragraph. -->
</section></pre>
</div>
<p>Paragraphs in <span>flow content</span> are defined relative to
what the document looks like without the <code>a</code>,
<code>ins</code>, <code>del</code>, and <code>map</code> elements
complicating matters, since those elements, with their hybrid
content models, can straddle paragraph boundaries, as shown in the
first two examples below.</p>
<p class="note">Generally, having elements straddle paragraph
boundaries is best avoided. Maintaining such markup can be
difficult.</p>
<div class="example">
<p>The following example takes the markup from the earlier example
and puts <code>ins</code> and <code>del</code> elements around some
of the markup to show that the text was changed (though in this
case, the changes admittedly don't make much sense). Notice how
this example has exactly the same paragraphs as the previous one,
despite the <code>ins</code> and <code>del</code> elements —
the <code>ins</code> element straddles the heading and the first
paragraph, and the <code>del</code> element straddles the boundary
between the two paragraphs.</p>
<pre><section>
<ins><h1>Example of paragraphs</h1>
This is the <em>first</em> paragraph in</ins> this example<del>.
<p>This is the second.</p></del>
<!-- This is not a paragraph. -->
</section></pre>
</div>
<div class="impl">
<p>Let <var title="">view</var> be a view of the DOM that replaces
all <code>a</code>, <code>ins</code>, <code>del</code>, and
<code>map</code> elements in the document with their contents. Then,
in <var title="">view</var>, for each run of sibling <span>phrasing
content</span> nodes uninterrupted by other types of content, in an
element that accepts content other than <span>phrasing
content</span>, let <var title="">first</var> be the first node of
the run, and let <var title="">last</var> be the last node of the
run. For each such run that consists of at least one node that is
neither <span>embedded content</span> nor <span>inter-element
whitespace</span>, a paragraph exists in the original DOM from
immediately before <var title="">first</var> to immediately after
<var title="">last</var>. (Paragraphs can thus span across
<code>a</code>, <code>ins</code>, <code>del</code>, and
<code>map</code> elements.)</p>
<p>Conformance checkers may warn authors of cases where they have
paragraphs that overlap each other (this can happen with
<code>object</code>, <code>video</code>, <code>audio</code>, and
<code>canvas</code> elements).</p> <!-- example below -->
</div>
<p>A <span>paragraph</span> is also formed explicitly by
<code>p</code> elements.</p>
<p class="note">The <code>p</code> element can be used to wrap
individual paragraphs when there would otherwise not be any content
other than phrasing content to separate the paragraphs from each
other.</p>
<div class="example">
<p>In the following example, the link spans half of the first
paragraph, all of the heading separating the two paragraphs, and
half of the second paragraph. It straddles the paragraphs and the
heading.</p>
<pre><aside>
Welcome!
<a href="about.html">
This is home of...
<h1>The Falcons!</h1>
The Lockheed Martin multirole jet fighter aircraft!
</a>
This page discusses the F-16 Fighting Falcon's innermost secrets.
</aside></pre>
<p>Here is another way of marking this up, this time showing the
paragraphs explicitly, and splitting the one link element into
three:</p>
<pre><aside>
<p>Welcome! <a href="about.html">This is home of...</a></p>
<h1><a href="about.html">The Falcons!</a></h1>
<p><a href="about.html">The Lockheed Martin multirole jet
fighter aircraft!</a> This page discusses the F-16 Fighting
Falcon's innermost secrets.</p>
</aside></pre>
</div>
<div class="example">
<!-- I don't know if there's a better way to deal with this, but if
there is, let me know... -->
<p>It is possible for paragraphs to overlap when using certain
elements that define fallback content. For example, in the
following section:</p>
<pre><section>
<h1>My Cats</h1>
You can play with my cat simulator.
<object data="cats.sim">
To see the cat simulator, use one of the following links:
<ul>
<li><a href="cats.sim">Download simulator file</a>
<li><a href="http://sims.example.com/watch?v=LYds5xY4INU">Use online simulator</a>
</ul>
Alternatively, upgrade to the Mellblom Browser.
</object>
I'm quite proud of it.
</section></pre>
<p>There are five paragraphs:</p>
<ol class="brief">
<li>The paragraph that says "You can play with my cat
simulator. <i title="">object</i> I'm quite proud of it.", where
<i title="">object</i> is the <code>object</code> element.</li>
<li>The paragraph that says "To see the cat simulator, use one of
the following links:".</li>
<li>The paragraph that says "Download simulator file".</li>
<li>The paragraph that says "Use online simulator".</li>
<li>The paragraph that says "Alternatively, upgrade to the Mellblom Browser.".</li>
</ol>
<p>The first paragraph is overlapped by the other four. A user
agent that supports the "cats.sim" resource will only show the
first one, but a user agent that shows the fallback will
confusingly show the first sentence of the first paragraph as
if it was in the same paragraph as the second one, and will show
the last paragraph as if it was at the start of the second sentence
of the first paragraph.</p>
<p>To avoid this confusion, explicit <code>p</code> elements can be
used.</p>
</div>
<h4><dfn>Annotations for assistive technology products</dfn> (ARIA)</h4>
<p>Authors may use the ARIA <code title="attr-aria-role">role</code>
and <code title="attr-aria-*">aria-*</code> attributes on <span>HTML
elements</span>, in accordance with the requirements described in
the ARIA specifications, except where these conflict with the
<span>strong native semantics</span> described below. These
exceptions are intended to prevent authors from making assistive
technology products report nonsensical states that do not represent
the actual state of the document. <a href="#refsARIA">[ARIA]</a></p>
<div class="impl">
<p>User agents are required to implement ARIA semantics on all
<span>HTML elements</span>, as defined in the ARIA
specifications. The <span>implicit ARIA semantics</span> defined
below must be recognised by implementations. <a
href="#refsARIAIMPL">[ARIAIMPL]</a></p>
</div>
<p>The following table defines the <span>strong native
semantics</span> <span class="impl">and corresponding <span>implicit
ARIA semantics</span></span> that apply to <span>HTML
elements</span>. Each language feature (element or attribute) in a
cell in the first column implies the ARIA semantics (role, states,
and/or properties) given in the cell in the second column of the
same row. Authors must not set the ARIA <code
title="attr-aria-role">role</code> and <code
title="attr-aria-*">aria-*</code> attributes in a manner that
conflicts with the semantics described in the following table. <span
class="impl">When multiple rows apply to an element, the role from
the last row to define a role must be applied, and the states and
properties from all the rows must be combined.</span></p>
<table>
<thead>
<tr>
<th>Language feature
<th>Strong native semantics <span class="impl">and implied ARIA semantics</span>
<tbody>
<tr>
<td><code>a</code> element that represents a <span>hyperlink</span>
<td><code title="attr-aria-role-link">link</code> role
<tr>
<td><code>address</code> element
<td><code title="attr-aria-role-contentinfo">contentinfo</code> role
<tr>
<td><code>area</code> element that represents a <span>hyperlink</span>
<td><code title="attr-aria-role-link">link</code> role
<tr>
<td><code>button</code> element
<td><code title="attr-aria-role-button">button</code> role
<tr>
<td><code>datalist</code> element
<td><code title="attr-aria-role-listbox">listbox</code> role, with the <code title="attr-aria-multiselectable">aria-multiselectable</code> property set to "false"
<tr>
<td><code>footer</code> element
<td><code title="attr-aria-role-contentinfo">contentinfo</code> role
<tr>
<td><code>h1</code> element that does not have an <code>hgroup</code> ancestor
<td><code title="attr-aria-role-heading">heading</code> role, with the <code title="attr-aria-level">aria-level</code> property set to the element's <span>outline depth</span>
<tr>
<td><code>h2</code> element that does not have an <code>hgroup</code> ancestor
<td><code title="attr-aria-role-heading">heading</code> role, with the <code title="attr-aria-level">aria-level</code> property set to the element's <span>outline depth</span>
<tr>
<td><code>h3</code> element that does not have an <code>hgroup</code> ancestor
<td><code title="attr-aria-role-heading">heading</code> role, with the <code title="attr-aria-level">aria-level</code> property set to the element's <span>outline depth</span>
<tr>
<td><code>h4</code> element that does not have an <code>hgroup</code> ancestor
<td><code title="attr-aria-role-heading">heading</code> role, with the <code title="attr-aria-level">aria-level</code> property set to the element's <span>outline depth</span>
<tr>
<td><code>h5</code> element that does not have an <code>hgroup</code> ancestor
<td><code title="attr-aria-role-heading">heading</code> role, with the <code title="attr-aria-level">aria-level</code> property set to the element's <span>outline depth</span>
<tr>
<td><code>h6</code> element that does not have an <code>hgroup</code> ancestor
<td><code title="attr-aria-role-heading">heading</code> role, with the <code title="attr-aria-level">aria-level</code> property set to the element's <span>outline depth</span>
<tr>
<td><code>hgroup</code> element
<td><code title="attr-aria-role-heading">heading</code> role, with the <code title="attr-aria-level">aria-level</code> property set to the element's <span>outline depth</span>
<tr>
<td><code>hr</code> element
<td><code title="attr-aria-role-separator">separator</code> role
<tr>
<td><code>img</code> element whose <code title="attr-img-alt">alt</code> attribute's value is empty
<td><code title="attr-aria-role-presentation">presentation</code> role
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-button">Button</span> state
<td><code title="attr-aria-role-button">button</code> role
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-checkbox">Checkbox</span> state
<td><code title="attr-aria-role-checkbox">checkbox</code> role, with the <code title="attr-aria-checked">aria-checked</code> state set to "mixed" if the element's <code title="dom-input-indeterminate">indeterminate</code> IDL attribute is true, or "true" if the element's <span title="concept-fe-checked">checkedness</span> is true, or "false" otherwise
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-color">Color</span> state
<td>No role
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-date">Date</span> state
<td>No role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-datetime">Date and Time</span> state
<td>No role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-datetime-local">Local Date and Time</span> state
<td>No role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-email">E-mail</span> state with no <span title="concept-input-list">suggestions source element</span>
<td><code title="attr-aria-role-textbox">textbox</code> role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-file">File Upload</span> state
<td><code title="attr-aria-role-button">button</code> role
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-hidden">Hidden</span> state
<td>No role
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-image">Image Button</span> state
<td><code title="attr-aria-role-button">button</code> role
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-month">Month</span> state
<td>No role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-number">Number</span> state
<td><code title="attr-aria-role-spinbutton">spinbutton</code> role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute, the <code title="attr-aria-valuemax">aria-valuemax</code> property set to the element's <span title="concept-input-max">maximum</span>, the <code title="attr-aria-valuemin">aria-valuemin</code> property set to the element's <span title="concept-input-min">minimum</span>, and, if the result of applying the <span>rules for parsing floating point number values</span> to the element's <span title="concept-fe-value">value</span> is a number, with the <code title="attr-aria-valuenow">aria-valuenow</code> property set to that number
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-password">Password</span> state
<td><code title="attr-aria-role-textbox">textbox</code> role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-radio">Radio Button</span> state
<td><code title="attr-aria-role-radio">radio</code> role, with the <code title="attr-aria-checked">aria-checked</code> state set to "true" if the element's <span title="concept-fe-checked">checkedness</span> is true, or "false" otherwise
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-range">Range</span> state
<td><code title="attr-aria-role-slider">slider</code> role, with the <code title="attr-aria-valuemax">aria-valuemax</code> property set to the element's <span title="concept-input-max">maximum</span>, the <code title="attr-aria-valuemin">aria-valuemin</code> property set to the element's <span title="concept-input-min">minimum</span>, and the <code title="attr-aria-valuenow">aria-valuenow</code> property set to the result of applying the <span>rules for parsing floating point number values</span> to the element's <span title="concept-fe-value">value</span>, if that that results in a number, or the <span title="concept-input-value-default-range">default value</span> otherwise
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-reset">Reset Button</span> state
<td><code title="attr-aria-role-button">button</code> role
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-search">Search</span> state with no <span title="concept-input-list">suggestions source element</span>
<td><code title="attr-aria-role-textbox">textbox</code> role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-submit">Submit Button</span> state
<td><code title="attr-aria-role-button">button</code> role
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-tel">Telephone</span> state with no <span title="concept-input-list">suggestions source element</span>
<td><code title="attr-aria-role-textbox">textbox</code> role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-text">Text</span> state with no <span title="concept-input-list">suggestions source element</span>
<td><code title="attr-aria-role-textbox">textbox</code> role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-text">Text</span>, <span title="attr-input-type-search">Search</span>, <span title="attr-input-type-tel">Telephone</span>, <span title="attr-input-type-url">URL</span>, or <span title="attr-input-type-email">E-mail</span> states with a <span title="concept-input-list">suggestions source element</span>
<td><code title="attr-aria-role-combobox">combobox</code> role, with the <code title="attr-aria-owns">aria-owns</code> property set to the same value as the <code title="attr-input-list">list</code> attribute, and the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-time">Time</span> state
<td>No role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-url">URL</span> state with no <span title="concept-input-list">suggestions source element</span>
<td><code title="attr-aria-role-textbox">textbox</code> role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>input</code> element with a <code title="attr-input-type">type</code> attribute in the <span title="attr-input-type-week">Week</span> state
<td>No role, with the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-input-readonly">readonly</code> attribute
<tr>
<td><code>link</code> element that represents a <span>hyperlink</span>
<td><code title="attr-aria-role-link">link</code> role
<tr>
<td><code>menu</code> element with a <code title="attr-menu-type">type</code> attribute in the <span title="context menu state">context menu</span> state
<td>No role
<tr>
<td><code>menu</code> element with a <code title="attr-menu-type">type</code> attribute in the <span title="list state">list</span> state
<td><code title="attr-aria-role-menu">menu</code> role
<tr>
<td><code>menu</code> element with a <code title="attr-menu-type">type</code> attribute in the <span title="toolbar state">toolbar</span> state
<td><code title="attr-aria-role-toolbar">toolbar</code> role
<tr>
<td><code>nav</code> element
<td><code title="attr-aria-role-navigation">navigation</code> role
<tr>
<td><code>option</code> element that is in a <span title="concept-select-option-list">list of options</span> or that represents a suggestion in a <code>datalist</code> element
<td><code title="attr-aria-role-option">option</code> role, with the <code title="attr-aria-selected">aria-selected</code> state set to "true" if the element's <span title="concept-option-selectedness">selectedness</span> is true, or "false" otherwise.
<tr>
<td><code>progress</code> element
<td><code title="attr-aria-role-progressbar">progressbar</code> role, with, if the progress bar is determinate, the <code title="attr-aria-valuemax">aria-valuemax</code> property set to the maximum value of the progress bar, the <code title="attr-aria-valuemin">aria-valuemin</code> property set to zero, and the <code title="attr-aria-valuenow">aria-valuenow</code> property set to the current value of the progress bar
<tr>
<td><code>select</code> element with a <code title="attr-select-multiple">multiple</code> attribute
<td><code title="attr-aria-role-listbox">listbox</code> role, with the <code title="attr-aria-multiselectable">aria-multiselectable</code> property set to "true"
<tr>
<td><code>select</code> element with no <code title="attr-select-multiple">multiple</code> attribute
<td><code title="attr-aria-role-listbox">listbox</code> role, with the <code title="attr-aria-multiselectable">aria-multiselectable</code> property set to "false"
<tr>
<td><code>td</code> element
<td><code title="attr-aria-role-gridcell">gridcell</code> role, with the <code title="attr-aria-labelledby">aria-labelledby</code> property set to the value of the <code title="attr-tdth-headers">headers</code> attribute, if any
<tr>
<td><code>textarea</code> element
<td><code title="attr-aria-role-textbox">textbox</code> role, with the <code title="attr-aria-multiline">aria-multiline</code> property set to "true", and the <code title="title-aria-readonly">aria-readonly</code> state set to "true" if the element has a <code title="attr-textarea-readonly">readonly</code> attribute
<tr>
<td><code>th</code> element that is neither a <span>column header</span> nor a <span>row header</span>
<td><code title="attr-aria-role-gridcell">gridcell</code> role, with the <code title="attr-aria-labelledby">aria-labelledby</code> property set to the value of the <code title="attr-tdth-headers">headers</code> attribute, if any
<tr>
<td><code>th</code> element that is a <span>column header</span>
<td><code title="attr-aria-role-columnheader">columnheader</code> role, with the <code title="attr-aria-labelledby">aria-labelledby</code> property set to the value of the <code title="attr-tdth-headers">headers</code> attribute, if any
<tr>
<td><code>th</code> element that is a <span>row header</span>
<td><code title="attr-aria-role-rowheader">rowheader</code> role, with the <code title="attr-aria-labelledby">aria-labelledby</code> property set to the value of the <code title="attr-tdth-headers">headers</code> attribute, if any
<tr>
<td><code>tr</code> element
<td><code title="attr-aria-role-row">row</code> role
<tr>
<td>An element that <span title="concept-command">defines a command</span>, whose <span title="command-facet-type">Type</span> facet is "checkbox", and that is a descendant of a <code>menu</code> element whose <code title="attr-menu-type">type</code> attribute in the <span title="list state">list</span> state
<td><code title="attr-aria-role-menuitemcheckbox">menuitemcheckbox</code> role, with the <code title="attr-aria-checked">aria-checked</code> state set to "true" if the command's <span title="command-facet-checkedstate">Checked State</span> facet is true, and "false" otherwise
<tr>
<td>An element that <span title="concept-command">defines a command</span>, whose <span title="command-facet-type">Type</span> facet is "command", and that is a descendant of a <code>menu</code> element whose <code title="attr-menu-type">type</code> attribute in the <span title="list state">list</span> state
<td><code title="attr-aria-role-menuitem">menuitem</code> role
<tr>
<td>An element that <span title="concept-command">defines a command</span>, whose <span title="command-facet-type">Type</span> facet is "radio", and that is a descendant of a <code>menu</code> element whose <code title="attr-menu-type">type</code> attribute in the <span title="list state">list</span> state
<td><code title="attr-aria-role-menuitemradio">menuitemradio</code> role, with the <code title="attr-aria-checked">aria-checked</code> state set to "true" if the command's <span title="command-facet-checkedstate">Checked State</span> facet is true, and "false" otherwise
<tr>
<td>Elements that are <span title="concept-fe-disabled">disabled</span>
<td>The <code title="title-aria-disabled">aria-disabled</code> state set to "true"
<tr>
<td>Elements that are <span title="concept-input-required">required</span>
<td>The <code title="title-aria-required">aria-required</code> state set to "true"
</table>
<p>Some <span>HTML elements</span> have native semantics that can be
overridden. The following table lists these elements<span
class="impl"> and their <span>implicit ARIA semantics</span></span>,
along with the restrictions that apply to those elements. Each
language feature (element or attribute) in a cell in the first
column implies, unless otherwise overriden, the ARIA semantic (role,
state, or property) given in the cell in the second column of the
same row, but this semantic may be overridden under the conditions
listed in the cell in the third column of that row.</p>
<table>
<thead>
<tr>
<th>Language feature
<th>Default implied ARIA semantic
<th>Restrictions
<tbody>
<tr>
<td><code>article</code> element
<td><code title="attr-aria-role-article">article</code> role
<td>Role must be either <code title="attr-aria-role-article">article</code>, <code title="attr-aria-role-document">document</code>, <code title="attr-aria-role-application">application</code>, or <code title="attr-aria-role-main">main</code>
<tr>
<td><code>aside</code> element
<td><code title="attr-aria-role-note">note</code> role
<td>Role must be either <code title="attr-aria-role-note">note</code>, <code title="attr-aria-role-complementary">complementary</code>, or <code title="attr-aria-role-search">search</code>
<tr>
<td><code>header</code> element
<td>No role
<td>If specified, role must be <code title="attr-aria-role-banner">banner</code>
<tr>
<td><code>li</code> element whose parent is an <code>ol</code> or <code>ul</code> element
<td><code title="attr-aria-role-listitem">listitem</code> role
<td>Role must be either <code title="attr-aria-role-listitem">listitem</code> or <code title="attr-aria-role-treeitem">treeitem</code>
<tr>
<td><code>ol</code> element
<td><code title="attr-aria-role-list">list</code> role
<td>Role must be either <code title="attr-aria-role-list">list</code>, <code title="attr-aria-role-tree">tree</code>, or <code title="attr-aria-role-directory">directory</code>
<tr>
<td><code>output</code> element
<td><code title="attr-aria-role-status">status</code> role
<td>No restrictions
<tr>
<td><code>section</code> element
<td><code title="attr-aria-role-region">region</code> role
<td>Role must be either <code title="attr-aria-role-region">region</code>, <code title="attr-aria-role-document">document</code>, <code title="attr-aria-role-application">application</code>, <code title="attr-aria-role-contentinfo">contentinfo</code>, <code title="attr-aria-role-main">main</code>, <code title="attr-aria-role-search">search</code>, <code title="attr-aria-role-alert">alert</code>, <code title="attr-aria-role-dialog">dialog</code>, <code title="attr-aria-role-alertdialog">alertdialog</code>, <code title="attr-aria-role-status">status</code>, or <code title="attr-aria-role-log">log</code>
<tr>
<td><code>table</code> element
<td><code title="attr-aria-role-grid">grid</code> role
<td>Role must be either <code title="attr-aria-role-grid">grid</code> or <code title="attr-aria-role-treegrid">treegrid</code>
<tr>
<td><code>ul</code> element
<td><code title="attr-aria-role-list">list</code> role
<td>Role must be either <code title="attr-aria-role-list">list</code> or <code title="attr-aria-role-tree">tree</code>, or <code title="attr-aria-role-directory">directory</code>
<tr>
<td><span>The body element</span>
<td><code title="attr-aria-role-document">document</code> role
<td>Role must be either <code title="attr-aria-role-document">document</code> or <code title="attr-aria-role-application">application</code>
</table>
<div class="impl">
<p>User agents may apply different defaults than those described in
this section in order to expose the semantics of <span>HTML
elements</span> in a manner more fine-grained than possible with the
above definitions.</p>
<p>Conformance checkers are encouraged to phrase errors such that
authors are encouraged to use more appropriate elements rather than
remove accessibility annotations. For example, if an <code>a</code>
element is marked as having the <code
title="attr-aria-role-button">button</code> role, a conformance
checker could say "Either a <code>button</code> element or an
<code>input</code> element is required when using the <code
title="attr-aria-role-button">button</code> role" rather than "The
<code title="attr-aria-role-button">button</code> role cannot be
used with <code>a</code> elements".</p>
</div>
<h3>APIs in HTML documents</h3>
<p>For <span>HTML documents</span>, and for <span>HTML
elements</span> in <span>HTML documents</span>, certain APIs defined
in DOM Core become case-insensitive or case-changing, as sometimes
defined in DOM Core, and as summarized <span class="impl">or
required</span> below. <a href="#refsDOMCORE">[DOMCORE]</a></p>
<p>This does not apply to <span>XML documents</span> or to elements
that are not in the <span>HTML namespace</span> despite being in
<span>HTML documents</span>.</p>
<dl>
<dt><code title="">Element.tagName</code> and <code
title="">Node.nodeName</code></dt>
<dd>
<p>These attributes <span class="impl">must</span> return element
names <span>converted to ASCII uppercase</span>, regardless of the case
with which they were created.</p>
</dd>
<dt><code title="">Document.createElement()</code></dt>
<dd>
<p>The canonical form of HTML markup is all-lowercase; thus, this
method will <span title="converted to ASCII lowercase">lowercase</span>
the argument before creating the requisite element. <span
class="impl">Also, the element created must be in the <span>HTML
namespace</span></span>.</p>
<p class="note">This doesn't apply to <code
title="">Document.createElementNS()</code>. Thus, it is possible,
by passing this last method a tag name in the wrong case, to
create an element that claims to have the tag name of an element
defined in this specification, but doesn't support its interfaces,
because it really has another tag name not accessible from the DOM
APIs.</p>
</dd>
<dt><code title="">Element.setAttribute()</code></dt>
<dt><code title="">Element.setAttributeNode()</code></dt>
<dd>
<p>Attribute names are <span>converted to ASCII lowercase</span>.</p>
<div class="impl">
<p>Specifically: when an attribute is set on an <span title="HTML
elements">HTML element</span> using <code
title="">Element.setAttribute()</code>, the name argument must be
<span>converted to ASCII lowercase</span> before the element is
affected; and when an <code>Attr</code> node is set on an <span
title="HTML elements">HTML element</span> using <code
title="">Element.setAttributeNode()</code>, it must have its name
<span>converted to ASCII lowercase</span> before the element is
affected.</p>
</div>
<p class="note">This doesn't apply to <code
title="">Document.setAttributeNS()</code> and <code
title="">Document.setAttributeNodeNS()</code>.</p>
</dd>
<dt><code title="">Element.getAttribute()</code></dt>
<dt><code title="">Element.getAttributeNode()</code></dt>
<dd>
<p>Attribute names are <span>converted to ASCII lowercase</span>.</p>
<div class="impl">
<p>Specifically: When the <code
title="">Element.getAttribute()</code> method or the <code
title="">Element.getAttributeNode()</code> method is invoked on
an <span title="HTML elements">HTML element</span>, the name
argument must be <span>converted to ASCII lowercase</span> before the
element's attributes are examined.</p>
</div>
<p class="note">This doesn't apply to <code
title="">Document.getAttributeNS()</code> and <code
title="">Document.getAttributeNodeNS()</code>.</p>
</dd>
<dt><code title="">Document.getElementsByTagName()</code></dt>
<dt><code title="">Element.getElementsByTagName()</code></dt>
<dd>
<p>HTML elements match by lower-casing the argument before
comparison, elements from other namespaces are treated as in XML
(case-sensitively).</p>
<div class="impl">
<p>Specifically, these methods (but not their namespaced
counterparts) must compare the given argument in a
<span>case-sensitive</span> manner, but when looking at <span
title="HTML elements">HTML elements</span>, the argument must
first be <span>converted to ASCII lowercase</span>.</p>
</div>
<p class="note">Thus, in an <span title="HTML documents">HTML
document</span> with nodes in multiple namespaces, these methods
will effectively be both case-sensitive and case-insensitive at
the same time.</p>
</dd>
</dl>
<div class="impl">
<h3>Interactions with XPath and XSLT</h3>
<p id="xpath-1.0-processors">Implementations of XPath 1.0 that
operate on HTML documents parsed or created in the manners described
in this specification (e.g. as part of the <code
title="">document.evaluate()</code> API) must act as if the
following edit was applied to the XPath 1.0 specification.</p>
<p>First, remove this paragraph:</p>
<blockquote cite="http://www.w3.org/TR/1999/REC-xpath-19991116#node-tests">
<p>A <a
href="http://www.w3.org/TR/REC-xml-names#NT-QName">QName</a> in the
node test is expanded into an <a
href="http://www.w3.org/TR/1999/REC-xpath-19991116#dt-expanded-name">expanded-name</a>
using the namespace declarations from the expression context. This
is the same way expansion is done for element type names in start
and end-tags except that the default namespace declared with <code
title="">xmlns</code> is not used: if the <a
href="http://www.w3.org/TR/REC-xml-names#NT-QName">QName</a> does
not have a prefix, then the namespace URI is null (this is the same
way attribute names are expanded). It is an error if the <a
href="http://www.w3.org/TR/REC-xml-names#NT-QName">QName</a> has a
prefix for which there is no namespace declaration in the
expression context.</p>
</blockquote>
<p>Then, insert in its place the following:</p>
<blockquote cite="http://www.w3.org/Bugs/Public/show_bug.cgi?id=7059#c37">
<p>A QName in the node test is expanded into an expanded-name using
the namespace declarations from the expression context. If the
QName has a prefix, then there must be a<!-- added 2009-10-27 -
http://www.w3.org/Bugs/Public/show_bug.cgi?id=8062 --> namespace
declaration for this prefix in the expression context, and the
corresponding<!-- typo fixed 2009-10-27 -
http://www.w3.org/Bugs/Public/show_bug.cgi?id=8063 --> namespace
URI is the one that is associated with this prefix. It is an error
if the QName has a prefix for which there is no namespace
declaration in the expression context. </p>
<p>If the QName has no prefix and the principal node type of the
axis is element, then the default element namespace is
used. Otherwise if the QName has no prefix, the namespace URI is
null. The default element namespace is a member of the context for
the XPath expression. The value of the default element namespace
when executing an XPath expression through the DOM3 XPath API is
determined in the following way:</p>
<ol>
<li>If the context node is from an HTML DOM, the default element
namespace is "http://www.w3.org/1999/xhtml".</li>
<li>Otherwise, the default element namespace URI is null.</li>
</ol>
<p class="note">This is equivalent to adding the default element
namespace feature of XPath 2.0 to XPath 1.0, and using the HTML
namespace as the default element namespace for HTML documents. It
is motivated by the desire to have implementations be compatible
with legacy HTML content while still supporting the changes that
this specification introduces to HTML regarding the namespace used
for HTML elements, and by the desire to use XPath 1.0 rather than
XPath 2.0.</p>
</blockquote>
<p class="note">This change is a <span>willful violation</span> of
the XPath 1.0 specification, motivated by desire to have
implementations be compatible with legacy content while still
supporting the changes that this specification introduces to HTML
regarding which namespace is used for HTML elements. <a
href="#refsXPATH10">[XPATH10]</a></p> <!-- note: version matters for
this ref -->
<hr>
<p id="dom-based-xslt-1.0-processors">XSLT 1.0 processors outputting
to a DOM when the output method is "html" (either explicitly or via
the defaulting rule in XSLT 1.0) are affected as follows:</p>
<p>If the transformation program outputs an element in no namespace,
the processor must, prior to constructing the corresponding DOM
element node, change the namespace of the element to the <span>HTML
namespace</span>, <span title="converted to ASCII
lowercase">ASCII-lowercase</span> the element's local name, and
<span title="converted to ASCII lowercase">ASCII-lowercase</span>
the names of any non-namespaced attributes on the element.</p>
<p class="note">This requirement is a <span>willful violation</span>
of the XSLT 1.0 specification, required because this specification
changes the namespaces and case-sensitivity rules of HTML in a
manner that would otherwise be incompatible with DOM-based XSLT
transformations. (Processors that serialize the output are
unaffected.) <a href="#refsXSLT10">[XSLT10]</a></p> <!-- note:
version matters for this ref -->
</div>
<h3><dfn>Dynamic markup insertion</dfn></h3>
<p class="note">APIs for dynamically inserting markup into the
document interact with the parser, and thus their behavior varies
depending on whether they are used with <span>HTML documents</span>
(and the <span>HTML parser</span>) or XHTML in <span>XML
documents</span> (and the <span>XML parser</span>).</p>
<h4>Opening the input stream</h4>
<p>The <dfn title="dom-document-open"><code>open()</code></dfn>
method comes in several variants with different numbers of
arguments.</p>
<dl class="domintro">
<dt><var title="">document</var> = <var title="">document</var> . <code title="dom-document-open">open</code>( [ <var title="">type</var> [, <var title="">replace</var> ] ] )</dt>
<dd>
<p>Causes the <code>Document</code> to be replaced in-place, as if
it was a new <code>Document</code> object, but reusing the
previous object, which is then returned.</p>
<p>If the <var title="">type</var> argument is omitted or has the
value "<code>text/html</code>", then the resulting
<code>Document</code> has an HTML parser associated with it, which
can be given data to parse using <code
title="dom-document-write">document.write()</code>. Otherwise, all
content passed to <code
title="dom-document-write">document.write()</code> will be parsed
as plain text.</p>
<p>If the <var title="">replace</var> argument is present and has
the value "<code title="">replace</code>", the existing entries in
the session history for the <code>Document</code> object are
removed.</p>
<p>The method has no effect if the <code>Document</code> is still
being parsed.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if the
<code>Document</code> is an <span title="XML documents">XML
document</span>.</p>
</dd>
<dt><var title="">window</var> = <var title="">document</var> . <code title="dom-document-open">open</code>( <var title="">url</var>, <var title="">name</var>, <var title="">features</var> [, <var title="">replace</var> ] )</dt>
<dd>
<p>Works like the <code title="dom-open">window.open()</code>
method.</p>
</dd>
</dl>
<div class="impl">
<p>When called with two or fewer arguments, the method must act as
follows:</p>
<ol>
<li>If the <code>Document</code> object is not flagged as an <span
title="HTML documents">HTML document</span>, throw an
<code>INVALID_STATE_ERR</code> exception and abort these
steps.</li>
<li><p>Let <var title="">type</var> be the value of the first
argument, if there is one, or "<code>text/html</code>"
otherwise.</p></li>
<li><p>Let <var title="">replace</var> be true if there is a second
argument and it is an <span>ASCII case-insensitive</span> match for
the value "replace", and false otherwise.</p></li>
<li>
<p>If the document has an <span>active parser</span> that isn't a
<span>script-created parser</span>, and the <span>insertion
point</span> associated with that parser's <span>input
stream</span> is not undefined (that is, it <em>does</em> point to
somewhere in the input stream), then the method does
nothing. Abort these steps and return the <code>Document</code>
object on which the method was invoked.</p>
<p class="note">This basically causes <code
title="dom-document-open">document.open()</code> to be ignored
when it's called in an inline script found during the parsing of
data sent over the network, while still letting it have an effect
when called asynchronously or on a document that is itself being
spoon-fed using these APIs.</p>
</li>
<li><p>Release the <span>storage mutex</span>.</p></li>
<li><p><span title="prompt to unload a document">Prompt to
unload</span> the <code>Document</code> object. If the user
<span>refused to allow the document to be unloaded</span>, then
these steps must be aborted.</p></li>
<li><p><span title="unload a document">Unload</span> the
<code>Document</code> object, with the <var title="">recycle</var>
parameter set to true.</p></li>
<li><p>If the document has an <span>active parser</span>, then
abort that parser, and throw away any pending content in the
<span>input stream</span>.</p></li>
<li><p>Unregister all event listeners registered on the
<code>Document</code> node and its descendants.</p>
<li><p>Remove any <span title="concept-task">tasks</span>
associated with the <code>Document</code> in any <span>task
source</span>.</p></li> <!-- removes callbacks that fired between
this algorithm starting and the times and databases being aborted
in the "unload" step above -->
<li><p>Remove all child nodes of the document, without firing any
mutation events.</p></li> <!-- as of 2009-03-30, only WebKit fired
mutation events here. -->
<li><p>Replace the <code>Document</code>'s singleton objects with
new instances of those objects. (This includes in particular the
<code>Window</code>, <code>Location</code>, <code>History</code>,
<code>ApplicationCache</code>, <code>UndoManager</code>,
<code>Navigator</code>, and <code>Selection</code> objects, the
various <code>BarProp</code> objects, the two <code>Storage</code>
objects, and the various <code>HTMLCollection</code> objects. It
also includes all the Web IDL prototypes in the JavaScript binding,
including the <code>Document</code> object's prototype.)</p></li>
<!-- http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...%3Ciframe%20src%3D%22document%22%3E%3C%2Fiframe%3E%0A%3Cscript%3Eonload%20%3D%20function%20()%20%7B%20f%20%3D%20document.getElementsByTagName('iframe')%5B0%5D%3B%20d%20%3D%20f.contentWindow.document%3B%20%7D%3C%2Fscript%3E%0A%3Cinput%20type%3Dbutton%20onclick%3D%22w(d.documentElement.innerHTML)%22%20value%3D%22dump%22%3E%0A%3Cinput%20type%3Dbutton%20onclick%3D%22d.open()%3B%20d.write('%3Cscript%3Evar%20x%20%3D%20new%20XMLHttpRequest()%3Bx.open(%26quot%3BGET%26quot%3B%2C%20%26quot%3BGET%26quot%3B)%3Bx.onreadystatechange%3Dfunction()%20%7B%20alert(x.readyState)%3B%20%7D%3Bx.send(null)%3B%3C%2Fscript%3E')%3Bd.close()%3B%20setTimeout(function()%20%7B%20d.open()%3B%20d.write('%3Cp%3Etest%3C%2Fp%3E')%3B%20d.close()%20%7D%2C%200)%3B%22%20value%3D%22xhr%22%3E%0A%3Cinput%20type%3Dbutton%20onclick%3D%22d.onclick%20%3D%20function()%20%7B%20w('click')%20%7D%22%20value%3D%22add%20click%20handler%22%3E%0A%3Cinput%20type%3Dbutton%20onclick%3D%22d.open()%3B%20d.write('%3Cp%3Etest%3C%2Fp%3E')%3B%20d.close()%22%20value%3D%22replace%22%3E%0A%3Cinput%20type%3Dbutton%20onclick%3D%22d.open()%3B%20d.write('%3Cp%3E%3Cscript%3Ei%20%3D%200%3B%20setTimeout(%26quot%3Bparent.w(i%2B%2B)%26quot%3B%2C%202000)%3C%2Fscript%3E%3C%2Fp%3E')%3B%20d.close()%22%20value%3D%22replace%20with%20timer%22%3E -->
<!-- http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0D%0A...%3Ciframe%3E%3C%2Fiframe%3E%0D%0A%3Cscript%3E%0D%0Aonload%20%3D%20function%20()%20%7B%0D%0A%20frames%5B0%5D.test%20%3D%201%0D%0A%20w(frames%5B0%5D.test)%3B%0D%0A%20var%20a%20%3D%20frames%5B0%5D.document.location.assign%3B%0D%0A%20w(a)%3B%0D%0A%20w(frames%5B0%5D.document.location.assign%20%3D%3D%3D%20a)%3B%0D%0A%20frames%5B0%5D.document.open()%3B%0D%0A%20frames%5B0%5D.document.write('%3Cscript%3Edocument.write(test)%3C%5C%2Fscript%3E')%3B%0D%0A%20frames%5B0%5D.document.close()%3B%0D%0A%20w(frames%5B0%5D.test)%3B%0D%0A%20w(frames%5B0%5D.document.location.assign%20%3D%3D%3D%20a)%3B%0D%0A%7D%0D%0A%3C%2Fscript%3E -->
<li><p>Change the <span>document's character encoding</span> to
UTF-16.</p></li>
<li><p>Change <span>the document's address</span> to the
<span>first script</span>'s <span title="script's browsing
context">browsing context</span>'s <span>active document</span>'s
<span title="the document's address">address</span>.</p></li>
<li><p>Create a new <span>HTML parser</span> and associate it with
the document. This is a <dfn>script-created parser</dfn> (meaning
that it can be closed by the <code
title="dom-document-open">document.open()</code> and <code
title="dom-document-close">document.close()</code> methods, and
that the tokenizer will wait for an explicit call to <code
title="dom-document-close">document.close()</code> before emitting
an end-of-file token). The encoding <span
title="concept-encoding-confidence">confidence</span> is
<i>irrelevant</i>.</p></li>
<li>
<!-- text/plain handling -->
<p>If the <var title="">type</var> string contains a U+003B
SEMICOLON character (;), remove the first such character and all
characters from it up to the end of the string.</p>
<p>Strip all leading and trailing <span title="space
character">space characters</span> from <var
title="">type</var>.</p>
<p>If <var title="">type</var> is <em>not</em> now an <span>ASCII
case-insensitive</span> match for the string
"<code>text/html</code>", then act as if the tokenizer had emitted
a start tag token with the tag name "pre", then switch the
<span>HTML parser</span>'s tokenizer to the <span>PLAINTEXT
state</span>.</p>
<!--
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...%3Ciframe%3E%3C%2Fiframe%3E%3Cscript%3Eonload%20%3D%20function%20()%20%7B%20%0D%0A%20%20var%20d%20%3D%20document.getElementsByTagName('iframe')%5B0%5D.contentDocument%3B%0D%0A%20%20d.open('image%2Fsvg%2Bxml')%3B%0D%0A%20%20d.write(%22%3Cinput%20xmlns%3D'http%3A%2F%2Fwww.w3.org%2F1999%2Fxhtml'%20value%3D'(x)html'%2F%3E%22)%3B%0D%0A%20%20d.close()%3B%0D%0A%7D%3B%3C%2Fscript%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...%3Ciframe%3E%3C%2Fiframe%3E%3Cscript%3Eonload%20%3D%20function%20()%20%7B%20%0D%0A%20%20var%20d%20%3D%20document.getElementsByTagName('iframe')%5B0%5D.contentDocument%3B%0D%0A%20%20d.open('image%2Fgif')%3B%0D%0A%20%20var%20a%20%3D%20%5B%200x47%2C%200x49%2C%200x46%2C%200x38%2C%200x39%2C%200x61%2C%200x01%2C%200x00%2C%200x01%2C%200x00%2C%0D%0A%20%20%20%20%20%20%20%20%20%20%20%200x80%2C%200xff%2C%200x00%2C%200xc0%2C%200xc0%2C%200xc0%2C%200x00%2C%200x00%2C%200x00%2C%200x21%2C%0D%0A%20%20%20%20%20%20%20%20%20%20%20%200xf9%2C%200x04%2C%200x01%2C%200x00%2C%200x00%2C%200x00%2C%200x00%2C%200x2c%2C%200x00%2C%200x00%2C%0D%0A%20%20%20%20%20%20%20%20%20%20%20%200x00%2C%200x00%2C%200x01%2C%200x00%2C%200x01%2C%200x00%2C%200x00%2C%200x02%2C%200x02%2C%200x44%2C%0D%0A%20%20%20%20%20%20%20%20%20%20%20%200x01%2C%200x00%2C%200x3b%20%5D%3B%0D%0A%20%20var%20s%20%3D%20%22%22%3B%0D%0A%20%20for%20(var%20i%20%3D%200%3B%20i%20%3C%20a.length%3B%20i%20%2B%3D%201)%0D%0A%20%20%20%20s%20%2B%3D%20String.fromCharCode(a%5Bi%5D)%3B%0D%0A%20%20d.write(s)%3B%0D%0A%20%20d.close()%3B%0D%0A%7D%3B%3C%2Fscript%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...%3Ciframe%3E%3C%2Fiframe%3E%3Cscript%3Eonload%20%3D%20function%20()%20{%20%0A%20%20var%20d%20%3D%20document.getElementsByTagName(%27iframe%27)[0].contentDocument%3B%0A%20%20d.open(%27Text%2Fplain%27)%3B%0A%20%20d.write(%27%3Cb%3Etest%27)%3B%0A%20%20d.close()%3B%0A}%3B%3C%2Fscript%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...%3Ciframe%3E%3C%2Fiframe%3E%3Cscript%3Eonload%20%3D%20function%20()%20{%20%0A%20%20var%20d%20%3D%20document.getElementsByTagName(%27iframe%27)[0].contentDocument%3B%0A%20%20d.open(%27%20text%2Fplain%27)%3B%0A%20%20d.write(%27%3Cb%3Etest%27)%3B%0A%20%20d.close()%3B%0A}%3B%3C%2Fscript%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...%3Ciframe%3E%3C%2Fiframe%3E%3Cscript%3Eonload%20%3D%20function%20()%20{%20%0A%20%20var%20d%20%3D%20document.getElementsByTagName(%27iframe%27)[0].contentDocument%3B%0A%20%20d.open(%27text%2Fplain%3B%27)%3B%0A%20%20d.write(%27%3Cb%3Etest%27)%3B%0A%20%20d.close()%3B%0A}%3B%3C%2Fscript%3E
-->
</li>
<li>
<p>If <var title="">replace</var> is false, then:
<ol>
<li>Remove all the entries in the <span>browsing context</span>'s
<span>session history</span> after the <span>current entry</span>
in its <code>Document</code>'s <code>History</code> object</li>
<li>Remove any earlier entries that share the same
<code>Document</code></li>
<li>Add a new entry just before the last entry that is associated
with the text that was parsed by the previous parser associated
with the <code>Document</code> object, as well as the state of
the document at the start of these steps. (This allows the user
to step backwards in the session history to see the page before
it was blown away by the <code
title="dom-document-open">document.open()</code> call.)</li>
</ol>
</li>
<li><p>Finally, set the <span>insertion point</span> to point at
just before the end of the <span>input stream</span> (which at this
point will be empty).</p></li>
<li><p>Return the <code>Document</code> on which the method was
invoked.</p></li>
</ol>
<p>When called with three or more arguments, the <code
title="dom-document-open">open()</code> method on the
<code>HTMLDocument</code> object must call the <code
title="dom-open">open()</code> method on the <code>Window</code>
object of the <code>HTMLDocument</code> object, with the same
arguments as the original call to the <code
title="dom-document-open">open()</code> method, and return whatever
that method returned. If the <code>HTMLDocument</code> object has no
<code>Window</code> object, then the method must raise an
<code>INVALID_ACCESS_ERR</code> exception.</p>
</div>
<h4>Closing the input stream</h4>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-close">close</code>()</dt>
<dd>
<p>Closes the input stream that was opened by the <code
title="dom-document-open">document.open()</code> method.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if the
<code>Document</code> is an <span title="XML documents">XML
document</span>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-document-close"><code>close()</code></dfn>
method must run the following steps:</p>
<ol>
<li><p>If the <code>Document</code> object is not flagged as an
<span title="HTML documents">HTML document</span>, throw an
<code>INVALID_STATE_ERR</code> exception and abort these
steps.</p></li>
<li><p>If there is no <span>script-created parser</span> associated
with the document, then abort these steps.</p></li>
<li><p>Insert an <span>explicit "EOF" character</span> at the end
of the parser's <span>input stream</span>.</p></li>
<li><p>If there is a <span>pending parsing-blocking script</span>,
then abort these steps.</p></li>
<li><p>Run the tokenizer, processing resulting tokens as they are
emitted, and stopping when the tokenizer reaches the <span>explicit
"EOF" character</span> or <span title="spin the event loop">spins
the event loop</span>.</p></li>
</ol>
</div>
<h4><code title="dom-document-write">document.write()</code></h4>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-write">write</code>(<var title="">text</var>...)</dt>
<dd>
<p>Adds the given string(s) to the <code>Document</code>'s input
stream. If necessary, calls the <code
title="dom-document-open">open()</code> method implicitly
first.</p>
<p>This method throws an <code>INVALID_ACCESS_ERR</code> exception
when invoked on <span>XML documents</span>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-document-write"><code>document.write(...)</code></dfn>
method must act as follows:</p>
<ol>
<li>
<p>If the method was invoked on an <span title="XML documents">XML
document</span>, throw an <code>INVALID_ACCESS_ERR</code>
exception and abort these steps.</p>
<!--
Where would document.write() insert?
Consider: data:text/xml,<script xmlns="http://www.w3.org/1999/xhtml"><![CDATA[ document.write('<foo>Test</foo>'); ]]></script>
-->
</li>
<li>
<p>If the <span>insertion point</span> is undefined, the <code
title="dom-document-open">open()</code> method must be called
(with no arguments) on the <code title="Document">document</code>
object. If the user <span>refused to allow the document to be
unloaded</span>, then these steps must be aborted. Otherwise, the
<span>insertion point</span> will point at just before the end of
the (empty) <span>input stream</span>.</p>
</li>
<li>
<p>The string consisting of the concatenation of all the arguments
to the method must be inserted into the <span>input stream</span>
just before the <span>insertion point</span>.</p>
</li>
<li>
<p>If there is a <span>pending parsing-blocking script</span>, then the
method must now return without further processing of the
<span>input stream</span>.</p>
</li>
<li>
<p>Otherwise, the tokenizer must process the characters that were
inserted, one at a time, processing resulting tokens as they are
emitted, and stopping when the tokenizer reaches the insertion
point or when the processing of the tokenizer is aborted by the
tree construction stage (this can happen if a <code>script</code>
end tag token is emitted by the tokenizer).
<p class="note">If the <code
title="dom-document-write">document.write()</code> method was
called from script executing inline (i.e. executing because the
parser parsed a set of <code>script</code> tags), then this is a
<a href="#nestedParsing">reentrant invocation of the
parser</a>.</p>
</li>
<li>
<p>Finally, the method must return.</p>
</li>
</ol>
</div>
<h4><code title="dom-document-writeln">document.writeln()</code></h4>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-writeln">writeln</code>(<var title="">text</var>...)</dt>
<dd>
<p>Adds the given string(s) to the <code>Document</code>'s input
stream, followed by a newline character. If necessary, calls the
<code title="dom-document-open">open()</code> method implicitly
first.</p>
<p>This method throws an <code>INVALID_ACCESS_ERR</code> exception
when invoked on <span>XML documents</span>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-document-writeln"><code>document.writeln(...)</code></dfn>
method, when invoked, must act as if the <code
title="dom-document-write">document.write()</code> method had been
invoked with the same argument(s), plus an extra argument consisting
of a string containing a single line feed character (U+000A).</p>
</div>
<h4><code title="dom-innerHTML">innerHTML</code></h4>
<p>The <dfn title="dom-innerHTML"><code>innerHTML</code></dfn> IDL
attribute represents the markup of the node's contents.</p>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-innerHTML">innerHTML</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns a fragment of HTML or XML that represents the
<code>Document</code>.</p>
<p>Can be set, to replace the <code>Document</code>'s contents
with the result of parsing the given string.</p>
<p>In the case of <span>XML documents</span>, will throw an
<code>INVALID_STATE_ERR</code> if the <code>Document</code> cannot
be serialized to XML, and a <code>SYNTAX_ERR</code> if the given
string is not well-formed.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-innerHTML">innerHTML</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns a fragment of HTML or XML that represents the element's
contents.</p>
<p>Can be set, to replace the contents of the element with nodes
parsed from the given string.</p>
<p>In the case of <span>XML documents</span>, will throw an
<code>INVALID_STATE_ERR</code> if the element cannot be serialized
to XML, and a <code>SYNTAX_ERR</code> if the given string is not
well-formed.</p>
</dd>
</dl>
<div class="impl">
<p>On getting, if the node's document is an <span title="HTML
documents">HTML document</span>, then the attribute must return the
result of running the <span>HTML fragment serialization
algorithm</span> on the node; otherwise, the node's document is an
<span title="XML documents">XML document</span>, and the attribute
must return the result of running the <span>XML fragment
serialization algorithm</span> on the node instead (this might raise
an exception instead of returning a string).</p>
<p>On setting, the following steps must be run:</p>
<ol>
<li>
<p>If the node's document is an <span title="HTML documents">HTML
document</span>: Invoke the <span>HTML fragment parsing
algorithm</span>.</p>
<p>If the node's document is an <span title="XML documents">XML
document</span>: Invoke the <span>XML fragment parsing
algorithm</span>.</p>
<p>In either case, the algorithm must be invoked with the string
being assigned into the <code
title="dom-innerHTML">innerHTML</code> attribute as the <var
title="">input</var>. If the node is an <code>Element</code>
node, then, in addition, that element must be passed as the <var
title="">context</var> element.</p>
<p>If this raises an exception, then abort these steps.</p>
<p>Otherwise, let <var title="">new children</var> be the nodes
returned.</p>
</li>
<li>
<p>If the attribute is being set on a <code>Document</code> node,
and that document has an <span>active parser</span>, then abort
that parser.</p>
</li>
<li>
<p>Remove the child nodes of the node whose <code
title="dom-innerHTML">innerHTML</code> attribute is being set,
firing appropriate mutation events.</p>
</li>
<li>
<p>If the attribute is being set on a <code>Document</code>
node, let <var title="">target document</var> be that
<code>Document</code> node. Otherwise, the attribute is being
set on an <code>Element</code> node; let <var title="">target
document</var> be the <code title="">ownerDocument</code> of
that <code>Element</code>.</p>
</li>
<li>
<p>Set the <code title="">ownerDocument</code> of all the nodes in
<var title="">new children</var> to the <var title="">target
document</var>.</p>
</li>
<li>
<p>Append all the <var title="">new children</var> nodes to the
node whose <code title="dom-innerHTML">innerHTML</code> attribute
is being set, preserving their order, and firing mutation events
as if a <code>DocumentFragment</code> containing the <var
title="">new children</var> had been inserted.</p>
</li>
</ol>
</div>
<h4><code title="dom-outerHTML">outerHTML</code></h4>
<p>The <dfn title="dom-outerHTML"><code>outerHTML</code></dfn> IDL
attribute represents the markup of the element and its contents.</p>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-outerHTML">outerHTML</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns a fragment of HTML or XML that represents the element
and its contents.</p>
<p>Can be set, to replace the element with nodes parsed from the
given string.</p>
<p>In the case of <span>XML documents</span>, will throw an
<code>INVALID_STATE_ERR</code> if the element cannot be serialized
to XML, and a <code>SYNTAX_ERR</code> if the given string is not
well-formed.</p>
<p>Throws a <code>NO_MODIFICATION_ALLOWED_ERR</code> exception if
the parent of the element is the <code>Document</code>
node.</p>
</dd>
</dl>
<div class="impl">
<p>On getting, if the node's document is an <span title="HTML
documents">HTML document</span>, then the attribute must return the
result of running the <span>HTML fragment serialization
algorithm</span> on a fictional node whose only child is the node on
which the attribute was invoked; otherwise, the node's document is
an <span title="XML documents">XML document</span>, and the
attribute must return the result of running the <span>XML fragment
serialization algorithm</span> on that fictional node instead (this
might raise an exception instead of returning a string).</p>
<p>On setting, the following steps must be run:</p>
<ol>
<li>
<p>Let <var title="">target</var> be the element whose <code
title="dom-outerHTML">outerHTML</code> attribute is being
set.</p>
</li>
<li>
<p>If <var title="">target</var> has no parent node, then abort
these steps. There would be no way to obtain a reference to the
nodes created even if the remaining steps were run.</p>
</li>
<li>
<p>If <var title="">target</var>'s parent node is a
<code>Document</code> object, throw a
<code>NO_MODIFICATION_ALLOWED_ERR</code> exception and abort these
steps.</p>
</li>
<li>
<p>Let <var title="">parent</var> be <var title="">target</var>'s
parent node, unless that is a <code>DocumentFragment</code> node,
in which case let <var title="">parent</var> be an arbitrary
<code>body</code> element.</p>
</li>
<li>
<p>If <var title="">target</var>'s document is an <span
title="HTML documents">HTML document</span>: Invoke the <span>HTML
fragment parsing algorithm</span>.</p>
<p>If <var title="">target</var>'s document is an <span title="XML
documents">XML document</span>: Invoke the <span>XML fragment
parsing algorithm</span>.</p>
<p>In either case, the algorithm must be invoked with the string
being assigned into the <code
title="dom-outerHTML">outerHTML</code> attribute as the <var
title="">input</var>, and <var title="">parent</var> as the <var
title="">context</var> element.</p>
<p>If this raises an exception, then abort these steps.</p>
<p>Otherwise, let <var title="">new children</var> be the nodes
returned.</p>
</li>
<li>
<p>Set the <code title="">ownerDocument</code> of all the nodes in
<var title="">new children</var> to <var title="">target</var>'s
document.</p>
</li>
<li>
<p>Remove <var title="">target</var> from its parent node, firing
mutation events as appropriate, and then insert in its place all
the <var title="">new children</var> nodes, preserving their
order, and again firing mutation events as if a
<code>DocumentFragment</code> containing the <var title="">new
children</var> had been inserted.</p>
</li>
</ol>
</div>
<h4><code title="dom-insertAdjacentHTML">insertAdjacentHTML()</code></h4>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-insertAdjacentHTML">insertAdjacentHTML</code>(<var title="">position</var>, <var title="">text</var>)</dt>
<dd>
<p>Parses the given string <var title="">text</var> as HTML or XML
and inserts the resulting nodes into the tree in the position
given by the <var title="">position</var> argument, as
follows:</p>
<dl>
<dt>"beforebegin"</dt>
<dd>Before the element itself.</dd>
<dt>"afterbegin"</dt>
<dd>Just inside the element, before its first child.</dd>
<dt>"beforeend"</dt>
<dd>Just inside the element, after its last child.</dd>
<dt>"afterend"</dt>
<dd>After the element itself.</dd>
</dl>
<p>Throws a <code>SYNTAX_ERR</code> exception the arguments have
invalid values (e.g., in the case of <span>XML documents</span>,
if the given string is not well-formed).</p>
<p>Throws a <code>NO_MODIFICATION_ALLOWED_ERR</code> exception if
the given position isn't possible (e.g. inserting elements after
the root element of a <code>Document</code>).</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-insertAdjacentHTML"><code>insertAdjacentHTML(<var
title="">position</var>, <var title="">text</var>)</code></dfn>
method, when invoked, must run the following algorithm:</p>
<ol>
<li>
<p>Let <var title="">position</var> and <var title="">text</var>
be the method's first and second arguments, respectively.</p>
</li>
<li>
<p>Let <var title="">target</var> be the element on which the
method was invoked.</p>
</li>
<li>
<p>Use the first matching item from this list:</p>
<dl>
<dt>If <var title="">position</var> is an <span>ASCII
case-insensitive</span> match for the string "beforebegin"</dt>
<dt>If <var title="">position</var> is an <span>ASCII
case-insensitive</span> match for the string "afterend"</dt>
<dd>
<p>If <var title="">target</var> has no parent node, then abort
these steps.</p>
<p>If <var title="">target</var>'s parent node is a
<code>Document</code> object, then throw a
<code>NO_MODIFICATION_ALLOWED_ERR</code> exception and abort
these steps.
<p>Otherwise, let <var title="">context</var> be the parent node
of <var title="">target</var>.</p>
</dd>
<dt>If <var title="">position</var> is an <span>ASCII
case-insensitive</span> match for the string "afterbegin"</dt>
<dt>If <var title="">position</var> is an <span>ASCII
case-insensitive</span> match for the string "beforeend"</dt>
<dd>
<p>Let <var title="">context</var> be the same as <var
title="">target</var>.</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p>Throw a <code>SYNTAX_ERR</code> exception.</p>
</dd>
</dl>
</li>
<li>
<p>If <var title="">target</var>'s document is an <span
title="HTML documents">HTML document</span>: Invoke the <span>HTML
fragment parsing algorithm</span>.</p>
<p>If <var title="">target</var>'s document is an <span title="XML
documents">XML document</span>: Invoke the <span>XML fragment
parsing algorithm</span>.</p>
<p>In either case, the algorithm must be invoked with <var
title="">text</var> as the <var title="">input</var>, and the
element selected in by the previous step as the <var
title="">context</var> element.</p>
<p>If this raises an exception, then abort these steps.</p>
<p>Otherwise, let <var title="">new children</var> be the nodes
returned.</p>
</li>
<li>
<p>Set the <code title="">ownerDocument</code> of all the nodes in
<var title="">new children</var> to <var title="">target</var>'s
document.</p>
</li>
<li>
<p>Use the first matching item from this list:</p>
<dl>
<dt>If <var title="">position</var> is an <span>ASCII
case-insensitive</span> match for the string "beforebegin"</dt>
<dd>
<p>Insert all the <var title="">new children</var> nodes
immediately before <var title="">target</var>.</p>
</dd>
<dt>If <var title="">position</var> is an <span>ASCII
case-insensitive</span> match for the string "afterbegin"</dt>
<dd>
<p>Insert all the <var title="">new children</var> nodes before
the first child of <var title="">target</var>, if there is
one. If there is no such child, append them all to <var
title="">target</var>.</p>
</dd>
<dt>If <var title="">position</var> is an <span>ASCII
case-insensitive</span> match for the string "beforeend"</dt>
<dd>
<p>Append all the <var title="">new children</var> nodes to <var
title="">target</var>.</p>
</dd>
<dt>If <var title="">position</var> is an <span>ASCII
case-insensitive</span> match for the string "afterend"</dt>
<dd>
<p>Insert all the <var title="">new children</var> nodes
immediately after <var title="">target</var>.</p>
</dd>
</dl>
<p>The <var title="">new children</var> nodes must be inserted in
a manner that preserves their order and fires mutation events as
if a <code>DocumentFragment</code> containing the <var
title="">new children</var> had been inserted.</p>
</li>
</ol>
</div>
<h2 id="semantics">The elements of HTML</h2>
<h3>The root element</h3>
<h4>The <dfn><code>html</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As the root element of a document.</dd>
<dd>Wherever a subdocument fragment is allowed in a compound document.</dd>
<dt>Content model:</dt>
<dd>A <code>head</code> element followed by a <code>body</code> element.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-html-manifest">manifest</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLHtmlElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>html</code> element <span>represents</span> the root of
an HTML document.</p>
<p>The <dfn title="attr-html-manifest"><code>manifest</code></dfn>
attribute gives the address of the document's <span>application
cache</span> <span
title="concept-appcache-manifest">manifest</span>, if there is
one. If the attribute is present, the attribute's value must be a
<span>valid URL</span>.</p>
<p>The <code title="attr-html-manifest">manifest</code> attribute
only <span title="concept-appcache-init">has an effect</span> during
the early stages of document load. Changing the attribute
dynamically thus has no effect (and thus, no DOM API is provided for
this attribute).</p>
<p class="note">For the purposes of <span
title="concept-appcache-init">application cache selection</span>,
later <code>base</code> elements cannot affect the <span
title="resolve a url">resolving of relative URLs</span> in <code
title="attr-html-manifest">manifest</code> attributes, as the
attributes are processed before those elements are seen.</p>
<div class="example">
<p>The <code>html</code> element in the following example declares
that the document's language is English.</p>
<pre><!DOCTYPE html>
<strong><html lang="en"></strong>
<head>
<title>Swapping Songs</title>
</head>
<body>
<h1>Swapping Songs</h1>
<p>Tonight I swapped some of the songs I wrote with some friends, who
gave me some of the songs they wrote. I love sharing my music.</p>
</body>
<strong></html></strong></pre>
</div>
<h3>Document metadata</h3>
<h4>The <dfn><code>head</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As the first element in an <code>html</code> element.</dd>
<dt>Content model:</dt>
<dd>One or more elements of <span>metadata content</span>, of which exactly one is a <code>title</code> element.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLHeadElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>head</code> element <span>represents</span> a
collection of metadata for the <code>Document</code>.</p>
<div class="example">
<p>The collection of metadata in a <code>head</code> element can be
large or small. Here is an example of a very short one:</p>
<pre><!doctype html>
<html>
<head>
<title>A document with a short head</title>
</head>
<body>
...</pre>
<p>Here is an example of a longer one:</p>
<pre><!DOCTYPE HTML>
<HTML>
<HEAD>
<META CHARSET="UTF-8">
<BASE HREF="http://www.example.com/">
<TITLE>An application with a long head</TITLE>
<LINK REL="STYLESHEET" HREF="default.css">
<LINK REL="STYLESHEET ALTERNATE" HREF="big.css" TITLE="Big Text">
<SCRIPT SRC="support.js"></SCRIPT>
<META NAME="APPLICATION-NAME" CONTENT="Long headed application">
</HEAD>
<BODY>
...</pre>
</div>
<h4>The <dfn><code>title</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Metadata content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>In a <code>head</code> element containing no other <code>title</code> elements.</dd>
<dt>Content model:</dt>
<dd><span title="text content">Text</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTitleElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-title-text">text</span>;
};</pre>
</dd>
</dl>
<p>The <code>title</code> element <span>represents</span> the
document's title or name. Authors should use titles that identify
their documents even when they are used out of context, for example
in a user's history or bookmarks, or in search results. The
document's title is often different from its first heading, since the
first heading does not have to stand alone when taken out of
context.</p>
<p>There must be no more than one <code>title</code> element per
document.</p>
<dl class="domintro">
<dt><var title="">title</var> . <code title="dom-title-text">text</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the contents of the element, ignoring child nodes that
aren't <span title="text node">text nodes</span>.</p>
<p>Can be set, to replace the element's children with the given
value.</p>
</dd>
</dl>
<div class="impl">
<p>The IDL attribute <dfn
title="dom-title-text"><code>text</code></dfn> must return a
concatenation of the contents of all the <span title="text
node">text nodes</span> that are direct children of the
<code>title</code> element (ignoring any other nodes such as
comments or elements), in tree order. On setting, it must act the
same way as the <code>textContent</code> IDL attribute.</p>
</div>
<div class="example">
<p>Here are some examples of appropriate titles, contrasted with
the top-level headings that might be used on those same pages.</p>
<pre> <title>Introduction to The Mating Rituals of Bees</title>
...
<h1>Introduction</h1>
<p>This companion guide to the highly successful
<cite>Introduction to Medieval Bee-Keeping</cite> book is...</pre>
<p>The next page might be a part of the same site. Note how the
title describes the subject matter unambiguously, while the first
heading assumes the reader knows what the context is and therefore
won't wonder if the dances are Salsa or Waltz:</p>
<pre> <title>Dances used during bee mating rituals</title>
...
<h1>The Dances</h1></pre>
</div>
<p>The string to use as the document's title is given by the <code
title="dom-document-title">document.title</code> IDL
attribute. <span class="impl">User agents should use the document's
title when referring to the document in their user
interface.</span></p>
<h4>The <dfn><code>base</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Metadata content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>In a <code>head</code> element containing no other <code>base</code> elements.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-base-href">href</code></dd>
<dd><code title="attr-base-target">target</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLBaseElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-base-href">href</span>;
attribute DOMString <span title="dom-base-target">target</span>;
};</pre>
</dd>
</dl>
<p>The <code>base</code> element allows authors to specify the
<span>document base URL</span> for the purposes of <span
title="resolve a url">resolving relative URLs</span>, and the name
of the default <span>browsing context</span> for the purposes of
<span>following hyperlinks</span>. The element does not <span
title="represents">represent</span> any content beyond this
information.</p>
<p>There must be no more than one <code>base</code> element per
document.</p>
<p>A <code>base</code> element must have either an <code
title="attr-base-href">href</code> attribute, a <code
title="attr-base-target">target</code> attribute, or both.</p>
<p>The <dfn title="attr-base-href"><code>href</code></dfn> content
attribute, if specified, must contain a <span>valid URL</span>.</p>
<p>A <code>base</code> element, if it has an <code
title="attr-base-href">href</code> attribute, must come before any
other elements in the tree that have attributes defined as taking
<span title="URL">URLs</span>, except the <code>html</code> element
(its <code title="attr-html-manifest">manifest</code> attribute
isn't affected by <code>base</code> elements).</p>
<div class="impl">
<p class="note">If there are multiple <code>base</code> elements
with <code title="attr-base-href">href</code> attributes, all but the
first are ignored.</p>
</div>
<p>The <dfn title="attr-base-target"><code>target</code></dfn>
attribute, if specified, must contain a <span>valid browsing context
name or keyword</span>, which specifies which <span>browsing
context</span> is to be used as the default when <span
title="hyperlink">hyperlinks</span> and <span
title="form">forms</span> in the <code>Document</code> cause <span
title="navigate">navigation</span>.</p>
<p>A <code>base</code> element, if it has a <code
title="attr-base-target">target</code> attribute, must come before
any elements in the tree that represent <span
title="hyperlink">hyperlinks</span>.</p>
<div class="impl">
<p class="note">If there are multiple <code>base</code> elements
with <code title="attr-base-target">target</code> attributes, all but
the first are ignored.</p>
<p>The <dfn title="dom-base-href"><code>href</code></dfn> and <dfn
title="dom-base-target"><code>target</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name.</p>
</div>
<div class="example">
<p>In this example, a <code>base</code> element is used to set the
<span>document base URL</span>:</p>
<pre><!DOCTYPE html>
<html>
<head>
<title>This is an example for the &lt;base&gt; element</title>
<base href="http://www.example.com/news/index.html">
</head>
<body>
<p>Visit the <a href="archives.html">archives</a>.</p>
</body>
</html></pre>
<p>The link in the above example would be a link to "<code
title="">http://www.example.com/news/archives.html</code>".</p>
</div>
<h4>The <dfn><code>link</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Metadata content</span>.</dd>
<dd>If the <code title="attr-itemprop">itemprop</code> attribute is present: <span>flow content</span>.</dd>
<dd>If the <code title="attr-itemprop">itemprop</code> attribute is present: <span>phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>metadata content</span> is expected.</dd>
<dd>In a <code>noscript</code> element that is a child of a <code>head</code> element.</dd>
<dd>If the <code title="attr-itemprop">itemprop</code> attribute is present: where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-link-href">href</code></dd>
<dd><code title="attr-link-rel">rel</code></dd>
<dd><code title="attr-link-media">media</code></dd>
<dd><code title="attr-link-hreflang">hreflang</code></dd>
<dd><code title="attr-link-type">type</code></dd>
<dd><code title="attr-link-sizes">sizes</code></dd>
<dd>Also, the <code title="attr-link-title">title</code> attribute has special semantics on this element.</dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLLinkElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-link-disabled">disabled</span>;
attribute DOMString <span title="dom-link-href">href</span>;
attribute DOMString <span title="dom-link-rel">rel</span>;
readonly attribute DOMTokenList <span title="dom-link-relList">relList</span>;
attribute DOMString <span title="dom-link-media">media</span>;
attribute DOMString <span title="dom-link-hreflang">hreflang</span>;
attribute DOMString <span title="dom-link-type">type</span>;
attribute DOMString <span title="dom-link-sizes">sizes</span>;
};
<span>HTMLLinkElement</span> implements <span>LinkStyle</span>;</pre>
</dd>
</dl>
<p>The <code>link</code> element allows authors to link their
document to other resources.</p>
<p>The destination of the link(s) is given by the <dfn
title="attr-link-href"><code>href</code></dfn> attribute, which must
be present and must contain a <span>valid URL</span>. <span
class="impl">If the <code title="attr-link-href">href</code>
attribute is absent, then the element does not define a
link.</span></p>
<p>The types of link indicated (the relationships) are given by the
value of the <dfn title="attr-link-rel"><code>rel</code></dfn>
attribute, which must be present, and must have a value that is a
<span>set of space-separated tokens</span>. The <a
href="#linkTypes">allowed values and their meanings</a> are defined
in a later section. <span class="impl">If the <code
title="attr-link-rel">rel</code> attribute is absent, or if the
values used are not allowed according to the definitions in this
specification, then the element does not define a link.</span></p>
<p>Two categories of links can be created using the
<code>link</code> element. <dfn title="external resource link">Links
to external resources</dfn> are links to resources that are to be
used to augment the current document, and <dfn title="hyperlink
link">hyperlink links</dfn> are <span title="hyperlink">links to
other documents</span>. The <a href="#linkTypes">link types
section</a> defines whether a particular link type is an external
resource or a hyperlink. One element can create multiple links (of
which some might be external resource links and some might be
hyperlinks); exactly which and how many links are created depends on
the keywords given in the <code title="attr-link-rel">rel</code>
attribute. User agents must process the links on a per-link basis,
not a per-element basis.</p>
<p class="note">Each link is handled separately. For instance, if
there are two <code>link</code> elements with <code
title="">rel="stylesheet"</code>, they each count as a separate
external resource, and each is affected by its own attributes
independently.</p>
<p>The exact behavior for links to external resources depends on the
exact relationship, as defined for the relevant link type. Some of
the attributes control whether or not the external resource is to be
applied (as defined below). <span class="impl">For external
resources that are represented in the DOM (for example, style
sheets), the DOM representation must be made available even if the
resource is not applied. To <dfn title="concept-link-obtain">obtain
the resource</dfn>, the user agent must <span title="resolve a
url">resolve</span> the <span>URL</span> given by the <code
title="attr-link-href">href</code> attribute, relative to the
element, and then <span>fetch</span> the resulting <span>absolute
URL</span>. User agents may opt to only try to obtain such resources
when they are needed, instead of pro-actively <span
title="fetch">fetching</span> all the external resources that are
not applied.</span></p> <!-- http-origin privacy sensitive -->
<div class="impl">
<p>The semantics of the protocol used (e.g. HTTP) must be followed
when fetching external resources. (For example, redirects will be
followed and 404 responses will cause the external resource to not
be applied.)</p>
<!-- the next few paragraph are similar to text in the <style> section -->
<p>Once the attempts to obtain the resource and its critical
subresources are complete, the user agent must, if the loads were
successful, <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-load">load</code> at the
<code>link</code> element, or, if the resource or one of its
critical subresources failed to completely load for any reason
(e.g. DNS error, HTTP 404 response, a connection being prematurely
closed, unsupported Content-Type), <span>queue a task</span> to
<span>fire a simple event</span> named <code
title="event-error">error</code> at the <code>link</code>
element. Non-network errors in processing the resource or its
subresources (e.g. CSS parse errors, PNG decoding errors) are not
failures for the purposes of this paragraph.</p>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <span>DOM manipulation
task source</span>.</p>
<p>The element must <span>delay the load event</span> of the
element's document until all the attempts to obtain the resource and
its critical subresources are complete. (Resources that the user
agent has not yet attempted to obtain, e.g. because it is waiting
for the resource to be needed, do not <span>delay the load
event</span>.)</p>
<p>Which resources are considered critical or not is defined by the
relevant specification. For CSS resources, only <code
title="">@import</code> rules introduce critical subresources; other
resources, e.g. fonts or backgrounds, are not.</p>
<hr>
<p id="linkui">Interactive user agents may provide users with a
means to <span title="following hyperlinks">follow the
hyperlinks</span> created using the <code>link</code> element,
somewhere within their user interface. The exact interface is not
defined by this specification, but it could include the following
information (obtained from the element's attributes, again as
defined below), in some form or another (possibly simplified), for
each hyperlink created with each <code>link</code> element in the
document:</p>
<ul> <!-- the order here is the order that makes most sense for a UI -->
<li>The relationship between this document and the resource (given
by the <code title="attr-link-rel">rel</code> attribute)</li>
<li>The title of the resource (given by the <code
title="attr-link-title">title</code> attribute).</li>
<li>The address of the resource (given by the <code
title="attr-link-href">href</code> attribute).</li>
<li>The language of the resource (given by the <code
title="attr-link-hreflang">hreflang</code> attribute).</li>
<li>The optimum media for the resource (given by the <code
title="attr-link-media">media</code> attribute).</li>
</ul>
<p>User agents could also include other information, such as the
type of the resource (as given by the <code
title="attr-link-type">type</code> attribute).</p>
</div>
<p class="note">Hyperlinks created with the <code>link</code>
element and its <code title="attr-link-rel">rel</code> attribute
apply to the whole page. This contrasts with the <code
title="attr-hyperlink-rel">rel</code> attribute of <code>a</code>
and <code>area</code> elements, which indicates the type of a link
whose context is given by the link's location within the
document.</p>
<p>The <dfn title="attr-link-media"><code>media</code></dfn>
attribute says which media the resource applies to. The value must
be a <span>valid media query</span>.</p>
<div class="impl">
<p>If the link is a <span title="hyperlink link">hyperlink</span>
then the <code title="attr-link-media">media</code> attribute is
purely advisory, and describes for which media the document in
question was designed.</p>
<p>However, if the link is an <span>external resource link</span>,
then the <code title="attr-link-media">media</code> attribute is
prescriptive. The user agent must apply the external resource to a
<span>view</span> when the <code
title="attr-link-media">media</code> attribute's value <span>matches
the environment</span> of that view and the other relevant
conditions apply, and must not apply it otherwise.</p><!-- note
similar text in <style> section -->
<p class="note">The external resource might have further
restrictions defined within that limit its applicability. For
example, a CSS style sheet might have some <code
title="">@media</code> blocks. This specification does not override
such further restrictions or requirements.</p><!-- note similar text
in <style> section -->
</div>
<p id="default-media">The default, if the <code
title="attr-link-media">media</code> attribute is omitted, is "<code
title="">all</code>", meaning that by default links apply to all
media.</p>
<p>The <dfn title="attr-link-hreflang"><code>hreflang</code></dfn>
attribute on the <code>link</code> element has the same semantics as
the <span title="attr-hyperlink-hreflang"><code>hreflang</code>
attribute on hyperlink elements</span>.</p>
<p>The <dfn title="attr-link-type"><code>type</code></dfn> attribute
gives the <span>MIME type</span> of the linked resource. It is
purely advisory. The value must be a <span>valid MIME type</span>,
optionally with parameters.</p>
<p>For <span title="external resource link">external resource
links</span>, the <code title="attr-link-type">type</code> attribute
is used as a hint to user agents so that they can avoid fetching
resources they do not support. <span class="impl">If the attribute
is present, then the user agent must assume that the resource is of
the given type (even if that is not a <span>valid MIME type</span>,
e.g. the empty string). If the attribute is omitted, but the
external resource link type has a default type defined, then the
user agent must assume that the resource is of that type. If the UA
does not support the given <span>MIME type</span> for the given link
relationship, then the UA should not <span
title="concept-link-obtain">obtain</span> the resource; if the UA
does support the given <span>MIME type</span> for the given link
relationship, then the UA should <span
title="concept-link-obtain">obtain</span> the resource. If the
attribute is omitted, and the external resource link type does not
have a default type defined, but the user agent would <span
title="concept-link-obtain">obtain</span> the resource if the type
was known and supported, then the user agent should <span
title="concept-link-obtain">obtain</span> the resource under the
assumption that it will be supported.</span></p>
<div class="impl">
<p>User agents must not consider the <code
title="attr-link-type">type</code> attribute authoritative —
upon fetching the resource, user agents must not use the <code
title="attr-link-type">type</code> attribute to determine its actual
type. Only the actual type (as defined in the next paragraph) is
used to determine whether to <em>apply</em> the resource, not the
aforementioned assumed type.</p>
<p id="concept-link-type-sniffing">If the external resource link
type defines rules for processing the resource's <span
title="Content-Type">Content-Type metadata</span>, then those rules
apply. Otherwise, if the resource is expected to be an image, user
agents may apply the <span title="Content-Type sniffing:
image">image sniffing rules</span>, with the <var title="">official
type</var> being the type determined from the resource's <span
title="Content-Type">Content-Type metadata</span>, and use the
resulting sniffed type of the resource as if it was the actual
type. Otherwise, if neither of these conditions apply or if the user
agent opts not to apply the image sniffing rules, then the user
agent must use the resource's <span
title="Content-Type">Content-Type metadata</span> to determine the
type of the resource. If there is no type metadata, but the external
resource link type has a default type defined, then the user agent
must assume that the resource is of that type.</p>
<p class="note">The <code title="rel-stylesheet">stylesheet</code>
link type defines rules for processing the resource's <span
title="Content-Type">Content-Type metadata</span>.</p>
<p>Once the user agent has established the type of the resource, the
user agent must apply the resource if it is of a supported type and
the other relevant conditions apply, and must ignore the resource
otherwise.</p>
<div class="example">
<p>If a document contains style sheet links labeled as follows:</p>
<pre><link rel="stylesheet" href="A" type="text/plain">
<link rel="stylesheet" href="B" type="text/css">
<link rel="stylesheet" href="C"></pre>
<p>...then a compliant UA that supported only CSS style sheets
would fetch the B and C files, and skip the A file (since
<code>text/plain</code> is not the <span>MIME type</span> for CSS style
sheets).</p>
<p>For files B and C, it would then check the actual types returned
by the server. For those that are sent as <code>text/css</code>, it
would apply the styles, but for those labeled as
<code>text/plain</code>, or any other type, it would not.</p>
<p>If one of the two files was returned without a
<span>Content-Type</span> metadata, or with a syntactically
incorrect type like <code
title="">Content-Type: "null"</code>, then the default type
for <code title="rel-stylesheet">stylesheet</code> links would kick
in. Since that default type is <code title="">text/css</code>, the
style sheet <em>would</em> nonetheless be applied.</p>
</div>
</div>
<p>The <dfn title="attr-link-title"><code>title</code></dfn>
attribute gives the title of the link. With one exception, it is
purely advisory. The value is text. The exception is for style sheet
links, where the <code title="attr-link-title">title</code>
attribute defines <span>alternative style sheet sets</span>.</p>
<p class="note">The <code title="attr-link-title">title</code>
attribute on <code>link</code> elements differs from the global
<code title="attr-title">title</code> attribute of most other
elements in that a link without a title does not inherit the title
of the parent element: it merely has no title.</p>
<p>The <code title="attr-link-sizes">sizes</code> attribute is used
with the <code title="rel-icon">icon</code> link type. The attribute
must not be specified on <code>link</code> elements that do not have
a <code title="attr-link-rel">rel</code> attribute that specifies
the <code title="rel-icon">icon</code> keyword.</p>
<div class="impl">
<p>Some versions of HTTP defined a <code title="">Link:</code>
header, to be processed like a series of <code>link</code> elements.
If supported, for the purposes of ordering links defined by HTTP
headers must be assumed to come before any links in the document, in
the order that they were given in the HTTP entity header. (URIs in
these headers are to be processed and resolved according to the
rules given in HTTP; the rules of <em>this</em> specification don't
apply.) <a href="#refsHTTP">[HTTP]</a> <a
href="#refsWEBLINK">[WEBLINK]</a></p> <!-- WEBLINK is ref for Link: header -->
<p>The IDL attributes <dfn
title="dom-link-href"><code>href</code></dfn>, <dfn
title="dom-link-rel"><code>rel</code></dfn>, <dfn
title="dom-link-media"><code>media</code></dfn>, <dfn
title="dom-link-hreflang"><code>hreflang</code></dfn>, and <dfn
title="dom-link-type"><code>type</code></dfn>, and <dfn
title="dom-link-sizes"><code>sizes</code></dfn> each must
<span>reflect</span> the respective content attributes of the same
name.</p>
<p>The IDL attribute <dfn
title="dom-link-rellist"><code>relList</code></dfn> <span
class="impl">must</span> <span title="reflect">reflect</span> the <code
title="attr-link-rel">rel</code> content attribute.</p>
</div>
<p>The IDL attribute <dfn
title="dom-link-disabled"><code>disabled</code></dfn> only applies
to style sheet links. When the <code>link</code> element defines a
style sheet link, then the <code
title="dom-link-disabled">disabled</code> attribute behaves as
defined <span title="dom-linkstyle-disabled">for the alternative
style sheets DOM</span>. For all other <code>link</code> elements it
always return false and does nothing on setting.</p> <!-- that is
normatively required in the definition of dom-linkstyle-disabled -->
<p>The <code>LinkStyle</code> interface is also implemented by
this element; the <span>styling processing model</span> defines
how. <a href="#refsCSSOM">[CSSOM]</a></p>
<div class="example">
<p>Here, a set of <code>link</code> elements provide some style
sheets:</p>
<pre><!-- a persistent style sheet -->
<link rel="stylesheet" href="default.css">
<!-- the preferred alternate style sheet -->
<link rel="stylesheet" href="green.css" title="Green styles">
<!-- some alternate style sheets -->
<link rel="alternate stylesheet" href="contrast.css" title="High contrast">
<link rel="alternate stylesheet" href="big.css" title="Big fonts">
<link rel="alternate stylesheet" href="wide.css" title="Wide screen"></pre>
</div>
<div class="example">
<p>The following example shows how you can specify versions of the
page that use alternative formats, are aimed at other languages,
and that are intended for other media:</p>
<pre><link rel=alternate href="/en/html" hreflang=en type=text/html title="English HTML">
<link rel=alternate href="/fr/html" hreflang=fr type=text/html title="French HTML">
<link rel=alternate href="/en/html/print" hreflang=en type=text/html media=print title="English HTML (for printing)">
<link rel=alternate href="/fr/html/print" hreflang=fr type=text/html media=print title="French HTML (for printing)">
<link rel=alternate href="/en/pdf" hreflang=en type=application/pdf title="English PDF">
<link rel=alternate href="/fr/pdf" hreflang=fr type=application/pdf title="French PDF"></pre>
</div>
<h4 id="meta">The <dfn><code>meta</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Metadata content</span>.</dd>
<dd>If the <code title="attr-itemprop">itemprop</code> attribute is present: <span>flow content</span>.</dd>
<dd>If the <code title="attr-itemprop">itemprop</code> attribute is present: <span>phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>If the <code title="attr-meta-charset">charset</code> attribute is present, or if the element's <code title="attr-meta-http-equiv">http-equiv</code> attribute is in the <span title="attr-meta-http-equiv-content-type">Encoding declaration state</span>: in a <code>head</code> element.</dd>
<dd>If the <code title="attr-meta-http-equiv">http-equiv</code> attribute is present but not in the <span title="attr-meta-http-equiv-content-type">Encoding declaration state</span>: in a <code>head</code> element.</dd>
<dd>If the <code title="attr-meta-http-equiv">http-equiv</code> attribute is present but not in the <span title="attr-meta-http-equiv-content-type">Encoding declaration state</span>: in a <code>noscript</code> element that is a child of a <code>head</code> element.</dd>
<dd>If the <code title="attr-meta-name">name</code> attribute is present: where <span>metadata content</span> is expected.</dd>
<dd>If the <code title="attr-itemprop">itemprop</code> attribute is present: where <span>metadata content</span> is expected.</dd>
<dd>If the <code title="attr-itemprop">itemprop</code> attribute is present: where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-meta-name">name</code></dd>
<dd><code title="attr-meta-http-equiv">http-equiv</code></dd>
<dd><code title="attr-meta-content">content</code></dd>
<dd><code title="attr-meta-charset">charset</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLMetaElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-meta-name">name</span>;
attribute DOMString <span title="dom-meta-httpEquiv">httpEquiv</span>;
attribute DOMString <span title="dom-meta-content">content</span>;
};</pre>
</dd>
</dl>
<p>The <code>meta</code> element <span>represents</span> various
kinds of metadata that cannot be expressed using the
<code>title</code>, <code>base</code>, <code>link</code>,
<code>style</code>, and <code>script</code> elements.</p>
<p>The <code>meta</code> element can represent document-level
metadata with the <code title="attr-meta-name">name</code>
attribute, pragma directives with the <code
title="attr-meta-http-equiv">http-equiv</code> attribute, and the
file's <span>character encoding declaration</span> when an HTML
document is serialized to string form (e.g. for transmission over
the network or for disk storage) with the <code
title="attr-meta-charset">charset</code> attribute.</p>
<p>Exactly one of the <code title="attr-meta-name">name</code>,
<code title="attr-meta-http-equiv">http-equiv</code>, <code
title="attr-meta-charset">charset</code>, and <code
title="attr-itemprop">itemprop</code> attributes must be
specified.</p>
<p>If either <code title="attr-meta-name">name</code>, <code
title="attr-meta-http-equiv">http-equiv</code>, or <code
title="attr-itemprop">itemprop</code> is specified, then the <code
title="attr-meta-content">content</code> attribute must also be
specified. Otherwise, it must be omitted.</p>
<p>The <dfn title="attr-meta-charset"><code>charset</code></dfn>
attribute specifies the character encoding used by the
document. This is a <span>character encoding declaration</span>. If
the attribute is present in an <span title="XML documents">XML
document</span>, its value must be an <span>ASCII
case-insensitive</span> match for the string "<code
title="">UTF-8</code>" (and the document is therefore forced to use
UTF-8 as its encoding).</p>
<p class="note">The <code title="attr-meta-charset">charset</code>
attribute on the <code>meta</code> element has no effect in XML
documents, and is only allowed in order to facilitate migration to
and from XHTML.</p>
<p>There must not be more than one <code>meta</code> element with a
<code title="attr-meta-charset">charset</code> attribute per
document.</p>
<p>The <dfn title="attr-meta-content"><code>content</code></dfn>
attribute gives the value of the document metadata or pragma
directive when the element is used for those purposes. The allowed
values depend on the exact context, as described in subsequent
sections of this specification.</p>
<p>If a <code>meta</code> element has a <dfn
title="attr-meta-name"><code>name</code></dfn> attribute, it sets
document metadata. Document metadata is expressed in terms of
name/value pairs, the <code title="attr-meta-name">name</code>
attribute on the <code>meta</code> element giving the name, and the
<code title="attr-meta-content">content</code> attribute on the same
element giving the value. The name specifies what aspect of metadata
is being set; valid names and the meaning of their values are
described in the following sections. If a <code>meta</code> element
has no <code title="attr-meta-content">content</code> attribute,
then the value part of the metadata name/value pair is the empty
string.</p>
<div class="impl">
<p>The <dfn title="dom-meta-name"><code>name</code></dfn> and <dfn
title="dom-meta-content"><code>content</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name. The IDL attribute <dfn
title="dom-meta-httpEquiv"><code>httpEquiv</code></dfn> must
<span>reflect</span> the content attribute <code
title="attr-meta-http-equiv">http-equiv</code>.</p>
</div>
<h5>Standard metadata names</h5>
<p>This specification defines a few names for the <code
title="attr-meta-name">name</code> attribute of the
<code>meta</code> element.</p>
<p>Names are case-insensitive<span class=impl>, and must be compared
in an <span>ASCII case-insensitive</span> manner</span>.</p>
<dl>
<dt><dfn title="meta-application-name"><code>application-name</code></dfn></dt>
<dd><p>The value must be a short free-form string giving the name
of the Web application that the page represents. If the page is not
a Web application, the <code
title="meta-application-name">application-name</code> metadata name
must not be used. There must not be more than one <code>meta</code>
element with its <code title="attr-meta-name">name</code> attribute
set to the value <code
title="meta-application-name">application-name</code> per
document. <span class="impl">User agents may use the application
name in UI in preference to the page's <code>title</code>, since
the title might include status messages and the like relevant to
the status of the page at a particular moment in time instead of
just being the name of the application.</span></p></dd>
<dt><dfn title="meta-author"><code>author</code></dfn></dt>
<dd><p>The value must be a free-form string giving the name of one
of the page's authors.</p></dd>
<dt><dfn title="meta-description"><code>description</code></dfn></dt>
<dd><p>The value must be a free-form string that describes the
page. The value must be appropriate for use in a directory of
pages, e.g. in a search engine. There must not be more than one
<code>meta</code> element with its <code
title="attr-meta-name">name</code> attribute set to the value <code
title="meta-description">description</code> per document.</p></dd>
<dt><dfn title="meta-generator"><code>generator</code></dfn></dt>
<dd>
<p>The value must be a free-form string that identifies one of the
software packages used to generate the document. This value must
not be used on hand-authored pages.</p>
<div class="example">
<p>Here is what a tool called "Frontweaver" could include in its
output, in the page's <code>head</code> element, to identify
itself as the tool used to generate the page:</p>
<pre><meta name=generator content="Frontweaver 8.2"></pre>
</div>
</dd>
</dl>
<h5>Other metadata names</h5>
<p><dfn title="concept-meta-extensions">Extensions to the predefined
set of metadata names</dfn> may be registered in the <a
href="http://wiki.whatwg.org/wiki/MetaExtensions">WHATWG Wiki
MetaExtensions page</a>. <a href="#refsWHATWGWIKI">[WHATWGWIKI]</a></p>
<p>Anyone is free to edit the WHATWG Wiki MetaExtensions page at any
time to add a type. These new names must be specified with the
following information:</p>
<dl>
<dt>Keyword</dt>
<dd><p>The actual name being defined. The name should not be
confusingly similar to any other defined name (e.g. differing only
in case).</p></dd>
<dt>Brief description</dt>
<dd><p>A short non-normative description of what the metadata
name's meaning is, including the format the value is required to be
in.</p></dd>
<dt>Specification</dt>
<dd>A link to a more detailed description of the metadata name's
semantics and requirements. It could be another page on the Wiki,
or a link to an external page.</dd>
<dt>Synonyms</dt>
<dd><p>A list of other names that have exactly the same processing
requirements. Authors should not use the names defined to be
synonyms, they are only intended to allow user agents to support
legacy content. Anyone may remove synonyms that are not used in
practice; only names that need to be processed as synonyms for
compatibility with legacy content are to be registered in this
way.</p></dd>
<dt>Status</dt>
<dd>
<p>One of the following:</p>
<dl>
<dt>Proposed</dt>
<dd>The name has not received wide peer review and
approval. Someone has proposed it and is, or soon will be, using
it.</dd>
<dt>Ratified</dt>
<dd>The name has received wide peer review and approval. It has a
specification that unambiguously defines how to handle pages that
use the name, including when they use it in incorrect ways.</dd>
<dt>Discontinued</dt>
<dd>The metadata name has received wide peer review and it has
been found wanting. Existing pages are using this metadata name,
but new pages should avoid it. The "brief description" and
"specification" entries will give details of what authors should
use instead, if anything.</dd>
</dl>
<p>If a metadata name is found to be redundant with existing
values, it should be removed and listed as a synonym for the
existing value.</p>
<p>If a metadata name is registered in the "proposed" state for a
period of a month or more without being used or specified, then it
may be removed from the registry.</p>
<p>If a metadata name is added with the "proposed" status and
found to be redundant with existing values, it should be removed
and listed as a synonym for the existing value. If a metadata name
is added with the "proposed" status and found to be harmful, then
it should be changed to "discontinued" status.</p>
<p>Anyone can change the status at any time, but should only do so
in accordance with the definitions above.</p>
</dd>
</dl>
<div class="impl">
<p>Conformance checkers must use the information given on the WHATWG
Wiki MetaExtensions page to establish if a value is allowed or not:
values defined in this specification or marked as "proposed" or
"ratified" must be accepted, whereas values marked as "discontinued"
or not listed in either this specification or on the aforementioned
page must be rejected as invalid. Conformance checkers may cache
this information (e.g. for performance reasons or to avoid the use
of unreliable network connectivity).</p>
<p>When an author uses a new metadata name not defined by either
this specification or the Wiki page, conformance checkers should
offer to add the value to the Wiki, with the details described
above, with the "proposed" status.</p>
</div>
<p>Metadata names whose values are to be <span
title="URL">URLs</span> must not be proposed or accepted. Links must
be represented using the <code>link</code> element, not the
<code>meta</code> element.</p>
<h5>Pragma directives</h5>
<p>When the <dfn
title="attr-meta-http-equiv"><code>http-equiv</code></dfn> attribute
is specified on a <code>meta</code> element, the element is a pragma
directive.</p>
<p>The <code title="attr-meta-http-equiv">http-equiv</code>
attribute is an <span>enumerated attribute</span>. The following
table lists the keywords defined for this attribute. The states
given in the first cell of the rows with keywords give the states to
which those keywords map. <!--<span class="impl">Some of the
keywords are non-conforming, as noted in the last
column.</span>--></p>
<!-- things that are neither conforming nor do anything are commented out -->
<!-- if you add something non-conforming, uncomment out the last sentence above -->
<table>
<thead>
<tr>
<th>State
<th>Keywords
<th>Notes
<tbody>
<tr>
<td><span title="attr-meta-http-equiv-content-language">Content Language</span>
<td><code title="">content-language</code>
<td>Conformance checkers will include a warning
<tr>
<td><span title="attr-meta-http-equiv-content-type">Encoding declaration</span>
<td><code title="">content-type</code>
<td>
<!--
<tr class="impl">
<td><span title="attr-meta-http-equiv-content-script-type">Content-Script-Type</span>
<td><code title="">Content-Script-Type</code>
<td>Non-conforming
<tr class="impl">
<td><span title="attr-meta-http-equiv-content-style-type">Content-Style-Type</span>
<td><code title="">Content-Style-Type</code>
<td>Non-conforming
-->
<tr>
<td><span title="attr-meta-http-equiv-default-style">Default style</span>
<td><code title="">default-style</code>
<td>
<tr>
<td><span title="attr-meta-http-equiv-refresh">Refresh</span>
<td><code title="">refresh</code>
<td>
</table>
<!--
DATA: According to Henri's validator stats, here are common
non-conforming values used by people who validate (sample of 400
pages):
COUNT ERROR
20 Bad value "Content-Language" for attribute "http-equiv" on element "meta".
17 Bad value "Content-Style-Type" for attribute "http-equiv" on element "meta".
12 Bad value "Expires" for attribute "http-equiv" on element "meta".
11 Bad value "Pragma" for attribute "http-equiv" on element "meta".
11 Bad value "imagetoolbar" for attribute "http-equiv" on element "meta".
10 Bad value "Content-Script-Type" for attribute "http-equiv" on element "meta".
10 Bad value "content-language" for attribute "http-equiv" on element "meta".
[...]
http://hsivonen.iki.fi/test/moz/analysis.txt
Here's some more data, this time from Philip`, on a sample of 15k pages.
COUNT VALUE
1181 Content-Language
430 Content-Style-Type
342 imagetoolbar
276 content-language
269 Pragma
260 expires
227 Expires
211 pragma
146 Content-Script-Type
132 keywords
119 Page-Enter
116 description
106 reply-to
102 Cache-Control
[...]
http://philip.html5.org/data/meta-http-equiv.txt
These numbers are low; further study is required to establish what
people expect to have work and what is necessary.
-->
<div class="impl">
<p>When a <code>meta</code> element is <span title="insert an
element into a document">inserted into the document</span>, if its
<code title="attr-meta-http-equiv">http-equiv</code> attribute is
present and represents one of the above states, then the user agent
must run the algorithm appropriate for that state, as described in
the following list:</p>
</div>
<dl>
<dt><dfn title="attr-meta-http-equiv-content-language">Content language state</dfn> (<code title="">http-equiv="content-language"</code>)
<dd>
<p>This pragma sets the <dfn>document-wide default
language</dfn>. Until the pragma is successfully processed, there
is no <span>document-wide default language</span>.</p>
<p class="note">Conformance checkers will include a warning if
this pragma is used. Authors are encouraged to use the <code
title="attr-lang">lang</code> attribute instead.</p>
<div class="impl">
<ol>
<li><p>If another <code>meta</code> element with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-content-language">Content
Language state</span> has already been successfully processed
(i.e. when it was inserted the user agent processed it and
reached the last step of this list of steps), then abort these
steps.</p></li>
<li><p>If the <code>meta</code> element has no <code
title="attr-meta-content">content</code> attribute, or if that
attribute's value is the empty string, then abort these
steps.</p></li>
<li><p>Let <var title="">input</var> be the value of the
element's <code title="attr-meta-content">content</code>
attribute.</p></li>
<li><p>Let <var title="">position</var> point at the first
character of <var title="">input</var>.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p><span title="collect a sequence of characters">Collect a
sequence of characters</span> that are neither <span title="space
character">space characters</span> nor a U+002C COMMA character
(,).</p></li>
<li><p>Let the <span>document-wide default language</span> be the
string that resulted from the previous step.</p></li>
</ol>
</div>
<p>For <code>meta</code> elements with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-content-language">Content
Language state</span>, the <code
title="attr-meta-content">content</code> attribute must have a
value consisting of a valid BCP 47 language code. <a
href="#refsBCP47">[BCP47]</a></p>
<p class="note">This pragma is not exactly equivalent to the HTTP
<code>Content-Language</code> header, for instance it only
supports one language. <a href="#refsHTTP">[HTTP]</a></p>
</dd>
<dt><dfn title="attr-meta-http-equiv-content-type">Encoding declaration state</dfn> (<code title="">http-equiv="content-type"</code>)
<dd>
<p>The <span title="attr-meta-http-equiv-content-type">Encoding
declaration state</span> is just an alternative form of setting
the <code title="meta-charset">charset</code> attribute: it is a
<span>character encoding declaration</span>. <span
class="impl">This state's user agent requirements are all handled
by the parsing section of the specification.</span></p>
<p>For <code>meta</code> elements with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-content-type">Encoding
declaration state</span>, the <code
title="attr-meta-content">content</code> attribute must have a
value that is an <span>ASCII case-insensitive</span> match for a
string that consists of: the literal string "<code
title="">text/html;</code>", optionally followed by any number of
<span title="space character">space characters</span>, followed by
the literal string "<code title="">charset=</code>", followed by
the character encoding name of the <span>character encoding
declaration</span>.</p>
<p>If the document contains a <code>meta</code> element with an
<code title="attr-meta-http-equiv">http-equiv</code> attribute in
the <span title="attr-meta-http-equiv-content-type">Encoding
declaration state</span>, then the document must not contain a
<code>meta</code> element with the <code
title="attr-meta-charset">charset</code> attribute present.</p>
<p>The <span title="attr-meta-http-equiv-content-type">Encoding
declaration state</span> may be used in <span>HTML
documents</span>, but elements with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in that
state must not be used in <span>XML documents</span>.</p>
</dd>
<dt><dfn title="attr-meta-http-equiv-default-style">Default style state</dfn> (<code title="">http-equiv="default-style"</code>)
<dd>
<p>This pragma sets the name of the default <span
title="alternative style sheet sets">alternative style sheet
set</span>.</p>
<div class="impl">
<ol>
<li><p>If the <code>meta</code> element has no <code
title="attr-meta-content">content</code> attribute, or if that
attribute's value is the empty string, then abort these
steps.</p></li>
<li><p>Set the <span>preferred style sheet set</span> to the
value of the element's <code
title="attr-meta-content">content</code> attribute. <a
href="#refsCSSOM">[CSSOM]</a></p></li>
</ol>
</div>
</dd>
<dt><dfn title="attr-meta-http-equiv-refresh">Refresh state</dfn> (<code title="">http-equiv="refresh"</code>)
<dd>
<p>This pragma acts as timed redirect.</p>
<div class="impl">
<ol>
<!-- TESTS: http://www.hixie.ch/tests/adhoc/html/meta/refresh/ -->
<li><p>If another <code>meta</code> element with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-refresh">Refresh state</span>
has already been successfully processed (i.e. when it was
inserted the user agent processed it and reached the last step of
this list of steps), then abort these steps.</p></li>
<li><p>If the <code>meta</code> element has no <code
title="attr-meta-content">content</code> attribute, or if that
attribute's value is the empty string, then abort these
steps.</p></li>
<li><p>Let <var title="">input</var> be the value of the
element's <code title="attr-meta-content">content</code>
attribute.</p></li>
<li><p>Let <var title="">position</var> point at the first
character of <var title="">input</var>.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p><span title="collect a sequence of characters">Collect a
sequence of characters</span> in the range U+0030 DIGIT ZERO (0)
to U+0039 DIGIT NINE (9), and parse the resulting string using
the <span>rules for parsing non-negative integers</span>. If the
sequence of characters collected is the empty string, then no
number will have been parsed; abort these steps. Otherwise, let
<var title="">time</var> be the parsed number.</p></li>
<li><p><span title="collect a sequence of characters">Collect a
sequence of characters</span> in the range U+0030 DIGIT ZERO (0) to
U+0039 DIGIT NINE (9) and U+002E FULL STOP (.). Ignore any collected
characters.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>Let <var title="">url</var> be the address of the current
page.</p></li>
<li><p>If the character in <var title="">input</var> pointed to
by <var title="">position</var> is a U+003B SEMICOLON ("<code
title="">;</code>"), then advance <var title="">position</var> to
the next character. Otherwise, jump to the last step.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>If the character in <var title="">input</var> pointed to
by <var title="">position</var> is a U+0055 LATIN CAPITAL LETTER
U character (U) or a U+0075 LATIN SMALL LETTER U character (u),
then advance <var title="">position</var> to the next
character. Otherwise, jump to the last step.</p></li>
<li><p>If the character in <var title="">input</var> pointed to
by <var title="">position</var> is a U+0052 LATIN CAPITAL LETTER
R character (R) or a U+0072 LATIN SMALL LETTER R character (r),
then advance <var title="">position</var> to the next
character. Otherwise, jump to the last step.</p></li>
<li><p>If the character in <var title="">input</var> pointed to
by <var title="">position</var> is s U+004C LATIN CAPITAL LETTER
L character (L) or a U+006C LATIN SMALL LETTER L character (l),
then advance <var title="">position</var> to the next
character. Otherwise, jump to the last step.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>If the character in <var title="">input</var> pointed to
by <var title="">position</var> is a U+003D EQUALS SIGN ("<code
title="">=</code>"), then advance <var title="">position</var> to
the next character. Otherwise, jump to the last step.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>If the character in <var title="">input</var> pointed to
by <var title="">position</var> is either a U+0027 APOSTROPHE
character (') or U+0022 QUOTATION MARK character ("), then let
<var title="">quote</var> be that character, and advance <var
title="">position</var> to the next character. Otherwise, let
<var title="">quote</var> be the empty string.</p></li>
<li><p>Let <var title="">url</var> be equal to the substring of
<var title="">input</var> from the character at <var
title="">position</var> to the end of the string.</p></li>
<li><p>If <var title="">quote</var> is not the empty string, and
there is a character in <var title="">url</var> equal to <var
title="">quote</var>, then truncate <var title="">url</var> at
that character, so that it and all subsequent characters are
removed.</p>
<li><p>Strip any trailing <span title="space character">space
characters</span> from the end of <var
title="">url</var>.</p></li>
<li><p>Strip any U+0009 CHARACTER TABULATION, U+000A LINE FEED
(LF), and U+000D CARRIAGE RETURN (CR) characters from <var
title="">url</var>.</p></li>
<li><p><span title="resolve a url">Resolve</span> the <var
title="">url</var> value to an <span>absolute URL</span>,
relative to the <code>meta</code> element. If this fails, abort
these steps.</p></li>
<li>
<p>Perform one or more of the following steps:</p>
<ul>
<li><p>Set a timer so that in <var title="">time</var> seconds,
adjusted to take into account user or user agent preferences,
if the user has not canceled the redirect, the user agent <span
title="navigate">navigates</span> the document's browsing
context to <var title="">url</var>, with <span>replacement
enabled</span>, and with the document's browsing context as the
<span>source browsing context</span>.</p></li>
<li><p>Provide the user with an interface that, when selected,
<span title="navigate">navigates</span> a <span>browsing
context</span> to <var title="">url</var>, with the document's
browsing context as the <span>source browsing
context</span>.</p></li>
<li><p>Do nothing.</p></li>
</ul>
<p>In addition, the user agent may, as with anything, inform the
user of any and all aspects of its operation, including the
state of any timers, the destinations of any timed redirects,
and so forth.</p>
</li>
</ol>
</div>
<p>For <code>meta</code> elements with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-refresh">Refresh state</span>,
the <code title="attr-meta-content">content</code> attribute must
have a value consisting either of:</p>
<ul>
<li> just a <span>valid non-negative integer</span>, or</li>
<li> a <span>valid non-negative integer</span>, followed by a
U+003B SEMICOLON character (;), followed by one or more <span
title="space character">space characters</span>, followed by
either a U+0055 LATIN CAPITAL LETTER U character (U) or a U+0075
LATIN SMALL LETTER U character (u), a U+0052 LATIN CAPITAL LETTER
R character (R) or a U+0072 LATIN SMALL LETTER R character (r), a
U+004C LATIN CAPITAL LETTER L character (L) or a U+006C LATIN
SMALL LETTER L character (l), a U+003D EQUALS SIGN character (=),
and then a <span>valid URL</span>.</li>
</ul>
<p>In the former case, the integer represents a number of seconds
before the page is to be reloaded; in the latter case the integer
represents a number of seconds before the page is to be replaced
by the page at the given <span>URL</span>.</p>
<div class="example">
<p>A news organization's front page could include the following
markup in the page's <code>head</code> element, to ensure that
the page automatically reloads from the server every five
minutes:</p>
<pre><meta http-equiv="Refresh" content="600"></pre>
</div>
<div class="example">
<p>A sequence of pages could be used as an automated slide show
by making each page refresh to the next page in the sequence,
using markup such as the following:</p>
<pre><meta http-equiv="Refresh" content="20; URL=page4.html"></pre>
</div>
</dd>
</dl>
<p>There must not be more than one <code>meta</code> element with
any particular state in the document at a time.</p>
<h5>Other pragma directives</h5>
<p><dfn title="concept-http-equiv-extensions">Extensions to the
predefined set of pragma directives</dfn> may, under certain
conditions, be registered in the <a
href="http://wiki.whatwg.org/wiki/PragmaExtensions">WHATWG Wiki
PragmaExtensions page</a>. <a
href="#refsWHATWGWIKI">[WHATWGWIKI]</a></p>
<p>Such extensions must use a name that is identical to an HTTP
header registered in the Permanent Message Header Field Registry,
and must have behavior identical to that described for the HTTP
header. <a href="#refsIANAPERMHEADERS">[IANAPERMHEADERS]</a></p>
<p>Pragma directives corresponding to headers describing metadata,
or not requiring specific user agent processing, must not be
registered; instead, use <span
title="concept-meta-extensions">metadata names</span>. Pragma
directives corresponding to headers that affect the HTTP processing
model (e.g. caching) must not be registered, as they would result in
HTTP-level behavior being different for user agents that implement
HTML than for user agents that do not.</p>
<p>Anyone is free to edit the WHATWG Wiki PragmaExtensions page at
any time to add a pragma directive satisfying these conditions. Such
registrations must specify the following information:</p>
<dl>
<dt>Keyword</dt>
<dd><p>The actual name being defined. The name must match a
previously-registered HTTP name with the same
requirements.</p></dd>
<dt>Brief description</dt>
<dd><p>A short non-normative description of the purpose of the
pragma directive.</p></dd>
<dt>Specification</dt>
<dd>A link to the specification defining the corresponding HTTP
header.</dd>
</dl>
<div class="impl">
<p>Conformance checkers must use the information given on the WHATWG
Wiki PragmaExtensions page to establish if a value is allowed or
not: values defined in this specification or listed on the
aforementioned page must be accepted, whereas values not listed in
either this specification or on the aforementioned page must be
rejected as invalid. Conformance checkers may cache this information
(e.g. for performance reasons or to avoid the use of unreliable
network connectivity).</p>
</div>
<h5 id="charset">Specifying the document's character encoding</h5>
<!-- READ ME WHEN EDITING: if we ever move this to the "writing
HTML" section, then we have to duplicate the requirements in the
parsing section for conformance checkers, and we have to make sure
that the requirements for charset="" apply even in XML, for the
<meta charset=""> polyglot hack. -->
<p>A <dfn>character encoding declaration</dfn> is a mechanism by
which the character encoding used to store or transmit a document is
specified.</p>
<p>The following restrictions apply to character encoding
declarations:</p>
<ul>
<li>The character encoding name given must be the name of the
character encoding used to serialize the file.</li>
<li>The value must be a valid character encoding name, and must be
an <span>ASCII case-insensitive</span> match for the
<span>preferred MIME name</span> for that encoding. <a
href="#refsIANACHARSET">[IANACHARSET]</a></li>
<li>The character encoding declaration must be serialized without
the use of <span title="syntax-charref">character references</span>
or character escapes of any kind.</li>
<li id="charset512">The element containing the character encoding
declaration must be serialized completely within the first 512
bytes of the document.</li>
<li>There can only be one character encoding declaration in the
document.</li> <!-- conformance criteria for this one are given in
the XML spec, the <meta> section just after defining charset="",
and the character encoding pragma section. And actually this
statement isn't quite true, since you can have an XML one and an
HTML one at the same time if they match. -->
</ul>
<p>If an <span title="HTML documents">HTML document</span> does not
start with a BOM, and if its encoding is not explicitly given by
<span title="Content-Type">Content-Type metadata</span>, then the
character encoding used must be an <span>ASCII-compatible character
encoding</span>, and, in addition, if that encoding isn't US-ASCII
itself, then the encoding must be specified using a
<code>meta</code> element with a <code
title="attr-meta-charset">charset</code> attribute or a
<code>meta</code> element with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-content-type">Encoding declaration
state</span>.</p>
<p>If an <span title="HTML documents">HTML document</span> contains
a <code>meta</code> element with a <code
title="attr-meta-charset">charset</code> attribute or a
<code>meta</code> element with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-content-type">Encoding declaration
state</span>, then the character encoding used must be an
<span>ASCII-compatible character encoding</span>.</p>
<p>Authors are encouraged to use UTF-8. Conformance checkers may
advise authors against using legacy encodings.</p>
<div class="impl">
<p>Authoring tools should default to using UTF-8 for newly-created
documents.</p>
</div>
<p>Encodings in which a series of bytes in the range 0x20 to 0x7E
can encode characters other than the corresponding characters in the
range U+0020 to U+007E represent a potential security vulnerability:
a user agent that does not support the encoding (or does not support
the label used to declare the encoding, or does not use the same
mechanism to detect the encoding of unlabelled content as another
user agent) might end up interpreting technically benign plain text
content as HTML tags and JavaScript. For example, this applies to
encodings in which the bytes corresponding to "<code
title=""><script></code>" in ASCII can encode a different
string. Authors should not use such encodings, which are known to
include JIS_C6226-1983<!-- aka JIS-X-0208, x-JIS0208 -->,
JIS_X0212-1990<!-- aka JIS-X-0212 -->, HZ-GB-2312<!-- has crazy
handling of ASCII "~" -->, JOHAB <!-- a supplementary encoding in KS
C 5601-1992 Annex 3 (= KS X 1001:1998 Annex 3) --> (Windows code
page 1361), encodings based on ISO-2022<!--
http://krijnhoetmer.nl/irc-logs/whatwg/20090628#l-422 and
http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-October/023797.html
-->, and encodings based on EBCDIC. Furthermore, authors must not
use the CESU-8, UTF-7, BOCU-1 and SCSU encodings, which also fall
into this category, because these encodings were never intended for
use for Web content.
<a href="#refsRFC1345">[RFC1345]</a><!-- for the JIS types -->
<a href="#refsRFC1842">[RFC1842]</a><!-- HZ-GB-2312 -->
<a href="#refsRFC1468">[RFC1468]</a><!-- ISO-2022-JP -->
<a href="#refsRFC2237">[RFC2237]</a><!-- ISO-2022-JP-1 -->
<a href="#refsRFC1554">[RFC1554]</a><!-- ISO-2022-JP-2 -->
<a href="#refsRFC1922">[RFC1922]</a><!-- ISO-2022-CN and ISO-2022-CN-EXT -->
<a href="#refsRFC1557">[RFC1557]</a><!-- ISO-2022-KR -->
<a href="#refsCESU8">[CESU8]</a>
<a href="#refsUTF7">[UTF7]</a>
<a href="#refsBOCU1">[BOCU1]</a>
<a href="#refsSCSU">[SCSU]</a>
<!-- no idea what to reference for JOHAB or EBCDIC, so... -->
</p>
<p>Authors should not use UTF-32, as the HTML5 encoding detection
algorithms intentionally do not distinguish it from UTF-16. <a
href="#refsUNICODE">[UNICODE]</a></p>
<p class="note">Using non-UTF-8 encodings can have unexpected
results on form submission and URL encodings, which use the
<span>document's character encoding</span> by default.</p>
<p>In XHTML, the XML declaration should be used for inline character
encoding information, if necessary.</p>
<div class="example">
<p>In HTML, to declare that the character encoding is UTF-8, the
author could include the following markup near the top of the
document (in the <code>head</code> element):</p>
<pre><meta charset="utf-8"></pre>
<p>In XML, the XML declaration would be used instead, at the very
top of the markup:</p>
<pre><?xml version="1.0" encoding="utf-8"?></pre>
</div>
<h4>The <dfn><code>style</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Metadata content</span>.</dd>
<dd>If the <code title="attr-style-scoped">scoped</code> attribute is present: <span>flow content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>If the <code title="attr-style-scoped">scoped</code> attribute is absent: where <span>metadata content</span> is expected.</dd>
<dd>If the <code title="attr-style-scoped">scoped</code> attribute is absent: in a <code>noscript</code> element that is a child of a <code>head</code> element.</dd>
<dd>If the <code title="attr-style-scoped">scoped</code> attribute is present: where <span>flow content</span> is expected, but before any other <span>flow content</span> other than other <code>style</code> elements and <span>inter-element whitespace</span>.</dd>
<dt>Content model:</dt>
<dd>Depends on the value of the <code title="attr-style-type">type</code> attribute, but must match requirements described in prose below.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-style-media">media</code></dd>
<dd><code title="attr-style-type">type</code></dd>
<dd><code title="attr-style-scoped">scoped</code></dd>
<dd>Also, the <code title="attr-style-title">title</code> attribute has special semantics on this element.</dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLStyleElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-style-disabled">disabled</span>;
attribute DOMString <span title="dom-style-media">media</span>;
attribute DOMString <span title="dom-style-type">type</span>;
attribute boolean <span title="dom-style-scoped">scoped</span>;
};
<span>HTMLStyleElement</span> implements <span>LinkStyle</span>;</pre>
</dd>
</dl>
<p>The <code>style</code> element allows authors to embed style
information in their documents. The <code>style</code> element is
one of several inputs to the <span>styling processing
model</span>. The element does not <span
title="represents">represent</span> content for the user.</p>
<p>If the <dfn title="attr-style-type"><code>type</code></dfn>
attribute is given, it must contain a <span>valid MIME type</span>,
optionally with parameters, that designates a styling language. If
the attribute is absent, the type defaults to
<code>text/css</code>. <a href="#refsRFC2318">[RFC2318]</a></p>
<div class="impl">
<!-- this paragraph is also present in the <script> section -->
<p>When examining types to determine if they support the language,
user agents must not ignore unknown MIME parameters — types
with unknown parameters must be assumed to be unsupported.</p>
</div>
<p>The <dfn title="attr-style-media"><code>media</code></dfn>
attribute says which media the styles apply to. The value must be a
<span>valid media query</span>. <span class="impl">The user agent
must apply the styles to a <span>view</span> when the <code
title="attr-style-media">media</code> attribute's value
<span>matches the environment</span> of that view and the other
relevant conditions apply, and must not apply them
otherwise.</span></p><!-- note similar text in <link> section -->
<div class="impl">
<p class="note">The styles might be further limited in scope,
e.g. in CSS with the use of <code title="">@media</code>
blocks. This specification does not override such further
restrictions or requirements.</p><!-- note similar text in <link>
section -->
</div>
<p id="style-default-media">The default, if the <code
title="attr-style-media">media</code> attribute is omitted, is
"<code title="">all</code>", meaning that by default styles apply to
all media.</p>
<p>The <dfn title="attr-style-scoped"><code>scoped</code></dfn>
attribute is a <span>boolean attribute</span>. If set, it indicates
that the styles are intended just for the subtree rooted at the
<code>style</code> element's parent element, as opposed to the whole
<code>Document</code>.</p>
<div class="impl">
<p>If the <code title="attr-style-scoped">scoped</code> attribute is
present, then the user agent must apply the specified style
information only to the <code>style</code> element's parent element
(if any), and that element's child nodes. Otherwise, the specified
styles must, if applied, be applied to the entire document.</p>
</div>
<p id="title-on-style">The <dfn
title="attr-style-title"><code>title</code></dfn> attribute on
<code>style</code> elements defines <span>alternative style sheet
sets</span>. If the <code>style</code> element has no <code
title="attr-style-title">title</code> attribute, then it has no
title; the <code title="attr-title">title</code> attribute of
ancestors does not apply to the <code>style</code> element. <a
href="#refsCSSOM">[CSSOM]</a></p>
<p class="note">The <code title="attr-style-title">title</code>
attribute on <code>style</code> elements, like the <code
title="attr-link-title">title</code> attribute on <code>link</code>
elements, differs from the global <code
title="attr-title">title</code> attribute in that a
<code>style</code> block without a title does not inherit the title
of the parent element: it merely has no title.</p>
<p>The <code>textContent</code> of a <code>style</code> element must
match the <code title="">style</code> production in the following
ABNF, the character set for which is Unicode. <a
href="#refsABNF">[ABNF]</a></p>
<pre>style = no-c-start *( c-start no-c-end c-end no-c-start )
no-c-start = <any string that doesn't contain a substring that matches c-start >
c-start = "<!--"
no-c-end = <any string that doesn't contain a substring that matches c-end >
c-end = "-->"</pre>
<!-- Unmatched comment-like syntax is invalid on a temporary basis,
waiting for IE, WebKit, and Opera to fix their parsing bug
whereby such comments trigger a weird escape in which </style>
is ignored. Otherwise, parsing behaviour in those browsers
could differ substantially from the parsing behaviour of HTML5.
Once everyone follows the HTML5 spec, we can drop this
requirement.
-->
<div class="impl">
<p>All descendant elements must be processed, according to their
semantics, before the <code>style</code> element itself is
evaluated. For styling languages that consist of pure text, user
agents must evaluate <code>style</code> elements by passing the
concatenation of the contents of all the <span title="text
node">text nodes</span> that are direct children of the
<code>style</code> element (not any other nodes such as comments or
elements), in <span>tree order</span>, to the style system. For
XML-based styling languages, user agents must pass all the child
nodes of the <code>style</code> element to the style system.</p>
<p>All <span title="URL">URLs</span> found by the styling language's
processor must be <span title="resolve a url">resolved</span>,
relative to the element (or as defined by the styling language),
when the processor is invoked.<!-- so dynamic changes to the base
URL don't affect the CSS --></p>
<!-- the next few paragraph are similar to text in the <style> section -->
<p>Once the attempts to obtain the style sheet's critical
subresources, if any, are complete, or, if the style sheet has no
critical subresources, once the style sheet has been parsed and
processed, the user agent must, if the loads were successful or
there were none, <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-load">load</code> at the
<code>style</code> element, or, if one of the style sheet's critical
subresources failed to completely load for any reason (e.g. DNS
error, HTTP 404 response, a connection being prematurely closed,
unsupported Content-Type), <span>queue a task</span> to <span>fire a
simple event</span> named <code title="event-error">error</code> at
the <code>style</code> element. Non-network errors in processing the
style sheet or its subresources (e.g. CSS parse errors, PNG decoding
errors) are not failures for the purposes of this paragraph.</p>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <span>DOM manipulation task
source</span>.</p>
<p>The element must <span>delay the load event</span> of the
element's document until all the attempts to obtain the style
sheet's critical subresources, if any, are complete.</p>
<p>Which resources are considered critical or not is defined by the
relevant specification. For CSS resources, only <code
title="">@import</code> rules introduce critical subresources; other
resources, e.g. fonts or backgrounds, are not.</p>
</div>
<p class="note">This specification does not specify a style system,
but CSS is expected to be supported by most Web browsers. <a
href="#refsCSS">[CSS]</a></p>
<div class="impl">
<p>The <dfn title="dom-style-media"><code>media</code></dfn>, <dfn
title="dom-style-type"><code>type</code></dfn> and <dfn
title="dom-style-scoped"><code>scoped</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name.</p>
</div>
<p>The DOM <dfn
title="dom-style-disabled"><code>disabled</code></dfn> attribute
behaves as defined <span title="dom-linkstyle-disabled">for the
alternative style sheets DOM</span>.</p>
<p>The <code>LinkStyle</code> interface is also implemented by
this element; the <span>styling processing model</span> defines
how. <a href="#refsCSSOM">[CSSOM]</a></p>
<div class="example">
<p>The following document has its emphasis styled as bright red
text rather than italics text, while leaving titles of works and
Latin words in their default italics. It shows how using
appropriate elements enables easier restyling of documents.</p>
<pre><!DOCTYPE html>
<html lang="en-US">
<head>
<title>My favorite book</title>
<style>
body { color: black; background: white; }
em { font-style: normal; color: red; }
</style>
</head>
<body>
<p>My <em>favorite</em> book of all time has <em>got</em> to be
<cite>A Cat's Life</cite>. It is a book by P. Rahmel that talks
about the <i lang="la">Felis Catus</i> in modern human society.</p>
</body>
</html></pre>
</div>
<h4 id="styling"><dfn title="styling processing model">Styling</dfn></h4>
<p>The <code>link</code> and <code>style</code> elements can provide
styling information for the user agent to use when rendering the
document. The DOM Styling specification specifies what styling
information is to be used by the user agent and how it is to be
used. <a href="#refsCSSOM">[CSSOM]</a></p>
<p>The <code>style</code> and <code>link</code> elements implement
the <code>LinkStyle</code> interface. <a
href="#refsCSSOM">[CSSOM]</a></p>
<div class="impl">
<p>For <code>style</code> elements, if the user agent does not
support the specified styling language, then the <code
title="dom-LinkStyle-sheet">sheet</code> attribute of the element's
<code>LinkStyle</code> interface must return null. Similarly,
<code>link</code> elements that do not represent <span
title="rel-stylesheet">external resource links that contribute to
the styling processing model</span> (i.e. that do not have a <code
title="rel-stylesheet">stylesheet</code> keyword in their <code
title="attr-link-rel">rel</code> attribute), and <code>link</code>
elements whose specified resource has not yet been fetched, or is
not in a supported styling language, must have their
<code>LinkStyle</code> interface's <code
title="dom-LinkStyle-sheet">sheet</code> attribute return null.</p>
<p>Otherwise, the <code>LinkStyle</code> interface's <code
title="dom-LinkStyle-sheet">sheet</code> attribute must return a
<code>StyleSheet</code> object with the following properties: <a
href="#refsCSSOM">[CSSOM]</a></p>
<dl>
<dt>The style sheet type</dt>
<dd><p>The style sheet type must be the same as the style's specified
type. For <code>style</code> elements, this is the same as the
<code title="attr-style-type">type</code> content attribute's
value, or <code title="">text/css</code> if that is omitted. For
<code>link</code> elements, this is the <span
title="Content-Type">Content-Type metadata of the specified
resource</span>.</p></dd>
<dt>The style sheet location</dt>
<dd><p>For <code>link</code> elements, the location must be the
result of <span title="resolve a url">resolving</span> the
<span>URL</span> given by the element's <code
title="attr-link-href">href</code> content attribute, relative to
the element, or the empty string if that fails. For
<code>style</code> elements, there is no location.</p></dd> <!--
note that this might not match the style sheet URL, if the base URL
has changed for instance -->
<dt>The style sheet media</dt>
<dd><p>The media must be the same as the value of the element's
<code title="">media</code> content attribute, or the empty string,
if the attribute is omitted.</p></dd>
<dt>The style sheet title</dt>
<dd><p>The title must be the same as the value of the element's
<code title="dom-title">title</code> content attribute, if the
attribute is present and has a non-empty value. If the attribute is
absent or its value is the empty string, then the style sheet does
not have a title (it is the empty string). The title is used for
defining <span>alternative style sheet sets</span>.</p></dd>
<dt>The style sheet alternate flag</dt>
<dd><p>For <code>link</code> elements, true if <span>the link is an
alternative stylesheet</span>. In all other cases, false.</p></dd>
<!--
<dt>The style sheet disabled flag</dt>
(not included, because I assume CSSOM will change to not require
this spec to initialise the value, but will instead initialise it
based on the other values)
-->
</dl>
<p>The <dfn
title="dom-LinkStyle-disabled"><code>disabled</code></dfn> IDL
attribute on <code>link</code> and <code>style</code> elements must
return false and do nothing on setting, if the <code
title="dom-linkstyle-sheet">sheet</code> attribute of their
<code>LinkStyle</code> interface is null. Otherwise, it must return
the value of the <code>StyleSheet</code> interface's <code
title="dom-stylesheet-disabled">disabled</code> attribute on
getting, and forward the new value to that same attribute on
setting.</p>
<!-- [CSSOM] covers the following: the term "alternative style sheet
sets", the term "default style sheet set", preferred stylesheets,
alternative stylesheets, persistent stylesheets, ordering of
stylesheets, dynamic additions/removals, window.styleSheets, style
sheets given by HTTP Link: headers, and the alternative style sheet
API -->
<p id="alternate-style-sheets">The rules for handling alternative
style sheets are defined in the CSS object model specification. <a
href="#refsCSSOM">[CSSOM]</a></p>
<hr>
<p>Style sheets, whether added by a <code>link</code> element, a
<code>style</code> element, an <code><?xml-stylesheet></code> PI,
an HTTP <code title="http-link">Link:</code> header, or some other
mechanism, have a <dfn>style sheet ready</dfn> flag, which is
initially unset.</p>
<p>When a style sheet is ready to be applied, its <span>style sheet
ready</span> flag must be set. If the style sheet referenced no
other resources (e.g. it was an internal style sheet given by a
<code>style</code> element with no <code title="">@import</code>
rules), then the style rules must be synchronously made available to
script; otherwise, the style rules must only be made available to
script once the <span>event loop</span> reaches its "update the
rendering" step.</p>
<p>A style sheet in the context of the <code>Document</code> of an
<span>HTML parser</span> or <span>XML parser</span> is said to be
<dfn>a style sheet blocking scripts</dfn> if the element was created
by that <code>Document</code>'s parser, and the element is either a
<code>style</code> element or a <code>link</code> element that was
an <span title="rel-stylesheet">external resource link that
contributes to the styling processing model</span> when the element
was created by the parser, and the element's style sheet was enabled
when the element was created by the parser, and the element's
<span>style sheet ready</span> flag is not yet set, and, the last
time the <span>event loop</span> reached step 1, the element was
<span title="in a document">in that
<code>Document</code></span>.</p>
</div>
<h3>Scripting</h3>
<p>Scripts allow authors to add interactivity to their documents.</p>
<p>Authors are encouraged to use declarative alternatives to
scripting where possible, as declarative mechanisms are often more
maintainable, and many users disable scripting.</p>
<div class="example">
<p>For example, instead of using script to show or hide a section
to show more details, the <code>details</code> element could be
used.</p>
</div>
<p>Authors are also encouraged to make their applications degrade
gracefully in the absence of scripting support.</p>
<div class="example">
<p>For example, if an author provides a link in a table header to
dynamically resort the table, the link could also be made to
function without scripts by requesting the sorted table from the
server.</p>
</div>
<h4 id="script">The <dfn><code>script</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Metadata content</span>.</dd>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>metadata content</span> is expected.</dd>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>If there is no <code title="attr-script-src">src</code>
attribute, depends on the value of the <code
title="attr-script-type">type</code> attribute, but must match
<span>script content restrictions</span>.</dd>
<dd>If there <em>is</em> a <code title="attr-script-src">src</code>
attribute, the element must be either empty or contain only
<span>script documentation</span> that also matches <span>script
content restrictions</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-script-src">src</code></dd>
<dd><code title="attr-script-async">async</code></dd>
<dd><code title="attr-script-defer">defer</code></dd>
<dd><code title="attr-script-type">type</code></dd>
<dd><code title="attr-script-charset">charset</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLScriptElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-script-src">src</span>;
attribute boolean <span title="dom-script-async">async</span>;
attribute boolean <span title="dom-script-defer">defer</span>;
attribute DOMString <span title="dom-script-type">type</span>;
attribute DOMString <span title="dom-script-charset">charset</span>;
attribute DOMString <span title="dom-script-text">text</span>;
};</pre>
</dd>
</dl>
<p>The <code>script</code> element allows authors to include dynamic
script and data blocks in their documents. The element does not
<span title="represents">represent</span> content for the user.</p>
<p>When used to include dynamic scripts, the scripts may either be
embedded inline or may be imported from an external file using the
<code title="attr-script-src">src</code> attribute. If the language
is not that described by "<code title="">text/javascript</code>",
then the <code title="attr-script-type">type</code> attribute must
be present, as described below.</p>
<p>When used to include data blocks, the data must be embedded
inline, the format of the data must be given using the <code
title="attr-script-type">type</code> attribute, and the <code
title="attr-script-src">src</code> attribute must not be
specified.</p>
<p>The <dfn title="attr-script-type"><code>type</code></dfn>
attribute gives the language of the script or format of the data. If
the attribute is present, its value must be a <span>valid MIME
type</span>, optionally with parameters. The <code
title="">charset</code> parameter must not be specified. (The
default, which is used if the attribute is absent, is "<code
title="">text/javascript</code>".)</p>
<p>The <dfn title="attr-script-src"><code>src</code></dfn>
attribute, if specified, gives the address of the external script
resource to use. The value of the attribute must be a <span>valid
URL</span> identifying a script resource of the type given by the
<code title="attr-script-type">type</code> attribute, if the
attribute is present, or of the type "<code
title="">text/javascript</code>", if the attribute is absent. A
resource is a script resource of a given type if that type
identifies a scripting language and the resource conforms with the
requirements of that language's specification.</p>
<p>The <dfn title="attr-script-charset"><code>charset</code></dfn>
attribute gives the character encoding of the external script
resource. The attribute must not be specified if the <code
title="attr-script-src">src</code> attribute is not present. If the
attribute is set, its value must be a valid character encoding name,
must be an <span>ASCII case-insensitive</span> match for the
<span>preferred MIME name</span> for that encoding, and must match
the encoding given in the <code title="">charset</code> parameter of
the <span title="Content-Type">Content-Type metadata</span> of the
external file, if any. <a
href="#refsIANACHARSET">[IANACHARSET]</a></p>
<p>The <dfn title="attr-script-async"><code>async</code></dfn> and
<dfn title="attr-script-defer"><code>defer</code></dfn> attributes
are <span title="boolean attribute">boolean attributes</span> that
indicate how the script should be executed.</p>
<p>There are three possible modes that can be selected using these
attributes. If the <code title="attr-script-async">async</code>
attribute is present, then the script will be executed
asynchronously, as soon as it is available. If the <code
title="attr-script-async">async</code> attribute is not present but
the <code title="attr-script-defer">defer</code> attribute is
present, then the script is executed when the page has finished
parsing. If neither attribute is present, then the script is
fetched and executed immediately, before the user agent continues
parsing the page. The exact processing details for these attributes
are described below.</p>
<p>The <code title="attr-script-defer">defer</code> attribute may be
specified even if the <code title="attr-script-async">async</code>
attribute is specified, to cause legacy Web browsers that only
support <code title="attr-script-defer">defer</code> (and not <code
title="attr-script-async">async</code>) to fall back to the <code
title="attr-script-defer">defer</code> behavior instead of the
synchronous blocking behavior that is the default.</p>
<p>If one or both of the <code
title="attr-script-defer">defer</code> and <code
title="attr-script-async">async</code> attributes are specified, the
<code title="attr-script-src">src</code> attribute must also be
specified.</p>
<p>Changing the <code title="attr-script-src">src</code>, <code
title="attr-script-type">type</code>, <code
title="attr-script-charset">charset</code>, <code
title="attr-script-async">async</code>, and <code
title="attr-script-defer">defer</code> attributes dynamically has no
direct effect; these attribute are only used <span class="impl">at
specific times described below (namely,</span> when the element is
<span title="insert an element into a document">inserted into the
document</span><span class="impl">)</span>.</p> <!-- by implication,
changes to the base URL also have no effect -->
<div class="impl">
<p>A <code>script</code> element has several associated pieces of
state.</p>
<p>The first is a flag indicating whether or not the script block
has been <dfn>"already started"</dfn>. Initially,
<code>script</code> elements must have this flag unset (script
blocks, when created, are not "already started"). When a
<code>script</code> element is cloned, the "already started" flag,
if set, must be propagated to the clone when it is created.</p>
<p>The second is a flag indicating whether the element was
<dfn>"parser-inserted"</dfn>. Initially, <code>script</code>
elements must have this flag unset. It is set by the <span>HTML
parser</span> and is used to handle <code
title="dom-document-write">document.write()</code> calls.</p>
<p>The third is a flag indicating whether or not the script block is
<dfn>"ready to be parser-executed"</dfn>. Initially,
<code>script</code> elements must have this flag unset (script
blocks, when created, are not "ready to be parser-executed"). This
flag is used only for elements that are also
<span>"parser-inserted"</span>, to let the parser know when to
execute the script.</p>
<p>The fourth and fifth pieces of state are <dfn><var>the script
block's type</var></dfn> and <dfn><var>the script block's character
encoding</var></dfn>. They are determined when the script is run,
based on the attributes on the element at that time.</p>
<p>When a <code>script</code> element that is neither marked as
having <span>"already started"</span> nor marked as being
<span>"parser-inserted"</span> experiences one of the events listed
in the following list, the user agent must synchronously <span
title="running a script">run</span> the <code>script</code>
element:</p>
<ul>
<li>The <code>script</code> element gets <span title="insert an
element into a document">inserted into a document</span>.</li>
<li>The <code>script</code> element's child nodes are changed.</li>
<li>The <code>script</code> element has a <code
title="attr-script-src">src</code> attribute set where previously
the element had no such attribute.</li>
</ul>
<p><dfn title="running a script">Running a script</dfn>: When a
<code>script</code> element is to be run, the user agent must act as
follows:</p>
<ol>
<li>
<p>If either:</p>
<ul class="brief">
<li>the <code>script</code> element has a <code
title="attr-script-type">type</code> attribute and its value is
the empty string, or</li>
<li>the <code>script</code> element has no <code
title="attr-script-type">type</code> attribute but it has a <code
title="attr-script-language">language</code> attribute and
<em>that</em> attribute's value is the empty string, or</li>
<li>the <code>script</code> element has neither a <code
title="attr-script-type">type</code> attribute nor a <code
title="attr-script-language">language</code> attribute, then</li>
</ul>
<p>...let <var>the script block's type</var> for this
<code>script</code> element be "<code
title="">text/javascript</code>".</p>
<p>Otherwise, if the <code>script</code> element has a <code
title="attr-script-type">type</code> attribute, let <var>the
script block's type</var> for this <code>script</code> element be
the value of that attribute with any leading or trailing sequences
of <span title="space character">space characters</span>
removed.</p>
<p>Otherwise, the element has a non-empty <code
title="attr-script-language">language</code> attribute; let
<var>the script block's type</var> for this <code>script</code>
element be the concatenation of the string "<code
title="">text/</code>" followed by the value of the <code
title="attr-script-language">language</code> attribute.</p> <!--
user agents already support, e.g., type="text/javascript1.3", so
we don't have to support that separately. -->
<p class="note">The <code
title="attr-script-language">language</code> attribute is never
conforming, and is always ignored if there is a <code
title="attr-script-type">type</code> attribute present.</p>
</li>
<li>
<p>If the <code>script</code> element has a <code
title="attr-script-charset">charset</code> attribute, then let
<var>the script block's character encoding</var> for this
<code>script</code> element be the encoding given by the <code
title="attr-script-charset">charset</code> attribute.</p>
<p>Otherwise, let <var>the script block's character encoding</var>
for this <code>script</code> element be the same as <span
title="document's character encoding">the encoding of the document
itself</span>.</p>
</li>
<li>
<p>If the <code>script</code> element has a <code
title="attr-script-for">for</code> attribute, then the user agent
must abort these steps at this point. The script is not
executed.</p>
</li>
<li>
<p>If <span title="concept-n-noscript">scripting is
disabled</span> for the <code>script</code> element, or if the
user agent does not <span>support the scripting language</span>
given by <var>the script block's type</var> for this
<code>script</code> element, then the user agent must abort these
steps at this point. The script is not executed.</p>
</li>
<li>
<p>If the element has no <code title="attr-script-src">src</code>
attribute, and its child nodes consist only of comment nodes and
empty <span title="text node">text nodes</span>, then the user
agent must abort these steps at this point. The script is not
executed.</p>
</li>
<li>
<p>The user agent must set the element's <span>"already
started"</span> flag.</p>
</li>
<li>
<p>If the element has a <code title="attr-script-src">src</code>
attribute, then the value of that attribute must be <span
title="resolve a url">resolved</span> relative to the element, and
if that is successful, the specified resource must then be <span
title="fetch">fetched</span>, from the <span>origin</span> of the
element's <code>Document</code>.</p> <!-- not http-origin privacy
sensitive -->
<p>For historical reasons, if the <span>URL</span> is a <span
title="javascript protocol"><code title="">javascript:</code>
URL</span>, then the user agent must not, despite the requirements
in the definition of the <span title="fetch">fetching</span>
algorithm, actually execute the given script; instead the user
agent must act as if it had received an empty HTTP 400
response.</p>
<p>Once the resource's <span title="Content-Type">Content Type
metadata</span> is available, if it ever is, apply the
<span>algorithm for extracting an encoding from a
Content-Type</span> to it. If this returns an encoding, and the
user agent supports that encoding, then let <var>the script
block's character encoding</var> be that encoding.</p>
<p>For performance reasons, user agents may start fetching the
script as soon as the attribute is set, instead, in the hope that
the element will be inserted into the document. Either way, once
the element is <span title="insert an element into a
document">inserted into the document</span>, the load must have
started. If the UA performs such prefetching, but the element is
never inserted in the document, or the <code
title="attr-script-src">src</code> attribute is dynamically
changed,<!-- or the base URL is dynamically changed,--> then the
user agent will not execute the script, and the fetching process
will have been effectively wasted.</p>
</li>
<li>
<p>Then, the first of the following options that describes the
situation must be followed:</p>
<dl class="switch">
<dt>If the element has a <code title="attr-script-src">src</code>
attribute, and the element has a <code
title="attr-script-defer">defer</code> attribute, and the element
has been flagged as <span>"parser-inserted"</span>, and the
element does not have an <code
title="attr-script-async">async</code> attribute</dt>
<dd>
<p>The element must be added to the end of the <dfn>list of
scripts that will execute when the document has finished
parsing</dfn>.</p>
<p>The <span title="concept-task">task</span> that the
<span>networking task source</span> places on the <span>task
queue</span> once the <span title="fetch">fetching
algorithm</span> has completed must set the element's
<span>"ready to be parser-executed"</span> flag. The parser will
handle executing the script.</p>
</dd>
<dt>If the element has a <code title="attr-script-src">src</code>
attribute, and the element has been flagged as
<span>"parser-inserted"</span>, and the element does not have an
<code title="attr-script-async">async</code> attribute</dt>
<dd>
<p>The element is the <span>pending parsing-blocking
script</span>. (There can only be one such script at a
time.)</p>
<p>The <span title="concept-task">task</span> that the
<span>networking task source</span> places on the <span>task
queue</span> once the <span title="fetch">fetching
algorithm</span> has completed must set the element's
<span>"ready to be parser-executed"</span> flag. The parser will
handle executing the script.</p>
</dd>
<dt>If the element does not have a <code
title="attr-script-src">src</code> attribute, but there is
<span>a style sheet blocking scripts</span>, and the element has
been flagged as <span>"parser-inserted"</span></dt>
<dd>
<p>The element is the <span>pending parsing-blocking
script</span>. (There can only be one such script at a
time.)</p>
<p>Set the element's <span>"ready to be parser-executed"</span>
flag. The parser will handle executing the script.</p>
</dd>
<dt>If the element has a <code title="attr-script-src">src</code>
attribute</dt>
<dd>
<p>The element must be added to the end of the <dfn>list of
scripts that will execute as soon as possible</dfn>.</p>
<p>The <span title="concept-task">task</span> that the
<span>networking task source</span> places on the <span>task
queue</span> once the <span title="fetch">fetching
algorithm</span> has completed must <span title="executing a
script block">execute the script block</span>.
</dd>
<dt>Otherwise</dt>
<dd>The user agent must immediately <span title="executing a
script block">execute the script block</span>, even if other
scripts are already executing.</dd>
</dl>
</li>
</ol>
<!-- similar text in various places -->
<p>Fetching an external script must <span>delay the load
event</span> of the element's document until the <span
title="concept-task">task</span> that is <span title="queue a
task">queued</span> by the <span>networking task source</span> once
the resource has been <span title="fetch">fetched</span> (defined
above) has been run.</p>
<p>The <dfn>pending parsing-blocking script</dfn> is used by the
parser.</p>
<p><dfn title="executing a script block">Executing a script
block</dfn>: When the steps above require that the script block be
executed, the user agent must act as follows:</p>
<dl class="switch">
<dt>If the load resulted in an error (for example a DNS error, or
an HTTP 404 error)</dt>
<dd><p>Executing the script block must just consist of <span
title="fire a simple event">firing a simple event</span> named
<code title="event-error">error</code> at the element.</p></dd>
<dt>If the load was successful</dt>
<!-- SCRIPT EXEC -->
<dd>
<ol>
<li>
<p>Initialize <dfn><var>the script block's source</var></dfn> as
follows:</p>
<dl class="switch">
<dt>If the script is from an external file</dt>
<dd>
<p>The contents of that file, interpreted as string of
Unicode characters, are the script source.</p>
<p>For each of the rows in the following table, starting with
the first one and going down, if the file has as many or more
bytes available than the number of bytes in the first column,
and the first bytes of the file match the bytes given in the
first column, then set <var>the script block's character
encoding</var> to the encoding given in the cell in the second
column of that row, irrespective of any previous value:</p>
<!-- this table is present in several forms in this file; keep them in sync -->
<table>
<thead>
<tr>
<th>Bytes in Hexadecimal
<th>Encoding
<tbody>
<!-- nobody uses this
<tr>
<td>00 00 FE FF
<td>UTF-32BE
<tr>
<td>FF FE 00 00
<td>UTF-32LE
-->
<tr>
<td>FE FF
<td>UTF-16BE
<tr>
<td>FF FE
<td>UTF-16LE
<tr>
<td>EF BB BF
<td>UTF-8
<!-- nobody uses this
<tr>
<td>DD 73 66 73
<td>UTF-EBCDIC
-->
</table>
<p class="note">This step looks for Unicode Byte Order Marks
(BOMs).</p>
<p>The file must then be converted to Unicode using the
character encoding given by <var>the script block's character
encoding</var>.</p>
</dd>
<dt>If the script is inline and <var>the script block's type</var> is a text-based language</dt>
<dd>
<p>The value of the DOM <code
title="dom-script-text">text</code> attribute at the time the
"<span>running a script</span>" algorithm was first invoked is
the script source.</p>
</dd>
<dt>If the script is inline and <var>the script block's type</var> is an XML-based language</dt>
<dd>
<p>The child nodes of the <code>script</code> element at the
time the "<span>running a script</span>" algorithm was first
invoked are the script source.</p>
</dd>
</dl>
</li>
<li>
<p><span>Pause</span> until either any applicable style sheets
have been <span title="fetch">fetched</span> and applied, or the
user agent has timed out and decided to not wait for those style
sheets.</p>
<!-- TESTS: http://www.hixie.ch/tests/adhoc/html/script/loading/ -->
</li>
<li>
<p><span title="create a script from a node">Create a
script</span> from the <code>script</code> element node, using
<var>the script block's source</var> and <var>the script
block's type</var>.</p>
<p class="note">This is where the script is compiled and
actually executed.</p>
</li>
<li>
<p><span>Fire a simple event</span> named <code
title="event-load">load</code> at the <code>script</code>
element.</p>
</li>
</ol>
</dd>
</dl>
<p>The IDL attributes <dfn
title="dom-script-src"><code>src</code></dfn>, <dfn
title="dom-script-type"><code>type</code></dfn>, <dfn
title="dom-script-charset"><code>charset</code></dfn>, <dfn
title="dom-script-async"><code>async</code></dfn>, and <dfn
title="dom-script-defer"><code>defer</code></dfn>, each must
<span>reflect</span> the respective content attributes of the same
name.</p>
</div>
<dl class="domintro">
<dt><var title="">script</var> . <code title="dom-script-text">text</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the contents of the element, ignoring child nodes that
aren't <span title="text node">text nodes</span>.</p>
<p>Can be set, to replace the element's children with the given
value.</p>
</dd>
</dl>
<div class="impl">
<p>The IDL attribute <dfn
title="dom-script-text"><code>text</code></dfn> must return a
concatenation of the contents of all the <span title="text
node">text nodes</span> that are direct children of the
<code>script</code> element (ignoring any other nodes such as
comments or elements), in tree order. On setting, it must act the
same way as the <code>textContent</code> IDL attribute.</p>
</div>
<p class="note">When inserted using the <code
title="dom-document-write">document.write()</code> method,
<code>script</code> elements execute (typically synchronously), but
when inserted using <code
title="dom-innerHTML">innerHTML</code> and <code
title="dom-outerHTML">outerHTML</code> attributes, they do not
execute at all.</p>
<div class="example">
<p>In this example, two <code>script</code> elements are used. One
embeds an external script, and the other includes some data.</p>
<pre><script src="game-engine.js"></script>
<script type="text/x-game-map">
........U.........e
o............A....e
.....A.....AAA....e
.A..AAA...AAAAA...e
</script></pre>
<p>The data in this case might be used by the script to generate
the map of a video game. The data doesn't have to be used that way,
though; maybe the map data is actually embedded in other parts of
the page's markup, and the data block here is just used by the
site's search engine to help users who are looking for particular
features in their game maps.</p>
</div>
<div class="example">
<p>The following sample shows how a script element can be used to
define a function that is then used by other parts of the
document. It also shows how a <code>script</code> element can be
used to invoke script while the document is being parsed, in this
case to initialize the form's output.</p>
<pre><script>
function calculate(form) {
var price = 52000;
if (form.elements.brakes.checked)
price += 1000;
if (form.elements.radio.checked)
price += 2500;
if (form.elements.turbo.checked)
price += 5000;
if (form.elements.sticker.checked)
price += 250;
form.elements.result.value = price;
}
</script>
<form name="pricecalc" onsubmit="return false">
<fieldset>
<legend>Work out the price of your car</legend>
<p>Base cost: £52000.</p>
<p>Select additional options:</p>
<ul>
<li><label><input type=checkbox name=brakes> Ceramic brakes (£1000)</label></li>
<li><label><input type=checkbox name=radio> Satellite radio (£2500)</label></li>
<li><label><input type=checkbox name=turbo> Turbo charger (£5000)</label></li>
<li><label><input type=checkbox name=sticker> "XZ" sticker (£250)</label></li>
</ul>
<p>Total: £<output name=result onformchange="calculate(form)"></output></p>
</fieldset>
<script>
document.forms.pricecalc.dispatchFormChange();
</script>
</form></pre>
</div>
<h5 id="scriptingLanguages">Scripting languages</h5>
<div class="impl">
<p>A user agent is said to <dfn>support the scripting language</dfn>
if <var>the script block's type</var> is an <span>ASCII
case-insensitive</span> match for the <span>MIME type</span> string
of a scripting language that the user agent implements.</p>
</div>
<p>The following lists some <span>MIME type</span> strings and the
languages to which they refer:</p>
<dl>
<dt>"<code>application/ecmascript</code>"</dt>
<dt>"<code>application/javascript</code>"</dt>
<dt>"<code>application/x-ecmascript</code>"</dt>
<dt>"<code>application/x-javascript</code>"</dt>
<dt>"<code>text/ecmascript</code>"</dt>
<dt>"<code>text/javascript</code>"</dt>
<dt>"<code>text/javascript1.0</code>"</dt>
<dt>"<code>text/javascript1.1</code>"</dt>
<dt>"<code>text/javascript1.2</code>"</dt>
<dt>"<code>text/javascript1.3</code>"</dt>
<dt>"<code>text/javascript1.4</code>"</dt>
<dt>"<code>text/javascript1.5</code>"</dt>
<dt>"<code>text/jscript</code>"</dt>
<dt>"<code>text/livescript</code>"</dt>
<dt>"<code>text/x-ecmascript</code>"</dt>
<dt>"<code>text/x-javascript</code>"</dt>
<dd>JavaScript. <a href="#refsECMA262">[ECMA262]</a></dd>
<dt>"<code>text/javascript;e4x=1</code>"</dt>
<dd>JavaScript with ECMAScript for XML. <a href="#refsECMA357">[ECMA357]</a></dd>
</dl>
<div class="impl">
<p>User agents may support other <span title="MIME type">MIME
types</span> and other languages.</p>
<!-- this paragraph is also present in the <style> section -->
<p>When examining types to determine if they support the language,
user agents must not ignore unknown MIME parameters — types
with unknown parameters must be assumed to be unsupported. The <code
title="">charset</code> parameter must be treated as an unknown
parameter for the purpose of comparing <span title="MIME type">MIME
types</span> here.</p>
</div>
<h5><dfn title="script content restrictions">Restrictions for contents of <code>script</code> elements</dfn></h5>
<p>The <code>textContent</code> of a <code>script</code> element must match the
<code title="">script</code> production in the following ABNF, the
character set for which is Unicode. <a
href="#refsABNF">[ABNF]</a></p>
<pre>script = data1 *( escape [ script-start data3 ] "-->" data1 ) [ escape ]
escape = "<!--" data2 *( script-start data3 script-end data2 )
data1 = <any string that doesn't contain a substring that matches not-data1>
not-data1 = <!-- script-end / -->"<!--" <!-- the script-end is redundant here since it would close the element -->
data2 = <any string that doesn't contain a substring that matches not-data2>
not-data2 = <!-- script-end / -->script-start / "-->" <!-- the script-end is redundant here since it would close the element -->
data3 = <any string that doesn't contain a substring that matches not-data3>
not-data3 = script-end / "-->"
script-start = lt s c r i p t tag-end
script-end = lt slash s c r i p t tag-end
lt = %x003C ; U+003C LESS-THAN SIGN character (<)
slash = %x002F ; U+002F SOLIDUS character (/)
s = %x0053 ; U+0053 LATIN CAPITAL LETTER S
s =/ %x0073 ; U+0073 LATIN SMALL LETTER S
c = %x0043 ; U+0043 LATIN CAPITAL LETTER C
c =/ %x0063 ; U+0063 LATIN SMALL LETTER C
r = %x0052 ; U+0052 LATIN CAPITAL LETTER R
r =/ %x0072 ; U+0072 LATIN SMALL LETTER R
i = %x0049 ; U+0049 LATIN CAPITAL LETTER I
i =/ %x0069 ; U+0069 LATIN SMALL LETTER I
p = %x0050 ; U+0050 LATIN CAPITAL LETTER P
p =/ %x0070 ; U+0070 LATIN SMALL LETTER P
t = %x0054 ; U+0054 LATIN CAPITAL LETTER T
t =/ %x0074 ; U+0074 LATIN SMALL LETTER T
tag-end = %x0009 ; U+0009 CHARACTER TABULATION
tag-end =/ %x000A ; U+000A LINE FEED (LF)
tag-end =/ %x000C ; U+000C FORM FEED (FF)
tag-end =/ %x0020 ; U+0020 SPACE
tag-end =/ %x002F ; U+002F SOLIDUS (/)
tag-end =/ %x003E ; U+003E GREATER-THAN SIGN (>)</pre>
<p>When a <code>script</code> element contains <span>script
documentation</span>, there are further restrictions on the contents
of the element, as described in the section below.</p>
<h5><dfn title="script documentation">Inline documentation for external scripts</dfn></h5>
<p>If a <code>script</code> element's <code
title="attr-script-src">src</code> attribute is specified, then the
contents of the <code>script</code> element, if any, must be such
that the value of the DOM <code title="dom-script-text">text</code>
attribute, which is derived from the element's contents, matches the
<code title="">documentation</code> production in the following
ABNF, the character set for which is Unicode. <a
href="#refsABNF">[ABNF]</a></p>
<pre>documentation = *( *( space / tab / comment ) [ line-comment ] newline )
comment = slash star *( not-star / star not-slash ) 1*star slash
line-comment = slash slash *not-newline
; characters
tab = %x0009 ; U+0009 TAB
newline = %x000A ; U+000A LINE FEED (LF)
space = %x0020 ; U+0020 SPACE
star = %x002A ; U+002A ASTERISK (*)
slash = %x002F ; U+002F SOLIDUS (/)
not-newline = %x0000-0009 / %x000B-10FFFF
; a Unicode character other than U+000A LINE FEED (LF)
not-star = %x0000-0029 / %x002B-10FFFF
; a Unicode character other than U+002A ASTERISK (*)
not-slash = %x0000-002E / %x0030-10FFFF
; a Unicode character other than U+002F SOLIDUS (/)</pre>
<p class="note">This corresponds to putting the contents of the
element in JavaScript comments.</p>
<p class="note">This requirement is in addition to the earlier
restrictions on the syntax of contents of <code>script</code>
elements.</p>
<div class="example">
<p>This allows authors to include documentation, such as license
information or API information, inside their documents while still
referring to external script files. The syntax is constrained so
that authors don't accidentally include what looks like valid
script while also providing a <code
title="attr-script-src">src</code> attribute.</p>
<pre><script src="cool-effects.js">
// create new instances using:
// var e = new Effect();
// start the effect using .play, stop using .stop:
// e.play();
// e.stop();
</script></pre>
</div>
<h4>The <dfn><code>noscript</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Metadata content</span>.</dd>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>In a <code>head</code> element of an <span title="HTML documents">HTML document</span>, if there are no ancestor <code>noscript</code> elements.</dd>
<dd>Where <span>phrasing content</span> is expected in <span>HTML documents</span>, if there are no ancestor <code>noscript</code> elements.</dd>
<dt>Content model:</dt>
<dd>When <span title="concept-n-noscript">scripting is disabled</span>, in a <code>head</code> element: in any order, zero or more <code>link</code> elements, zero or more <code>style</code> elements, and zero or more <code>meta</code> elements.</dd>
<dd>When <span title="concept-n-noscript">scripting is disabled</span>, not in a <code>head</code> element: <span>transparent</span>, but there must be no <code>noscript</code> element descendants.</dd>
<dd>Otherwise: text that conforms to the requirements given in the prose.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>noscript</code> element <span>represents</span> nothing
if <span title="concept-n-script">scripting is enabled</span>, and
<span>represents</span> its children if <span
title="concept-n-noscript">scripting is disabled</span>. It is used
to present different markup to user agents that support scripting
and those that don't support scripting, by affecting how the
document is parsed.</p>
<p>When used in <span>HTML documents</span>, the allowed content
model is as follows:</p>
<dl>
<dt>In a <code>head</code> element, if <span
title="concept-n-noscript">scripting is disabled</span> for the
<code>noscript</code> element</dt>
<dd><p>The <code>noscript</code> element must contain only
<code>link</code>, <code>style</code>, and <code>meta</code>
elements.</p></dd>
<dt>In a <code>head</code> element, if <span
title="concept-n-script">scripting is enabled</span> for the
<code>noscript</code> element</dt>
<dd><p>The <code>noscript</code> element must contain only text,
except that invoking the <span>HTML fragment parsing
algorithm</span> with the <code>noscript</code> element as the <var
title="">context</var> element and the text contents as the <var
title="">input</var> must result in a list of nodes that consists
only of <code>link</code>, <code>style</code>, and
<code>meta</code> elements, and no <span title="parse error">parse
errors</span>.</p></dd>
<dt>Outside of <code>head</code> elements, if <span
title="concept-n-noscript">scripting is disabled</span> for the
<code>noscript</code> element</dt>
<dd><p>The <code>noscript</code> element's content model is
<span>transparent</span>, with the additional restriction that a
<code>noscript</code> element must not have a <code>noscript</code>
element as an ancestor (that is, <code>noscript</code> can't be
nested).</p></dd>
<dt>Outside of <code>head</code> elements, if <span
title="concept-n-script">scripting is enabled</span> for the
<code>noscript</code> element</dt>
<dd>
<p>The <code>noscript</code> element must contain only text,
except that the text must be such that running the following
algorithm results in a conforming document with no
<code>noscript</code> elements and no <code>script</code>
elements, and such that no step in the algorithm causes an
<span>HTML parser</span> to flag a <span>parse error</span>:</p>
<ol>
<li>Remove every <code>script</code> element from the
document.</li>
<li>Make a list of every <code>noscript</code> element in the
document. For every <code>noscript</code> element in that list,
perform the following steps:
<ol>
<li>Let the <var title="">parent element</var> be the parent
element of the <code>noscript</code> element.</li>
<li>Take all the children of the <var title="">parent element</var>
that come before the <code>noscript</code> element, and call these
elements <var title="">the before children</var>.</li>
<li>Take all the children of the <var title="">parent element</var>
that come <em>after</em> the <code>noscript</code> element, and
call these elements <var title="">the after children</var>.</li>
<li>Let <var title="">s</var> be the concatenation of all the
<span>text node</span> children of the <code>noscript</code>
element.</li>
<li>Set the <code title="dom-innerHTML">innerHTML</code>
attribute of the <var title="">parent element</var> to the value
of <var title="">s</var>. (This, as a side-effect, causes the
<code>noscript</code> element to be removed from the
document.)</li>
<li>Insert <var title="">the before children</var> at the start of
the <var title="">parent element</var>, preserving their original
relative order.</li>
<li>Insert <var title="">the after children</var> at the end of the
<var title="">parent element</var>, preserving their original
relative order.</li>
</ol>
</li>
</ol>
</dd>
</dl>
<p class="note">All these contortions are required because, for
historical reasons, the <code>noscript</code> element is handled
differently by the <span>HTML parser</span> based on whether <span
title="scripting flag">scripting was enabled or not</span> when the
parser was invoked.</p>
<p>The <code>noscript</code> element must not be used in <span>XML
documents</span>.</p>
<p class="note"><strong>The <code>noscript</code> element is only
effective in <span>the HTML syntax</span>, it has no effect in
<span>the XHTML syntax</span>.</strong></p>
<div class="impl">
<p>The <code>noscript</code> element has no other requirements. In
particular, children of the <code>noscript</code> element are not
exempt from <span>form submission</span>, scripting, and so forth,
even when <span title="concept-n-script">scripting is enabled</span>
for the element.</p>
</div>
<div class="example">
<p>In the following example, a <code>noscript</code> element is
used to provide fallback for a script.</p>
<pre><form action="calcSquare.php">
<p>
<label for=x>Number</label>:
<input id="x" name="x" type="number">
</p>
<script>
var x = document.getElementById('x');
var output = document.createElement('p');
output.textContent = 'Type a number; it will be squared right then!';
x.form.appendChild(output);
x.form.onsubmit = function () { return false; }
x.oninput = function () {
var v = x.valueAsNumber;
output.textContent = v + ' squared is ' + v * v;
};
</script>
<noscript>
<input type=submit value="Calculate Square">
</noscript>
</form></pre>
<p>When script is disabled, a button appears to do the calculation
on the server side. When script is enabled, the value is computed
on-the-fly instead.</p>
<p>The <code>noscript</code> element is a blunt
instrument. Sometimes, scripts might be enabled, but for some
reason the page's script might fail. For this reason, it's
generally better to avoid using <code>noscript</code>, and to
instead design the script to change the page from being a
scriptless page to a scripted page on the fly, as in the next
example:</p>
<pre><form action="calcSquare.php">
<p>
<label for=x>Number</label>:
<input id="x" name="x" type="number">
</p>
<strong><input id="submit" type=submit value="Calculate Square"></strong>
<script>
var x = document.getElementById('x');
var output = document.createElement('p');
output.textContent = 'Type a number; it will be squared right then!';
x.form.appendChild(output);
x.form.onsubmit = function () { return false; }
x.oninput = function () {
var v = x.valueAsNumber;
output.textContent = v + ' squared is ' + v * v;
};
<strong> var submit = document.getElementById('submit');
submit.parentNode.removeChild(submit);</strong>
</script>
</form></pre>
<p>The above technique is also useful in XHTML, since
<code>noscript</code> is not supported in <span>the XHTML
syntax</span>.</p>
</div>
<h3>Sections</h3>
<h4>The <dfn><code>body</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Sectioning root</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As the second element in an <code>html</code> element.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="handler-window-onafterprint">onafterprint</code></dd>
<dd><code title="handler-window-onbeforeprint">onbeforeprint</code></dd>
<dd><code title="handler-window-onbeforeunload">onbeforeunload</code></dd>
<dd><code title="handler-window-onblur">onblur</code></dd>
<dd><code title="handler-window-onerror">onerror</code></dd>
<dd><code title="handler-window-onfocus">onfocus</code></dd>
<dd><code title="handler-window-onhashchange">onhashchange</code></dd>
<dd><code title="handler-window-onload">onload</code></dd>
<dd><code title="handler-window-onmessage">onmessage</code></dd>
<dd><code title="handler-window-onoffline">onoffline</code></dd>
<dd><code title="handler-window-ononline">ononline</code></dd>
<dd><code title="handler-window-onpagehide">onpagehide</code></dd>
<dd><code title="handler-window-onpageshow">onpageshow</code></dd>
<dd><code title="handler-window-onpopstate">onpopstate</code></dd>
<dd><code title="handler-window-onredo">onredo</code></dd>
<dd><code title="handler-window-onresize">onresize</code></dd>
<dd><code title="handler-window-onstorage">onstorage</code></dd>
<dd><code title="handler-window-onundo">onundo</code></dd>
<dd><code title="handler-window-onunload">onunload</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLBodyElement</dfn> : <span>HTMLElement</span> {
attribute <span>Function</span> <span title="handler-window-onafterprint">onafterprint</span>;
attribute <span>Function</span> <span title="handler-window-onbeforeprint">onbeforeprint</span>;
attribute <span>Function</span> <span title="handler-window-onbeforeunload">onbeforeunload</span>;
attribute <span>Function</span> <span title="handler-window-onblur">onblur</span>;
attribute <span>Function</span> <span title="handler-window-onerror">onerror</span>;
attribute <span>Function</span> <span title="handler-window-onfocus">onfocus</span>;
attribute <span>Function</span> <span title="handler-window-onhashchange">onhashchange</span>;
attribute <span>Function</span> <span title="handler-window-onload">onload</span>;
attribute <span>Function</span> <span title="handler-window-onmessage">onmessage</span>;
attribute <span>Function</span> <span title="handler-window-onoffline">onoffline</span>;
attribute <span>Function</span> <span title="handler-window-ononline">ononline</span>;
attribute <span>Function</span> <span title="handler-window-onpopstate">onpopstate</span>;
attribute <span>Function</span> <span title="handler-window-onpagehide">onpagehide</span>;
attribute <span>Function</span> <span title="handler-window-onpageshow">onpageshow</span>;
attribute <span>Function</span> <span title="handler-window-onredo">onredo</span>;
attribute <span>Function</span> <span title="handler-window-onresize">onresize</span>;
attribute <span>Function</span> <span title="handler-window-onstorage">onstorage</span>;
attribute <span>Function</span> <span title="handler-window-onundo">onundo</span>;
attribute <span>Function</span> <span title="handler-window-onunload">onunload</span>;
};</pre>
</dd>
</dl>
<p>The <code>body</code> element <span>represents</span> the main
content of the document.</p>
<p>In conforming documents, there is only one <code>body</code>
element. The <code title="dom-document-body">document.body</code>
IDL attribute provides scripts with easy access to a document's
<code>body</code> element.</p>
<div class="impl">
<p class="note">Some DOM operations (for example, parts of the
<span>drag and drop</span> model) are defined in terms of "<span>the
body element</span>". This refers to a particular element in the
DOM, as per the definition of the term, and not any arbitrary
<code>body</code> element.</p>
</div>
<p>The <code>body</code> element exposes as <span>event handler
content attributes</span> a number of the <span>event
handlers</span> of the <code>Window</code> object. It also mirrors
their <span>event handler IDL attributes</span>.</p>
<p>The <code title="handler-window-onblur">onblur</code>, <code
title="handler-window-onerror">onerror</code>, <code
title="handler-window-onfocus">onfocus</code>, and <code
title="handler-window-onload">onload</code> <span>event
handlers</span> of the <code>Window</code> object, exposed on the
<code>body</code> element, shadow the generic <span>event
handlers</span> with the same names normally supported by <span>HTML
elements</span>.</p>
<p class="example">Thus, for example, a bubbling <code
title="event-error">error</code> event fired on a child of <span>the
body element</span> of a <code>Document</code> would first trigger
the <code title="handler-onerror">onerror</code> <span>event handler
content attributes</span> of that element, then that of the root
<code>html</code> element, and only <em>then</em> would it trigger
the <code title="handler-window-onerror">onerror</code> <span
title="event handler content attributes">event handler content
attribute</span> on the <code>body</code> element. This is because
the event would bubble from the target, to the <code>body</code>, to
the <code>html</code>, to the <code>Document</code>, to the
<code>Window</code>, and the <span title="event handlers">event
handler</span> on the <code>body</code> is watching the
<code>Window</code> not the <code>body</code>. A regular event
listener attached to the <code>body</code> using <code
title="">addEventListener()</code>, however, would fire when the
event bubbled through the <code>body</code> and not when it reaches
the <code>Window</code> object.</p>
<div class="example">
<p>This page updates an indicator to show whether or not the user
is online:</p>
<pre><!DOCTYPE HTML>
<html>
<head>
<title>Online or offline?</title>
<script>
function update(online) {
document.getElementById('status').textContent =
online ? 'Online' : 'Offline';
}
</script>
</head>
<body ononline="update(true)"
onoffline="update(false)"
onload="update(navigator.onLine)">
<p>You are: <span id="status">(Unknown)</span></p>
</body>
</html></pre>
</div>
<h4>The <dfn><code>section</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Sectioning content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>section</code> element <span>represents</span> a
generic document or application section. A section, in this context,
is a thematic grouping of content, typically with a heading.</p>
<p class="example">Examples of sections would be chapters, the
various tabbed pages in a tabbed dialog box, or the numbered
sections of a thesis. A Web site's home page could be split into
sections for an introduction, news items, contact information.</p>
<p class="note">Authors are encouraged to use the
<code>article</code> element instead of the <code>section</code>
element when it would make sense to syndicate the contents of the
element.</p>
<p class="note" id="use-div-for-wrappers">The <code>section</code>
element is not a generic container element. When an element is
needed for styling purposes or as a convenience for scripting,
authors are encouraged to use the <code>div</code> element
instead. A general rule is that the <code>section</code> element is
appropriate only if the element's contents would be listed
explicitly in the document's <span>outline</span>.</p>
<div class="example">
<p>In the following example, we see an article (part of a larger
Web page) about apples, containing two short sections.</p>
<pre><article>
<hgroup>
<h1>Apples</h1>
<h2>Tasty, delicious fruit!</h2>
</hgroup>
<p>The apple is the pomaceous fruit of the apple tree.</p>
<section>
<h1>Red Delicious</h1>
<p>These bright red apples are the most common found in many
supermarkets.</p>
</section>
<section>
<h1>Granny Smith</h1>
<p>These juicy, green apples make a great filling for
apple pies.</p>
</section>
</article></pre>
<p>Notice how the use of <code>section</code> means that the author
can use <code>h1</code> elements throughout, without having to
worry about whether a particular section is at the top level, the
second level, the third level, and so on.</p>
</div>
<div class="example">
<p>Here is a graduation programme with two sections, one for the
list of people graduating, and one for the description of the
ceremony.</p>
<pre><!DOCTYPE Html>
<Html
><Head
><Title
>Graduation Ceremony Summer 2022</Title
></Head
><Body
><H1
>Graduation</H1
><Section
><H1
>Ceremony</H1
><P
>Opening Procession</P
><P
>Speech by Validactorian</P
><P
>Speech by Class President</P
><P
>Presentation of Diplomas</P
><P
>Closing Speech by Headmaster</P
></Section
><Section
><H1
>Graduates</H1
><Ul
><Li
>Molly Carpenter</Li
><Li
>Anastasia Luccio</Li
><Li
>Ebenezar McCoy</Li
><Li
>Karrin Murphy</Li
><Li
>Thomas Raith</Li
><Li
>Susan Rodriguez</Li
></Ul
></Section
></Body
></Html></pre>
</div>
<h4>The <dfn><code>nav</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Sectioning content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>nav</code> element <span>represents</span> a section of
a page that links to other pages or to parts within the page: a
section with navigation links.</p>
<p>Not all groups of links on a page need to be in a
<code>nav</code> element — only sections that consist of major
navigation blocks are appropriate for the <code>nav</code>
element. In particular, it is common for footers to have a short
list of links to various pages of a site, such as the terms of
service, the home page, and a copyright page. The
<code>footer</code> element alone is sufficient for such cases,
without a <code>nav</code> element.</p>
<p class="note">User agents (such as screen readers) that are
targeted at users who can benefit from navigation information being
omitted in the initial rendering, or who can benefit from navigation
information being immediately available, can use this element as a
way to determine what content on the page to initially skip and/or
provide on request.</p>
<div class="example">
<p>In the following example, the page has several places where
links are present, but only one of those places is considered a
navigation section.</p>
<pre><body>
<header>
<h1>Wake up sheeple!</h1>
<p><a href="news.html">News</a> -
<a href="blog.html">Blog</a> -
<a href="forums.html">Forums</a></p>
<p>Last Modified: <time>2009-04-01</time></p>
<nav>
<h1>Navigation</h1>
<ul>
<li><a href="articles.html">Index of all articles</a></li>
<li><a href="today.html">Things sheeple need to wake up for today</a></li>
<li><a href="successes.html">Sheeple we have managed to wake</a></li>
</ul>
</nav>
</header>
<div>
<article>
<header>
<h1>My Day at the Beach</h1>
</header>
<div>
<p>Today I went to the beach and had a lot of fun.</p>
<em>...more content...</em>
</div>
<footer>
<p>Posted <time pubdate datetime="2009-10-10T14:36-08:00">Thursday</time>.</p>
</footer>
</article>
<em>...more blog posts...</em>
</div>
<footer>
<p>Copyright © 2006 The Example Company</p>
<p><a href="about.html">About</a> -
<a href="policy.html">Privacy Policy</a> -
<a href="contact.html">Contact Us</a></p>
</footer>
</body></pre>
<p>Notice the <code>div</code> element being used to wrap all the
contents of the page other than the header and footer, and all the
contents of the blog entry other than its header and footer.</p>
</div>
<div class="example">
<p>In the following example, there are two <code>nav</code>
elements, one for primary navigation around the site, and one for
secondary navigation around the page itself.</p>
<pre><body>
<h1>The Wiki Center Of Exampland</h1>
<nav>
<ul>
<li><a href="/">Home</a></li>
<li><a href="/events">Current Events</a></li>
<em>...more...</em>
</ul>
</nav>
<article>
<header>
<h1>Demos in Exampland</h1>
<p>Written by A. N. Other.</p>
</header>
<nav>
<ul>
<li><a href="#public">Public demonstrations</a></li>
<li><a href="#destroy">Demolitions</a></li>
<em>...more...</em>
</ul>
</nav>
<div>
<section id="public">
<h1>Public demonstrations</h1>
<p><em>...more...</em></p>
</section>
<section id="destroy">
<h1>Demolitions</h1>
<p><em>...more...</em></p>
</section>
<em>...more...</em>
</div>
<footer>
<p><a href="?edit">Edit</a> | <a href="?delete">Delete</a> | <a href="?Rename">Rename</a></p>
</footer>
</article>
<footer>
<p><small>© copyright 1998 Exampland Emperor</small></p>
</footer>
</body></pre>
</div>
<h4>The <dfn><code>article</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Sectioning content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>article</code> element <span>represents</span> a
component of a page that consists of a self-contained composition in
a document, page, application, or site and that is intended to be
independently distributable or reusable, e.g. in syndication. This
could be a forum post, a magazine or newspaper article, a Web log
entry, a user-submitted comment, an interactive widget or gadget, or
any other independent item of content.</p>
<p>When <code>article</code> elements are nested, the inner
<code>article</code> elements represent articles that are in
principle related to the contents of the outer article. For
instance, a Web log entry on a site that accepts user-submitted
comments could represent the comments as <code>article</code>
elements nested within the <code>article</code> element for the Web
log entry.</p>
<p>Author information associated with an <code>article</code>
element (q.v. the <code>address</code> element) does not apply to
nested <code>article</code> elements.</p>
<p class="note">When used specifically with content to be
redistributed in syndication, the <code>article</code> element is
similar in purpose to the <code title="">entry</code> element in
Atom. <a href="#refsATOM">[ATOM]</a>
<p class="note">The <code>time</code> element's <code
title="attr-time-pubdate">pubdate</code> attribute can be used to
provide the publication date for an <code>article</code>
element.</p>
<div id="article-example" class="example">
<p>This example shows a blog post using the <code>article</code>
element:</p>
<pre><article>
<header>
<h1>The Very First Rule of Life</h1>
<p><time pubdate datetime="2009-10-09T14:28-08:00"></time></p>
</header>
<p>If there's a microphone anywhere near you, assume it's hot and
sending whatever you're saying to the world. Seriously.</p>
<p><em>...</em></p>
<footer>
<a href="?comments=1">Show comments...</a>
</footer>
</article></pre>
<p>Here is that same blog post, but showing some of the comments:</p>
<pre><article>
<header>
<h1>The Very First Rule of Life</h1>
<p><time pubdate datetime="2009-10-09T14:28-08:00"></time></p>
</header>
<p>If there's a microphone anywhere near you, assume it's hot and
sending whatever you're saying to the world. Seriously.</p>
<p><em>...</em></p>
<section>
<h1>Comments</h1>
<article>
<header>
<p>Posted by: George Washington</p>
<p><time pubdate datetime="2009-10-10T19:10-08:00"></time></p>
</header>
<p>Yeah! Especially when talking about your lobbyist friends!</p>
</article>
<article>
<header>
<p>Posted by: George Hammond</p>
<p><time pubdate datetime="2009-10-10T19:15-08:00"></time></p>
</header>
<p>Hey, you have the same first name as me.</p>
</article>
</section>
</article></pre>
</div>
<h4>The <dfn><code>aside</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Sectioning content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>aside</code> element <span>represents</span> a section
of a page that consists of content that is tangentially related to
the content around the <code>aside</code> element, and which could
be considered separate from that content. Such sections are often
represented as sidebars in printed typography.</p>
<p>The element can be used for typographical effects like pull
quotes or sidebars, for advertising, for groups of <code>nav</code>
elements, and for other content that is considered separate from the
main content of the page.</p>
<p class="note">It's not appropriate to use the <code>aside</code>
element just for parentheticals, since those are part of the main
flow of the document.</p>
<div class="example">
<p>The following example shows how an aside is used to mark up
background material on Switzerland in a much longer news story on
Europe.</p>
<pre><aside>
<h1>Switzerland</h1>
<p>Switzerland, a land-locked country in the middle of geographic
Europe, has not joined the geopolitical European Union, though it is
a signatory to a number of European treaties.</p>
</aside></pre>
</div>
<div class="example">
<p>The following example shows how an aside is used to mark up
a pull quote in a longer article.</p>
<pre>...
<p>He later joined a large company, continuing on the same work.
<q>I love my job. People ask me what I do for fun when I'm not at
work. But I'm paid to do my hobby, so I never know what to
answer. Some people wonder what they would do if they didn't have to
work... but I know what I would do, because I was unemployed for a
year, and I filled that time doing exactly what I do now.</q></p>
<aside>
<q> People ask me what I do for fun when I'm not at work. But I'm
paid to do my hobby, so I never know what to answer. </q>
</aside>
<p>Of course his work — or should that be hobby? —
isn't his only passion. He also enjoys other pleasures.</p>
...</pre>
</div>
<div class="example">
<p>The following extract shows how <code>aside</code> can be used
for blogrolls and other side content on a blog:</p>
<pre><body>
<header>
<h1>My wonderful blog</h1>
<p>My tagline</p>
</header>
<aside>
<!-- <em>this aside contains two sections that are tangentially related
to the page, namely, links to other blogs, and links to blog posts
from this blog</em> -->
<nav>
<h1>My blogroll</h1>
<ul>
<li><a href="http://blog.example.com/">Example Blog</a>
</ul>
</nav>
<nav>
<h1>Archives</h1>
<ol reversed>
<li><a href="/last-post">My last post</a>
<li><a href="/first-post">My first post</a>
</ol>
</nav>
</aside>
<aside>
<!-- <em>this aside is tangentially related to the page also, it
contains twitter messages from the blog author</em> -->
<h1>Twitter Feed</h1>
<blockquote cite="http://twitter.example.net/t31351234">
<p>I'm on vacation, writing my blog.</p>
</blockquote>
<blockquote cite="http://twitter.example.net/t31219752">
<p>I'm going to go on vacation soon.</p>
</blockquote>
</aside>
<article>
<!-- <em>this is a blog post</em> -->
<h1>My last post</h1>
<p>This is my last post.</p>
<footer>
<p><a href="/last-post" rel=bookmark>Permalink</a>
</footer>
</article>
<article>
<!-- <em>this is also a blog post</em> -->
<h1>My last post</h1>
<p>This is my first post.</p>
<aside>
<!-- <em>this aside is about the blog post, since it's inside the
<article> element; it would be wrong, for instance, to put the
blogroll here, since the blogroll isn't really related to this post
specifically, only to the page as a whole</em> -->
<h1>Posting</h1>
<p>While I'm thinking about it, I wanted to say something about
posting. Posting is fun!</p>
</aside>
<footer>
<p><a href="/first-post" rel=bookmark>Permalink</a>
</footer>
</article>
<footer>
<nav>
<a href="/archives">Archives</a> —
<a href="/about">About me</a> —
<a href="/copyright">Copyright</a>
</nav>
</footer>
</body></pre>
</div>
<h4>The <dfn><code>h1</code></dfn>, <dfn><code>h2</code></dfn>,
<dfn><code>h3</code></dfn>, <dfn><code>h4</code></dfn>,
<dfn><code>h5</code></dfn>, and <dfn><code>h6</code></dfn>
elements</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Heading content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of an <code>hgroup</code> element.</dd>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLHeadingElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>These elements <span title="represents">represent</span> headings
for their sections.</p>
<p>The semantics and meaning of these elements are defined in the
section on <span>headings and sections</span>.</p>
<p>These elements have a <dfn>rank</dfn> given by the number in
their name. The <code>h1</code> element is said to have the highest
rank, the <code>h6</code> element has the lowest rank, and two
elements with the same name have equal rank.</p>
<div class="example">
<p>These two snippets are equivalent:</p>
<pre><body>
<h1>Let's call it a draw(ing surface)</h1>
<h2>Diving in</h2>
<h2>Simple shapes</h2>
<h2>Canvas coordinates</h2>
<h3>Canvas coordinates diagram</h3>
<h2>Paths</h2>
</body></pre>
<pre><body>
<h1>Let's call it a draw(ing surface)</h1>
<section>
<h1>Diving in</h1>
</section>
<section>
<h1>Simple shapes</h1>
</section>
<section>
<h1>Canvas coordinates</h1>
<section>
<h1>Canvas coordinates diagram</h1>
</section>
</section>
<section>
<h1>Paths</h1>
</section>
</body></pre>
</div>
<h4>The <dfn><code>hgroup</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Heading content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>One or more <code>h1</code>, <code>h2</code>, <code>h3</code>, <code>h4</code>, <code>h5</code>, and/or <code>h6</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>hgroup</code> element <span>represents</span> the
heading of a section. The element is used to group a set of
<code>h1</code>–<code>h6</code> elements when the heading has
multiple levels, such as subheadings, alternative titles, or
taglines.</p>
<p>For the purposes of document summaries, outlines, and the like,
the text of <code>hgroup</code> elements is defined to be the text
of the highest <span title="rank">ranked</span>
<code>h1</code>–<code>h6</code> element descendant of the
<code>hgroup</code> element, if there are any such elements, and the
first such element if there are multiple elements with that
<span>rank</span>. If there are no such elements, then the text of
the <code>hgroup</code> element is the empty string.</p>
<p>Other elements of <span>heading content</span> in the
<code>hgroup</code> element indicate subheadings or subtitles.</p>
<p>The <span>rank</span> of an <code>hgroup</code> element is the
rank of the highest-ranked <code>h1</code>–<code>h6</code>
element descendant of the <code>hgroup</code> element, if there are
any such elements, or otherwise the same as for an <code>h1</code>
element (the highest rank).</p>
<p>The section on <span>headings and sections</span>
defines how <code>hgroup</code> elements are assigned to individual
sections.</p>
<div class="example">
<p>Here are some examples of valid headings. In each case, the
emphasized text represents the text that would be used as the
heading in an application extracting heading data and ignoring
subheadings.</p>
<pre><hgroup>
<h1><strong>The reality dysfunction</strong></h1>
<h2>Space is not the only void</h2>
</hgroup></pre>
<pre><hgroup>
<h1><strong>Dr. Strangelove</strong></h1>
<h2>Or: How I Learned to Stop Worrying and Love the Bomb</h2>
</hgroup></pre>
<p>The point of using <code>hgroup</code> in these examples is to
mask the <code>h2</code> element (which acts as a secondary title)
from the <span>outline</span> algorithm.</p><!--
http://www.brucelawson.co.uk/2009/html-5-is-a-mess/#comment-618895
-->
</div>
<h4>The <dfn><code>header</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>, but with no <code>header</code> or
<code>footer</code> element descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>header</code> element <span>represents</span> a group
of introductory or navigational aids.</p>
<p class="note">A <code>header</code> element is intended to usually
contain the section's heading (an
<code>h1</code>–<code>h6</code> element or an
<code>hgroup</code> element), but this is not required. The
<code>header</code> element can also be used to wrap a section's
table of contents, a search form, or any relevant logos.</p>
<div class="example">
<p>Here are some sample headers. This first one is for a game:</p>
<pre><header>
<p>Welcome to...</p>
<h1>Voidwars!</h1>
</header></pre>
<p>The following snippet shows how the element can be used to mark
up a specification's header:</p>
<pre><header>
<hgroup>
<h1>Scalable Vector Graphics (SVG) 1.2</h1>
<h2>W3C Working Draft 27 October 2004</h2>
</hgroup>
<dl>
<dt>This version:</dt>
<dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20041027/">http://www.w3.org/TR/2004/WD-SVG12-20041027/</a></dd>
<dt>Previous version:</dt>
<dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20040510/">http://www.w3.org/TR/2004/WD-SVG12-20040510/</a></dd>
<dt>Latest version of SVG 1.2:</dt>
<dd><a href="http://www.w3.org/TR/SVG12/">http://www.w3.org/TR/SVG12/</a></dd>
<dt>Latest SVG Recommendation:</dt>
<dd><a href="http://www.w3.org/TR/SVG/">http://www.w3.org/TR/SVG/</a></dd>
<dt>Editor:</dt>
<dd>Dean Jackson, W3C, <a href="mailto:dean@w3.org">dean@w3.org</a></dd>
<dt>Authors:</dt>
<dd>See <a href="#authors">Author List</a></dd>
</dl>
<p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notic <em>...</em>
</header></pre>
</div>
<p class="note">The <code>header</code> element is not
<span>sectioning content</span>; it doesn't introduce a new
section.</p>
<div class="example">
<p>In this example, the page has a page heading given by the
<code>h1</code> element, and two subsections whose headings are
given by <code>h2</code> elements. The content after the
<code>header</code> element is still part of the last subsection
started in the <code>header</code> element, because the
<code>header</code> element doesn't take part in the
<span>outline</span> algorithm.</p>
<pre><body>
<header>
<h1>Little Green Guys With Guns</h1>
<nav>
<ul>
<li><a href="/games">Games</a>
<li><a href="/forum">Forum</a>
<li><a href="/download">Download</a>
</ul>
</nav>
<h2>Important News</h2> <!-- this starts a second subsection -->
<!-- this is part of the subsection entitled "Important News" -->
<p>To play today's games you will need to update your client.</p>
<h2>Games</h2> <!-- this starts a third subsection -->
</header>
<p>You have three active games:</p>
<!-- this is still part of the subsection entitled "Games" -->
...</pre>
</div>
<h4>The <dfn><code>footer</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>, but with no <code>header</code> or
<code>footer</code> element descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>footer</code> element <span>represents</span> a footer
for its nearest ancestor <span>sectioning content</span> or
<span>sectioning root</span> element. A footer typically contains
information about its section such as who wrote it, links to related
documents, copyright data, and the like.</p>
<p class="note">Contact information for the author or editor of a
section belongs in an <code>address</code> element, possibly itself
inside a <code>footer</code>.</p>
<p>Footers don't necessarily have to appear at the <em>end</em> of a
section, though they usually do.</p>
<p>When the <code>footer</code> element contains entire sections,
they <span title="represents">represent</span> appendices, indexes,
long colophons, verbose license agreements, and other such
content.</p>
<p class="note">The <code>footer</code> element is not
<span>sectioning content</span>; it doesn't introduce a new
section.</p>
<p>When the nearest ancestor <span>sectioning content</span> or
<span>sectioning root</span> element is <span>the body
element</span>, then it applies to the whole page.</p>
<div class="example">
<p>Here is a page with two footers, one at the top and one at the
bottom, with the same content:</p>
<pre><body>
<footer><a href="../">Back to index...</a></footer>
<hgroup>
<h1>Lorem ipsum</h1>
<h2>The ipsum of all lorems</h2>
</hgroup>
<p>A dolor sit amet, consectetur adipisicing elit, sed do eiusmod
tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim
veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex
ea commodo consequat. Duis aute irure dolor in reprehenderit in
voluptate velit esse cillum dolore eu fugiat nulla
pariatur. Excepteur sint occaecat cupidatat non proident, sunt in
culpa qui officia deserunt mollit anim id est laborum.</p>
<footer><a href="../">Back to index...</a></footer>
</body></pre>
</div>
<div class="example">
<p>Here is an example which shows the <code>footer</code> element
being used both for a site-wide footer and for a section
footer.</p>
<pre><!DOCTYPE HTML>
<HTML><HEAD>
<TITLE>The Ramblings of a Scientist</TITLE>
<BODY>
<H1>The Ramblings of a Scientist</H1>
<ARTICLE>
<H1>Episode 15</H1>
<VIDEO SRC="/fm/015.ogv" CONTROLS AUTOBUFFER>
<P><A HREF="/fm/015.ogv">Download video</A>.</P>
</VIDEO>
<FOOTER> <!-- footer for article -->
<P>Published <TIME PUBDATE DATETIME="2009-10-21T18:26-07:00"></TIME></P>
</FOOTER>
</ARTICLE>
<ARTICLE>
<H1>My Favorite Trains</H1>
<P>I love my trains. My favorite train of all time is a Köf.</P>
<P>It is fun to see them pull some coal cars because they look so
dwarfed in comparison.</P>
<FOOTER> <!-- footer for article -->
<P>Published <TIME PUBDATE DATETIME="2009-09-15T14:54-07:00"></TIME></P>
</FOOTER>
</ARTICLE>
<FOOTER> <!-- site wide footer -->
<NAV>
<P><A HREF="/credits.html">Credits</A> —
<A HREF="/tos.html">Terms of Service</A> —
<A HREF="/index.html">Blog Index</A></P>
</NAV>
<P>Copyright © 2009 Gordon Freeman</P>
</FOOTER>
</BODY>
</HTML></pre>
</div>
<h4>The <dfn><code>address</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>, but with no <span>heading
content</span> descendants, no <span>sectioning content</span>
descendants, and no <code>header</code>, <code>footer</code>, or
<code>address</code> element descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>address</code> element <span>represents</span> the
contact information for its nearest <code>article</code> or
<code>body</code> element ancestor. If that is <span>the body
element</span>, then the contact information applies to the document
as a whole.</p>
<div class="example">
<p>For example, a page at the W3C Web site related to HTML might
include the following contact information:</p>
<pre><ADDRESS>
<A href="../People/Raggett/">Dave Raggett</A>,
<A href="../People/Arnaud/">Arnaud Le Hors</A>,
contact persons for the <A href="Activity">W3C HTML Activity</A>
</ADDRESS></pre>
</div>
<p>The <code>address</code> element must not be used to represent
arbitrary addresses (e.g. postal addresses), unless those addresses
are in fact the relevant contact information. (The <code>p</code>
element is the appropriate element for marking up postal addresses
in general.)</p>
<p>The <code>address</code> element must not contain information
other than contact information.</p>
<div class="example">
<p>For example, the following is non-conforming use of the
<code>address</code> element:</p>
<pre class="bad"><ADDRESS>Last Modified: 1999/12/24 23:37:50</ADDRESS></pre>
</div>
<p>Typically, the <code>address</code> element would be included
along with other information in a <code>footer</code> element.</p>
<div class="impl">
<p>The contact information for a node <var title="">node</var> is a
collection of <code>address</code> elements defined by the first
applicable entry from the following list:</p>
<dl class="switch">
<dt>If <var title="">node</var> is an <code>article</code> element</dt>
<dt>If <var title="">node</var> is a <code>body</code> element</dt>
<dd>
<p>The contact information consists of all the
<code>address</code> elements that have <var title="">node</var>
as an ancestor and do not have another <code>body</code> or
<code>article</code> element ancestor that is a descendant of <var
title="">node</var>.</p>
</dd>
<dt>If <var title="">node</var> has an ancestor element that is an <code>article</code> element</dt>
<dt>If <var title="">node</var> has an ancestor element that is a <code>body</code> element</dt>
<dd>
<p>The contact information of <var title="">node</var> is the same
as the contact information of the nearest <code>article</code> or
<code>body</code> element ancestor, whichever is nearest.</p>
</dd>
<dt>If <var title="">node</var>'s <code>Document</code> has <span
title="the body element">a body element</span></dt>
<dd>
<p>The contact information of <var title="">node</var> is the same
as the contact information <span>the body element</span> of the
<code>Document</code>.</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p>There is no contact information for <var
title="">node</var>.</p>
</dd>
</dl>
<p>User agents may expose the contact information of a node to the
user, or use it for other purposes, such as indexing sections based
on the sections' contact information.</p>
</div>
<h4><dfn>Headings and sections</dfn></h4>
<p>The <code>h1</code>–<code>h6</code> elements and the
<code>hgroup</code> element are headings.</p>
<p>The first element of <span>heading content</span> in an element
of <span>sectioning content</span> <span>represents</span> the
heading for that section. Subsequent headings of equal or higher
<span>rank</span> start new (implied) sections, headings of lower
<span>rank</span> start implied subsections that are part of the
previous one. In both cases, the element <span>represents</span> the
heading of the implied section.</p>
<p><span>Sectioning content</span> elements are always considered
subsections of their nearest ancestor element of <span>sectioning
content</span>, regardless of what implied sections other headings
may have created.</p>
<p>Certain elements are said to be <dfn title="sectioning
root">sectioning roots</dfn>, including <code>blockquote</code> and
<code>td</code> elements. These elements can have their own
outlines, but the sections and headings inside these elements do not
contribute to the outlines of their ancestors.</p>
<ul class="brief category-list">
<li><code>blockquote</code></li>
<li><code>body</code></li>
<!-- v2DATAGRID <li><code>datagrid</code></li> -->
<li><code>details</code></li>
<li><code>fieldset</code></li>
<li><code>figure</code></li>
<li><code>td</code></li>
</ul>
<div class="example">
<p>For the following fragment:</p>
<pre><body>
<h1>Foo</h1>
<h2>Bar</h2>
<blockquote>
<h3>Bla</h3>
</blockquote>
<p>Baz</p>
<h2>Quux</h2>
<section>
<h3>Thud</h3>
</section>
<p>Grunt</p>
</body></pre>
<p>...the structure would be:</p>
<ol>
<li>
Foo (heading of explicit <code>body</code> section, containing the "Grunt" paragraph)
<ol>
<li>
Bar (heading starting implied section, containing a block quote and the "Baz" paragraph)
</li>
<li>
Quux (heading starting implied section)
</li>
<li>
Thud (heading of explicit <code>section</code> section)
</li>
</ol>
</li>
</ol>
<p>Notice how the <code>section</code> ends the earlier implicit
section so that a later paragraph ("Grunt") is back at the top
level.</p>
</div>
<p>Sections may contain headings of any <span>rank</span>, but
authors are strongly encouraged to either use only <code>h1</code>
elements, or to use elements of the appropriate <span>rank</span>
for the section's nesting level.</p>
<p>Authors are also encouraged to explicitly wrap sections in
elements of <span>sectioning content</span>, instead of relying on
the implicit sections generated by having multiple headings in one
element of <span>sectioning content</span>.</p>
<div class="example">
<p>For example, the following is correct:</p>
<pre><body>
<h4>Apples</h4>
<p>Apples are fruit.</p>
<section>
<h2>Taste</h2>
<p>They taste lovely.</p>
<h6>Sweet</h6>
<p>Red apples are sweeter than green ones.</p>
<h1>Color</h1>
<p>Apples come in various colors.</p>
</section>
</body></pre>
<p>However, the same document would be more clearly expressed
as:</p>
<pre><body>
<h1>Apples</h1>
<p>Apples are fruit.</p>
<section>
<h2>Taste</h2>
<p>They taste lovely.</p>
<section>
<h3>Sweet</h3>
<p>Red apples are sweeter than green ones.</p>
</section>
</section>
<section>
<h2>Color</h2>
<p>Apples come in various colors.</p>
</section>
</body></pre>
<p>Both of the documents above are semantically identical and would
produce the same outline in compliant user agents.</p>
</div>
<h5 id="outlines">Creating an outline</h5>
<div class="impl">
<!-- v2 idea: It would be nice if there was a way to use this to
autogenerate a table of contents or some such -->
<p>This section defines an algorithm for creating an outline for a
<span>sectioning content</span> element or a <span>sectioning
root</span> element. It is defined in terms of a walk over the nodes
of a DOM tree, in tree order, with each node being visited when it
is <i>entered</i> and when it is <i>exited</i> during the walk.</p>
</div>
<p>The <dfn>outline</dfn> for a <span>sectioning content</span>
element or a <span>sectioning root</span> element consists of a list
of one or more potentially nested <span
title="concept-section">sections</span>. A <dfn
title="concept-section">section</dfn> is a container that
corresponds to some nodes in the original DOM tree. Each section can
have one heading associated with it, and can contain any number of
further nested sections. <span class="impl">The algorithm for the
outline also associates each node in the DOM tree with a particular
section and potentially a heading.</span> (The sections in the
outline aren't <code>section</code> elements, though some may
correspond to such elements — they are merely conceptual
sections.)</p>
<div class="example">
<p>The following markup fragment:</p>
<pre><body>
<h1>A</h1>
<p>B</p>
<h2>C</h2>
<p>D</p>
<h2>E</h2>
<p>F</p>
</body></pre>
<p>...results in the following outline being created for the
<code>body</code> node (and thus the entire document):</p>
<ol class="brief">
<li>
<p>Section created for <code>body</code> node.</p>
<p>Associated with heading "A".</p>
<p>Also associated with paragraph "B".</p>
<p>Nested sections:</p>
<ol class="brief">
<li>
<p>Section implied for first <code>h2</code> element.</p>
<p>Associated with heading "C".</p>
<p>Also associated with paragraph "D".</p>
<p>No nested sections.</p>
</li>
<li>
<p>Section implied for second <code>h2</code> element.</p>
<p>Associated with heading "E".</p>
<p>Also associated with paragraph "F".</p>
<p>No nested sections.</p>
</li>
</ol>
</li>
</ol>
</div>
<div class="impl">
<p>The algorithm that must be followed during a walk of a DOM
subtree rooted at a <span>sectioning content</span> element or a
<span>sectioning root</span> element to determine that element's
<span>outline</span> is as follows:</p>
<ol>
<li><p>Let <var title="">current outlinee</var> be null. (It holds
the element whose <span>outline</span> is being created.)</p></li>
<li><p>Let <var title="">current section</var> be null. (It holds a
pointer to a <span title="concept-section">section</span>, so that
elements in the DOM can all be associated with a section.)</p></li>
<li><p>Create a stack to hold elements, which is used to handle
nesting. Initialize this stack to empty.</p></li>
<li>
<p>As you walk over the DOM in <span>tree order</span>, trigger
the first relevant step below for each element as you enter and
exit it.</p>
<dl class="switch">
<dt>If the top of the stack is an element, and you are exiting
that element</dt>
<dd>
<p class="note">The element being exited is a <span>heading
content</span> element.</p>
<p>Pop that element from the stack.</p>
</dd>
<dt>If the top of the stack is a <span>heading content</span>
element</dt>
<dd><p>Do nothing.</p></dd>
<dt>When entering a <span>sectioning content</span> element or a
<span>sectioning root</span> element</dt>
<dd>
<p>If <var title="">current outlinee</var> is not null, and the
<var title="">current section</var> has no heading, create an
implied heading and let that be the heading for the <var
title="">current section</var>.</p>
<p>If <var title="">current outlinee</var> is not null, push
<var title="">current outlinee</var> onto the stack.</p>
<p>Let <var title="">current outlinee</var> be the element
that is being entered.</p>
<p>Let <var title="">current section</var> be a newly created
<span title="concept-section">section</span> for the <var
title="">current outlinee</var> element.</p>
<p>Let there be a new <span>outline</span> for the new <var
title="">current outlinee</var>, initialized with just the new
<var title="">current section</var> as the only <span
title="concept-section">section</span> in the outline.</p>
</dd>
<dt>When exiting a <span>sectioning content</span> element, if
the stack is not empty</dt>
<dd>
<p>Pop the top element from the stack, and let the <var
title="">current outlinee</var> be that element.</p>
<p>Let <var title="">current section</var> be the last section
in the <span>outline</span> of the <var title="">current
outlinee</var> element.</p>
<p>Append the <span>outline</span> of the <span>sectioning
content</span> element being exited to the <var title="">current
section</var>. (This does not change which section is the last
section in the <span>outline</span>.)</p>
</dd>
<dt>When exiting a <span>sectioning root</span> element, if the
stack is not empty</dt>
<dd>
<p>Run these steps:</p>
<ol>
<li><p>Pop the top element from the stack, and let the <var
title="">current outlinee</var> be that element.</p></li>
<li><p>Let <var title="">current section</var> be the last
section in the <span>outline</span> of the <var title="">current
outlinee</var> element.</p></li>
<li><p><i>Finding the deepest child</i>: If <var
title="">current section</var> has no child sections, stop
these steps.</p></li>
<li><p>Let <var title="">current section</var> be the last
child <span title="concept-section">section</span> of the
current <var title="">current section</var>.</p></li>
<li><p>Go back to the substep labeled <i>finding the deepest
child</i>.</p></li>
</ol>
</dd>
<dt>When exiting a <span>sectioning content</span> element or a
<span>sectioning root</span> element</dt>
<dd>
<p class="note">The <var title="">current outlinee</var> is
the element being exited.</p>
<p>Let <var title="">current section</var> be the first <span
title="concept-section">section</span> in the
<span>outline</span> of the <var title="">current outlinee</var>
element.</p>
<p>Skip to the next step in the overall set of steps. (The walk
is over.)</p>
</dd>
<dt>If the <var title="">current outlinee</var> is null.</dt>
<dd><p>Do nothing.</p></dd>
<dt>When entering a <span>heading content</span> element</dt>
<dd>
<p>If the <var title="">current section</var> has no heading,
let the element being entered be the heading for the <var
title="">current section</var>.</p>
<p>Otherwise, if the element being entered has a
<span>rank</span> equal to or greater than the heading of the
last section of the <span>outline</span> of the <var
title="">current outlinee</var>, then create a new <span
title="concept-section">section</span> and append it to the
<span>outline</span> of the <var title="">current outlinee</var>
element, so that this new section is the new last section of
that outline. Let <var title="">current section</var> be that
new section. Let the element being entered be the new heading
for the <var title="">current section</var>.</p>
<p>Otherwise, run these substeps:</p>
<ol>
<li><p>Let <var title="">candidate section</var> be <var
title="">current section</var>.</p></li>
<li><p>If the element being entered has a <span>rank</span>
lower than the <span>rank</span> of the heading of the <var
title="">candidate section</var>, then create a new <span
title="concept-section">section</span>, and append it to <var
title="">candidate section</var>. (This does not change which
section is the last section in the outline.) Let <var
title="">current section</var> be this new section. Let the
element being entered be the new heading for the <var
title="">current section</var>. Abort these substeps.</p>
<li><p>Let <var title="">new candidate section</var> be the
<span title="concept-section">section</span> that contains <var
title="">candidate section</var> in the <span>outline</span> of
<var title="">current outlinee</var>.</p></li>
<li><p>Let <var title="">candidate section</var> be <var
title="">new candidate section</var>.</p></li>
<li><p>Return to step 2.</p></li>
</ol>
<p>Push the element being entered onto the stack. (This causes
the algorithm to skip any descendants of the element.)</p>
<p class="note">Recall that <code>h1</code> has the
<em>highest</em> rank, and <code>h6</code> has the lowest
rank.</p>
</dd>
<dt>Otherwise</dt>
<dd><p>Do nothing.</p></dd>
</dl>
<p id="associatedSection">In addition, whenever you exit a node,
after doing the steps above, if <var title="">current
section</var> is not null, associate the node with the <span
title="concept-section">section</span> <var title="">current
section</var>.</p>
</li>
<li><p>If the <var title="">current outlinee</var> is null,
then there was no <span>sectioning content</span> element or
<span>sectioning root</span> element in the DOM. There is no
<span>outline</span>. Abort these steps.</p></li>
<li><p>Associate any nodes that were not associated with a <span
title="concept-section">section</span> in the steps above with <var
title="">current outlinee</var> as their section.</p></li>
<li><p>Associate all nodes with the heading of the <span
title="concept-section">section</span> with which they are
associated, if any.</p></li>
<li><p>If <var title="">current outlinee</var> is <span>the body
element</span>, then the outline created for that element is the
<span>outline</span> of the entire document.</p></li>
</ol>
<p>The tree of sections created by the algorithm above, or a proper
subset thereof, must be used when generating document outlines, for
example when generating tables of contents.</p>
<p>When creating an interactive table of contents, entries should
jump the user to the relevant <span>sectioning content</span>
element, if the <span title="concept-section">section</span> was
created for a real element in the original document, or to the
relevant <span>heading content</span> element, if the <span
title="concept-section">section</span> in the tree was generated for
a heading in the above process.</p>
<p class="note">Selecting the first <span
title="concept-section">section</span> of the document therefore
always takes the user to the top of the document, regardless of
where the first heading in the <code>body</code> is to be found.</p>
<p>The <dfn>outline depth</dfn> of a <span>heading content</span>
element associated with a <span
title="concept-section">section</span> <var title="">section</var>
is the number of <span title="concept-section">sections</span> that
are ancestors of <var title="">section</var> in the
<span>outline</span> that <var title="">section</var> finds itself
in when the <span title="outline">outlines</span> of its
<code>Document</code>'s elements are created, plus 1. The
<span>outline depth</span> of a <span>heading content</span> element
not associated with a <span title="concept-section">section</span>
is 1.</p>
<p>User agents should provide default headings for sections that do
not have explicit section headings.</p>
<div class="example">
<p>Consider the following snippet:</p>
<pre><body>
<nav>
<p><a href="/">Home</a></p>
</nav>
<p>Hello world.</p>
<aside>
<p>My cat is cute.</p>
</aside>
</body></pre>
<p>Although it contains no headings, this snippet has three
sections: a document (the <code>body</code>) with two subsections
(a <code>nav</code> and an <code>aside</code>). A user agent could
present the outline as follows:</p>
<ol class="brief">
<li>Untitled document
<ol>
<li>Navigation</li>
<li>Sidebar</li>
</ol>
</li>
</ol>
<p>These default headings ("Untitled document", "Navigation",
"Sidebar") are not specified by this specification, and might vary
with the user's language, the page's language, the user's
preferences, the user agent implementor's preferences, etc.</p>
</div>
<div class="note">
<p>The following JavaScript function shows how the tree walk could
be implemented. The <var title="">root</var> argument is the root
of the tree to walk, and the <var title="">enter</var> and <var
title="">exit</var> arguments are callbacks that are called with
the nodes as they are entered and exited. <a
href="#refsECMA262">[ECMA262]</a></p>
<pre>function (root, enter, exit) {
var node = root;
start: while (node) {
enter(node);
if (node.firstChild) {
node = node.firstChild;
continue start;
}
while (node) {
exit(node);
if (node.nextSibling) {
node = node.nextSibling;
continue start;
}
if (node == root)
node = null;
else
node = node.parentNode;
}
}
}</pre>
</div>
</div>
<h3>Grouping content</h3>
<h4>The <dfn><code>p</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLParagraphElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>p</code> element <span>represents</span> a
<span>paragraph</span>.</p>
<div class="example">
<p>The following examples are conforming HTML fragments:</p>
<pre><p>The little kitten gently seated himself on a piece of
carpet. Later in his life, this would be referred to as the time the
cat sat on the mat.</p></pre>
<pre><fieldset>
<legend>Personal information</legend>
<p>
<label>Name: <input name="n"></label>
<label><input name="anon" type="checkbox"> Hide from other users</label>
</p>
<p><label>Address: <textarea name="a"></textarea></label></p>
</fieldset></pre>
<pre><p>There was once an example from Femley,<br>
Whose markup was of dubious quality.<br>
The validator complained,<br>
So the author was pained,<br>
To move the error from the markup to the rhyming.</p></pre>
</div>
<p>The <code>p</code> element should not be used when a more
specific element is more appropriate.</p>
<div class="example">
<p>The following example is technically correct:</p>
<pre><section>
<!-- ... -->
<p>Last modified: 2001-04-23</p>
<p>Author: fred@example.com</p>
</section></pre>
<p>However, it would be better marked-up as:</p>
<pre><section>
<!-- ... -->
<footer>Last modified: 2001-04-23</footer>
<address>Author: fred@example.com</address>
</section></pre>
<p>Or:</p>
<pre><section>
<!-- ... -->
<footer>
<p>Last modified: 2001-04-23</p>
<address>Author: fred@example.com</address>
</footer>
</section></pre>
</div>
<h4>The <dfn><code>hr</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLHRElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>hr</code> element <span>represents</span> a
<span>paragraph</span>-level thematic break, e.g. a scene change in
a story, or a transition to another topic within a section of a
reference book.</p>
<div class="example">
<p>The following extract from <cite>Pandora's Star</cite> by Peter
F. Hamilton shows two paragraphs that precede a scene change and
the paragraph that follows it. The scene change, represented in the
printed book by a gap containing a solitary centered star between
the second and third paragraphs, is here represented using the
<code>hr</code> element.</p>
<!-- ISBN 1-4050-0020-1; bottom of page 14 -->
<pre lang="en-GB"><p>Dudley was ninety-two, in his second life, and fast approaching
time for another rejuvenation. Despite his body having the physical
age of a standard fifty-year-old, the prospect of a long degrading
campaign within academia was one he regarded with dread. For a
supposedly advanced civilization, the Intersolar Commonwearth could be
appallingly backward at times, not to mention cruel.</p>
<p><i>Maybe it won't be that bad</i>, he told himself. The lie was
comforting enough to get him through the rest of the night's
shift.</p>
<strong><hr></strong>
<p>The Carlton AllLander drove Dudley home just after dawn. Like the
astronomer, the vehicle was old and worn, but perfectly capable of
doing its job. It had a cheap diesel engine, common enough on a
semi-frontier world like Gralmond, although its drive array was a
thoroughly modern photoneural processor. With its high suspension and
deep-tread tyres it could plough along the dirt track to the
observatory in all weather and seasons, including the metre-deep snow
of Gralmond's winters.</p></pre>
</div>
<h4>The <dfn><code>br</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLBRElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>br</code> element <span>represents</span> a line
break.</p>
<p><code>br</code> elements must be used only for line breaks that
are actually part of the content, as in poems or addresses.</p>
<div class="example">
<p>The following example is correct usage of the <code>br</code>
element:</p>
<pre><p>P. Sherman<br>
42 Wallaby Way<br>
Sydney</p></pre>
</div>
<p><code>br</code> elements must not be used for separating thematic
groups in a paragraph.</p>
<div class="example">
<p>The following examples are non-conforming, as they abuse the
<code>br</code> element:</p>
<pre><p><a ...>34 comments.</a><br>
<a ...>Add a comment.</a></p></pre>
<pre><p><label>Name: <input name="name"></label><br>
<label>Address: <input name="address"></label></p></pre>
<p>Here are alternatives to the above, which are correct:</p>
<pre><p><a ...>34 comments.</a></p>
<p><a ...>Add a comment.</a></p></pre>
<pre><p><label>Name: <input name="name"></label></p>
<p><label>Address: <input name="address"></label></p></pre>
</div>
<p>If a <span>paragraph</span> consists of nothing but a single
<code>br</code> element, it represents a placeholder blank line
(e.g. as in a template). Such blank lines must not be used for
presentation purposes.</p>
<div class="impl">
<p>Any content inside <code>br</code> elements must not be
considered part of the surrounding text.</p>
</div>
<h4>The <dfn><code>pre</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLPreElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>pre</code> element <span>represents</span> a block of
preformatted text, in which structure is represented by typographic
conventions rather than by elements.</p>
<p class="note">In <span>the HTML syntax</span>, a leading
newline character immediately following the <code>pre</code> element
start tag is stripped.</p>
<p>Some examples of cases where the <code>pre</code> element could
be used:</p>
<ul>
<li>Including an e-mail, with paragraphs indicated by blank lines,
lists indicated by lines prefixed with a bullet, and so on.</li>
<li>Including fragments of computer code, with structure indicated
according to the conventions of that language.</li>
<li>Displaying ASCII art.</li>
</ul>
<p class="note">Authors are encouraged to consider how preformatted
text will be experienced when the formatting is lost, as will be the
case for users of speech synthesizers, braille displays, and the
like. For cases like ASCII art, it is likely that an alternative
presentation, such as a textual description, would be more
universally accessible to the readers of the document.</p>
<p>To represent a block of computer code, the <code>pre</code>
element can be used with a <code>code</code> element; to represent a
block of computer output the <code>pre</code> element can be used
with a <code>samp</code> element. Similarly, the <code>kbd</code>
element can be used within a <code>pre</code> element to indicate
text that the user is to enter.</p>
<div class="example">
<p>In the following snippet, a sample of computer code is
presented.</p>
<pre><p>This is the <code>Panel</code> constructor:</p>
<pre><code>function Panel(element, canClose, closeHandler) {
this.element = element;
this.canClose = canClose;
this.closeHandler = function () { if (closeHandler) closeHandler() };
}</code></pre></pre>
</div>
<div class="example">
<p>In the following snippet, <code>samp</code> and <code>kbd</code>
elements are mixed in the contents of a <code>pre</code> element to
show a session of Zork I.</p>
<pre><pre><samp>You are in an open field west of a big white house with a boarded
front door.
There is a small mailbox here.
></samp> <kbd>open mailbox</kbd>
<samp>Opening the mailbox reveals:
A leaflet.
></samp></pre></pre>
</div>
<div class="example">
<p>The following shows a contemporary poem that uses the
<code>pre</code> element to preserve its unusual formatting, which
forms an intrinsic part of the poem itself.</p>
<pre><pre> maxling
it is with a heart
heavy
that i admit loss of a feline
so loved
a friend lost to the
unknown
(night)
~cdr 11dec07</pre></pre>
</div>
<h4>The <dfn><code>blockquote</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Sectioning root</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-blockquote-cite">cite</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLQuoteElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-quote-cite">cite</span>;
};</pre>
<p class="note">The <code>HTMLQuoteElement</code> interface is
also used by the <code>q</code> element.</p>
</dd>
</dl>
<p>The <code>blockquote</code> element <span>represents</span> a
section that is quoted from another source.</p>
<p>Content inside a <code>blockquote</code> must be quoted from
another source, whose address, if it has one, should be cited in the
<dfn title="attr-blockquote-cite"><code>cite</code></dfn>
attribute.</p>
<p>If the <code title="attr-blockquote-cite">cite</code> attribute
is present, it must be a <span>valid URL</span>. <span
class="impl">To obtain the corresponding citation link, the value of
the attribute must be <span title="resolve a url">resolved</span>
relative to the element. User agents should allow users to follow
such citation links.</span></p>
<div class="impl">
<p>The <dfn title="dom-quote-cite"><code>cite</code></dfn> IDL
attribute must <span>reflect</span> the element's <code
title="">cite</code> content attribute.</p>
</div>
<div class="example">
<p>This next example shows the use of <code>cite</code> alongside
<code>blockquote</code>:</p>
<pre><p>His next piece was the aptly named <cite>Sonnet 130</cite>:</p>
<blockquote cite="http://quotes.example.org/s/sonnet130.html">
<p>My mistress' eyes are nothing like the sun,<br>
Coral is far more red, than her lips red,<br>
...</pre>
</div>
<p class="note"><a href="#conversations">Examples of how to
represent a conversation</a> are shown below; it is not appropriate
to use the <code>cite</code> and <code>blockquote</code> elements
for this purpose.</p>
<h4>The <dfn><code>ol</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>li</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-ol-reversed">reversed</code></dd>
<dd><code title="attr-ol-start">start</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLOListElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-ol-reversed">reversed</span>;
attribute long <span title="dom-ol-start">start</span>;
};</pre>
</dd>
</dl>
<p>The <code>ol</code> element <span>represents</span> a list of
items, where the items have been intentionally ordered, such that
changing the order would change the meaning of the document.</p>
<p>The items of the list are the <code>li</code> element child nodes
of the <code>ol</code> element, in <span>tree order</span>.</p>
<p>The <dfn title="attr-ol-reversed"><code>reversed</code></dfn>
attribute is a <span>boolean attribute</span>. If present, it
indicates that the list is a descending list (..., 3, 2, 1). If the
attribute is omitted, the list is an ascending list (1, 2, 3,
...).</p>
<p>The <dfn title="attr-ol-start"><code>start</code></dfn>
attribute, if present, must be a <span>valid integer</span> giving
the ordinal value of the first list item.</p>
<div class="impl">
<p>If the <code title="attr-ol-start">start</code> attribute is
present, user agents must <span title="rules for parsing
integers">parse it as an integer</span>, in order to determine the
attribute's value. The default value, used if the attribute is
missing or if the value cannot be converted to a number according to
the referenced algorithm, is 1 if the element has no <code
title="attr-ol-reversed">reversed</code> attribute, and is the
number of child <code>li</code> elements otherwise.</p>
<p>The first item in the list has the ordinal value given by the
<code>ol</code> element's <code title="attr-ol-start">start</code>
attribute, unless that <code>li</code> element has a <code
title="attr-li-value">value</code> attribute with a value that can
be successfully parsed, in which case it has the ordinal value given
by that <code title="attr-li-value">value</code> attribute.</p>
<p>Each subsequent item in the list has the ordinal value given by
its <code title="attr-li-value">value</code> attribute, if it has
one, or, if it doesn't, the ordinal value of the previous item, plus
one if the <code title="attr-ol-reversed">reversed</code> is absent,
or minus one if it is present.</p>
<p>The <dfn title="dom-ol-reversed"><code>reversed</code></dfn> IDL
attribute must <span>reflect</span> the value of the <code
title="attr-ol-reversed">reversed</code> content attribute.</p>
<p>The <dfn title="dom-ol-start"><code>start</code></dfn> IDL
attribute must <span>reflect</span> the value of the <code
title="attr-ol-start">start</code> content attribute.</p>
</div>
<!-- v2: resuming numbering of lists from previous lists? -->
<div class="example">
<p>The following markup shows a list where the order matters, and
where the <code>ol</code> element is therefore appropriate. Compare
this list to the equivalent list in the <code>ul</code> section to
see an example of the same items using the <code>ul</code>
element.</p>
<pre><p>I have lived in the following countries (given in the order of when
I first lived there):</p>
<ol>
<li>Switzerland
<li>United Kingdom
<li>United States
<li>Norway
</ol></pre>
<p>Note how changing the order of the list changes the meaning of
the document. In the following example, changing the relative order
of the first two items has changed the birthplace of the
author:</p>
<pre><p>I have lived in the following countries (given in the order of when
I first lived there):</p>
<ol>
<li>United Kingdom
<li>Switzerland
<li>United States
<li>Norway
</ol></pre>
</div>
<h4>The <dfn><code>ul</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>li</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLUListElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>ul</code> element <span>represents</span> a list of
items, where the order of the items is not important — that
is, where changing the order would not materially change the meaning
of the document.</p>
<p>The items of the list are the <code>li</code> element child nodes
of the <code>ul</code> element.</p>
<div class="example">
<p>The following markup shows a list where the order does not
matter, and where the <code>ul</code> element is therefore
appropriate. Compare this list to the equivalent list in the
<code>ol</code> section to see an example of the same items using
the <code>ol</code> element.</p>
<pre><p>I have lived in the following countries:</p>
<ul>
<li>Norway
<li>Switzerland
<li>United Kingdom
<li>United States
</ul></pre>
<p>Note that changing the order of the list does not change the
meaning of the document. The items in the snippet above are given
in alphabetical order, but in the snippet below they are given in
order of the size of their current account balance in 2007, without
changing the meaning of the document whatsoever:</p>
<pre><p>I have lived in the following countries:</p>
<ul>
<li>Switzerland
<li>Norway
<li>United Kingdom
<li>United States
</ul></pre>
</div>
<h4>The <dfn><code>li</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Inside <code>ol</code> elements.</dd>
<dd>Inside <code>ul</code> elements.</dd>
<dd>Inside <code>menu</code> elements.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd>If the element is a child of an <code>ol</code> element: <code title="attr-li-value">value</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLLIElement</dfn> : <span>HTMLElement</span> {
attribute long <span title="dom-li-value">value</span>;
};</pre>
</dd>
</dl>
<p>The <code>li</code> element <span>represents</span> a list
item. If its parent element is an <code>ol</code>, <code>ul</code>,
or <code>menu</code> element, then the element is an item of the
parent element's list, as defined for those elements. Otherwise, the
list item has no defined list-related relationship to any other
<code>li</code> element.</p>
<p>The <dfn title="attr-li-value"><code>value</code></dfn>
attribute, if present, must be a <span>valid integer</span> giving
the ordinal value of the list item.</p>
<div class="impl">
<p>If the <code title="attr-li-value">value</code> attribute is
present, user agents must <span title="rules for parsing
integers">parse it as an integer</span>, in order to determine the
attribute's value. If the attribute's value cannot be converted to a
number, the attribute must be treated as if it was absent. The
attribute has no default value.</p>
<p>The <code title="attr-li-value">value</code> attribute is
processed relative to the element's parent <code>ol</code> element
(q.v.), if there is one. If there is not, the attribute has no
effect.</p>
<p>The <dfn title="dom-li-value"><code>value</code></dfn> IDL
attribute must <span>reflect</span> the value of the <code
title="dom-li-value">value</code> content attribute.</p>
</div>
<div class="example">
<p>The following example, the top ten movies are listed (in reverse
order). Note the way the list is given a title by using a
<code>figure</code> element and its <code>dt</code> element.</p>
<pre><figure>
<dt>The top 10 movies of all time</dt>
<dd>
<ol>
<li value="10"><cite>Josie and the Pussycats</cite>, 2001</li>
<li value="9"><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
<li value="8"><cite>A Bug's Life</cite>, 1998</li>
<li value="7"><cite>Toy Story</cite>, 1995</li>
<li value="6"><cite>Monsters, Inc</cite>, 2001</li>
<li value="5"><cite>Cars</cite>, 2006</li>
<li value="4"><cite>Toy Story 2</cite>, 1999</li>
<li value="3"><cite>Finding Nemo</cite>, 2003</li>
<li value="2"><cite>The Incredibles</cite>, 2004</li>
<li value="1"><cite>Ratatouille</cite>, 2007</li>
</ol>
<dd>
</figure></pre>
<p>The markup could also be written as follows, using the <code
title="attr-ol-reversed">reversed</code> attribute on the
<code>ol</code> element:</p>
<pre><figure>
<dt>The top 10 movies of all time</dt>
<dd>
<ol reversed>
<li><cite>Josie and the Pussycats</cite>, 2001</li>
<li><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
<li><cite>A Bug's Life</cite>, 1998</li>
<li><cite>Toy Story</cite>, 1995</li>
<li><cite>Monsters, Inc</cite>, 2001</li>
<li><cite>Cars</cite>, 2006</li>
<li><cite>Toy Story 2</cite>, 1999</li>
<li><cite>Finding Nemo</cite>, 2003</li>
<li><cite>The Incredibles</cite>, 2004</li>
<li><cite>Ratatouille</cite>, 2007</li>
</ol>
</dd>
</figure></pre>
</div>
<p class="note">If the <code>li</code> element is the child of a
<code>menu</code> element and itself has a child that defines a
<span title="concept-command">command</span>, then the
<code>li</code> element will match the <code
title="selector-enabled">:enabled</code> and <code
title="selector-disabled">:disabled</code> pseudo-classes in the
same way as the first such child element does.</p>
<h4>The <dfn><code>dl</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Zero or more groups each consisting of one or more
<code>dt</code> elements followed by one or more <code>dd</code>
elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLDListElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>dl</code> element <span>represents</span> an
association list consisting of zero or more name-value groups (a
description list). Each group must consist of one or more names
(<code>dt</code> elements) followed by one or more values
(<code>dd</code> elements). Within a single <code>dl</code> element,
there should not be more than one <code>dt</code> element for each
name.</p>
<p>Name-value groups may be terms and definitions, metadata topics
and values, or any other groups of name-value data.</p>
<p>The values within a group are alternatives; multiple paragraphs
forming part of the same value must all be given within the same
<code>dd</code> element.</p>
<p>The order of the list of groups, and of the names and values
within each group, may be significant.</p>
<div class="impl">
<p>If a <code>dl</code> element is empty, it contains no groups.</p>
<p>If a <code>dl</code> element contains non-<span
title="inter-element whitespace">whitespace</span> <span title="text
node">text nodes</span>, or elements other than <code>dt</code> and
<code>dd</code>, then those elements or <span title="text node">text
nodes</span> do not form part of any groups in that
<code>dl</code>.</p>
<p>If a <code>dl</code> element contains only <code>dt</code>
elements, then it consists of one group with names but no
values.</p>
<p>If a <code>dl</code> element contains only <code>dd</code>
elements, then it consists of one group with values but no
names.</p>
<p>If a <code>dl</code> element starts with one or more
<code>dd</code> elements, then the first group has no associated
name.</p>
<p>If a <code>dl</code> element ends with one or more
<code>dt</code> elements, then the last group has no associated
value.</p>
<p class="note">When a <code>dl</code> element doesn't match its
content model, it is often due to accidentally using <code>dd</code>
elements in the place of <code>dt</code> elements and vice
versa. Conformance checkers can spot such mistakes and might be able
to advise authors how to correctly use the markup.</p>
</div>
<div class="example">
<p>In the following example, one entry ("Authors") is linked to two
values ("John" and "Luke").</p>
<pre><dl>
<dt> Authors
<dd> John
<dd> Luke
<dt> Editor
<dd> Frank
</dl></pre>
</div>
<div class="example">
<p>In the following example, one definition is linked to two
terms.</p>
<pre><dl>
<dt lang="en-US"> <dfn>color</dfn> </dt>
<dt lang="en-GB"> <dfn>colour</dfn> </dt>
<dd> A sensation which (in humans) derives from the ability of
the fine structure of the eye to distinguish three differently
filtered analyses of a view. </dd>
</dl></pre>
</div>
<div class="example">
<p>The following example illustrates the use of the <code>dl</code>
element to mark up metadata of sorts. At the end of the example,
one group has two metadata labels ("Authors" and "Editors") and two
values ("Robert Rothman" and "Daniel Jackson").</p>
<pre><dl>
<dt> Last modified time </dt>
<dd> 2004-12-23T23:33Z </dd>
<dt> Recommended update interval </dt>
<dd> 60s </dd>
<dt> Authors </dt>
<dt> Editors </dt>
<dd> Robert Rothman </dd>
<dd> Daniel Jackson </dd>
</dl></pre>
</div>
<div class="example">
<p>The following example shows the <code>dl</code> element used to
give a set of instructions. The order of the instructions here is
important (in the other examples, the order of the blocks was not
important).</p>
<pre><p>Determine the victory points as follows (use the
first matching case):</p>
<dl>
<dt> If you have exactly five gold coins </dt>
<dd> You get five victory points </dd>
<dt> If you have one or more gold coins, and you have one or more silver coins </dt>
<dd> You get two victory points </dd>
<dt> If you have one or more silver coins </dt>
<dd> You get one victory point </dd>
<dt> Otherwise </dt>
<dd> You get no victory points </dd>
</dl></pre>
</div>
<div class="example">
<p>The following snippet shows a <code>dl</code> element being used
as a glossary. Note the use of <code>dfn</code> to indicate the
word being defined.</p>
<pre><dl>
<dt><dfn>Apartment</dfn>, n.</dt>
<dd>An execution context grouping one or more threads with one or
more COM objects.</dd>
<dt><dfn>Flat</dfn>, n.</dt>
<dd>A deflated tire.</dd>
<dt><dfn>Home</dfn>, n.</dt>
<dd>The user's login directory.</dd>
</dl></pre>
</div>
<p class="note">The <code>dl</code> element is inappropriate for
marking up dialogue. <a href="#conversations">Examples of how to
mark up dialogue</a> are shown below.</p>
<h4>The <dfn><code>dt</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Before <code>dd</code> or <code>dt</code> elements inside <code>dl</code> elements.</dd>
<dd>In a <code>figure</code> element containing no other <code>dt</code> element children.</dd>
<dd>As the first child of a <code>details</code> element.</dd>
<dt>Content model:</dt>
<dd>When the parent node is a <code>figure</code> element: <span>flow content</span>, but with no descendant <code>figure</code> elements.</dd>
<dd>Otherwise: <span>phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>dt</code> element <span>represents</span> either: the
term, or name, part of a term-description group in a description
list (<code>dl</code> element); or, the caption of a
<code>figure</code> element; or, the summary of a
<code>details</code> element.</p>
<p class="note">The <code>dt</code> element itself, when used in a
<code>dl</code> element, does not indicate that its contents are a
term being defined, but this can be indicated using the
<code>dfn</code> element.</p>
<h4>The <dfn><code>dd</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>After <code>dt</code> or <code>dd</code> elements inside <code>dl</code> elements.</dd>
<dd>In a <code>figure</code> element containing no other <code>dd</code> element children.</dd>
<dd>As the last child of a <code>details</code> element.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>dd</code> element <span>represents</span> either: the
description, definition, or value, part of a term-description group
in a description list (<code>dl</code> element); or, the data of a
<code>figure</code> element; or, the details of a
<code>details</code> element.</p>
<div class="example">
<p>A <code>dl</code> can be used to define a vocabulary list, like
in a dictionary. In the following example, each entry, given by a
<code>dt</code> with a <code>dfn</code>, has several
<code>dd</code>s, showing the various parts of the definition.</p>
<!-- the actual pronunciations below are nonsense. -->
<pre><dl>
<dt><dfn>happiness</dfn></dt>
<dd class="pronunciation">/'hæ p. nes/</dd>
<dd class="part-of-speech"><i><abbr>n.</abbr></i></dd>
<dd>The state of being happy.</dd>
<dd>Good fortune; success. <q>Oh <b>happiness</b>! It worked!</q></dd>
<dt><dfn>rejoice</dfn></dt>
<dd class="pronunciation">/ri jois'/</dd>
<dd><i class="part-of-speech"><abbr>v.intr.</abbr></i> To be delighted oneself.</dd>
<dd><i class="part-of-speech"><abbr>v.tr.</abbr></i> To cause one to be delighted.</dd>
</dl></pre>
</div>
<h4>The <dfn><code>div</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span><code title="">formatBlock</code> candidate</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLDivElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>div</code> element has no special meaning at all. It
<span>represents</span> its children. It can be used with the <code
title="attr-class">class</code>, <code
title="attr-lang">lang</code>, and <code
title="attr-title">title</code> attributes to mark up semantics
common to a group of consecutive elements.</p>
<p class="note">Authors are strongly encouraged to view the
<code>div</code> element as an element of last resort, for when no
other element is suitable. Use of the <code>div</code> element
instead of more appropriate elements leads to poor accessibility for
readers and poor maintainability for authors.</p>
<div class="example">
<p>For example, a blog post would be marked up using
<code>article</code>, a chapter using <code>section</code>, a
page's navigation aids using <code>nav</code>, and a group of form
controls using <code>fieldset</code>.</p>
<p>On the other hand, <code>div</code> elements can be useful for
stylistic purposes or to wrap multiple paragraphs within a section
that are all to be annotated in a similar way. In the following
example, we see <code>div</code> elements used as a way to set the
language of two paragraphs at once, instead of setting the language
on the two paragraph elements separately:</p>
<pre><article lang="en-US">
<h1>My use of language and my cats</h1>
<p>My cat's behavior hasn't changed much since her absence, except
that she plays her new physique to the neighbors regularly, in an
attempt to get pets.</p>
<div lang="en-GB">
<p>My other cat, coloured black and white, is a sweetie. He followed
us to the pool today, walking down the pavement with us. Yesterday
he apparently visited our neighbours. I wonder if he recognises that
their flat is a mirror image of ours.</p>
<p>Hm, I just noticed that in the last paragraph I used British
English. But I'm supposed to write in American English. So I
shouldn't say "pavement" or "flat" or "colour"...</p>
</div>
<p>I should say "sidewalk" and "apartment" and "color"!</p>
</article></pre>
</div>
<h3>Text-level semantics</h3>
<h4>The <dfn><code>a</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd>When the element only contains <span>phrasing content</span>: <span>phrasing content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Transparent</span>, but there must be no <span>interactive content</span> descendant.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-hyperlink-href">href</code></dd>
<dd><code title="attr-hyperlink-target">target</code></dd>
<dd><code title="attr-hyperlink-ping">ping</code></dd>
<dd><code title="attr-hyperlink-rel">rel</code></dd>
<dd><code title="attr-hyperlink-media">media</code></dd>
<dd><code title="attr-hyperlink-hreflang">hreflang</code></dd>
<dd><code title="attr-hyperlink-type">type</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLAnchorElement</dfn> : <span>HTMLElement</span> {
stringifier attribute DOMString <span title="dom-a-href">href</span>;
attribute DOMString <span title="dom-a-target">target</span>;
attribute DOMString <span title="dom-a-ping">ping</span>;
attribute DOMString <span title="dom-a-rel">rel</span>;
readonly attribute DOMTokenList <span title="dom-a-relList">relList</span>;
attribute DOMString <span title="dom-a-media">media</span>;
attribute DOMString <span title="dom-a-hreflang">hreflang</span>;
attribute DOMString <span title="dom-a-type">type</span>;
// <span>URL decomposition IDL attributes</span>
attribute DOMString <span title="dom-a-protocol">protocol</span>;
attribute DOMString <span title="dom-a-host">host</span>;
attribute DOMString <span title="dom-a-hostname">hostname</span>;
attribute DOMString <span title="dom-a-port">port</span>;
attribute DOMString <span title="dom-a-pathname">pathname</span>;
attribute DOMString <span title="dom-a-search">search</span>;
attribute DOMString <span title="dom-a-hash">hash</span>;
};</pre>
</dd>
</dl>
<p>If the <code>a</code> element has an <code
title="attr-hyperlink-href">href</code> attribute, then it
<span>represents</span> a <span>hyperlink</span> (a hypertext
anchor).</p>
<!-- v2: Eric Meyer requests the ability to nest links so that a big
hyperlink, e.g. representing a calendar event, can be clickable,
while within it there are subareas that represent links to distinct
areas, e.g. a link to see photos of the event, or to edit the event,
or some such. -->
<p>If the <code>a</code> element has no <code
title="attr-hyperlink-href">href</code> attribute, then the element
<span>represents</span> a placeholder for where a link might
otherwise have been placed, if it had been relevant.</p>
<p>The <code title="attr-hyperlink-target">target</code>, <code
title="attr-hyperlink-ping">ping</code>, <code
title="attr-hyperlink-rel">rel</code>, <code
title="attr-hyperlink-media">media</code>, <code
title="attr-hyperlink-hreflang">hreflang</code>, and <code
title="attr-hyperlink-type">type</code> attributes must be omitted
if the <code title="attr-hyperlink-href">href</code> attribute is
not present.</p>
<div class="example">
<p>If a site uses a consistent navigation toolbar on every page,
then the link that would normally link to the page itself could be
marked up using an <code>a</code> element:</p>
<pre><nav>
<ul>
<li> <a href="/">Home</a> </li>
<li> <a href="/news">News</a> </li>
<li> <a>Examples</a> </li>
<li> <a href="/legal">Legal</a> </li>
</ul>
</nav></pre>
</div>
<div class="impl">
<p>The <code title="attr-hyperlink-href">href</code>, <code
title="attr-hyperlink-target">target</code> and <code
title="attr-hyperlink-ping">ping</code> attributes affect what
happens when users <span title="following hyperlinks">follow
hyperlinks</span> created using the <code>a</code> element. The
<code title="attr-hyperlink-rel">rel</code>, <code
title="attr-hyperlink-media">media</code>, <code
title="attr-hyperlink-hreflang">hreflang</code>, and <code
title="attr-hyperlink-type">type</code> attributes may be used to
indicate to the user the likely nature of the target resource before
the user follows the link.</p>
<p>The <span>activation behavior</span> of <code>a</code> elements
that represent <span title="hyperlink">hyperlinks</span> is to run
the following steps:</p>
<ol>
<li><p>If the <code title="event-DOMActivate">DOMActivate</code>
event in question is not <span
title="concept-events-trusted">trusted</span> (i.e. a <code
title="dom-click">click()</code> method call was the reason for the
event being dispatched), and the <code>a</code> element's <code
title="attr-hyperlink-target">target</code> attribute is such that
applying <span>the rules for choosing a browsing context given a
browsing context name</span>, using the value of the <code
title="attr-hyperlink-target">target</code> attribute as the
browsing context name, would result in there not being a chosen
browsing context, then raise an <code>INVALID_ACCESS_ERR</code>
exception and abort these steps.</p></li>
<li><p>If the target of the <code title="event-click">click</code>
event is an <code>img</code> element with an <code
title="attr-img-ismap">ismap</code> attribute specified, then
server-side image map processing must be performed, as follows:</p>
<ol>
<!-- http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E%0A...%3Ca%20href%3D%22%23%22%3E%3Cimg%20ismap%20usemap%3D%22%23a%22%20src%3D/resources/images/smallcats%3E%3C/a%3E%0A%3Cmap%20name%3Da%3E%3Carea%20shape%3Drect%20coords%3D0%2C0%2C50%2C50%20href%3Db%3E%3C/map%3E -->
<li>If the <code title="event-DOMActivate">DOMActivate</code>
event was dispatched as the result of a real
pointing-device-triggered <code title="event-click">click</code>
event on the <code>img</code> element, then let <var
title="">x</var> be the distance in CSS pixels from the left edge
of the image's left border, if it has one, or the left edge of
the image otherwise, to the location of the click, and let <var
title="">y</var> be the distance in CSS pixels from the top edge
of the image's top border, if it has one, or the top edge of the
image otherwise, to the location of the click. Otherwise, let
<var title="">x</var> and <var title="">y</var> be zero.</li>
<li>Let the <dfn><var>hyperlink suffix</var></dfn> be a U+003F
QUESTION MARK character, the value of <var title="">x</var>
expressed as a base-ten integer using ASCII digits, a U+002C
COMMA character (,), and the value of <var title="">y</var>
expressed as a base-ten integer using ASCII digits. ASCII digits
are the characters in the range U+0030 DIGIT ZERO (0) to U+0039
DIGIT NINE (9).</li>
</ol>
</li>
<li><p>Finally, the user agent must <span title="following
hyperlinks">follow the hyperlink</span> defined by the
<code>a</code> element. If the steps above defined a <var>hyperlink
suffix</var>, then take that into account when following the
hyperlink.</p></li>
</ol>
<p>The IDL attributes <dfn
title="dom-a-href"><code>href</code></dfn>, <dfn
title="dom-a-ping"><code>ping</code></dfn>, <dfn
title="dom-a-target"><code>target</code></dfn>, <dfn
title="dom-a-rel"><code>rel</code></dfn>, <dfn
title="dom-a-media"><code>media</code></dfn>, <dfn
title="dom-a-hreflang"><code>hreflang</code></dfn>, and <dfn
title="dom-a-type"><code>type</code></dfn>, must
<span>reflect</span> the respective content attributes of the same
name.</p>
<p>The IDL attribute <dfn
title="dom-a-rellist"><code>relList</code></dfn> must
<span>reflect</span> the <code title="attr-hyperlink-rel">rel</code>
content attribute.</p>
<p>The <code>a</code> element also supports the complement of
<span>URL decomposition IDL attributes</span>, <dfn
title="dom-a-protocol"><code>protocol</code></dfn>, <dfn
title="dom-a-host"><code>host</code></dfn>, <dfn
title="dom-a-port"><code>port</code></dfn>, <dfn
title="dom-a-hostname"><code>hostname</code></dfn>, <dfn
title="dom-a-pathname"><code>pathname</code></dfn>, <dfn
title="dom-a-search"><code>search</code></dfn>, and <dfn
title="dom-a-hash"><code>hash</code></dfn>. These must follow the
rules given for URL decomposition IDL attributes, with the <span
title="concept-uda-input">input</span> being the result of <span
title="resolve a url">resolving</span> the element's <code
title="attr-hyperlink-href">href</code> attribute relative to the
element, if there is such an attribute and resolving it is
successful, or the empty string otherwise; and the <span
title="concept-uda-setter">common setter action</span> being the
same as setting the element's <code
title="attr-hyperlink-href">href</code> attribute to the new output
value.</p>
</div>
<div class="example">
<p>The <code>a</code> element may be wrapped around entire
paragraphs, lists, tables, and so forth, even entire sections, so
long as there is no interactive content within (e.g. buttons or
other links). This example shows how this can be used to make an
entire advertising block into a link:</p>
<pre><aside class="advertising">
<h1>Advertising</h1>
<a href="http://ad.example.com/?adid=1929&amp;pubid=1422">
<section>
<h1>Mellblomatic 9000!</h1>
<p>Turn all your widgets into mellbloms!</p>
<p>Only $9.99 plus shipping and handling.</p>
</section>
</a>
<a href="http://ad.example.com/?adid=375&amp;pubid=1422">
<section>
<h1>The Mellblom Browser</h1>
<p>Web browsing at the speed of light.</p>
<p>No other browser goes faster!</p>
</section>
</a>
</aside></pre>
</div>
<h4>The <dfn><code>em</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>em</code> element <span>represents</span> stress
emphasis of its contents.</p>
<p>The level of emphasis that a particular piece of content has is
given by its number of ancestor <code>em</code> elements.</p>
<p>The placement of emphasis changes the meaning of the sentence.
The element thus forms an integral part of the content. The precise
way in which emphasis is used in this way depends on the
language.</p>
<div class="example">
<p>These examples show how changing the emphasis changes the
meaning. First, a general statement of fact, with no emphasis:</p>
<pre><p>Cats are cute animals.</p></pre>
<p>By emphasizing the first word, the statement implies that the
kind of animal under discussion is in question (maybe someone is
asserting that dogs are cute):</p>
<pre><p><em>Cats</em> are cute animals.</p></pre>
<p>Moving the emphasis to the verb, one highlights that the truth
of the entire sentence is in question (maybe someone is saying cats
are not cute):</p>
<pre><p>Cats <em>are</em> cute animals.</p></pre>
<p>By moving it to the adjective, the exact nature of the cats
is reasserted (maybe someone suggested cats were <em>mean</em>
animals):</p>
<pre><p>Cats are <em>cute</em> animals.</p></pre>
<p>Similarly, if someone asserted that cats were vegetables,
someone correcting this might emphasize the last word:</p>
<pre><p>Cats are cute <em>animals</em>.</p></pre>
<p>By emphasizing the entire sentence, it becomes clear that the
speaker is fighting hard to get the point across. This kind of
emphasis also typically affects the punctuation, hence the
exclamation mark here.</p>
<pre><p><em>Cats are cute animals!</em></p></pre>
<p>Anger mixed with emphasizing the cuteness could lead to markup
such as:</p>
<pre><p><em>Cats are <em>cute</em> animals!</em></p></pre>
</div>
<div class="note">
<p>The <code>em</code> element isn't a generic "italics"
element. Sometimes, text is intended to stand out from the rest of
the paragraph, as if it was in a different mood or voice. For this,
the <code>i</code> element is more appropriate.</p>
<p>The <code>em</code> element also isn't intended to convey
importance; for that purpose, the <code>strong</code> element is
more appropriate.</p>
<!--
Thus the following is a bad use of <em>:
<p><em>Note</em>: ...</p>
You should use <strong> or <i> for this instead (depending on
exactly what you're doing).
-->
</div>
<h4>The <dfn><code>strong</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>strong</code> element <span>represents</span> strong
importance for its contents.</p>
<p>The relative level of importance of a piece of content is given
by its number of ancestor <code>strong</code> elements; each
<code>strong</code> element increases the importance of its
contents.</p>
<p>Changing the importance of a piece of text with the
<code>strong</code> element does not change the meaning of the
sentence.</p>
<div class="example">
<p>Here is an example of a warning notice in a game, with the
various parts marked up according to how important they are:</p>
<!-- DO NOT REFLOW THIS EXAMPLE it has been carefully balanced -->
<pre><p><strong>Warning.</strong> This dungeon is dangerous.
<strong>Avoid the ducks.</strong> Take any gold you find.
<strong><strong>Do not take any of the diamonds</strong>,
they are explosive and <strong>will destroy anything within
ten meters.</strong></strong> You have been warned.</p></pre>
</div>
<h4>The <dfn><code>small</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>small</code> element <span>represents</span> side
comments such as small print.</p>
<p class="note">Small print typically features disclaimers, caveats,
legal restrictions, or copyrights. Small print is also sometimes
used for attribution, or for satisfying licensing requirements.</p>
<p class="note">The <code>small</code> element does not
"de-emphasize" or lower the importance of text emphasized by the
<code>em</code> element or marked as important with the
<code>strong</code> element.</p>
<p>The <code>small</code> element should not be used for extended
spans of text, such as multiple paragraphs, lists, or sections of
text. It is only intended for short runs of text. The text of a page
listing terms of use, for instance, would not be a suitable
candidate for the <code>small</code> element: in such a case, the
text is not a side comment, it is the main content of the page.</p>
<div class="example">
<p>In this example the footer contains contact information and a
copyright notice.</p>
<pre><footer>
<address>
For more details, contact
<a href="mailto:js@example.com">John Smith</a>.
</address>
<p><small>© copyright 2038 Example Corp.</small></p>
</footer></pre>
</div>
<div class="example">
<p>In this second example, the <code>small</code> element is used
for a side comment in an article.</p>
<pre><p>Example Corp today announced record profits for the
second quarter <small>(Full Disclosure: Foo News is a subsidiary of
Example Corp)</small>, leading to speculation about a third quarter
merger with Demo Group.</p></pre>
<p>This is distinct from a sidebar, which might be multiple
paragraphs long and is removed from the main flow of text. In the
following example, we see a sidebar from the same article. This
sidebar also has small print, indicating the source of the
information in the sidebar.</p>
<pre><aside>
<h1>Example Corp</h1>
<p>This company mostly creates small software and Web
sites.</p>
<p>The Example Corp company mission is "To provide entertainment
and news on a sample basis".</p>
<p><small>Information obtained from <a
href="http://example.com/about.html">example.com</a> home
page.</small></p>
</aside></pre>
</div>
<div class="example">
<p>In this last example, the <code>small</code> element is marked
as being <em>important</em> small print.</p>
<pre><p><strong><small>Continued use of this service will result in a kiss.</small></strong></p></pre>
</div>
<h4>The <dfn><code>cite</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>cite</code> element <span>represents</span> the title
of a work (e.g.
a book,
a paper,
an essay,
a poem,
a score,
a song,
a script,
a film,
a TV show,
a game,
a sculpture,
a painting,
a theatre production,
a play,
an opera,
a musical,
an exhibition,
a legal case report,
etc). This can be a work that is being quoted or
referenced in detail (i.e. a citation), or it can just be a work
that is mentioned in passing.</p>
<p>A person's name is not the title of a work — even if people
call that person a piece of work — and the element must
therefore not be used to mark up people's names. (In some cases, the
<code>b</code> element might be appropriate for names; e.g. in a
gossip article where the names of famous people are keywords
rendered with a different style to draw attention to them. In other
cases, if an element is <em>really</em> needed, the
<code>span</code> element can be used.)</p>
<!--(some people argue a ship is a work)
<p>A ship is similarly not a work, and the element must not be used
to mark up ship names (the <code>i</code> element can be used for
that purpose).</p>
-->
<div class="example">
<p>This next example shows a typical use of the <code>cite</code>
element:</p>
<pre><p>My favorite book is <cite>The Reality Dysfunction</cite> by
Peter F. Hamilton. My favorite comic is <cite>Pearls Before
Swine</cite> by Stephan Pastis. My favorite track is <cite>Jive
Samba</cite> by the Cannonball Adderley Sextet.</p></pre>
</div>
<div class="example">
<p>This is correct usage:</p>
<pre><p>According to the Wikipedia article <cite>HTML</cite>, as it
stood in mid-February 2008, leaving attribute values unquoted is
unsafe. This is obviously an over-simplification.</p></pre>
<p>The following, however, is incorrect usage, as the
<code>cite</code> element here is containing far more than the
title of the work:</p>
<pre class="bad"><!-- do not copy this example, it is an example of bad usage! -->
<p>According to <cite>the Wikipedia article on HTML</cite>, as it
stood in mid-February 2008, leaving attribute values unquoted is
unsafe. This is obviously an over-simplification.</p></pre>
</div>
<div class="example">
<p>The <code>cite</code> element is obviously a key part of any
citation in a bibliography, but it is only used to mark the
title:</p>
<pre><p><cite>Universal Declaration of Human Rights</cite>, United Nations,
December 1948. Adopted by General Assembly resolution 217 A (III).</p></pre>
</div>
<p class="note">A <em>citation</em> is not a <em>quote</em> (for
which the <code>q</code> element is appropriate).</p>
<div class="example">
<p>This is incorrect usage, because <code>cite</code> is not for
quotes:</p>
<pre><p><cite>This is wrong!</cite>, said Ian.</p></pre>
<p>This is also incorrect usage, because a person is not a
work:</p>
<pre><p><q>This is still wrong!</q>, said <cite>Ian</cite>.</p></pre>
<p>The correct usage does not use a <code>cite</code> element:</p>
<pre><p><q>This is correct</q>, said Ian.</p></pre>
<p>As mentioned above, the <code>b</code> element might be relevant
for marking names as being keywords in certain kinds of
documents:</p>
<pre><p>And then <b>Ian</b> said <q>this might be right, in a
gossip column, maybe!</q>.</p></pre>
</div>
<h4>The <dfn><code>q</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-q-cite">cite</code></dd>
<dt>DOM interface:</dt>
<dd>
The <code>q</code> element uses the <code>HTMLQuoteElement</code> interface.
</dd>
</dl>
<p>The <code>q</code> element <span>represents</span> some <span
title="phrasing content">phrasing content</span> quoted from another
source.</p>
<p>Quotation punctuation (such as quotation marks) that is quoting
the contents of the element must not appear immediately before,
after, or inside <code>q</code> elements; they will be inserted into
the rendering by the user agent.</p>
<p>Content inside a <code>q</code> element must be quoted from
another source, whose address, if it has one, should be cited in the
<dfn title="attr-q-cite"><code>cite</code></dfn> attribute. The
source may be fictional, as when quoting characters in a novel or
screenplay.</p>
<p>If the <code title="attr-q-cite">cite</code> attribute is
present, it must be a <span>valid URL</span>. <span class="impl">To
obtain the corresponding citation link, the value of the attribute
must be <span title="resolve a url">resolved</span> relative to the
element. User agents should allow users to follow such citation
links.</span></p>
<p>The <code>q</code> element must not be used in place of quotation
marks that do not represent quotes; for example, it is inappropriate
to use the <code>q</code> element for marking up sarcastic
statements.</p>
<p>The use of <code>q</code> elements to mark up quotations is
entirely optional; using explicit quotation punctuation without
<code>q</code> elements is just as correct.</p>
<div class="example">
<p>Here is a simple example of the use of the <code>q</code>
element:</p>
<pre><p>The man said <q>Things that are impossible just take
longer</q>. I disagreed with him.</p></pre>
</div>
<div class="example">
<p>Here is an example with both an explicit citation link in the
<code>q</code> element, and an explicit citation outside:</p>
<pre><p>The W3C page <cite>About W3C</cite> says the W3C's
mission is <q cite="http://www.w3.org/Consortium/">To lead the
World Wide Web to its full potential by developing protocols and
guidelines that ensure long-term growth for the Web</q>. I
disagree with this mission.</p></pre>
</div>
<div class="example">
<p>In the following example, the quotation itself contains a
quotation:</p>
<pre><p>In <cite>Example One</cite>, he writes <q>The man
said <q>Things that are impossible just take longer</q>. I
disagreed with him</q>. Well, I disagree even more!</p></pre>
</div>
<div class="example">
<p>In the following example, quotation marks are used instead of
the <code>q</code> element:</p>
<pre><p>His best argument was ❝I disagree❞, which
I thought was laughable.</p></pre>
</div>
<div class="example">
<p>In the following example, there is no quote — the
quotation marks are used to name a word. Use of the <code>q</code>
element in this case would be inappropriate.</p>
<pre><p>The word "ineffable" could have been used to describe the disaster
resulting from the campaign's mismanagement.</p></pre>
</div>
<h4>The <dfn><code>dfn</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>, but there must be no <code>dfn</code> element descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd>Also, the <code title="attr-dfn-title">title</code> attribute has special semantics on this element.</dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>dfn</code> element <span>represents</span> the defining
instance of a term. The <span title="paragraph">paragraph</span>,
<span title="dl">description list group</span>, or <span
title="sectioning content">section</span> that is the nearest
ancestor of the <code>dfn</code> element must also contain the
definition(s) for the <span title="defining term">term</span> given
by the <code>dfn</code> element.</p>
<p><dfn>Defining term</dfn>: If the <code>dfn</code> element has a
<dfn title="attr-dfn-title"><code>title</code></dfn> attribute, then
the exact value of that attribute is the term being defined.
Otherwise, if it contains exactly one element child node and no
child <span title="text node">text nodes</span>, and that child
element is an <code>abbr</code> element with a <code
title="attr-abbr-title">title</code> attribute, then the exact value
of <em>that</em> attribute is the term being defined. Otherwise, it
is the exact <code>textContent</code> of the <code>dfn</code>
element that gives the term being defined.</p>
<!-- note that this means <dfn>x \n x</dfn> won't match <span>x x</span> -->
<p>If the <code title="attr-dfn-title">title</code> attribute of the
<code>dfn</code> element is present, then it must contain only the
term being defined.</p>
<p class="note">The <code title="attr-title">title</code> attribute
of ancestor elements does not affect <code>dfn</code> elements.</p>
<p>An <code>a</code> element that links to a <code>dfn</code>
element represents an instance of the term defined by the
<code>dfn</code> element.</p>
<div class="example">
<p>In the following fragment, the term "GDO" is first defined in
the first paragraph, then used in the second.</p>
<pre><p>The <dfn><abbr title="Garage Door Opener">GDO</abbr></dfn>
is a device that allows off-world teams to open the iris.</p>
<!-- ... later in the document: -->
<p>Teal'c activated his <abbr title="Garage Door Opener">GDO</abbr>
and so Hammond ordered the iris to be opened.</p></pre>
<p>With the addition of an <code>a</code> element, the reference
can be made explicit:</p>
<pre><p>The <dfn id=gdo><abbr title="Garage Door Opener">GDO</abbr></dfn>
is a device that allows off-world teams to open the iris.</p>
<!-- ... later in the document: -->
<p>Teal'c activated his <a href=#gdo><abbr title="Garage Door Opener">GDO</abbr></a>
and so Hammond ordered the iris to be opened.</p></pre>
</div>
<h4>The <dfn><code>abbr</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd>Also, the <code title="attr-abbr-title">title</code> attribute has special semantics on this element.</dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>abbr</code> element <span>represents</span> an
abbreviation or acronym, optionally with its expansion. The <dfn
title="attr-abbr-title"><code>title</code></dfn> attribute may be
used to provide an expansion of the abbreviation. The attribute, if
specified, must contain an expansion of the abbreviation, and
nothing else.</p>
<div class="example">
<p>The paragraph below contains an abbreviation marked up with the
<code>abbr</code> element. This paragraph <span title="defining
term">defines the term</span> "Web Hypertext Application Technology
Working Group".</p>
<pre><p>The <dfn id=whatwg><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></dfn>
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p></pre>
<p>An alternative way to write this would be:</p>
<pre><p>The <dfn id=whatwg>Web Hypertext Application Technology
Working Group</dfn> (<abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr>)
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p></pre>
</div>
<div class="example">
<p>This paragraph has two abbreviations. Notice how only one is
defined; the other, with no expansion associated with it, does not
use the <code>abbr</code> element.</p>
<pre><p>The
<abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr>
started working on HTML5 in 2004.</p></pre>
</div>
<div class="example">
<p>This paragraph links an abbreviation to its definition.</p>
<pre><p>The <a href="#whatwg"><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></a>
community does not have much representation from Asia.</p></pre>
</div>
<div class="example">
<p>This paragraph marks up an abbreviation without giving an
expansion, possibly as a hook to apply styles for abbreviations
(e.g. smallcaps).</p>
<pre><p>Philip` and Dashiva both denied that they were going to
get the issue counts from past revisions of the specification to
backfill the <abbr>WHATWG</abbr> issue graph.</p></pre>
</div>
<p>If an abbreviation is pluralized, the expansion's grammatical
number (plural vs singular) must match the grammatical number of the
contents of the element.</p>
<div class="example">
<p>Here the plural is outside the element, so the expansion is in
the singular:</p>
<pre><p>Two <abbr title="Working Group">WG</abbr>s worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p></pre>
<p>Here the plural is inside the element, so the expansion is in
the plural:</p>
<pre><p>Two <abbr title="Working Groups">WGs</abbr> worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p></pre>
</div>
<p>Abbreviations do not have to be marked up using this element. It
is expected to be useful in the following cases:</p>
<ul>
<li>Abbreviations for which the author wants to give expansions,
where using the <code>abbr</code> element with a <code
title="attr-title">title</code> attribute is an alternative to
including the expansion inline (e.g. in parentheses).</li>
<li>Abbreviations that are likely to be unfamiliar to the
document's readers, for which authors are encouraged to either mark
up the abbreviation using a <code>abbr</code> element with a <code
title="attr-title">title</code> attribute or include the expansion
inline in the text the first time the abbreviation is used.</li>
<li>Abbreviations whose presence needs to be semantically
annotated, e.g. so that they can be identified from a style sheet
and given specific styles, for which the <code>abbr</code> element
can be used without a <code title="attr-title">title</code>
attribute.</li>
</ul>
<p title="note">Providing an expansion in a <code
title="attr-title">title</code> attribute once will not necessarily
cause other <code>abbr</code> elements in the same document with the
same contents but without a <code title="attr-title">title</code>
attribute to behave as if they had the same expansion. Every
<code>abbr</code> element is independent.</p>
<h4>The <dfn><code>time</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>, but there must be no <code>time</code> element descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-time-datetime">datetime</code></dd>
<dd><code title="attr-time-pubdate">pubdate</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTimeElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-time-datetime">dateTime</span>;
attribute boolean <span title="dom-time-pubDate">pubDate</span>;
readonly attribute <span>Date</span> <span title="dom-time-valueAsDate">valueAsDate</span>;
};</pre>
</dd>
</dl>
<p>The <code>time</code> element <span>represents</span> either a
time on a 24 hour clock, or a precise date in the proleptic
Gregorian calendar, optionally with a time and a time-zone
offset. <a href="#refsGREGORIAN">[GREGORIAN]</a></p>
<p>This element is intended as a way to encode modern dates and
times in a machine-readable way so that user agents can offer to add
them to the user's calendar. For example, adding birthday reminders
or scheduling events.</p>
<!-- it's also intended for restyling to local conventions
(2000-12-31 vs 31-12-2000 vs 12-31-2000), but CSS doesn't support
that yet. -->
<div class="note">
<p>The <code>time</code> element is not intended for encoding times
for which a precise date or time cannot be established. For
example, it would be inappropriate for encoding times like "one
millisecond after the big bang", "the early part of the Jurassic
period", or "a winter around 250 BCE".</p>
<p>For dates before the introduction of the Gregorian calendar,
authors are encouraged to not use the <code>time</code> element, or
else to be very careful about converting dates and times from the
period to the Gregorian calendar. This is complicated by the manner
in which the Gregorian calendar was phased in, which occurred at
different times in different countries, ranging from partway
through the 16th century all the way to early in the 20th.</p>
</div>
<p>The <dfn title="attr-time-pubdate"><code>pubdate</code></dfn>
attribute is a <span>boolean attribute</span>. If specified, it
indicates that the date and time given by the element is the
publication date and time of the nearest ancestor
<code>article</code> element, or, if the element has no ancestor
<code>article</code> element, of the document as a whole. If the
element has a <code title="attr-time-pubdate">pubdate</code>
attribute specified, then the element <i>needs a date</i>. For each
<code>article</code> element, there must no more than one
<code>time</code> element with a <code
title="attr-time-pubdate">pubdate</code> attribute whose nearest
ancestor is that <code>article</code> element. Furthermore, for each
<code>Document</code>, there must be no more than one
<code>time</code> element with a <code
title="attr-time-pubdate">pubdate</code> attribute that does not
have an ancestor <code>article</code> element.</p>
<p>The <dfn title="attr-time-datetime"><code>datetime</code></dfn>
attribute, if present, gives the date or time being
specified. Otherwise, the date or time is given by the element's
contents.</p>
<p>If the element <i>needs a date</i>, and the <code
title="attr-time-datetime">datetime</code> attribute is present,
then the attribute's value must be a <span>valid date string with
optional time</span>.</p>
<p>If the element <i>needs a date</i>, but the <code
title="attr-time-datetime">datetime</code> attribute is not present,
then the element's <code>textContent</code> must be a <span>valid
date string in content with optional time</span>.</p>
<p>If the element does not <i>need a date</i>, and the <code
title="attr-time-datetime">datetime</code> attribute is present,
then the attribute's value must be a <span>valid date or time
string</span>.</p>
<p>If the element does not <i>need a date</i>, but the <code
title="attr-time-datetime">datetime</code> attribute is not present,
then the element's <code>textContent</code> must be a <span>valid
date or time string in content</span>.</p>
<p>The date, if any, must be expressed using the Gregorian
calendar.</p>
<div class="impl">
<p>If the <code title="attr-time-datetime">datetime</code> attribute
is present, the user agent should convey the attribute's value to
the user when rendering the element.</p>
</div>
<div class="example">
<p>The <code>time</code> element can be used to encode dates, for
example in Microformats. The following shows a hypothetical way of
encoding an event using a variant on hCalendar that uses the
<code>time</code> element:</p>
<pre><div class="vevent">
<a class="url" href="http://www.web2con.com/">http://www.web2con.com/</a>
<span class="summary">Web 2.0 Conference</span>:
<time class="dtstart" datetime="2007-10-05">October 5</time> -
<time class="dtend" datetime="2007-10-20">19</time>,
at the <span class="location">Argent Hotel, San Francisco, CA</span>
</div></pre>
</div>
<div class="example">
<p>The <code>time</code> element is not necessary for encoding
dates or times. In the following snippet, the time is encoded using
<code>time</code>, so that it can be restyled (e.g. using XBL2) to
match local conventions, while the year is not marked up at all,
since marking it up would not be particularly useful.</p>
<pre><p>I usually have a snack at <time>16:00</time>.</p>
<p>I've liked model trains since at least 1983.</p></pre>
<p>Using a styling technology that supports restyling times, the
first paragraph from the above snippet could be rendered as follows:</p>
<blockquote><p>I usually have a snack at 4pm.</p></blockquote>
<p>Or it could be rendered as follows:</p>
<blockquote><p>I usually have a snack at 16h00.</p></blockquote>
</div>
<div class="impl">
<p>The <dfn title="dom-time-datetime"><code>dateTime</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-time-datetime">datetime</code> content attribute.</p>
<p>The <dfn title="dom-time-pubDate"><code>pubDate</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-time-pubdate">pubdate</code> content attribute.</p>
<p>User agents, to obtain the <dfn
title="concept-time-date">date</dfn>, <dfn
title="concept-time-time">time</dfn>, and <dfn
title="concept-time-timezone">time-zone offset</dfn> represented by
a <code>time</code> element, must follow these steps:</p>
<ol>
<li>If the <code title="attr-time-datetime">datetime</code>
attribute is present, then use the rules to <span>parse a date or
time string</span> with the flag <i>in attribute</i> from the value
of that attribute, and let the result be <var
title="">result</var>.</li>
<li>Otherwise, use the rules to <span>parse a date or time
string</span> with the flag <i>in content</i> from the element's
<code>textContent</code>, and let the result be <var
title="">result</var>.</li>
<li>If <var title="">result</var> is empty (because the parsing
failed), then the <span title="concept-time-date">date</span> is
unknown, the <span title="concept-time-time">time</span> is
unknown, and the <span title="concept-time-timezone">time-zone
offset</span> is unknown.</li>
<li>Otherwise: if <var title="">result</var> contains a date, then
that is the <span title="concept-time-date">date</span>; if <var
title="">result</var> contains a time, then that is the <span
title="concept-time-time">time</span>; and if <var
title="">result</var> contains a time-zone offset, then the
time-zone offset is the element's <span
title="concept-time-timezone">time-zone offset</span>. (A time-zone
offset can only be present if both a date and a time are also
present.)</li>
</ol>
</div>
<dl class="domintro">
<dt><var title="">time</var> . <code title="dom-time-valueAsDate">valueAsDate</code></dt>
<dd>
<p>Returns a <code>Date</code> object representing the specified date and time.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-time-valueAsDate"><code>valueAsDate</code></dfn> IDL
attribute must return either null or a new <code>Date</code> object
initialised to the relevant value as defined by the following
list:</p>
<dl>
<dt>If the <span title="concept-time-date">date</span> is known but
the <span title="concept-time-time">time</span> is not</dt>
<dd>The time corresponding to midnight UTC (i.e. the first second)
of the given <span title="concept-time-date">date</span>.</dd>
<dt>If the <span title="concept-time-time">time</span> is known but
the <span title="concept-time-date">date</span> is not</dt>
<dd>The time corresponding to the given <span
title="concept-time-time">time</span> of 1970-01-01, with the time
zone UTC.</dd>
<dt>If both the <span title="concept-time-date">date</span> and the
<span title="concept-time-time">time</span> are known</dt>
<dd>The time corresponding to the <span
title="concept-time-date">date</span> and <span
title="concept-time-time">time</span>, with the given <span
title="concept-time-timezone">time-zone offset</span>.</dd>
<dt>If neither the <span title="concept-time-date">date</span> nor
the <span title="concept-time-time">time</span> are known</dt>
<dd>The null value.</dd>
</dl>
<p>When a <code>Date</code> object is to be returned, a new one must
be constructed.</p> <!-- yes, this means .valueAsDate !=
.valueAsDate, but the object is mutable, so it'd be weird if we
didn't do that -->
</div>
<div class="example">
<p>In the following snippet:</p>
<pre><p>Our first date was <time datetime="2006-09-23">a Saturday</time>.</p></pre>
<p>...the <code>time</code> element's <code
title="dom-time-valueAsDate">valueAsDate</code> attribute would
have the value 1,158,969,600,000ms.</p>
</div>
<!-- <pre><p>We stopped talking at <time datetime="2006-09-24T05:00-07:00">5am the next morning</time>.</p></pre> -->
<div class="example">
<p>In the following snippet:</p>
<pre><p>Many people get up at <time>08:00</time>.</p></pre>
<p>...the <code>time</code> element's <code
title="dom-time-valueAsDate">valueAsDate</code> attribute would
have the value 28,800,000ms.</p>
</div>
<div class="example">
<p>In this example, an article's publication date is marked up
using <code>time</code>:</p>
<pre><article>
<h1>Small tasks</h1>
<footer>Published <time pubdate>2009-08-30</time>.</footer>
<p>I put a bike bell on his bike.</p>
</article></pre>
<p>Here is another way that could be marked up:</p>
<pre><article>
<h1>Small tasks</h1>
<footer>Published <time pubdate datetime="2009-08-30">today</time>.</footer>
<p>I put a bike bell on his bike.</p>
</article></pre>
<p>Here is the same thing but with the time included. Because the
element is empty, it will be replaced in the rendering with a
more readable version of the date and time given.</p>
<pre><article>
<h1>Small tasks</h1>
<footer>Published <time pubdate datetime="2009-08-30T07:13Z"></time>.</footer>
<p>I put a bike bell on his bike.</p>
</article></pre>
</div>
<h4>The <dfn><code>code</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>code</code> element <span>represents</span> a fragment
of computer code. This could be an XML element name, a filename, a
computer program, or any other string that a computer would
recognize.</p>
<p>Although there is no formal way to indicate the language of
computer code being marked up, authors who wish to mark
<code>code</code> elements with the language used, e.g. so that
syntax highlighting scripts can use the right rules, may do so by
adding a class prefixed with "<code title="">language-</code>" to
the element.</p>
<div class="example">
<p>The following example shows how the element can be used in a
paragraph to mark up element names and computer code, including
punctuation.</p>
<pre><p>The <code>code</code> element represents a fragment of computer
code.</p>
<p>When you call the <code>activate()</code> method on the
<code>robotSnowman</code> object, the eyes glow.</p>
<p>The example below uses the <code>begin</code> keyword to indicate
the start of a statement block. It is paired with an <code>end</code>
keyword, which is followed by the <code>.</code> punctuation character
(full stop) to indicate the end of the program.</p></pre>
</div>
<div class="example">
<p>The following example shows how a block of code could be marked
up using the <code>pre</code> and <code>code</code> elements.</p>
<pre><pre><code class="language-pascal">var i: Integer;
begin
i := 1;
end.</code></pre></pre>
<p>A class is used in that example to indicate the language
used.</p>
</div>
<p class="note">See the <code>pre</code> element for more details.</p>
<h4>The <dfn><code>var</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>var</code> element <span>represents</span> a
variable. This could be an actual variable in a mathematical
expression or programming context, or it could just be a term used
as a placeholder in prose.</p>
<div class="example">
<p>In the paragraph below, the letter "n" is being used as a
variable in prose:</p>
<pre><p>If there are <var>n</var> pipes leading to the ice
cream factory then I expect at <em>least</em> <var>n</var>
flavors of ice cream to be available for purchase!</p></pre>
</div>
<p>For mathematics, in particular for anything beyond the simplest
of expressions, MathML is more appropriate. However, the
<code>var</code> element can still be used to refer to specific
variables that are then mentioned in MathML expressions.</p>
<div class="example">
<p>In this example, an equation is shown, with a legend that
references the variables in the equation. The expression itself is
marked up with MathML, but the variables are mentioned in the
figure's legend using <code>var</code>.</p>
<pre><figure>
<dd>
<math>
<mi>a</mi>
<mo>=</mo>
<msqrt>
<msup><mi>b</mi><mn>2</mn></msup>
<mi>+</mi>
<msup><mi>c</mi><mn>2</mn></msup>
</msqrt>
</math>
</dd>
<dt>
Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of
a triangle with sides <var>b</var> and <var>c</var>
</dt>
</figure></pre>
</div>
<h4>The <dfn><code>samp</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>samp</code> element <span>represents</span> (sample)
output from a program or computing system.</p>
<p class="note">See the <code>pre</code> and <code>kbd</code>
elements for more details.</p>
<div class="example">
<p>This example shows the <code>samp</code> element being used
inline:</p>
<pre><p>The computer said <samp>Too much cheese in tray
two</samp> but I didn't know what that meant.</p></pre>
<p>This second example shows a block of sample output. Nested
<code>samp</code> and <code>kbd</code> elements allow for the
styling of specific elements of the sample output using a
style sheet.</p>
<pre><pre><samp><span class="prompt">jdoe@mowmow:~$</span> <kbd>ssh demo.example.com</kbd>
Last login: Tue Apr 12 09:10:17 2005 from mowmow.example.com on pts/1
Linux demo 2.6.10-grsec+gg3+e+fhs6b+nfs+gr0501+++p3+c4a+gr2b-reslog-v6.189 #1 SMP Tue Feb 1 11:22:36 PST 2005 i686 unknown
<span class="prompt">jdoe@demo:~$</span> <span class="cursor">_</span></samp></pre></pre>
</div>
<h4>The <dfn><code>kbd</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>kbd</code> element <span>represents</span> user input
(typically keyboard input, although it may also be used to represent
other input, such as voice commands).</p>
<p>When the <code>kbd</code> element is nested inside a
<code>samp</code> element, it represents the input as it was echoed
by the system.</p>
<p>When the <code>kbd</code> element <em>contains</em> a
<code>samp</code> element, it represents input based on system
output, for example invoking a menu item.</p>
<p>When the <code>kbd</code> element is nested inside another
<code>kbd</code> element, it represents an actual key or other
single unit of input as appropriate for the input mechanism.</p>
<div class="example">
<p>Here the <code>kbd</code> element is used to indicate keys to press:</p>
<pre><p>To make George eat an apple, press <kbd><kbd>Shift</kbd>+<kbd>F3</kbd></kbd></p></pre>
<p>In this second example, the user is told to pick a particular
menu item. The outer <code>kbd</code> element marks up a block of
input, with the inner <code>kbd</code> elements representing each
individual step of the input, and the <code>samp</code> elements
inside them indicating that the steps are input based on something
being displayed by the system, in this case menu labels:</p>
<pre><p>To make George eat an apple, select
<kbd><kbd><samp>File</samp></kbd>|<kbd><samp>Eat Apple...</samp></kbd></kbd>
</p></pre>
<p>Such precision isn't necessary; the following is equally fine:</p>
<pre><p>To make George eat an apple, select <kbd>File | Eat Apple...</kbd></p></pre>
</div>
<h4>The <dfn><code>sub</code></dfn> and <dfn><code>sup</code></dfn> elements</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which these elements may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Use <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>sup</code> element <span>represents</span> a
superscript and the <code>sub</code> element <span>represents</span>
a subscript.</p>
<p>These elements must be used only to mark up typographical
conventions with specific meanings, not for typographical
presentation for presentation's sake. For example, it would be
inappropriate for the <code>sub</code> and <code>sup</code> elements
to be used in the name of the LaTeX document preparation system. In
general, authors should use these elements only if the
<em>absence</em> of those elements would change the meaning of the
content.</p>
<p>In certain languages, superscripts are part of the typographical
conventions for some abbreviations.</p>
<div class="example">
<pre><p>The most beautiful women are
<span lang="fr"><abbr>M<sup>lle</sup></abbr> Gwendoline</span> and
<span lang="fr"><abbr>M<sup>me</sup></abbr> Denise</span>.</p></pre>
</div>
<p>The <code>sub</code> element can be used inside a
<code>var</code> element, for variables that have subscripts.</p>
<div class="example">
<p>Here, the <code>sub</code> element is used to represents the
subscript that identifies the variable in a family of
variables:</p>
<pre><p>The coordinate of the <var>i</var>th point is
(<var>x<sub><var>i</var></sub></var>, <var>y<sub><var>i</var></sub></var>).
For example, the 10th point has coordinate
(<var>x<sub>10</sub></var>, <var>y<sub>10</sub></var>).</p></pre>
</div>
<p>Mathematical expressions often use subscripts and superscripts.
Authors are encouraged to use MathML for marking up mathematics, but
authors may opt to use <code>sub</code> and <code>sup</code> if
detailed mathematical markup is not desired. <a
href="#refsMATHML">[MATHML]</a></p>
<div class="example">
<pre><var>E</var>=<var>m</var><var>c</var><sup>2</sup></pre>
<pre>f(<var>x</var>, <var>n</var>) = log<sub>4</sub><var>x</var><sup><var>n</var></sup></pre>
</div>
<h4>The <dfn><code>i</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>i</code> element <span>represents</span> a span of text
in an alternate voice or mood, or otherwise offset from the normal
prose, such as a taxonomic designation, a technical term, an
idiomatic phrase from another language, a thought, a ship name, or
some other prose whose typical typographic presentation is
italicized.</p>
<p>Terms in languages different from the main text should be
annotated with <code title="attr-lang">lang</code> attributes (or,
in XML, <span title="attr-xml-lang"><code title="">lang</code>
attributes in the <span>XML namespace</span></span>).</p>
<div class="example">
<p>The examples below show uses of the <code>i</code> element:</p>
<pre><p>The <i class="taxonomy">Felis silvestris catus</i> is cute.</p>
<p>The term <i>prose content</i> is defined above.</p>
<p>There is a certain <i lang="fr">je ne sais quoi</i> in the air.</p></pre>
<p>In the following example, a dream sequence is marked up using
<code>i</code> elements.</p>
<pre><p>Raymond tried to sleep.</p>
<p><i>The ship sailed away on Thursday</i>, he
dreamt. <i>The ship had many people aboard, including a beautiful
princess called Carey. He watched her, day-in, day-out, hoping she
would notice him, but she never did.</i></p>
<p><i>Finally one night he picked up the courage to speak with
her—</i></p>
<p>Raymond woke with a start as the fire alarm rang out.</p></pre>
</div>
<p>Authors are encouraged to use the <code
title="attr-class">class</code> attribute on the <code>i</code>
element to identify why the element is being used, so that if the
style of a particular use (e.g. dream sequences as opposed to
taxonomic terms) is to be changed at a later date, the author
doesn't have to go through the entire document (or series of related
documents) annotating each use. Similarly, authors are encouraged to
consider whether other elements might be more applicable than the
<code>i</code> element, for instance the <code>em</code> element for
marking up stress emphasis, or the <code>dfn</code> element to mark
up the defining instance of a term.</p>
<p class="note">Style sheets can be used to format <code>i</code>
elements, just like any other element can be restyled. Thus, it is
not the case that content in <code>i</code> elements will
necessarily be italicized.</p>
<h4>The <dfn><code>b</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>b</code> element <span>represents</span> a span of text
to be stylistically offset from the normal prose without conveying
any extra importance, such as key words in a document abstract,
product names in a review, or other spans of text whose typical
typographic presentation is boldened.</p>
<div class="example">
<p>The following example shows a use of the <code>b</code> element
to highlight key words without marking them up as important:</p>
<pre><p>The <b>frobonitor</b> and <b>barbinator</b> components are fried.</p></pre>
</div>
<div class="example">
<p>In the following example, objects in a text adventure are
highlighted as being special by use of the <code>b</code>
element.</p>
<pre><p>You enter a small room. Your <b>sword</b> glows
brighter. A <b>rat</b> scurries past the corner wall.</p></pre>
</div>
<div class="example">
<p>Another case where the <code>b</code> element is appropriate is
in marking up the lede (or lead) sentence or paragraph. The
following example shows how a <a
href="http://news.bbc.co.uk/2/hi/uk_news/scotland/north_east/7101506.stm">BBC
article about kittens adopting a rabbit as their own</a> could be
marked up:</p>
<pre><article>
<h2>Kittens 'adopted' by pet rabbit</h2>
<p><b>Six abandoned kittens have found an unexpected new
mother figure — a pet rabbit.</b></p>
<p>Veterinary nurse Melanie Humble took the three-week-old
kittens to her Aberdeen home.</p>
<i>[...]</i></pre>
</div>
<p>The <code>b</code> element should be used as a last resort when
no other element is more appropriate. In particular, headings should
use the <code>h1</code> to <code>h6</code> elements, stress emphasis
should use the <code>em</code> element, importance should be denoted
with the <code>strong</code> element, and text marked or highlighted
should use the <code>mark</code> element.</p>
<div class="example">
<p>The following would be <em>incorrect</em> usage:</p>
<pre class="bad"><p><b>WARNING!</b> Do not frob the barbinator!</p></pre>
<p>In the previous example, the correct element to use would have
been <code>strong</code>, not <code>b</code>.</p>
</div>
<p class="note">Style sheets can be used to format <code>b</code>
elements, just like any other element can be restyled. Thus, it is
not the case that content in <code>b</code> elements will
necessarily be boldened.</p>
<h4>The <dfn><code>mark</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<!-- v2: attribute that means "highlight this on the scrollbar" -->
<p>The <code>mark</code> element <span>represents</span> a run of
text in one document marked or highlighted for reference purposes,
due to its relevance in another context. When used in a quotation or
other block of text referred to from the prose, it indicates a
highlight that was not originally present but which has been added
to bring the reader's attention to a part of the text that might not
have been considered important by the original author when the block
was originally written, but which is now under previously unexpected
scrutiny. When used in the main prose of a document, it indicates a
part of the document that has been highlighted due to its likely
relevance to the user's current activity.</p>
<div class="example">
<p>This example shows how the <code>mark</code> element can be used
to bring attention to a particular part of a quotation:</p>
<pre><p lang="en-US">Consider the following quote:</p>
<blockquote lang="en-GB">
<p>Look around and you will find, no-one's really
<mark>colour</mark> blind.</p>
</blockquote>
<p lang="en-US">As we can tell from the <em>spelling</em> of the word,
the person writing this quote is clearly not American.</p></pre>
</div>
<div class="example">
<p>Another example of the <code>mark</code> element is highlighting
parts of a document that are matching some search string. If
someone looked at a document, and the server knew that the user was
searching for the word "kitten", then the server might return the
document with one paragraph modified as follows:</p>
<pre><p>I also have some <mark>kitten</mark>s who are visiting me
these days. They're really cute. I think they like my garden! Maybe I
should adopt a <mark>kitten</mark>.</p></pre>
</div>
<div class="example">
<p>In the following snippet, a paragraph of text refers to a
specific part of a code fragment.</p>
<pre><p>The highlighted part below is where the error lies:</p>
<pre><code>var i: Integer;
begin
i := <mark>1.1</mark>;
end.</code></pre></pre>
</div>
<div class="example">
<p>This is another example showing the use of <code>mark</code> to
highlight a part of quoted text that was originally not
emphasized. In this example, common typographic conventions have
led the author to explicitly style <code>mark</code> elements in
quotes to render in italics.</p>
<pre><article>
<style>
blockquote mark, q mark {
font: inherit; font-style: italic;
text-decoration: none;
background: transparent; color: inherit;
}
.bubble em {
font: inherit; font-size: larger;
text-decoration: underline;
}
</style>
<h1>She knew</h1>
<p>Did you notice the subtle joke in the joke on panel 4?</p>
<blockquote>
<p class="bubble">I didn't <em>want</em> to believe. <mark>Of course
on some level I realized it was a known-plaintext attack.</mark> But I
couldn't admit it until I saw for myself.</p>
</blockquote>
<p>(Emphasis mine.) I thought that was great. It's so pedantic, yet it
explains everything neatly.</p>
</article></pre>
<p>Note, incidentally, the distinction between the <code>em</code>
element in this example, which is part of the original text being
quoted, and the <code>mark</code> element, which is highlighting a
part for comment.</p>
</div>
<div class="example">
<p>The following example shows the difference between denoting the
<em>importance</em> of a span of text (<code>strong</code>) as
opposed to denoting the <em>relevance</em> of a span of text
(<code>mark</code>). It is an extract from a textbook, where the
extract has had the parts relevant to the exam highlighted. The
safety warnings, important though they may be, are apparently not
relevant to the exam.</p>
<pre><h3>Wormhole Physics Introduction</h3>
<p><mark>A wormhole in normal conditions can be held open for a
maximum of just under 39 minutes.</mark> Conditions that can increase
the time include a powerful energy source coupled to one or both of
the gates connecting the wormhole, and a large gravity well (such as a
black hole).</p>
<p><mark>Momentum is preserved across the wormhole. Electromagnetic
radiation can travel in both directions through a wormhole,
but matter cannot.</mark></p>
<p>When a wormhole is created, a vortex normally forms.
<strong>Warning: The vortex caused by the wormhole opening will
annihilate anything in its path.</strong> Vortexes can be avoided when
using sufficiently advanced dialing technology.</p>
<p><mark>An obstruction in a gate will prevent it from accepting a
wormhole connection.</mark></p></pre>
</div>
<h4>The <dfn><code>progress</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>, but there must be no <code>progress</code> element descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-progress-value">value</code></dd>
<dd><code title="attr-progress-max">max</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLProgressElement</dfn> : <span>HTMLElement</span> {
attribute float <span title="dom-progress-value">value</span>;
attribute float <span title="dom-progress-max">max</span>;
readonly attribute float <span title="dom-progress-position">position</span>;
};</pre>
</dd>
</dl>
<p>The <code>progress</code> element <span>represents</span> the
completion progress of a task. The progress is either indeterminate,
indicating that progress is being made but that it is not clear how
much more work remains to be done before the task is complete
(e.g. because the task is waiting for a remote host to respond), or
the progress is a number in the range zero to a maximum, giving the
fraction of work that has so far been completed.</p>
<p>There are two attributes that determine the current task
completion represented by the element.</p>
<p>The <dfn title="attr-progress-value"><code>value</code></dfn>
attribute specifies how much of the task has been completed, and the
<dfn title="attr-progress-max"><code>max</code></dfn> attribute
specifies how much work the task requires in total. The units are
arbitrary and not specified.</p>
<p>Instead of using the attributes, authors are recommended to
include the current value and the maximum value inline as text
inside the element.</p>
<div class="example">
<p>Here is a snippet of a Web application that shows the progress
of some automated task:</p>
<pre><section>
<h2>Task Progress</h2>
<p>Progress: <progress><span id="p">0</span>%</progress></p>
<script>
var progressBar = document.getElementById('p');
function updateProgress(newValue) {
progressBar.textContent = newValue;
}
</script>
</section></pre>
<p>(The <code>updateProgress()</code> method in this example would
be called by some other code on the page to update the actual
progress bar as the task progressed.)</p>
</div>
<p><span class="impl"><strong>Author requirements</strong>:</span>
The <code>progress</code> element must match one of the following
conditions.</p>
<ul>
<li>Neither the <code title="attr-progress-value">value</code>
attribute nor the <code title="attr-progress-max">max</code>
attribute is specified, and the element's contents
contain no numbers.</li>
<li>Neither the <code title="attr-progress-value">value</code>
attribute nor the <code title="attr-progress-max">max</code>
attribute is specified, and the element's contents contain one
number, optionally followed by a <span title="valid denominator
punctuation character">denominator punctuation
character</span>.</li>
<li>Neither the <code title="attr-progress-value">value</code>
attribute nor the <code title="attr-progress-max">max</code>
attribute is specified, and the element's contents contain two
numbers, neither followed by a <span title="valid denominator
punctuation character">denominator punctuation
character</span>.</li>
<li>The <code title="attr-progress-value">value</code> attribute is
not specified but the <code title="attr-progress-max">max</code>
attribute is specified, and the element's contents
contain one number that is not followed by a <span title="valid
denominator punctuation character">denominator punctuation
character</span>.</li>
<li>The <code title="attr-progress-value">value</code> attribute is
specified but the <code title="attr-progress-max">max</code>
attribute is not specified, and the element's contents contain no
numbers.</li>
<li>The <code title="attr-progress-value">value</code> attribute
and the <code title="attr-progress-max">max</code> attribute are
both specified. (The contents of the element are ignored.)</li>
</ul>
<!-- next three paragraphs are also in the <meter> section -->
<p>For the purposes of these requirements, a number is a sequence of
characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE
(9), optionally including a single U+002E FULL STOP character (.) in
some position after the first digit and before the last digit,
interpreted as a base ten number. Numbers must be separated from
other numbers by at least one character that isn't any of the
aforementioned. In addition, if the element is required to contain
numbers, then the contents of the element must not contain any
U+002E FULL STOP characters (.) that aren't part of numbers.</p>
<p>A number if said to be followed by a <span title="valid
denominator punctuation character">denominator punctuation
character</span> if it is followed by zero or more
<span>White_Space</span> characters and a <span>valid denominator
punctuation character</span>.</p>
<p>The contents of the element consist of the concatenation of
the <span title="text node">text nodes</span> of all the descendants
of the element, in <span>tree order</span>.</p>
<!-- previous three paragraphs are also in the <meter> section -->
<p>The <code title="attr-progress-value">value</code> and <code
title="attr-progress-max">max</code> attributes, when present, must
have values that are <span title="valid floating point number">valid
floating point numbers</span>. The <code
title="attr-progress-value">value</code> attribute, if present, must
have a value equal to or greater than zero, and less than or equal
to the value of the <code title="attr-progress-max">max</code>
attribute, if present, or 1.0, otherwise. If the <code
title="attr-progress-value">value</code> attribute is not present,
but the element's contents contain a number, then the value of the
first number in the element's contents must be less than or equal to
the value of the second number in the element's contents, if any, or
the <span title="values associated with denominator punctuation
characters">value associated with the denominator punctuation
character</span> that follows the first number in the element's
contents, if any, or 1.0, otherwise. The <code
title="attr-progress-max">max</code> attribute, if present, must
have a value greater than zero.</p>
<p class="note">The <code>progress</code> element is the wrong
element to use for something that is just a gauge, as opposed to
task progress. For instance, indicating disk space usage using
<code>progress</code> would be inappropriate. Instead, the
<code>meter</code> element is available for such use cases.</p>
<div class="impl">
<p><strong>User agent requirements</strong>: User agents must parse
the <code title="attr-progress-max">max</code> and <code
title="attr-progress-value">value</code> attributes' values
according to the <span>rules for parsing floating point number
values</span>.</p>
<p>If the <code title="attr-progress-value">value</code> attribute
is omitted, then user agents must also parse the
<code>textContent</code> of the <code>progress</code> element in
question using the <span>steps for finding one or two numbers of a
ratio in a string</span>. These steps will return nothing, one
number, one number with a <span title="valid denominator punctuation
character">denominator punctuation character</span>, or two
numbers.</p>
<p>Using the results of this processing, user agents must determine
whether the progress bar is an indeterminate progress bar, or
whether it is a determinate progress bar, and in the latter case,
what its current and maximum values are, all as follows:</p>
<ol>
<li>If the <code title="attr-progress-max">max</code> attribute is
omitted, and the <code title="attr-progress-value">value</code> is
omitted, and the result of parsing the <code>textContent</code> was
nothing, then the progress bar is an indeterminate progress
bar. Abort these steps.</li>
<li>Otherwise, it is a determinate progress bar.</li>
<li>If the <code title="attr-progress-max">max</code> attribute is
included, then, if a value could be parsed out of it, then the
maximum value is that value.</li>
<li>Otherwise, if the <code title="attr-progress-max">max</code>
attribute is absent but the <code
title="attr-progress-value">value</code> attribute is present, or,
if the <code title="attr-progress-max">max</code> attribute is
present but no value could be parsed from it, then the maximum is
1.</li>
<li>Otherwise, if neither attribute is included, then, if the
<code>textContent</code> contained one number with an associated
<span title="valid denominator punctuation character">denominator
punctuation character</span>, then the maximum value is the <span
title="values associated with denominator punctuation
characters">value associated with that denominator punctuation
character</span>; otherwise, if the <code>textContent</code>
contained two numbers, the maximum value is the higher of the two
values; otherwise, the maximum value is 1.</li>
<li>If the <code title="attr-progress-value">value</code> attribute
is present on the element and a value could be parsed out of it,
that value is the current value of the progress bar. Otherwise, if
the attribute is present but no value could be parsed from it, the
current value is zero.</li>
<li>Otherwise if the <code title="attr-progress-value">value</code>
attribute is absent and the <code
title="attr-progress-max">max</code> attribute is present, then, if
the <code>textContent</code> was parsed and found to contain just
one number, with no associated <span title="valid denominator
punctuation character">denominator punctuation character</span>,
then the current value is that number. Otherwise, if the <code
title="attr-progress-value">value</code> attribute is absent and
the <code title="attr-progress-max">max</code> attribute is present
then the current value is zero.</li>
<li>Otherwise, if neither attribute is present, then the current
value is the lower of the one or two numbers that were found in the
<code>textContent</code> of the element.</li>
<li>If the maximum value is less than or equal to zero, then it is
reset to 1.</li>
<li>If the current value is less than zero, then it is reset to
zero.</li>
<li>Finally, if the current value is greater than the maximum
value, then the current value is reset to the maximum value.</li>
</ol>
<p><strong>UA requirements for showing the progress bar</strong>:
When representing a <code>progress</code> element to the user, the
UA should indicate whether it is a determinate or indeterminate
progress bar, and in the former case, should indicate the relative
position of the current value relative to the maximum value.</p>
<p>The <dfn title="dom-progress-max"><code>max</code></dfn> and <dfn
title="dom-progress-value"><code>value</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name. When the relevant content attributes are absent, the IDL
attributes must return zero. The value parsed from the
<code>textContent</code> never affects the DOM values.</p>
</div>
<dl class="domintro">
<dt><var title="">progress</var> . <code title="dom-progress-position">position</code></dt>
<dd>
<p>For a determinate progress bar (one with known current and
maximum values), returns the result of dividing the current value
by the maximum value.</p>
<p>For an indeterminate progress bar, returns −1.</p>
</dl>
<div class="impl">
<p>If the progress bar is an indeterminate progress bar, then the
<dfn title="dom-progress-position"><code>position</code></dfn> IDL
attribute must return −1. Otherwise, it must return the result of
dividing the current value by the maximum value.</p>
</div>
<h4>The <dfn><code>meter</code></dfn> element</h4>
<!-- Keep this after <progress> and NOT close to <time> -->
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>, but there must be no <code>meter</code> element descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-meter-value">value</code></dd>
<dd><code title="attr-meter-min">min</code></dd>
<dd><code title="attr-meter-low">low</code></dd>
<dd><code title="attr-meter-high">high</code></dd>
<dd><code title="attr-meter-max">max</code></dd>
<dd><code title="attr-meter-optimum">optimum</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLMeterElement</dfn> : <span>HTMLElement</span> {
attribute float <span title="dom-meter-value">value</span>;
attribute float <span title="dom-meter-min">min</span>;
attribute float <span title="dom-meter-max">max</span>;
attribute float <span title="dom-meter-low">low</span>;
attribute float <span title="dom-meter-high">high</span>;
attribute float <span title="dom-meter-optimum">optimum</span>;
};</pre>
</dd>
</dl>
<p>The <code>meter</code> element <span>represents</span> a scalar
measurement within a known range, or a fractional value; for example
disk usage, the relevance of a query result, or the fraction of a
voting population to have selected a particular candidate.</p>
<p>This is also known as a gauge.</p>
<p class="note">The <code>meter</code> element should not be used to
indicate progress (as in a progress bar). For that role, HTML
provides a separate <code>progress</code> element.</p>
<p class="note">The <code>meter</code> element also does not
represent a scalar value of arbitrary range — for example, it
would be wrong to use this to report a weight, or height, unless
there is a known maximum value.</p>
<p>There are six attributes that determine the semantics of the
gauge represented by the element.</p>
<p>The <dfn title="attr-meter-min"><code>min</code></dfn> attribute
specifies the lower bound of the range, and the <dfn
title="attr-meter-max"><code>max</code></dfn> attribute specifies
the upper bound. The <dfn
title="attr-meter-value"><code>value</code></dfn> attribute
specifies the value to have the gauge indicate as the "measured"
value.</p>
<p>The other three attributes can be used to segment the gauge's
range into "low", "medium", and "high" parts, and to indicate which
part of the gauge is the "optimum" part. The <dfn
title="attr-meter-low"><code>low</code></dfn> attribute specifies
the range that is considered to be the "low" part, and the <dfn
title="attr-meter-high"><code>high</code></dfn> attribute specifies
the range that is considered to be the "high" part. The <dfn
title="attr-meter-optimum"><code>optimum</code></dfn> attribute
gives the position that is "optimum"; if that is higher than the
"high" value then this indicates that the higher the value, the
better; if it's lower than the "low" mark then it indicates that
lower values are better, and naturally if it is in between then it
indicates that neither high nor low values are good.</p>
<p><strong class="impl">Authoring requirements</strong>: The
recommended way of giving the value is to include it as contents of
the element, either as two numbers (the higher number represents the
maximum, the other number the current value, and the minimum is
assumed to be zero), or as a percentage or similar (using one of the
characters such as "%"), or as a fraction. However, it is also
possible to use the attributes to specify these values.</p>
<p>One of the following conditions, along with all the requirements
that are listed with that condition, must be met:</p>
<dl>
<dt>There are exactly two numbers in the contents of the element,
and the <code title="attr-meter-value">value</code>, <code
title="attr-meter-min">min</code>, and <code
title="attr-meter-max">max</code> attributes are all omitted</dt>
<dd>
<p>If specified, the <code title="attr-meter-low">low</code>,
<code title="attr-meter-high">high</code>, and <code
title="attr-meter-optimum">optimum</code> attributes must have
values greater than or equal to zero and less than or equal to the
bigger of the two numbers in the contents of the element.</p>
<p>If both the <code title="attr-meter-low">low</code> and <code
title="attr-meter-high">high</code> attributes are specified, then
the <code title="attr-meter-low">low</code> attribute's value must
be less than or equal to the value of the <code
title="attr-meter-high">high</code> attribute.</p>
<p>The numbers in the contents of the element must not be followed
by a <span title="valid denominator punctuation
character">denominator punctuation character</span>.</p>
</dd>
<dt>There is exactly one number followed by a <span title="valid
denominator punctuation character">denominator punctuation
character</span> in the contents of the element, and the <code
title="attr-meter-value">value</code>, <code
title="attr-meter-min">min</code>, and <code
title="attr-meter-max">max</code> attributes are all omitted</dt>
<dd>
<p>If specified, the <code title="attr-meter-low">low</code>,
<code title="attr-meter-high">high</code>, and <code
title="attr-meter-optimum">optimum</code> attributes must have
values greater than or equal to zero and less than or equal to the
<span title="values associated with denominator punctuation
characters">value associated with the denominator punctuation
character</span>.</p>
<p>If both the <code title="attr-meter-low">low</code> and <code
title="attr-meter-high">high</code> attributes are specified, then
the <code title="attr-meter-low">low</code> attribute's value must
be less than or equal to the value of the <code
title="attr-meter-high">high</code> attribute.</p>
<p>There must not be more than one number in the contents of the
element.</p>
</dd>
<dt>There is exactly one number in the contents of the element, and
the <code title="attr-meter-value">value</code> attribute is
omitted</dt>
<dt>There are no numbers in the contents of the element, and the
<code title="attr-meter-value">value</code> attribute is
specified</dt>
<dd>
<p>If the <code title="attr-meter-min">min</code> attribute
attribute is specified, then the <var title="">minimum</var> is
that attribute's value; otherwise, it is 0.</p>
<p>If the <code title="attr-meter-max">max</code> attribute
attribute is specified, then the <var title="">maximum</var> is
that attribute's value; otherwise, it is 1.</p>
<p>If the <code title="attr-meter-value">value</code> attribute is
specified, then the <var title="">value</var> is that attribute's
number; otherwise, there is exactly one number in the contents of
the element, and the <var title="">value</var> is that number.</p>
<p>The following inequalities must hold, as applicable:</p>
<ul class="brief">
<li><var title="">minimum</var> ≤ <var title="">value</var> ≤ <var title="">maximum</var></li>
<li><var title="">minimum</var> ≤ <code title="attr-meter-low">low</code> ≤ <var title="">maximum</var> (if <code title="attr-meter-low">low</code> is specified)</li>
<li><var title="">minimum</var> ≤ <code title="attr-meter-high">high</code> ≤ <var title="">maximum</var> (if <code title="attr-meter-high">high</code> is specified)</li>
<li><var title="">minimum</var> ≤ <code title="attr-meter-optimum">optimum</code> ≤ <var title="">maximum</var> (if <code title="attr-meter-optimum">optimum</code> is specified)</li>
</ul>
<p>If both the <code title="attr-meter-low">low</code> and <code
title="attr-meter-high">high</code> attributes are specified, then
the <code title="attr-meter-low">low</code> attribute's value must
be less than or equal to the value of the <code
title="attr-meter-high">high</code> attribute.</p>
<p>If the <code title="attr-meter-value">value</code> attribute is
not specified, the number in the contents of the element must not
be followed by a <span title="valid denominator punctuation
character">denominator punctuation character</span>. (Otherwise,
there is no restriction on what numbers can be in the contents of
the element.)</p>
</dd>
</dl>
<!-- next three paragraphs are also in the <progress> section -->
<p>For the purposes of these requirements, a number is a sequence of
characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE
(9), optionally including a single U+002E FULL STOP character (.) in
some position after the first digit and before the last digit,
interpreted as a base ten number. Numbers must be separated from
other numbers by at least one character that isn't any of the
aforementioned. In addition, if the element is required to contain
numbers, then the contents of the element must not contain any
U+002E FULL STOP characters (.) that aren't part of numbers.</p>
<p>A number if said to be followed by a <span title="valid
denominator punctuation character">denominator punctuation
character</span> if it is followed by zero or more
<span>White_Space</span> characters and a <span>valid denominator
punctuation character</span>.</p>
<p>The contents of the element consist of the concatenation of
the <span title="text node">text nodes</span> of all the descendants
of the element, in <span>tree order</span>.</p>
<!-- previous three paragraphs are also in the <progress> section -->
<p>The <code title="attr-meter-value">value</code>, <code
title="attr-meter-min">min</code>, <code
title="attr-meter-low">low</code>, <code
title="attr-meter-high">high</code>, <code
title="attr-meter-max">max</code>, and <code
title="attr-meter-optimum">optimum</code> attributes, when present,
must have values that are <span title="valid floating point
number">valid floating point numbers</span>.</p>
<p class="note">If no minimum or maximum is specified, then the
range is assumed to be 0..1, and the value thus has to be within
that range.</p>
<div class="example">
<p>The following examples all represent a measurement of three
quarters (of the maximum of whatever is being measured):</p>
<pre><meter>75%</meter>
<meter>750‰</meter>
<meter>3/4</meter>
<meter>6 blocks used (out of 8 total)</meter>
<meter>max: 100; current: 75</meter>
<meter><object data="graph75.png">0.75</object></meter> <!-- using <span class="bad"><img alt="0.75" ...></span> wouldn't work; the alt would be ignored -->
<meter min="0" max="100" value="75"></meter></pre>
<p>The following example is incorrect use of the element, because
it doesn't give a range (and since the default maximum is 1, both
of the gauges would end up looking maxed out):</p>
<pre class="bad"><p>The grapefruit pie had a radius of <meter>12cm</meter>
and a height of <meter>2cm</meter>.</p> <!-- <strong>BAD!</strong> --></pre>
<p>Instead, one would either not include the meter element, or use
the meter element with a defined range to give the dimensions in
context compared to other pies:</p>
<pre><p>The grapefruit pie had a radius of 12cm and a height of
2cm.</p>
<dl>
<dt>Radius: <dd> <meter min=0 max=20 value=12>12cm</meter>
<dt>Height: <dd> <meter min=0 max=10 value=2>2cm</meter>
</dl></pre>
</div>
<p>There is no explicit way to specify units in the
<code>meter</code> element, but the units may be specified in the
<code title="attr-title">title</code> attribute in free-form text.</p>
<div class="example">
<p>The example above could be extended to mention the units:</p>
<pre><dl>
<dt>Radius: <dd> <meter min=0 max=20 value=12 title="centimeters">12cm</meter>
<dt>Height: <dd> <meter min=0 max=10 value=2 title="centimeters">2cm</meter>
</dl></pre>
</div>
<div class="impl">
<p><strong>User agent requirements</strong>: User agents must parse
the <code title="attr-meter-min">min</code>, <code
title="attr-meter-max">max</code>, <code
title="attr-meter-value">value</code>, <code
title="attr-meter-low">low</code>, <code
title="attr-meter-high">high</code>, and <code
title="attr-meter-optimum">optimum</code> attributes using the
<span>rules for parsing floating point number values</span>.</p>
<p>If the <code title="attr-meter-value">value</code> attribute has
been omitted, the user agent must also process the
<code>textContent</code> of the element according to the <span>steps
for finding one or two numbers of a ratio in a string</span>. These
steps will return nothing, one number, one number with a <span
title="valid denominator punctuation character">denominator
punctuation character</span>, or two numbers.</p>
<p>User agents must then use all these numbers to obtain values for
six points on the gauge, as follows. (The order in which these are
evaluated is important, as some of the values refer to earlier
ones.)</p>
<dl>
<dt>The minimum value</dt>
<dd>
<p>If the <code title="attr-meter-min">min</code> attribute is
specified and a value could be parsed out of it, then the minimum
value is that value. Otherwise, the minimum value is zero.</p>
</dd>
<dt>The maximum value</dt>
<dd>
<p>If the <code title="attr-meter-max">max</code> attribute is
specified and a value could be parsed out of it, the maximum
value is that value.</p>
<p>Otherwise, if the <code title="attr-meter-max">max</code>
attribute is specified but no value could be parsed out of it, or
if it was not specified, but either or both of the <code
title="attr-meter-min">min</code> or <code
title="attr-meter-value">value</code> attributes <em>were</em>
specified, then the maximum value is 1.</p>
<p>Otherwise, none of the <code title="attr-meter-max">max</code>,
<code title="attr-meter-min">min</code>, and <code
title="attr-meter-value">value</code> attributes were
specified. If the result of processing the
<code>textContent</code> of the element was either nothing or just
one number with no <span title="valid denominator punctuation
character">denominator punctuation character</span>, then the
maximum value is 1; if the result was one number but it had an
associated <span title="valid denominator punctuation
character">denominator punctuation character</span>, then the
maximum value is the <span title="values associated with
denominator punctuation characters">value associated with that
denominator punctuation character</span>; and finally, if there
were two numbers parsed out of the <code>textContent</code>, then
the maximum is the higher of those two numbers.</p>
<p>If the above machinations result in a maximum value less than
the minimum value, then the maximum value is actually the same as
the minimum value.</p>
</dd>
<dt>The actual value</dt>
<dd>
<p>If the <code title="attr-meter-value">value</code> attribute is
specified and a value could be parsed out of it, then that value
is the actual value.</p>
<p>If the <code title="attr-meter-value">value</code> attribute is
not specified but the <code title="attr-meter-max">max</code>
attribute <em>is</em> specified and the result of processing the
<code>textContent</code> of the element was one number with no
associated <span title="valid denominator punctuation
character">denominator punctuation character</span>, then that
number is the actual value.</p>
<p>If neither of the <code title="attr-meter-value">value</code>
and <code title="attr-meter-max">max</code> attributes are
specified, then, if the result of processing the
<code>textContent</code> of the element was one number (with or
without an associated <span title="valid denominator punctuation
character">denominator punctuation character</span>), then that is
the actual value, and if the result of processing the
<code>textContent</code> of the element was two numbers, then the
actual value is the lower of the two numbers found.</p>
<p>Otherwise, if none of the above apply, the actual value is
zero.</p>
<p>If the above procedure results in an actual value less than
the minimum value, then the actual value is actually the same as
the minimum value.</p>
<p>If, on the other hand, the result is an actual value greater
than the maximum value, then the actual value is the maximum
value.</p>
</dd>
<dt>The low boundary</dt>
<dd>
<p>If the <code title="attr-meter-low">low</code> attribute is
specified and a value could be parsed out of it, then the low
boundary is that value. Otherwise, the low boundary is the same as
the minimum value.</p>
<p>If the low boundary is then less than the minimum value, then
the low boundary is actually the same as the minimum
value. Similarly, if the low boundary is greater than the maximum
value, then it is actually the maximum value instead.</p>
</dd>
<dt>The high boundary</dt>
<dd>
<p>If the <code title="attr-meter-high">high</code> attribute is
specified and a value could be parsed out of it, then the high
boundary is that value. Otherwise, the high boundary is the same
as the maximum value.</p>
<p>If the high boundary is then less than the low boundary, then
the high boundary is actually the same as the low
boundary. Similarly, if the high boundary is greater than the
maximum value, then it is actually the maximum value instead.</p>
</dd>
<dt>The optimum point</dt>
<dd>
<p>If the <code title="attr-meter-optimum">optimum</code>
attribute is specified and a value could be parsed out of it, then
the optimum point is that value. Otherwise, the optimum point is
the midpoint between the minimum value and the maximum value.</p>
<p>If the optimum point is then less than the minimum value, then
the optimum point is actually the same as the minimum
value. Similarly, if the optimum point is greater than the maximum
value, then it is actually the maximum value instead.</p>
</dd>
</dl>
<p>All of which will result in the following inequalities all being
true:</p>
<ul class="brief">
<li>minimum value ≤ actual value ≤ maximum value</li>
<li>minimum value ≤ low boundary ≤ high boundary ≤ maximum value</li>
<li>minimum value ≤ optimum point ≤ maximum value</li>
</ul>
<!-- next two paragraphs are duplicated in the <datagrid> section [v2DATAGRID] -->
<p><strong>UA requirements for regions of the gauge</strong>: If the
optimum point is equal to the low boundary or the high boundary, or
anywhere in between them, then the region between the low and high
boundaries of the gauge must be treated as the optimum region, and
the low and high parts, if any, must be treated as
suboptimal. Otherwise, if the optimum point is less than the low
boundary, then the region between the minimum value and the low
boundary must be treated as the optimum region, the region between
the low boundary and the high boundary must be treated as a
suboptimal region, and the region between the high boundary and the
maximum value must be treated as an even less good region. Finally,
if the optimum point is higher than the high boundary, then the
situation is reversed; the region between the high boundary and the
maximum value must be treated as the optimum region, the region
between the high boundary and the low boundary must be treated as a
suboptimal region, and the remaining region between the low boundary
and the minimum value must be treated as an even less good
region.</p>
<p><strong>UA requirements for showing the gauge</strong>: When
representing a <code>meter</code> element to the user, the UA should
indicate the relative position of the actual value to the minimum
and maximum values, and the relationship between the actual value
and the three regions of the gauge.</p>
</div>
<div class="example">
<p>The following markup:</p>
<pre><h3>Suggested groups</h3>
<menu type="toolbar">
<a href="?cmd=hsg" onclick="hideSuggestedGroups()">Hide suggested groups</a>
</menu>
<ul>
<li>
<p><a href="/group/comp.infosystems.www.authoring.stylesheets/view">comp.infosystems.www.authoring.stylesheets</a> -
<a href="/group/comp.infosystems.www.authoring.stylesheets/subscribe">join</a></p>
<p>Group description: <strong>Layout/presentation on the WWW.</strong></p>
<p><strong><meter value="0.5">Moderate activity,</meter></strong> Usenet, 618 subscribers</p>
</li>
<li>
<p><a href="/group/netscape.public.mozilla.xpinstall/view">netscape.public.mozilla.xpinstall</a> -
<a href="/group/netscape.public.mozilla.xpinstall/subscribe">join</a></p>
<p>Group description: <strong>Mozilla XPInstall discussion.</strong></p>
<p><strong><meter value="0.25">Low activity,</meter></strong> Usenet, 22 subscribers</p>
</li>
<li>
<p><a href="/group/mozilla.dev.general/view">mozilla.dev.general</a> -
<a href="/group/mozilla.dev.general/subscribe">join</a></p>
<p><strong><meter value="0.25">Low activity,</meter></strong> Usenet, 66 subscribers</p>
</li>
</ul></pre>
<p>Might be rendered as follows:</p>
<p><img src="images/sample-meter.png" alt="With the <meter> elements rendered as inline green bars of varying lengths."></p>
</div>
<p>User agents <span class="impl">may</span> combine the value of
the <code title="attr-title">title</code> attribute and the other
attributes to provide context-sensitive help or inline text
detailing the actual values.</p>
<div class="example">
<p>For example, the following snippet:</p>
<pre><meter min=0 max=60 value=23.2 title=seconds></meter></pre>
<p>...might cause the user agent to display a gauge with a tooltip
saying "Value: 23.2 out of 60." on one line and "seconds" on a
second line.</p>
</div>
<div class="impl">
<p>The <dfn title="dom-meter-min"><code>min</code></dfn>, <dfn
title="dom-meter-max"><code>max</code></dfn>, <dfn
title="dom-meter-value"><code>value</code></dfn>, <dfn
title="dom-meter-low"><code>low</code></dfn>, <dfn
title="dom-meter-high"><code>high</code></dfn>, and <dfn
title="dom-meter-optimum"><code>optimum</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name. When the relevant content attributes are absent, the IDL
attributes must return zero. The value parsed from the
<code>textContent</code> never affects the DOM values.</p>
</div>
<div class="example">
<p>The following example shows how a gauge could fall back to
localized or pretty-printed text. The attributes have to be used in
this case, since the localized or pretty-printed numbers might not
match the simple expected syntax.</p>
<pre><p>Disk usage: <meter min=0 value=170261928 max=233257824>170 261 928 bytes used
out of 233 257 824 bytes available</meter></p></pre>
</div>
<h4>The <dfn><code>ruby</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>One or more groups of: <span>phrasing content</span> followed either by a single <code>rt</code> element, or an <code>rp</code> element, an <code>rt</code> element, and another <code>rp</code> element.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>ruby</code> element allows one or more spans of
phrasing content to be marked with ruby annotations. Ruby
annotations are short runs of text presented alongside base text,
primarily used in East Asian typography as a guide for
pronunciation or to include other annotations. In Japanese, this
form of typography is also known as <i>furigana</i>.</p>
<p>A <code>ruby</code> element <span>represents</span> the spans of
phrasing content it contains, ignoring all the child <code>rt</code>
and <code>rp</code> elements and their descendants. Those spans of
phrasing content have associated annotations created using the
<code>rt</code> element.</p>
<div class="example">
<!-- this is the hiragana for the word "kanji" ("chinese character") in japanese -->
<!-- in japanese, ruby-like typography is called "furigana" -->
<p>In this example, each ideograph in the Japanese text <span
title="" lang="ja">漢字</span> is annotated with its
reading in hiragana.</p>
<pre lang="ja">...
<ruby>
漢 <rt> かん </rt>
字 <rt> じ　 </rt>
</ruby>
...</pre>
<p>This might be rendered as:</p>
<p><img src="images/sample-ruby-ja.png"
alt="The two main ideographs, each with its annotation in hiragana rendered in a smaller font above it."></p>
</div>
<div class="example">
<!-- this is the bopomofo for the word "hanzi" ("chinese character") in traditional chinese, as used in taiwan -->
<p>In this example, each ideograph in the traditional Chinese text
<span title="" lang="zh-TW">漢字</span> is annotated
with its bopomofo reading.</p>
<pre lang="zh-TW"><ruby>
漢 <rt> ㄏㄢˋ </rt>
字 <rt> ㄗˋ　 </rt>
</ruby></pre>
<p>This might be rendered as:</p>
<p><img src="images/sample-ruby-bopomofo.png"
alt="The two main ideographs, each with its bopomofo annotation rendered in a smaller font next to it."></p>
</div>
<div class="example">
<!-- this is the pinyin for the word "hanzi" ("chinese character") in simplified chinese, as used in mainland china -->
<p>In this example, each ideograph in the simplified Chinese text
<span title="" lang="zh-CN">汉字</span> is annotated
with its pinyin reading.</p>
<pre lang="zh-CN">...
<ruby>
汉 <rt> hàn </rt>
字 <rt> zì </rt>
</ruby>
...</pre>
<p>This might be rendered as:</p>
<p><img src="images/sample-ruby-pinyin.png"
alt="The two main ideographs, each with its pinyin annotation rendered in a smaller font above it."></p>
</div>
<!-- Note: Examples are 32px/16px Stone Sans Sem ITC TT -->
<h4>The <dfn><code>rt</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>ruby</code> element.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>rt</code> element marks the ruby text component of a
ruby annotation.</p>
<p>An <code>rt</code> element <span class="impl">that is a child of
a <code>ruby</code> element</span> <span>represents</span> an
annotation (given by its children) for the zero or more nodes of
phrasing content that immediately precedes it in the
<code>ruby</code> element, ignoring <code>rp</code> elements.</p>
<div class="impl">
<p>An <code>rt</code> element that is not a child of a
<code>ruby</code> element represents the same thing as its
children.</p>
</div>
<h4>The <dfn><code>rp</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>ruby</code> element, either immediately before or immediately after an <code>rt</code> element.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<!--
<dd>If the <code>rp</code> element is immediately after an <code>rt</code> element that is immediately preceded by another <code>rp</code> element: a single character from Unicode character class Pe.</dd>
<dd>Otherwise: a single character from Unicode character class Ps.</dd>
-->
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>rp</code> element can be used to provide parentheses
around a ruby text component of a ruby annotation, to be shown by
user agents that don't support ruby annotations.</p>
<p>An <code>rp</code> element <span class="impl">that is a child of
a <code>ruby</code> element</span> <span>represents</span>
nothing<span class="impl"> and its contents must be
ignored</span>. <span class="impl">An <code>rp</code> element whose
parent element is not a <code>ruby</code> element
<span>represents</span> its children.</span></p>
<div class="example">
<p>The example above, in which each ideograph in the text <span
title="" lang="ja">漢字</span> is annotated with its
kanji reading, could be expanded to use <code>rp</code> so that in
legacy user agents the readings are in parentheses:</p>
<pre lang="ja">...
<ruby>
漢 <rp>(</rp><rt>かん</rt><rp>)</rp>
字 <rp>(</rp><rt>じ</rt><rp>)</rp>
</ruby>
...</pre>
<p>In conforming user agents the rendering would be as above, but
in user agents that do not support ruby, the rendering would
be:</p>
<pre lang="ja">... 漢 (かん) 字 (じ) ...</pre>
</div>
<h4>The <dfn><code>bdo</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd>Also, the <code title="attr-dir">dir</code> global attribute has special semantics on this element.</dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<p>The <code>bdo</code> element <span>represents</span> explicit
text directionality formatting control for its children. It allows
authors to override the Unicode bidi algorithm by explicitly
specifying a direction override. <a href="#refsBIDI">[BIDI]</a></p>
<p>Authors must specify the <code title="attr-dir">dir</code>
attribute on this element, with the value <code>ltr</code> to
specify a left-to-right override and with the value <code>rtl</code>
to specify a right-to-left override.</p>
<div class="impl">
<p>If the element has the <code title="attr-dir">dir</code>
attribute set to the exact value <code>ltr</code>, then for the
purposes of the bidi algorithm, the user agent must act as if there
was a U+202D LEFT-TO-RIGHT OVERRIDE character at the start of the
element, and a U+202C POP DIRECTIONAL FORMATTING at the end of the
element.</p>
<p>If the element has the <code title="attr-dir">dir</code>
attribute set to the exact value <code>rtl</code>, then for the
purposes of the bidi algorithm, the user agent must act as if there
was a U+202E RIGHT-TO-LEFT OVERRIDE character at the start of the
element, and a U+202C POP DIRECTIONAL FORMATTING at the end of the
element.</p>
<p>The requirements on handling the <code>bdo</code> element for the
bidi algorithm may be implemented indirectly through the style
layer. For example, an HTML+CSS user agent should implement these
requirements by implementing the CSS 'unicode-bidi' property. <a
href="#refsCSS">[CSS]</a></p>
</div>
<h4>The <dfn><code>span</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLSpanElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>span</code> element doesn't mean anything on its own,
but can be useful when used together with other attributes,
e.g. <code title="attr-class">class</code>, <code
title="attr-lang">lang</code>, or <code
title="attr-dir">dir</code>. It <span>represents</span> its
children.</p>
<div class="example">
<p>In this example, a code fragment is marked up using
<code>span</code> elements and <code
title="attr-class">class</code> attributes so that its keywords and
identifiers can be color-coded from CSS:</p>
<!-- extract from http://www.cs.cmu.edu/~dst/DeCSS/Gallery/vlc-dvd_css-c.txt -->
<pre><pre><code class="lang-c"><span class="keyword">for</span> (<span class="ident">j</span> = 0; <span class="ident">j</span> &lt; 256; <span class="ident">j</span>++) {
<span class="ident">i_t3</span> = (<span class="ident">i_t3</span> & 0x1ffff) | (<span class="ident">j</span> &lt;&lt; 17);
<span class="ident">i_t6</span> = (((((((<span class="ident">i_t3</span> >> 3) ^ <span class="ident">i_t3</span>) >> 1) ^ <span class="ident">i_t3</span>) >> 8) ^ <span class="ident">i_t3</span>) >> 5) & 0xff;
<span class="keyword">if</span> (<span class="ident">i_t6</span> == <span class="ident">i_t1</span>)
<span class="keyword">break</span>;
}</code></pre></pre>
</div>
<h4>Usage summary</h4>
<p><i>This section is non-normative.</i></p>
<table>
<thead>
<tr>
<th>Element
<th>Purpose
<th>Example
<tbody>
<tr>
<td><code>a</code>
<td>Hyperlinks
<td><pre class="example">Visit my <strong><a href="drinks.html">drinks</a></strong> page.</pre>
<tr>
<td><code>em</code>
<td>Stress emphasis
<td><pre class="example">I must say I <strong><em>adore</em></strong> lemonade.</pre>
<tr>
<td><code>strong</code>
<td>Importance
<td><pre class="example">This tea is <strong><strong>very hot</strong></strong>.</pre>
<tr>
<td><code>small</code>
<td>Side comments
<td><pre class="example">These grapes are made into wine. <strong><small>Alcohol is addictive.</small></strong></pre>
<tr>
<td><code>cite</code>
<td>Titles of works
<td><pre class="example">The case <strong><cite>Hugo v. Danielle</cite></strong> is relevant here.</pre>
<tr>
<td><code>q</code>
<td>Quotations
<td><pre class="example">The judge said <strong><q>You can drink water from the fish tank</q></strong> but advised against it.</pre>
<tr>
<td><code>dfn</code>
<td>Defining instance
<td><pre class="example">The term <strong><dfn>organic food</dfn></strong> refers to food produced without synthetic chemicals.</pre>
<tr>
<td><code>abbr</code>
<td>Abbreviations
<td><pre class="example">Organic food in Ireland is certified by the <strong><abbr title="Irish Organic Farmers and Growers Association">IOFGA</abbr></strong>.</pre>
<tr>
<td><code>time</code>
<td>Date and/or time
<td><pre class="example">Published <strong><time>2009-10-21</time></strong>.</pre>
<tr>
<td><code>code</code>
<td>Computer code
<td><pre class="example">The <strong><code>fruitdb</code></strong> program can be used for tracking fruit production.</pre>
<tr>
<td><code>var</code>
<td>Variables
<td><pre class="example">If there are <strong><var>n</var></strong> fruit in the bowl, at least <strong><var>n</var></strong>÷2 will be ripe.</pre>
<tr>
<td><code>samp</code>
<td>Computer output
<td><pre class="example">The computer said <strong><samp>Unknown error -3</samp></strong>.</pre>
<tr>
<td><code>kbd</code>
<td>User input
<td><pre class="example">Hit <strong><kbd>F1</kbd></strong> to continue.</pre>
<tr>
<td><code>sub</code>
<td>Subscripts
<td><pre class="example">Water is H<strong><sub>2</sub></strong>O.</pre>
<tr>
<td><code>sup</code>
<td>Superscripts
<td><pre class="example">The Hydrogen in heavy water is usually <strong><sup>2</sup></strong>H.</pre>
<tr>
<td><code>i</code>
<td>Alternative voice
<td><pre class="example">Lemonade consists primarily of <strong><i>Citrus limon</i></strong>.</pre>
<tr>
<td><code>b</code>
<td>Keywords
<td><pre class="example">Take a <strong><b>lemon</b></strong> and squeeze it with a <strong><b>juicer</b></strong>.</pre>
<tr>
<td><code>mark</code>
<td>Highlight
<td><pre class="example">Elderflower cordial, with one <strong><mark>part</mark></strong> cordial to ten <strong><mark>part</mark></strong>s water, stands a<strong><mark>part</mark></strong> from the rest.</pre>
<tr>
<td><code>progress</code>
<td>Progress bar
<td><pre class="example">Copying: <strong><progress>75%</progress></strong></pre>
<tr>
<td><code>meter</code>
<td>Gauge
<td><pre class="example">Disk space remaining: <strong><meter>75%<meter></strong></pre>
<tr>
<td><code>ruby</code>, <code>rt</code>, <code>rp</code>
<td>Ruby annotations
<td><pre class="example"><strong><ruby> OJ <rp>(<rt>Orange Juice<rp>)</ruby></strong></pre>
<tr>
<td><code>bdo</code>
<td>Text directionality formatting
<td><pre class="example">The proposal is to write English, but in reverse order. "Juice" would become "<strong><bdo dir=rtl>Juice</bdo></strong>"</pre>
<tr>
<td><code>span</code>
<td>Other
<td><pre class="example">In French we call it <strong><span lang="fr">sirop de sureau</span></strong>.</pre>
</table>
<h3>Edits</h3>
<p>The <code>ins</code> and <code>del</code> elements represent
edits to the document.</p>
<h4>The <dfn><code>ins</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd>When the element only contains <span>phrasing content</span>: <span>phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Transparent</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-mod-cite">cite</code></dd>
<dd><code title="attr-mod-datetime">datetime</code></dd>
<dt>DOM interface:</dt>
<dd>Uses the <code>HTMLModElement</code> interface.</dd>
</dl>
<p>The <code>ins</code> element <span>represents</span> an addition
to the document.</p>
<div class="example">
<p>The following represents the addition of a single paragraph:</p>
<pre><aside>
<ins>
<p> I like fruit. </p>
</ins>
</aside></pre>
<p>As does this, because everything in the <code>aside</code>
element here counts as <span>phrasing content</span> and therefore
there is just one <span>paragraph</span>:</p>
<pre><aside>
<ins>
Apples are <em>tasty</em>.
</ins>
<ins>
So are pears.
</ins>
</aside></pre>
</div>
<p><code>ins</code> elements should not cross <span
title="paragraph">implied paragraph</span> boundaries.</p>
<div class="example">
<p>The following example represents the addition of two paragraphs,
the second of which was inserted in two parts. The first
<code>ins</code> element in this example thus crosses a paragraph
boundary, which is considered poor form.</p>
<pre class="bad"><aside>
<!-- don't do this -->
<ins datetime="2005-03-16T00:00Z">
<p> I like fruit. </p>
Apples are <em>tasty</em>.
</ins>
<ins datetime="2007-12-19T00:00Z">
So are pears.
</ins>
</aside></pre>
<p>Here is a better way of marking this up. It uses more elements,
but none of the elements cross implied paragraph boundaries.</p>
<pre><aside>
<ins datetime="2005-03-16T00:00Z">
<p> I like fruit. </p>
</ins>
<ins datetime="2005-03-16T00:00Z">
Apples are <em>tasty</em>.
</ins>
<ins datetime="2007-12-19T00:00Z">
So are pears.
</ins>
</aside></pre>
<!-- Those dates aren't random. They're the start and end of
something. Can you guess what? -->
</div>
<h4>The <dfn><code>del</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd>When the element only contains <span>phrasing content</span>: <span>phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Transparent</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-mod-cite">cite</code></dd>
<dd><code title="attr-mod-datetime">datetime</code></dd>
<dt>DOM interface:</dt>
<dd>Uses the <code>HTMLModElement</code> interface.</dd>
</dl>
<p>The <code>del</code> element <span>represents</span> a removal
from the document.</p>
<p><code>del</code> elements should not cross <span
title="paragraph">implied paragraph</span> boundaries.</p>
<div class="example">
<p>The following shows a "to do" list where items that have been
done are crossed-off with the date and time of their
completion.</p>
<pre><h1>To Do</h1>
<ul>
<li>Empty the dishwasher</li>
<li><del datetime="2009-10-11T01:25-07:00">Watch Walter Lewin's lectures</del></li>
<li><del datetime="2009-10-10T23:38-07:00">Download more tracks</del></li>
<li>Buy a printer</li>
</ul></pre>
</div>
<h4>Attributes common to <code>ins</code> and <code>del</code> elements</h4>
<p>The <dfn title="attr-mod-cite"><code>cite</code></dfn> attribute
may be used to specify the address of a document that explains the
change. When that document is long, for instance the minutes of a
meeting, authors are encouraged to include a fragment identifier
pointing to the specific part of that document that discusses the
change.</p>
<p>If the <code title="attr-mod-cite">cite</code> attribute is
present, it must be a <span>valid URL</span> that explains the
change. <span class="impl">To obtain the corresponding citation
link, the value of the attribute must be <span title="resolve a
url">resolved</span> relative to the element. User agents should
allow users to follow such citation links.</span></p>
<p>The <dfn title="attr-mod-datetime"><code>datetime</code></dfn>
attribute may be used to specify the time and date of the change.</p>
<p>If present, the <code title="attr-mod-datetime">datetime</code>
attribute must be a <span>valid global date and time string</span>
value.</p>
<div class="impl">
<p>User agents must parse the <code
title="attr-mod-datetime">datetime</code> attribute according to the
<span>parse a global date and time string</span> algorithm. If that
doesn't return a time, then the modification has no associated
timestamp (the value is non-conforming; it is not a <span>valid
global date and time string</span>). Otherwise, the modification is
marked as having been made at the given datetime. User agents should
use the associated time-zone offset information to determine which
time zone to present the given datetime in.</p>
</div>
<p>The <code>ins</code> and <code>del</code> elements <span
class="impl">must</span> implement the <code>HTMLModElement</code>
interface:</p>
<pre class="idl">interface <dfn>HTMLModElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-mod-cite">cite</span>;
attribute DOMString <span title="dom-mod-datetime">dateTime</span>;
};</pre>
<div class="impl">
<p>The <dfn title="dom-mod-cite"><code>cite</code></dfn> IDL
attribute must <span>reflect</span> the element's <code
title="attr-mod-cite">cite</code> content attribute. The <dfn
title="dom-mod-datetime"><code>dateTime</code></dfn> IDL attribute
must <span>reflect</span> the element's <code
title="">datetime</code> content attribute.</p>
</div>
<h4>Edits and paragraphs</h4>
<p><i>This section is non-normative.</i></p>
<p>Since the <code>ins</code> and <code>del</code> elements do not
affect <span title="paragraph">paragraphing</span>, it is possible,
in some cases where paragraphs are <span
title="paragraph">implied</span> (without explicit <code>p</code>
elements), for an <code>ins</code> or <code>del</code> element to
span both an entire paragraph or other non-<span>phrasing
content</span> elements and part of another paragraph. For
example:</p>
<pre><section>
<ins>
<p>
This is a paragraph that was inserted.
</p>
This is another paragraph whose first sentence was inserted
at the same time as the paragraph above.
</ins>
This is a second sentence, which was there all along.
</section></pre>
<p>By only wrapping some paragraphs in <code>p</code> elements, one
can even get the end of one paragraph, a whole second paragraph,
and the start of a third paragraph to be covered by the same
<code>ins</code> or <code>del</code> element (though this is very
confusing, and not considered good practice):</p>
<pre class="bad"><section>
This is the first paragraph. <ins>This sentence was
inserted.
<p>This second paragraph was inserted.</p>
This sentence was inserted too.</ins> This is the
third paragraph in this example.
<!-- (don't do this) -->
</section></pre>
<p>However, due to the way <span title="paragraph">implied
paragraphs</span> are defined, it is not possible to mark up the
end of one paragraph and the start of the very next one using the
same <code>ins</code> or <code>del</code> element. You instead have
to use one (or two) <code>p</code> element(s) and two
<code>ins</code> or <code>del</code> elements, as for example:</p>
<pre><section>
<p>This is the first paragraph. <del>This sentence was
deleted.</del></p>
<p><del>This sentence was deleted too.</del> That
sentence needed a separate &lt;del&gt; element.</p>
</section></pre>
<p>Partly because of the confusion described above, authors are
strongly encouraged to always mark up all paragraphs with the
<code>p</code> element, instead of having <code>ins</code> or
<code>del</code> elements that cross <span title="paragraph">implied
paragraphs</span> boundaries.</p>
<h4>Edits and lists</h4>
<p><i>This section is non-normative.</i></p>
<p>The content models of the <code>ol</code> and <code>ul</code>
elements do not allow <code>ins</code> and <code>del</code> elements
as children. Lists always represent all their items, including items
that would otherwise have been marked as deleted.</p>
<p>To indicate that an item is inserted or deleted, an
<code>ins</code> or <code>del</code> element can be wrapped around
the contents of the <code>li</code> element. To indicate that an
item has been replaced by another, a single <code>li</code> element
can have one or more <code>del</code> elements followed by one or
more <code>ins</code> elements.</p>
<div class="example">
<p>In the following example, a list that started empty had items
added and removed from it over time. The bits in the example that
have been emphasized show the parts that are the "current" state of
the list. The list item numbers don't take into account the edits,
though.</p>
<pre><h1>Stop-ship bugs</h1>
<ol>
<li><ins datetime="2008-02-12T15:20Z"><em>Bug 225:
Rain detector doesn't work in snow</em></ins></li>
<li><del datetime="2008-03-01T20:22Z"><ins datetime="2008-02-14T12:02Z">Bug 228:
Water buffer overflows in April</ins></del></li>
<li><ins datetime="2008-02-16T13:50Z"><em>Bug 230:
Water heater doesn't use renewable fuels</em></ins></li>
<li><del datetime="2008-02-20T21:15Z"><ins datetime="2008-02-16T14:25Z">Bug 232:
Carbon dioxide emissions detected after startup</ins></del></li>
</ol></pre>
</div>
<div class="example">
<p>In the following example, a list that started with just fruit
was replaced by a list with just colors.</p>
<pre><h1>List of <del>fruits</del><ins>colors</ins></h1>
<ul>
<li><del>Lime</del><ins>Green</ins></li>
<li><del>Apple</del></li>
<li>Orange</li>
<li><del>Pear</del></li>
<li><ins>Teal</ins></li>
<li><del>Lemon</del><ins>Yellow</ins></li>
<li>Olive</li>
<li><ins>Purple</ins>
</ul></pre>
</div>
<h3>Embedded content</h3>
<h4>The <dfn><code>figure</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Sectioning root</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>In any order, one <code>dd</code> element, and optionally one <code>dt</code> element.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>Uses <code>HTMLElement</code>.</dd>
</dl>
<!-- v2: Add a <dc> or <credit> element for photo credits -->
<p>The <code>figure</code> element <span>represents</span> some
<span>flow content</span>, optionally with a caption, that is
self-contained and is typically referenced as a single unit from the
main flow of the document.</p>
<p>The element can thus be used to annotate illustrations, diagrams,
photos, code listings, etc, that are referred to from the main
content of the document, but that could, without affecting the flow
of the document, be moved away from that primary content, e.g. to
the side of the page, to dedicated pages, or to an appendix.</p>
<p>The <span class="impl">first</span> <code>dt</code> element child
of the element, if any, represents the caption of the
<code>figure</code> element's contents. If there is no child
<code>dt</code> element, then there is no caption.</p>
<p>The <span class="impl">first</span> <code>dd</code> element child
of the element<span class="impl">, if any,</span> represents the
element's contents. <span class="impl">If there is no child
<code>dd</code> element, then there are no contents.</span></p>
<div class="example">
<p>This example shows the <code>figure</code> element to mark up a
code listing.</p>
<pre><p>In <a href="#l4">listing 4</a> we see the primary core interface
API declaration.</p>
<figure id="l4">
<dt>Listing 4. The primary core interface API declaration.</dt>
<dd>
<pre><code>interface PrimaryCore {
boolean verifyDataLine();
void sendData(in sequence&lt;byte> data);
void initSelfDestruct();
}</code></pre>
</dd>
</figure>
<p>The API is designed to use UTF-8.</p></pre>
</div>
<div class="example">
<p>Here we see a <code>figure</code> element to mark up a
photo.</p>
<pre><figure>
<dd>
<img src="bubbles-work.jpeg"
alt="Bubbles, sitting in his office chair, works on his
latest project intently.">
</dd>
<dt>Bubbles at work</dt>
</figure></pre>
</div>
<div class="example">
<p>In this example, we see an image that is <em>not</em>
a figure, as well as an image and a video that are.</p>
<pre><h2>Malinko's comics</h2>
<p>This case centered on some sort of "intellectual property"
infringement related to a comic (see Exhibit A). The suit started
after a trailer ending with these words:
<blockquote>
<img src="promblem-packed-action.png" alt="ROUGH COPY! Promblem-Packed Action!">
</blockquote>
<p>...was aired. A lawyer, armed with a Bigger Notebook, launched a
preemptive strike using snowballs. A complete copy of the trailer is
included with Exhibit B.
<figure>
<dd><img src="ex-a.png" alt="Two squiggles on a dirty piece of paper.">
<dt>Exhibit A. The alleged <cite>rough copy</cite> comic.
</figure>
<figure>
<dd><video src="ex-b.mov"></video>
<dt>Exhibit B. The <cite>Rough Copy</cite> trailer.
</figure>
<p>The case was resolved out of court.</pre>
</div>
<div class="example">
<p>Here, a part of a poem is marked up using
<code>figure</code>.</p>
<pre><figure>
<dd>
<p>'Twas brillig, and the slithy toves<br>
Did gyre and gimble in the wabe;<br>
All mimsy were the borogoves,<br>
And the mome raths outgrabe.</p>
</dd>
<dt><cite>Jabberwocky</cite> (first verse). Lewis Carroll, 1832-98</dt>
</figure></pre>
</div>
<div class="example">
<p>In this example, which could be part of a much larger work
discussing a castle, the figure has three images in it.</p>
<pre><figure>
<dd>
<img src="castle1423.jpeg" title="Etching. Anonymous, ca. 1423."
alt="The castle has one tower, and a tall wall around it.">
<img src="castle1858.jpeg" title="Oil-based paint on canvas. Maria Towle, 1858."
alt="The castle now has two towers and two walls.">
<img src="castle1999.jpeg" title="Film photograph. Peter Jankle, 1999."
alt="The castle lies in ruins, the original tower all that remains in one piece.">
</dd>
<dt>The castle through the ages: 1423, 1858, and 1999 respectively.</dt>
</figure></pre>
</div>
<h4>The <dfn><code>img</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Embedded content</span>.</dd>
<dd>If the element has a <code title="attr-hyperlink-usemap">usemap</code> attribute: <span>Interactive content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>embedded content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-img-alt">alt</code></dd>
<dd><code title="attr-img-src">src</code></dd>
<dd><code title="attr-hyperlink-usemap">usemap</code></dd>
<dd><code title="attr-img-ismap">ismap</code></dd>
<dd><code title="attr-dim-width">width</code></dd>
<dd><code title="attr-dim-height">height</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">[NamedConstructor=<span title="dom-image">Image</span>(),
NamedConstructor=<span title="dom-image-w">Image</span>(in unsigned long width),
NamedConstructor=<span title="dom-image-wh">Image</span>(in unsigned long width, in unsigned long height)]
interface <dfn>HTMLImageElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-img-alt">alt</span>;
attribute DOMString <span title="dom-img-src">src</span>;
attribute DOMString <span title="dom-img-useMap">useMap</span>;
attribute boolean <span title="dom-img-isMap">isMap</span>;
attribute unsigned long <span title="dom-img-width">width</span>;
attribute unsigned long <span title="dom-img-height">height</span>;
readonly attribute unsigned long <span title="dom-img-naturalWidth">naturalWidth</span>;
readonly attribute unsigned long <span title="dom-img-naturalHeight">naturalHeight</span>;
readonly attribute boolean <span title="dom-img-complete">complete</span>;
};</pre>
</dd>
</dl>
<p>An <code>img</code> element represents an image.</p>
<!-- v2 ideas for <img>:
* Maps sites would like to know which images are already cached,
so that they can use images that are vaguely suitable while
they wait for the most appropriate image to download.
Almost like lowsrc="", except that many images might be
appropriate.
Slight hitch: their images are at a different origin, and we
don't want to allow arbitrary cross-origin inspection (privacy
leak risk).
* See note at rel=noreferrer.
-->
<p>The image given by the <dfn
title="attr-img-src"><code>src</code></dfn> attribute is the
embedded content, and the value of the <dfn
title="attr-img-alt"><code>alt</code></dfn> attribute is the
<code>img</code> element's <span>fallback content</span>.</p>
<p>The <code title="attr-img-src">src</code> attribute must be
present, and must contain a <span>valid URL</span> referencing a
non-interactive, optionally animated, image resource that is neither
paged nor scripted. If the <i>base URI of the element</i> is the
same as <span>the document's address</span>, then the <code
title="attr-img-src">src</code> attribute's value must not be the
empty string.</p>
<p class="note">Images can thus be static bitmaps (e.g. PNGs, GIFs,
JPEGs), single-page vector documents (single-page PDFs, XML files
with an SVG root element), animated bitmaps (APNGs, animated GIFs),
animated vector graphics (XML files with an SVG root element that
use declarative SMIL animation), and so forth. However, this also
precludes SVG files with script, multipage PDF files, interactive
MNG files, HTML documents, plain text documents, and so forth.</p>
<p>The requirements on the <code title="attr-img-alt">alt</code>
attribute's value are described <a href="#alt">in the next
section</a>.</p>
<p>The <code>img</code> must not be used as a layout tool. In
particular, <code>img</code> elements should not be used to display
transparent images, as they rarely convey meaning and rarely add
anything useful to the document.</p>
<div class="impl">
<hr>
<p>Unless the user agent cannot support images, or its support for
images has been disabled, or the user agent only fetches elements on
demand, or the element's <code title="attr-img-src">src</code>
attribute has a value that is an <i>ignored self-reference</i>,
then, when an <code>img</code> is created with a <code
title="attr-img-src">src</code> attribute, and whenever the <code
title="attr-img-src">src</code> attribute is set subsequently, the
user agent must <span title="resolve a url">resolve</span> the value
of that attribute, relative to the element, and if that is
successful must then <span>fetch</span> that resource.</p> <!-- Note
how this does NOT happen when the base URL changes. --> <!--
http-origin privacy sensitive -->
<p>The <code title="attr-img-src">src</code> attribute's value is an
<i>ignored self-reference</i> if its value is the empty string, and
the <i>base URI of the element</i> is the same as <span>the
document's address</span>.</p>
<!-- same text in <input type=image> section and similar text elsewhere -->
<p>Fetching the image must <span>delay the load event</span> of the
element's document until the <span title="concept-task">task</span>
that is <span title="queue a task">queued</span> by the
<span>networking task source</span> once the resource has been <span
title="fetch">fetched</span> (defined below) has been run.</p>
<p class="warning">This, unfortunately, can be used to perform a
rudimentary port scan of the user's local network (especially in
conjunction with scripting, though scripting isn't actually
necessary to carry out such an attack). User agents may implement
<span title="origin">cross-origin</span> access control policies
that mitigate this attack.</p>
<p>If the image is in a supported image type and its dimensions are
known, then the image is said to be <dfn
title="img-available"><i>available</i></dfn> (this affects exactly
what the element represents, as defined below). This can be true
even before the image is completely downloaded, if the user agent
supports incremental rendering of images; in such cases, each <span
title="concept-task">task</span> that is <span title="queue a
task">queued</span> by the <span>networking task source</span> while
the image is being <span title="fetch">fetched</span> must update
the presentation of the image appropriately. It can also stop being
true, e.g. if the user agent finds, after obtaining the image's
dimensions, that the image data is actually fatally corrupted.</p>
<p>If the image was not fetched (e.g. because the UA's image support
is disabled, or because the <code title="attr-img-src">src</code>
attribute's value is an <i>ignored self-reference</i>), or if the
conditions in the previous paragraph are not met, then the image is
<em>not</em> <i title="img-available">available</i>.</p>
<p class="note">An image might be <i
title="img-available">available</i> in one <span>view</span> but not
another. For instance, a <code>Document</code> could be rendered by
a screen reader providing a speech synthesis view of the output of a
Web browser using the screen media. In this case, the image would be
<i title="img-available">available</i> in the Web browser's screen
view, but <em>not</em> <i title="img-available">available</i> in the
screen reader's view.</p>
<p>Whether the image is fetched successfully or not (e.g. whether
the response code was a 2xx code <span
title="concept-http-equivalent-codes">or equivalent</span>) must be
ignored when determining the image's type and whether it is a valid
image.</p>
<p class="note">This allows servers to return images with error
responses, and have them displayed.</p>
<p>The user agents should apply the <span title="Content-Type
sniffing: image">image sniffing rules</span> to determine the type
of the image, with the image's <span title="Content-Type">associated
Content-Type headers</span> giving the <var title="">official
type</var>. If these rules are not applied, then the type of the
image must be the type given by the image's <span
title="Content-Type">associated Content-Type headers</span>.</p>
<p>User agents must not support non-image resources with the
<code>img</code> element (e.g. XML files whose root element is an
HTML element). User agents must not run executable code
(e.g. scripts) embedded in the image resource. User agents must only
display the first page of a multipage resource (e.g. a PDF
file). User agents must not allow the resource to act in an
interactive fashion, but should honor any animation in the
resource.</p>
<p>This specification does not specify which image types are to be
supported.</p>
<p>The <span title="concept-task">task</span> that is <span
title="queue a task">queued</span> by the <span>networking task
source</span> once the resource has been <span
title="fetch">fetched</span>, must act as appropriate given the
following alternatives:</p>
<dl class="switch">
<dt>If the download was successful and the image is <i
title="img-available">available</i></dt>
<dd><span>Queue a task</span> to <span>fire a simple event</span>
named <code title="event-load">load</code> at the <code>img</code>
element (this happens after <code
title="dom-img-complete">complete</code> starts returning
true).</dd>
<dt>Otherwise (the fetching process failed without a response from
the remote server, or completed but the image is not a supported
image)</dt>
<dd><span>Queue a task</span> to <span>fire a simple event</span>
named <code title="event-error">error</code> on the
<code>img</code> element.</dd>
</dl>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <span>DOM manipulation
task source</span>.</p>
<hr>
<p>What an <code>img</code> element represents depends on the <code
title="attr-img-src">src</code> attribute and the <code
title="attr-img-alt">alt</code> attribute.</p>
<dl class="switch">
<dt>If the <code title="attr-img-src">src</code> attribute is set
and the <code title="attr-img-alt">alt</code> attribute is set to
the empty string</dt>
<dd>
<p>The image is either decorative or supplemental to the rest of
the content, redundant with some other information in the
document.</p>
<p>If the image is <i title="img-available">available</i> and the
user agent is configured to display that image, then the element
<span>represents</span> the image specified by the <code
title="attr-img-src">src</code> attribute.</p>
<p>Otherwise, the element <span>represents</span> nothing, and may
be omitted completely from the rendering. User agents may provide
the user with a notification that an image is present but has been
omitted from the rendering.</p>
</dd>
<dt>If the <code title="attr-img-src">src</code> attribute is set
and the <code title="attr-img-alt">alt</code> attribute is set to a
value that isn't empty</dt>
<dd>
<p>The image is a key part of the content; the <code
title="attr-img-alt">alt</code> attribute gives a textual
equivalent or replacement for the image.</p>
<p>If the image is <i title="img-available">available</i> and the
user agent is configured to display that image, then the element
<span>represents</span> the image specified by the <code
title="attr-img-src">src</code> attribute.</p>
<p>Otherwise, the element <span>represents</span> the text given
by the <code title="attr-img-alt">alt</code> attribute. User
agents may provide the user with a notification that an image is
present but has been omitted from the rendering.</p>
</dd>
<dt>If the <code title="attr-img-src">src</code> attribute is set
and the <code title="attr-img-alt">alt</code> attribute is not</dt>
<dd>
<p>The image might be a key part of the content, and there is no
textual equivalent of the image available.</p>
<p class="note">In a conforming document, the absence of the <code
title="attr-img-alt">alt</code> attribute indicates that the image
is a key part of the content but that a textual replacement for
the image was not available when the image was generated.</p>
<p>If the image is <i title="img-available">available</i>, the
element <span>represents</span> the image specified by the <code
title="attr-img-src">src</code> attribute.</p>
<p>If the image is not <i title="img-available">available</i> or
if the user agent is not configured to display the image, then the
user agent should display some sort of indicator that there is an
image that is not being rendered, and may, if requested by the
user, or if so configured, or when required to provide contextual
information in response to navigation, provide caption information
for the image, derived as follows:</p>
<ol>
<li><p>If the image has a <code title="attr-title">title</code>
attribute whose value is not the empty string, then the value of
that attribute is the caption information; abort these
steps.</p></li>
<li><p>If the image is the child of a <code>figure</code> element
that has a child <code>dt</code> element, then the contents of
the first such <code>dt</code> element are the caption
information; abort these steps.</p></li>
<li><p>Run the algorithm to create the <span>outline</span> for
the document.</p></li>
<li><p>If the <code>img</code> element did not end up associated
with a heading in the outline, or if there are any other images
that are lacking an <code title="attr-img-alt">alt</code>
attribute and that are associated with the same heading in the
outline as the <code>img</code> element in question, then there
is no caption information; abort these steps.</p></li>
<li><p>The caption information is the heading with which the
image is associated according to the outline.</p></li>
</ol>
</dd>
<dt>If the <code title="attr-img-src">src</code> attribute is not
set and either the <code title="attr-img-alt">alt</code> attribute
is set to the empty string or the <code
title="attr-img-alt">alt</code> attribute is not set at all</dt>
<dd>
<p>The element <span>represents</span> nothing.</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p>The element <span>represents</span> the text given by the <code
title="attr-img-alt">alt</code> attribute.</p>
</dd>
</dl>
<p>The <code title="attr-img-alt">alt</code> attribute does not
represent advisory information. User agents must not present the
contents of the <code title="attr-img-alt">alt</code> attribute in
the same way as content of the <code title="attr-title">title</code>
attribute.</p>
<p>User agents may always provide the user with the option to
display any image, or to prevent any image from being
displayed. User agents may also apply image analysis heuristics to
help the user make sense of the image when the user is unable to
make direct use of the image, e.g. due to a visual disability or
because they are using a text terminal with no graphics
capabilities.</p>
<p>The <em>contents</em> of <code>img</code> elements, if any, are
ignored for the purposes of rendering.</p>
</div>
<hr>
<p>The <code title="attr-hyperlink-usemap">usemap</code> attribute,
if present, can indicate that the image has an associated
<span>image map</span>.</p>
<p>The <dfn title="attr-img-ismap"><code>ismap</code></dfn>
attribute, when used on an element that is a descendant of an
<code>a</code> element with an <code
title="attr-hyperlink-href">href</code> attribute, indicates by its
presence that the element provides access to a server-side image
map. This affects how events are handled on the corresponding
<code>a</code> element.</p>
<p>The <code title="attr-img-ismap">ismap</code> attribute is a
<span>boolean attribute</span>. The attribute must not be specified
on an element that does not have an ancestor <code>a</code> element
with an <code title="attr-hyperlink-href">href</code> attribute.</p>
<p>The <code>img</code> element supports <span>dimension
attributes</span>.</p>
<div class="impl">
<p>The IDL attributes <dfn
title="dom-img-alt"><code>alt</code></dfn>, <dfn
title="dom-img-src"><code>src</code></dfn>, <dfn
title="dom-img-useMap"><code>useMap</code></dfn>, and <dfn
title="dom-img-isMap"><code>isMap</code></dfn> each must
<span>reflect</span> the respective content attributes of the same
name.</p>
</div>
<dl class="domintro">
<dt><var title="">image</var> . <code title="dom-img-width">width</code> [ = <var title="">value</var> ]</dt>
<dt><var title="">image</var> . <code title="dom-img-height">height</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>These attributes return the actual rendered dimensions of the
image, or zero if the dimensions are not known.</p>
<p>They can be set, to change the corresponding content
attributes.</p>
</dd>
<dt><var title="">image</var> . <code title="dom-img-naturalWidth">naturalWidth</code></dt>
<dt><var title="">image</var> . <code title="dom-img-naturalHeight">naturalHeight</code></dt>
<dd>
<p>These attributes return the intrinsic dimensions of the image,
or zero if the dimensions are not known.</p>
</dd>
<dt><var title="">image</var> . <code title="dom-img-complete">complete</code></dt>
<dd>
<p>Returns true if the image has been downloaded, decoded, and
found to be valid; otherwise, returns false.</p>
</dd>
<dt><var title="">image</var> = new <code title="dom-image">Image</code>( [ <var title="">width</var> [, <var title="">height</var> ] ] )</dt>
<dd>
<p>Returns a new <code>img</code> element, with the <code
title="attr-dim-width">width</code> and <code
title="attr-dim-height">height</code> attributes set to the values
passed in the relevant arguments, if applicable.</p>
</dd>
</dl>
<div class="impl">
<p>The IDL attributes <dfn
title="dom-img-width"><code>width</code></dfn> and <dfn
title="dom-img-height"><code>height</code></dfn> must return the
rendered width and height of the image, in CSS pixels, if the image
is <span>being rendered</span>, and is being rendered to a visual
medium; or else the intrinsic width and height of the image, in CSS
pixels, if the image is <i title="img-available">available</i> but
not being rendered to a visual medium; or else 0, if the image is
not <i title="img-available">available</i>. <a
href="#refsCSS">[CSS]</a></p>
<p>On setting, they must act as if they <span
title="reflect">reflected</span> the respective content attributes
of the same name.</p>
<p>The IDL attributes <dfn
title="dom-img-naturalWidth"><code>naturalWidth</code></dfn> and
<dfn title="dom-img-naturalHeight"><code>naturalHeight</code></dfn>
must return the intrinsic width and height of the image, in CSS
pixels, if the image is <i title="img-available">available</i>, or
else 0. <a href="#refsCSS">[CSS]</a></p>
<p>The IDL attribute <dfn
title="dom-img-complete"><code>complete</code></dfn> must return
true if the user agent has fetched the image specified in the <code
title="attr-img-src">src</code> attribute, and it is in a supported
image type (i.e. it was decoded without fatal errors), even if the
final <span title="concept-task">task</span> queued by the
<span>networking task source</span> for the <span
title="fetch">fetching</span> of the image resource has not yet been
processed. Otherwise, the attribute must return false.</p>
<p class="note">The value of <code
title="dom-img-complete">complete</code> can thus change while a
<span title="concept-script">script</span> is executing.</p>
<p>Three constructors are provided for creating
<code>HTMLImageElement</code> objects (in addition to the factory
methods from DOM Core such as <code
title="">createElement()</code>): <dfn
title="dom-image"><code>Image()</code></dfn>, <dfn
title="dom-image-w"><code>Image(<var
title="">width</var>)</code></dfn>, and <dfn
title="dom-image-wh"><code>Image(<var title="">width</var>, <var
title="">height</var>)</code></dfn>. When invoked as constructors,
these must return a new <code>HTMLImageElement</code> object (a new
<code>img</code> element). If the <var title="">width</var> argument
is present, the new object's <code
title="attr-dim-width">width</code> content attribute must be set to
<var title="">width</var>. If the <var title="">height</var>
argument is also present, the new object's <code
title="attr-dim-height">height</code> content attribute must be set
to <var title="">height</var>. The element's document must be the
<span>active document</span> of the <span>browsing context</span> of
the <code>Window</code> object on which the interface object of the
invoked constructor is found.</p>
</div>
<div class="example">
<p>A single image can have different appropriate alternative text
depending on the context.</p>
<p>In each of the following cases, the same image is used, yet the
<code title="attr-img-alt">alt</code> text is different each
time. The image is the coat of arms of the Carouge municipality in
the canton Geneva in Switzerland.</p>
<p>Here it is used as a supplementary icon:</p>
<pre><p>I lived in <img src="carouge.svg" alt=""> Carouge.</p></pre>
<p>Here it is used as an icon representing the town:</p>
<pre><p>Home town: <img src="carouge.svg" alt="Carouge"></p></pre>
<p>Here it is used as part of a text on the town:</p>
<pre><p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt="The coat of arms depicts a lion, sitting in front of a tree."></p>
<p>It is used as decoration all over the town.</p></pre>
<p>Here it is used as a way to support a similar text where the
description is given as well as, instead of as an alternative to,
the image:</p>
<pre><p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt=""></p>
<p>The coat of arms depicts a lion, sitting in front of a tree.
It is used as decoration all over the town.</p></pre>
<p>Here it is used as part of a story:</p>
<pre><p>He picked up the folder and a piece of paper fell out.</p>
<p><img src="carouge.svg" alt="Shaped like a shield, the paper had a
red background, a green tree, and a yellow lion with its tongue
hanging out and whose tail was shaped like an S."></p>
<p>He stared at the folder. S! The answer he had been looking for all
this time was simply the letter S! How had he not seen that before? It all
came together now. The phone call where Hector had referred to a lion's tail,
the time Marco had stuck his tongue out...</p></pre>
<p>Here it is not known at the time of publication what the image
will be, only that it will be a coat of arms of some kind, and thus
no replacement text can be provided, and instead only a brief
caption for the image is provided, in the <code
title="attr-title">title</code> attribute:</p>
<pre><p>The last user to have uploaded a coat of arms uploaded this one:</p>
<p><img src="last-uploaded-coat-of-arms.cgi" title="User-uploaded coat of arms."></p></pre>
<p>Ideally, the author would find a way to provide real replacement
text even in this case, e.g. by asking the previous user. Not
providing replacement text makes the document more difficult to use
for people who are unable to view images, e.g. blind users, or
users or very low-bandwidth connections or who pay by the byte, or
users who are forced to use a text-only Web browser.</p>
</div>
<div class="example">
<p>Here are some more examples showing the same picture used in
different contexts, with different appropriate alternate texts each
time.</p>
<pre><article>
<h1>My cats</h1>
<h2>Fluffy</h2>
<p>Fluffy is my favorite.</p>
<img src="fluffy.jpg" alt="She likes playing with a ball of yarn.">
<p>She's just too cute.</p>
<h2>Miles</h2>
<p>My other cat, Miles just eats and sleeps.</p>
</article></pre>
<pre><article>
<h1>Photography</h1>
<h2>Shooting moving targets indoors</h2>
<p>The trick here is to know how to anticipate; to know at what speed and
what distance the subject will pass by.</p>
<img src="fluffy.jpg" alt="A cat flying by, chasing a ball of yarn, can be
photographed quite nicely using this technique.">
<h2>Nature by night</h2>
<p>To achieve this, you'll need either an extremely sensitive film, or
immense flash lights.</p>
</article></pre>
<pre><article>
<h1>About me</h1>
<h2>My pets</h2>
<p>I've got a cat named Fluffy and a dog named Miles.</p>
<img src="fluffy.jpg" alt="Fluffy, my cat, tends to keep itself busy.">
<p>My dog Miles and I like go on long walks together.</p>
<h2>music</h2>
<p>After our walks, having emptied my mind, I like listening to Bach.</p>
</article></pre>
<pre><article>
<h1>Fluffy and the Yarn</h1>
<p>Fluffy was a cat who liked to play with yarn. He also liked to jump.</p>
<aside><img src="fluffy.jpg" alt="" title="Fluffy"></aside>
<p>He would play in the morning, he would play in the evening.</p>
</article></pre>
</div>
<h5 id="alt">Requirements for providing text to act as an alternative for images</h5>
<p>The requirements for the <code title="attr-img-alt">alt</code>
attribute depend on what the image is intended to represent, as
described in the following sections.</p>
<h6>A link or button containing nothing but the image</h6>
<p>When an <span>a</span> element that is a <span>hyperlink</span>,
or a <code>button</code> element, has no textual content but
contains one or more images, the <code
title="attr-img-alt">alt</code> attributes must contain text that
together convey the purpose of the link or button.</p>
<div class="example">
<p>In this example, a user is asked to pick his preferred color
from a list of three. Each color is given by an image, but for
users who have configured their user agent not to display images,
the color names are used instead:</p>
<pre><h1>Pick your color</h1>
<ul>
<li><a href="green.html"><strong><img src="green.jpeg" alt="Green"></strong></a></li>
<li><a href="blue.html"><strong><img src="blue.jpeg" alt="Blue"></strong></a></li>
<li><a href="red.html"><strong><img src="red.jpeg" alt="Red"></strong></a></li>
</ul></pre>
</div>
<div class="example">
<p>In this example, each button has a set of images to indicate the
kind of color output desired by the user. The first image is used
in each case to give the alternative text.</p>
<pre><button name="rgb"><strong><img src="red" alt="RGB"><img src="green" alt=""><img src="blue" alt=""></strong></button>
<button name="cmyk"><strong><img src="cyan" alt="CMYK"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></strong></button></pre>
<p>Since each image represents one part of the text, it could also
be written like this:</p>
<pre><button name="rgb"><strong><img src="red" alt="R"><img src="green" alt="G"><img src="blue" alt="B"></strong></button>
<button name="cmyk"><strong><img src="cyan" alt="C"><img src="magenta" alt="M"><img src="yellow" alt="Y"><img src="black" alt="K"></strong></button></pre>
<p>However, with other alternative text, this might not work, and
putting all the alternative text into one image in each case might
make more sense:</p>
<pre><button name="rgb"><strong><img src="red" alt="sRGB profile"><img src="green" alt=""><img src="blue" alt=""></strong></button>
<button name="cmyk"><strong><img src="cyan" alt="CMYK profile"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></strong></button></pre>
</div>
<h6>A phrase or paragraph with an alternative graphical representation: charts, diagrams, graphs, maps, illustrations</h6>
<p>Sometimes something can be more clearly stated in graphical
form, for example as a flowchart, a diagram, a graph, or a simple
map showing directions. In such cases, an image can be given using
the <code>img</code> element, but the lesser textual version must
still be given, so that users who are unable to view the image
(e.g. because they have a very slow connection, or because they
are using a text-only browser, or because they are listening to
the page being read out by a hands-free automobile voice Web
browser, or simply because they are blind) are still able to
understand the message being conveyed.</p>
<p>The text must be given in the <code
title="attr-img-alt">alt</code> attribute, and must convey the
same message as the image specified in the <code
title="attr-img-src">src</code> attribute.</p>
<p>It is important to realize that the alternative text is a
<em>replacement</em> for the image, not a description of the
image.</p>
<div class="example">
<p>In the following example we have <a
href="images/parsing-model-overview.png">a flowchart</a> in image
form, with text in the <code title="attr-img-alt">alt</code>
attribute rephrasing the flowchart in prose form:</p>
<pre><p>In the common case, the data handled by the tokenization stage
comes from the network, but it can also come from script.</p>
<p><strong><img src="images/parsing-model-overview.png" alt="The network
passes data to the Tokenizer stage, which passes data to the Tree
Construction stage. From there, data goes to both the DOM and to
Script Execution. Script Execution is linked to the DOM, and, using
document.write(), passes data to the Tokenizer."></strong></p></pre>
</div>
<div class="example">
<p>Here's another example, showing a good solution and a bad
solution to the problem of including an image in a
description.</p>
<p>First, here's the good solution. This sample shows how the
alternative text should just be what you would have put in the
prose if the image had never existed.</p>
<pre><!-- This is the correct way to do things. -->
<p>
You are standing in an open field west of a house.
<strong><img src="house.jpeg" alt="The house is white, with a boarded front door."></strong>
There is a small mailbox here.
</p></pre>
<p>Second, here's the bad solution. In this incorrect way of
doing things, the alternative text is simply a description of the
image, instead of a textual replacement for the image. It's bad
because when the image isn't shown, the text doesn't flow as well
as in the first example.</p>
<pre class="bad"><!-- <em>This is the wrong way to do things.</em> -->
<p>
You are standing in an open field west of a house.
<img src="house.jpeg" alt="A white house, with a boarded front door.">
There is a small mailbox here.
</p></pre>
<p>Text such as "Photo of white house with boarded door" would be
equally bad alternative text (though it could be suitable for the
<code title="attr-title">title</code> attribute or in the
<code>dt</code> element of a <code>figure</code> with this
image).</p>
</div>
<h6>A short phrase or label with an alternative graphical representation: icons, logos</h6>
<p>A document can contain information in iconic form. The icon is
intended to help users of visual browsers to recognize features at
a glance.</p>
<p>In some cases, the icon is supplemental to a text label
conveying the same meaning. In those cases, the <code
title="attr-img-alt">alt</code> attribute must be present but must
be empty.</p>
<div class="example">
<p>Here the icons are next to text that conveys the same meaning,
so they have an empty <code title="attr-img-alt">alt</code>
attribute:</p>
<pre><nav>
<p><a href="/help/"><strong><img src="/icons/help.png" alt=""></strong> Help</a></p>
<p><a href="/configure/"><strong><img src="/icons/configuration.png" alt=""></strong>
Configuration Tools</a></p>
</nav></pre>
</div>
<p>In other cases, the icon has no text next to it describing what
it means; the icon is supposed to be self-explanatory. In those
cases, an equivalent textual label must be given in the <code
title="attr-img-alt">alt</code> attribute.</p>
<div class="example">
<p>Here, posts on a news site are labeled with an icon
indicating their topic.</p>
<pre><body>
<article>
<header>
<h1>Ratatouille wins <i>Best Movie of the Year</i> award</h1>
<p><strong><img src="movies.png" alt="Movies"></strong></p>
</header>
<p>Pixar has won yet another <i>Best Movie of the Year</i> award,
making this its 8th win in the last 12 years.</p>
</article>
<article>
<header>
<h1>Latest TWiT episode is online</h1>
<p><strong><img src="podcasts.png" alt="Podcasts"></strong></p>
</header>
<p>The latest TWiT episode has been posted, in which we hear
several tech news stories as well as learning much more about the
iPhone. This week, the panelists compare how reflective their
iPhones' Apple logos are.</p>
</article>
</body></pre>
</div>
<p>Many pages include logos, insignia, flags, or emblems, which
stand for a particular entity such as a company, organization,
project, band, software package, country, or some such.</p>
<p>If the logo is being used to represent the entity, e.g. as a page
heading, the <code title="attr-img-alt">alt</code> attribute must
contain the name of the entity being represented by the logo. The
<code title="attr-img-alt">alt</code> attribute must <em>not</em>
contain text like the word "logo", as it is not the fact that it is
a logo that is being conveyed, it's the entity itself.</p>
<p>If the logo is being used next to the name of the entity that
it represents, then the logo is supplemental, and its <code
title="attr-img-alt">alt</code> attribute must instead be
empty.</p>
<p>If the logo is merely used as decorative material (as branding,
or, for example, as a side image in an article that mentions the
entity to which the logo belongs), then the entry below on purely
decorative images applies. If the logo is actually being
discussed, then it is being used as a phrase or paragraph (the
description of the logo) with an alternative graphical
representation (the logo itself), and the first entry above
applies.</p>
<div class="example">
<p>In the following snippets, all four of the above cases are
present. First, we see a logo used to represent a company:</p>
<pre><h1><strong><img src="XYZ.gif" alt="The XYZ company"></strong></h1></pre>
<p>Next, we see a paragraph which uses a logo right next to the
company name, and so doesn't have any alternative text:
<pre><article>
<h2>News</h2>
<p>We have recently been looking at buying the <strong><img src="alpha.gif"
alt=""> ΑΒΓ company</strong>, a small Greek company
specializing in our type of product.</p></pre>
<p>In this third snippet, we have a logo being used in an aside,
as part of the larger article discussing the acquisition:</p>
<pre> <strong><aside><p><img src="alpha-large.gif" alt=""></p></aside></strong>
<p>The ΑΒΓ company has had a good quarter, and our
pie chart studies of their accounts suggest a much bigger blue slice
than its green and orange slices, which is always a good sign.</p>
</article></pre>
<p>Finally, we have an opinion piece talking about a logo, and
the logo is therefore described in detail in the alternative
text.</p>
<pre><p>Consider for a moment their logo:</p>
<strong><p><img src="/images/logo" alt="It consists of a green circle with a
green question mark centered inside it."></p></strong>
<p>How unoriginal can you get? I mean, oooooh, a question mark, how
<em>revolutionary</em>, how utterly <em>ground-breaking</em>, I'm
sure everyone will rush to adopt those specifications now! They could
at least have tried for some sort of, I don't know, sequence of
rounded squares with varying shades of green and bold white outlines,
at least that would look good on the cover of a blue book.</p></pre>
<p>This example shows how the alternative text should be written
such that if the image isn't <i
title="img-available">available</i>, and the text is used instead,
the text flows seamlessly into the surrounding text, as if the
image had never been there in the first place.</p>
</div>
<h6>Text that has been rendered to a graphic for typographical effect</h6>
<p>Sometimes, an image just consists of text, and the purpose of the
image is not to highlight the actual typographic effects used to
render the text, but just to convey the text itself.</p>
<p>In such cases, the <code title="attr-img-alt">alt</code>
attribute must be present but must consist of the same text as
written in the image itself.</p>
<div class="example">
<p>Consider a graphic containing the text "Earth Day", but with the
letters all decorated with flowers and plants. If the text is
merely being used as a heading, to spice up the page for graphical
users, then the correct alternative text is just the same text
"Earth Day", and no mention need be made of the decorations:</p>
<pre><h1><strong><img src="earthdayheading.png" alt="Earth Day"></strong></h1></pre>
</div>
<h6>A graphical representation of some of the surrounding text</h6>
<p>In many cases, the image is actually just supplementary, and
its presence merely reinforces the surrounding text. In these
cases, the <code title="attr-img-alt">alt</code> attribute must be
present but its value must be the empty string.</p>
<p>In general, an image falls into this category if removing the
image doesn't make the page any less useful, but including the
image makes it a lot easier for users of visual browsers to
understand the concept.</p>
<div class="example">
<p>A flowchart that repeats the previous paragraph in graphical form:</p>
<pre><p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<strong><p><img src="images/parsing-model-overview.png" alt=""></p></strong></pre>
<p>In these cases, it would be wrong to include alternative text
that consists of just a caption. If a caption is to be included,
then either the <code title="attr-title">title</code> attribute can
be used, or the <code>figure</code> and <code>dt</code> elements
can be used. In the latter case, the image would in fact be a
phrase or paragraph with an alternative graphical representation,
and would thus require alternative text.</p>
<pre><!-- Using the title="" attribute -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<p><strong><img src="images/parsing-model-overview.png" alt=""
title="Flowchart representation of the parsing model."></strong></p></pre>
<pre><!-- Using <figure> and <dt> -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<figure>
<dd>
<strong><img src="images/parsing-model-overview.png" alt="The Network leads
to the Tokenizer, which leads to the Tree Construction. The Tree
Construction leads to two items. The first is Script Execution, which
leads via document.write() back to the Tokenizer. The second item
from which Tree Construction leads is the DOM. The DOM is related to
the Script Execution."></strong>
</dd>
<dt>Flowchart representation of the parsing model.</dt>
</figure></pre>
<pre class="bad"><!-- This is WRONG. Do not do this. Instead, do what the above examples do. -->
<p>The network passes data to the Tokenizer stage, which
passes data to the Tree Construction stage. From there, data goes
to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to
the Tokenizer.</p>
<p><img src="images/parsing-model-overview.png"
alt="Flowchart representation of the parsing model."></p>
<!-- Never put the image's caption in the alt="" attribute! --></pre>
</div>
<div class="example">
<p>A graph that repeats the previous paragraph in graphical form:</p>
<pre><p>According to a study covering several billion pages,
about 62% of documents on the Web in 2007 triggered the Quirks
rendering mode of Web browsers, about 30% triggered the Almost
Standards mode, and about 9% triggered the Standards mode.</p>
<strong><p><img src="rendering-mode-pie-chart.png" alt=""></p></strong></pre>
</div>
<h6>A purely decorative image that doesn't add any information</h6>
<p>In general, if an image is decorative but isn't especially
page-specific, for example an image that forms part of a site-wide
design scheme, the image should be specified in the site's CSS,
not in the markup of the document.</p>
<p>However, a decorative image that isn't discussed by the
surrounding text still has some relevance can be included in a page
using the <code>img</code> element. Such images are decorative, but
still form part of the content. In these cases, the <code
title="attr-img-alt">alt</code> attribute must be present but its
value must be the empty string.</p>
<div class="example">
<p>Examples where the image is purely decorative despite being
relevant would include things like a photo of the Black Rock City
landscape in a blog post about an event at Burning Man, or an
image of a painting inspired by a poem, on a page reciting that
poem. The following snippet shows an example of the latter
case (only the first verse is included in this snippet):</p>
<pre><h1>The Lady of Shalott</h1>
<strong><p><img src="shalott.jpeg" alt=""></p></strong>
<p>On either side the river lie<br>
Long fields of barley and of rye,<br>
That clothe the wold and meet the sky;<br>
And through the field the road run by<br>
To many-tower'd Camelot;<br>
And up and down the people go,<br>
Gazing where the lilies blow<br>
Round an island there below,<br>
The island of Shalott.</p></pre>
</div>
<h6>A group of images that form a single larger picture with no links</h6>
<p>When a picture has been sliced into smaller image files that are
then displayed together to form the complete picture again, one of
the images must have its <code title="attr-img-alt">alt</code>
attribute set as per the relevant rules that would be appropriate
for the picture as a whole, and then all the remaining images must
have their <code title="attr-img-alt">alt</code> attribute set to
the empty string.</p>
<div class="example">
<p>In the following example, a picture representing a company logo
for <span title="">XYZ Corp</span> has been split into two pieces,
the first containing the letters "XYZ" and the second with the word
"Corp". The alternative text ("XYZ Corp") is all in the first
image.</p>
<pre><h1><strong><img src="logo1.png" alt="XYZ Corp"><img src="logo2.png" alt=""></strong></h1></pre>
</div>
<div class="example">
<p>In the following example, a rating is shown as three filled
stars and two empty stars. While the alternative text could have
been "★★★☆☆", the author has
instead decided to more helpfully give the rating in the form "3
out of 5". That is the alternative text of the first image, and the
rest have blank alternative text.</p>
<pre><p>Rating: <meter max=5 value=3><strong><img src="1" alt="3 out of 5"
><img src="1" alt=""><img src="1" alt=""><img src="0" alt=""
><img src="0" alt=""></strong></meter></p></pre>
</div>
<h6>A group of images that form a single larger picture with links</h6>
<p>Generally, <span title="image map">image maps</span> should be
used instead of slicing an image for links.</p>
<p>However, if an image is indeed sliced and any of the components
of the sliced picture are the sole contents of links, then one image
per link must have alternative text in its <code
title="attr-img-alt">alt</code> attribute representing the purpose
of the link.</p>
<div class="example">
<p>In the following example, a picture representing the flying
spaghetti monster emblem, with each of the left noodly appendages
and the right noodly appendages in different images, so that the
user can pick the left side or the right side in an adventure.</p>
<pre><h1>The Church</h1>
<p>You come across a flying spaghetti monster. Which side of His
Noodliness do you wish to reach out for?</p>
<strong><p><a href="?go=left" ><img src="fsm-left.png" alt="Left side. "></a
><img src="fsm-middle.png" alt=""
><a href="?go=right"><img src="fsm-right.png" alt="Right side."></a></p></strong></pre>
</div>
<h6>A key part of the content</h6>
<p>In some cases, the image is a critical part of the
content. This could be the case, for instance, on a page that is
part of a photo gallery. The image is the whole <em>point</em> of
the page containing it.</p>
<p>How to provide alternative text for an image that is a key part
of the content depends on the image's provenance.</p>
<dl>
<dt>The general case</dt>
<dd>
<p>When it is possible for detailed alternative text to be
provided, for example if the image is part of a series of
screenshots in a magazine review, or part of a comic strip, or is
a photograph in a blog entry about that photograph, text that can
serve as a substitute for the image must be given as the contents
of the <code title="attr-img-alt">alt</code> attribute.</p>
<div class="example">
<p>A screenshot in a gallery of screenshots for a new OS, with
some alternative text:</p>
<pre><figure>
<dd>
<strong><img src="KDE%20Light%20desktop.png"
alt="The desktop is blue, with icons along the left hand side in
two columns, reading System, Home, K-Mail, etc. A window is
open showing that menus wrap to a second line if they
cannot fit in the window. The window has a list of icons
along the top, with an address bar below it, a list of
icons for tabs along the left edge, a status bar on the
bottom, and two panes in the middle. The desktop has a bar
at the bottom of the screen with a few buttons, a pager, a
list of open applications, and a clock."></strong>
</dd>
<dt>Screenshot of a KDE desktop.</dt>
</figure></pre>
</div>
<div class="example">
<p>A graph in a financial report:</p>
<pre><strong><img src="sales.gif"
title="Sales graph"
alt="From 1998 to 2005, sales increased by the following percentages
with each year: 624%, 75%, 138%, 40%, 35%, 9%, 21%"></strong></pre>
<p>Note that "sales graph" would be inadequate alternative text
for a sales graph. Text that would be a good <em>caption</em> is
not generally suitable as replacement text.</p>
</div>
</dd>
<dt>Images that defy a complete description</dt>
<dd>
<p>In certain cases, the nature of the image might be such that
providing thorough alternative text is impractical. For example,
the image could be indistinct, or could be a complex fractal, or
could be a detailed topographical map.</p>
<p>In these cases, the <code title="attr-img-alt">alt</code>
attribute must contain some suitable alternative text, but it may
be somewhat brief.</p>
<div class="example">
<p>Sometimes there simply is no text that can do justice to an
image. For example, there is little that can be said to usefully
describe a Rorschach inkblot test. However, a description, even
if brief, is still better than nothing:</p>
<pre><figure>
<dd><strong><img src="/commons/a/a7/Rorschach1.jpg" alt="A shape with left-right
symmetry with indistinct edges, with a small gap in the center, two
larger gaps offset slightly from the center, with two similar gaps
under them. The outline is wider in the top half than the bottom
half, with the sides extending upwards higher than the center, and
the center extending below the sides."></strong></dd>
<dt>A black outline of the first of the ten cards
in the Rorschach inkblot test.</dt>
</figure></pre>
<p>Note that the following would be a very bad use of alternative
text:</p>
<pre class="bad"><!-- This example is wrong. Do not copy it. -->
<figure>
<dd><img src="/commons/a/a7/Rorschach1.jpg" alt="A black outline
of the first of the ten cards in the Rorschach inkblot test."></dd>
<dt>A black outline of the first of the ten cards
in the Rorschach inkblot test.</dt>
</figure></pre>
<p>Including the caption in the alternative text like this isn't
useful because it effectively duplicates the caption for users
who don't have images, taunting them twice yet not helping them
any more than if they had only read or heard the caption
once.</p>
</div>
<div class="example">
<p>Another example of an image that defies full description is a
fractal, which, by definition, is infinite in detail.</p>
<p>The following example shows one possible way of providing
alternative text for the full view of an image of the Mandelbrot
set.</p>
<pre><strong><img src="ms1.jpeg" alt="The Mandelbrot set appears as a cardioid with
its cusp on the real axis in the positive direction, with a smaller
bulb aligned along the same center line, touching it in the negative
direction, and with these two shapes being surrounded by smaller bulbs
of various sizes."></strong></pre>
</div>
</dd>
<dt id="unknown-images">Images whose contents are not known</dt>
<dd>
<p>In some unfortunate cases, there might be no alternative text
available at all, either because the image is obtained in some
automated fashion without any associated alternative text (e.g. a
Webcam), or because the page is being generated by a script using
user-provided images where the user did not provide suitable or
usable alternative text (e.g. photograph sharing sites), or
because the author does not himself know what the images represent
(e.g. a blind photographer sharing an image on his blog).</p>
<p>In such cases, the <code title="attr-img-alt">alt</code>
attribute's value may be omitted, but one of the following
conditions must be met as well:</p>
<ul>
<li>The <code title="attr-title">title</code> attribute is
present and has a non-empty value.</li>
<li>The <code>img</code> element is in a <code>figure</code>
element that contains a <code>dt</code> element that contains
content other than <span>inter-element whitespace</span>.</li>
<li>The <code>img</code> element is part of the only
<span>paragraph</span> directly in its <span
title="concept-section">section</span>, and is the only
<code>img</code> element without an <code
title="attr-img-alt">alt</code> attribute in its section, and its
<span title="concept-section">section</span> has an associated
heading.</li>
</ul>
<p class="note">Such cases are to be kept to an absolute
minimum. If there is even the slightest possibility of the author
having the ability to provide real alternative text, then it would
not be acceptable to omit the <code title="attr-img-alt">alt</code>
attribute.</p>
<div class="example">
<p>A photo on a photo-sharing site, if the site received the
image with no metadata other than the caption:</p>
<pre><figure>
<dd><strong><img src="1100670787_6a7c664aef.jpg"></strong></dd>
<dt>Bubbles traveled everywhere with us.</dt>
</figure></pre>
<p>It could also be marked up like this:</p>
<pre><article>
<h1>Bubbles traveled everywhere with us.</h1>
<strong><img src="1100670787_6a7c664aef.jpg"></strong>
</article></pre>
<p>In either case, though, it would be better if a detailed
description of the important parts of the image obtained from the
user and included on the page.</p>
</div>
<div class="example">
<p>A blind user's blog in which a photo taken by the user is
shown. Initially, the user might not have any idea what the photo
he took shows:</p>
<pre><article>
<h1>I took a photo</h1>
<p>I went out today and took a photo!</p>
<figure>
<dd><strong><img src="photo2.jpeg"></strong></dd>
<dt>A photograph taken blindly from my front porch.</dt>
</figure>
</article></pre>
<p>Eventually though, the user might obtain a description of the
image from his friends and could then include alternative text:</p>
<pre><article>
<h1>I took a photo</h1>
<p>I went out today and took a photo!</p>
<figure>
<dd><strong><img src="photo2.jpeg" alt="The photograph shows my hummingbird
feeder hanging from the edge of my roof. It is half full, but there
are no birds around. In the background, out-of-focus trees fill the
shot. The feeder is made of wood with a metal grate, and it contains
peanuts. The edge of the roof is wooden too, and is painted white
with light blue streaks."></strong></dd>
<dt>A photograph taken blindly from my front porch.</dt>
</figure>
</article></pre>
</div>
<div class="example">
<p>Sometimes the entire point of the image is that a textual
description is not available, and the user is to provide the
description. For instance, the point of a CAPTCHA image is to see
if the user can literally read the graphic. Here is one way to
mark up a CAPTCHA (note the <code title="attr-title">title</code>
attribute):</p>
<pre><p><label>What does this image say?
<strong><img src="captcha.cgi?id=8934" title="CAPTCHA"></strong>
<input type=text name=captcha></label>
(If you cannot see the image, you can use an <a
href="?audio">audio</a> test instead.)</p></pre>
<p>Another example would be software that displays images and
asks for alternative text precisely for the purpose of then
writing a page with correct alternative text. Such a page could
have a table of images, like this:</p>
<pre><table>
<thead>
<tr> <th> Image <th> Description
<tbody>
<tr>
<td> <strong><img src="2421.png" title="Image 640 by 100, filename 'banner.gif'"></strong>
<td> <input name="alt2421">
<tr>
<td> <strong><img src="2422.png" title="Image 200 by 480, filename 'ad3.gif'"></strong>
<td> <input name="alt2422">
</table></pre>
<p>Notice that even in this example, as much useful information
as possible is still included in the <code
title="attr-title">title</code> attribute.</p>
</div>
<p class="note">Since some users cannot use images at all
(e.g. because they have a very slow connection, or because they
are using a text-only browser, or because they are listening to
the page being read out by a hands-free automobile voice Web
browser, or simply because they are blind), the <code
title="attr-img-alt">alt</code> attribute is only allowed to be
omitted rather than being provided with replacement text when no
alternative text is available and none can be made available, as
in the above examples. Lack of effort from the part of the author
is not an acceptable reason for omitting the <code
title="attr-img-alt">alt</code> attribute.</p>
</dd>
</dl>
<h6>An image not intended for the user</h6>
<p>Generally authors should avoid using <code>img</code> elements
for purposes other than showing images.</p>
<p>If an <code>img</code> element is being used for purposes other
than showing an image, e.g. as part of a service to count page
views, then the <code title="attr-img-alt">alt</code> attribute must
be the empty string.</p>
<p>In such cases, the <code title="attr-dim-width">width</code> and
<code title="attr-dim-height">height</code> attributes should both
be set to zero.</p>
<h6>An image in an e-mail or private document intended for a specific person who is known to be able to view images</h6>
<p><i>This section does not apply to documents that are publicly
accessible, or whose target audience is not necessarily personally
known to the author, such as documents on a Web site, e-mails sent
to public mailing lists, or software documentation.</i></p>
<p>When an image is included in a private communication (such as an
HTML e-mail) aimed at a specific person who is known to be able to
view images, the <code title="attr-img-alt">alt</code> attribute may
be omitted. However, even in such cases it is strongly recommended
that alternative text be included (as appropriate according to the
kind of image involved, as described in the above entries), so that
the e-mail is still usable should the user use a mail client that
does not support images, or should the document be forwarded on to
other users whose abilities might not include easily seeing
images.</p>
<h6>General guidelines</h6>
<p>The most general rule to consider when writing alternative text
is the following: <strong>the intent is that replacing every image
with the text of its <code title="attr-img-alt">alt</code> attribute
not change the meaning of the page</strong>.</p>
<p>So, in general, alternative text can be written by considering
what one would have written had one not been able to include the
image.</p>
<p>A corollary to this is that the <code
title="attr-img-alt">alt</code> attribute's value should never
contain text that could be considered the image's <em>caption</em>,
<em>title</em>, or <em>legend</em>. It is supposed to contain
replacement text that could be used by users <em>instead</em> of the
image; it is not meant to supplement the image. The <code
title="attr-title">title</code> attribute can be used for
supplemental information.</p>
<p class="note">One way to think of alternative text is to think
about how you would read the page containing the image to someone
over the phone, without mentioning that there is an image
present. Whatever you say instead of the image is typically a good
start for writing the alternative text.</p>
<div class="impl">
<h6>Guidance for markup generators</h6>
<p>Markup generators (such as WYSIWYG authoring tools) should,
wherever possible, obtain alternative text from their
users. However, it is recognized that in many cases, this will not
be possible.</p>
<p>For images that are the sole contents of links, markup generators
should examine the link target to determine the title of the target,
or the URL of the target, and use information obtained in this
manner as the alternative text.</p>
<p>As a last resort, implementors should either set the <code
title="attr-img-alt">alt</code> attribute to the empty string, under
the assumption that the image is a purely decorative image that
doesn't add any information but is still specific to the surrounding
content, or omit the <code title="attr-img-alt">alt</code> attribute
altogether, under the assumption that the image is a key part of the
content.</p>
<p>Markup generators should generally avoid using the image's own
file name as the alternative text.</p>
</diV>
<div class="impl">
<h6>Guidance for conformance checkers</h6>
<p>A conformance checker must report the lack of an <code
title="attr-img-alt">alt</code> attribute as an error unless either
the conditions listed above for <a href="#unknown-images">images
whose contents are not known</a> apply, or the conformance checker
has been configured to assume that the document is an e-mail or
document intended for a specific person who is known to be able to
view images, or the document has a <code>meta</code> element with a
<code title="attr-meta-name">name</code> attribute whose value is an
<span>ASCII case-insensitive</span> match for the string "<code
title="meta-generator">generator</code>".</p>
</div>
<h4>The <dfn><code>iframe</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Embedded content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>embedded content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Text that conforms to the requirements given in the prose.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-iframe-src">src</code></dd>
<dd><code title="attr-iframe-name">name</code></dd>
<dd><code title="attr-iframe-sandbox">sandbox</code></dd>
<dd><code title="attr-iframe-seamless">seamless</code></dd>
<dd><code title="attr-dim-width">width</code></dd>
<dd><code title="attr-dim-height">height</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLIFrameElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-iframe-src">src</span>;
attribute DOMString <span title="dom-iframe-name">name</span>;
attribute DOMString <span title="dom-iframe-sandbox">sandbox</span>;
attribute boolean <span title="dom-iframe-seamless">seamless</span>;
attribute DOMString <span title="dom-dim-width">width</span>;
attribute DOMString <span title="dom-dim-height">height</span>;
readonly attribute Document <span title="dom-iframe-contentDocument">contentDocument</span>;
readonly attribute <span>WindowProxy</span> <span title="dom-iframe-contentWindow">contentWindow</span>;
};</pre>
</dd>
</dl>
<!-- v2 doc="" idea (awaiting implementation experience with seamless="" first):
http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2008-May/014874.html
doc="" would take a string which would then be interpreted as
the source document markup of an HTML document, much like the
above; it would override src="" if it was present, allowing
src="" to be used for legacy UAs:
<iframe seamless sandbox="allow-scripts allow-forms" doc="
<!DOCTYPE HTML>
<title></title>
Welcome to my blog!
</sandbox>
<a href='#' onclick='alert(document.cookie)'>Click here</a>
"></iframe>
(There are things we can do to make this better, e.g. make the
<!DOCTYPE HMTL> and <title></title> bits implicit, maybe
introducing type="" to say whether it's HTML or XML instead of
only supporting HTML, maybe saying that if src="" and doc=""
are both specified they must have identical data, etc.)
-->
<p>The <code>iframe</code> element <span>represents</span> a
<span>nested browsing context</span>.</p>
<p>The <dfn title="attr-iframe-src"><code>src</code></dfn> attribute
gives the address of a page that the <span>nested browsing
context</span> is to contain. The attribute, if present, must be a
<span>valid URL</span>. <span class="impl">When the browsing context
is created, if the attribute is present, the user agent must <span
title="resolve a url">resolve</span> the value of that attribute,
relative to the element, and if that is successful, must then
<span>navigate</span> the element's browsing context to the
resulting <span>absolute URL</span>, with <span>replacement
enabled</span>, and with the <code>iframe</code> element's
document's <span>browsing context</span> as the <span>source
browsing context</span>. If the user <span
title="navigate">navigates</span> away from this page, the
<code>iframe</code>'s corresponding <code>WindowProxy</code> object
will proxy new <code>Window</code> objects for new
<code>Document</code> objects, but the <code
title="attr-iframe-src">src</code> attribute will not
change.</span></p>
<div class="impl">
<p>Whenever the <code title="attr-iframe-src">src</code> attribute
is set, the user agent must <span title="resolve a
url">resolve</span> the value of that attribute, relative to the
element, and if that is successful, the nested <span>browsing
context</span> must be <span title="navigate">navigated</span> to
the resulting <span>absolute URL</span>, with the
<code>iframe</code> element's document's <span>browsing
context</span> as the <span>source browsing context</span>.</p> <!--
It doesn't happen when the base URL is changed, though. -->
<p>If the <code title="attr-iframe-src">src</code> attribute is not
set when the element is created, or if its value cannot be <span
title="resolve a url">resolved</span>, the browsing context will
remain at the initial <code>about:blank</code> page.</p>
</div>
<p>The <dfn title="attr-iframe-name"><code>name</code></dfn>
attribute, if present, must be a <span>valid browsing context
name</span>. The given value is used to name the <span>nested
browsing context</span>. <span class="impl">When the browsing
context is created, if the attribute is present, the <span>browsing
context name</span> must be set to the value of this attribute;
otherwise, the <span>browsing context name</span> must be set to the
empty string.</span></p>
<div class="impl">
<p>Whenever the <code title="attr-iframe-name">name</code> attribute
is set, the nested <span>browsing context</span>'s <span
title="browsing context name">name</span> must be changed to the new
value. If the attribute is removed, the <span>browsing context
name</span> must be set to the empty string.</p>
<p>When content loads in an <code>iframe</code>, after any <code
title="event-load">load</code> events are fired within the content
itself, the user agent must <span>queue a task</span> to <span>fire
a simple event</span> named <code title="event-load">load</code> at
the <code>iframe</code> element. When content fails to load
(e.g. due to a network error), then the user agent must <span>queue
a task</span> to <span>fire a simple event</span> named <code
title="event-error">error</code> at the element instead.</p>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <span>DOM manipulation
task source</span>.</p>
<p>When there is an <span>active parser</span> in the
<code>iframe</code>, and when anything in the <code>iframe</code> is
<span title="delay the load event">delaying the load event</span> of
the <code>iframe</code>'s <span>browsing context</span>'s
<span>active document</span>, the <code>iframe</code> must
<span>delay the load event</span> of its document.</p>
<p class="note">If, during the handling of the <code
title="event-load">load</code> event, the <span>browsing
context</span> in the <code>iframe</code> is again <span
title="navigate">navigated</span>, that will further <span>delay the
load event</span>.</p>
</div>
<hr>
<p>The <dfn title="attr-iframe-sandbox"><code>sandbox</code></dfn>
attribute, when specified, enables a set of extra restrictions on
any content hosted by the <code>iframe</code>. Its value must be an
<span>unordered set of unique space-separated tokens</span>. The
allowed values are <code
title="attr-iframe-sandbox-allow-same-origin">allow-same-origin</code>,
<code title="attr-iframe-sandbox-allow-forms">allow-forms</code>,
and <code
title="attr-iframe-sandbox-allow-scripts">allow-scripts</code>. When
the attribute is set, the content is treated as being from a unique
<span>origin</span>, forms and scripts are disabled, links are
prevented from targeting other <span title="browsing
context">browsing contexts</span>, and plugins are disabled. The
<code
title="attr-iframe-sandbox-allow-same-origin">allow-same-origin</code>
token allows the content to be treated as being from the same origin
instead of forcing it into a unique origin, and the <code
title="attr-iframe-sandbox-allow-forms">allow-forms</code> and <code
title="attr-iframe-sandbox-allow-scripts">allow-scripts</code>
tokens re-enable forms and scripts respectively (though scripts are
still prevented from creating popups).</p>
<div class="impl">
<!-- v2: Add a new attribute that enables new restrictions, e.g.:
- disallow cross-origin loads of any kind (networking
override that only allows same-origin URLs or about:,
javascript:, data:)
- block access to 'parent.frames' from sandbox
-->
<p>While the <code title="attr-iframe-sandbox">sandbox</code>
attribute is specified, the <code>iframe</code> element's
<span>nested browsing context</span>, and all the browsing contexts
<span title="nested browsing context">nested</span> within it
(either directly or indirectly through other nested browsing
contexts) must have the following flags set:</p>
<dl>
<dt>The <dfn>sandboxed navigation browsing context flag</dfn></dt>
<dd>
<p>This flag <a href="#sandboxLinks">prevents content from
navigating browsing contexts other than the sandboxed browsing
context itself</a> (or browsing contexts further nested inside
it).</p>
<p>This flag also <a href="#sandboxWindowOpen">prevents content
from creating new auxiliary browsing contexts</a>, e.g. using the
<code title="attr-hyperlink-target">target</code> attribute or the
<code title="dom-open">window.open()</code> method.</p>
</dd>
<dt>The <dfn>sandboxed plugins browsing context flag</dfn></dt>
<dd>
<p>This flag prevents content from instantiating <span
title="plugin">plugins</span>, whether using <a
href="#sandboxPluginEmbed">the <code>embed</code> element</a>, <a
href="#sandboxPluginObject">the <code>object</code> element</a>,
<a href="#sandboxPluginApplet">the <code>applet</code>
element</a>, or through <a
href="#sandboxPluginNavigate">navigation</a> of a <span>nested
browsing context</span>.</p>
</dd>
<dt>The <dfn>sandboxed seamless iframes flag</dfn></dt>
<dd>
<p>This flag prevents content from using the <code
title="attr-iframe-seamless">seamless</code> attribute on
descendant <code>iframe</code> elements.</p>
<p class="note">This prevents a page inserted using the <code
title="attr-iframe-sandbox-allow-same-origin">allow-same-origin</code>
keyword from using a CSS-selector-based method of probing the DOM
of other pages on the same site (in particular, pages that contain
user-sensitive information).</p>
<!-- http://lists.w3.org/Archives/Public/public-web-security/2009Dec/thread.html#msg51 -->
</dd>
<dt>The <dfn>sandboxed origin browsing context flag</dfn>, unless
the <code title="attr-iframe-sandbox">sandbox</code> attribute's
value, when <span title="split a string on spaces">split on
spaces</span>, is found to have the <dfn
title="attr-iframe-sandbox-allow-same-origin"><code>allow-same-origin</code></dfn>
keyword set</dt>
<dd>
<p>This flag <a href="#sandboxOrigin">forces content into a unique
origin</a> for the purposes of the <span
title="origin">same-origin policy</span>.</p>
<p>This flag also <a href="#sandboxCookies">prevents script from
reading the <code
title="dom-document-cookie">document.cookie</code> IDL
attribute</a>.</p>
<div class="note">
<p>The <code
title="attr-iframe-sandbox-allow-same-origin">allow-same-origin</code>
attribute is intended for two cases.</p>
<p>First, it can be used to allow content from the same site to
be sandboxed to disable scripting, while still allowing access to
the DOM of the sandboxed content.</p>
<p>Second, it can be used to embed content from a third-party
site, sandboxed to prevent that site from opening popup windows,
etc, without preventing the embedded page from communicating back
to its originating site, using the database APIs to store data,
etc.</p>
</div>
<p class="warning">This flag only takes effect when the
<span>nested browsing context</span> of the <code>iframe</code> is
<span title="navigate">navigated</span>.</p>
</dd>
<dt>The <dfn>sandboxed forms browsing context flag</dfn>, unless
the <code title="attr-iframe-sandbox">sandbox</code> attribute's
value, when <span title="split a string on spaces">split on
spaces</span>, is found to have the <dfn
title="attr-iframe-sandbox-allow-forms"><code>allow-forms</code></dfn>
keyword set</dt>
<dd>
<p>This flag <a href="#sandboxSubmitBlocked">blocks form
submission</a>.</p>
</dd>
<dt>The <dfn>sandboxed scripts browsing context flag</dfn>, unless
the <code title="attr-iframe-sandbox">sandbox</code> attribute's
value, when <span title="split a string on spaces">split on
spaces</span>, is found to have the <dfn
title="attr-iframe-sandbox-allow-scripts"><code>allow-scripts</code></dfn>
keyword set</dt>
<dd>
<p>This flag <a href="#sandboxScriptBlocked">blocks script
execution</a>.</p>
<p class="warning">If the <code
title="attr-iframe-sandbox">sandbox</code> attribute is
dynamically added after the <code>iframe</code> has loaded a page,
scripts already compiled by that page (whether in
<code>script</code> elements, or in <span>event handlers</span>,
or elsewhere) will continue to run. Only <em>new</em> scripts will
be prevented from executing by this flag.</p>
</dd>
</dl>
<p>These flags must not be set unless the conditions listed above
define them as being set.</p>
</div>
<div class="example">
<p>In this example, some completely-unknown, potentially hostile,
user-provided HTML content is embedded in a page. Because it is
sandboxed, it is treated by the user agent as being from a unique
origin, despite the content being served from the same site. Thus
it is affected by all the normal cross-site restrictions. In
addition, the embedded page has scripting disabled, plugins
disabled, forms disabled, and it cannot navigate any frames or
windows other than itself (or any frames or windows it itself
embeds).</p>
<pre><p>We're not scared of you! Here is your content, unedited:</p>
<iframe sandbox src="getusercontent.cgi?id=12193"></iframe></pre>
<p>Note that cookies are still sent to the server in the <code
title="">getusercontent.cgi</code> request, though they are not
visible in the <code
title="dom-document-cookie">document.cookie</code> IDL
attribute.</p>
</div>
<div class="example">
<p>In this example, a gadget from another site is embedded. The
gadget has scripting and forms enabled, and the origin sandbox
restrictions are lifted, allowing the gadget to communicate with
its originating server. The sandbox is still useful, however, as it
disables plugins and popups, thus reducing the risk of the user
being exposed to malware and other annoyances.</p>
<pre><iframe sandbox="allow-same-origin allow-forms allow-scripts"
src="http://maps.example.com/embedded.html"></iframe></pre>
</div>
<hr>
<!-- v2: Might be interesting to have a value on seamless that
allowed event propagation of some sort, maybe based on the WICD
work: http://www.w3.org/TR/WICD/ -->
<p>The <dfn title="attr-iframe-seamless"><code>seamless</code></dfn>
attribute is a <span>boolean attribute</span>. When specified, it
indicates that the <code>iframe</code> element's <span>browsing
context</span> is to be rendered in a manner that makes it appear to
be part of the containing document (seamlessly included in the
parent document). <span class="impl">Specifically, when the
attribute is set on an <code>iframe</code> element whose owner
<code>Document</code>'s <span>browsing context</span> does not have
the <span>sandboxed seamless iframes flag</span> set and while
either the <span>browsing context</span>'s <span>active
document</span> has the <span>same origin</span> as the
<code>iframe</code> element's document, or the <span>browsing
context</span>'s <span>active document</span>'s <em><span title="the
document's address">address</span></em> has the <span>same
origin</span> as the <code>iframe</code> element's document, the
following requirements apply:</span></p>
<div class="impl">
<ul>
<li><p>The user agent must set the <dfn>seamless browsing
context flag</dfn> to true for that <span>browsing
context</span>. This will <a href="#seamlessLinks">cause links to
open in the parent browsing context</a>.</p></li>
<li><p>In a CSS-supporting user agent: the user agent must add all
the style sheets that apply to the <code>iframe</code> element to
the cascade of the <span>active document</span> of the
<code>iframe</code> element's <span>nested browsing context</span>,
at the appropriate cascade levels, before any style sheets
specified by the document itself.</p></li>
<li><p>In a CSS-supporting user agent: the user agent must, for the
purpose of CSS property inheritance only, treat the root element of
the <span>active document</span> of the <code>iframe</code>
element's <span>nested browsing context</span> as being a child of
the <code>iframe</code> element. (Thus inherited properties on the
root element of the document in the <code>iframe</code> will
inherit the computed values of those properties on the
<code>iframe</code> element instead of taking their initial
values.)</p></li>
<li><p>In visual media, in a CSS-supporting user agent: the user agent
should set the intrinsic width of the <code>iframe</code> to the
width that the element would have if it was a non-replaced
block-level element with 'width: auto'.</p></li>
<li><p>In visual media, in a CSS-supporting user agent: the user
agent should set the intrinsic height of the <code>iframe</code> to
the height of the bounding box around the content rendered in the
<code>iframe</code> at its current width (as given in the previous
bullet point), as it would be if the scrolling position was such
that the top of the viewport for the content rendered in the
<code>iframe</code> was aligned with the origin of that content's
canvas.</p></li>
<li>
<p>In visual media, in a CSS-supporting user agent: the user agent
must force the height of the initial containing block of the
<span>active document</span> of the <span>nested browsing
context</span> of the <code>iframe</code> to zero.</p>
<p class="note">This is intended to get around the otherwise
circular dependency of percentage dimensions that depend on the
height of the containing block, thus affecting the height of the
document's bounding box, thus affecting the height of the
viewport, thus affecting the size of the initial containing
block.</p>
</li>
<li><p>In speech media, the user agent should render the <span>nested
browsing context</span> without announcing that it is a separate
document.</p></li>
<li>
<p>User agents should, in general, act as if the <span>active
document</span> of the <code>iframe</code>'s <span>nested browsing
context</span> was part of the document that the
<code>iframe</code> is in.</p>
<p class="example">For example if the user agent supports listing
all the links in a document, links in "seamlessly" nested
documents would be included in that list without being
significantly distinguished from links in the document itself.</p>
</li>
</ul>
<p>If the attribute is not specified, or if the <span>origin</span>
conditions listed above are not met, then the user agent should
render the <span>nested browsing context</span> in a manner that is
clearly distinguishable as a separate <span>browsing context</span>,
and the <span>seamless browsing context flag</span> must be set to
false for that <span>browsing context</span>.</p>
<p class="warning">It is important that user agents recheck the
above conditions whenever the <span>active document</span> of the
<span>nested browsing context</span> of the <code>iframe</code>
changes, such that the <span>seamless browsing context flag</span>
gets unset if the <span>nested browsing context</span> is <span
title="navigate">navigated</span> to another origin.</p>
</div>
<p class="note">The attribute can be set or removed dynamically,
with the rendering updating in tandem.</p>
<div class="example">
<p>In this example, the site's navigation is embedded using a
client-side include using an <code>iframe</code>. Any links in the
<code>iframe</code> will, in new user agents, be automatically
opened in the <code>iframe</code>'s parent browsing context; for
legacy user agents, the site could also include a <code>base</code>
element with a <code title="attr-base-target">target</code>
attribute with the value <code title="">_parent</code>. Similarly,
in new user agents the styles of the parent page will be
automatically applied to the contents of the frame, but to support
legacy user agents authors might wish to include the styles
explicitly.</p>
<pre><nav><iframe seamless src="nav.include.html"></iframe></nav></pre>
</div>
<hr>
<p>The <code>iframe</code> element supports <span>dimension
attributes</span> for cases where the embedded content has specific
dimensions (e.g. ad units have well-defined dimensions).</p>
<p>An <code>iframe</code> element never has <span>fallback
content</span>, as it will always create a nested <span>browsing
context</span>, regardless of whether the specified initial contents
are successfully used.</p>
<p>Descendants of <code>iframe</code> elements represent
nothing. (In legacy user agents that do not support
<code>iframe</code> elements, the contents would be parsed as markup
that could act as fallback content.)</p>
<p>When used in <span>HTML documents</span>, the allowed content
model of <code>iframe</code> elements is text, except that invoking
the <span>HTML fragment parsing algorithm</span> with the
<code>iframe</code> element as the <var title="">context</var>
element and the text contents as the <var title="">input</var> must
result in a list of nodes that are all <span>phrasing
content</span>, with no <span title="parse error">parse
errors</span> having occurred, with no <code>script</code> elements
being anywhere in the list or as descendants of elements in the
list, and with all the elements in the list (including their
descendants) being themselves conforming.</p>
<p>The <code>iframe</code> element must be empty in <span>XML
documents</span>.</p>
<p class="note">The <span>HTML parser</span> treats markup inside
<code>iframe</code> elements as text.</p>
<div class="impl">
<p>The IDL attributes <dfn
title="dom-iframe-src"><code>src</code></dfn>, <dfn
title="dom-iframe-name"><code>name</code></dfn>, <dfn
title="dom-iframe-sandbox"><code>sandbox</code></dfn>, and <dfn
title="dom-iframe-seamless"><code>seamless</code></dfn> must
<span>reflect</span> the respective content attributes of the same
name.</p>
<p>The <dfn
title="dom-iframe-contentDocument"><code>contentDocument</code></dfn>
IDL attribute must return the <code>Document</code> object of the
<span>active document</span> of the <code>iframe</code> element's
<span>nested browsing context</span>.</p>
<p>The <dfn
title="dom-iframe-contentWindow"><code>contentWindow</code></dfn>
IDL attribute must return the <code>WindowProxy</code> object of the
<code>iframe</code> element's <span>nested browsing
context</span>.</p>
</div>
<div class="example">
<p>Here is an example of a page using an <code>iframe</code> to
include advertising from an advertising broker:</p>
<pre><iframe src="http://ads.example.com/?customerid=923513721&amp;format=banner"
width="468" height="60"></iframe></pre>
</div>
<h4>The <dfn><code>embed</code></dfn> element</h4>
<!-- (v2?)
we have all kinds of quirks we should define if they come up during
testing, as e.g. shown in:
http://mxr.mozilla.org/mozilla-central/source/layout/generic/nsObjectFrame.cpp
http://trac.webkit.org/browser/trunk/WebCore/html/HTMLEmbedElement.cpp
http://trac.webkit.org/browser/trunk/WebCore/rendering/RenderPartObject.cpp (updateWidget)
e.g. - 240x200 default
- the attributes/params are sent in a name/value pair list as follows (for Gecko):
+ attributes of the element, in source order
+ a synthesised 'src' attribute, if there was no 'src' but
there was a 'data', with the value of the 'data' attribute
+ PARAM/null
+ the params, in source order
(WebKit does something different still)
- the HIDDEN attribute (might be moot now)
-->
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Embedded content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>embedded content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-embed-src">src</code></dd>
<dd><code title="attr-embed-type">type</code></dd>
<dd><code title="attr-dim-width">width</code></dd>
<dd><code title="attr-dim-height">height</code></dd>
<dd>Any other attribute that has no namespace (see prose).</dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLEmbedElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-embed-src">src</span>;
attribute DOMString <span title="dom-embed-type">type</span>;
attribute DOMString <span title="dom-dim-width">width</span>;
attribute DOMString <span title="dom-dim-height">height</span>;
};</pre>
<div class="impl">
<p>Depending on the type of content instantiated by the
<code>embed</code> element, the node may also support other
interfaces.</p>
</div>
</dd>
</dl>
<p>The <code>embed</code> element <span>represents</span> an
integration point for an external (typically non-HTML) application
or interactive content.</p>
<p>The <dfn title="attr-embed-src"><code>src</code></dfn> attribute
gives the address of the resource being embedded. The attribute, if
present, must contain a <span>valid URL</span>.</p>
<p>The <dfn title="attr-embed-type"><code>type</code></dfn>
attribute, if present, gives the <span>MIME type</span> of the plugin to
instantiate. The value must be a <span>valid MIME type</span>,
optionally with parameters. If both the <code
title="attr-embed-type">type</code> attribute and the <code
title="attr-embed-src">src</code> attribute are present, then the
<code title="attr-embed-type">type</code> attribute must specify the
same type as the <span title="Content-Type">explicit Content-Type
metadata</span> of the resource given by the <code
title="attr-embed-src">src</code> attribute.</p>
<div class="impl">
<p>When the element is created with neither a <code
title="attr-embed-src">src</code> attribute nor a <code
title="attr-embed-type">type</code> attribute, and when attributes
are removed such that neither attribute is present on the element
anymore, and when the element has a <span>media element</span>
ancestor, and when the element has an ancestor <code>object</code>
element that is <em>not</em> showing its <span>fallback
content</span>, any plugins instantiated for the element must be
removed, and the <code>embed</code> element represents nothing.</p>
<p id="sandboxPluginEmbed">When the <span>sandboxed plugins browsing
context flag</span> is set on the <span>browsing context</span> for
which the <code>embed</code> element's document is the <span>active
document</span>, then the user agent must render the
<code>embed</code> element in a manner that conveys that the
<span>plugin</span> was disabled. The user agent may offer the user
the option to override the sandbox and instantiate the
<span>plugin</span> anyway; if the user invokes such an option, the
user agent must act as if the <span>sandboxed plugins browsing
context flag</span> was not set for the purposes of this
element.</p>
<p class="warning">Plugins are disabled in sandboxed browsing
contexts because they might not honor the restrictions imposed by
the sandbox (e.g. they might allow scripting even when scripting in
the sandbox is disabled). User agents should convey the danger of
overriding the sandbox to the user if an option to do so is
provided.</p>
<p>An <code>embed</code> element is said to be <dfn
title="concept-embed-active">potentially active</dfn> when the
following conditions are all met simultaneously:</p>
<ul class="brief">
<li>The element is <span title="in a document">in a <code>Document</code></span>.</li>
<li>The element's <code>Document</code> is <span>fully active</span>.</li>
<li>The element has either a <code title="attr-embed-src">src</code> attribute set or a <code title="attr-embed-type">type</code> attribute set (or both).</li>
<li>The element is not in a sandboxed browsing context.</li>
<li>The element is not a descendant of a <span>media element</span>.</li>
<li>The element is not a descendant of an <code>object</code> element that is not showing its <span>fallback content</span>.</li>
</ul>
<p>Whenever an <code>embed</code> element that was not <span
title="concept-embed-active">potentially active</span> becomes <span
title="concept-embed-active">potentially active</span>, and whenever
a <span title="concept-embed-active">potentially active</span>
<code>embed</code> element's <code
title="attr-embed-type">src</code> attribute is set, changed, or
removed, and whenever a <span
title="concept-embed-active">potentially active</span>
<code>embed</code> element's <code
title="attr-embed-type">type</code> attribute is set, changed, or
removed, the appropriate set of steps from the following is then
applied:</p>
<dl class="switch">
<dt>If the element has a <code title="attr-embed-src">src</code>
attribute set</dt>
<dd>
<p>The user agent must <span title="resolve a url">resolve</span>
the value of the element's <code title="attr-embed-src">src</code>
attribute, relative to the element. If that is successful, the
user agent should <span>fetch</span> the resulting <span>absolute
URL</span>, from the element's <span>browsing context scope
origin</span> if it has one<!-- potentially http-origin privacy
sensitive -->. The <span title="concept-task">task</span> that is
<span title="queue a task">queued</span> by the <span>networking
task source</span> once the resource has been <span
title="fetch">fetched</span> must find and instantiate an
appropriate <span>plugin</span> based on the <span
title="concept-embed-type">content's type</span>, and hand that
<span>plugin</span> the content of the resource, replacing any
previously instantiated plugin for the element.</p> <!-- Note that
this doesn't happen when the base URL changes. -->
<p>Fetching the resource must <span>delay the load event</span> of
the element's document.</p>
<!-- if we add load/error events, then replace the previous
paragraph with the text one: -->
<!-- similar text in various places -->
<!--<p>Fetching the resource must <span>delay the load
event</span> of the element's document until the final <span
title="concept-task">task</span> that is <span title="queue a
task">queued</span> by the <span>networking task source</span>
once the resource has been <span title="fetch">fetched</span> has
been run.</p>-->
</dd>
<dt>If the element has no <code title="attr-embed-src">src</code>
attribute set</dt>
<dd><p>The user agent should find and instantiate an appropriate
<span>plugin</span> based on the value of the <code
title="attr-embed-type">type</code> attribute.</p>
</dl>
<p>Whenever an <code>embed</code> element that was <span
title="concept-embed-active">potentially active</span> stops being
<span title="concept-embed-active">potentially active</span>, any
<span>plugin</span> that had been instantiated for that element must
be unloaded.</p>
<p class="note">The <code>embed</code> element is unaffected by the
CSS 'display' property. The selected plugin is instantiated even if
the element is hidden with a 'display:none' CSS style.</p>
<p>The <dfn title="concept-embed-type">type of the content</dfn>
being embedded is defined as follows:</p>
<ol>
<li><p>If the element has a <code
title="attr-embed-type">type</code> attribute, and that attribute's
value is a type that a <span>plugin</span> supports, then the value
of the <code title="attr-embed-type">type</code> attribute is the
<span title="concept-embed-type">content's type</span>.</p></li>
<li>
<p>Otherwise, if the <span title="url-path"><path></span>
component of the <span>URL</span> of the specified resource (after
any redirects) matches a pattern that a <span>plugin</span>
supports, then the <span title="concept-embed-type">content's
type</span> is the type that that plugin can handle.</p>
<p class="example">For example, a plugin might say that it can
handle resources with <span title="url-path"><path></span>
components that end with the four character string "<code
title="">.swf</code>".</p>
<!-- it's sad that we have to do extension sniffing. sigh. -->
<!-- see also <object> which has a similar step -->
</li>
<li><p>Otherwise, if the specified resource has <span
title="Content-Type">explicit Content-Type metadata</span>, then
that is the <span title="concept-embed-type">content's
type</span>.</p></li>
<li><p>Otherwise, the content has no type and there can be no
appropriate <span>plugin</span> for it.</p></li>
<!-- This algorithm is a monument to bad design. Go legacy! -->
</ol>
<p>The <code>embed</code> element has no <span>fallback
content</span>. If the user agent can't find a suitable plugin, then
the user agent must use a default plugin. (This default could be as
simple as saying "Unsupported Format".)</p>
<p>Whether the resource is fetched successfully or not (e.g. whether
the response code was a 2xx code <span
title="concept-http-equivalent-codes">or equivalent</span>) must be
ignored when determining the resource's type and when handing the
resource to the plugin.</p>
<p class="note">This allows servers to return data for plugins even
with error responses (e.g. HTTP 500 Internal Server Error codes can
still contain plugin data).</p>
</div>
<p>Any namespace-less attribute other than <code
title="attr-embed-name">name</code> and <code
title="attr-embed-align">align</code> <!-- when editing, see also
note below --> may be specified on the <code>embed</code> element,
so long as its name is <span>XML-compatible</span> and contains no
characters in the range U+0041 to U+005A (LATIN CAPITAL LETTER A to
LATIN CAPITAL LETTER Z). These attributes are then passed as
parameters to the <span>plugin</span>.</p>
<p class="note">All attributes in <span>HTML documents</span> get
lowercased automatically, so the restriction on uppercase letters
doesn't affect such documents.</p>
<p class="note">The two exceptions are to exclude legacy attributes
that have side-effects beyond just sending parameters to the
<span>plugin</span>.</p>
<div class="impl">
<p>The user agent should pass the names and values of all the
attributes of the <code>embed</code> element that have no namespace
to the <span>plugin</span> used, when it is instantiated.</p>
<p>If the <span>plugin</span> instantiated for the
<code>embed</code> element supports a scriptable interface, the
<code>HTMLEmbedElement</code> object representing the element should
expose that interface while the element is instantiated.</p>
</div>
<p>The <code>embed</code> element supports <span>dimension
attributes</span>.</p>
<div class="impl">
<p>The IDL attributes <dfn
title="dom-embed-src"><code>src</code></dfn> and <dfn
title="dom-embed-type"><code>type</code></dfn> each must
<span>reflect</span> the respective content attributes of the same
name.</p>
</div>
<div class="example">
<p>Here's a way to embed a resource that requires a proprietary
plug-in, like Flash:</p>
<pre><embed src="catgame.swf"></pre>
<p>If the user does not have the plug-in (for example if the
plug-in vendor doesn't support the user's platform), then the user
will be unable to use the resource.</p>
<p>To pass the plugin a parameter "quality" with the value "high",
an attribute can be specified:</p>
<pre><embed src="catgame.swf" quality="high"></pre>
<p>This would be equivalent to the following, when using an
<code>object</code> element instead:</p>
<pre><object data="catgame.swf">
<param name="quality" value="high">
</object></pre>
</div>
<h4>The <dfn><code>object</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Embedded content</span>.</dd>
<dd>If the element has a <code title="attr-hyperlink-usemap">usemap</code> attribute: <span>Interactive content</span>.</dd> <!-- also when showing a plugin or a nested browsing context, but checking that statically is hard...) -->
<dd><span title="category-listed">Listed</span>, <span title="category-submit">submittable</span>, <span>form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>embedded content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>param</code> elements, then, <span>transparent</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-object-data">data</code></dd>
<dd><code title="attr-object-type">type</code></dd>
<dd><code title="attr-object-name">name</code></dd>
<dd><code title="attr-hyperlink-usemap">usemap</code></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-dim-width">width</code></dd>
<dd><code title="attr-dim-height">height</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLObjectElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-object-data">data</span>;
attribute DOMString <span title="dom-object-type">type</span>;
attribute DOMString <span title="dom-object-name">name</span>;
attribute DOMString <span title="dom-object-useMap">useMap</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
attribute DOMString <span title="dom-dim-width">width</span>;
attribute DOMString <span title="dom-dim-height">height</span>;
readonly attribute Document <span title="dom-object-contentDocument">contentDocument</span>;
readonly attribute <span>WindowProxy</span> <span title="dom-object-contentWindow">contentWindow</span>;
readonly attribute boolean <span title="dom-cva-willValidate">willValidate</span>;
readonly attribute <span>ValidityState</span> <span title="dom-cva-validity">validity</span>;
readonly attribute DOMString <span title="dom-cva-validationMessage">validationMessage</span>;
boolean <span title="dom-cva-checkValidatity">checkValidity</span>();
void <span title="dom-cva-setCustomValidity">setCustomValidity</span>(in DOMString error);
};</pre>
<div class="impl">
<p>Depending on the type of content instantiated by the
<code>object</code> element, the node also supports other
interfaces.</p>
</div>
</dd>
</dl>
<p>The <code>object</code> element can represent an external
resource, which, depending on the type of the resource, will either
be treated as an image, as a <span>nested browsing context</span>,
or as an external resource to be processed by a
<span>plugin</span>.</p>
<p>The <dfn title="attr-object-data"><code>data</code></dfn>
attribute, if present, specifies the address of the resource. If
present, the attribute must be a <span>valid URL</span>.</p>
<p>The <dfn title="attr-object-type"><code>type</code></dfn>
attribute, if present, specifies the type of the resource. If
present, the attribute must be a <span>valid MIME type</span>,
optionally with parameters.</p>
<p>One or both of the <code title="attr-object-data">data</code> and
<code title="attr-object-type">type</code> attributes must be
present.</p>
<p>The <dfn title="attr-object-name"><code>name</code></dfn>
attribute, if present, must be a <span>valid browsing context
name</span>. The given value is used to name the <span>nested
browsing context</span>, if applicable.</p>
<div class="impl">
<p>When the element is created, and subsequently whenever the
element is <span title="insert an element into a document">inserted
into a document</span> or <span title="remove an element from a
document">removed from a document</span>; and whenever the element's
<code>Document</code> changes whether it is <span>fully
active</span>; and whenever an ancestor <code>object</code> element
changes to or from showing its <span>fallback content</span>; and
whenever the element's <code
title="attr-object-classid">classid</code> attribute is set,
changed, or removed; and, when its <code
title="attr-object-classid">classid</code> attribute is not present,
whenever its <code title="attr-object-data">data</code> attribute is
set, changed, or removed; and, when neither its <code
title="attr-object-classid">classid</code> attribute nor its <code
title="attr-object-data">data</code> attribute are present, whenever
its <code title="attr-object-type">type</code> attribute is set,
changed, or removed: the user agent must <span>queue a task</span>
to run the following steps to (re)determine what the
<code>object</code> element represents:</p>
<!-- Changing the base URL doesn't trigger this. -->
<ol>
<li>
<p>If the element has an ancestor <span>media element</span>, or
has an ancestor <code>object</code> element that is <em>not</em>
showing its <span>fallback content</span>, or if the element is
not <span title="in a document">in a <code>Document</code></span>,
or if the element's <code>Document</code> is not <span>fully
active</span>, then jump to the last step in the overall set of
steps (fallback).</p>
</li>
<li>
<p>If the <code title="attr-object-classid">classid</code>
attribute is present, and has a value that isn't the empty string,
then: if the user agent can find a <span>plugin</span> suitable
according to the value of the <code
title="attr-object-classid">classid</code> attribute, and <a
href="#sandboxPluginObject">plugins aren't being sandboxed</a>,
then that <span>plugin</span> <a href="#object-plugin">should be
used</a>, and the value of the <code
title="attr-object-data">data</code> attribute, if any, should be
passed to the <span>plugin</span>. If no suitable
<span>plugin</span> can be found, or if the <span>plugin</span>
reports an error, jump to the last step in the overall set of
steps (fallback).</p>
<!--
case insensitive:
is "clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" -> application/x-shockwave-flash
is "clsid:cfcdaa03-8be4-11cf-b84b-0020afbbccfa" -> audio/x-pn-realaudio-plugin
is "clsid:02bf25d5-8c17-4b23-bc80-d3488abddc6b" -> video/quicktime
is "clsid:166b1bca-3f9c-11cf-8075-444553540000" -> application/x-director
is "clsid:6bf52a52-394a-11d3-b153-00c04f79faa6" -> application/x-mplayer2
starts with "java:" -> application/x-java-vm
starts with "clsid:" -> application/x-oleobject
-->
</li>
<!-- (v2?)
we may have to define magic fallback to <param> if it turns out to
be needed in testing:
<hyatt> apparently your url can come from <param>
<hyatt> not just the data attribute
<hyatt> our code looks for params with "src", "movie", "code" and "url"
<hyatt> and also tries to find the type on a param
<Hixie> oh that's you trying to have hacky activex support
<Hixie> opera does that too
<hyatt> yeah we support activex versions of plugins that are common
<hyatt> like flash and quicktime and realaudio
<Hixie> that would be a step 1b. if no data attribute, then look for a <param> to get you a URL instead.
<Hixie> and if you find one, carry on as if that was your data="".
-->
<li><p>If the <code title="attr-object-data">data</code> attribute
is present, then:</p>
<ol>
<li><p>If the <code title="attr-object-type">type</code>
attribute is present and its value is not a type that the user
agent supports, and is not a type that the user agent can find a
<span>plugin</span> for, then the user agent may jump to the last
step in the overall set of steps (fallback) without fetching the
content to examine its real type.</p></li>
<li>
<p><span title="resolve a url">Resolve</span> the
<span>URL</span> specified by the <code
title="attr-object-data">data</code> attribute, relative to the
element.</p>
<p>If that is successful, <span>fetch</span> the resulting
<span>absolute URL</span>, from the element's <span>browsing
context scope origin</span> if it has one<!-- potentially
http-origin privacy sensitive -->.</p>
<!-- similar text in various places -->
<p>Fetching the resource must <span>delay the load event</span>
of the element's document until the <span
title="concept-task">task</span> that is <span title="queue a
task">queued</span> by the <span>networking task source</span>
once the resource has been <span title="fetch">fetched</span>
(defined next) has been run.</p>
</li>
<li><p>If the resource is not yet available (e.g. because the
resource was not available in the cache, so that loading the
resource required making a request over the network), then jump
to the last step in the overall set of steps (fallback). The
<span title="concept-task">task</span> that is <span title="queue
a task">queued</span> by the <span>networking task source</span>
once the resource is available must restart this algorithm from
this step. Resources can load incrementally; user agents may opt
to consider a resource "available" whenever enough data has been
obtained to begin processing the resource.</p></li>
<li><p>If the load failed (e.g. the <span>URL</span> could not be
<span title="resolve a url">resolved</span>, there was an HTTP
404 error, there was a DNS error), <span>fire a simple
event</span> named <code title="event-error">error</code> at the
element, then jump to the last step in the overall set of steps
(fallback).</p></li>
<li><p>Determine the <var title="">resource type</var>, as follows:</p>
<ol>
<li>
<p>Let the <var title="">resource type</var> be unknown.</p>
</li>
<li>
<p>Let the <var title="">sniffed</var> flag be false.</p>
</li>
<li>
<p>If there is a <code title="attr-object-type">type</code>
attribute present on the <code>object</code> element, and that
attribute's value is not a type that the user agent supports,
but it <em>is</em> a type that a <span>plugin</span> supports,
then let the <var title="">resource type</var> be the type
specified in that <code title="attr-object-type">type</code>
attribute.</p>
</li>
<li>
<p>Otherwise, if the <var title="">resource type</var> is
unknown, and the resource has <span
title="Content-Type">associated Content-Type metadata</span>,
then let the <var title="">resource type</var> be the type
specified in <span title="Content-Type">the resource's
Content-Type metadata</span>.</p>
<p>If this results in thee <var title="">resource type</var>
being "<code title="">text/plain</code>", then let the <var
title="">resource type</var> be the result of applying the
<span title="Content-Type sniffing: text or binary">rules for
distingushing if a resource is text or binary</span> to the
resource instead, and then set the <var title="">sniffed</var>
flag to true.</p>
</li>
<li>
<p>If the <var title="">resource type</var> is unknown or
"<code title="">application/octet-stream</code>" at this point
and there is a <code title="attr-object-type">type</code>
attribute present on the <code>object</code> element, then
change the <var title="">resource type</var> to instead be the
type specified in that <code
title="attr-object-type">type</code> attribute.</p>
<p>Otherwise, if the <var title="">resource type</var> is
"<code title="">application/octet-stream</code>" but there is
no <code title="attr-object-type">type</code> attribute on the
<code>object</code> element, then change the <var
title="">resource type</var> to be unknown, so that the
sniffing rules in the following steps are invoked.</p>
</li>
<li>
<p>If the <var title="">resource type</var> is still unknown
at this point, but the <span
title="url-path"><path></span> component of the
<span>URL</span> of the specified resource (after any
redirects) matches a pattern that a <span>plugin</span>
supports, then let <var title="">resource type</var> be the
type that that plugin can handle.</p>
<p class="example">For example, a plugin might say that it can
handle resources with <span title="url-path"><path></span>
components that end with the four character string "<code
title="">.swf</code>".</p>
<!-- it's sad that we have to do extension sniffing. sigh. -->
<!-- see also <embed> which has a similar step -->
</li>
<li>
<p>If the <var title="">resource type</var> is still unknown,
and the <var title="">sniffed</var> flag is false, then change
the <var title="">resource type</var> to instead be the <span
title="content-type sniffing">sniffed type of the
resource</span>.</p>
<p>Otherwise, if the <var title="">resource type</var> is
still unknown, and the <var title="">sniffed</var> flag is
<em>true</em>, then change the <var title="">resource
type</var> back to <code title="">text/plain</code>.</p>
</li>
</ol>
</li>
<li><p>Handle the content as given by the first of the following
cases that matches:</p>
<dl class="switch">
<dt>If the <var title="">resource type</var> is not a type that
the user agent supports, but it <em>is</em> a type that a
<span>plugin</span> supports</dt>
<dd>
<p>If <a href="#sandboxPluginObject">plugins are being
sandboxed</a>, jump to the last step in the overall set of
steps (fallback).</p>
<p>Otherwise, the user agent should <a
href="#object-plugin">use the plugin that supports <var
title="">resource type</var></a> and pass the content of the
resource to that <span>plugin</span>. If the
<span>plugin</span> reports an error, then jump to the last
step in the overall set of steps (fallback).</p>
</dd>
<dt>If the <var title="">resource type</var> is an <span>XML MIME
type</span>, or
<!-- (redundant with the next one) if the <var title="">resource type</var> is HTML, or -->
if the <var title="">resource type</var> does not start with
"<code>image/</code>"</dt>
<dd>
<p>The <code>object</code> element must be associated with a
<span>nested browsing context</span>, if it does not already
have one. The element's <span>nested browsing context</span>
must then be <span title="navigate">navigated</span> to the
given resource, with <span>replacement enabled</span>, and
with the <code>object</code> element's document's
<span>browsing context</span> as the <span>source browsing
context</span>. (The <code
title="attr-object-data">data</code> attribute of the
<code>object</code> element doesn't get updated if the
browsing context gets further navigated to other
locations.)</p>
<p>The <code>object</code> element <span>represents</span> the
<span>nested browsing context</span>.</p>
<p>If the <code title="attr-object-name">name</code> attribute
is present, the <span>browsing context name</span> must be set
to the value of this attribute; otherwise, the <span>browsing
context name</span> must be set to the empty string.</p>
<p class="note">It's possible that the <span
title="navigate">navigation</span> of the <span>browsing
context</span> will actually obtain the resource from a
different <span>application cache</span>. Even if the resource
is then found to have a different type, it is still used as
part of a <span>nested browsing context</span>; this algorithm
doesn't restart with the new resource.</p>
<!-- note that malformed XML files don't cause fallback -->
</dd>
<dt>If the <var title="">resource type</var> starts with
"<code>image/</code>", and support for images has not been
disabled</dt>
<dd>
<p>Apply the <span title="content-type sniffing: image">image
sniffing</span> rules to determine the type of the image.</p>
<p>The <code>object</code> element <span>represents</span> the
specified image. The image is not a <span>nested browsing
context</span>.</p>
<p>If the image cannot be rendered, e.g. because it is
malformed or in an unsupported format, jump to the last step
in the overall set of steps (fallback).</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p>The given <var title="">resource type</var> is not
supported. Jump to the last step in the overall set of steps
(fallback).</p>
</dd>
</dl>
</li>
<li><p>The element's contents are not part of what the
<code>object</code> element represents.</p>
<li>
<p>Once the resource is completely loaded, <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-load">load</code> at the element.</p>
<p>The <span>task source</span> for this task<!--tasks mentioned
in this section--> is the <span>DOM manipulation task
source</span>.</p>
</li>
</ol>
</li>
<li><p>If the <code title="attr-object-data">data</code> attribute
is absent but the <code title="attr-object-type">type</code>
attribute is present, <a href="#sandboxPluginObject">plugins
aren't being sandboxed</a>, and the user agent can find a <span>plugin</span>
suitable according to the value of the <code
title="attr-object-type">type</code> attribute, then that <span>plugin</span>
<a href="#object-plugin">should be used</a>. If no suitable <span>plugin</span>
can be found, or if the <span>plugin</span> reports an error, jump to the next
step (fallback).</p></li>
<li><p>(Fallback.) The <code>object</code> element
<span>represents</span> the element's children, ignoring any
leading <code>param</code> element children. This is the element's
<span>fallback content</span>. If the element has an instantiated
<span>plugin</span>, then unload it.</p></li>
</ol>
<p>The <span>task source</span> for the <span
title="concept-task">task</span> above is the <span>DOM manipulation
task source</span>.</p>
<p id="object-plugin">When the algorithm above instantiates a
<span>plugin</span>, the user agent should pass the names and values
of all the attributes on the element, and <!-- then a parameter
named "PARAM" whose value is null, and then --> all the names and
values of <span title="concept-param-parameter">parameters</span>
given by <code>param</code> elements that are children of the
<code>object</code> element, in <span>tree order</span>, to the
<span>plugin</span> used. If the <span>plugin</span> supports a
scriptable interface, the <code>HTMLObjectElement</code> object
representing the element should expose that interface. The
<code>object</code> element <span>represents</span> the
<span>plugin</span>. The <span>plugin</span> is not a nested
<span>browsing context</span>.</p>
<p id="sandboxPluginObject">If the <span>sandboxed plugins browsing
context flag</span> is set on the <span>browsing context</span> for
which the <code>object</code> element's document is the <span>active
document</span>, then the steps above must always act as if they had
failed to find a <span>plugin</span>, even if one would otherwise have been
used.</p>
<p class="note">The above algorithm is independent of CSS properties
(including 'display', 'overflow', and 'visibility'). For example, it
runs even if the element is hidden with a 'display:none' CSS style,
and does not run <em>again</em> if the element's visibility
changes.</p>
<p>Due to the algorithm above, the contents of <code>object</code>
elements act as <span>fallback content</span>, used only when
referenced resources can't be shown (e.g. because it returned a 404
error). This allows multiple <code>object</code> elements to be
nested inside each other, targeting multiple user agents with
different capabilities, with the user agent picking the first one it
supports.</p>
<p>Whenever the <code title="attr-object-name">name</code> attribute
is set, if the <code>object</code> element has a nested
<span>browsing context</span>, its <span title="browsing context
name">name</span> must be changed to the new value. If the attribute
is removed, if the <code>object</code> element has a <span>browsing
context</span>, the <span>browsing context name</span> must be set
to the empty string.</p>
</div>
<p>The <code title="attr-hyperlink-usemap">usemap</code> attribute,
if present while the <code>object</code> element represents an
image, can indicate that the object has an associated <span>image
map</span>. <span class="impl">The attribute must be ignored if the
<code>object</code> element doesn't represent an image.</span></p>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>object</code> element with its
<span>form owner</span>.</p>
<div class="impl">
<p><strong>Constraint validation</strong>: <code>object</code>
elements are always <span>barred from constraint
validation</span>.</p>
</div>
<p>The <code>object</code> element supports <span>dimension
attributes</span>.</p>
<div class="impl">
<p>The IDL attributes <dfn
title="dom-object-data"><code>data</code></dfn>, <dfn
title="dom-object-type"><code>type</code></dfn>, <dfn
title="dom-object-name"><code>name</code></dfn>, and <dfn
title="dom-object-useMap"><code>useMap</code></dfn> each must
<span>reflect</span> the respective content attributes of the same
name.</p>
<p>The <dfn
title="dom-object-contentDocument"><code>contentDocument</code></dfn>
IDL attribute must return the <code>Document</code> object of the
<span>active document</span> of the <code>object</code> element's
<span>nested browsing context</span>, if it has one; otherwise, it
must return null.</p>
<p>The <dfn
title="dom-object-contentWindow"><code>contentWindow</code></dfn>
IDL attribute must return the <code>WindowProxy</code> object of the
<code>object</code> element's <span>nested browsing context</span>,
if it has one; otherwise, it must return null.</p>
<p>The <code title="dom-cva-willValidate">willValidate</code>,
<code title="dom-cva-validity">validity</code>, and <code
title="dom-cva-validationMessage">validationMessage</code>
attributes, and the <code
title="dom-cva-checkValidatity">checkValidity()</code> and
<code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
methods, are part of the <span>constraint validation API</span>.</p>
</div>
<div class="example">
<p>In the following example, a Java applet is embedded in a page
using the <code>object</code> element. (Generally speaking, it is
better to avoid using applets like these and instead use native
JavaScript and HTML to provide the functionality, since that way
the application will work on all Web browsers without requiring a
third-party plugin. Many devices, especially embedded devices, do
not support third-party technologies like Java.)</p>
<pre><figure>
<dd>
<object type="application/x-java-applet">
<param name="code" value="MyJavaClass">
<p>You do not have Java available, or it is disabled.</p>
</object>
</dd>
<dt>My Java Clock</dt>
</figure></pre>
</div>
<div class="example">
<p>In this example, an HTML page is embedded in another using the
<code>object</code> element.</p>
<pre><figure>
<dd><object data="clock.html"></object>
<dt>My HTML Clock
</figure></pre>
</div>
<h4>The <dfn><code>param</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of an <code>object</code> element, before any <span>flow content</span>.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-param-name">name</code></dd>
<dd><code title="attr-param-value">value</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLParamElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-param-name">name</span>;
attribute DOMString <span title="dom-param-value">value</span>;
};</pre>
</dd>
</dl>
<p>The <code>param</code> element defines parameters for plugins
invoked by <code>object</code> elements. It does not <span
title="represents">represent</span> anything on its own.</p>
<p>The <dfn title="attr-param-name"><code>name</code></dfn>
attribute gives the name of the parameter.</p>
<p>The <dfn title="attr-param-value"><code>value</code></dfn>
attribute gives the value of the parameter.</p>
<p>Both attributes must be present. They may have any value.</p>
<div class="impl">
<p>If both attributes are present, and if the parent element of the
<code>param</code> is an <code>object</code> element, then the
element defines a <dfn
title="concept-param-parameter">parameter</dfn> with the given
name/value pair.</p>
<p>The IDL attributes <dfn
title="dom-param-name"><code>name</code></dfn> and <dfn
title="dom-param-value"><code>value</code></dfn> must both
<span>reflect</span> the respective content attributes of the same
name.</p>
</div>
<div class="example">
<p>The following example shows how the <code>param</code> element
can be used to pass a parameter to a plugin, in this case the Flash
plugin.</p>
<pre><!DOCTYPE HTML>
<html lang="en">
<head>
<title>Flash test page</title>
</head>
<body>
<p>
<object type="application/x-shockwave-flash">
<strong><param name=movie value="http://www.macromedia.com/shockwave/download/triggerpages_mmcom/flash.swf"></strong>
This page requires the use of a proprietary technology. Since you
have not installed the software product required to view this
page, you should try visiting another site that instead uses open
vendor-neutral technologies.
</object>
</p>
</body>
</html></pre>
</div>
<h4 id="video">The <dfn><code>video</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Embedded content</span>.</dd>
<dd>If the element has a <code title="attr-media-controls">controls</code> attribute: <span>Interactive content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>embedded content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>If the element has a <code title="attr-media-src">src</code> attribute: <span>transparent</span>, but with no <span>media element</span> descendants.</dd>
<dd>If the element does not have a <code title="attr-media-src">src</code> attribute: one or more <code>source</code> elements, then, <span>transparent</span>, but with no <span>media element</span> descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-media-src">src</code></dd>
<dd><code title="attr-video-poster">poster</code></dd>
<dd><code title="attr-media-autobuffer">autobuffer</code></dd>
<dd><code title="attr-media-autoplay">autoplay</code></dd>
<dd><code title="attr-media-loop">loop</code></dd>
<dd><code title="attr-media-controls">controls</code></dd>
<dd><code title="attr-dim-width">width</code></dd>
<dd><code title="attr-dim-height">height</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLVideoElement</dfn> : <span>HTMLMediaElement</span> {
attribute DOMString <span title="dom-dim-width">width</span>;
attribute DOMString <span title="dom-dim-height">height</span>;
readonly attribute unsigned long <span title="dom-video-videoWidth">videoWidth</span>;
readonly attribute unsigned long <span title="dom-video-videoHeight">videoHeight</span>;
attribute DOMString <span title="dom-video-poster">poster</span>;
};</pre>
</dd>
</dl>
<p>A <code>video</code> element is used for playing videos or
movies.</p>
<p>Content may be provided inside the <code>video</code>
element<span class="impl">. User agents should not show this content
to the user</span>; it is intended for older Web browsers which do
not support <code>video</code>, so that legacy video plugins can be
tried, or to show text to the users of these older browsers informing
them of how to access the video contents.</p>
<p class="note">In particular, this content is not intended to
address accessibility concerns. To make video content accessible to
the blind, deaf, and those with other physical or cognitive
disabilities, authors are expected to provide alternative media
streams and/or to embed accessibility aids (such as caption or
subtitle tracks) into their media streams.</p>
<p>The <code>video</code> element is a <span>media element</span>
whose <span>media data</span> is ostensibly video data, possibly
with associated audio data.</p>
<p>The <code title="attr-media-src">src</code>, <code
title="attr-media-autobuffer">autobuffer</code>, <code
title="attr-media-autoplay">autoplay</code>, <code
title="attr-media-loop">loop</code>, and <code
title="attr-media-controls">controls</code> attributes are <span
title="media element attributes">the attributes common to all media
elements</span>.</p>
<p>The <dfn title="attr-video-poster"><code>poster</code></dfn>
attribute gives the address of an image file that the user agent can
show while no video data is available. The attribute, if present,
must contain a <span>valid URL</span>. <span class="impl">If the
specified resource is to be used, then, when the element is created
or when the <code title="attr-video-poster">poster</code> attribute
is set, its value must be <span title="resolve a
url">resolved</span> relative to the element, and if that is
successful, the resulting <span>absolute URL</span> must be <span
title="fetch">fetched</span>, from the element's
<code>Document</code>'s <span>origin</span>; this must <span>delay
the load event</span> of the element's document. The <dfn>poster
frame</dfn> is then the image obtained from that resource, if
any.</span></p> <!-- thus it is unaffected by changes to the base
URL. -->
<p class="note">The image given by the <code
title="attr-video-poster">poster</code> attribute, the <i>poster
frame</i>, is intended to be a representative frame of the video
(typically one of the first non-blank frames) that gives the user an
idea of what the video is like.</p>
<div class="impl">
<p>The <dfn title="dom-video-poster"><code>poster</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-video-poster">poster</code> content attribute.</p>
<hr>
<p>When no video data is available (the element's <code
title="dom-media-readyState">readyState</code> attribute is either
<code title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code>, or <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code> but no video
data has yet been obtained at all), the <code>video</code> element
<span>represents</span> either the <span>poster frame</span>, or
nothing.</p>
<p>When a <code>video</code> element is <span
title="dom-media-paused">paused</span> and the <span title="current
playback position">current playback position</span> is the first
frame of video, the element <span>represents</span> either the frame
of video corresponding to the <span title="current playback
position">current playback position</span> or the <span>poster
frame</span>, at the discretion of the user agent.</p>
<p>Notwithstanding the above, the <span>poster frame</span> should
be preferred over nothing, but the <span>poster frame</span> should
not be shown again after a frame of video has been shown.</p>
<p>When a <code>video</code> element is <span
title="dom-media-paused">paused</span> at any other position, the
element <span>represents</span> the frame of video corresponding to
the <span title="current playback position">current playback
position</span>, or, if that is not yet available (e.g. because the
video is seeking or buffering), the last frame of the video to have
been rendered.</p>
<p>When a <code>video</code> element is <span>potentially
playing</span>, it <span>represents</span> the frame of video at the
continuously increasing <span title="current playback
position">"current" position</span>. When the <span>current playback
position</span> changes such that the last frame rendered is no
longer the frame corresponding to the <span>current playback
position</span> in the video, the new frame must be
rendered. Similarly, any audio associated with the video must, if
played, be played synchronized with the <span>current playback
position</span>, at the specified <span
title="dom-media-volume">volume</span> with the specified <span
title="dom-media-muted">mute state</span>.</p>
<p>When a <code>video</code> element is neither <span>potentially
playing</span> nor <span title="dom-media-paused">paused</span>
(e.g. when seeking or stalled), the element <span>represents</span>
the last frame of the video to have been rendered.</p>
<p class="note">Which frame in a video stream corresponds to a
particular playback position is defined by the video stream's
format.</p>
<p>In addition to the above, the user agent may provide messages to
the user (such as "buffering", "no video loaded", "error", or more
detailed information) by overlaying text or icons on the video or
other areas of the element's playback area, or in another
appropriate manner.</p>
<p>User agents that cannot render the video may instead make the
element <span title="represents">represent</span> a link to an
external video playback utility or to the video data itself.</p>
<hr>
</div>
<dl class="domintro">
<dt><var title="">video</var> . <code title="dom-video-videoWidth">videoWidth</code></dt>
<dt><var title="">video</var> . <code title="dom-video-videoHeight">videoHeight</code></dt>
<dd>
<p>These attributes return the intrinsic dimensions of the video,
or zero if the dimensions are not known.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="concept-video-intrinsic-width">intrinsic
width</dfn> and <dfn
title="concept-video-intrinsic-height">intrinsic height</dfn> of the
<span>media resource</span> are the dimensions of the resource in
CSS pixels after taking into account the resource's dimensions,
aspect ratio, clean aperture, resolution, and so forth, as defined
for the format used by the resource. If an anamorphic format does
not define how to apply the aspect ratio to the video data's
dimensions to obtain the "correct" dimensions, then the user agent
must apply the ratio by increasing one dimension and leaving the
other unchanged.</p>
<p>The <dfn
title="dom-video-videoWidth"><code>videoWidth</code></dfn> IDL
attribute must return the <span
title="concept-video-intrinsic-width">intrinsic width</span> of the
video in CSS pixels. The <dfn
title="dom-video-videoHeight"><code>videoHeight</code></dfn> IDL
attribute must return the <span
title="concept-video-intrinsic-height">intrinsic height</span> of
the video in CSS pixels. If the element's <code
title="dom-media-readyState">readyState</code> attribute is <code
title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code>, then the
attributes must return 0.</p>
</div>
<p>The <code>video</code> element supports <span>dimension
attributes</span>.</p>
<div class="impl">
<p>Video content should be rendered inside the element's playback
area such that the video content is shown centered in the playback
area at the largest possible size that fits completely within it,
with the video content's aspect ratio being preserved. Thus, if the
aspect ratio of the playback area does not match the aspect ratio of
the video, the video will be shown letterboxed or pillarboxed. Areas
of the element's playback area that do not contain the video
represent nothing.</p>
<p>The intrinsic width of a <code>video</code> element's playback
area is the <span title="concept-video-intrinsic-width">intrinsic
width</span> of the video resource, if that is available; otherwise
it is the intrinsic width of the <span>poster frame</span>, if that
is available; otherwise it is 300 CSS pixels.</p>
<p>The intrinsic height of a <code>video</code> element's playback
area is the <span title="concept-video-intrinsic-height">intrinsic
height</span> of the video resource, if that is available; otherwise
it is the intrinsic height of the <span>poster frame</span>, if that
is available; otherwise it is 150 CSS pixels.</p>
<hr>
<p>User agents should provide controls to enable or disable the
display of closed captions associated with the video stream, though
such features should, again, not interfere with the page's normal
rendering.</p>
<p>User agents may allow users to view the video content in manners
more suitable to the user (e.g. full-screen or in an independent
resizable window). As for the other user interface features,
controls to enable this should not interfere with the page's normal
rendering unless the user agent is <span title="expose a user
interface to the user">exposing a user interface</span>. In such an
independent context, however, user agents may make full user
interfaces visible, with, e.g., play, pause, seeking, and volume
controls, even if the <code
title="attr-media-controls">controls</code> attribute is absent.</p>
<p>User agents may allow video playback to affect system features
that could interfere with the user's experience; for example, user
agents could disable screensavers while video playback is in
progress.</p>
<p class="warning">User agents should not provide a public API to
cause videos to be shown full-screen. A script, combined with a
carefully crafted video file, could trick the user into thinking a
system-modal dialog had been shown, and prompt the user for a
password. There is also the danger of "mere" annoyance, with pages
launching full-screen videos when links are clicked or pages
navigated. Instead, user-agent-specific interface features may be
provided to easily allow the user to obtain a full-screen playback
mode.</p>
</div>
<!--CODECS
<div class="impl">
<h5>Video and audio codecs for <code>video</code> elements</h5>
<p>User agents may support any video and audio codecs and container
formats.</p>
<p class="note">Certain user agents might support no codecs at all,
e.g. text browsers running over SSH connections.</p>
<!- - similar note in audio codecs section - ->
<p class="note">Implementations are free to implement support for
video codecs either natively, or using platform-specific APIs, or
using plugins: this specification does not specify how codecs are to
be implemented.</p>
</div>
(when replacing this text, also fix "- -" nested comments)-->
<h4 id="audio">The <dfn><code>audio</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Embedded content</span>.</dd>
<dd>If the element has a <code title="attr-media-controls">controls</code> attribute: <span>Interactive content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>embedded content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>If the element has a <code title="attr-media-src">src</code> attribute: <span>transparent</span>, but with no <span>media element</span> descendants.</dd>
<dd>If the element does not have a <code title="attr-media-src">src</code> attribute: one or more <code>source</code> elements, then, <span>transparent</span>, but with no <span>media element</span> descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-media-src">src</code></dd>
<dd><code title="attr-media-autobuffer">autobuffer</code></dd>
<dd><code title="attr-media-autoplay">autoplay</code></dd>
<dd><code title="attr-media-loop">loop</code></dd>
<dd><code title="attr-media-controls">controls</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">[NamedConstructor=<span title="dom-Audio">Audio</span>(),
NamedConstructor=<span title="dom-Audio-s">Audio</span>(in DOMString src)]
interface <dfn>HTMLAudioElement</dfn> : <span>HTMLMediaElement</span> {};</pre>
</dd>
</dl>
<p>An <code>audio</code> element <span>represents</span> a sound or
audio stream.</p>
<!-- v2 (actually v3) suggestions:
* Audio syntesis. Use cases from Charles Pritchard:
> Use a sound of varying pitch to hint to a user the location of their
> mouse (is it hovering over a button, is it x/y pixels away from the edge
> of the screen, how close is it to the center).
>
> Alter the pitch of a sound to make a very cheap midi instrument.
>
> Pre-mix a few generated sounds, because the client processor is slow.
>
> Alter the pitch of an actual audio recording, and pre-mix it, to give
> different sounding voices to pre-recorded readings of a single text. As
> has been tried for "male" "female" sound fonts.
>
> Support very simple audio codecs, and programmable synthesizers.
-->
<p>Content may be provided inside the <code>audio</code>
element<span class="impl">. User agents should not show this content
to the user</span>; it is intended for older Web browsers which do
not support <code>audio</code>, so that legacy audio plugins can be
tried, or to show text to the users of these older browsers informing
them of how to access the audio contents.</p>
<p class="note">In particular, this content is not intended to
address accessibility concerns. To make audio content accessible to
the deaf or to those with other physical or cognitive disabilities,
authors are expected to provide alternative media streams and/or to
embed accessibility aids (such as transcriptions) into their media
streams.</p>
<p>The <code>audio</code> element is a <span>media element</span>
whose <span>media data</span> is ostensibly audio data.</p>
<p>The <code title="attr-media-src">src</code>, <code
title="attr-media-autobuffer">autobuffer</code>, <code
title="attr-media-autoplay">autoplay</code>, <code
title="attr-media-loop">loop</code>, and <code
title="attr-media-controls">controls</code> attributes are <span
title="media element attributes">the attributes common to all media
elements</span>.</p>
<div class="impl">
<p>When an <code>audio</code> element is <span>potentially
playing</span>, it must have its audio data played synchronized with
the <span>current playback position</span>, at the specified <span
title="dom-media-volume">volume</span> with the specified <span
title="dom-media-muted">mute state</span>.</p>
<p>When an <code>audio</code> element is not <span>potentially
playing</span>, audio must not play for the element.</p>
</div>
<dl class="domintro">
<dt><var title="">audio</var> = new <code title="dom-Audio">Audio</code>( [ <var title="">url</var> ] )</dt>
<dd>
<p>Returns a new <code>audio</code> element, with the <code
title="attr-media-src">src</code> attribute set to the value
passed in the argument, if applicable.</p>
</dd>
</dl>
<div class="impl">
<p>Two constructors are provided for creating
<code>HTMLAudioElement</code> objects (in addition to the factory
methods from DOM Core such as <code
title="">createElement()</code>): <dfn
title="dom-Audio"><code>Audio()</code></dfn> and <dfn
title="dom-Audio-s"><code>Audio(<var
title="">src</var>)</code></dfn>. When invoked as constructors,
these must return a new <code>HTMLAudioElement</code> object (a new
<code>audio</code> element). The element must have its <code
title="attr-media-autobuffer">autobuffer</code> attribute set to the
literal value "<code title="">autobuffer</code>". If the <var
title="">src</var> argument is present, the object created must have
its <code title="attr-media-src">src</code> content attribute set to
the provided value, and the user agent must invoke the object's
<span title="concept-media-load-algorithm">resource selection
algorithm</span> before returning. The element's document must be
the <span>active document</span> of the <span>browsing
context</span> of the <code>Window</code> object on which the
interface object of the invoked constructor is found.</p>
</div>
<!--CODECS
<div class="impl">
<h5>Audio codecs for <code>audio</code> elements</h5>
<p>User agents may support any audio codecs and container
formats.</p>
<p>User agents must support the WAVE container format with audio
encoded using the 16 bit PCM (LE) codec, at sampling frequencies of
11.025kHz, 22.050kHz, and 44.100kHz, and for both mono and
stereo. <a href="#- -refsWAVE">[WAVE]</a></p>
<!- -
<dt id="- -refsWAVE">WAVE</dt>
<dd>http://en.wikipedia.org/wiki/WAV? </dd>
- ->
<!- - similar note in video codecs section - ->
<p class="note">Implementations are free to implement support for
audio codecs either natively, or using platform-specific APIs, or
using plugins: this specification does not specify how codecs are to
be implemented.</p>
</div>
(when replacing this text, also fix "- -" nested comments)-->
<h4>The <dfn><code>source</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <span>media element</span>, before any <span>flow content</span>.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-source-src">src</code></dd>
<dd><code title="attr-source-type">type</code></dd>
<dd><code title="attr-source-media">media</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLSourceElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-source-src">src</span>;
attribute DOMString <span title="dom-source-type">type</span>;
attribute DOMString <span title="dom-source-media">media</span>;
};</pre>
</dd>
</dl>
<p>The <code>source</code> element allows authors to specify
multiple <span title="media resource">media resources</span> for
<span title="media element">media elements</span>. It does not <span
title="represents">represent</span> anything on its own.</p>
<p>The <dfn title="attr-source-src"><code>src</code></dfn> attribute
gives the address of the <span>media resource</span>. The value must
be a <span>valid URL</span>. This attribute must be present.</p>
<p>The <dfn title="attr-source-type"><code>type</code></dfn>
attribute gives the type of the <span>media resource</span>, to help
the user agent determine if it can play this <span>media
resource</span> before fetching it. If specified, its value must be
a <span>valid MIME type</span>. The <code title="">codecs</code>
parameter may be specified and might be necessary to specify exactly
how the resource is encoded. <a
href="#refsRFC4281">[RFC4281]</a></p>
<div class="example">
<p>The following list shows some examples of how to use the <code
title="">codecs=</code> MIME parameter in the <code
title="attr-source-type">type</code> attribute.</p>
<dl>
<dt>H.264 Simple baseline profile video (main and extended video compatible) level 3 and Low-Complexity AAC audio in MP4 container</dt>
<dd><pre><source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'></pre></dd>
<dt>H.264 Extended profile video (baseline-compatible) level 3 and Low-Complexity AAC audio in MP4 container</dt>
<dd><pre><source src='video.mp4' type='video/mp4; codecs="avc1.58A01E, mp4a.40.2"'></pre></dd>
<dt>H.264 Main profile video level 3 and Low-Complexity AAC audio in MP4 container</dt>
<dd><pre><source src='video.mp4' type='video/mp4; codecs="avc1.4D401E, mp4a.40.2"'></pre></dd>
<dt>H.264 'High' profile video (incompatible with main, baseline, or extended profiles) level 3 and Low-Complexity AAC audio in MP4 container</dt>
<dd><pre><source src='video.mp4' type='video/mp4; codecs="avc1.64001E, mp4a.40.2"'></pre></dd>
<dt>MPEG-4 Visual Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container</dt>
<dd><pre><source src='video.mp4' type='video/mp4; codecs="mp4v.20.8, mp4a.40.2"'></pre></dd>
<dt>MPEG-4 Advanced Simple Profile Level 0 video and Low-Complexity AAC audio in MP4 container</dt>
<dd><pre><source src='video.mp4' type='video/mp4; codecs="mp4v.20.240, mp4a.40.2"'></pre></dd>
<dt>MPEG-4 Visual Simple Profile Level 0 video and AMR audio in 3GPP container</dt>
<dd><pre><source src='video.3gp' type='video/3gpp; codecs="mp4v.20.8, samr"'></pre></dd>
<dt>Theora video and Vorbis audio in Ogg container</dt>
<dd><pre><source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'></pre></dd>
<dt>Theora video and Speex audio in Ogg container</dt>
<dd><pre><source src='video.ogv' type='video/ogg; codecs="theora, speex"'></pre></dd>
<dt>Vorbis audio alone in Ogg container</dt>
<dd><pre><source src='audio.ogg' type='audio/ogg; codecs=vorbis'></pre></dd>
<dt>Speex audio alone in Ogg container</dt>
<dd><pre><source src='audio.spx' type='audio/ogg; codecs=speex'></pre></dd>
<dt>FLAC audio alone in Ogg container</dt>
<dd><pre><source src='audio.oga' type='audio/ogg; codecs=flac'></pre></dd>
<dt>Dirac video and Vorbis audio in Ogg container</dt>
<dd><pre><source src='video.ogv' type='video/ogg; codecs="dirac, vorbis"'></pre></dd>
<dt>Theora video and Vorbis audio in Matroska container</dt>
<dd><pre><source src='video.mkv' type='video/x-matroska; codecs="theora, vorbis"'></pre></dd>
<!-- awaiting definition by the Ogg or BBC guys:
<dt>Dirac video and Vorbis audio in Matroska container</dt>
<dd><pre><source src='video.mkv' type='video/x-matroska; codecs='></pre></dd>
-->
<!-- awaiting definition by the Microsoft guys:
<dt>WMV9 video and WMA 2 audio in ASF container</dt>
<dd><pre><source src='video.wmv' type='video/x-ms-wmv; codecs='></pre></dd>
<dt>WMV8 video and WMA 2 audio in ASF container</dt>
<dd><pre><source src='video.wmv' type='video/x-ms-wmv; codecs='></pre></dd>
<dt>VC-1 video and WMA 10 Pro audio in ASF container</dt>
<dd><pre><source src='video.wmv' type='video/x-ms-wmv; codecs='></pre></dd>
<dt>XviD video and MP3 audio in AVI container</dt>
<dd><pre><source src='video.avi' type='video/x-msvideo; codecs='></pre></dd>
<dt>Motion-JPEG video and uncompressed PCM audio in AVI container</dt>
<dd><pre><source src='video.avi' type='video/x-msvideo; codecs='></pre></dd>
-->
<!-- awaiting definition by Real:
<dt>Real Video 10 video and High-Efficiency AAC audio in Real Media container</dt>
<dd><pre><source src='video.rm' type='application/vnd.rn-realmedia; codecs='></pre></dd>
-->
<!-- undefined:
<dt>MPEG-1 video and MPEG-1 Audio Layer II audio in MPEG-1 program stream</dt>
<dd><pre><source src='video.mpg' type='video/mpeg; codecs='></pre></dd>
-->
</dl>
</div>
<p>The <dfn title="attr-source-media"><code>media</code></dfn>
attribute gives the intended media type of the <span>media
resource</span>, to help the user agent determine if this
<span>media resource</span> is useful to the user before fetching
it. Its value must be a <span>valid media query</span>.</p>
<p id="source-default-media">The default, if the <code
title="attr-srouce-media">media</code> attribute is omitted, is
"<code title="">all</code>", meaning that by default styles apply to
all media.</p>
<div class="impl">
<p>If a <code>source</code> element is inserted as a child of a
<span>media element</span> that has no <code
title="attr-media-src">src</code> attribute and whose <code
title="dom-media-networkState">networkState</code> has the value
<code title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code>, the user
agent must invoke the <span>media element</span>'s <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</p>
<p>The IDL attributes <dfn
title="dom-source-src"><code>src</code></dfn>, <dfn
title="dom-source-type"><code>type</code></dfn>, and <dfn
title="dom-source-media"><code>media</code></dfn> must
<span>reflect</span> the respective content attributes of the same
name.</p>
</div>
<h4>Media elements</h4>
<p><dfn title="media element">Media elements</dfn> implement the
following interface:</p>
<pre class="idl">interface <dfn>HTMLMediaElement</dfn> : <span>HTMLElement</span> {
// error state
readonly attribute <span>MediaError</span> <span title="dom-media-error">error</span>;
// network state
attribute DOMString <span title="dom-media-src">src</span>;
readonly attribute DOMString <span title="dom-media-currentSrc">currentSrc</span>;
const unsigned short <span title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</span> = 0;
const unsigned short <span title="dom-media-NETWORK_IDLE">NETWORK_IDLE</span> = 1;
const unsigned short <span title="dom-media-NETWORK_LOADING">NETWORK_LOADING</span> = 2;
const unsigned short <span title="dom-media-NETWORK_NO_SOURCE">NETWORK_NO_SOURCE</span> = 3;
readonly attribute unsigned short <span title="dom-media-networkState">networkState</span>;
attribute boolean <span title="dom-media-autobuffer">autobuffer</span>;
<!--v3BUF readonly attribute float <span title="dom-media-bufferingRate">bufferingRate</span>;
readonly attribute boolean <span title="dom-media-bufferingThrottled">bufferingThrottled</span>;
--> readonly attribute <span>TimeRanges</span> <span title="dom-media-buffered">buffered</span>;
void <span title="dom-media-load">load</span>();
DOMString <span title="dom-navigator-canPlayType">canPlayType</span>(in DOMString type);
// ready state
const unsigned short <span title="dom-media-HAVE_NOTHING">HAVE_NOTHING</span> = 0;
const unsigned short <span title="dom-media-HAVE_METADATA">HAVE_METADATA</span> = 1;
const unsigned short <span title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</span> = 2;
const unsigned short <span title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</span> = 3;
const unsigned short <span title="dom-media-HAVE_ENOUGH_DATA">HAVE_ENOUGH_DATA</span> = 4;
readonly attribute unsigned short <span title="dom-media-readyState">readyState</span>;
readonly attribute boolean <span title="dom-media-seeking">seeking</span>;
// playback state
attribute float <span title="dom-media-currentTime">currentTime</span>;
readonly attribute float <span title="dom-media-startTime">startTime</span>;
readonly attribute float <span title="dom-media-duration">duration</span>;
readonly attribute boolean <span title="dom-media-paused">paused</span>;
attribute float <span title="dom-media-defaultPlaybackRate">defaultPlaybackRate</span>;
attribute float <span title="dom-media-playbackRate">playbackRate</span>;
readonly attribute <span>TimeRanges</span> <span title="dom-media-played">played</span>;
readonly attribute <span>TimeRanges</span> <span title="dom-media-seekable">seekable</span>;
readonly attribute boolean <span title="dom-media-ended">ended</span>;
attribute boolean <span title="dom-media-autoplay">autoplay</span>;
attribute boolean <span title="dom-media-loop">loop</span>;
void <span title="dom-media-play">play</span>();
void <span title="dom-media-pause">pause</span>();
<!--v2CUERANGE
// cue ranges
void <span title="dom-media-addCueRange">addCueRange</span>(in DOMString className, in DOMString id, in float start, in float end, in boolean pauseOnExit, in <span>CueRangeCallback</span> enterCallback, in <span>CueRangeCallback</span> exitCallback);
void <span title="dom-media-removeCueRanges">removeCueRanges</span>(in DOMString className);
-->
// controls
attribute boolean <span title="dom-media-controls">controls</span>;
attribute float <span title="dom-media-volume">volume</span>;
attribute boolean <span title="dom-media-muted">muted</span>;
};<!--v2CUERANGE
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>CueRangeCallback</dfn> {
void <span title="dom-CueRangeCallback-handleEvent">handleEvent</span>(in DOMString id);
};--></pre>
<p>The <dfn>media element attributes</dfn>, <code
title="attr-media-src">src</code>, <code
title="attr-media-autobuffer">autobuffer</code>, <code
title="attr-media-autoplay">autoplay</code>, <code
title="attr-media-loop">loop</code>, and <code
title="attr-media-controls">controls</code>, apply to all <span
title="media element">media elements</span>. They are defined in
this section.</p>
<!-- proposed v2 (actually v3!) features:
* frame forward / backwards / step(n) while paused
* hasAudio, hasVideo, hasCaptions, etc
* per-frame control: get current frame; set current frame
* queue of content
- pause current stream and insert content at front of queue to play immediately
- pre-download another stream
- add stream(s) to play at end of current stream
- pause playback upon reaching a certain time
- playlists, with the ability to get metadata out of them (e.g. xspf)
* control over closed captions:
- enable, disable, select language
- event that sends caption text to script
* in-band metadata and cue points to allow:
- Chapter markers that synchronize to playback (without having to poll
the playhead position)
- Annotations on video content (i.e., pop-up video)
- General custom metadata store (ratings, etc.)
* notification of chapter labels changing on the fly:
- onchapterlabelupdate, which has a time and a label
* cue points that trigger at fixed intervals, so that
e.g. animation can be synced with the video
* general meta data, implemented as getters (don't expose the whole thing)
- getMetadata(key: string, language: string) => HTMLImageElement or string
- onmetadatachanged (no context info)
* external captions support (request from John Foliot)
* video: applying CSS filters
* an event to notify people of when the video size changes
(e.g. for chained Ogg streams of multiple independent videos)
* balance and 3D position audio
* audio filters
* audio synthesis (see <audio> section for use cases)
* feedback to the script on how well the video is playing
- frames per second?
- skipped frames per second?
- an event that reports playback difficulties?
- an arbitrary quality metric?
* bufferingRate/bufferingThrottled (see v3BUF)
* events for when the user agent's controls get shown or hidden
so that the author's controls can get away of the UA's
-->
<!-- v2 features that already have experimental implementations:
* webkitPreservesPitch (for when playbackRate != 1.0)
-->
<p><span title="media element">Media elements</span> are used to
present audio data, or video and audio data, to the user. This is
referred to as <dfn>media data</dfn> in this section, since this
section applies equally to <span title="media element">media
elements</span> for audio or for video. The term <dfn>media
resource</dfn> is used to refer to the complete set of media data,
e.g. the complete video file, or complete audio file.</p>
<div class="impl">
<p>Except where otherwise specified, the <span>task source</span>
for all the tasks <span title="queue a task">queued</span> in this
section and its subsections is the <dfn>media element event task
source</dfn>.</p>
</div>
<h5>Error codes</h5>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-error">error</code></dt>
<dd>
<p>Returns a <code>MediaError</code> object representing the
current error state of the element.</p>
<p>Returns null if there is no error.</p>
</dd>
</dl>
<div class="impl">
<p>All <span title="media element">media elements</span> have an
associated error status, which records the last error the element
encountered since its <span
title="concept-media-load-algorithm">resource selection
algorithm</span> was last invoked. The <dfn
title="dom-media-error"><code>error</code></dfn> attribute, on
getting, must return the <code>MediaError</code> object created for
this last error, or null if there has not been an error.</p>
</div>
<pre class="idl">interface <dfn>MediaError</dfn> {
const unsigned short <span title="dom-MediaError-MEDIA_ERR_ABORTED">MEDIA_ERR_ABORTED</span> = 1;
const unsigned short <span title="dom-MediaError-MEDIA_ERR_NETWORK">MEDIA_ERR_NETWORK</span> = 2;
const unsigned short <span title="dom-MediaError-MEDIA_ERR_DECODE">MEDIA_ERR_DECODE</span> = 3;
const unsigned short <span title="dom-MediaError-MEDIA_ERR_SRC_NOT_SUPPORTED">MEDIA_ERR_SRC_NOT_SUPPORTED</span> = 4;
readonly attribute unsigned short <span title="dom-MediaError-code">code</span>;
};</pre>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-error">error</code> . <code title="dom-MediaError-code">code</code></dt>
<dd>
<p>Returns the current error's error code, from the list below.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-MediaError-code"><code>code</code></dfn>
attribute of a <code>MediaError</code> object must return the code
for the error, which must be one of the following:</p>
</div>
<dl>
<dt><dfn title="dom-MediaError-MEDIA_ERR_ABORTED"><code>MEDIA_ERR_ABORTED</code></dfn> (numeric value 1)</dt>
<dd>The fetching process for the <span>media resource</span> was
aborted by the user agent at the user's request.</dd>
<dt><dfn title="dom-MediaError-MEDIA_ERR_NETWORK"><code>MEDIA_ERR_NETWORK</code></dfn> (numeric value 2)</dt>
<dd>A network error of some description caused the user agent to
stop fetching the <span>media resource</span>, after the resource
was established to be usable.</dd>
<dt><dfn title="dom-MediaError-MEDIA_ERR_DECODE"><code>MEDIA_ERR_DECODE</code></dfn> (numeric value 3)</dt>
<dd>An error of some description occurred while decoding the
<span>media resource</span>, after the resource was established to
be usable.</dd>
<dt><dfn title="dom-MediaError-MEDIA_ERR_SRC_NOT_SUPPORTED"><code>MEDIA_ERR_SRC_NOT_SUPPORTED</code></dfn> (numeric value 4)</dt>
<dd>The <span>media resource</span> indicated by the <code
title="attr-media-src">src</code> attribute was not suitable.</dd>
</dl>
<h5>Location of the media resource</h5>
<p>The <dfn title="attr-media-src"><code>src</code></dfn> content
attribute on <span title="media element">media elements</span> gives
the address of the media resource (video, audio) to show. The
attribute, if present, must contain a <span>valid URL</span>.</p>
<div class="impl">
<p>If a <code title="attr-media-src">src</code> attribute of a
<span>media element</span> is set or changed, the user agent must
invoke the <span>media element</span>'s <span>media element load
algorithm</span>. (<em>Removing</em> the <code
title="attr-media-src">src</code> attribute does not do this, even
if there are <code>source</code> elements present.)</p>
<p>The <dfn title="dom-media-src"><code>src</code></dfn> IDL
attribute on <span title="media element">media elements</span> must
<span>reflect</span> the content attribute of the same name.</p>
</div>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-currentSrc">currentSrc</code></dt>
<dd>
<p>Returns the address of the current <span>media resource</span>.</p>
<p>Returns the empty string when there is no <span>media resource</span>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-media-currentSrc"><code>currentSrc</code></dfn> IDL
attribute is initially the empty string. Its value is changed by the
<span title="concept-media-load-algorithm">resource selection
algorithm</span> defined below.</p>
</div>
<p class="note">There are two ways to specify a <span>media
resource</span>, the <code title="attr-media-src">src</code>
attribute, or <code>source</code> elements. The attribute overrides
the elements.</p>
<h5>MIME types</h5>
<p>A <span>media resource</span> can be described in terms of its
<em>type</em>, specifically a <span>MIME type</span>, optionally
with a <code title="">codecs</code> parameter. <a
href="#refsRFC4281">[RFC4281]</a></p>
<p>Types are usually somewhat incomplete descriptions; for example
"<code title="">video/mpeg</code>" doesn't say anything except what
the container type is, and even a type like "<code
title="">video/mp4; codecs="avc1.42E01E,
mp4a.40.2"</code>" doesn't include information like the actual
bitrate (only the maximum bitrate). Thus, given a type, a user agent
can often only know whether it <em>might</em> be able to play
media of that type (with varying levels of confidence), or whether
it definitely <em>cannot</em> play media of that type.</p>
<p><dfn>A type that the user agent knows it cannot render</dfn> is
one that describes a resource that the user agent definitely does
not support, for example because it doesn't recognize the container
type, or it doesn't support the listed codecs.</p>
<p>The <span>MIME type</span> "<code
title="">application/octet-stream</code>" with no parameters is
never <span>a type that the user agent knows it cannot
render</span>. User agents must treat that type as equivalent to the
lack of any explicit <span title="Content-Type">Content-Type
metadata</span> when it is used to label a potential <span>media
resource</span>.</p>
<p class="note">In the absence of a <!-- pretty crazy -->
specification to the contrary, the <span>MIME type</span> "<code
title="">application/octet-stream</code>" when used <em>with</em>
parameters, e.g. "<code
title="">application/octet-stream;codecs=theora</code>", <em>is</em>
<span>a type that the user agent knows it cannot render</span>.</p>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-navigator-canPlayType">canPlayType</code>(<var title="">type</var>)</dt>
<dd>
<p>Returns the empty string (a negative response), "maybe", or
"probably" based on how confident the user agent is that it can
play media resources of the given type.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-navigator-canPlayType"><code>canPlayType(<var
title="">type</var>)</code></dfn> method must return the empty
string if <var title="">type</var> is <span>a type that the user
agent knows it cannot render</span>; it must return "<code
title="">probably</code>" if the user agent is confident that the
type represents a <span>media resource</span> that it can render if
used in with this <code>audio</code> or <code>video</code> element;
and it must return "<code title="">maybe</code>"
otherwise. Implementors are encouraged to return "<code
title="">maybe</code>" unless the type can be confidently
established as being supported or not. Generally, a user agent
should never return "<code title="">probably</code>" if the type
doesn't have a <code title="">codecs</code> parameter.</p>
</div>
<div class="example">
<p>This script tests to see if the user agent supports a
(fictional) new format to dynamically decide whether to use a
<code>video</code> element or a plugin:</p>
<pre><section id="video">
<p><a href="playing-cats.nfv">Download video</a></p>
</section>
<script>
var videoSection = document.getElementById('video');
var videoElement = document.createElement('video');
var support = videoElement.canPlayType('video/x-new-fictional-format;codecs="kittens,bunnies"');
if (support != "probably" && "New Fictional Video Plug-in" in navigator.plugins) {
// not confident of browser support
// but we have a plugin
// so use plugin instead
videoElement = document.createElement("embed");
} else if (support == "") {
// no support from browser and no plugin
// do nothing
videoElement = null;
}
if (videoElement) {
while (videoSection.hasChildNodes())
videoSection.removeChild(videoSection.firstChild);
videoElement.setAttribute("src", "playing-cats.nfv");
videoSection.appendChild(videoElement);
}
</script></pre>
</div>
<p class="note">The <code title="attr-source-type">type</code>
attribute of the <code>source</code> element allows the user agent
to avoid downloading resources that use formats it cannot
render.</p>
<h5>Network states</h5>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-networkState">networkState</code></dt>
<dd>
<p>Returns the current state of network activity for the element,
from the codes in the list below.</p>
</dd>
</dl>
<div class="impl">
<p>As <span title="media element">media elements</span> interact
with the network, their current network activity is represented by
the <dfn
title="dom-media-networkState"><code>networkState</code></dfn>
attribute. On getting, it must return the current network state of
the element, which must be one of the following values:</p>
</div>
<dl>
<dt><dfn title="dom-media-NETWORK_EMPTY"><code>NETWORK_EMPTY</code></dfn> (numeric value 0)</dt>
<dd>The element has not yet been initialized. All attributes are in
their initial states.</dd>
<dt><dfn title="dom-media-NETWORK_IDLE"><code>NETWORK_IDLE</code></dfn> (numeric value 1)</dt>
<dd>The element<span class="impl">'s <span
title="concept-media-load-algorithm">resource selection
algorithm</span> is active and</span> has selected a <span
title="media resource">resource</span>, but it is not actually
using the network at this time.</dd>
<dt><dfn title="dom-media-NETWORK_LOADING"><code>NETWORK_LOADING</code></dfn> (numeric value 2)</dt>
<dd>The user agent is actively trying to download data.</dd>
<dt><dfn title="dom-media-NETWORK_NO_SOURCE"><code>NETWORK_NO_SOURCE</code></dfn> (numeric value 3)</dt>
<dd>The element<span class="impl">'s <span
title="concept-media-load-algorithm">resource selection
algorithm</span> is active, but it</span> has failed to find a
<span title="media resource">resource</span> to use.</dd>
</dl>
<div class="impl">
<p>The <span title="concept-media-load-algorithm">resource selection
algorithm</span> defined below describes exactly when the <code
title="dom-media-networkState">networkState</code> attribute changes
value and what events fire to indicate changes in this state.</p>
</div>
<h5>Loading the media resource</h5>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-load">load</code>()</dt>
<dd>
<p>Causes the element to reset and start selecting and loading a
new <span>media resource</span> from scratch.</p>
</dd>
</dl>
<div class="impl">
<p>All <span title="media element">media elements</span> have an
<dfn>autoplaying flag</dfn>, which must begin in the true state, and
a <dfn>delaying-the-load-event flag</dfn>, which must begin in the
false state. While the <span>delaying-the-load-event flag</span> is
true, the element must <span>delay the load event</span> of its
document.</p>
<p>When the <dfn title="dom-media-load"><code>load()</code></dfn>
method on a <span>media element</span> is invoked, the user agent
must run the <span>media element load algorithm</span>.</p>
<p>The <dfn>media element load algorithm</dfn> consists of the
following steps. Note that this algorithm might get aborted, e.g. if
the <code title="dom-media-load">load()</code> method itself is
invoked again.</p>
<ol>
<li><p>Abort any already-running instance of the <span
title="concept-media-load-algorithm">resource selection
algorithm</span> for this element.</p></li>
<li>
<p>If there are any <span title="concept-task">tasks</span> from
the <span>media element</span>'s <span>media element event task
source</span> in one of the <span title="task queue">task
queues</span>, then remove those tasks.</p>
<p class="note">Basically, pending events and callbacks for the
media element are discarded when the media element starts loading
a new resource.</p>
</li>
<li><p>If the <span>media element</span>'s <code
title="dom-media-networkState">networkState</code> is set to <code
title="dom-media-NETWORK_LOADING">NETWORK_LOADING</code> or <code
title="dom-media-NETWORK_IDLE">NETWORK_IDLE</code>, <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-media-abort">abort</code> at the <span>media
element</span>.</p></li>
<li>
<p>If the <span>media element</span>'s <code
title="dom-media-networkState">networkState</code> is not set to
<code title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code>, then
run these substeps:</p>
<ol>
<li><p>If a fetching process is in progress for the <span>media
element</span>, the user agent should stop it.</p></li>
<li>Set the <code
title="dom-media-networkState">networkState</code> attribute to
<span title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</span>.</li>
<li>If <code title="dom-media-readyState">readyState</code> is
not set to <code
title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code>, then set it
to that state.</li>
<li>If the <code title="dom-media-paused">paused</code> attribute
is false, then set to true.</li>
<li>If <code title="dom-media-seeking">seeking</code> is true,
set it to false.</li>
<li>Set the <span>current playback position</span> to 0.</li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code
title="event-media-emptied">emptied</code> at the <span>media
element</span>.</p></li>
</ol>
</li>
<li><p>Set the <code
title="dom-media-playbackRate">playbackRate</code> attribute to the
value of the <code
title="dom-media-defaultPlaybackRate">defaultPlaybackRate</code>
attribute.</p></li>
<li><p>Set the <code title="dom-media-error">error</code> attribute
to null and the <span>autoplaying flag</span> to true.</p></li>
<li><p>Invoke the <span>media element</span>'s <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</li>
<li>
<p class="note">Playback of any previously playing <span>media
resource</span> for this element stops.</p>
</li>
</ol>
<p>The <dfn title="concept-media-load-algorithm">resource selection
algorithm</dfn> for a <span>media element</span> is as follows. This
algorithm is always invoked synchronously, but one of the first
steps in the algorithm is to return and continue running the
remaining steps asynchronously, meaning that it runs in the
background with scripts and other <span
title="concept-task">tasks</span> running in parallel. In addition,
this algorithm interacts closely with the <span>event loop</span>
mechanism; in particular, it has <span title="synchronous
section">synchronous sections</span> (which are triggered as part of
the <span>event loop</span> algorithm). Steps in such sections are
marked with ⌛.</p>
<ol>
<li><p>Set the <code
title="dom-media-networkState">networkState</code> to <code
title="dom-media-NETWORK_NO_SOURCE">NETWORK_NO_SOURCE</code>.</p></li>
<li><p>Asynchronously <span>await a stable state</span>, allowing
the <span title="concept-task">task</span> that invoked this
algorithm to continue. The <span>synchronous section</span>
consists of all the remaining steps of this algorithm until the
algorithm says the <span>synchronous section</span> has
ended. (Steps in <span title="synchronous section">synchronous
sections</span> are marked with ⌛.)</p></li>
<li>
<p>⌛ If the <span>media element</span> has a <code
title="attr-media-src">src</code> attribute, then let <var
title="">mode</var> be <i title="">attribute</i>.</p>
<p>⌛ Otherwise, if the <span>media element</span> does not
have a <code title="attr-media-src">src</code> attribute but has a
<code>source</code> element child, then let <var
title="">mode</var> be <i title="">children</i> and let <var
title="">candidate</var> be the first such <code>source</code>
element child in <span>tree order</span>.</p>
<p>⌛ Otherwise the <span>media element</span> has neither a
<code title="attr-media-src">src</code> attribute nor a
<code>source</code> element child: set the <code
title="dom-media-networkState">networkState</code> to <code
title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code>, and abort
these steps; the <span>synchronous section</span> ends.</p>
</li>
<li><p>⌛ Set the <span>media element</span>'s
<span>delaying-the-load-event flag</span> to true (this <span
title="delay the load event">delays the load event</span>), and set
its <code title="dom-media-networkState">networkState</code> to
<code
title="dom-media-NETWORK_LOADING">NETWORK_LOADING</code>.</p></li>
<li><p>⌛ <span>Queue a task</span> to <span>fire a simple
event</span> named <code
title="event-media-loadstart">loadstart</code> at the <span>media
element</span>.</p></li>
<li>
<p>If <var title="">mode</var> is <i title="">attribute</i>, then
run these substeps:</p>
<ol>
<li><p>⌛ Let <var title="">absolute URL</var> be the
<span>absolute URL</span> that would have resulted from <span
title="resolve a url">resolving</span> the <span>URL</span>
specified by the <code title="attr-media-src">src</code>
attribute's value relative to the <span>media element</span> when
the <code title="attr-media-src">src</code> attribute was last
changed.</p> <!-- i.e. changing xml:base or <base> after src=""
has no effect -->
<li><p>⌛ If <var title="">absolute URL</var> was obtained
successfully, set the <code
title="dom-media-currentSrc">currentSrc</code> attribute to <var
title="">absolute URL</var>.</p></li>
<li><p>End the <span>synchronous section</span>, continuing the
remaining steps asynchronously.</p></li>
<li><p>If <var title="">absolute URL</var> was obtained
successfully, run the <span
title="concept-media-load-resource">resource fetch
algorithm</span> with <var title="">absolute URL</var>. If that
algorithm returns without aborting <em>this</em> one, then the
load failed.</p></li>
<li><p>Reaching this step indicates that the media resource
failed to load or that the given <span>URL</span> could not be
<span title="resolve a url">resolved</span>. Set the <code
title="dom-media-error">error</code> attribute to a new
<code>MediaError</code> object whose <code
title="dom-MediaError-code">code</code> attribute is set to <code
title="dom-MediaError-MEDIA_ERR_SRC_NOT_SUPPORTED">MEDIA_ERR_SRC_NOT_SUPPORTED</code>.</p></li>
<li><p>Set the element's <code
title="dom-media-networkState">networkState</code> attribute to
the <span
title="dom-media-NETWORK_NO_SOURCE">NETWORK_NO_SOURCE</span>
value.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-error">error</code>
at the <span>media element</span>.</p></li>
<li><p>Set the element's <span>delaying-the-load-event flag</span>
to false. This stops <span title="delay the load event">delaying
the load event</span>.</p></li>
<li><p>Abort these steps. Until the <code
title="dom-media-load">load()</code> method is invoked or the
<code title="attr-media-src">src</code> attribute is changed, the
element won't attempt to load another resource.</p></li>
<!-- it took its ball and went home, sulking. -->
</ol>
<p>Otherwise, the <code>source</code> elements will be used; run
these substeps:</p>
<ol>
<li>
<p>⌛ Let <var title="">pointer</var> be a position
defined by two adjacent nodes in the <span>media
element</span>'s child list, treating the start of the list
(before the first child in the list, if any) and end of the list
(after the last child in the list, if any) as nodes in their own
right. One node is the node before <var title="">pointer</var>,
and the other node is the node after <var
title="">pointer</var>. Initially, let <var
title="">pointer</var> be the position between the <var
title="">candidate</var> node and the next node, if there are
any, or the end of the list, if it is the last node.</p>
<p>As nodes are inserted and removed into the <span>media
element</span>, <var title="">pointer</var> must be updated as
follows:</p>
<dl>
<dt>If a new node is inserted between the two nodes that
define <var title="">pointer</var></dt>
<dd>Let <var title="">pointer</var> be the point between the
node before <var title="">pointer</var> and the new node. In
other words, insertions at <var title="">pointer</var> go after
<var title="">pointer</var>.</dd>
<dt>If the node before <var title="">pointer</var> is removed</dt>
<dd>Let <var title="">pointer</var> be the point between the
node after <var title="">pointer</var> and the node before the
node after <var title="">pointer</var>. In other words, <var
title="">pointer</var> doesn't move relative to the remaining
nodes.</dd>
<dt>If the node after <var title="">pointer</var> is removed</dt>
<dd>Let <var title="">pointer</var> be the point between the
node before <var title="">pointer</var> and the node after the
node before <var title="">pointer</var>. Just as with the
previous case, <var title="">pointer</var> doesn't move
relative to the remaining nodes.</dd>
</dl>
<p>Other changes don't affect <var title="">pointer</var>.</p>
</li>
<li><p>⌛ <i>Process candidate</i>: If <var
title="">candidate</var> does not have a <code
title="attr-source-src">src</code> attribute, then end the
<span>synchronous section</span>, and jump down to the <i
title="">failed</i> step below.</p></li>
<li><p>⌛ Let <var title="">absolute URL</var> be the
<span>absolute URL</span> that would have resulted from <span
title="resolve a url">resolving</span> the <span>URL</span>
specified by <var title="">candidate</var>'s <code
title="attr-source-src">src</code> attribute's value relative to
the <var title="">candidate</var> when the <code
title="attr-source-src">src</code> attribute was last
changed.</p> <!-- i.e. changing xml:base or <base> after src=""
has no effect -->
<li><p>⌛ If <var title="">absolute URL</var> was not
obtained successfully, then end the <span>synchronous
section</span>, and jump down to the <i title="">failed</i> step
below.</p></li>
<li><p>⌛ If <var title="">candidate</var> has a <code
title="attr-source-type">type</code> attribute whose value, when
parsed as a <span>MIME type</span> (including any codecs
described by the <code title="">codecs</code> parameter),
represents <span>a type that the user agent knows it cannot
render</span>, then end the <span>synchronous section</span>, and
jump down to the <i title="">failed</i> step below.</p></li>
<li><p>⌛ If <var title="">candidate</var> has a <code
title="attr-source-media">media</code> attribute whose value does
not <span title="matches the environment">match the
environment</span> of the <span>default view</span>, then end the
<span>synchronous section</span>, and jump down to the <i
title="">failed</i> step below.</p></li>
<li><p>⌛ Set the <code
title="dom-media-currentSrc">currentSrc</code> attribute to <var
title="">absolute URL</var>.</p></li>
<li><p>End the <span>synchronous section</span>, continuing the
remaining steps asynchronously.</p></li>
<li><p>Run the <span title="concept-media-load-resource">resource
fetch algorithm</span> with <var title="">absolute URL</var>. If
that algorithm returns without aborting <em>this</em> one, then
the load failed.</p></li>
<li><p><i title="">Failed</i>: <span>Queue a task</span> to
<span>fire a simple event</span> named <code
title="event-error">error</code> at the <var
title="">candidate</var> element, in the context of the <span
title="fetch">fetching process</span> that was used to try to
obtain <var title="">candidate</var>'s corresponding <span>media
resource</span> in the <span
title="concept-media-load-resource">resource fetch
algorithm</span>.</p></li>
<li><p>Asynchronously <span>await a stable state</span>. The
<span>synchronous section</span> consists of all the remaining
steps of this algorithm until the algorithm says the
<span>synchronous section</span> has ended. (Steps in <span
title="synchronous section">synchronous sections</span> are
marked with ⌛.)</p></li>
<li><p>⌛ <i title="">Find next candidate</i>: Let <var
title="">candidate</var> be null.</p></li>
<li><p>⌛ <i title="">Search loop</i>: If the node after
<var title="">pointer</var> is the end of the list, then jump to
the <i title="">waiting</i> step below.</p></li>
<li><p>⌛ If the node after <var title="">pointer</var> is
a <code>source</code> element, let <var title="">candidate</var>
be that element.</p></li>
<li><p>⌛ Advance <var title="">pointer</var> so that the
node before <var title="">pointer</var> is now the node that was
after <var title="">pointer</var>, and the node after <var
title="">pointer</var> is the node after the node that used to be
after <var title="">pointer</var>, if any.</p></li>
<li><p>⌛ If <var title="">candidate</var> is null, jump
back to the <i title="">search loop</i> step. Otherwise, jump
back to the <i title="">process candidate</i> step.</p></li>
<li><p>⌛ <i title="">Waiting</i>: Set the element's <code
title="dom-media-networkState">networkState</code> attribute to
the <span
title="dom-media-NETWORK_NO_SOURCE">NETWORK_NO_SOURCE</span>
value.</p></li>
<li><p>⌛ Set the element's <span>delaying-the-load-event
flag</span> to false. This stops <span title="delay the load
event">delaying the load event</span>.</p></li>
<li><p>End the <span>synchronous section</span>, continuing the
remaining steps asynchronously.</p></li>
<li><p>Wait until the node after <var title="">pointer</var> is a
node other than the end of the list. (This step might wait
forever.)</p></li>
<li><p>Asynchronously <span>await a stable state</span>. The
<span>synchronous section</span> consists of all the remaining
steps of this algorithm until the algorithm says the
<span>synchronous section</span> has ended. (Steps in <span
title="synchronous section">synchronous sections</span> are
marked with ⌛.)</p></li>
<li><p>⌛ Set the element's <span>delaying-the-load-event
flag</span> back to true (this <span title="delay the load
event">delays the load event</span> again, in case it hasn't been
fired yet).</p>
<li><p>⌛ Set the <code
title="dom-media-networkState">networkState</code> back to <code
title="dom-media-NETWORK_LOADING">NETWORK_LOADING</code>.</p></li>
<li><p>⌛ Jump back to the <i title="">find next
candidate</i> step above.</p></li>
</ol>
</li>
</ol>
<p>The <dfn title="concept-media-load-resource">resource fetch
algorithm</dfn> for a <span>media element</span> and a given
<span>absolute URL</span> is as follows:</p>
<ol>
<li><p>Let the <var title="">current media resource</var> be the
resource given by the <span>absolute URL</span> passed to this
algorithm. This is now the element's <span>media
resource</span>.</p></li>
<li>
<p>Begin to <span>fetch</span> the <var title="">current media
resource</var>, from the <span>media element</span>'s
<code>Document</code>'s <span>origin</span>.</p> <!-- not
http-origin privacy sensitive (looking forward to CORS here) -->
<p>Every 350ms (±200ms) or for every byte received, whichever
is <em>least</em> frequent, <span>queue a task</span> to
<span>fire a simple event</span> named <code
title="event-media-progress">progress</code> at the element.</p>
<p>If at any point the user agent has received no data for more
than about three seconds, then <span>queue a task</span> to
<span>fire a simple event</span> named <code
title="event-media-stalled">stalled</code> at the element.</p>
<p>User agents may allow users to selectively block or slow
<span>media data</span> downloads. When a <span>media
element</span>'s download has been blocked altogether, the user
agent must act as if it was stalled (as opposed to acting as if
the connection was closed). The rate of the download may also be
throttled automatically by the user agent, e.g. to balance the
download with other connections sharing the same bandwidth.</p>
<p>User agents may decide to not download more content at any
time, e.g. after buffering five minutes of a one hour media
resource, while waiting for the user to decide whether to play the
resource or not, or while waiting for user input in an interactive
resource. When a <span>media element</span>'s download has been
suspended, the user agent must set the <code
title="dom-media-networkState">networkState</code> to <code
title="dom-media-NETWORK_IDLE">NETWORK_IDLE</code> and <span>queue
a task</span> to <span>fire a simple event</span> named <code
title="event-media-suspend">suspend</code> at the element. If and
when downloading of the resource resumes, the user agent must set
the <code title="dom-media-networkState">networkState</code> to
<code
title="dom-media-NETWORK_LOADING">NETWORK_LOADING</code>.</p>
<p>The <code title="attr-media-autobuffer">autobuffer</code>
attribute provides a hint that the author expects that downloading
the entire resource optimistically will be worth it, even in the
absence of the <code title="attr-media-autoplay">autoplay</code>
attribute. In the absence of either attribute, the user agent is
likely to find that waiting until the user starts playback before
downloading any further content leads to a more efficient use of
the network resources.</p>
<p>When a user agent decides to completely stall a download,
e.g. if it is waiting until the user starts playback before
downloading any further content, the element's
<span>delaying-the-load-event flag</span> must be set to
false. This stops <span title="delay the load event">delaying the
load event</span>.</p>
<p>The user agent may use whatever means necessary to fetch the
resource (within the constraints put forward by this and other
specifications); for example, reconnecting to the server in the
face of network errors, using HTTP range retrieval requests, or
switching to a streaming protocol. The user agent must consider a
resource erroneous only if it has given up trying to fetch it.</p>
<p>The <span>networking task source</span> <span
title="concept-task">tasks</span> to process the data as it is
being fetched must, when appropriate, include the relevant
substeps from the following list:</p>
<dl class="switch">
<dt>If the <span>media data</span> cannot be fetched at all, due
to network errors, causing the user agent to give up trying to
fetch the resource</dt>
<dt>If the <span>media resource</span> is found to have <span
title="Content-Type">Content-Type metadata</span> that, when
parsed as a <span>MIME type</span> (including any codecs described by the
<code title="">codecs</code> parameter), represents <span>a type
that the user agent knows it cannot render</span> (even if the
actual <span>media data</span> is in a supported format)</dt>
<dt>If the <span>media data</span> can be fetched but is found by
inspection to be in an unsupported format, or can otherwise not
be rendered at all</dt>
<dd>
<p>DNS errors, HTTP 4xx and 5xx errors (and equivalents in
other protocols), and other fatal network errors that occur
before the user agent has established whether the <var
title="">current media resource</var> is usable, as well as
the file using an unsupported container format, or using
unsupported codecs for all the data, must cause the user agent
to execute the following steps:</p>
<ol>
<li><p>The user agent should cancel the fetching
process.</p></li>
<li><p>Abort this subalgorithm, returning to the <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</p>
</ol>
</dd>
<!-- insert content sniffing here if we want to define that -->
<!-- (in practice I don't think that's necessary since it's not
like you can do anything with the resource if you sniff it as the
wrong type) -->
<dt id="getting-media-metadata">Once enough of the <span>media
data</span> has been fetched to determine the duration of the
<span>media resource</span>, its dimensions, and other
metadata</dt>
<dd>
<p>This indicates that the resource is usable. The user agent
must follow these substeps:</p>
<ol>
<li><p>Set the <span>current playback position</span> to the
<span>earliest possible position</span>.</p></li>
<li><p>Set the <code
title="dom-media-readyState">readyState</code> attribute to
<code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code>.</p></li>
<li><p>For <code>video</code> elements, set the <code
title="dom-video-videoWidth">videoWidth</code> and <code
title="dom-video-videoHeight">videoHeight</code>
attributes.</p></li>
<li>
<p>Set the <code title="dom-media-duration">duration</code>
attribute to the duration of the resource.</p>
<p class="note">The user agent <a
href="#durationChange">will</a> <span>queue a task</span> to
<span>fire a simple event</span> named <code
title="event-media-durationchange">durationchange</code> at the
element at this point.</p>
</li>
<li id="fire-loadedmetadata">
<p><span>Queue a task</span> to <span>fire a simple
event</span> named <code
title="event-media-loadedmetadata">loadedmetadata</code> at the
element.</p>
<p class="note">Before this task is run, as part of the event
loop mechanism, the rendering will have been updated to resize
the <code>video</code> element if appropriate.</p>
</li>
<li>
<p>If either the <span>media resource</span> or the address
of the <var title="">current media resource</var> indicate a
particular start time, then <span
title="dom-media-seek">seek</span> to that time. Ignore any
resulting exceptions (if the position is out of range, it is
effectively ignored).</p>
<p class="example">For example, a fragment identifier could be
used to indicate a start position.</p>
</li>
<li>
<p>Once the <code
title="dom-media-readyState">readyState</code> attribute
reaches <code
title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code>,
<a href="#fire-loadeddata">after the <code
title="event-media-loadeddata">loadeddata</code> event has been
fired</a>, set the element's <span>delaying-the-load-event
flag</span> to false. This stops <span title="delay the load
event">delaying the load event</span>.</p>
<p class="note">A user agent that is attempting to reduce
network usage while still fetching the metadata for each
<span>media resource</span> would also stop buffering at this
point, causing the <code
title="dom-media-networkState">networkState</code> attribute
to switch to the <code
title="dom-media-NETWORK_IDLE">NETWORK_IDLE</code> value, if
the <span>media element</span> did not have an <code
title="attr-media-autobuffer">autobuffer</code> or <code
title="attr-media-autoplay">autoplay</code> attribute.</p>
</li>
</ol>
<p class="note">The user agent is <em>required</em> to
determine the duration of the <span>media resource</span> and
go through this step before playing.</p> <!-- actually defined
in the 'duration' section -->
</dd>
<dt>Once the entire <span>media resource</span> has been <span
title="fetch">fetched</span> (but potentially before any of it
has been decoded)</dt>
<dd>
<p><span>Queue a task</span> to <span>fire a simple event</span>
named <code title="event-media-progress">progress</code> at the
<span>media element</span>.</p>
</dd>
<dt>If the connection is interrupted, causing the user agent to
give up trying to fetch the resource</dt>
<dd>
<p>Fatal network errors that occur after the user agent has
established whether the <var title="">current media
resource</var> is usable must cause the user agent to execute
the following steps:</p>
<ol>
<li><p>The user agent should cancel the fetching
process.</p></li>
<li><p>Set the <code title="dom-media-error">error</code>
attribute to a new <code>MediaError</code> object whose <code
title="dom-MediaError-code">code</code> attribute is set to
<code
title="dom-MediaError-MEDIA_ERR_NETWORK">MEDIA_ERR_NETWORK</code>.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-error">error</code>
at the <span>media element</span>.</p></li>
<li><p>Set the element's <code
title="dom-media-networkState">networkState</code> attribute to
the <span title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</span>
value and <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-emptied">emptied</code>
at the element.</p></li>
<li><p>Set the element's <span>delaying-the-load-event
flag</span> to false. This stops <span title="delay the load
event">delaying the load event</span>.</p></li>
<li><p>Abort the overall <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</p></li>
</ol>
</dd>
<dt id="fatal-decode-error">If the <span>media data</span> is
corrupted</dt>
<dd>
<p>Fatal errors in decoding the <span>media data</span> that
occur after the user agent has established whether the <var
title="">current media resource</var> is usable must cause the
user agent to execute the following steps:</p>
<ol>
<li><p>The user agent should cancel the fetching
process.</p></li>
<li><p>Set the <code title="dom-media-error">error</code>
attribute to a new <code>MediaError</code> object whose <code
title="dom-MediaError-code">code</code> attribute is set to
<code
title="dom-MediaError-MEDIA_ERR_DECODE">MEDIA_ERR_DECODE</code>.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-error">error</code>
at the <span>media element</span>.</p></li>
<li><p>Set the element's <code
title="dom-media-networkState">networkState</code> attribute to
the <span title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</span>
value and <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-emptied">emptied</code>
at the element.</p></li>
<li><p>Set the element's <span>delaying-the-load-event
flag</span> to false. This stops <span title="delay the load
event">delaying the load event</span>.</p></li>
<li><p>Abort the overall <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</p></li>
</ol>
</dd>
<dt>If the <span>media data</span> fetching process is aborted by
the user</dt>
<dd>
<p>The fetching process is aborted by the user, e.g. because the
user navigated the browsing context to another page, the user
agent must execute the following steps. These steps are not
followed if the <code title="dom-media-load">load()</code>
method itself is invoked while these steps are running, as the
steps above handle that particular kind of abort.</p>
<ol>
<li><p>The user agent should cancel the fetching
process.</p></li>
<li><p>Set the <code title="dom-media-error">error</code>
attribute to a new <code>MediaError</code> object whose <code
title="dom-MediaError-code">code</code> attribute is set to
<code
title="dom-MediaError-MEDIA_ERR_ABORT">MEDIA_ERR_ABORT</code>.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-abort">abort</code>
at the <span>media element</span>.</p></li>
<li><p>If the <span>media element</span>'s <code
title="dom-media-readyState">readyState</code> attribute has a
value equal to <code
title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code>, set the
element's <code
title="dom-media-networkState">networkState</code> attribute to
the <span title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</span>
value and <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-emptied">emptied</code>
at the element. Otherwise, set the element's <code
title="dom-media-networkState">networkState</code> attribute to
the <span title="dom-media-NETWORK_IDLE">NETWORK_IDLE</span>
value.</p></li>
<li><p>Set the element's <span>delaying-the-load-event
flag</span> to false. This stops <span title="delay the load
event">delaying the load event</span>.</p></li>
<li><p>Abort the overall <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</p></li>
</ol>
</dd>
<dt id="non-fatal-media-error">If the <span>media data</span> can
be fetched but has non-fatal errors or uses, in part, codecs that
are unsupported, preventing the user agent from rendering the
content completely correctly but not preventing playback
altogether</dt>
<dd>
<p>The server returning data that is partially usable but cannot
be optimally rendered must cause the user agent to render just
the bits it can handle, and ignore the rest.</p>
<!-- v2: fire a 'warning' event and set the 'error' flag to 'MEDIA_ERR_SUBOPTIMAL' or something -->
</dd>
</dl>
<p>When the <span>networking task source</span> has <span
title="queue a task">queued</span> the last <span
title="concept-task">task</span> as part of <span
title="fetch">fetching</span> the <span>media resource</span>
(i.e. once the download has completed), if the fetching process
completes without errors, including decoding the media data, and
if all of the data is available to the user agent without network
access, then, the user agent must move on to the next step. This
might never happen, e.g. when streaming an infinite resource such
as Web radio, or if the resource is longer than the user agent's
ability to cache data.</p>
<p>While the user agent might still need network access to obtain
parts of the <span>media resource</span>, the user agent must
remain on this step.</p>
<p class="example">For example, if the user agent has discarded
the first half of a video, the user agent will remain at this step
even once the <span title="ended playback">playback has
ended</span>, because there is always the chance the user will
seek back to the start. In fact, in this situation, once <span
title="ended playback">playback has ended</span>, the user agent
will end up dispatching a <code
title="event-media-stalled">stalled</code> event, as described
earlier.</p>
</li>
<li><p>If the user agent ever reaches this step (which can only
happen if the entire resource gets loaded and kept available):
abort the overall <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</p></li>
</ol>
</div>
<p>The <dfn
title="attr-media-autobuffer"><code>autobuffer</code></dfn>
attribute is a <span>boolean attribute</span>. Its presence hints to
the user agent that the author believes that the <span>media
element</span> will likely be used, even though the element does not
have an <code title="attr-media-autoplay">autoplay</code>
attribute. (The attribute has no effect if used in conjunction with
the <code title="attr-media-autoplay">autoplay</code> attribute,
though including both is not an error.) <span class="impl">This
attribute may be ignored altogether. The attribute must be ignored
if the <code title="attr-media-autoplay">autoplay</code> attribute
is present.</span></p>
<div class="impl">
<p>The <dfn
title="dom-media-autobuffer"><code>autobuffer</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name.</p>
</div>
<!--v3BUF (when readding this, also add a domintro block)
<p>The <dfn
title="dom-media-bufferingRate"><code>bufferingRate</code></dfn>
attribute must return the average number of bits received per second
for the current download over the past few seconds. If there is no
download in progress, the attribute must return 0.</p>
<p>The <dfn
title="dom-media-bufferingThrottled"><code>bufferingThrottled</code></dfn>
attribute must return true if the user agent is intentionally
throttling the bandwidth used by the download (including when
throttling to zero to pause the download altogether), and false
otherwise.</p>
-->
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-buffered">buffered</code></dt>
<dd>
<p>Returns a <code>TimeRanges</code> object that represents the
ranges of the <span>media resource</span> that the user agent has
buffered.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-media-buffered"><code>buffered</code></dfn>
attribute must return a new static <span>normalized
<code>TimeRanges</code> object</span> that represents the ranges of
the <span>media resource</span>, if any, that the user agent has
buffered, at the time the attribute is evaluated. Users agents must
accurately determine the ranges available, even for media streams
where this can only be determined by tedious inspection.</p>
<p class="note">Typically this will be a single range anchored at
the zero point, but if, e.g. the user agent uses HTTP range requests
in response to seeking, then there could be multiple ranges.</p>
<p>User agents may discard previously buffered data.</p>
<p class="note">Thus, a time position included within a range of the
objects return by the <code
title="dom-media-buffered">buffered</code> attribute at one time can
end up being not included in the range(s) of objects returned by the
same attribute at later times.</p>
</div>
<h5>Offsets into the media resource</h5>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-duration">duration</code></dt>
<dd>
<p>Returns the length of the <span>media resource</span>, in
seconds.</p>
<p>Returns NaN if the duration isn't available.<p>
<p>Returns Infinity for unbounded streams.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-currentTime">currentTime</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the <span>current playback position</span>, in seconds.</p>
<p>Can be set, to seek to the given time.<p>
<p>Will throw an <code>INVALID_STATE_ERR</code> exception if there
is no selected <span>media resource</span>. Will throw an
<code>INDEX_SIZE_ERR</code> exception if the given time is not
within the ranges to which the user agent can seek.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-startTime">startTime</code></dt>
<dd>
<p>Returns the <span>earliest possible position</span>, in
seconds. This is the time for the start of the current clip. It
might not be zero if the clip's timeline is not zero-based, or if
the resource is a streaming resource (in which case it gives the
earliest time that the user agent is able to seek back to).</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-media-duration"><code>duration</code></dfn>
attribute must return the length of the <span>media resource</span>,
in seconds. If no <span>media data</span> is available, then the
attributes must return the Not-a-Number (NaN) value. If the
<span>media resource</span> is known to be unbounded (e.g. a
streaming radio), then the attribute must return the positive
Infinity value.</p>
<p>The user agent must determine the duration of the <span>media
resource</span> before playing any part of the <span>media
data</span> and before setting <code
title="dom-media-readyState">readyState</code> to a value equal to
or greater than <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code>, even if doing
so requires seeking to multiple parts of the resource.</p>
<p id="durationChange">When the length of the <span>media
resource</span> changes (e.g. from being unknown to known, or from a
previously established length to a new length) the user agent must
<span>queue a task</span> to <span>fire a simple event</span> named
<code title="event-media-durationchange">durationchange</code> at the
<span>media element</span>.</p>
<p class="example">If an "infinite" stream ends for some reason,
then the duration would change from positive Infinity to the time of
the last frame or sample in the stream, and the <code
title="event-media-durationchange">durationchange</code> event would be
fired. Similarly, if the user agent initially estimated the
<span>media resource</span>'s duration instead of determining it
precisely, and later revises the estimate based on new information,
then the duration would change and the <code
title="event-media-durationchange">durationchange</code> event would be
fired.</p>
<p><span title="media element">Media elements</span> have a
<dfn>current playback position</dfn>, which must initially be
zero. The current position is a time.</p>
<p>The <dfn
title="dom-media-currentTime"><code>currentTime</code></dfn>
attribute must, on getting, return the <span>current playback
position</span>, expressed in seconds. On setting, the user agent
must <span title="dom-media-seek">seek</span> to the new value
(which might raise an exception).</p>
<p>If the <span>media resource</span> is a streaming resource, then
the user agent might be unable to obtain certain parts of the
resource after it has expired from its buffer. Similarly, some <span
title="media resource">media resources</span> might have a timeline
that doesn't start at zero. The <dfn>earliest possible
position</dfn> is the earliest position in the stream or resource
that the user agent can ever obtain again.</p>
<p>The <dfn title="dom-media-startTime"><code>startTime</code></dfn>
attribute must, on getting, return the <span>earliest possible
position</span>, expressed in seconds.</p>
<p>When the <span>earliest possible position</span> changes, then:
if the <span>current playback position</span> is before the
<span>earliest possible position</span>, the user agent must <span
title="dom-media-seek">seek</span> to the <span>earliest possible
position</span>; otherwise, if the user agent has not fired a <code
title="event-media-timeupdate">timeupdate</code> event at the element in
the past 15 to 250ms, then the user agent must <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-media-timeupdate">timeupdate</code> at the element.</p>
<p class="note">Because of the above requirement and the requirement
in the <span title="concept-media-load-resource">resource fetch
algorithm</span> that kicks in <a
href="#getting-media-metadata">when the metadata of the clip becomes
known</a>, the <span>current playback position</span> can never be
less than the <span>earliest possible position</span>.</p>
<p>User agents must act as if the timeline of the <span>media
resource</span> increases linearly starting from the <span>earliest
possible position</span>, even if the underlying <span>media
data</span> has out-of-order or even overlapping time codes.</p>
<p class="example">For example, if two clips have been concatenated
into one video file, but the video format exposes the original times
for the two clips, the video data might expose a timeline that goes,
say, 00:15..00:29 and then 00:05..00:38. However, the user agent
would not expose those times; it would instead expose the times as
00:15..00:29 and 00:29..01:02, as a single video.</p>
</div>
<p>The <dfn title="attr-media-loop"><code>loop</code></dfn>
attribute is a <span>boolean attribute</span> that, if specified,
indicates that the <span>media element</span> is to seek back to the
start of the <span>media resource</span> upon reaching the end.</p>
<div class="impl">
<p>The <dfn title="dom-media-loop"><code>loop</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name.</p>
</div>
<h5>The ready states</h5>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-readyState">readyState</code></dt>
<dd>
<p>Returns a value that expresses the current state of the element
with respect to rendering the <span>current playback
position</span>, from the codes in the list below.</p>
</dd>
</dl>
<div class="impl">
<p><span title="media element">Media elements</span> have a
<i>ready state</i>, which describes to what degree they are ready
to be rendered at the <span>current playback position</span>. The
possible values are as follows; the ready state of a media element
at any particular time is the greatest value describing the state of
the element:</p>
</div>
<dl>
<dt><dfn title="dom-media-HAVE_NOTHING"><code>HAVE_NOTHING</code></dfn> (numeric value 0)</dt>
<dd>No information regarding the <span>media resource</span> is
available. No data for the <span>current playback position</span>
is available. <span title="media element">Media elements</span>
whose <code title="dom-media-networkState">networkState</code>
attribute is <code
title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code> are always in
the <code title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code>
state.</dd>
<dt><dfn title="dom-media-HAVE_METADATA"><code>HAVE_METADATA</code></dfn> (numeric value 1)</dt>
<dd>Enough of the resource has been obtained that the duration of
the resource is available. In the case of a <code>video</code>
element, the dimensions of the video are also available. The API
will no longer raise an exception when seeking. No <span>media
data</span> is available for the immediate <span>current playback
position</span>.</dd>
<dt><dfn title="dom-media-HAVE_CURRENT_DATA"><code>HAVE_CURRENT_DATA</code></dfn> (numeric value 2)</dt>
<dd>Data for the immediate <span>current playback position</span>
is available, but either not enough data is available that the user
agent could successfully advance the <span>current playback
position</span> in the <span>direction of playback</span> at all
without immediately reverting to the <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code> state, or
there is no more data to obtain in the <span>direction of
playback</span>. For example, in video this corresponds to the user
agent having data from the current frame, but not the next frame;
and to when <span title="ended playback">playback has
ended</span>.</dd>
<dt><dfn title="dom-media-HAVE_FUTURE_DATA"><code>HAVE_FUTURE_DATA</code></dfn> (numeric value 3)</dt>
<dd>Data for the immediate <span>current playback position</span>
is available, as well as enough data for the user agent to advance
the <span>current playback position</span> in the <span>direction
of playback</span> at least a little without immediately reverting
to the <code title="dom-media-HAVE_METADATA">HAVE_METADATA</code>
state. For example, in video this corresponds to the user agent
having data for at least the current frame and the next frame. The
user agent cannot be in this state if <span title="ended
playback">playback has ended</span>, as the <span>current playback
position</span> can never advance in this case.</dd>
<dt><dfn title="dom-media-HAVE_ENOUGH_DATA"><code>HAVE_ENOUGH_DATA</code></dfn> (numeric value 4)</dt>
<dd>All the conditions described for the <code
title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code> state
are met, and, in addition, the user agent estimates that data is
being fetched at a rate where the <span>current playback
position</span>, if it were to advance at the rate given by the
<code
title="dom-media-defaultPlaybackRate">defaultPlaybackRate</code>
attribute, would not overtake the available data before playback
reaches the end of the <span>media resource</span>.</dd>
</dl>
<div class="impl">
<p>When the ready state of a <span>media element</span> whose <code
title="dom-media-networkState">networkState</code> is not <code
title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code> changes, the
user agent must follow the steps given below:</p>
<dl class="switch">
<!-- going up to metadata -->
<dt>If the previous ready state was <code
title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code>, and the new
ready state is <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code></dt>
<dd>
<p class="note">A <code
title="event-media-loadedmetadata">loadedmetadata</code> DOM event <a
href="#fire-loadedmetadata">will be fired</a> as part of the <code
title="dom-media-load">load()</code> algorithm.</p>
</dd>
<!-- going up to current for the first time -->
<dt id="handling-first-frame-available">If the previous ready state
was <code title="dom-media-HAVE_METADATA">HAVE_METADATA</code> and
the new ready state is <code
title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code> or
greater</dt>
<dd>
<p id="fire-loadeddata">If this is the first time this occurs for
this <span>media element</span> since the <code
title="dom-media-load">load()</code> algorithm was last invoked,
the user agent must <span>queue a task</span> to <span>fire a
simple event</span> named <code
title="event-media-loadeddata">loadeddata</code> at the element.</p>
<p>If the new ready state is <code
title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code> or
<code title="dom-media-HAVE_ENOUGH_DATA">HAVE_ENOUGH_DATA</code>,
then the relevant steps below must then be run also.</p>
</dd>
<!-- going down -->
<dt>If the previous ready state was <code
title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code> or more,
and the new ready state is <code
title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code> or
less</dt>
<dd>
<p class="note">A <code title="event-media-waiting">waiting</code> DOM
event <a href="#fire-waiting-when-waiting">can be fired</a>,
depending on the current state of playback.</p>
</dd>
<!-- going up to future -->
<dt>If the previous ready state was <code
title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code> or
less, and the new ready state is <code
title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code></dt>
<dd>
<p>The user agent must <span>queue a task</span> to <span>fire a
simple event</span> named <code
title="event-media-canplay">canplay</code>.</p>
<p>If the element is <span>potentially playing</span>, the user
agent must <span>queue a task</span> to <span>fire a simple
event</span> named <code
title="event-media-playing">playing</code>.</p>
</dd>
<!-- going up to enough -->
<dt>If the new ready state is <code
title="dom-media-HAVE_ENOUGH_DATA">HAVE_ENOUGH_DATA</code></dt>
<dd>
<p>If the previous ready state was <code
title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code> or
less, the user agent must <span>queue a task</span> to <span>fire
a simple event</span> named <code
title="event-media-canplay">canplay</code>, and, if the element is also
<span>potentially playing</span>, <span>queue a task</span> to
<span>fire a simple event</span> named <code
title="event-media-playing">playing</code>.</p>
<p>If the <span>autoplaying flag</span> is true, and the <code
title="dom-media-paused">paused</code> attribute is true, and the
<span>media element</span> has an <code
title="attr-media-autoplay">autoplay</code> attribute specified,
then the user agent may also set the <code
title="dom-media-paused">paused</code> attribute to false,
<span>queue a task</span> to <span>fire a simple event</span>
named <code title="event-media-play">play</code>, and <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-media-playing">playing</code>.</p>
<p class="note">User agents are not required to autoplay, and it
is suggested that user agents honor user preferences on the
matter. Authors are urged to use the <code
title="attr-media-autoplay">autoplay</code> attribute rather than
using script to force the video to play, so as to allow the user
to override the behavior if so desired.</p>
<p>In any case, the user agent must finally <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-media-canplaythrough">canplaythrough</code>.</p>
</dd>
</dl>
</div>
<p class="note">It is possible for the ready state of a media
element to jump between these states discontinuously. For example,
the state of a media element can jump straight from <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code> to <code
title="dom-media-HAVE_ENOUGH_DATA">HAVE_ENOUGH_DATA</code> without
passing through the <code
title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code> and
<code title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code>
states.</p>
<div class="impl">
<p>The <dfn
title="dom-media-readyState"><code>readyState</code></dfn> IDL
attribute must, on getting, return the value described above that
describes the current ready state of the <span>media
element</span>.</p>
</div>
<p>The <dfn title="attr-media-autoplay"><code>autoplay</code></dfn>
attribute is a <span>boolean attribute</span>. When present, the
user agent <span class="impl">(as described in the algorithm
described herein)</span> will automatically begin playback of the
<span>media resource</span> as soon as it can do so without
stopping.</p>
<p class="note">Authors are urged to use the <code
title="attr-media-autoplay">autoplay</code> attribute rather than
using script to trigger automatic playback, as this allows the user
to override the automatic playback when it is not desired, e.g. when
using a screen reader. Authors are also encouraged to consider not
using the automatic playback behavior at all, and instead to let the
user agent wait for the user to start playback explicitly.</p>
<div class="impl">
<p>The <dfn title="dom-media-autoplay"><code>autoplay</code></dfn>
IDL attribute must <span>reflect</span> the content attribute of the
same name.</p>
</div>
<!--v2CUERANGE
<h5>Cue ranges</h5>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-addCueRange">addCueRange</code>(<var title="">className</var>, <var title="">id</var>, <var title="">start</var>, <var title="">end</var>, <var title="">pauseOnExit</var>, <var title="">enterCallback</var>, <var title="">exitCallback</var>)</dt>
<dd>
<p>Registers a range of time, given in seconds, and a pair of
callbacks, the first of which will be invoked when the
<span>current playback position</span> enters the range, and the
second of which will be invoked when it exits the range. The
callbacks are invoked with the given ID as their argument.</p>
<p>In addition, if the <var title="">pauseOnExit</var> argument is
true, then playback will pause when it reaches the end of the
range.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-removeCueRange">removeCueRange</code>(<var title="">className</var>)</dt>
<dd>
<p>Removes all the ranges that were registered with the given
class name.</p>
</dd>
</dl>
<div class="impl">
<p><span title="media element">Media elements</span> have a set of
<dfn title="cue range">cue ranges</dfn>. Each cue range is made up
of the following information:</p>
<dl>
<dt>A class name</dt>
<dd>A group of related ranges can be given the same class name so
that they can all be removed at the same time.</dd>
<dt>An identifier</dt>
<dd>A string can be assigned to each cue range for identification
by script. The string need not be unique and can contain any
value.</dd>
<dt>A start time</dt>
<dt>An end time</dt>
<dd>The actual time range, using the same timeline as the
<span>media resource</span> itself.</dd>
<dt>A "pause" boolean</dt>
<dd>A flag indicating whether to pause playback on exit.</dd>
<dt>An "enter" callback</dt>
<dd>A callback that is called when the <span>current playback
position</span> enters the range.</dd>
<dt>An "exit" callback</dt>
<dd>A callback that is called when the <span>current playback
position</span> exits the range.</dd>
<dt>An "active" boolean</dt>
<dd>A flag indicating whether the range is active or not.</dd>
</dl>
<p>The <dfn title="dom-media-addCueRange"><code>addCueRange(<var
title="">className</var>, <var title="">id</var>, <var
title="">start</var>, <var title="">end</var>, <var
title="">pauseOnExit</var>, <var title="">enterCallback</var>, <var
title="">exitCallback</var>)</code></dfn> method must, when called,
add a <span>cue range</span> to the <span>media element</span>, that
cue range having the class name <var title="">className</var>, the
identifier <var title="">id</var>, the start time <var
title="">start</var> (in seconds), the end time <var
title="">end</var> (in seconds), the "pause" boolean with the same
value as <var title="">pauseOnExit</var>, the "enter" callback <var
title="">enterCallback</var>, the "exit" callback <var
title="">exitCallback</var>, and an "active" boolean that is true if
the <span>current playback position</span> is equal to or greater
than the start time and less than the end time, and false
otherwise.</p>
<p>The <dfn
title="dom-media-removeCueRanges"><code>removeCueRanges(<var
title="">className</var>)</code></dfn> method must, when called,
remove all the <span title="cue range">cue ranges</span> of the
<span>media element</span> which have the class name <var
title="">className</var>.</p>
</div>
-->
<h5>Playing the media resource</h5>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-paused">paused</code></dt>
<dd>
<p>Returns true if playback is paused; false otherwise.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-ended">ended</code></dt>
<dd>
<p>Returns true if playback has reached the end of the <span>media resource</span>.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-defaultPlaybackRate">defaultPlaybackRate</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the default rate of playback, for when the user is not
fast-forwarding or reversing through the <span>media
resource</span>.</p>
<p>Can be set, to change the default rate of playback.</p>
<p>The default rate has no direct effect on playback, but if the
user switches to a fast-forward mode, when they return to the
normal playback mode, it is expected that the rate of playback
will be returned to the default rate of playback.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-playbackRate">playbackRate</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current rate playback, where 1.0 is normal speed.</p>
<p>Can be set, to change the rate of playback.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-played">played</code></dt>
<dd>
<p>Returns a <code>TimeRanges</code> object that represents the
ranges of the <span>media resource</span> that the user agent has
played.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-play">play</code>()</dt>
<dd>
<p>Sets the <code title="dom-media-paused">paused</code> attribute
to false, loading the <span>media resource</span> and beginning
playback if necessary. If the playback had ended, will restart it
from the start.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-pause">pause</code>()</dt>
<dd>
<p>Sets the <code title="dom-media-paused">paused</code> attribute
to true, loading the <span>media resource</span> if necessary.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-media-paused"><code>paused</code></dfn>
attribute represents whether the <span>media element</span> is
paused or not. The attribute must initially be true.</p>
<p>A <span>media element</span> is said to be <dfn>potentially
playing</dfn> when its <code title="dom-media-paused">paused</code>
attribute is false, the <code
title="dom-media-readyState">readyState</code> attribute is either
<code title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code> or
<code title="dom-media-HAVE_ENOUGH_DATA">HAVE_ENOUGH_DATA</code>,
the element has not <span>ended playback</span>, playback has not
<span>stopped due to errors</span>, and the element has not
<span>paused for user interaction</span>.</p>
<p>A <span>media element</span> is said to have <dfn>ended
playback</dfn> when the element's <code
title="dom-media-readyState">readyState</code> attribute is <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code> or greater, and
either the <span>current playback position</span> is the end of the
<span>media resource</span> and the <span>direction of
playback</span> is forwards and the <span>media element</span> does
not have a <code title="attr-media-loop">loop</code> attribute
specified, or the <span>current playback position</span> is the
<span>earliest possible position</span> and the <span>direction of
playback</span> is backwards.</p>
<p>The <dfn title="dom-media-ended"><code>ended</code></dfn>
attribute must return true if the <span>media element</span> has
<span>ended playback</span> and the <span>direction of
playback</span> is forwards, and false otherwise.</p>
<p>A <span>media element</span> is said to have <dfn>stopped due to
errors</dfn> when the element's <code
title="dom-media-readyState">readyState</code> attribute is <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code> or greater, and
the user agent <a href="#non-fatal-media-error">encounters a
non-fatal error</a> during the processing of the <span>media
data</span>, and due to that error, is not able to play the content
at the <span>current playback position</span>.</p>
<p>A <span>media element</span> is said to have <dfn>paused for user
interaction</dfn> when its <code
title="dom-media-paused">paused</code> attribute is false, the <code
title="dom-media-readyState">readyState</code> attribute is either
<code title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code> or
<code title="dom-media-HAVE_ENOUGH_DATA">HAVE_ENOUGH_DATA</code> and
the user agent has reached a point in the <span>media
resource</span> where the user has to make a selection for the
resource to continue.</p>
<p>It is possible for a <span>media element</span> to have both
<span>ended playback</span> and <span>paused for user
interaction</span> at the same time.</p>
<p>When a <span>media element</span> that is <span>potentially
playing</span> stops playing because it has <span>paused for user
interaction</span>, the user agent must <span>queue a task</span> to
<span>fire a simple event</span> named <code
title="event-media-timeupdate">timeupdate</code> at the element.</p>
<p id="fire-waiting-when-waiting">When a <span>media element</span>
that is <span>potentially playing</span> stops playing because its
<code title="dom-media-readyState">readyState</code> attribute
changes to a value lower than <code
title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code>, without
the element having <span>ended playback</span>, or playback having
<span>stopped due to errors</span>, or playback having <span>paused
for user interaction</span>, or the <span
title="dom-media-seek">seeking algorithm</span> being invoked, the
user agent must <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-timeupdate">timeupdate</code>
at the element, and <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-waiting">waiting</code> at
the element.</p>
<p>When the <span>current playback position</span> reaches the end
of the <span>media resource</span> when the <span>direction of
playback</span> is forwards, then the user agent must follow these
steps:</p>
<ol>
<li><p>If the <span>media element</span> has a <code
title="attr-media-loop">loop</code> attribute specified, then <span
title="dom-media-seek">seek</span> to the <span>earliest possible
position</span> of the <span>media resource</span> and abort these
steps.</p></li> <!-- v2/v3: We should fire a 'looping' event here
to explain why this immediately fires a 'playing' event, otherwise
the 'playing' event that fires from the readyState going from
HAVE_CURRENT_DATA back to HAVE_FUTURE_DATA will seem inexplicable
(since the normally matching 'ended' given below event doesn't fire
in the loop case). -->
<li><p>Stop playback.</p><p class="note">The <code
title="dom-media-ended">ended</code> attribute becomes
true.</p></li>
<li><p>The user agent must <span>queue a task</span> to <span>fire
a simple event</span> named <code
title="event-media-timeupdate">timeupdate</code> at the element.</p></li>
<li><p>The user agent must <span>queue a task</span> to <span>fire
a simple event</span> named <code title="event-media-ended">ended</code>
at the element.</p></li>
</ol>
<p>When the <span>current playback position</span> reaches the
<span>earliest possible position</span> of the <span>media
resource</span> when the <span>direction of playback</span> is
backwards, then the user agent must follow these steps:</p>
<ol>
<li><p>Stop playback.</p></li>
<li><p>The user agent must <span>queue a task</span> to <span>fire
a simple event</span> named <code
title="event-media-timeupdate">timeupdate</code> at the element.</p></li>
</ol>
<p>The <dfn
title="dom-media-defaultPlaybackRate"><code>defaultPlaybackRate</code></dfn>
attribute gives the desired speed at which the <span>media
resource</span> is to play, as a multiple of its intrinsic
speed. The attribute is mutable: on getting it must return the last
value it was set to, or 1.0 if it hasn't yet been set; on setting
the attribute must be set to the new value.</p>
<p>The <dfn
title="dom-media-playbackRate"><code>playbackRate</code></dfn>
attribute gives the speed at which the <span>media resource</span>
plays, as a multiple of its intrinsic speed. If it is not equal to
the <code
title="dom-media-defaultPlaybackRate">defaultPlaybackRate</code>,
then the implication is that the user is using a feature such as
fast forward or slow motion playback. The attribute is mutable: on
getting it must return the last value it was set to, or 1.0 if it
hasn't yet been set; on setting the attribute must be set to the new
value, and the playback must change speed (if the element is
<span>potentially playing</span>).</p>
<p>If the <code title="dom-media-playbackRate">playbackRate</code>
is positive or zero, then the <dfn>direction of playback</dfn> is
forwards. Otherwise, it is backwards.</p>
<p>The "play" function in a user agent's interface must set the
<code title="dom-media-playbackRate">playbackRate</code> attribute
to the value of the <code
title="dom-media-defaultPlaybackRate">defaultPlaybackRate</code>
attribute before invoking the <code
title="dom-media-play">play()</code> method's steps. Features such
as fast-forward or rewind must be implemented by only changing the
<code title="dom-media-playbackRate">playbackRate</code>
attribute.</p>
<p id="rateUpdate">When the <code
title="dom-media-defaultPlaybackRate">defaultPlaybackRate</code> or
<code title="dom-media-playbackRate">playbackRate</code> attributes
change value (either by being set by script or by being changed
directly by the user agent, e.g. in response to user control) the
user agent must <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-ratechange">ratechange</code>
at the <span>media element</span>.</p>
<p>The <dfn title="dom-media-played"><code>played</code></dfn>
attribute must return a new static <span>normalized
<code>TimeRanges</code> object</span> that represents the ranges of
the <span>media resource</span>, if any, that the user agent has so
far rendered, at the time the attribute is evaluated.</p>
<hr>
<p>When the <dfn title="dom-media-play"><code>play()</code></dfn>
method on a <span>media element</span> is invoked, the user agent
must run the following steps.</p>
<ol>
<li><p>If the <span>media element</span>'s <code
title="dom-media-networkState">networkState</code> attribute has
the value <code
title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code>, invoke the
<span>media element</span>'s <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</p></li>
<li>
<p>If the <span title="ended playback">playback has ended</span>,
<span title="dom-media-seek">seek</span> to the <span>earliest
possible position</span> of the <span>media resource</span>.</p>
<p class="note">This <a href="#seekUpdate">will cause</a> the user
agent to <span>queue a task</span> to <span>fire a simple
event</span> named <code
title="event-media-timeupdate">timeupdate</code> at the <span>media
element</span>.</p> <!-- if we're already playing at this point,
it might also fire 'waiting' -->
</li>
<li>
<p>If the <span>media element</span>'s <code
title="dom-media-paused">paused</code> attribute is true, run
the following substeps:</p>
<ol>
<li><p>Change the value of <code
title="dom-media-paused">paused</code> to false.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple event</span>
named <code title="event-media-play">play</code> at the element.</p></li>
<li><p>If the <span>media element</span>'s <code
title="dom-media-readyState">readyState</code> attribute has the
value <code title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code>,
<code title="dom-media-HAVE_METADATA">HAVE_METADATA</code>, or
<code
title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code>,
<span>queue a task</span> to <span>fire a simple event</span>
named <code title="event-media-waiting">waiting</code> at the
element.</p></li>
<li><p>Otherwise, the <span>media element</span>'s <code
title="dom-media-readyState">readyState</code> attribute has the
value <code
title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code> or
<code title="dom-media-HAVE_ENOUGH_DATA">HAVE_ENOUGH_DATA</code>;
<span>queue a task</span> to <span>fire a simple event</span>
named <code title="event-media-playing">playing</code> at the
element.</p></li>
</ol>
</li>
<li><p>Set the <span>media element</span>'s <span>autoplaying
flag</span> to false.</p></li>
</ol>
<hr>
<p>When the <dfn title="dom-media-pause"><code>pause()</code></dfn>
method is invoked, the user agent must run the following steps:</p>
<ol>
<li><p>If the <span>media element</span>'s <code
title="dom-media-networkState">networkState</code> attribute has
the value <code
title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code>, invoke the
<span>media element</span>'s <span
title="concept-media-load-algorithm">resource selection
algorithm</span>.</p></li>
<li><p>Set the <span>media element</span>'s <span>autoplaying
flag</span> to false.</p></li>
<li><p>If the <span>media element</span>'s <code
title="dom-media-paused">paused</code> attribute is false, run the
following steps:</p>
<ol>
<li><p>Change the value of <code
title="dom-media-paused">paused</code> to true.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code
title="event-media-timeupdate">timeupdate</code> at the
element.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-pause">pause</code>
at the element.</p></li>
</ol>
</li>
</ol>
<hr>
<p id="media-playback">When a <span>media element</span> is
<span>potentially playing</span> and its <code>Document</code> is a
<span>fully active</span> <code>Document</code>, its <span>current
playback position</span> must increase monotonically at <code
title="dom-media-playbackRate">playbackRate</code> units of media
time per unit time of wall clock time.</p>
<p class="note">This specification doesn't define how the user agent
achieves the appropriate playback rate — depending on the
protocol and media available, it is plausible that the user agent
could negotiate with the server to have the server provide the media
data at the appropriate rate, so that (except for the period between
when the rate is changed and when the server updates the stream's
playback rate) the client doesn't actually have to drop or
interpolate any frames.</p>
<p>When the <code title="dom-media-playbackRate">playbackRate</code>
is negative (playback is backwards), any corresponding audio must be
muted. When the <code
title="dom-media-playbackRate">playbackRate</code> is so low or so
high that the user agent cannot play audio usefully, the
corresponding audio must also be muted. If the <code
title="dom-media-playbackRate">playbackRate</code> is not 1.0, the
user agent may apply pitch adjustments to the audio as necessary to
render it faithfully.</p>
<p>The <code title="dom-media-playbackRate">playbackRate</code> can
be 0.0, in which case the <span>current playback position</span>
doesn't move, despite playback not being paused (<code
title="dom-media-paused">paused</code> doesn't become true, and the
<code title="event-media-pause">pause</code> event doesn't fire).</p>
<p><span title="media element">Media elements</span> that are
<span>potentially playing</span> while not <span>in a
<code>Document</code></span> must not play any video, but should
play any audio component. Media elements must not stop playing just
because all references to them have been removed; only once a media
element to which no references exist has reached a point where no
further audio remains to be played for that element (e.g. because
the element is paused, or because the end of the clip has been
reached, or because its <code
title="dom-media-playbackRate">playbackRate</code> is 0.0) may the
element be garbage collected.</p>
<hr>
<p>When the <span>current playback position</span> of a <span>media
element</span> changes (e.g. due to playback or seeking), the user
agent must run the following steps. If the <span>current playback
position</span> changes while the steps are running, then the user
agent must wait for the steps to complete, and then must immediately
rerun the steps. (These steps are thus run as often as possible or
needed — if one iteration takes a long time, this can cause
certain ranges to be skipped over as the user agent rushes ahead to
"catch up".)</p>
<ol>
<!--v2CUERANGE
<li><p>Let <var title="">current ranges</var> be an ordered list of
<span title="cue range">cue ranges</span>, initialized to contain
all the <span title="cue range">cue ranges</span> of the
<span>media element</span> whose start times are less than or equal
to the <span>current playback position</span> and whose end times
are greater than the <span>current playback position</span>, in the
order they were added to the element.</p></li>
<li><p>Let <var title="">other ranges</var> be an ordered list of
<span title="cue range">cue ranges</span>, initialized to contain
all the <span title="cue range">cue ranges</span> of the
<span>media element</span> that are not present in <var
title="">current ranges</var>, in the order they were added to the
element.</p></li>
-->
<li><p>If the time was reached through the usual monotonic increase
of the current playback position during normal playback, and if the
user agent has not fired a <code
title="event-media-timeupdate">timeupdate</code> event at the element in
the past 15 to 250ms, then the user agent must <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-media-timeupdate">timeupdate</code> at the element. (In the
other cases, such as explicit seeks, relevant events get fired as
part of the overall process of changing the current playback
position.)</p>
<p class="note">The event thus is not to be fired faster than about
66Hz or slower than 4Hz. User agents are encouraged to vary the
frequency of the event based on the system load and the average
cost of processing the event each time, so that the UI updates are
not any more frequent than the user agent can comfortably handle
while decoding the video.</p></li>
<!--v2CUERANGE [beware - - nested comments]
<li><p>If none of the <span title="cue range">cue ranges</span> in
<var title="">current ranges</var> have their "active" boolean set
to "false" (inactive) and none of the <span title="cue range">cue
ranges</span> in <var title="">other ranges</var> have their
"active" boolean set to "true" (active), then abort these
steps.</p></li>
<li><p>If the time was reached through the usual monotonic increase
of the current playback position during normal playback, and there
are <span title="cue range">cue ranges</span> in <var
title="">other ranges</var> that have both their "active" boolean
and their "pause" boolean set to "true", then immediately act as if
the element's <code title="dom-media-pause">pause()</code> method
had been invoked. <!- - pause() can in theory call load(), but never
can it do so as part of this invokation, since we wouldn't be in
this algorithm if the media element was empty. So, no need to couch
all this in a task. - -> (In the other cases, such as explicit
seeks, playback is not paused by exiting a cue range, even if that
cue range has its "pause" boolean set to "true".)</p></li>
<li><p>For each non-null "exit" callback of the <span
title="cue range">cue ranges</span> in <var title="">other
ranges</var> that have their "active" boolean set to "true"
(active), in list order, <span>queue a task</span> that invokes the
callback, passing the cue range's identifier as the callback's only
argument.</p></li>
<li><p>For each non-null "enter" callback of the <span title="cue
range">cue ranges</span> in <var title="">current ranges</var> that
have their "active" boolean set to "false" (inactive), in list
order, <span>queue a task</span> that invokes the callback, passing
the cue range's identifier as the callback's only
argument.</p></li>
<li><p>Set the "active" boolean of all the <span title="cue
range">cue ranges</span> in the <var title="">current ranges</var>
list to "true" (active), and the "active" boolean of all the <span
title="cue range">cue ranges</span> in the <var title="">other
ranges</var> list to "false" (inactive).</p></li>
-->
</ol>
<p>When a <span>media element</span> is <span title="remove an
element from a document">removed from a
<code>Document</code></span>, if the <span>media element</span>'s
<code title="dom-media-networkState">networkState</code> attribute
has a value other than <code
title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code> then the user
agent must act as if the <code
title="dom-media-pause">pause()</code> method had been invoked.</p>
<p class="note">If the <span>media element</span>'s
<code>Document</code> stops being a <span>fully active</span>
document, then the playback will <a href="#media-playback">stop</a>
until the document is active again.</p>
</div>
<h5>Seeking</h5>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-seeking">seeking</code></dt>
<dd>
<p>Returns true if the user agent is currently seeking.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-seekable">seekable</code></dt>
<dd>
<p>Returns a <code>TimeRanges</code> object that represents the
ranges of the <span>media resource</span> to which it is possible
for the user agent to seek.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-media-seeking"><code>seeking</code></dfn>
attribute must initially have the value false.</p>
<p>When the user agent is required to <dfn
title="dom-media-seek">seek</dfn> to a particular <var title="">new
playback position</var> in the <span>media resource</span>, it means
that the user agent must run the following steps:</p>
<ol>
<li><p>If the <span>media element</span>'s <code
title="dom-media-readyState">readyState</code> is <code
title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code>, then the user
agent must raise an <code>INVALID_STATE_ERR</code> exception (if
the seek was in response to a DOM method call or setting of an IDL
attribute), and abort these steps.</p></li>
<li><p>If the <var title="">new playback position</var> is later
than the end of the <span>media resource</span>, then let it be the
end of the <span>media resource</span> instead.</p></li>
<li><p>If the <var title="">new playback position</var> is less
than the <span>earliest possible position</span>, let it be that
position instead.</p></li>
<li><p>If the (possibly now changed) <var title="">new playback
position</var> is not in one of the ranges given in the <code
title="dom-media-seekable">seekable</code> attribute, then the user
agent must raise an <code>INDEX_SIZE_ERR</code> exception (if the
seek was in response to a DOM method call or setting of an IDL
attribute), and abort these steps.</p></li>
<li><p>The <span>current playback position</span> must be set to
the given <var title="">new playback position</var>.</p></li>
<li><p>The <code title="dom-media-seeking">seeking</code> IDL
attribute must be set to true.</p></li>
<li id="seekUpdate"><p>The user agent must <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-media-timeupdate">timeupdate</code> at the element.</p></li>
<li><p>If the <span>media element</span> was <span>potentially
playing</span> immediately before it started seeking, but seeking
caused its <code title="dom-media-readyState">readyState</code>
attribute to change to a value lower than <code
title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code>, the
user agent must <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-media-waiting">waiting</code> at
the element.</p></li>
<li><p>If, when it reaches this step, the user agent has still not
established whether or not the <span>media data</span> for the <var
title="">new playback position</var> is available, and, if it is,
decoded enough data to play back that position, the user agent must
<span>queue a task</span> to <span>fire a simple event</span>
named <code title="event-media-seeking">seeking</code> at the
element.</p></li>
<li><p>If the seek was in response to a DOM method call or setting
of an IDL attribute, then continue the script. The remainder of
these steps must be run asynchronously.</p></li>
<li><p>The user agent must wait until it has established whether or
not the <span>media data</span> for the <var title="">new playback
position</var> is available, and, if it is, until it has decoded
enough data to play back that position.</p></li>
<li><p>The <code title="dom-media-seeking">seeking</code> IDL
attribute must be set to false.</p></li>
<li><p>The user agent must <span>queue a task</span> to <span>fire
a simple event</span> named <code
title="event-media-seeked">seeked</code> at the element.</p></li>
</ol>
<p>The <dfn title="dom-media-seekable"><code>seekable</code></dfn>
attribute must return a new static <span>normalized
<code>TimeRanges</code> object</span> that represents the ranges of
the <span>media resource</span>, if any, that the user agent is able
to seek to, at the time the attribute is evaluated.</p>
<p class="note">If the user agent can seek to anywhere in the
<span>media resource</span>, e.g. because it a simple movie file and
the user agent and the server support HTTP Range requests, then the
attribute would return an object with one range, whose start is the
time of the first frame (typically zero), and whose end is the same
as the time of the first frame plus the <code
title="dom-media-duration">duration</code> attribute's value (which
would equal the time of the last frame).</p>
<p class="note">The range might be continuously changing, e.g. if
the user agent is buffering a sliding window on an infinite
stream. This is the behavior seen with DVRs viewing live TV, for
instance.</p>
<p><span title="media resource">Media resources</span> might be
internally scripted or interactive. Thus, a <span>media
element</span> could play in a non-linear fashion. If this happens,
the user agent must act as if the algorithm for <span
title="dom-media-seek">seeking</span> was used whenever the
<span>current playback position</span> changes in a discontinuous
fashion (so that the relevant events fire).</p>
</div>
<h5>User interface</h5>
<p>The <dfn title="attr-media-controls"><code>controls</code></dfn>
attribute is a <span>boolean attribute</span>. If present, it
indicates that the author has not provided a scripted controller and
would like the user agent to provide its own set of controls.</p>
<div class="impl">
<p>If the attribute is present, or if <span
title="concept-n-noscript">scripting is disabled</span> for the
<span>media element</span>, then the user agent should <dfn>expose a
user interface to the user</dfn>. This user interface should include
features to begin playback, pause playback, seek to an arbitrary
position in the content (if the content supports arbitrary seeking),
change the volume, and show the media content in manners more
suitable to the user (e.g. full-screen video or in an independent
resizable window). Other controls may also be made available.</p>
<p>Even when the attribute is absent, however, user agents may
provide controls to affect playback of the media resource
(e.g. play, pause, seeking, and volume controls), but such features
should not interfere with the page's normal rendering. For example,
such features could be exposed in the <span>media element</span>'s
context menu.</p>
<p>Where possible (specifically, for starting, stopping, pausing,
and unpausing playback, for muting or changing the volume of the
audio, and for seeking), user interface features exposed by the user
agent must be implemented in terms of the DOM API described above,
so that, e.g., all the same events fire.</p>
<p>The <dfn title="dom-media-controls"><code>controls</code></dfn>
IDL attribute must <span>reflect</span> the content attribute of the
same name.</p>
<hr>
</div>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-media-volume">volume</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current playback volume, as a number in the range
0.0 to 1.0, where 0.0 is the quietest and 1.0 the loudest.</p>
<p>Can be set, to change the volume.</p>
<p>Throws an <code>INDEX_SIZE_ERR</code> if the new value is not
in the range 0.0 .. 1.0.</p>
</dd>
<dt><var title="">media</var> . <code title="dom-media-muted">muted</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns true if audio is muted, overriding the <code
title="dom-media-volume">volume</code> attribute, and false if the
<code title="dom-media-volume">volume</code> attribute is being
honored.</p>
<p>Can be set, to change whether the audio is muted or not.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-media-volume"><code>volume</code></dfn>
attribute must return the playback volume of any audio portions of
the <span>media element</span>, in the range 0.0 (silent) to 1.0
(loudest). Initially, the volume must be 1.0, but user agents may
remember the last set value across sessions, on a per-site basis or
otherwise, so the volume may start at other values. On setting, if
the new value is in the range 0.0 to 1.0 inclusive, the attribute
must be set to the new value and the playback volume must be
correspondingly adjusted as soon as possible after setting the
attribute, with 0.0 being silent, and 1.0 being the loudest setting,
values in between increasing in loudness. The range need not be
linear. The loudest setting may be lower than the system's loudest
possible setting; for example the user could have set a maximum
volume. If the new value is outside the range 0.0 to 1.0 inclusive,
then, on setting, an <code>INDEX_SIZE_ERR</code> exception must be
raised instead.</p>
<p>The <dfn title="dom-media-muted"><code>muted</code></dfn>
attribute must return true if the audio channels are muted and false
otherwise. Initially, the audio channels should not be muted
(false), but user agents may remember the last set value across
sessions, on a per-site basis or otherwise, so the muted state may
start as muted (true). On setting, the attribute must be set to the
new value; if the new value is true, audio playback for this
<span>media resource</span> must then be muted, and if false, audio
playback must then be enabled.</p>
<p>Whenever either the <code title="dom-media-muted">muted</code> or
<code title="dom-media-volume">volume</code> attributes are changed,
the user agent must <span>queue a task</span> to <span>fire a simple
event</span> named <code
title="event-media-volumechange">volumechange</code> at the <span>media
element</span>.</p>
</div>
<h5>Time ranges</h5>
<p>Objects implementing the <code>TimeRanges</code> interface
represent a list of ranges (periods) of time.</p>
<pre class="idl">interface <dfn>TimeRanges</dfn> {
readonly attribute unsigned long <span title="dom-TimeRanges-length">length</span>;
float <span title="dom-TimeRanges-start">start</span>(in unsigned long index);
float <span title="dom-TimeRanges-end">end</span>(in unsigned long index);
};</pre>
<dl class="domintro">
<dt><var title="">media</var> . <code title="dom-TimeRanges-length">length</code></dt>
<dd>
<p>Returns the number of ranges in the object.</p>
</dd>
<dt><var title="">time</var> = <var title="">media</var> . <code title="dom-TimeRanges-start">start</code>(<var title="">index</var>)</dt>
<dd>
<p>Returns the time for the start of the range with the given index.</p>
<p>Throws an <code>INDEX_SIZE_ERR</code> if the index is out of range.</p>
</dd>
<dt><var title="">time</var> = <var title="">media</var> . <code title="dom-TimeRanges-end">end</code>(<var title="">index</var>)</dt>
<dd>
<p>Returns the time for the end of the range with the given index.</p>
<p>Throws an <code>INDEX_SIZE_ERR</code> if the index is out of range.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-TimeRanges-length"><code>length</code></dfn>
IDL attribute must return the number of ranges represented by the object.</p>
<p>The <dfn title="dom-TimeRanges-start"><code>start(<var
title="">index</var>)</code></dfn> method must return the position
of the start of the <var title="">index</var>th range represented by
the object, in seconds measured from the start of the timeline that
the object covers.</p>
<p>The <dfn title="dom-TimeRanges-end"><code>end(<var
title="">index</var>)</code></dfn> method must return the position
of the end of the <var title="">index</var>th range represented by
the object, in seconds measured from the start of the timeline that
the object covers.</p>
<p>These methods must raise <code>INDEX_SIZE_ERR</code> exceptions
if called with an <var title="">index</var> argument greater than or
equal to the number of ranges represented by the object.</p>
<p>When a <code>TimeRanges</code> object is said to be a
<dfn>normalized <code>TimeRanges</code> object</dfn>, the ranges it
represents must obey the following criteria:</p>
<ul>
<li>The start of a range must be greater than the end of all
earlier ranges.</li>
<li>The start of a range must be less than the end of that same
range.</li>
</ul>
<p>In other words, the ranges in such an object are ordered, don't
overlap, aren't empty, and don't touch (adjacent ranges are folded
into one bigger range).</p>
<p>The timelines used by the objects returned by the <code
title="dom-media-buffered">buffered</code>, <code
title="dom-media-seekable">seekable</code> and <code
title="dom-media-played">played</code> IDL attributes of <span
title="media element">media elements</span> must be the same as that
element's <span>media resource</span>'s timeline.</p>
</div>
<h5 id="mediaevents">Event summary</h5>
<p><i>This section is non-normative.</i></p>
<p>The following events fire on <span title="media element">media
elements</span> as part of the processing model described above:</p>
<table>
<thead>
<tr>
<th>Event name
<th>Interface
<th>Dispatched when...
<th>Preconditions
<tbody>
<tr>
<td><dfn title="event-media-loadstart"><code>loadstart</code></dfn>
<td><code>Event</code>
<td>The user agent begins looking for <span>media data</span>, as part of the <span title="concept-media-load-algorithm">resource selection algorithm</span>.
<td><code title="dom-media-networkState">networkState</code> equals <code title="dom-media-NETWORK_LOADING">NETWORK_LOADING</code>
<tr>
<td><dfn title="event-media-progress"><code>progress</code></dfn>
<td><code>Event</code>
<td>The user agent is fetching <span>media data</span>.
<td><code title="dom-media-networkState">networkState</code> equals <code title="dom-media-NETWORK_LOADING">NETWORK_LOADING</code>
<tr>
<td><dfn title="event-media-suspend"><code>suspend</code></dfn>
<td><code>Event</code>
<td>The user agent is intentionally not currently fetching <span>media data</span>, but does not have the entire <span>media resource</span> downloaded.
<td><code title="dom-media-networkState">networkState</code> equals <code title="dom-media-NETWORK_IDLE">NETWORK_IDLE</code>
<tr>
<td><dfn title="event-media-abort"><code>abort</code></dfn>
<td><code>Event</code>
<td>The user agent stops fetching the <span>media data</span> before it is completely downloaded, but not due to an error.
<td><code title="dom-media-error">error</code> is an object with the code <code title="dom-MediaError-MEDIA_ERR_ABORTED">MEDIA_ERR_ABORTED</code>.
<code title="dom-media-networkState">networkState</code> equals either <code title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code> or <code title="dom-media-NETWORK_IDLE">NETWORK_IDLE</code>, depending on when the download was aborted.
<tr>
<td><dfn title="event-media-error"><code>error</code></dfn>
<td><code>Event</code>
<td>An error occurs while fetching the <span>media data</span>.
<td><code title="dom-media-error">error</code> is an object with the code <code title="dom-MediaError-MEDIA_ERR_NETWORK">MEDIA_ERR_NETWORK</code> or higher.
<code title="dom-media-networkState">networkState</code> equals either <code title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code> or <code title="dom-media-NETWORK_IDLE">NETWORK_IDLE</code>, depending on when the download was aborted.
<tr>
<td><dfn title="event-media-emptied"><code>emptied</code></dfn>
<td><code>Event</code>
<td>A <span>media element</span> whose <code title="dom-media-networkState">networkState</code> was previously not in the <code title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code> state has just switched to that state (either because of a fatal error during load that's about to be reported, or because the <code title="dom-media-load">load()</code> method was invoked while the <span title="concept-media-load-algorithm">resource selection algorithm</span> was already running, in which case it is fired synchronously during the <code title="dom-media-load">load()</code> method call).
<td><code title="dom-media-networkState">networkState</code> is <code title="dom-media-NETWORK_EMPTY">NETWORK_EMPTY</code>; all the IDL attributes are in their initial states.
<tr>
<td><dfn title="event-media-stalled"><code>stalled</code></dfn>
<td><code>Event</code>
<td>The user agent is trying to fetch <span>media data</span>, but data is unexpectedly not forthcoming.
<td><code title="dom-media-networkState">networkState</code> is <code title="dom-media-NETWORK_LOADING">NETWORK_LOADING</code>.
<tbody>
<tr>
<td><dfn title="event-media-play"><code>play</code></dfn>
<td><code>Event</code>
<td>Playback has begun. Fired after the <code title="dom-media-play">play()</code> method has returned.
<td><code title="dom-media-paused">paused</code> is newly false.
<tr>
<td><dfn title="event-media-pause"><code>pause</code></dfn>
<td><code>Event</code>
<td>Playback has been paused. Fired after the <code title="dom-media-pause">pause</code> method has returned.
<td><code title="dom-media-paused">paused</code> is newly true.
<tbody>
<tr>
<td><dfn title="event-media-loadedmetadata"><code>loadedmetadata</code></dfn>
<td><code>Event</code>
<td>The user agent has just determined the duration and dimensions of the <span>media resource</span>.
<td><code title="dom-media-readyState">readyState</code> is newly equal to <code title="dom-media-HAVE_METADATA">HAVE_METADATA</code> or greater for the first time.
<tr>
<td><dfn title="event-media-loadeddata"><code>loadeddata</code></dfn>
<td><code>Event</code>
<td>The user agent can render the <span>media data</span> at the <span>current playback position</span> for the first time.
<td><code title="dom-media-readyState">readyState</code> newly increased to <code title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code> or greater for the first time.
<tr>
<td><dfn title="event-media-waiting"><code>waiting</code></dfn>
<td><code>Event</code>
<td>Playback has stopped because the next frame is not available, but the user agent expects that frame to become available in due course.
<td><code title="dom-media-readyState">readyState</code> is newly equal to or less than <code title="dom-media-HAVE_CURRENT_DATA">HAVE_CURRENT_DATA</code>, and <code title="dom-media-paused">paused</code> is false. Either <code title="dom-media-seeking">seeking</code> is true, or the <span>current playback position</span> is not contained in any of the ranges in <code title="dom-media-buffered">buffered</code>. It is possible for playback to stop for two other reasons without <code title="dom-media-paused">paused</code> being false, but those two reasons do not fire this event: maybe <span title="ended playback">playback ended</span>, or playback <span>stopped due to errors</span>.
<tr>
<td><dfn title="event-media-playing"><code>playing</code></dfn>
<td><code>Event</code>
<td>Playback has started.
<td><code title="dom-media-readyState">readyState</code> is newly equal to or greater than <code title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code>, <code title="dom-media-paused">paused</code> is false, <code title="dom-media-seeking">seeking</code> is false, or the <span>current playback position</span> is contained in one of the ranges in <code title="dom-media-buffered">buffered</code>.
<tr>
<td><dfn title="event-media-canplay"><code>canplay</code></dfn>
<td><code>Event</code>
<td>The user agent can resume playback of the <span>media data</span>, but estimates that if playback were to be started now, the <span>media resource</span> could not be rendered at the current playback rate up to its end without having to stop for further buffering of content.
<td><code title="dom-media-readyState">readyState</code> newly increased to <code title="dom-media-HAVE_FUTURE_DATA">HAVE_FUTURE_DATA</code> or greater.
<tr>
<td><dfn title="event-media-canplaythrough"><code>canplaythrough</code></dfn>
<td><code>Event</code>
<td>The user agent estimates that if playback were to be started now, the <span>media resource</span> could be rendered at the current playback rate all the way to its end without having to stop for further buffering.
<td><code title="dom-media-readyState">readyState</code> is newly equal to <code title="dom-media-HAVE_ENOUGH_DATA">HAVE_ENOUGH_DATA</code>.
<tbody>
<tr>
<td><dfn title="event-media-seeking"><code>seeking</code></dfn>
<td><code>Event</code>
<td>The <code title="dom-media-seeking">seeking</code> IDL attribute changed to true and the seek operation is taking long enough that the user agent has time to fire the event.
<td>
<tr>
<td><dfn title="event-media-seeked"><code>seeked</code></dfn>
<td><code>Event</code>
<td>The <code title="dom-media-seeking">seeking</code> IDL attribute changed to false.
<td>
<tr>
<td><dfn title="event-media-timeupdate"><code>timeupdate</code></dfn>
<td><code>Event</code>
<td>The <span>current playback position</span> changed as part of normal playback or in an especially interesting way, for example discontinuously.
<td>
<tr>
<td><dfn title="event-media-ended"><code>ended</code></dfn>
<td><code>Event</code>
<td>Playback has stopped because the end of the <span>media resource</span> was reached.
<td><code title="dom-media-currentTime">currentTime</code> equals the end of the <span>media resource</span>; <code title="dom-media-ended">ended</code> is true.
<tbody>
<tr>
<td><dfn title="event-media-ratechange"><code>ratechange</code></dfn>
<td><code>Event</code>
<td>Either the <code title="dom-media-defaultPlaybackRate">defaultPlaybackRate</code> or the <code title="dom-media-playbackRate">playbackRate</code> attribute has just been updated.
<td>
<tr>
<td><dfn title="event-media-durationchange"><code>durationchange</code></dfn>
<td><code>Event</code>
<td>The <code title="dom-media-duration">duration</code> attribute has just been updated.
<td>
<tr>
<td><dfn title="event-media-volumechange"><code>volumechange</code></dfn>
<td><code>Event</code>
<td>Either the <code title="dom-media-volume">volume</code> attribute or the <code title="dom-media-muted">muted</code> attribute has changed. Fired after the relevant attribute's setter has returned.
<td>
</table>
<div class="impl">
<h5>Security and privacy considerations</h5>
<p>The main security and privacy implications of the
<code>video</code> and <code>audio</code> elements come from the
ability to embed media cross-origin. There are two directions that
threats can flow: from hostile content to a victim page, and from a
hostile page to victim content.</p>
<hr>
<p>If a victim page embeds hostile content, the threat is that the
content might contain scripted code that attempts to interact with
the <code>Document</code> that embeds the content. To avoid this,
user agents must ensure that there is no access from the content to
the embedding page. In the case of media content that uses DOM
concepts, the embedded content must be treated as if it was in its
own unrelated <span>top-level browsing context</span>.</p>
<p class="example">For instance, if an SVG animation was embedded in
a <code>video</code> element, the user agent would not give it
access to the DOM of the outer page. From the perspective of scripts
in the SVG resource, the SVG file would appear to be in a lone
top-level browsing context with no parent.</p>
<hr>
<p>If a hostile page embeds victim content, the threat is that the
embedding page could obtain information from the content that it
would not otherwise have access to. The API does expose some
information: the existence of the media, its type, its duration, its
size, and the performance characteristics of its host. Such
information is already potentially problematic, but in practice the
same information can more or less be obtained using the
<code>img</code> element, and so it has been deemed acceptable.</p>
<p>However, significantly more sensitive information could be
obtained if the user agent further exposes metadata within the
content such as subtitles or chapter titles. This version of the API
does not expose such information. Future extensions to this API will
likely reuse a mechanism such as CORS to check that the embedded
content's site has opted in to exposing such information. <a
href="#refsCORS">[CORS]</a></p> <!-- v2 -->
<p class="example">An attacker could trick a user running within a
corporate network into visiting a site that attempts to load a video
from a previously leaked location on the corporation's intranet. If
such a video included confidential plans for a new product, then
being able to read the subtitles would present a confidentiality
breach.</p>
</div>
<h4>The <dfn id="canvas"><code>canvas</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Embedded content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>embedded content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Transparent</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-canvas-width">width</code></dd>
<dd><code title="attr-canvas-height">height</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLCanvasElement</dfn> : <span>HTMLElement</span> {
attribute unsigned long <span title="dom-canvas-width">width</span>;
attribute unsigned long <span title="dom-canvas-height">height</span>;
DOMString <span title="dom-canvas-toDataURL">toDataURL</span>(in optional DOMString type, in any... args);
object <span title="dom-canvas-getContext">getContext</span>(in DOMString contextId);
};</pre>
</dd>
</dl>
<p>The <code>canvas</code> element provides scripts with a
resolution-dependent bitmap canvas, which can be used for rendering
graphs, game graphics, or other visual images on the fly.</p>
<p>Authors should not use the <code>canvas</code> element in a
document when a more suitable element is available. For example, it
is inappropriate to use a <code>canvas</code> element to render a
page heading: if the desired presentation of the heading is
graphically intense, it should be marked up using appropriate
elements (typically <code>h1</code>) and then styled using CSS and
supporting technologies such as XBL.</p>
<p>When authors use the <code>canvas</code> element, they must also
provide content that, when presented to the user, conveys
essentially the same function or purpose as the bitmap canvas. This
content may be placed as content of the <code>canvas</code>
element. The contents of the <code>canvas</code> element, if any,
are the element's <span>fallback content</span>.</p>
<p>In interactive visual media, if <span
title="concept-n-script">scripting is enabled</span> for the
<code>canvas</code> element, and if support for <code>canvas</code>
elements has been enabled, the <code>canvas</code> element
<span>represents</span> <span>embedded content</span> consisting of
a dynamically created image.</p>
<p>In non-interactive, static, visual media, if the
<code>canvas</code> element has been previously painted on (e.g. if
the page was viewed in an interactive visual medium and is now being
printed, or if some script that ran during the page layout process
painted on the element), then the <code>canvas</code> element
<span>represents</span> <span>embedded content</span> with the
current image and size. Otherwise, the element represents its
<span>fallback content</span> instead.</p>
<p>In non-visual media, and in visual media if <span
title="concept-n-noscript">scripting is disabled</span> for the
<code>canvas</code> element or if support for <code>canvas</code>
elements has been disabled, the <code>canvas</code> element
<span>represents</span> its <span>fallback content</span>
instead.</p>
<!-- CANVAS-FOCUS-FALLBACK -->
<p>When a <code>canvas</code> element <span>represents</span>
<span>embedded content</span>, the user can still focus descendants
of the <code>canvas</code> element (in the <span>fallback
content</span>). This allows authors to make an interactive canvas
keyboard-focusable: authors should have a one-to-one mapping of
interactive regions to focusable elements in the <span>fallback
content</span>.</p>
<p>The <code>canvas</code> element has two attributes to control the
size of the coordinate space: <dfn
title="attr-canvas-width"><code>width</code></dfn> and <dfn
title="attr-canvas-height"><code>height</code></dfn>. These
attributes, when specified, must have values that are <span
title="valid non-negative integer">valid non-negative
integers</span>. <span class="impl">The <span>rules for parsing
non-negative integers</span> must be used to obtain their numeric
values. If an attribute is missing, or if parsing its value returns
an error, then the default value must be used instead.</span> The
<code title="attr-canvas-width">width</code> attribute defaults to
300, and the <code title="attr-canvas-height">height</code>
attribute defaults to 150.</p>
<p>The intrinsic dimensions of the <code>canvas</code> element equal
the size of the coordinate space, with the numbers interpreted in
CSS pixels. However, the element can be sized arbitrarily by a
style sheet. During rendering, the image is scaled to fit this layout
size.</p>
<div class="impl">
<p>The size of the coordinate space does not necessarily represent
the size of the actual bitmap that the user agent will use
internally or during rendering. On high-definition displays, for
instance, the user agent may internally use a bitmap with two device
pixels per unit in the coordinate space, so that the rendering
remains at high quality throughout.</p>
<p>When the <code>canvas</code> element is created, and subsequently
whenever the <code title="attr-canvas-width">width</code> and <code
title="attr-canvas-height">height</code> attributes are set (whether
to a new value or to the previous value), the bitmap and any
associated contexts must be cleared back to their initial state and
reinitialized with the newly specified coordinate space
dimensions.</p>
<p>When the canvas is initialized, its bitmap must be cleared to
transparent black.</p>
<p>The <dfn title="dom-canvas-width"><code>width</code></dfn> and
<dfn title="dom-canvas-height"><code>height</code></dfn> IDL
attributes must <span>reflect</span> the respective content
attributes of the same name.</p>
</div>
<div class="example">
<p>Only one square appears to be drawn in the following example:</p>
<pre> // canvas is a reference to a <canvas> element
var context = canvas.getContext('2d');
context.fillRect(0,0,50,50);
canvas.setAttribute('width', '300'); // clears the canvas
context.fillRect(0,100,50,50);
canvas.width = canvas.width; // clears the canvas
context.fillRect(100,0,50,50); // only this square remains</pre>
</div>
<p>To draw on the canvas, authors must first obtain a reference to a
<dfn>context</dfn> using the <dfn
title="dom-canvas-getContext"><code>getContext(<var
title="">contextId</var>)</code></dfn> method of the
<code>canvas</code> element.</p>
<dl class="domintro">
<dt><var title="">context</var> = <var title="">canvas</var> . <code title="dom-canvas-getContext">getContext</code>(<var title="">contextId</var>)</dt>
<dd>
<p>Returns an object that exposes an API for drawing on the canvas.</p>
<p>Returns null if the given context ID is not supported.</p>
</dd>
</dl>
<p>This specification only defines one context, with the name "<code
title="canvas-context-2d">2d</code>". <span class="impl">If <code
title="dom-canvas-getContext">getContext()</code> is called with
that exact string for its <var title="">contextId</var> argument,
then the UA must return a reference to an object implementing
<code>CanvasRenderingContext2D</code>. Other specifications may
define their own contexts, which would return different
objects.</span></p>
<div class="impl">
<p>Vendors may also define experimental contexts using the syntax
<code><var title="">vendorname</var>-<var
title="">context</var></code>, for example, <code>moz-3d</code>.</p>
<p>When the UA is passed an empty string or a string specifying a
context that it does not support, then it must return null. String
comparisons must be <span>case-sensitive</span>.</p>
</div>
<p class="note">A future version of this specification will probably
define a <code>3d</code> context (probably based on the OpenGL ES
API).</p>
<hr>
<dl class="domintro">
<dt><var title="">url</var> = <var title="">canvas</var> . <code title="dom-canvas-toDataURL">toDataURL</code>( [ <var title="">type</var>, ... ])</dt>
<dd>
<p>Returns a <code title="">data:</code> URL for the image in the
canvas.</p>
<p>The first argument, if provided, controls the type of the image
to be returned (e.g. PNG or JPEG). The default is <code
title="">image/png</code>; that type is also used if the given
type isn't supported. The other arguments are specific to the
type, and control the way that the image is generated, as given in
the table below.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-canvas-toDataURL"><code>toDataURL()</code></dfn> method
must, when called with no arguments, return a <code
title="">data:</code> URL containing a representation of the image
as a PNG file. <a href="#refsPNG">[PNG]</a></p>
<p>If the canvas has no pixels (i.e. either its horizontal dimension
or its vertical dimension is zero) then the method must return the
string "<code title="">data:,</code>". (This is the shortest <code
title="">data:</code> URL; it represents the empty string in a <code
title="">text/plain</code> resource.)</p>
<p>When the <code title="dom-canvas-toDataURL">toDataURL(<var
title="">type</var>)</code> method is called with one <em>or
more</em> arguments, it must return a <code title="">data:</code>
URL containing a representation of the image in the format given by
<var title="">type</var>. The possible values are <span title="MIME
type">MIME types</span> with no parameters, for example
<code>image/png</code>, <code>image/jpeg</code>, or even maybe
<code>image/svg+xml</code> if the implementation actually keeps
enough information to reliably render an SVG image from the
canvas.</p>
<p>For image types that do not support an alpha channel, the image
must be composited onto a solid black background using the
source-over operator, and the resulting image must be the one used
to create the <code title="">data:</code> URL.</p>
<p>Only support for <code>image/png</code> is required. User agents
may support other types. If the user agent does not support the
requested type, it must return the image using the PNG format.</p>
<p>User agents must <span title="converted to ASCII lowercase">convert the
provided type to ASCII lowercase</span> before establishing if they
support that type and before creating the <code
title="">data:</code> URL.</p>
</div>
<p class="note">When trying to use types other than
<code>image/png</code>, authors can check if the image was really
returned in the requested format by checking to see if the returned
string starts with one the exact strings "<code
title="">data:image/png,</code>" or "<code
title="">data:image/png;</code>". If it does, the image is PNG, and
thus the requested type was not supported. (The one exception to
this is if the canvas has either no height or no width, in which
case the result might simply be "<code title="">data:,</code>".)</p>
<div class="impl">
<p>If the method is invoked with the first argument giving a type
corresponding to one of the types given in the first column of the
following table, and the user agent supports that type, then the
subsequent arguments, if any, must be treated as described in the
second cell of that row.</p>
</div>
<table>
<thead>
<tr> <th> Type <th> Other arguments
<tbody>
<tr>
<td> image/jpeg
<td> The second argument<span class="impl">, if it</span> is a
number between 0.0 and 1.0<span class="impl">, must be</span>
treated as the desired quality level. <span class="impl">If it is
not a number or is outside that range, the user agent must use
its default value, as if the argument had been omitted.</span>
</table>
<div class="impl">
<p>Other arguments must be ignored and must not cause the user agent
to raise an exception. A future version of this specification will
probably define other parameters to be passed to <code
title="dom-canvas-toDataURL">toDataURL()</code> to allow authors to
more carefully control compression settings, image metadata,
etc.</p>
</div>
<h5>The 2D context</h5>
<!-- v2: we're on v3. suggestions for next version are marked v4. -->
<p>When the <code title="dom-canvas-getContext">getContext()</code>
method of a <code>canvas</code> element is invoked with <dfn
title="canvas-context-2d"><code>2d</code></dfn> as the argument, a
<code>CanvasRenderingContext2D</code> object is returned.</p>
<div class="impl">
<p>There is only one <code>CanvasRenderingContext2D</code> object
per canvas, so calling the <code
title="dom-canvas-getContext">getContext()</code> method with the
<code title="canvas-context-2d">2d</code> argument a second time
must return the same object.</p>
</div>
<p>The 2D context represents a flat Cartesian surface whose origin
(0,0) is at the top left corner, with the coordinate space having
<var title="">x</var> values increasing when going right, and <var
title="">y</var> values increasing when going down.</p>
<pre class="idl">interface <dfn>CanvasRenderingContext2D</dfn> {
// back-reference to the canvas
readonly attribute <span>HTMLCanvasElement</span> <span title="dom-context-2d-canvas">canvas</span>;
// state
void <span title="dom-context-2d-save">save</span>(); // push state on state stack
void <span title="dom-context-2d-restore">restore</span>(); // pop state stack and restore state
<!--
// v4 we've also received requests for:
attribute boolean <span title="dom-context-2d-forceHighQuality">forceHighQuality</span> // (default false)
// when enabled, it would prevent the UA from falling back on lower-quality but faster rendering routines
// useful e.g. for when an image manipulation app uses <canvas> both for UI previews and the actual work
-->
// transformations (default transform is the identity matrix)
void <span title="dom-context-2d-scale">scale</span>(in float x, in float y);
void <span title="dom-context-2d-rotate">rotate</span>(in float angle);
void <span title="dom-context-2d-translate">translate</span>(in float x, in float y);
void <span title="dom-context-2d-transform">transform</span>(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
void <span title="dom-context-2d-setTransform">setTransform</span>(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
<!--
// v4 we've also received requests for:
void skew(...);
void reflect(...); // or mirror(...)
-->
// compositing
attribute float <span title="dom-context-2d-globalAlpha">globalAlpha</span>; // (default 1.0)
attribute DOMString <span title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</span>; // (default source-over)
<!--
// v4 we've also received requests for:
- turning off antialiasing to avoid seams when patterns are painted next to each other
- might be better to overdraw?
- might be better to just draw at a higher res then downsample, like for 3d?
- nested layers
- the ability to composite an entire set of drawing operations with one shadow all at once
http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2008-August/015567.html
-->
// colors and styles
attribute any <span title="dom-context-2d-strokeStyle">strokeStyle</span>; // (default black)
attribute any <span title="dom-context-2d-fillStyle">fillStyle</span>; // (default black)
<span>CanvasGradient</span> <span title="dom-context-2d-createLinearGradient">createLinearGradient</span>(in float x0, in float y0, in float x1, in float y1);
<span>CanvasGradient</span> <span title="dom-context-2d-createRadialGradient">createRadialGradient</span>(in float x0, in float y0, in float r0, in float x1, in float y1, in float r1);
<span>CanvasPattern</span> <span title="dom-context-2d-createPattern">createPattern</span>(in <span>HTMLImageElement</span> image, in DOMString repetition);
<span>CanvasPattern</span> <span title="dom-context-2d-createPattern">createPattern</span>(in <span>HTMLCanvasElement</span> image, in DOMString repetition);
<span>CanvasPattern</span> <span title="dom-context-2d-createPattern">createPattern</span>(in <span>HTMLVideoElement</span> image, in DOMString repetition);
// line caps/joins
attribute float <span title="dom-context-2d-lineWidth">lineWidth</span>; // (default 1)
attribute DOMString <span title="dom-context-2d-lineCap">lineCap</span>; // "butt", "round", "square" (default "butt")
attribute DOMString <span title="dom-context-2d-lineJoin">lineJoin</span>; // "round", "bevel", "miter" (default "miter")
attribute float <span title="dom-context-2d-miterLimit">miterLimit</span>; // (default 10)
// shadows
attribute float <span title="dom-context-2d-shadowOffsetX">shadowOffsetX</span>; // (default 0)
attribute float <span title="dom-context-2d-shadowOffsetY">shadowOffsetY</span>; // (default 0)
attribute float <span title="dom-context-2d-shadowBlur">shadowBlur</span>; // (default 0)
attribute DOMString <span title="dom-context-2d-shadowColor">shadowColor</span>; // (default transparent black)
// rects
void <span title="dom-context-2d-clearRect">clearRect</span>(in float x, in float y, in float w, in float h);
void <span title="dom-context-2d-fillRect">fillRect</span>(in float x, in float y, in float w, in float h);
void <span title="dom-context-2d-strokeRect">strokeRect</span>(in float x, in float y, in float w, in float h);
// path API
void <span title="dom-context-2d-beginPath">beginPath</span>();
void <span title="dom-context-2d-closePath">closePath</span>();
void <span title="dom-context-2d-moveTo">moveTo</span>(in float x, in float y);
void <span title="dom-context-2d-lineTo">lineTo</span>(in float x, in float y);
void <span title="dom-context-2d-quadraticCurveTo">quadraticCurveTo</span>(in float cpx, in float cpy, in float x, in float y);
void <span title="dom-context-2d-bezierCurveTo">bezierCurveTo</span>(in float cp1x, in float cp1y, in float cp2x, in float cp2y, in float x, in float y);
void <span title="dom-context-2d-arcTo">arcTo</span>(in float x1, in float y1, in float x2, in float y2, in float radius);
void <span title="dom-context-2d-rect">rect</span>(in float x, in float y, in float w, in float h);
void <span title="dom-context-2d-arc">arc</span>(in float x, in float y, in float radius, in float startAngle, in float endAngle, in boolean anticlockwise);
void <span title="dom-context-2d-fill">fill</span>();
void <span title="dom-context-2d-stroke">stroke</span>();
void <span title="dom-context-2d-clip">clip</span>();
boolean <span title="dom-context-2d-isPointInPath">isPointInPath</span>(in float x, in float y);
// text
attribute DOMString <span title="dom-context-2d-font">font</span>; // (default 10px sans-serif)
attribute DOMString <span title="dom-context-2d-textAlign">textAlign</span>; // "start", "end", "left", "right", "center" (default: "start")
attribute DOMString <span title="dom-context-2d-textBaseline">textBaseline</span>; // "top", "hanging", "middle", "alphabetic", "ideographic", "bottom" (default: "alphabetic")
void <span title="dom-context-2d-fillText">fillText</span>(in DOMString text, in float x, in float y, in optional float maxWidth);
void <span title="dom-context-2d-strokeText">strokeText</span>(in DOMString text, in float x, in float y, in optional float maxWidth);<!-- v4DVT
void <span title="dom-context-2d-fillVerticalText">fillVerticalText</span>(in DOMString text, in float x, in float y, in optional float maxHeight);
void <span title="dom-context-2d-strokeVerticalText">strokeVerticalText</span>(in DOMString text, in float x, in float y, in optional float maxHeight); -->
<span>TextMetrics</span> <span title="dom-context-2d-measureText">measureText</span>(in DOMString text);
// drawing images
void <span title="dom-context-2d-drawImage">drawImage</span>(in <span>HTMLImageElement</span> image, in float dx, in float dy, in optional float dw, in float dh);
void <span title="dom-context-2d-drawImage">drawImage</span>(in <span>HTMLImageElement</span> image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);
void <span title="dom-context-2d-drawImage">drawImage</span>(in <span>HTMLCanvasElement</span> image, in float dx, in float dy, in optional float dw, in float dh);
void <span title="dom-context-2d-drawImage">drawImage</span>(in <span>HTMLCanvasElement</span> image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);
void <span title="dom-context-2d-drawImage">drawImage</span>(in <span>HTMLVideoElement</span> image, in float dx, in float dy, in optional float dw, in float dh);
void <span title="dom-context-2d-drawImage">drawImage</span>(in <span>HTMLVideoElement</span> image, in float sx, in float sy, in float sw, in float sh, in float dx, in float dy, in float dw, in float dh);
// pixel manipulation
<span>ImageData</span> <span title="dom-context-2d-createImageData">createImageData</span>(in float sw, in float sh);
<span>ImageData</span> <span title="dom-context-2d-createImageData">createImageData</span>(in <span>ImageData</span> imagedata);
<span>ImageData</span> <span title="dom-context-2d-getImageData">getImageData</span>(in float sx, in float sy, in float sw, in float sh);
void <span title="dom-context-2d-putImageData">putImageData</span>(in <span>ImageData</span> imagedata, in float dx, in float dy, in optional float dirtyX, in float dirtyY, in float dirtyWidth, in float dirtyHeight);
};
interface <dfn>CanvasGradient</dfn> {
// opaque object
void <span title="dom-canvasgradient-addColorStop">addColorStop</span>(in float offset, in DOMString color);
};
interface <dfn>CanvasPattern</dfn> {
// opaque object
};
interface <dfn>TextMetrics</dfn> {
readonly attribute float <span title="dom-textmetrics-width">width</span>;
};
interface <dfn>ImageData</dfn> {
readonly attribute unsigned long <span title="dom-imagedata-width">width</span>;
readonly attribute unsigned long <span title="dom-imagedata-height">height</span>;
readonly attribute <span>CanvasPixelArray</span> <span title="dom-imagedata-data">data</span>;
};
interface <dfn>CanvasPixelArray</dfn> {
readonly attribute unsigned long <span title="dom-canvaspixelarray-length">length</span>;
<span title="dom-CanvasPixelArray-get">getter</span> octet (in unsigned long index);
<span title="dom-CanvasPixelArray-set">setter</span> void (in unsigned long index, in octet value);
};</pre>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-canvas">canvas</code></dt>
<dd>
<p>Returns the <code>canvas</code> element.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-context-2d-canvas"><code>canvas</code></dfn>
attribute must return the <code>canvas</code> element that the
context paints on.</p>
<p>Except where otherwise specified, for the 2D context interface,
any method call with a numeric argument whose value is infinite or a
NaN value must be ignored.</p>
<!--
Philip Taylor wrote:
> My experience with some 3d canvas code is that infinities come up in
> naturally harmless places, e.g. having a function that scales by x then
> translates by 1/x and wanting it to work when x=0 (which ought to draw
> nothing, since anything it draws is zero pixels wide), and it's a bit
> annoying to track down and fix those issues, so I'd probably like it if
> they were harmless in canvas methods. Opera appears to silently not draw
> anything if the transformation matrix is not finite, but Firefox throws
> exceptions when passing in non-finite arguments.
-->
<p>Whenever the CSS value <code title="">currentColor</code> is used
as a color in this API, the "computed value of the 'color' property"
for the purposes of determining the computed value of the <code
title="">currentColor</code> keyword is the computed value of the
'color' property on the element in question at the time that the
color is specified (e.g. when the appropriate attribute is set, or
when the method is called; not when the color is rendered or
otherwise used). If the computed value of the 'color' property is
undefined for a particular case (e.g. because the element is not
<span>in a <code>Document</code></span>), then the "computed value
of the 'color' property" for the purposes of determining the
computed value of the <code title="">currentColor</code> keyword is
fully opaque black. <a href="#refsCSSCOLOR">[CSSCOLOR]</a></p>
</div>
<h6>The canvas state</h6>
<p>Each context maintains a stack of drawing states. <dfn
title="drawing state">Drawing states</dfn> consist of:</p>
<ul class="brief">
<li>The current <span title="dom-context-2d-transformation">transformation matrix</span>.</li>
<li>The current <span>clipping region</span>.</li>
<li>The current values of the following attributes: <code
title="dom-context-2d-strokeStyle">strokeStyle</code>, <code
title="dom-context-2d-fillStyle">fillStyle</code>, <code
title="dom-context-2d-globalAlpha">globalAlpha</code>, <code
title="dom-context-2d-lineWidth">lineWidth</code>, <code
title="dom-context-2d-lineCap">lineCap</code>, <code
title="dom-context-2d-lineJoin">lineJoin</code>, <code
title="dom-context-2d-miterLimit">miterLimit</code>, <code
title="dom-context-2d-shadowOffsetX">shadowOffsetX</code>, <code
title="dom-context-2d-shadowOffsetY">shadowOffsetY</code>, <code
title="dom-context-2d-shadowBlur">shadowBlur</code>, <code
title="dom-context-2d-shadowColor">shadowColor</code>, <code
title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</code>, <code
title="dom-context-2d-font">font</code>, <code
title="dom-context-2d-textAlign">textAlign</code>, <code
title="dom-context-2d-textBaseline">textBaseline</code>.</li>
</ul>
<p class="note">The current path and the current bitmap are not part
of the drawing state. The current path is persistent, and can only
be reset using the <code
title="dom-context-2d-beginPath">beginPath()</code> method. The
current bitmap is a property of the canvas, not the context.</p>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-save">save</code>()</dt>
<dd>
<p>Pushes the current state onto the stack.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-restore">restore</code>()</dt>
<dd>
<p>Pops the top state on the stack, restoring the context to that state.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-context-2d-save"><code>save()</code></dfn>
method must push a copy of the current drawing state onto the
drawing state stack.</p>
<p>The <dfn
title="dom-context-2d-restore"><code>restore()</code></dfn> method
must pop the top entry in the drawing state stack, and reset the
drawing state it describes. If there is no saved state, the method
must do nothing.</p>
<!-- v4
idea from Mihai:
> 5. Drawing states should be saveable with IDs, and for easier restoring.
>
> save(id)
> restore(id)
>
> If id is not provided, then save() works as defined now. The same for
> restore().
>
> Currently, it's not trivial to save and restore a specific state.
...and from Philip:
> I think a more convenient syntax would be:
> var state = ctx.save();
> ctx.restore(state);
> But how would it interact with normal calls to ctx.restore()?
-->
</div>
<h6><dfn title="dom-context-2d-transformation">Transformations</dfn></h6>
<p>The transformation matrix is applied to coordinates when creating
shapes and paths.</p> <!-- conformance criteria for actual drawing
are described in the various sections below -->
<div class="impl">
<p>When the context is created, the transformation matrix must
initially be the identity transform. It may then be adjusted using
the transformation methods.</p>
<p>The transformations must be performed in reverse order. For
instance, if a scale transformation that doubles the width is
applied, followed by a rotation transformation that rotates drawing
operations by a quarter turn, and a rectangle twice as wide as it is
tall is then drawn on the canvas, the actual result will be a
square.</p>
</div>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-scale">scale</code>(<var title="">x</var>, <var title="">y</var>)</dt>
<dd>
<p>Changes the transformation matrix to apply a scaling transformation with the given characteristics.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-rotate">rotate</code>(<var title="">angle</var>)</dt>
<dd>
<p>Changes the transformation matrix to apply a rotation transformation with the given characteristics. The angle is in radians.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-translate">translate</code>(<var title="">x</var>, <var title="">y</var>)</dt>
<dd>
<p>Changes the transformation matrix to apply a translation transformation with the given characteristics.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-transform">transform</code>(<var title="">m11</var>, <var title="">m12</var>, <var title="">m21</var>, <var title="">m22</var>, <var title="">dx</var>, <var title="">dy</var>)</dt>
<dd>
<p>Changes the transformation matrix to apply the matrix given by the arguments as described below.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-setTransform">setTransform</code>(<var title="">m11</var>, <var title="">m12</var>, <var title="">m21</var>, <var title="">m22</var>, <var title="">dx</var>, <var title="">dy</var>)</dt>
<dd>
<p>Changes the transformation matrix <em>to</em> the matrix given by the arguments as described below.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-context-2d-scale"><code>scale(<var
title="">x</var>, <var title="">y</var>)</code></dfn> method must
add the scaling transformation described by the arguments to the
transformation matrix. The <var title="">x</var> argument represents
the scale factor in the horizontal direction and the <var
title="">y</var> argument represents the scale factor in the
vertical direction. The factors are multiples.</p>
<p>The <dfn title="dom-context-2d-rotate"><code>rotate(<var
title="">angle</var>)</code></dfn> method must add the rotation
transformation described by the argument to the transformation
matrix. The <var title="">angle</var> argument represents a
clockwise rotation angle expressed in radians.</p>
<p>The <dfn title="dom-context-2d-translate"><code>translate(<var
title="">x</var>, <var title="">y</var>)</code></dfn> method must
add the translation transformation described by the arguments to the
transformation matrix. The <var title="">x</var> argument represents
the translation distance in the horizontal direction and the <var
title="">y</var> argument represents the translation distance in the
vertical direction. The arguments are in coordinate space units.</p>
<p>The <dfn title="dom-context-2d-transform"><code>transform(<var
title="">m11</var>, <var title="">m12</var>, <var
title="">m21</var>, <var title="">m22</var>, <var title="">dx</var>,
<var title="">dy</var>)</code></dfn> method must multiply the
current transformation matrix with the matrix described by:</p>
</div>
<table class="matrix">
<tr>
<td><var title="">m11</var></td>
<td><var title="">m21</var></td>
<td><var title="">dx</var></td>
</tr>
<tr>
<td><var title="">m12</var></td>
<td><var title="">m22</var></td>
<td><var title="">dy</var></td>
</tr>
<tr>
<td>0</td>
<td>0</td>
<td>1</td>
</tr>
</table>
<div class="impl">
<p>The <dfn
title="dom-context-2d-setTransform"><code>setTransform(<var
title="">m11</var>, <var title="">m12</var>, <var
title="">m21</var>, <var title="">m22</var>, <var title="">dx</var>,
<var title="">dy</var>)</code></dfn> method must reset the current
transform to the identity matrix, and then invoke the <code><span
title="dom-context-2d-transform">transform</span>(<var
title="">m11</var>, <var title="">m12</var>, <var
title="">m21</var>, <var title="">m22</var>, <var title="">dx</var>,
<var title="">dy</var>)</code> method with the same arguments.</p>
</div>
<h6>Compositing</h6>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-globalAlpha">globalAlpha</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current alpha value applied to rendering operations.</p>
<p>Can be set, to change the alpha value. Values outside of the
range 0.0 .. 1.0 are ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current composition operation, from the list below.</p>
<p>Can be set, to change the composition operation. Unknown values
are ignored.</p>
</dd>
</dl>
<div class="impl">
<p>All drawing operations are affected by the global compositing
attributes, <code
title="dom-context-2d-globalAlpha">globalAlpha</code> and <code
title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</code>.</p>
<!-- conformance criteria for painting are described in the "drawing
model" section below -->
<p>The <dfn
title="dom-context-2d-globalAlpha"><code>globalAlpha</code></dfn>
attribute gives an alpha value that is applied to shapes and images
before they are composited onto the canvas. The value must be in the
range from 0.0 (fully transparent) to 1.0 (no additional
transparency). If an attempt is made to set the attribute to a value
outside this range, including Infinity and Not-a-Number (NaN)
values, the attribute must retain its previous value. When the
context is created, the <code
title="dom-context-2d-globalAlpha">globalAlpha</code> attribute must
initially have the value 1.0.</p>
<p>The <dfn
title="dom-context-2d-globalCompositeOperation"><code>globalCompositeOperation</code></dfn>
attribute sets how shapes and images are drawn onto the existing
bitmap, once they have had <code
title="dom-context-2d-globalAlpha">globalAlpha</code> and the
current transformation matrix applied. It must be set to a value
from the following list. In the descriptions below, the source
image, <var title="">A</var>, is the shape or image being rendered,
and the destination image, <var title="">B</var>, is the current
state of the bitmap.</p>
</div>
<dl>
<dt><dfn title="gcop-source-atop"><code>source-atop</code></dfn></dt>
<dd><var title="">A</var> atop <var title="">B</var>. Display the
source image wherever both images are opaque. Display the
destination image wherever the destination image is opaque but the
source image is transparent. Display transparency elsewhere.</dd>
<dt><dfn title="gcop-source-in"><code>source-in</code></dfn></dt>
<dd><var title="">A</var> in <var title="">B</var>. Display the
source image wherever both the source image and destination image
are opaque. Display transparency elsewhere.</dd>
<dt><dfn title="gcop-source-out"><code>source-out</code></dfn></dt>
<dd><var title="">A</var> out <var title="">B</var>. Display the
source image wherever the source image is opaque and the
destination image is transparent. Display transparency
elsewhere.</dd>
<dt><dfn title="gcop-source-over"><code>source-over</code></dfn> (default)</dt>
<dd><var title="">A</var> over <var title="">B</var>. Display the
source image wherever the source image is opaque. Display the
destination image elsewhere.</dd>
<dt><dfn title="gcop-destination-atop"><code>destination-atop</code></dfn></dt>
<dd><var title="">B</var> atop <var title="">A</var>. Same as <code
title="gcop-source-atop">source-atop</code> but using the
destination image instead of the source image and vice versa.</dd>
<dt><dfn title="gcop-destination-in"><code>destination-in</code></dfn></dt>
<dd><var title="">B</var> in <var title="">A</var>. Same as <code
title="gcop-source-in">source-in</code> but using the destination
image instead of the source image and vice versa.</dd>
<dt><dfn title="gcop-destination-out"><code>destination-out</code></dfn></dt>
<dd><var title="">B</var> out <var title="">A</var>. Same as <code
title="gcop-source-out">source-out</code> but using the destination
image instead of the source image and vice versa.</dd>
<dt><dfn title="gcop-destination-over"><code>destination-over</code></dfn></dt>
<dd><var title="">B</var> over <var title="">A</var>. Same as <code
title="gcop-source-over">source-over</code> but using the
destination image instead of the source image and vice versa.</dd>
<!-- no clear definition of this operator (doesn't correspond to a PorterDuff operator)
<dt><dfn title="gcop-darker"><code>darker</code></dfn></dt>
<dd>Display the sum of the source image and destination image,
with color values approaching 0 as a limit.</dd>
-->
<dt><dfn title="gcop-lighter"><code>lighter</code></dfn></dt>
<dd><var title="">A</var> plus <var title="">B</var>. Display the
sum of the source image and destination image, with color values
approaching 1 as a limit.</dd>
<dt><dfn title="gcop-copy"><code>copy</code></dfn></dt>
<dd><var title="">A</var> (<var title="">B</var> is
ignored). Display the source image instead of the destination
image.</dd>
<dt><dfn title="gcop-xor"><code>xor</code></dfn></dt>
<dd><var title="">A</var> xor <var title="">B</var>. Exclusive OR
of the source image and destination image.</dd>
<dt class="impl"><code><var title="">vendorName</var>-<var title="">operationName</var></code></dt>
<dd class="impl">Vendor-specific extensions to the list of
composition operators should use this syntax.</dd>
</dl>
<div class="impl">
<p>These values are all case-sensitive — they must be used
exactly as shown. User agents must not recognize values that are not
a <span>case-sensitive</span> match for one of the values given
above.</p>
<p>The operators in the above list must be treated as described by
the Porter-Duff operator given at the start of their description
(e.g. <var title="">A</var> over <var title="">B</var>). <a
href="#refsPORTERDUFF">[PORTERDUFF]</a></p>
<p>On setting, if the user agent does not recognize the specified
value, it must be ignored, leaving the value of <code
title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</code>
unaffected.</p>
<p>When the context is created, the <code
title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</code>
attribute must initially have the value
<code>source-over</code>.</p>
</div>
<h6>Colors and styles</h6>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-strokeStyle">strokeStyle</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current style used for stroking shapes.</p>
<p>Can be set, to change the stroke style.</p>
<p>The style can be either a string containing a CSS color, or a
<code>CanvasGradient</code> or <code>CanvasPattern</code>
object. Invalid values are ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-fillStyle">fillStyle</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current style used for filling shapes.</p>
<p>Can be set, to change the fill style.</p>
<p>The style can be either a string containing a CSS color, or a
<code>CanvasGradient</code> or <code>CanvasPattern</code>
object. Invalid values are ignored.</p>
</dd>
</dl>
<div class="impl">
<!-- v4 feature requests:
* Getting and setting colours by component to bypass the CSS value parsing.
Either:
context.fillStyle.red += 1;
Or:
var array = context.fillStyle;
array[1] += 1;
context.fillStyle = array;
* A more performant way of setting colours in general, e.g.:
context.setFillColor(r,g,b,a) // already supported by webkit
Or:
context.fillStyle = 0xRRGGBBAA; // set a 32bit int directly
* fill rule for deciding between winding and even-odd algorithms.
SVG has fill-rule: nonzero | evenodd
http://www.w3.org/TR/SVG/painting.html#FillProperties
-->
<p>The <dfn
title="dom-context-2d-strokeStyle"><code>strokeStyle</code></dfn>
attribute represents the color or style to use for the lines around
shapes, and the <dfn
title="dom-context-2d-fillStyle"><code>fillStyle</code></dfn>
attribute represents the color or style to use inside the
shapes.</p>
<p>Both attributes can be either strings,
<code>CanvasGradient</code>s, or <code>CanvasPattern</code>s. On
setting, strings must be parsed as CSS <color> values and the
color assigned, and <code>CanvasGradient</code> and
<code>CanvasPattern</code> objects must be assigned themselves. <a
href="#refsCSSCOLOR">[CSSCOLOR]</a> If the value is a string but
is not a valid color, or is neither a string, a
<code>CanvasGradient</code>, nor a <code>CanvasPattern</code>, then
it must be ignored, and the attribute must retain its previous
value.</p>
<p>On getting, if the value is a color, then the <span
title="serialization of a color">serialization of the color</span>
must be returned. Otherwise, if it is not a color but a
<code>CanvasGradient</code> or <code>CanvasPattern</code>, then the
respective object must be returned. (Such objects are opaque and
therefore only useful for assigning to other attributes or for
comparison to other gradients or patterns.)</p>
<p>The <dfn>serialization of a color</dfn> for a color value is a
string, computed as follows: if it has alpha equal to 1.0, then the
string is a lowercase six-digit hex value, prefixed with a "#"
character (U+0023 NUMBER SIGN), with the first two digits
representing the red component, the next two digits representing the
green component, and the last two digits representing the blue
component, the digits being in the range 0-9 a-f (U+0030 to U+0039
and U+0061 to U+0066). Otherwise, the color value has alpha less
than 1.0, and the string is the color value in the CSS <code
title="">rgba()</code> functional-notation format: the literal
string <code title="">rgba</code> (U+0072 U+0067 U+0062 U+0061)
followed by a U+0028 LEFT PARENTHESIS, a base-ten integer in the
range 0-255 representing the red component (using digits 0-9, U+0030
to U+0039, in the shortest form possible), a literal U+002C COMMA
and U+0020 SPACE, an integer for the green component, a comma and a
space, an integer for the blue component, another comma and space, a
U+0030 DIGIT ZERO, a U+002E FULL STOP (representing the decimal
point), one or more digits in the range 0-9 (U+0030 to U+0039)
representing the fractional part of the alpha value, and finally a
U+0029 RIGHT PARENTHESIS.</p>
<p>When the context is created, the <code
title="dom-context-2d-strokeStyle">strokeStyle</code> and <code
title="dom-context-2d-fillStyle">fillStyle</code> attributes must
initially have the string value <code title="">#000000</code>.</p>
</div>
<hr>
<p>There are two types of gradients, linear gradients and radial
gradients, both represented by objects implementing the opaque
<code>CanvasGradient</code> interface.</p>
<p id="interpolation">Once a gradient has been created (see below),
stops are placed along it to define how the colors are distributed
along the gradient. <span class="impl">The color of the gradient at
each stop is the color specified for that stop. Between each such
stop, the colors and the alpha component must be linearly
interpolated over the RGBA space without premultiplying the alpha
value to find the color to use at that offset. Before the first
stop, the color must be the color of the first stop. After the last
stop, the color must be the color of the last stop. When there are
no stops, the gradient is transparent black.</span></p>
<dl class="domintro">
<dt><var title="">gradient</var> . <code title="dom-canvasgradient-addColorStop">addColorStop</code>(<var title="">offset</var>, <var title="">color</var>)</dt>
<dd>
<p>Adds a color stop with the given color to the gradient at the
given offset. 0.0 is the offset at one end of the gradient, 1.0 is
the offset at the other end.</p>
<p>Throws an <code>INDEX_SIZE_ERR</code> exception if the offset
it out of range. Throws a <code>SYNTAX_ERR</code> exception if the
color cannot be parsed.</p>
</dd>
<dt><var title="">gradient</var> = <var title="">context</var> . <code title="dom-context-2d-createLinearGradient">createLinearGradient</code>(<var title="">x0</var>, <var title="">y0</var>, <var title="">x1</var>, <var title="">y1</var>)</dt>
<dd>
<p>Returns a <code>CanvasGradient</code> object that represents a
linear gradient that paints along the line given by the
coordinates represented by the arguments.</p>
<p>If any of the arguments are not finite numbers, throws a
<code>NOT_SUPPORTED_ERR</code> exception.</p>
</dd>
<dt><var title="">gradient</var> = <var title="">context</var> . <code title="dom-context-2d-createRadialGradient">createRadialGradient</code>(<var title="">x0</var>, <var title="">y0</var>, <var title="">r0</var>, <var title="">x1</var>, <var title="">y1</var>, <var title="">r1</var>)</dt>
<dd>
<p>Returns a <code>CanvasGradient</code> object that represents a
radial gradient that paints along the cone given by the circles
represented by the arguments.</p>
<p>If any of the arguments are not finite numbers, throws a
<code>NOT_SUPPORTED_ERR</code> exception. If either of the radii
are negative throws an <code>INDEX_SIZE_ERR</code> exception.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-canvasgradient-addColorStop"><code>addColorStop(<var
title="">offset</var>, <var title="">color</var>)</code></dfn>
method on the <code>CanvasGradient</code> interface adds a new stop
to a gradient. If the <var title="">offset</var> is less than 0,
greater than 1, infinite, or NaN, then an
<code>INDEX_SIZE_ERR</code> exception must be raised. If the <var
title="">color</var> cannot be parsed as a CSS color, then a
<code>SYNTAX_ERR</code> exception must be raised. Otherwise, the
gradient must have a new stop placed, at offset <var
title="">offset</var> relative to the whole gradient, and with the
color obtained by parsing <var title="">color</var> as a CSS
<color> value. If multiple stops are added at the same offset
on a gradient, they must be placed in the order added, with the
first one closest to the start of the gradient, and each subsequent
one infinitesimally further along towards the end point (in effect
causing all but the first and last stop added at each point to be
ignored).</p>
<p>The <dfn
title="dom-context-2d-createLinearGradient"><code>createLinearGradient(<var
title="">x0</var>, <var title="">y0</var>, <var title="">x1</var>,
<var title="">y1</var>)</code></dfn> method takes four arguments
that represent the start point (<var title="">x0</var>, <var
title="">y0</var>) and end point (<var title="">x1</var>, <var
title="">y1</var>) of the gradient. If any of the arguments to <code
title="dom-context-2d-createLinearGradient">createLinearGradient()</code>
are infinite or NaN, the method must raise a
<code>NOT_SUPPORTED_ERR</code> exception. Otherwise, the method must
return a linear <code>CanvasGradient</code> initialized with the
specified line.</p>
<p>Linear gradients must be rendered such that all points on a line
perpendicular to the line that crosses the start and end points have
the color at the point where those two lines cross (with the colors
coming from the <a href="#interpolation">interpolation and
extrapolation</a> described above). The points in the linear
gradient must be transformed as described by the <span
title="dom-context-2d-transformation">current transformation
matrix</span> when rendering.</p>
<p>If <span title=""><var title="">x0</var> = <var
title="">x1</var></span> and <span title=""><var
title="">y0</var> = <var title="">y1</var></span>, then
the linear gradient must paint nothing.</p>
<p>The <dfn
title="dom-context-2d-createRadialGradient"><code>createRadialGradient(<var
title="">x0</var>, <var title="">y0</var>, <var title="">r0</var>,
<var title="">x1</var>, <var title="">y1</var>, <var
title="">r1</var>)</code></dfn> method takes six arguments, the
first three representing the start circle with origin (<var
title="">x0</var>, <var title="">y0</var>) and radius <var
title="">r0</var>, and the last three representing the end circle
with origin (<var title="">x1</var>, <var title="">y1</var>) and
radius <var title="">r1</var>. The values are in coordinate space
units. If any of the arguments are infinite or NaN, a
<code>NOT_SUPPORTED_ERR</code> exception must be raised. If either
of <var title="">r0</var> or <var title="">r1</var> are negative, an
<code>INDEX_SIZE_ERR</code> exception must be raised. Otherwise,
the method must return a radial <code>CanvasGradient</code>
initialized with the two specified circles.</p>
<p>Radial gradients must be rendered by following these steps:</p>
<ol>
<li><p>If <span title=""><var
title="">x<sub>0</sub></var> = <var
title="">x<sub>1</sub></var></span> and <span title=""><var
title="">y<sub>0</sub></var> = <var
title="">y<sub>1</sub></var></span> and <span title=""><var
title="">r<sub>0</sub></var> = <var
title="">r<sub>1</sub></var></span>, then the radial gradient must
paint nothing. Abort these steps.</p></li>
<li>
<p>Let <span title="">x(<var
title="">ω</var>) = (<var
title="">x<sub>1</sub></var>-<var
title="">x<sub>0</sub></var>)<var
title="">ω</var> + <var
title="">x<sub>0</sub></var></span></p>
<p>Let <span title="">y(<var
title="">ω</var>) = (<var
title="">y<sub>1</sub></var>-<var
title="">y<sub>0</sub></var>)<var
title="">ω</var> + <var
title="">y<sub>0</sub></var></span></p>
<p>Let <span title="">r(<var
title="">ω</var>) = (<var
title="">r<sub>1</sub></var>-<var
title="">r<sub>0</sub></var>)<var
title="">ω</var> + <var
title="">r<sub>0</sub></var></span></p>
<p>Let the color at <var title="">ω</var> be the color at
that position on the gradient (with the colors coming from the <a
href="#interpolation">interpolation and extrapolation</a>
described above).</p>
</li>
<li><p>For all values of <var title="">ω</var> where <span
title="">r(<var title="">ω</var>) > 0</span>,
starting with the value of <var title="">ω</var> nearest to
positive infinity and ending with the value of <var
title="">ω</var> nearest to negative infinity, draw the
circumference of the circle with radius <span title="">r(<var
title="">ω</var>)</span> at position (<span title="">x(<var
title="">ω</var>)</span>, <span title="">y(<var
title="">ω</var>)</span>), with the color at <var
title="">ω</var>, but only painting on the parts of the
canvas that have not yet been painted on by earlier circles in this
step for this rendering of the gradient.</p></li>
</ol>
<p class="note">This effectively creates a cone, touched by the two
circles defined in the creation of the gradient, with the part of
the cone before the start circle (0.0) using the color of the first
offset, the part of the cone after the end circle (1.0) using the
color of the last offset, and areas outside the cone untouched by
the gradient (transparent black).</p>
<p>Gradients must be painted only where the relevant stroking or
filling effects requires that they be drawn.</p>
<p>The points in the radial gradient must be transformed as
described by the <span title="dom-context-2d-transformation">current
transformation matrix</span> when rendering.</p>
<!--
<p>Support for actually painting gradients is optional. Instead of
painting the gradients, user agents may instead just paint the first
stop's color. However, <code
title="dom-context-2d-createLinearGradient">createLinearGradient()</code>
and <code
title="dom-context-2d-createRadialGradient">createRadialGradient()</code>
must always return objects when passed valid arguments.</p>
-->
</div>
<hr>
<p>Patterns are represented by objects implementing the opaque
<code>CanvasPattern</code> interface.</p>
<dl class="domintro">
<dt><var title="">pattern</var> = <var title="">context</var> . <code title="dom-context-2d-createPattern">createPattern</code>(<var title="">image</var>, <var title="">repetition</var>)</dt>
<dd>
<p>Returns a <code>CanvasPattern</code> object that uses the given image
and repeats in the direction(s) given by the <var
title="">repetition</var> argument.</p>
<p>The allowed values for <code title="">repeat</code> are <code
title="">repeat</code> (both directions), <code
title="">repeat-x</code> (horizontal only), <code
title="">repeat-y</code> (vertical only), and <code
title="">no-repeat</code> (neither). If the <var
title="">repetition</var> argument is empty or null, the value
<code title="">repeat</code> is used.</p>
<p>If the first argument isn't an <code>img</code>,
<code>canvas</code>, or <code>video</code> element, throws a
<code>TYPE_MISMATCH_ERR</code> exception. If the image has no
image data, throws an <code>INVALID_STATE_ERR</code> exception. If
the second argument isn't one of the allowed values, throws a
<code>SYNTAX_ERR</code> exception. If the image isn't yet fully
decoded, then the method returns null.</p>
</dd>
</dl>
<div class="impl">
<p>To create objects of this type, the <dfn
title="dom-context-2d-createPattern"><code>createPattern(<var
title="">image</var>, <var title="">repetition</var>)</code></dfn>
method is used. The first argument gives the image to use as the
pattern (either an <code>HTMLImageElement</code>,
<code>HTMLCanvasElement</code>, or <code>HTMLVideoElement</code>
object). Modifying this image after calling the <code
title="dom-context-2d-createPattern">createPattern()</code> method
must not affect the pattern. The second argument must be a string
with one of the following values: <code title="">repeat</code>,
<code title="">repeat-x</code>, <code title="">repeat-y</code>,
<code title="">no-repeat</code>. If the empty string or null is
specified, <code title="">repeat</code> must be assumed. If an
unrecognized value is given, then the user agent must raise a
<code>SYNTAX_ERR</code> exception. User agents must recognize the
four values described above exactly (e.g. they must not do case
folding). The method must return a <code>CanvasPattern</code> object
suitably initialized.</p>
<p>The <var title="">image</var> argument is an instance of either
<code>HTMLImageElement</code>, <code>HTMLCanvasElement</code>, or
<code>HTMLVideoElement</code>. If the <var title="">image</var> is
of the wrong type or null, the implementation must raise a
<code>TYPE_MISMATCH_ERR</code> exception.</p>
<!-- drawImage() has an equivalent paragraph -->
<p>If the <var title="">image</var> argument is an
<code>HTMLImageElement</code> object whose <code
title="dom-img-complete">complete</code> attribute is false, or
if the <var title="">image</var> argument is an
<code>HTMLVideoElement</code> object whose <code
title="dom-media-readyState">readyState</code> attribute is either
<code title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code> or <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code>, then the
implementation must return null.</p>
<!-- drawImage() has an equivalent paragraph -->
<p>If the <var title="">image</var> argument is an
<code>HTMLCanvasElement</code> object with either a horizontal
dimension or a vertical dimension equal to zero, then the
implementation must raise an <code>INVALID_STATE_ERR</code>
exception.</p>
<!-- drawImage() has an equivalent paragraph -->
<p>Patterns must be painted so that the top left of the first image
is anchored at the origin of the coordinate space, and images are
then repeated horizontally to the left and right (if the
<code>repeat-x</code> string was specified) or vertically up and
down (if the <code>repeat-y</code> string was specified) or in all
four directions all over the canvas (if the <code>repeat</code>
string was specified). The images are not scaled by this process;
one CSS pixel of the image must be painted on one coordinate space
unit. Of course, patterns must actually be painted only where the
stroking or filling effect requires that they be drawn, and are
affected by the current transformation matrix.</p>
<p>When the <code
title="dom-context-2d-createPattern">createPattern()</code> method
is passed an animated image as its <var title="">image</var>
argument, the user agent must use the poster frame of the animation,
or, if there is no poster frame, the first frame of the
animation.</p>
<!-- drawImage() has an equivalent paragraph -->
<p>When the <var title="">image</var> argument is an
<code>HTMLVideoElement</code>, then the frame at the <span>current
playback position</span> must be used as the source image, and the
source image's dimensions must be the <span
title="concept-video-intrinsic-width">intrinsic width</span> and
<span title="concept-video-intrinsic-height">intrinsic height</span>
of the <span>media resource</span> (i.e. after any aspect-ratio
correction has been applied).</p>
<!-- drawImage() has an equivalent paragraph -->
<!--
Requests for v4 features:
* apply transforms to patterns, so you don't have to create
transformed patterns manually by rendering them to an off-screen
canvas then using that canvas as the pattern.
-->
</div>
<h6>Line styles</h6>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-lineWidth">lineWidth</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current line width.</p>
<p>Can be set, to change the line width. Values that are not
finite values greater than zero are ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-lineCap">lineCap</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current line cap style.</p>
<p>Can be set, to change the line cap style.</p>
<p>The possible line cap styles are <code>butt</code>,
<code>round</code>, and <code>square</code>. Other values are
ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-lineJoin">lineJoin</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current line join style.</p>
<p>Can be set, to change the line join style.</p>
<p>The possible line join styles are <code>bevel</code>,
<code>round</code>, and <code>miter</code>. Other values are
ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-miterLimit">miterLimit</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current miter limit ratio.</p>
<p>Can be set, to change the miter limit ratio. Values that are
not finite values greater than zero are ignored.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-context-2d-lineWidth"><code>lineWidth</code></dfn>
attribute gives the width of lines, in coordinate space units. On
getting, it must return the current value. On setting, zero,
negative, infinite, and NaN values must be ignored, leaving the
value unchanged; other values must change the current value to the
new value.</p>
<p>When the context is created, the <code
title="dom-context-2d-lineWidth">lineWidth</code> attribute must
initially have the value <code>1.0</code>.</p>
<hr>
<p>The <dfn
title="dom-context-2d-lineCap"><code>lineCap</code></dfn> attribute
defines the type of endings that UAs will place on the end of
lines. The three valid values are <code>butt</code>,
<code>round</code>, and <code>square</code>. The <code>butt</code>
value means that the end of each line has a flat edge perpendicular
to the direction of the line (and that no additional line cap is
added). The <code>round</code> value means that a semi-circle with
the diameter equal to the width of the line must then be added on to
the end of the line. The <code>square</code> value means that a
rectangle with the length of the line width and the width of half
the line width, placed flat against the edge perpendicular to the
direction of the line, must be added at the end of each line.</p>
<p>On getting, it must return the current value. On setting, if the
new value is one of the literal strings <code>butt</code>,
<code>round</code>, and <code>square</code>, then the current value
must be changed to the new value; other values must ignored, leaving
the value unchanged.</p>
<p>When the context is created, the <code
title="dom-context-2d-lineCap">lineCap</code> attribute must
initially have the value <code>butt</code>.</p>
<hr>
<p>The <dfn
title="dom-context-2d-lineJoin"><code>lineJoin</code></dfn>
attribute defines the type of corners that UAs will place where two
lines meet. The three valid values are <code>bevel</code>,
<code>round</code>, and <code>miter</code>.</p>
<p>On getting, it must return the current value. On setting, if the
new value is one of the literal strings <code>bevel</code>,
<code>round</code>, and <code>miter</code>, then the current value
must be changed to the new value; other values must be ignored,
leaving the value unchanged.</p>
<p>When the context is created, the <code
title="dom-context-2d-lineJoin">lineJoin</code> attribute must
initially have the value <code>miter</code>.</p>
<hr>
<p>A join exists at any point in a subpath shared by two consecutive
lines. When a subpath is closed, then a join also exists at its
first point (equivalent to its last point) connecting the first and
last lines in the subpath.</p>
<p>In addition to the point where the join occurs, two additional
points are relevant to each join, one for each line: the two corners
found half the line width away from the join point, one
perpendicular to each line, each on the side furthest from the other
line.</p>
<p>A filled triangle connecting these two opposite corners with a
straight line, with the third point of the triangle being the join
point, must be rendered at all joins. The <code
title="dom-context-2d-lineJoin">lineJoin</code> attribute controls
whether anything else is rendered. The three aforementioned values
have the following meanings:</p>
<p>The <code>bevel</code> value means that this is all that is
rendered at joins.</p>
<p>The <code>round</code> value means that a filled arc connecting
the two aforementioned corners of the join, abutting (and not
overlapping) the aforementioned triangle, with the diameter equal to
the line width and the origin at the point of the join, must be
rendered at joins.</p>
<p>The <code>miter</code> value means that a second filled triangle
must (if it can given the miter length) be rendered at the join,
with one line being the line between the two aforementioned corners,
abutting the first triangle, and the other two being continuations of
the outside edges of the two joining lines, as long as required to
intersect without going over the miter length.</p>
<p>The miter length is the distance from the point where the join
occurs to the intersection of the line edges on the outside of the
join. The miter limit ratio is the maximum allowed ratio of the
miter length to half the line width. If the miter length would cause
the miter limit ratio to be exceeded, this second triangle must not
be rendered.</p>
<p>The miter limit ratio can be explicitly set using the <dfn
title="dom-context-2d-miterLimit"><code>miterLimit</code></dfn>
attribute. On getting, it must return the current value. On setting,
zero, negative, infinite, and NaN values must be ignored, leaving
the value unchanged; other values must change the current value to
the new value.</p>
<p>When the context is created, the <code
title="dom-context-2d-miterLimit">miterLimit</code> attribute must
initially have the value <code>10.0</code>.</p>
<!--
v4: dashed lines have been requested. Philip Taylor provides these
notes on what would need to be defined for dashed lines:
> I don't think it's entirely trivial to add, to the detail that's
> necessary in a specification. The common graphics APIs (at least
> Cairo, Quartz and java.awt.Graphics, and any SVG implementation) all
> have dashes specified by passing an array of dash lengths (alternating
> on/off), so that should be alright as long as you define what units
> it's measured in and what happens when you specify an odd number of
> values and how errors are handled and what happens if you update the
> array later. But after that, what does it do when stroking multiple
> subpaths, in terms of offsetting the dashes? When you use strokeRect,
> where is offset 0? Does moveTo reset the offset? How does it interact
> with lineCap/lineJoin? All the potential issues need test cases too,
> and the implementations need to make sure they handle any edge cases
> that the underlying graphics library does differently. (SVG Tiny 1.2
> appears to skip some of the problems by leaving things undefined and
> allowing whatever behavior the graphics library has.)
-->
</div>
<h6><dfn>Shadows</dfn></h6>
<p>All drawing operations are affected by the four global shadow
attributes.</p>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-shadowColor">shadowColor</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current shadow color.</p>
<p>Can be set, to change the shadow color. Values that cannot be parsed as CSS colors are ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-shadowOffsetX">shadowOffsetX</code> [ = <var title="">value</var> ]</dt>
<dt><var title="">context</var> . <code title="dom-context-2d-shadowOffsetY">shadowOffsetY</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current shadow offset.</p>
<p>Can be set, to change the shadow offset. Values that are not finite numbers are ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-shadowBlur">shadowBlur</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current level of blur applied to shadows.</p>
<p>Can be set, to change the blur level. Values that are not finite numbers greater than or equal to zero are ignored.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-context-2d-shadowColor"><code>shadowColor</code></dfn>
attribute sets the color of the shadow.</p>
<p>When the context is created, the <code
title="dom-context-2d-shadowColor">shadowColor</code> attribute
initially must be fully-transparent black.</p>
<p>On getting, the <span title="serialization of a
color">serialization of the color</span> must be returned.</p>
<p>On setting, the new value must be parsed as a CSS <color>
value and the color assigned. If the value is not a valid color,
then it must be ignored, and the attribute must retain its previous
value. <a href="#refsCSSCOLOR">[CSSCOLOR]</a></p>
<p>The <dfn
title="dom-context-2d-shadowOffsetX"><code>shadowOffsetX</code></dfn>
and <dfn
title="dom-context-2d-shadowOffsetY"><code>shadowOffsetY</code></dfn>
attributes specify the distance that the shadow will be offset in
the positive horizontal and positive vertical distance
respectively. Their values are in coordinate space units. They are
not affected by the current transformation matrix.</p>
<p>When the context is created, the shadow offset attributes must
initially have the value <code>0</code>.</p>
<p>On getting, they must return their current value. On setting, the
attribute being set must be set to the new value, except if the
value is infinite or NaN, in which case the new value must be
ignored.</p>
<p>The <dfn
title="dom-context-2d-shadowBlur"><code>shadowBlur</code></dfn>
attribute specifies the size of the blurring effect. (The units do
not map to coordinate space units, and are not affected by the
current transformation matrix.)</p>
<p>When the context is created, the <code
title="dom-context-2d-shadowBlur">shadowBlur</code> attribute must
initially have the value <code>0</code>.</p>
<p>On getting, the attribute must return its current value. On
setting the attribute must be set to the new value, except if the
value is negative, infinite or NaN, in which case the new value must
be ignored.</p>
<p><dfn title="when shadows are drawn">Shadows are only drawn
if</dfn> the opacity component of the alpha component of the color
of <code title="dom-context-2d-shadowColor">shadowColor</code> is
non-zero and either the <code
title="dom-context-2d-shadowBlur">shadowBlur</code> is non-zero, or
the <code title="dom-context-2d-shadowOffsetX">shadowOffsetX</code>
is non-zero, or the <code
title="dom-context-2d-shadowOffsetY">shadowOffsetY</code> is
non-zero.</p>
<p><span>When shadows are drawn</span>, they must be rendered as follows:</p>
<ol>
<li> <p>Let <var title="">A</var> be an infinite transparent black
bitmap on which the source image for which a shadow is being
created has been rendered.</p> </li>
<li> <p>Let <var title="">B</var> be an infinite transparent black
bitmap, with a coordinate space and an origin identical to <var
title="">A</var>.</p> </li>
<li> <p>Copy the alpha channel of <var title="">A</var> to <var
title="">B</var>, offset by <code
title="dom-context-2d-shadowOffsetX">shadowOffsetX</code> in the
positive <var title="">x</var> direction, and <code
title="dom-context-2d-shadowOffsetY">shadowOffsetY</code> in the
positive <var title="">y</var> direction.</p> </li>
<li> <p>If <code
title="dom-context-2d-shadowBlur">shadowBlur</code> is greater than
0:</p>
<ol>
<li> <p>If <code
title="dom-context-2d-shadowBlur">shadowBlur</code> is less than
8, let <var title="">σ</var> be half the value of <code
title="dom-context-2d-shadowBlur">shadowBlur</code>; otherwise,
let <var title="">σ</var> be the square root of multiplying
the value of <code
title="dom-context-2d-shadowBlur">shadowBlur</code> by
2.</p></li>
<li> <p>Perform a 2D Gaussian Blur on <var title="">B</var>,
using <var title="">σ</var> as the standard deviation.</p>
<!-- wish i could find a reference for this --> </li>
</ol>
<p>User agents may limit values of <var title="">σ</var> to
an implementation-specific maximum value to avoid exceeding
hardware limitations during the Gaussian blur operation.</p>
</li>
<li> <p>Set the red, green, and blue components of every pixel in
<var title="">B</var> to the red, green, and blue components
(respectively) of the color of <code
title="dom-context-2d-shadowColor">shadowColor</code>.</p> </li>
<li> <p>Multiply the alpha component of every pixel in <var
title="">B</var> by the alpha component of the color of <code
title="dom-context-2d-shadowColor">shadowColor</code>.</p> </li>
<li> <p>The shadow is in the bitmap <var title="">B</var>, and is
rendered as part of the drawing model described below.</p> </li>
</ol>
</div>
<p>If the current composition operation is <code
title="gcop-copy">copy</code>, shadows effectively won't render
(since the shape will overwrite the shadow).</p>
<h6>Simple shapes (rectangles)</h6>
<p>There are three methods that immediately draw rectangles to the
bitmap. They each take four arguments; the first two give the <var
title="">x</var> and <var title="">y</var> coordinates of the top
left of the rectangle, and the second two give the width <var
title="">w</var> and height <var title="">h</var> of the rectangle,
respectively.</p>
<div class="impl">
<p>The <span title="dom-context-2d-transformation">current
transformation matrix</span> must be applied to the following four
coordinates, which form the path that must then be closed to get the
specified rectangle: <span title="">(<var title="">x</var>, <var
title="">y</var>)</span>, <span title="">(<span title=""><var title="">x</var>+<var
title="">w</var></span>, <var title="">y</var>)</span>,
<span title="">(<span title=""><var title="">x</var>+<var title="">w</var></span>,
<span title=""><var title="">y</var>+<var title="">h</var></span>)</span>,
<span title="">(<var title="">x</var>, <span title=""><var title="">y</var>+<var
title="">h</var></span>)</span>.</p>
<p>Shapes are painted without affecting the current path, and are
subject to the <span title="clipping region">clipping region</span>,
and, with the exception of <code
title="dom-context-2d-clearRect">clearRect()</code>, also <span
title="shadows">shadow effects</span>, <span
title="dom-context-2d-globalAlpha">global alpha</span>, and <span
title="dom-context-2d-globalCompositeOperation">global composition
operators</span>.</p>
</div>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-clearRect">clearRect</code>(<var title="">x</var>, <var title="">y</var>, <var title="">w</var>, <var title="">h</var>)</dt>
<dd>
<p>Clears all pixels on the canvas in the given rectangle to transparent black.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-fillRect">fillRect</code>(<var title="">x</var>, <var title="">y</var>, <var title="">w</var>, <var title="">h</var>)</dt>
<dd>
<p>Paints the given rectangle onto the canvas, using the current fill style.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-strokeRect">strokeRect</code>(<var title="">x</var>, <var title="">y</var>, <var title="">w</var>, <var title="">h</var>)</dt>
<dd>
<p>Paints the box that outlines the given rectangle onto the canvas, using the current stroke style.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-context-2d-clearRect"><code>clearRect(<var
title="">x</var>, <var title="">y</var>, <var title="">w</var>, <var
title="">h</var>)</code></dfn> method must clear the pixels in the
specified rectangle that also intersect the current clipping region
to a fully transparent black, erasing any previous image. If either
height or width are zero, this method has no effect.</p>
<p>The <dfn title="dom-context-2d-fillRect"><code>fillRect(<var
title="">x</var>, <var title="">y</var>, <var title="">w</var>, <var
title="">h</var>)</code></dfn> method must paint the specified
rectangular area using the <code
title="dom-context-2d-fillStyle">fillStyle</code>. If either height
or width are zero, this method has no effect.</p>
<p>The <dfn title="dom-context-2d-strokeRect"><code>strokeRect(<var
title="">x</var>, <var title="">y</var>, <var title="">w</var>, <var
title="">h</var>)</code></dfn> method must stroke the specified
rectangle's path using the <code
title="dom-context-2d-strokeStyle">strokeStyle</code>, <code
title="dom-context-2d-lineWidth">lineWidth</code>, <code
title="dom-context-2d-lineJoin">lineJoin</code>, and (if
appropriate) <code
title="dom-context-2d-miterLimit">miterLimit</code> attributes. If
both height and width are zero, this method has no effect, since
there is no path to stroke (it's a point). If only one of the two is
zero, then the method will draw a line instead (the path for the
outline is just a straight line along the non-zero dimension).</p>
</div>
<h6>Complex shapes (paths)</h6>
<p>The context always has a current path. There is only one current
path, it is not part of the <span>drawing state</span>.</p>
<p>A <dfn>path</dfn> has a list of zero or more subpaths. Each
subpath consists of a list of one or more points, connected by
straight or curved lines, and a flag indicating whether the subpath
is closed or not. A closed subpath is one where the last point of
the subpath is connected to the first point of the subpath by a
straight line. Subpaths with fewer than two points are ignored when
painting the path.</p>
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-beginPath">beginPath</code>()</dt>
<dd>
<p>Resets the current path.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-moveTo">moveTo</code>(<var title="">x</var>, <var title="">y</var>)</dt>
<dd>
<p>Creates a new subpath with the given point.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-closePath">closePath</code>()</dt>
<dd>
<p>Marks the current subpath as closed, and starts a new subpath with a point the same as the start and end of the newly closed subpath.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-lineTo">lineTo</code>(<var title="">x</var>, <var title="">y</var>)</dt>
<dd>
<p>Adds the given point to the current subpath, connected to the previous one by a straight line.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-quadraticCurveTo">quadraticCurveTo</code>(<var title="">cpx</var>, <var title="">cpy</var>, <var title="">x</var>, <var title="">y</var>)</dt>
<dd>
<p>Adds the given point to the current path, connected to the previous one by a quadratic Bézier curve with the given control point.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-bezierCurveTo">bezierCurveTo</code>(<var title="">cp1x</var>, <var title="">cp1y</var>, <var title="">cp2x</var>, <var title="">cp2y</var>, <var title="">x</var>, <var title="">y</var>)</dt>
<dd>
<p>Adds the given point to the current path, connected to the previous one by a cubic Bézier curve with the given control points.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-arcTo">arcTo</code>(<var title="">x1</var>, <var title="">y1</var>, <var title="">x2</var>, <var title="">y2</var>, <var title="">radius</var>)</dt>
<dd>
<p>Adds a point to the current path, connected to the previous one
by a straight line, then adds a second point to the current path,
connected to the previous one by an arc whose properties are
described by the arguments.</p>
<p>Throws an <code>INDEX_SIZE_ERR</code> exception if the given
radius is negative.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-arc">arc</code>(<var title="">x</var>, <var title="">y</var>, <var title="">radius</var>, <var title="">startAngle</var>, <var title="">endAngle</var>, <var title="">anticlockwise</var>)</dt>
<dd>
<p>Adds points to the subpath such that the arc described by the
circumference of the circle described by the arguments, starting
at the given start angle and ending at the given end angle, going
in the given direction, is added to the path, connected to the
previous point by a straight line.</p>
<p>Throws an <code>INDEX_SIZE_ERR</code> exception if the given
radius is negative.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-rect">rect</code>(<var title="">x</var>, <var title="">y</var>, <var title="">w</var>, <var title="">h</var>)</dt>
<dd>
<p>Adds a new closed subpath to the path, representing the given rectangle.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-fill">fill</code>()</dt>
<dd>
<p>Fills the subpaths with the current fill style.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-stroke">stroke</code>()</dt>
<dd>
<p>Strokes the subpaths with the current stroke style.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-clip">clip</code>()</dt>
<dd>
<p>Further constrains the clipping region to the given path.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-isPointInPath">isPointInPath</code>(<var title="">x</var>, <var title="">y</var>)</dt>
<dd>
<p>Returns true if the given point is in the current path.</p>
</dd>
</dl>
<div class="impl">
<p>Initially, the context's path must have zero subpaths.</p>
<p>The points and lines added to the path by these methods must be
transformed according to the <span
title="dom-context-2d-transformation">current transformation
matrix</span> as they are added.</p>
<p>The <dfn
title="dom-context-2d-beginPath"><code>beginPath()</code></dfn>
method must empty the list of subpaths so that the context once
again has zero subpaths.</p>
<p>The <dfn title="dom-context-2d-moveTo"><code>moveTo(<var
title="">x</var>, <var title="">y</var>)</code></dfn> method must
create a new subpath with the specified point as its first (and
only) point.</p>
<p>When the user agent is to <dfn>ensure there is a subpath</dfn>
for a coordinate (<var title="">x</var>, <var title="">y</var>), the
user agent must check to see if the context has any subpaths, and if
it does not, then the user agent must create a new subpath with the
point (<var title="">x</var>, <var title="">y</var>) as its first
(and only) point, as if the <code
title="dom-context-2d-moveTo">moveTo()</code> method had been
called.</p>
<p>The <dfn
title="dom-context-2d-closePath"><code>closePath()</code></dfn>
method must do nothing if the context has no subpaths. Otherwise, it
must mark the last subpath as closed, create a new subpath whose
first point is the same as the previous subpath's first point, and
finally add this new subpath to the path.</p>
<p class="note">If the last subpath had more than one point in its
list of points, then this is equivalent to adding a straight line
connecting the last point back to the first point, thus "closing"
the shape, and then repeating the last (possibly implied) <code
title="dom-context-2d-moveTo">moveTo()</code> call.</p>
<p>New points and the lines connecting them are added to subpaths
using the methods described below. In all cases, the methods only
modify the last subpath in the context's paths.</p>
<p>The <dfn title="dom-context-2d-lineTo"><code>lineTo(<var
title="">x</var>, <var title="">y</var>)</code></dfn> method must
<span>ensure there is a subpath</span> for <span title="">(<var
title="">x</var>, <var title="">y</var>)</span> if the context has
no subpaths. Otherwise, it must connect the last point in the
subpath to the given point (<var title="">x</var>, <var
title="">y</var>) using a straight line, and must then add the given
point (<var title="">x</var>, <var title="">y</var>) to the
subpath.</p>
<p>The <dfn
title="dom-context-2d-quadraticCurveTo"><code>quadraticCurveTo(<var
title="">cpx</var>, <var title="">cpy</var>, <var title="">x</var>,
<var title="">y</var>)</code></dfn> method must <span>ensure there
is a subpath</span> for <span title="">(<var title="">cpx</var>,
<var title="">cpy</var>)</span>, and then must connect the last
point in the subpath to the given point (<var title="">x</var>, <var
title="">y</var>) using a quadratic Bézier curve with control
point (<var title="">cpx</var>, <var title="">cpy</var>), and must
then add the given point (<var title="">x</var>, <var
title="">y</var>) to the subpath. <a
href="#refsBEZIER">[BEZIER]</a></p>
<p>The <dfn
title="dom-context-2d-bezierCurveTo"><code>bezierCurveTo(<var
title="">cp1x</var>, <var title="">cp1y</var>, <var
title="">cp2x</var>, <var title="">cp2y</var>, <var
title="">x</var>, <var title="">y</var>)</code></dfn> method must
<span>ensure there is a subpath</span> for <span title="">(<var
title="">cp1x</var>, <var title="">cp1y</var>)</span>, and then must
connect the last point in the subpath to the given point (<var
title="">x</var>, <var title="">y</var>) using a cubic Bézier
curve with control points (<var title="">cp1x</var>, <var
title="">cp1y</var>) and (<var title="">cp2x</var>, <var
title="">cp2y</var>). Then, it must add the point (<var
title="">x</var>, <var title="">y</var>) to the subpath. <a
href="#refsBEZIER">[BEZIER]</a></p>
<hr>
<p>The <dfn title="dom-context-2d-arcTo"><code>arcTo(<var
title="">x1</var>, <var title="">y1</var>, <var title="">x2</var>,
<var title="">y2</var>, <var title="">radius</var>)</code></dfn>
method must first <span>ensure there is a subpath</span> for <span
title="">(<var title="">x1</var>, <var
title="">y1</var>)</span>. Then, the behavior depends on the
arguments and the last point in the subpath, as described below.</p>
<p>Negative values for <var title="">radius</var> must cause the
implementation to raise an <code>INDEX_SIZE_ERR</code>
exception.</p>
<p>Let the point (<var title="">x0</var>, <var title="">y0</var>) be
the last point in the subpath.</p>
<p>If the point (<var title="">x0</var>, <var title="">y0</var>) is
equal to the point (<var title="">x1</var>, <var title="">y1</var>),
or if the point (<var title="">x1</var>, <var title="">y1</var>) is
equal to the point (<var title="">x2</var>, <var title="">y2</var>),
or if the radius <var title="">radius</var> is zero, then the method
must add the point (<var title="">x1</var>, <var title="">y1</var>)
to the subpath, and connect that point to the previous point (<var
title="">x0</var>, <var title="">y0</var>) by a straight line.</p>
<p>Otherwise, if the points (<var title="">x0</var>, <var
title="">y0</var>), (<var title="">x1</var>, <var
title="">y1</var>), and (<var title="">x2</var>, <var
title="">y2</var>) all lie on a single straight line, then the
method must add the point (<var title="">x1</var>, <var
title="">y1</var>) to the subpath, and connect that point to the
previous point (<var title="">x0</var>, <var title="">y0</var>) by a
straight line.</p>
<p>Otherwise, let <var title="">The Arc</var> be the shortest arc
given by circumference of the circle that has radius <var
title="">radius</var>, and that has one point tangent to the
half-infinite line that crosses the point (<var title="">x0</var>,
<var title="">y0</var>) and ends at the point (<var
title="">x1</var>, <var title="">y1</var>), and that has a different
point tangent to the half-infinite line that ends at the point (<var
title="">x1</var>, <var title="">y1</var>) and crosses the point
(<var title="">x2</var>, <var title="">y2</var>). The points at
which this circle touches these two lines are called the start and
end tangent points respectively. The method must connect the point
(<var title="">x0</var>, <var title="">y0</var>) to the start
tangent point by a straight line, adding the start tangent point to
the subpath, and then must connect the start tangent point to the
end tangent point by <var title="">The Arc</var>, adding the end
tangent point to the subpath.</p>
<hr>
<p>The <dfn title="dom-context-2d-arc"><code>arc(<var
title="">x</var>, <var title="">y</var>, <var title="">radius</var>,
<var title="">startAngle</var>, <var title="">endAngle</var>, <var
title="">anticlockwise</var>)</code></dfn> method draws an arc. If
the context has any subpaths, then the method must add a straight
line from the last point in the subpath to the start point of the
arc. In any case, it must draw the arc between the start point of
the arc and the end point of the arc, and add the start and end
points of the arc to the subpath. The arc and its start and end
points are defined as follows:</p>
<p>Consider a circle that has its origin at (<var title="">x</var>,
<var title="">y</var>) and that has radius <var
title="">radius</var>. The points at <var title="">startAngle</var>
and <var title="">endAngle</var> along this circle's circumference,
measured in radians clockwise from the positive x-axis, are the
start and end points respectively.</p>
<p>If the <var title="">anticlockwise</var> argument is false and
<span title=""><var title="">endAngle</var>-<var
title="">startAngle</var></span> is equal to or greater than
<span title="">2π</span>, or, if the <var title="">anticlockwise</var>
argument is <em>true</em> and <span title=""><var
title="">startAngle</var>-<var title="">endAngle</var></span> is
equal to or greater than <span title="">2π</span>, then the arc is the
whole circumference of this circle.</p>
<!--alternatively (this is not equivalent, but might make more
sense, if browsers are willing to change to it: <p>If the absolute
magnitude of the difference between the <var
title="">startAngle</var> and <var title="">endAngle</var> angles is
equal to or greater than <span title="">2π</span>, then the arc is the
whole circumference of this circle.</p>-->
<p>Otherwise, the arc is the path along the circumference of this
circle from the start point to the end point, going anti-clockwise
if the <var title="">anticlockwise</var> argument is true, and
clockwise otherwise. Since the points are on the circle, as opposed
to being simply angles from zero, the arc can never cover an angle
greater than <span title="">2π</span> radians. If the two points are the
same, or if the radius is zero, then the arc is defined as being of
zero length in both directions.</p>
<p>Negative values for <var title="">radius</var> must cause the
implementation to raise an <code>INDEX_SIZE_ERR</code>
exception.</p>
<hr>
<p>The <dfn title="dom-context-2d-rect"><code>rect(<var
title="">x</var>, <var title="">y</var>, <var title="">w</var>, <var
title="">h</var>)</code></dfn> method must create a new subpath
containing just the four points (<var title="">x</var>, <var
title="">y</var>), (<var title="">x</var>+<var title="">w</var>,
<var title="">y</var>), (<var title="">x</var>+<var
title="">w</var>, <var title="">y</var>+<var title="">h</var>),
(<var title="">x</var>, <var title="">y</var>+<var
title="">h</var>), with those four points connected by straight
lines, and must then mark the subpath as closed. It must then create
a new subpath with the point (<var title="">x</var>, <var
title="">y</var>) as the only point in the subpath.</p>
<!-- v4 feature request:
* points as a primitive shape
http://home.comcast.net/~urbanjost/canvas/vogle4.html
-->
<p>The <dfn title="dom-context-2d-fill"><code>fill()</code></dfn>
method must fill all the subpaths of the current path, using
<code title="dom-context-2d-fillStyle">fillStyle</code>, and using
the non-zero winding number rule. Open subpaths must be implicitly
closed when being filled (without affecting the actual
subpaths).</p>
<p class="note">Thus, if two overlapping but otherwise independent
subpaths have opposite windings, they cancel out and result in no
fill. If they have the same winding, that area just gets painted
once.</p>
<p>The <dfn
title="dom-context-2d-stroke"><code>stroke()</code></dfn> method
must calculate the strokes of all the subpaths of the current path,
using the <code title="dom-context-2d-lineWidth">lineWidth</code>,
<code title="dom-context-2d-lineCap">lineCap</code>, <code
title="dom-context-2d-lineJoin">lineJoin</code>, and (if
appropriate) <code
title="dom-context-2d-miterLimit">miterLimit</code> attributes, and
then fill the combined stroke area using the <code
title="dom-context-2d-strokeStyle">strokeStyle</code>
attribute.</p>
<p class="note">Since the subpaths are all stroked as one,
overlapping parts of the paths in one stroke operation are treated
as if their union was what was painted.</p>
<p>Paths, when filled or stroked, must be painted without affecting
the current path, and must be subject to <span
title="shadows">shadow effects</span>, <span
title="dom-context-2d-globalAlpha">global alpha</span>, the <span
title="clipping region">clipping region</span>, and <span
title="dom-context-2d-globalCompositeOperation">global composition
operators</span>. (Transformations affect the path when the path is
created, not when it is painted, though the stroke <em>style</em> is
still affected by the transformation during painting.)</p>
<p>Zero-length line segments must be pruned before stroking a
path. Empty subpaths must be ignored.</p>
<p>The <dfn title="dom-context-2d-clip"><code>clip()</code></dfn>
method must create a new <dfn>clipping region</dfn> by calculating
the intersection of the current clipping region and the area
described by the current path, using the non-zero winding number
rule. Open subpaths must be implicitly closed when computing the
clipping region, without affecting the actual subpaths. The new
clipping region replaces the current clipping region.</p>
<p>When the context is initialized, the clipping region must be set
to the rectangle with the top left corner at (0,0) and the width and
height of the coordinate space.</p>
<!-- v4
Jordan OSETE suggests:
* support ways of extending the clipping region (union instead of intersection)
- also "add", "subtract", "replace", "intersect" and "xor"
* support ways of resetting the clipping region without save/restore
-->
<p>The <dfn
title="dom-context-2d-isPointInPath"><code>isPointInPath(<var
title="">x</var>, <var title="">y</var>)</code></dfn> method must
return true if the point given by the <var title="">x</var> and <var
title="">y</var> coordinates passed to the method, when treated as
coordinates in the canvas coordinate space unaffected by the current
transformation, is inside the current path as determined by the
non-zero winding number rule; and must return false
otherwise. Points on the path itself are considered to be inside the
path. If either of the arguments is infinite or NaN, then the method
must return false.</p>
</div>
<h6>Text</h6> <!-- a v3 feature -->
<dl class="domintro">
<dt><var title="">context</var> . <code title="dom-context-2d-font">font</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current font settings.</p>
<p>Can be set, to change the font. The syntax is the same as for
the CSS 'font' property; values that cannot be parsed as CSS font
values are ignored.</p>
<p>Relative keywords and lengths are computed relative to the font
of the <code>canvas</code> element.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-textAlign">textAlign</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current text alignment settings.</p>
<p>Can be set, to change the alignment. The possible values are
<code title="">start</code>, <code title="">end</code>, <code
title="">left</code>, <code title="">right</code>, and <code
title="">center</code>. The default is <code
title="">start</code>. Other values are ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-textBaseline">textBaseline</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current baseline alignment settings.</p>
<p>Can be set, to change the baseline alignment. The possible
values and their meanings are given below. The default is <code
title="">alphabetic</code>. Other values are ignored.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-fillText">fillText</code>(<var title="">text</var>, <var title="">x</var>, <var title="">y</var> [, <var title="">maxWidth</var> ] )</dt>
<dt><var title="">context</var> . <code title="dom-context-2d-strokeText">strokeText</code>(<var title="">text</var>, <var title="">x</var>, <var title="">y</var> [, <var title="">maxWidth</var> ] )</dt>
<dd>
<p>Fills or strokes (respectively) the given text at the given
position. If a maximum width is provided, the text will be scaled
to fit that width if necessary.</p>
</dd>
<dt><var title="">metrics</var> = <var title="">context</var> . <code title="dom-context-2d-measureText">measureText</code>(<var title="">text</var>)</dt>
<dd>
<p>Returns a <code>TextMetrics</code> object with the metrics of the given text in the current font.</p>
</dd>
<dt><var title="">metrics</var> . <code title="dom-textmetrics-width">width</code></dt>
<dd>
<p>Returns the advance width of the text that was passed to the
<code title="dom-context-2d-measureText">measureText()</code>
method.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-context-2d-font"><code>font</code></dfn> IDL
attribute, on setting, must be parsed the same way as the 'font'
property of CSS (but without supporting property-independent style
sheet syntax like 'inherit'), and the resulting font must be
assigned to the context, with the 'line-height' component forced to
'normal', with the 'font-size' component converted to CSS pixels,
and with system fonts being computed to explicit values. If the new
value is syntactically incorrect (including using
property-independent style sheet syntax like 'inherit' or
'initial'), then it must be ignored, without assigning a new font
value. <a href="#refsCSS">[CSS]</a></p>
<p>Font names must be interpreted in the context of the
<code>canvas</code> element's stylesheets; any fonts embedded using
<code title="">@font-face</code> must therefore be available once
they are loaded. (If a font is referenced before it is fully loaded,
then it must be treated as if it was an unknown font, falling back
to another as described by the relevant CSS specifications.) <a
href="#refsCSSFONTS">[CSSFONTS]</a></p>
<p>Only vector fonts should be used by the user agent; if a user
agent were to use bitmap fonts then transformations would likely
make the font look very ugly.</p>
<p>On getting, the <code title="dom-context-2d-font">font</code>
attribute must return the <span title="serializing a CSS
value">serialized form</span> of the current font of the context
(with no 'line-height' component). <a
href="#refsCSSOM">[CSSOM]</a></p>
<div class="example">
<p>For example, after the following statement:</p>
<pre>context.font = 'italic 400 12px/2 Unknown Font, sans-serif';</pre>
<p>...the expression <code title="">context.font</code> would
evaluate to the string "<code
title="">italic 12px "Unknown Font", sans-serif</code>". The
"400" font-weight doesn't appear because that is the default
value. The line-height doesn't appear because it is forced to
"normal", the default value.</p>
</div>
<p>When the context is created, the font of the context must be set
to 10px sans-serif. When the 'font-size' component is set to lengths
using percentages, 'em' or 'ex' units, or the 'larger' or 'smaller'
keywords, these must be interpreted relative to the computed value
of the 'font-size' property of the corresponding <code>canvas</code>
element at the time that the attribute is set. When the
'font-weight' component is set to the relative values 'bolder' and
'lighter', these must be interpreted relative to the computed value
of the 'font-weight' property of the corresponding
<code>canvas</code> element at the time that the attribute is
set. If the computed values are undefined for a particular case
(e.g. because the <code>canvas</code> element is not <span>in a
<code>Document</code></span>), then the relative keywords must be
interpreted relative to the normal-weight 10px sans-serif
default.</p>
<p>The <dfn
title="dom-context-2d-textAlign"><code>textAlign</code></dfn> IDL
attribute, on getting, must return the current value. On setting, if
the value is one of <code title="">start</code>, <code
title="">end</code>, <code title="">left</code>, <code
title="">right</code>, or <code title="">center</code>, then the
value must be changed to the new value. Otherwise, the new value
must be ignored. When the context is created, the <code
title="dom-context-2d-textAlign">textAlign</code> attribute must
initially have the value <code title="">start</code>.</p>
<p>The <dfn
title="dom-context-2d-textBaseline"><code>textBaseline</code></dfn>
IDL attribute, on getting, must return the current value. On
setting, if the value is one of <code
title="dom-context-2d-textBaseline-top">top</code>, <code
title="dom-context-2d-textBaseline-hanging">hanging</code>, <code
title="dom-context-2d-textBaseline-middle">middle</code>, <code
title="dom-context-2d-textBaseline-alphabetic">alphabetic</code>,
<code
title="dom-context-2d-textBaseline-ideographic">ideographic</code>,
or <code title="dom-context-2d-textBaseline-bottom">bottom</code>,
then the value must be changed to the new value. Otherwise, the new
value must be ignored. When the context is created, the <code
title="dom-context-2d-textBaseline">textBaseline</code> attribute
must initially have the value <code title="">alphabetic</code>.</p>
</div>
<p>The <code title="dom-context-2d-textBaseline">textBaseline</code>
attribute's allowed keywords correspond to alignment points in the
font:</p>
<p><img src="images/baselines.png" alt="The top of the em square is
roughly at the top of the glyphs in a font, the hanging baseline is
where some glyphs like आ are anchored, the middle is half-way
between the top of the em square and the bottom of the em square,
the alphabetic baseline is where characters like Á, ÿ,
f, and Ω are anchored, the ideographic baseline is
where glyphs like 私 and 達 are anchored, and the bottom
of the em square is roughly at the bottom of the glyphs in a
font. The top and bottom of the bounding box can be far from these
baselines, due to glyphs extending far outside the em square."></p>
<p>The keywords map to these alignment points as follows:</p>
<dl>
<dt><dfn title="dom-context-2d-textBaseline-top"><code>top</code></dfn>
<dd>The top of the em square</dd>
<dt><dfn title="dom-context-2d-textBaseline-hanging"><code>hanging</code></dfn>
<dd>The hanging baseline</dd>
<dt><dfn title="dom-context-2d-textBaseline-middle"><code>middle</code></dfn>
<dd>The middle of the em square</dd>
<dt><dfn title="dom-context-2d-textBaseline-alphabetic"><code>alphabetic</code></dfn>
<dd>The alphabetic baseline</dd>
<dt><dfn title="dom-context-2d-textBaseline-ideographic"><code>ideographic</code></dfn>
<dd>The ideographic baseline</dd>
<dt><dfn title="dom-context-2d-textBaseline-bottom"><code>bottom</code></dfn>
<dd>The bottom of the em square</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-context-2d-fillText"><code>fillText()</code></dfn> and
<dfn
title="dom-context-2d-strokeText"><code>strokeText()</code></dfn>
methods take three or four arguments, <var title="">text</var>, <var
title="">x</var>, <var title="">y</var>, and optionally <var
title="">maxWidth</var>, and render the given <var
title="">text</var> at the given (<var title="">x</var>, <var
title="">y</var>) coordinates ensuring that the text isn't wider
than <var title="">maxWidth</var> if specified, using the current
<code title="dom-context-2d-font">font</code>, <code
title="dom-context-2d-textAlign">textAlign</code>, and <code
title="dom-context-2d-textBaseline">textBaseline</code>
values. Specifically, when the methods are called, the user agent
must run the following steps:</p>
<ol>
<li><p>Let <var title="">font</var> be the current font of the
context, as given by the <code
title="dom-context-2d-font">font</code> attribute.</p></li>
<li><p>Replace all the <span title="space character">space
characters</span> in <var title="">text</var> with U+0020 SPACE
characters.</p></li>
<li><p>Form a hypothetical infinitely wide CSS line box containing
a single inline box containing the text <var title="">text</var>,
with all the properties at their initial values except the 'font'
property of the inline box set to <var title="">font</var> and the
'direction' property of the inline box set to <span>the
directionality</span> of the <code>canvas</code> element. <a
href="#refsCSS">[CSS]</a></p></li>
<!-- if you insert a step here, make sure to adjust the next step's
final words -->
<li><p>If the <var title="">maxWidth</var> argument was specified
and the hypothetical width of the inline box in the hypothetical
line box is greater than <var title="">maxWidth</var> CSS pixels,
then change <var title="">font</var> to have a more condensed font
(if one is available or if a reasonably readable one can be
synthesized by applying a horizontal scale factor to the font) or a
smaller font, and return to the previous step.</p></li>
<li>
<p>Let the <var title="">anchor point</var> be a point on the
inline box, determined by the <code
title="dom-context-2d-textAlign">textAlign</code> and <code
title="dom-context-2d-textBaseline">textBaseline</code> values, as
follows:</p>
<p>Horizontal position:</p>
<dl>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">left</code></dt>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">start</code> and <span>the directionality</span> of the
<code>canvas</code> element is 'ltr'</dt>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">end</code> and <span>the directionality</span> of the
<code>canvas</code> element is 'rtl'</dt>
<dd>Let the <var title="">anchor point</var>'s horizontal
position be the left edge of the inline box.</dd>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">right</code></dt>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">end</code> and <span>the directionality</span> of the
<code>canvas</code> element is 'ltr'</dt>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">start</code> and <span>the directionality</span> of the
<code>canvas</code> element is 'rtl'</dt>
<dd>Let the <var title="">anchor point</var>'s horizontal
position be the right edge of the inline box.</dd>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">center</code></dt>
<dd>Let the <var title="">anchor point</var>'s horizontal
position be half way between the left and right edges of the
inline box.</dd>
</dl>
<p>Vertical position:</p>
<dl>
<dt> If <code
title="dom-context-2d-textBaseline">textBaseline</code> is <code
title="dom-context-2d-textBaseline-top">top</code></dt>
<dd>Let the <var title="">anchor point</var>'s vertical position
be the top of the em box of the first available font of the
inline box.</dd>
<dt> If <code
title="dom-context-2d-textBaseline">textBaseline</code> is <code
title="dom-context-2d-textBaseline-hanging">hanging</code></dt>
<dd>Let the <var title="">anchor point</var>'s vertical position
be the hanging baseline of the first available font of the inline
box.</dd>
<dt> If <code
title="dom-context-2d-textBaseline">textBaseline</code> is <code
title="dom-context-2d-textBaseline-middle">middle</code></dt>
<dd>Let the <var title="">anchor point</var>'s vertical position
be half way between the bottom and the top of the em box of the
first available font of the inline box.</dd>
<dt> If <code
title="dom-context-2d-textBaseline">textBaseline</code> is <code
title="dom-context-2d-textBaseline-alphabetic">alphabetic</code></dt>
<dd>Let the <var title="">anchor point</var>'s vertical position
be the alphabetic baseline of the first available font of the inline
box.</dd>
<dt> If <code
title="dom-context-2d-textBaseline">textBaseline</code> is <code
title="dom-context-2d-textBaseline-ideographic">ideographic</code></dt>
<dd>Let the <var title="">anchor point</var>'s vertical position
be the ideographic baseline of the first available font of the inline
box.</dd>
<dt> If <code
title="dom-context-2d-textBaseline">textBaseline</code> is <code
title="dom-context-2d-textBaseline-bottom">bottom</code></dt>
<dd>Let the <var title="">anchor point</var>'s vertical position
be the bottom of the em box of the first available font of the
inline box.</dd>
</dl>
</li>
<li>
<p>Paint the hypothetical inline box as the shape given by the
text's glyphs, as transformed by the <span
title="dom-context-2d-transformation">current transformation
matrix</span>, and anchored and sized so that before applying the
<span title="dom-context-2d-transformation">current transformation
matrix</span>, the <var title="">anchor point</var> is at (<var
title="">x</var>, <var title="">y</var>) and each CSS pixel is
mapped to one coordinate space unit.</p>
<p>For <code title="dom-context-2d-fillText">fillText()</code>
<code title="dom-context-2d-fillStyle">fillStyle</code> must be
applied to the glyphs and <code
title="dom-context-2d-strokeStyle">strokeStyle</code> must be
ignored. For <code
title="dom-context-2d-strokeText">strokeText()</code> the reverse
holds and <code
title="dom-context-2d-strokeStyle">strokeStyle</code> must be
applied to the glyph outlines and <code
title="dom-context-2d-fillStyle">fillStyle</code> must be
ignored.</p>
<p>Text is painted without affecting the current path, and is
subject to <span title="shadows">shadow effects</span>, <span
title="dom-context-2d-globalAlpha">global alpha</span>, the <span
title="clipping region">clipping region</span>, and <span
title="dom-context-2d-globalCompositeOperation">global composition
operators</span>.</p>
</li>
</ol>
<!--v4DVT - this is commented out until CSS can get its act together
enough to actual specify vertical text rendering (how long have we
been waiting now?)
WHEN EDITING THIS, FIX THE PARTS MARKED "XXX" BELOW
<p>The <dfn
title="dom-context-2d-fillVerticalText"><code>fillVerticalText()</code></dfn>
and <dfn
title="dom-context-2d-strokeVerticalText"><code>strokeVerticalText()</code></dfn>
methods take three or four arguments, <var title="">text</var>, <var
title="">x</var>, <var title="">y</var>, and optionally <var
title="">maxHeight</var>, and render the given <var
title="">text</var> as vertical text at the given (<var
title="">x</var>, <var title="">y</var>) coordinates ensuring that
the text isn't taller than <var title="">maxHeight</var> if
specified, using the current <code
title="dom-context-2d-font">font</code> and <code
title="dom-context-2d-textAlign">textAlign</code>
values. Specifically, when the methods are called, the user agent
must run the following steps:</p>
<ol>
<li><p>Let <var title="">font</var> be the current font of the
context, as given by the <code
title="dom-context-2d-font">font</code> attribute.</p></li>
<li><p>Replace all the <span title="space character">space
characters</span> in <var title="">text</var> with U+0020 SPACE
characters.</p></li>
<li><p>Form a <em class="XXX">whatever CSS ends up calling
vertical line boxes and inline boxes</em> containing the text <var
title="">text</var>, with all the properties at their initial
values except the 'font' property of the inline box set to <var
title="">font</var> and the 'direction' property of the inline
box set to <span>the directionality</span> of the <code>canvas</code>
element.</p></li>
<!- - if you insert a step here, make sure to adjust the next step's
final words - ->
<li><p>If the <var title="">maxHeight</var> argument was specified
and the hypothetical height of the <em class="XXX">box</em>
in the hypothetical line box is greater than <var
title="">maxHeight</var> CSS pixels, then change <var
title="">font</var> to have a more condensed font (if one is
available or if a reasonably readable one can be synthesized by
applying an appropriate scale factor to the font) or a smaller
font, and return to the previous step.</p></li>
<li>
<p>Let the <var title="">anchor point</var> be a point on the <em
class="XXX">inline box</var>, determined by the <code
title="dom-context-2d-textAlign">textAlign</code>, as follows:</p>
<p>Vertical position:</p>
<dl>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">start</code></dt>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">left</code> and <span>the directionality</span> of the
<code>canvas</code> element is 'ltr'</dt>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">right</code> and <span>the directionality</span> of the
<code>canvas</code> element is 'rtl'</dt>
<dd>Let the <var title="">anchor point</var>'s vertical
position be the top edge of the <em class="XXX">inline
box</em>.</dd>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">end</code></dt>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">right</code> and <span>the directionality</span> of the
<code>canvas</code> element is 'ltr'</dt>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">left</code> and <span>the directionality</span> of the
<code>canvas</code> element is 'rtl'</dt>
<dd>Let the <var title="">anchor point</var>'s vertical
position be the bottom edge of the <em class="XXX">inline
box</em>.</dd>
<dt> If <code
title="dom-context-2d-textAlign">textAlign</code> is <code
title="">center</code></dt>
<dd>Let the <var title="">anchor point</var>'s vertical position
be half way between the top and bottom edges of the <em
class="XXX">inline box</em>.</dd>
</dl>
<p>Let the horizontal position be half way between the left and
right edges of the em box of the first available font of the <em
class="XXX">inline box</em>.</p>
</li>
<li>
<p>Paint the hypothetical inline box as the shape given by the
text's glyphs, as transformed by the <span
title="dom-context-2d-transformation">current transformation
matrix</span>, and anchored and sized so that before applying the
<span title="dom-context-2d-transformation">current transformation
matrix</span>, the <var title="">anchor point</var> is at (<var
title="">x</var>, <var title="">y</var>) and each CSS pixel is
mapped to one coordinate space unit.</p>
<p>For <code
title="dom-context-2d-fillVerticalText">fillVerticalText()</code>
<code title="dom-context-2d-fillStyle">fillStyle</code> must be
applied and <code
title="dom-context-2d-strokeStyle">strokeStyle</code> must be
ignored. For <code
title="dom-context-2d-strokeVerticalText">strokeVerticalText()</code>
the reverse holds and <code
title="dom-context-2d-strokeStyle">strokeStyle</code> must be
applied and <code
title="dom-context-2d-fillStyle">fillStyle</code> must be
ignored.</p>
<p>Text is painted without affecting the current path, and is
subject to <span title="shadows">shadow effects</span>, <span
title="dom-context-2d-globalAlpha">global alpha</span>, the <span
title="clipping region">clipping region</span>, and <span
title="dom-context-2d-globalCompositeOperation">global composition
operators</span>.</p>
</li>
</ol>
v4DVT (also check for '- -' bits in the part above) -->
<p>The <dfn
title="dom-context-2d-measureText"><code>measureText()</code></dfn>
method takes one argument, <var title="">text</var>. When the method
is invoked, the user agent must replace all the <span title="space
character">space characters</span> in <var title="">text</var> with
U+0020 SPACE characters, and then must form a hypothetical
infinitely wide CSS line box containing a single inline box
containing the text <var title="">text</var>, with all the
properties at their initial values except the 'font' property of the
inline element set to the current font of the context, as given by
the <code title="dom-context-2d-font">font</code> attribute, and
must then return a new <code>TextMetrics</code> object with its
<code title="dom-textmetrics-width">width</code> attribute set to
the width of that inline box, in CSS pixels. <a
href="#refsCSS">[CSS]</a></p>
<p>The <code>TextMetrics</code> interface is used for the objects
returned from <code
title="dom-context-2d-measureText">measureText()</code>. It has one
attribute, <dfn
title="dom-textmetrics-width"><code>width</code></dfn>, which is set
by the <code title="dom-context-2d-measureText">measureText()</code>
method.</p>
<p class="note">Glyphs rendered using <code
title="dom-context-2d-fillText">fillText()</code> and <code
title="dom-context-2d-strokeText">strokeText()</code> can spill out
of the box given by the font size (the em square size) and the width
returned by <code
title="dom-context-2d-measureText">measureText()</code> (the text
width). This version of the specification does not provide a way to
obtain the bounding box dimensions of the text. If the text is to be
rendered and removed, care needs to be taken to replace the entire
area of the canvas that the clipping region covers, not just the box
given by the em square height and measured text width.</p>
<!-- v4: Drawing text along a given path -->
<!-- v4: Adding text to a path -->
<!-- see also: http://www.w3.org/TR/SVG11/text.html#TextpathLayoutRules -->
<!-- see also: http://developer.mozilla.org/en/docs/Drawing_text_using_a_canvas -->
</div>
<p class="note">A future version of the 2D context API may provide a
way to render fragments of documents, rendered using CSS, straight
to the canvas. This would be provided in preference to a dedicated
way of doing multiline layout.</p>
<h6>Images</h6>
<p>To draw images onto the canvas, the <dfn
title="dom-context-2d-drawImage"><code>drawImage</code></dfn> method
can be used.</p>
<p>This method can be invoked with three different sets of arguments:</p>
<ul class="brief">
<li><code title="">drawImage(<var title="">image</var>, <var title="">dx</var>, <var title="">dy</var>)</code>
<li><code title="">drawImage(<var title="">image</var>, <var title="">dx</var>, <var title="">dy</var>, <var title="">dw</var>, <var title="">dh</var>)</code>
<li><code title="">drawImage(<var title="">image</var>, <var title="">sx</var>, <var title="">sy</var>, <var title="">sw</var>, <var title="">sh</var>, <var title="">dx</var>, <var title="">dy</var>, <var title="">dw</var>, <var title="">dh</var>)</code>
</ul>
<!-- v3: drawImage() of an ImageData object might make sense (when resizing as well as filtering) - ack Charles Pritchard -->
<p>Each of those three can take either an
<code>HTMLImageElement</code>, an <code>HTMLCanvasElement</code>, or
an <code>HTMLVideoElement</code> for the <var title="">image</var>
argument.</p>
<dl class="domintro">
<dt><var title="">context</var> . <code title="">drawImage</code>(<var title="">image</var>, <var title="">dx</var>, <var title="">dy</var>)</dt>
<dt><var title="">context</var> . <code title="">drawImage</code>(<var title="">image</var>, <var title="">dx</var>, <var title="">dy</var>, <var title="">dw</var>, <var title="">dh</var>)</dt>
<dt><var title="">context</var> . <code title="">drawImage</code>(<var title="">image</var>, <var title="">sx</var>, <var title="">sy</var>, <var title="">sw</var>, <var title="">sh</var>, <var title="">dx</var>, <var title="">dy</var>, <var title="">dw</var>, <var title="">dh</var>)</dt>
<dd>
<p>Draws the given image onto the canvas. The arguments are
interpreted as follows:</p>
<p><img src="images/drawImage.png" alt="The sx and sy parameters give the x and y coordinates of the source rectangle; the sw and sh arguments give the width and height of the source rectangle; the dx and dy give the x and y coordinates of the destination rectangle; and the dw and dh arguments give the width and height of the destination rectangle."></p>
<p>If the first argument isn't an <code>img</code>,
<code>canvas</code>, or <code>video</code> element, throws a
<code>TYPE_MISMATCH_ERR</code> exception. If the image has no
image data, throws an <code>INVALID_STATE_ERR</code> exception. If
the second argument isn't one of the allowed values, throws a
<code>SYNTAX_ERR</code> exception. If the image isn't yet fully
decoded, then nothing is drawn.</p>
</dd>
</dl>
<div class="impl">
<p>If not specified, the <var title="">dw</var> and <var
title="">dh</var> arguments must default to the values of <var
title="">sw</var> and <var title="">sh</var>, interpreted such that
one CSS pixel in the image is treated as one unit in the canvas
coordinate space. If the <var title="">sx</var>, <var
title="">sy</var>, <var title="">sw</var>, and <var
title="">sh</var> arguments are omitted, they must default to 0, 0,
the image's intrinsic width in image pixels, and the image's
intrinsic height in image pixels, respectively.</p>
<p>The <var title="">image</var> argument is an instance of either
<code>HTMLImageElement</code>, <code>HTMLCanvasElement</code>, or
<code>HTMLVideoElement</code>. If the <var title="">image</var> is
of the wrong type or null, the implementation must raise a
<code>TYPE_MISMATCH_ERR</code> exception.</p>
<!-- createPattern() has an equivalent paragraph -->
<p>If the <var title="">image</var> argument is an
<code>HTMLImageElement</code> object whose <code
title="dom-img-complete">complete</code> attribute is false, or
if the <var title="">image</var> argument is an
<code>HTMLVideoElement</code> object whose <code
title="dom-media-readyState">readyState</code> attribute is either
<code title="dom-media-HAVE_NOTHING">HAVE_NOTHING</code> or <code
title="dom-media-HAVE_METADATA">HAVE_METADATA</code>, then the
implementation must return without drawing anything.</p>
<!-- createPattern() has an equivalent paragraph -->
<p>If the <var title="">image</var> argument is an
<code>HTMLCanvasElement</code> object with either a horizontal
dimension or a vertical dimension equal to zero, then the
implementation must raise an <code>INVALID_STATE_ERR</code>
exception.</p>
<!-- createPattern() has an equivalent paragraph -->
<p>The source rectangle is the rectangle whose corners are the four
points (<var title="">sx</var>, <var title="">sy</var>), (<span title=""><var
title="">sx</var>+<var title="">sw</var></span>, <var
title="">sy</var>), (<span title=""><var title="">sx</var>+<var
title="">sw</var></span>, <span title=""><var title="">sy</var>+<var
title="">sh</var></span>), (<var title="">sx</var>, <span title=""><var
title="">sy</var>+<var title="">sh</var></span>).</p>
<p>If the source rectangle is not entirely within the source image,
or if one of the <var title="">sw</var> or <var title="">sh</var>
arguments is zero, the implementation must raise an
<code>INDEX_SIZE_ERR</code> exception.</p>
<p>The destination rectangle is the rectangle whose corners are the
four points (<var title="">dx</var>, <var title="">dy</var>),
(<span title=""><var title="">dx</var>+<var title="">dw</var></span>, <var
title="">dy</var>), (<span title=""><var title="">dx</var>+<var
title="">dw</var></span>, <span title=""><var title="">dy</var>+<var
title="">dh</var></span>), (<var title="">dx</var>, <span title=""><var
title="">dy</var>+<var title="">dh</var></span>).</p>
<p>When <code title="dom-context-2d-drawImage">drawImage()</code> is
invoked, the region of the image specified by the source rectangle
must be painted on the region of the canvas specified by the
destination rectangle, after applying the <span
title="dom-context-2d-transformation">current transformation
matrix</span> to the points of the destination rectangle.</p>
<p>The original image data of the source image must be used, not the
image as it is rendered (e.g. <code
title="attr-dim-width">width</code> and <code
title="attr-dim-height">height</code> attributes on the source
element have no effect). The image data must be processed in the
original direction, even if the dimensions given are negative. <!--
remove that last sentence if it causes confusion. Someone once
suggested that 5,5,-2,-2 was different than 3,3,2,2; this is trying
to clarify that this is no the case. --></p>
<p class="note">This specification does not define the algorithm to
use when scaling the image, if necessary.</p>
<p class="note">When a canvas is drawn onto itself, the drawing
model requires the source to be copied before the image is drawn
back onto the canvas, so it is possible to copy parts of a canvas
onto overlapping parts of itself.</p>
<p>When the <code
title="dom-context-2d-drawImage">drawImage()</code> method
is passed an animated image as its <var title="">image</var>
argument, the user agent must use the poster frame of the animation,
or, if there is no poster frame, the first frame of the
animation.</p>
<!-- createPattern() has an equivalent paragraph -->
<p>When the <var title="">image</var> argument is an
<code>HTMLVideoElement</code>, then the frame at the <span>current
playback position</span> must be used as the source image, and the
source image's dimensions must be the <span
title="concept-video-intrinsic-width">intrinsic width</span> and
<span title="concept-video-intrinsic-height">intrinsic height</span>
of the <span>media resource</span> (i.e. after any aspect-ratio
correction has been applied).</p>
<!-- createPattern() has an equivalent paragraph -->
<p>Images are painted without affecting the current path, and are
subject to <span title="shadows">shadow effects</span>, <span
title="dom-context-2d-globalAlpha">global alpha</span>, the <span
title="clipping region">clipping region</span>, and <span
title="dom-context-2d-globalCompositeOperation">global composition
operators</span>.</p>
</div>
<h6><dfn>Pixel manipulation</dfn></h6>
<dl class="domintro">
<dt><var title="">imagedata</var> = <var title="">context</var> . <code title="dom-context-2d-createImageData">createImageData</code>(<var title="">sw</var>, <var title="">sh</var>)</dt>
<dd>
<p>Returns an <code>ImageData</code> object with the given
dimensions in CSS pixels (which might map to a different number of
actual device pixels exposed by the object itself). All the pixels
in the returned object are transparent black.</p>
</dd>
<dt><var title="">imagedata</var> = <var title="">context</var> . <code title="dom-context-2d-createImageData">createImageData</code>(<var title="">imagedata</var>)</dt>
<dd>
<p>Returns an <code>ImageData</code> object with the same
dimensions as the argument. All the pixels in the returned object
are transparent black.</p>
<p>Throws a <code>NOT_SUPPORTED_ERR</code> exception if the
argument is null.</p>
</dd>
<dt><var title="">imagedata</var> = <var title="">context</var> . <code title="dom-context-2d-getImageData">getImageData</code>(<var title="">sx</var>, <var title="">sy</var>, <var title="">sw</var>, <var title="">sh</var>)</dt>
<dd>
<p>Returns an <code>ImageData</code> object containing the image
data for the given rectangle of the canvas.</p>
<p>Throws a <code>NOT_SUPPORTED_ERR</code> exception if any of the
arguments are not finite. Throws an <code>INDEX_SIZE_ERR</code>
exception if the either of the width or height arguments are
zero.</p>
</dd>
<dt><var title="">imagedata</var> . <code title="dom-imagedata-width">width</code></dt>
<dt><var title="">imagedata</var> . <code title="dom-imagedata-height">height</code></dt>
<dd>
<p>Returns the actual dimensions of the data in the <code>ImageData</code> object, in device pixels.</p>
</dd>
<dt><var title="">imagedata</var> . <code title="dom-imagedata-data">data</code></dt>
<dd>
<p>Returns the one-dimensional array containing the data.</p>
</dd>
<dt><var title="">context</var> . <code title="dom-context-2d-putImageData">putImageData</code>(<var title="">imagedata</var>, <var title="">dx</var>, <var title="">dy</var> [, <var title="">dirtyX</var>, <var title="">dirtyY</var>, <var title="">dirtyWidth</var>, <var title="">dirtyHeight</var> ])</dt>
<dd>
<p>Paints the data from the given <code>ImageData</code> object
onto the canvas. If a dirty rectangle is provided, only the pixels
from that rectangle are painted.</p>
<p>The <code title="dom-context-2d-globalAlpha">globalAlpha</code>
and <code
title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</code>
attributes, as well as the shadow attributes, are ignored for the
purposes of this method call; pixels in the canvas are replaced
wholesale, with no composition, alpha blending, no shadows,
etc.</p>
<p>If the first argument isn't an <code>ImageData</code> object,
throws a <code>TYPE_MISMATCH_ERR</code> exception. Throws a
<code>NOT_SUPPORTED_ERR</code> exception if any of the other
arguments are not finite.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-context-2d-createImageData"><code>createImageData()</code></dfn>
method is used to instantiate new blank <code>ImageData</code>
objects. When the method is invoked with two arguments <var
title="">sw</var> and <var title="">sh</var>, it must return an
<code>ImageData</code> object representing a rectangle with a width
in CSS pixels equal to the absolute magnitude of <var
title="">sw</var> and a height in CSS pixels equal to the absolute
magnitude of <var title="">sh</var>. When invoked with a single <var
title="">imagedata</var> argument, it must return an
<code>ImageData</code> object representing a rectangle with the same
dimensions as the <code>ImageData</code> object passed as the
argument. The <code>ImageData</code> object return must be filled
with transparent black.</p>
<p>The <dfn
title="dom-context-2d-getImageData"><code>getImageData(<var
title="">sx</var>, <var title="">sy</var>, <var title="">sw</var>,
<var title="">sh</var>)</code></dfn> method must return an
<code>ImageData</code> object representing the underlying pixel data
for the area of the canvas denoted by the rectangle whose corners are
the four points (<var title="">sx</var>, <var title="">sy</var>),
(<span title=""><var title="">sx</var>+<var title="">sw</var></span>, <var
title="">sy</var>), (<span title=""><var title="">sx</var>+<var
title="">sw</var></span>, <span title=""><var title="">sy</var>+<var
title="">sh</var></span>), (<var title="">sx</var>, <span title=""><var
title="">sy</var>+<var title="">sh</var></span>), in canvas
coordinate space units. Pixels outside the canvas must be returned
as transparent black. Pixels must be returned as non-premultiplied
alpha values.</p>
<p>If any of the arguments to <code
title="dom-context-2d-createImageData">createImageData()</code> or
<code title="dom-context-2d-getImageData">getImageData()</code> are
infinite or NaN, or if the <code
title="dom-context-2d-createImageData">createImageData()</code>
method is invoked with only one argument but that argument is null,
the method must instead raise a <code>NOT_SUPPORTED_ERR</code>
exception. If either the <var title="">sw</var> or <var
title="">sh</var> arguments are zero, the method must instead raise
an <code>INDEX_SIZE_ERR</code> exception.</p>
<p><code>ImageData</code> objects must be initialized so that their
<dfn title="dom-imagedata-width"><code>width</code></dfn> attribute
is set to <var title="">w</var>, the number of physical device
pixels per row in the image data, their <dfn
title="dom-imagedata-height"><code>height</code></dfn> attribute is
set to <var title="">h</var>, the number of rows in the image data,
and their <dfn title="dom-imagedata-data"><code>data</code></dfn>
attribute is initialized to a <code>CanvasPixelArray</code> object
holding the image data. At least one pixel's worth of image data
must be returned.</p>
<p>The <code>CanvasPixelArray</code> object provides ordered,
indexed access to the color components of each pixel of the image
data. The data must be represented in left-to-right order, row by
row top to bottom, starting with the top left, with each pixel's
red, green, blue, and alpha components being given in that order for
each pixel. Each component of each device pixel represented in this
array must be in the range 0..255, representing the 8 bit value for
that component. The components must be assigned consecutive indices
starting with 0 for the top left pixel's red component.</p>
<p>The <code>CanvasPixelArray</code> object thus represents <var
title="">h</var>×<var title="">w</var>×4 integers. The
<dfn title="dom-canvaspixelarray-length"><code>length</code></dfn>
attribute of a <code>CanvasPixelArray</code> object must return this
number.</p>
<p>The object's <span>indices of the supported indexed
properties</span> are the numbers in the range 0 .. <span title=""><var
title="">h</var>×<var title="">w</var>×4-1</span>.</p>
<p>When a <code>CanvasPixelArray</code> object is <dfn
title="dom-CanvasPixelArray-get">indexed to retrieve an indexed
property</dfn> <var title="">index</var>, the value returned must be
the value of the <var title="">index</var>th component in the
array.</p>
<p>When a <code>CanvasPixelArray</code> object is <dfn
title="dom-CanvasPixelArray-set">indexed to modify an indexed
property</dfn> <var title="">index</var> with value <var
title="">value</var>, the value of the <var title="">index</var>th
component in the array must be set to <var title="">value</var>. JS
<code>undefined</code> values must be converted to zero. Other
values must first be converted to numbers using JavaScript's
ToNumber algorithm, and if the result is a NaN value, then the value
must be converted to zero. If the result is less than 0, it must be
clamped to zero. If the result is more than 255, it must be clamped
to 255. If the number is not an integer, it should be rounded to the
nearest integer using the IEEE 754 <i>convertToIntegerTiesToEven</i>
rounding mode. <a href="#refsECMA262">[ECMA262]</a> <a
href="#refsIEEE754">[IEEE754]</a></p>
<p class="note">The width and height (<var title="">w</var> and <var
title="">h</var>) might be different from the <var title="">sw</var>
and <var title="">sh</var> arguments to the above methods, e.g. if
the canvas is backed by a high-resolution bitmap, or if the <var
title="">sw</var> and <var title="">sh</var> arguments are
negative.</p>
<p>The <dfn
title="dom-context-2d-putImageData"><code>putImageData(<var
title="">imagedata</var>, <var title="">dx</var>, <var
title="">dy</var>, <var title="">dirtyX</var>, <var
title="">dirtyY</var>, <var title="">dirtyWidth</var>, <var
title="">dirtyHeight</var>)</code></dfn> method writes data from
<code>ImageData</code> structures back to the canvas.</p>
<p>If any of the arguments to the method are infinite or NaN, the
method must raise a <code>NOT_SUPPORTED_ERR</code> exception.</p>
<p>If the first argument to the method is null or not an
<code>ImageData</code> object then the <code
title="dom-context-2d-putImageData">putImageData()</code> method
must raise a <code>TYPE_MISMATCH_ERR</code> exception.</p>
<p>When the last four arguments are omitted, they must be assumed to
have the values 0, 0, the <code
title="dom-imagedata-width">width</code> member of the <var
title="">imagedata</var> structure, and the <code
title="dom-imagedata-height">height</code> member of the <var
title="">imagedata</var> structure, respectively.</p>
<p>When invoked with arguments that do not, per the last few
paragraphs, cause an exception to be raised, the <code
title="dom-context-2d-putImageData">putImageData()</code> method
must act as follows:</p>
<ol>
<li>
<p>Let <var title="">dx<sub>device</sub></var> be the x-coordinate
of the device pixel in the underlying pixel data of the canvas
corresponding to the <var title="">dx</var> coordinate in the
canvas coordinate space.</p>
<p>Let <var title="">dy<sub>device</sub></var> be the y-coordinate
of the device pixel in the underlying pixel data of the canvas
corresponding to the <var title="">dy</var> coordinate in the
canvas coordinate space.</p>
</li>
<li>
<p>If <var title="">dirtyWidth</var> is negative, let <var
title="">dirtyX</var> be <span title=""><var title="">dirtyX</var>+<var
title="">dirtyWidth</var></span>, and let <var
title="">dirtyWidth</var> be equal to the absolute magnitude of
<var title="">dirtyWidth</var>.</p>
<p>If <var title="">dirtyHeight</var> is negative, let <var
title="">dirtyY</var> be <span title=""><var title="">dirtyY</var>+<var
title="">dirtyHeight</var></span>, and let <var
title="">dirtyHeight</var> be equal to the absolute magnitude of
<var title="">dirtyHeight</var>.</p>
</li>
<li>
<p>If <var title="">dirtyX</var> is negative, let <var
title="">dirtyWidth</var> be <span title=""><var
title="">dirtyWidth</var>+<var title="">dirtyX</var></span>, and
let <var title="">dirtyX</var> be zero.</p>
<p>If <var title="">dirtyY</var> is negative, let <var
title="">dirtyHeight</var> be <span title=""><var
title="">dirtyHeight</var>+<var title="">dirtyY</var></span>, and
let <var title="">dirtyY</var> be zero.</p>
</li>
<li>
<p>If <span title=""><var title="">dirtyX</var>+<var
title="">dirtyWidth</var></span> is greater than the <code
title="dom-imagedata-width">width</code> attribute of the <var
title="">imagedata</var> argument, let <var
title="">dirtyWidth</var> be the value of that <code
title="dom-imagedata-width">width</code> attribute, minus the
value of <var title="">dirtyX</var>.</p>
<p>If <span title=""><var title="">dirtyY</var>+<var
title="">dirtyHeight</var></span> is greater than the <code
title="dom-imagedata-height">height</code> attribute of the <var
title="">imagedata</var> argument, let <var
title="">dirtyHeight</var> be the value of that <code
title="dom-imagedata-height">height</code> attribute, minus the
value of <var title="">dirtyY</var>.</p>
</li>
<li>
<p>If, after those changes, either <var title="">dirtyWidth</var>
or <var title="">dirtyHeight</var> is negative or zero, stop these
steps without affecting the canvas.</p>
</li>
<li><p>Otherwise, for all integer values of <var title="">x</var>
and <var title="">y</var> where <span title=""><var
title="">dirtyX</var> ≤ <var
title="">x</var> < <span title=""><var
title="">dirtyX</var>+<var title="">dirtyWidth</var></span></span>
and <span title=""><var title="">dirtyY</var> ≤ <var
title="">y</var> < <span title=""><var
title="">dirtyY</var>+<var
title="">dirtyHeight</var></span></span>, copy the four channels of
the pixel with coordinate (<var title="">x</var>, <var
title="">y</var>) in the <var title="">imagedata</var> data
structure to the pixel with coordinate (<span title=""><var
title="">dx<sub>device</sub></var>+<var title="">x</var></span>,
<span title=""><var title="">dy<sub>device</sub></var>+<var
title="">y</var></span>) in the underlying pixel data of the
canvas.</p></li>
</ol>
<p>The handling of pixel rounding when the specified coordinates do
not exactly map to the device coordinate space is not defined by
this specification, except that the following must result in no
visible changes to the rendering:</p>
<pre>context.putImageData(context.getImageData(x, y, w, h), p, q);</pre>
<p>...for any value of <var title="">x</var>, <var title="">y</var>,
<var title="">w</var>, and <var title="">h</var> and where <var
title="">p</var> is the smaller of <var title="">x</var> and the sum
of <var title="">x</var> and <var title="">w</var>, and <var
title="">q</var> is the smaller of <var title="">y</var> and the sum
of <var title="">y</var> and <var title="">h</var>; and except that
the following two calls:</p>
<pre>context.createImageData(w, h);
context.getImageData(0, 0, w, h);</pre>
<p>...must return <code>ImageData</code> objects with the same
dimensions, for any value of <var title="">w</var> and <var
title="">h</var>. In other words, while user agents may round the
arguments of these methods so that they map to device pixel
boundaries, any rounding performed must be performed consistently
for all of the <code
title="dom-context-2d-getImageData">createImageData()</code>, <code
title="dom-context-2d-getImageData">getImageData()</code> and <code
title="dom-context-2d-putImageData">putImageData()</code>
operations.</p>
<p class="note">Due to the lossy nature of converting to and from
premultiplied alpha color values, pixels that have just been set
using <code
title="dom-context-2d-putImageData">putImageData()</code> might be
returned to an equivalent <code
title="dom-context-2d-getImageData">getImageData()</code> as
different values.</p>
<p>The current path, <span
title="dom-context-2d-transformation">transformation matrix</span>,
<span title="shadows">shadow attributes</span>, <span
title="dom-context-2d-globalAlpha">global alpha</span>, the <span
title="clipping region">clipping region</span>, and <span
title="dom-context-2d-globalCompositeOperation">global composition
operator</span> must not affect the <code
title="dom-context-2d-getImageData">getImageData()</code> and <code
title="dom-context-2d-putImageData">putImageData()</code>
methods.</p>
</div>
<div class="example">
<p>The data returned by <code
title="dom-context-2d-getImageData">getImageData()</code> is at the
resolution of the canvas backing store, which is likely to not be
one device pixel to each CSS pixel if the display used is a high
resolution display.</p>
<p>In the following example, the script generates an
<code>ImageData</code> object so that it can draw onto it.</p>
<pre>// canvas is a reference to a <canvas> element
var context = canvas.getContext('2d');
// create a blank slate
var data = context.createImageData(canvas.width, canvas.height);
// create some plasma
FillPlasma(data, 'green'); // green plasma
// add a cloud to the plasma
AddCloud(data, data.width/2, data.height/2); // put a cloud in the middle
// paint the plasma+cloud on the canvas
context.putImageData(data, 0, 0);
// support methods
function FillPlasma(data, color) { ... }
function AddCloud(data, x, y) { ... }</pre>
</div>
<div class="example">
<p>Here is an example of using <code
title="dom-context-2d-getImageData">getImageData()</code> and <code
title="dom-context-2d-putImageData">putImageData()</code> to
implement an edge detection filter.</p>
<pre><!DOCTYPE HTML>
<html>
<head>
<title>Edge detection demo</title>
<script>
var image = new Image();
function init() {
image.onload = demo;
image.src = "image.jpeg";
}
function demo() {
var canvas = document.getElementsByTagName('canvas')[0];
var context = canvas.getContext('2d');
// draw the image onto the canvas
context.drawImage(image, 0, 0);
// get the image data to manipulate
var input = context.getImageData(0, 0, canvas.width, canvas.height);
// get an empty slate to put the data into
var output = context.createImageData(canvas.width, canvas.height);
// alias some variables for convenience
// notice that we are using input.width and input.height here
// as they might not be the same as canvas.width and canvas.height
// (in particular, they might be different on high-res displays)
var w = input.width, h = input.height;
var inputData = input.data;
var outputData = output.data;
// edge detection
for (var y = 1; y < h-1; y += 1) {
for (var x = 1; x < w-1; x += 1) {
for (var c = 0; c < 3; c += 1) {
var i = (y*w + x)*4 + c;
outputData[i] = 127 + -inputData[i - w*4 - 4] - inputData[i - w*4] - inputData[i - w*4 + 4] +
-inputData[i - 4] + 8*inputData[i] - inputData[i + 4] +
-inputData[i + w*4 - 4] - inputData[i + w*4] - inputData[i + w*4 + 4];
}
outputData[(y*w + x)*4 + 3] = 255; // alpha
}
}
// put the image data back after manipulation
context.putImageData(output, 0, 0);
}
</script>
</head>
<body onload="init()">
<canvas></canvas>
</body>
</html></pre>
</div>
<div class="impl">
<h6>Drawing model</h6>
<p>When a shape or image is painted, user agents must follow these
steps, in the order given (or act as if they do):</p>
<ol>
<li><p>Render the shape or image onto an infinite transparent black
bitmap, creating image <var title="">A</var>, as described in the
previous sections. For shapes, the current fill, stroke, and line
styles must be honored, and the stroke must itself also be
subjected to the current transformation matrix.</p></li>
<li><p><span>When shadows are drawn</span>, render the shadow from
image <var title="">A</var>, using the current shadow styles,
creating image <var title="">B</var>.</p></li>
<li><p><span>When shadows are drawn</span>, multiply the alpha
component of every pixel in <var title="">B</var> by <code
title="dom-context-2d-globalAlpha">globalAlpha</code>.</p></li>
<li><p><span>When shadows are drawn</span>, composite <var
title="">B</var> within the clipping region over the current canvas
bitmap using the current composition operator.</p></li>
<li><p>Multiply the alpha component of every pixel in <var
title="">A</var> by <code
title="dom-context-2d-globalAlpha">globalAlpha</code>.</p></li>
<li><p>Composite <var title="">A</var> within the clipping region
over the current canvas bitmap using the current composition
operator.</p></li>
</ol>
</div>
<h6>Examples</h6>
<p><i>This section is non-normative.</i></p>
<p>Here is an example of a script that uses canvas to draw pretty
glowing lines.</p>
<pre><canvas width="800" height="450"></canvas>
<script>
var context = document.getElementsByTagName('canvas')[0].getContext('2d');
var lastX = context.canvas.width * Math.random();
var lastY = context.canvas.height * Math.random();
var hue = 0;
function line() {
context.save();
context.translate(context.canvas.width/2, context.canvas.height/2);
context.scale(0.9, 0.9);
context.translate(-context.canvas.width/2, -context.canvas.height/2);
context.beginPath();
context.lineWidth = 5 + Math.random() * 10;
context.moveTo(lastX, lastY);
lastX = context.canvas.width * Math.random();
lastY = context.canvas.height * Math.random();
context.bezierCurveTo(context.canvas.width * Math.random(),
context.canvas.height * Math.random(),
context.canvas.width * Math.random(),
context.canvas.height * Math.random(),
lastX, lastY);
hue = hue + 10 * Math.random();
context.strokeStyle = 'hsl(' + hue + ', 50%, 50%)';
context.shadowColor = 'white';
context.shadowBlur = 10;
context.stroke();
context.restore();
}
setInterval(line, 50);
function blank() {
context.fillStyle = 'rgba(0,0,0,0.1)';
context.fillRect(0, 0, context.canvas.width, context.canvas.height);
}
setInterval(blank, 40);
</script></pre>
<div class="impl">
<h5>Color spaces and color correction</h5>
<p>The <code>canvas</code> APIs must perform color correction at
only two points: when rendering images with their own gamma
correction and color space information onto the canvas, to convert
the image to the color space used by the canvas (e.g. using the
<code title="dom-context-2d-drawImage">drawImage()</code> method
with an <code>HTMLImageElement</code> object), and when rendering
the actual canvas bitmap to the output device.</p>
<p class="note">Thus, in the 2D context, colors used to draw shapes
onto the canvas will exactly match colors obtained through the <code
title="dom-context-2d-getImageData">getImageData()</code>
method.</p>
<p>The <code title="dom-canvas-toDataURL">toDataURL()</code> method
must not include color space information in the resource
returned. Where the output format allows it, the color of pixels in
resources created by <code
title="dom-canvas-toDataURL">toDataURL()</code> must match those
returned by the <code
title="dom-context-2d-getImageData">getImageData()</code>
method.</p>
<p>In user agents that support CSS, the color space used by a
<code>canvas</code> element must match the color space used for
processing any colors for that element in CSS.</p>
<p>The gamma correction and color space information of images must
be handled in such a way that an image rendered directly using an
<code>img</code> element would use the same colors as one painted on
a <code>canvas</code> element that is then itself
rendered. Furthermore, the rendering of images that have no color
correction information (such as those returned by the <code
title="dom-canvas-toDataURL">toDataURL()</code> method) must be
rendered with no color correction.</p>
<p class="note">Thus, in the 2D context, calling the <code
title="dom-context-2d-drawImage">drawImage()</code> method to render
the output of the <code
title="dom-canvas-toDataURL">toDataURL()</code> method to the
canvas, given the appropriate dimensions, has no visible effect.</p>
</div>
<div class="impl">
<h5>Security with <code>canvas</code> elements</h5>
<p><strong>Information leakage</strong> can occur if scripts from
one <span>origin</span> can access information (e.g. read pixels)
from images from another origin (one that isn't the <span
title="same origin">same</span>).</p>
<p>To mitigate this, <code>canvas</code> elements are defined to
have a flag indicating whether they are <i>origin-clean</i>. All
<code>canvas</code> elements must start with their
<i>origin-clean</i> set to true. The flag must be set to false if
any of the following actions occur:</p>
<ul>
<li><p>The element's 2D context's <code
title="dom-context-2d-drawImage">drawImage()</code> method is
called with an <code>HTMLImageElement</code> or an
<code>HTMLVideoElement</code> whose <span>origin</span> is not the
<span title="same origin">same</span> as that of the
<code>Document</code> object that owns the <code>canvas</code>
element.</p></li>
<li><p>The element's 2D context's <code
title="dom-context-2d-drawImage">drawImage()</code> method is
called with an <code>HTMLCanvasElement</code> whose
<i>origin-clean</i> flag is false.</p></li>
<li><p>The element's 2D context's <code
title="dom-context-2d-fillStyle">fillStyle</code> attribute is set
to a <code>CanvasPattern</code> object that was created from an
<code>HTMLImageElement</code> or an <code>HTMLVideoElement</code>
whose <span>origin</span> was not the <span title="same
origin">same</span> as that of the <code>Document</code> object
that owns the <code>canvas</code> element when the pattern was
created.</p></li>
<li><p>The element's 2D context's <code
title="dom-context-2d-fillStyle">fillStyle</code> attribute is set
to a <code>CanvasPattern</code> object that was created from an
<code>HTMLCanvasElement</code> whose <i>origin-clean</i> flag was
false when the pattern was created.</p></li>
<li><p>The element's 2D context's <code
title="dom-context-2d-strokeStyle">strokeStyle</code> attribute is
set to a <code>CanvasPattern</code> object that was created from an
<code>HTMLImageElement</code> or an <code>HTMLVideoElement</code>
whose <span>origin</span> was not the <span title="same
origin">same</span> as that of the <code>Document</code> object
that owns the <code>canvas</code> element when the pattern was
created.</p></li>
<li><p>The element's 2D context's <code
title="dom-context-2d-strokeStyle">strokeStyle</code> attribute is
set to a <code>CanvasPattern</code> object that was created from an
<code>HTMLCanvasElement</code> whose <i>origin-clean</i> flag was
false when the pattern was created.</p></li>
</ul>
<p>Whenever the <code
title="dom-canvas-toDataURL">toDataURL()</code> method of a
<code>canvas</code> element whose <i>origin-clean</i> flag is set to
false is called, the method must raise a <code>SECURITY_ERR</code>
exception.</p>
<p>Whenever the <code
title="dom-context-2d-getImageData">getImageData()</code> method of
the 2D context of a <code>canvas</code> element whose
<i>origin-clean</i> flag is set to false is called with otherwise
correct arguments, the method must raise a <code>SECURITY_ERR</code>
exception.</p>
<p class="note">Even resetting the canvas state by changing its
<code title="attr-canvas-width">width</code> or <code
title="attr-canvas-height">height</code> attributes doesn't reset
the <i>origin-clean</i> flag.</p>
</div>
<h4>The <dfn><code>map</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd>When the element only contains <span>phrasing content</span>: <span>phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Transparent</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-map-name">name</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLMapElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-map-name">name</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-map-areas">areas</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-map-images">images</span>;
};</pre>
</dd>
</dl>
<p>The <code>map</code> element, in conjunction with any
<code>area</code> element descendants, defines an <span>image
map</span>. The element <span>represents</span> its children.</p>
<p>The <dfn title="attr-map-name"><code>name</code></dfn> attribute
gives the map a name so that it can be referenced. The attribute
must be present and must have a non-empty value with no <span
title="space character">space characters</span>. The value of the
<code title="attr-map-name">name</code> attribute must not be a
<span title="compatibility caseless">compatibility-caseless</span>
match for the value of the <code title="attr-map-name">name</code>
attribute of another <code>map</code> element in the same
document. If the <code title="attr-id">id</code> attribute is also
specified, both attributes must have the same value.</p>
<dl class="domintro">
<dt><var title="">map</var> . <code title="dom-map-areas">areas</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>area</code> elements in the <code>map</code>.</p>
</dd>
<dt><var title="">map</var> . <code title="dom-map-images">images</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>img</code> and <code>object</code> elements that use the <code>map</code>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-map-areas"><code>areas</code></dfn> attribute
must return an <code>HTMLCollection</code> rooted at the
<code>map</code> element, whose filter matches only
<code>area</code> elements.</p>
<p>The <dfn title="dom-map-images"><code>images</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only
<code>img</code> and <code>object</code> elements that are
associated with this <code>map</code> element according to the
<span>image map</span> processing model.</p>
<p>The IDL attribute <dfn
title="dom-map-name"><code>name</code></dfn> must
<span>reflect</span> the content attribute of the same name.</p>
</div>
<h4>The <dfn><code>area</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected, but only if there is a <code>map</code> element ancestor.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-area-alt">alt</code></dd>
<dd><code title="attr-area-coords">coords</code></dd>
<dd><code title="attr-area-shape">shape</code></dd>
<dd><code title="attr-hyperlink-href">href</code></dd>
<dd><code title="attr-hyperlink-target">target</code></dd>
<dd><code title="attr-hyperlink-ping">ping</code></dd>
<dd><code title="attr-hyperlink-rel">rel</code></dd>
<dd><code title="attr-hyperlink-media">media</code></dd>
<dd><code title="attr-hyperlink-hreflang">hreflang</code></dd>
<dd><code title="attr-hyperlink-type">type</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLAreaElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-area-alt">alt</span>;
attribute DOMString <span title="dom-area-coords">coords</span>;
attribute DOMString <span title="dom-area-shape">shape</span>;
stringifier attribute DOMString <span title="dom-area-href">href</span>;
attribute DOMString <span title="dom-area-target">target</span>;
attribute DOMString <span title="dom-area-ping">ping</span>;
attribute DOMString <span title="dom-area-rel">rel</span>;
readonly attribute DOMTokenList <span title="dom-area-relList">relList</span>;
attribute DOMString <span title="dom-area-media">media</span>;
attribute DOMString <span title="dom-area-hreflang">hreflang</span>;
attribute DOMString <span title="dom-area-type">type</span>;
// <span>URL decomposition IDL attributes</span>
attribute DOMString <span title="dom-area-protocol">protocol</span>;
attribute DOMString <span title="dom-area-host">host</span>;
attribute DOMString <span title="dom-area-hostname">hostname</span>;
attribute DOMString <span title="dom-area-port">port</span>;
attribute DOMString <span title="dom-area-pathname">pathname</span>;
attribute DOMString <span title="dom-area-search">search</span>;
attribute DOMString <span title="dom-area-hash">hash</span>;
};</pre>
</dd>
</dl>
<p>The <code>area</code> element <span>represents</span> either a
hyperlink with some text and a corresponding area on an <span>image
map</span>, or a dead area on an image map.</p>
<p>If the <code>area</code> element has an <code
title="attr-hyperlink-href">href</code> attribute, then the
<code>area</code> element represents a <span>hyperlink</span>. In
this case, the <dfn title="attr-area-alt"><code>alt</code></dfn>
attribute must be present. It specifies the text of the
hyperlink. Its value must be text that, when presented with the
texts specified for the other hyperlinks of the <span>image
map</span>, and with the alternative text of the image, but without
the image itself, provides the user with the same kind of choice as
the hyperlink would when used without its text but with its shape
applied to the image. The <code title="attr-area-alt">alt</code>
attribute may be left blank if there is another <code>area</code>
element in the same <span>image map</span> that points to the same
resource and has a non-blank <code title="attr-area-alt">alt</code>
attribute.</p>
<p>If the <code>area</code> element has no <code
title="attr-hyperlink-href">href</code> attribute, then the area
represented by the element cannot be selected, and the <code
title="attr-area-alt">alt</code> attribute must be omitted.</p>
<p>In both cases, the <code title="attr-area-shape">shape</code> and
<code title="attr-area-coords">coords</code> attributes specify the
area.</p>
<p>The <dfn title="attr-area-shape"><code>shape</code></dfn>
attribute is an <span>enumerated attribute</span>. The following
table lists the keywords defined for this attribute. The states
given in the first cell of the rows with keywords give the states to
which those keywords map. <span class="impl">Some of the keywords
are non-conforming, as noted in the last column.</span></p>
<table>
<thead>
<tr>
<th>State
<th>Keywords
<th class="impl">Notes
<tbody>
<tr>
<td rowspan=2><span title="attr-area-shape-circle">Circle state</span>
<td><dfn title="attr-area-shape-keyword-circle"><code>circle</code></dfn>
<td class="impl">
<tr>
<td class="impl"><dfn title="attr-area-shape-keyword-circ"><code>circ</code></dfn>
<td class="impl">Non-conforming
<tr>
<td><span title="attr-area-shape-default">Default state</span>
<td><dfn title="attr-area-shape-keyword-default"><code>default</code></dfn>
<td class="impl">
<tr>
<td rowspan=2><span title="attr-area-shape-poly">Polygon state</span>
<td><dfn title="attr-area-shape-keyword-poly"><code>poly</code></dfn>
<td class="impl">
<tr>
<td class="impl"><dfn title="attr-area-shape-keyword-polygon"><code>polygon</code></dfn>
<td class="impl">Non-conforming
<tr>
<td rowspan=2><span title="attr-area-shape-rect">Rectangle state</span>
<td><dfn title="attr-area-shape-keyword-rect"><code>rect</code></dfn>
<td class="impl">
<tr>
<td class="impl"><dfn title="attr-area-shape-keyword-rectangle"><code>rectangle</code></dfn>
<td class="impl">Non-conforming
</table>
<p>The attribute may be omitted. The <i>missing value default</i> is
the <span title="attr-area-shape-rect">rectangle</span> state.</p>
<p>The <dfn title="attr-area-coords"><code>coords</code></dfn>
attribute must, if specified, contain a <span>valid list of
integers</span>. This attribute gives the coordinates for the shape
described by the <code title="attr-area-shape">shape</code>
attribute. <span class="impl">The processing for this attribute is
described as part of the <span>image map</span> processing
model.</span></p>
<!-- v2: It was suggested by John S. Urban that coords should
support percentages as well as pixels, so that one could use the
same image map for images of various sizes. -->
<p>In the <dfn title="attr-area-shape-circle">circle state</dfn>,
<code>area</code> elements must have a <code
title="attr-area-coords">coords</code> attribute present, with three
integers, the last of which must be non-negative. The first integer
must be the distance in CSS pixels from the left edge of the image
to the center of the circle, the second integer must be the distance
in CSS pixels from the top edge of the image to the center of the
circle, and the third integer must be the radius of the circle,
again in CSS pixels.</p>
<p>In the <dfn title="attr-area-shape-default">default state</dfn>
state, <code>area</code> elements must not have a <code
title="attr-area-coords">coords</code> attribute. (The area is the
whole image.)</p>
<p>In the <dfn title="attr-area-shape-poly">polygon state</dfn>,
<code>area</code> elements must have a <code
title="attr-area-coords">coords</code> attribute with at least six
integers, and the number of integers must be even. Each pair of
integers must represent a coordinate given as the distances from the
left and the top of the image in CSS pixels respectively, and all
the coordinates together must represent the points of the polygon,
in order.</p>
<p>In the <dfn title="attr-area-shape-rect">rectangle state</dfn>,
<code>area</code> elements must have a <code
title="attr-area-coords">coords</code> attribute with exactly four
integers, the first of which must be less than the third, and the
second of which must be less than the fourth. The four points must
represent, respectively, the distance from the left edge of the
image to the left side of the rectangle, the distance from the
top edge to the top side, the distance from the left edge to the
right side, and the distance from the top edge to the bottom side,
all in CSS pixels.</p>
<div class="impl">
<p>When user agents allow users to <span title="following
hyperlinks">follow hyperlinks</span> created using the
<code>area</code> element, as described in the next section, the
<code title="attr-hyperlink-href">href</code>,
<code title="attr-hyperlink-target">target</code> and <code
title="attr-hyperlink-ping">ping</code> attributes decide how the
link is followed. The <code title="attr-hyperlink-rel">rel</code>,
<code title="attr-hyperlink-media">media</code>, <code
title="attr-hyperlink-hreflang">hreflang</code>, and <code
title="attr-hyperlink-type">type</code> attributes may be used to
indicate to the user the likely nature of the target resource before
the user follows the link.</p>
</div>
<p>The <code title="attr-hyperlink-target">target</code>, <code
title="attr-hyperlink-ping">ping</code>, <code
title="attr-hyperlink-rel">rel</code>, <code
title="attr-hyperlink-media">media</code>, <code
title="attr-hyperlink-hreflang">hreflang</code>, and <code
title="attr-hyperlink-type">type</code> attributes must be omitted
if the <code title="attr-hyperlink-href">href</code> attribute is
not present.</p>
<div class="impl">
<p>The <span>activation behavior</span> of <code>area</code>
elements is to run the following steps:</p>
<ol>
<li><p>If the <code title="event-DOMActivate">DOMActivate</code>
event in question is not <span
title="concept-events-trusted">trusted</span> (i.e. a <code
title="dom-click">click()</code> method call was the reason for the
event being dispatched), and the <code>area</code> element's <code
title="attr-hyperlink-target">target</code> attribute is such that
applying <span>the rules for choosing a browsing context given a
browsing context name</span>, using the value of the <code
title="attr-hyperlink-target">target</code> attribute as the
browsing context name, would result in there not being a chosen
browsing context, then raise an <code>INVALID_ACCESS_ERR</code>
exception and abort these steps.</p></li>
<li>Otherwise, the user agent must <span title="following
hyperlinks">follow the hyperlink</span> defined by the
<code>area</code> element, if any.</li>
</ol>
<p>The IDL attributes <dfn
title="dom-area-alt"><code>alt</code></dfn>, <dfn
title="dom-area-coords"><code>coords</code></dfn>, <dfn
title="dom-area-href"><code>href</code></dfn>, <dfn
title="dom-area-target"><code>target</code></dfn>, <dfn
title="dom-area-ping"><code>ping</code></dfn>, <dfn
title="dom-area-rel"><code>rel</code></dfn>, <dfn
title="dom-area-media"><code>media</code></dfn>, <dfn
title="dom-area-hreflang"><code>hreflang</code></dfn>, and <dfn
title="dom-area-type"><code>type</code></dfn>, each must
<span>reflect</span> the respective content attributes of the same
name.</p>
<p>The IDL attribute <dfn
title="dom-area-shape"><code>shape</code></dfn> must
<span>reflect</span> the <code title="attr-area-shape">shape</code>
content attribute, <span>limited to only known values</span>.</p>
<p>The IDL attribute <dfn
title="dom-area-rellist"><code>relList</code></dfn> must
<span>reflect</span> the <code title="attr-hyperlink-rel">rel</code>
content attribute.</p>
<p>The <code>area</code> element also supports the complement of
<span>URL decomposition IDL attributes</span>, <dfn
title="dom-area-protocol"><code>protocol</code></dfn>, <dfn
title="dom-area-host"><code>host</code></dfn>, <dfn
title="dom-area-port"><code>port</code></dfn>, <dfn
title="dom-area-hostname"><code>hostname</code></dfn>, <dfn
title="dom-area-pathname"><code>pathname</code></dfn>, <dfn
title="dom-area-search"><code>search</code></dfn>, and <dfn
title="dom-area-hash"><code>hash</code></dfn>. These must follow the
rules given for URL decomposition IDL attributes, with the <span
title="concept-uda-input">input</span> being the result of <span
title="resolve a url">resolving</span> the element's <code
title="attr-hyperlink-href">href</code> attribute relative to the
element, if there is such an attribute and resolving it is
successful, or the empty string otherwise; and the <span
title="concept-uda-setter">common setter action</span> being the
same as setting the element's <code
title="attr-hyperlink-href">href</code> attribute to the new output
value.</p>
</div>
<h4 id="image-maps">Image maps</h4>
<!-- TESTS
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E%0A%3Cimg%20src%3D%22http%3A//hixie.ch/resources/images/smallcats%22%20usemap%3D%23a%20onclick%3Dw%28%27img%27%29%3E%0A%3Cmap%20name%3Da%3E%0A%20%3Carea%20onclick%3Dw%28%271%27%29%20coords%3D%270%25%200%25%20100%25%20100%25%27%20href%3Djavascript%3A%3E%0A%3C/map%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E%0A%3Cbody%20onfocus%3D%22w%28document.activeElement.tagName%29%22%3E%0A%3Cimg%20src%3D%22http%3A//hixie.ch/resources/images/smallcats%22%20usemap%3D%23a%20onclick%3Dw%28%27img%27%29%20onfocus%3D%22w%28document.activeElement.tagName%29%22%3E%0A%3Cimg%20src%3D%22http%3A//hixie.ch/resources/images/sample%22%20usemap%3D%23a%20onclick%3Dw%28%27img%27%29%20onfocus%3D%22w%28document.activeElement.tagName%29%22%3E%0A%3Cmap%20name%3Da%20onfocus%3D%22w%28document.activeElement.tagName%29%22%3E%0A%20%3Carea%20onclick%3Dw%28%271%27%29%20coords%3D%270%200%2050%2050%27%20href%3Djavascript%3A%20onfocus%3D%22w%28document.activeElement.tagName%29%22%3E%0A%3C/map%3E%0A%3Cscript%3E%0A%20var%20x%20%3D%20document.getElementsByTagName%28%27img%27%29%5B0%5D%3B%0A%20x.parentNode.appendChild%28x%29%3B%0A%20document.getElementsByTagName%28%27area%27%29%5B0%5D.focus%28%29%3B%0A%3C/script%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3Ex%3Cmap%3E%3Carea%20shape%3Dpolyg%20coords%3D%221%2C2%203%22%3E%3C/map%3E%0A%3Cscript%3Ex%20%3D%20document.getElementsByTagName%28%27area%27%29%5B0%5D%3B%20w%28x.shape%20+%20%27%20%27%20+%20x.coords%29%3C/script%3E
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E%0D%0A%3Cp%3E%3Cimg%20src%3D%22http%3A//hixie.ch/resources/images/astrophy/128%22%20usemap%3D%23a%3E%0D%0A%3Cmap%20name%3Da%3E%3Carea%20shape%3Dcirc%20coords%3D%2220%2C20%2C10%25%22%20href%3D%23%3E%3Carea%20shape%3Dcirc%20coords%3D%2220%2C20%2C10%22%20href%3D%23%3E%3C/map%3E%0D%0A%3Cscript%3Edocument.write%28document.getElementsByTagName%28%27area%27%29%5B0%5D.coords%29%3C/script%3E
-->
<div class="impl">
<h5>Authoring</h5>
</div>
<p>An <dfn>image map</dfn> allows geometric areas on an image to be
associated with <span title="hyperlink">hyperlinks</span>.</p>
<p>An image, in the form of an <code>img</code> element or an
<code>object</code> element representing an image, may be associated
with an image map (in the form of a <code>map</code> element) by
specifying a <dfn
title="attr-hyperlink-usemap"><code>usemap</code></dfn> attribute on
the <code>img</code> or <code>object</code> element. The <code
title="attr-hyperlink-usemap">usemap</code> attribute, if specified,
must be a <span>valid hash-name reference</span> to a
<code>map</code> element.</p>
<div class="example">
<p>Consider an image that looks as follows:</p>
<p><img src="images/sample-usemap.png" alt="A line with four shapes in it, equally spaced: a red hollow box, a green circle, a blue triangle, and a yellow four-pointed star."></p>
<p>If we wanted just the colored areas to be clickable, we could
do it as follows:</p>
<pre><p>
Please select a shape:
<img src="shapes.png" usemap="#shapes"
alt="Four shapes are available: a red hollow box, a green circle, a blue triangle, and a yellow four-pointed star.">
<map name="shapes">
<area shape=rect coords="50,50,100,100"> <!-- the hole in the red box -->
<area shape=rect coords="25,25,125,125" href="red.html" alt="Red box.">
<area shape=circle coords="200,75,50" href="green.html" alt="Green circle.">
<area shape=poly coords="325,25,262,125,388,125" href="blue.html" alt="Blue triangle.">
<area shape=poly coords="450,25,435,60,400,75,435,90,450,125,465,90,500,75,465,60"
href="yellow.html" alt="Yellow star.">
</map>
</p></pre>
</div>
<div class="impl">
<h5>Processing model</h5>
<p>If an <code>img</code> element or an <code>object</code> element
representing an image has a <code
title="attr-hyperlink-usemap">usemap</code> attribute specified,
user agents must process it as follows:</p>
<ol>
<li><p>First, <span>rules for parsing a hash-name reference</span>
to a <code>map</code> element must be followed. This will return
either an element (the <var title="">map</var>) or null.</p></li>
<li><p>If that returned null, then abort these steps. The image is
not associated with an image map after all.</p></li>
<li><p>Otherwise, the user agent must collect all the
<code>area</code> elements that are descendants of the <var
title="">map</var>. Let those be the <var
title="">areas</var>.</p></li>
</ol>
<p>Having obtained the list of <code>area</code> elements that form
the image map (the <var title="">areas</var>), interactive user
agents must process the list in one of two ways.</p>
<p>If the user agent intends to show the text that the
<code>img</code> element represents, then it must use the following
steps.</p>
<p class="note">In user agents that do not support images, or that
have images disabled, <code>object</code> elements cannot represent
images, and thus this section never applies (the <span>fallback
content</span> is shown instead). The following steps therefore only
apply to <code>img</code> elements.</p>
<ol>
<li><p>Remove all the <code>area</code> elements in <var
title="">areas</var> that have no <code
title="attr-hyperlink-href">href</code> attribute.</p></li>
<li><p>Remove all the <code>area</code> elements in <var
title="">areas</var> that have no <code
title="attr-area-alt">alt</code> attribute, or whose <code
title="attr-area-alt">alt</code> attribute's value is the empty
string, <em>if</em> there is another <code>area</code> element in
<var title="">areas</var> with the same value in the <code
title="attr-hyperlink-href">href</code> attribute and with a
non-empty <code title="attr-area-alt">alt</code> attribute.</li>
<li><p>Each remaining <code>area</code> element in <var
title="">areas</var> represents a <span>hyperlink</span>. Those
hyperlinks should all be made available to the user in a manner
associated with the text of the <code>img</code>.</p>
<p>In this context, user agents may represent <code>area</code> and
<code>img</code> elements with no specified <code
title="">alt</code> attributes, or whose <code title="">alt</code>
attributes are the empty string or some other non-visible text, in
a user-agent-defined fashion intended to indicate the lack of
suitable author-provided text.</p></li>
</ol>
<p>If the user agent intends to show the image and allow interaction
with the image to select hyperlinks, then the image must be
associated with a set of layered shapes, taken from the
<code>area</code> elements in <var title="">areas</var>, in reverse
tree order (so the last specified <code>area</code> element in the
<var title="">map</var> is the bottom-most shape, and the first
element in the <var title="">map</var>, in tree order, is the
top-most shape).</p>
<p>Each <code>area</code> element in <var title="">areas</var> must
be processed as follows to obtain a shape to layer onto the
image:</p>
<ol>
<li><p>Find the state that the element's <code
title="attr-area-shape">shape</code> attribute represents.</p></li>
<li><p>Use the <span>rules for parsing a list of integers</span> to
parse the element's <code title="attr-area-coords">coords</code>
attribute, if it is present, and let the result be the <var
title="">coords</var> list. If the attribute is absent, let the
<var title="">coords</var> list be the empty list.</p></li>
<li><p>If the number of items in the <var title="">coords</var>
list is less than the minimum number given for the
<code>area</code> element's current state, as per the following
table, then the shape is empty; abort these steps.</p>
<table>
<thead>
<tr>
<th>State
<th>Minimum number of items
<tbody>
<tr>
<td><span title="attr-area-shape-circle">Circle state</span>
<td>3
<tr>
<td><span title="attr-area-shape-default">Default state</span>
<td>0
<tr>
<td><span title="attr-area-shape-poly">Polygon state</span>
<td>6
<tr>
<td><span title="attr-area-shape-rect">Rectangle state</span>
<td>4
</table>
</li>
<li><p>Check for excess items in the <var title="">coords</var>
list as per the entry in the following list corresponding to the
<code title="attr-area-shape">shape</code> attribute's state:</p>
<dl class="switch">
<dt><span title="attr-area-shape-circle">Circle state</span></dt>
<dd>Drop any items in the list beyond the third.</dd>
<dt><span title="attr-area-shape-default">Default state</span></dt>
<dd>Drop all items in the list.</dd>
<dt><span title="attr-area-shape-poly">Polygon state</span></dt>
<dd>Drop the last item if there's an odd number of items.</dd>
<dt><span title="attr-area-shape-rect">Rectangle state</span></dt>
<dd>Drop any items in the list beyond the fourth.</dd>
</dl>
</li>
<li><p>If the <code title="attr-area-shape">shape</code> attribute
represents the <span title="attr-area-shape-rect">rectangle
state</span>, and the first number in the list is numerically less
than the third number in the list, then swap those two numbers
around.</p></li>
<li><p>If the <code title="attr-area-shape">shape</code> attribute
represents the <span title="attr-area-shape-rect">rectangle
state</span>, and the second number in the list is numerically less
than the fourth number in the list, then swap those two numbers
around.</p></li>
<li><p>If the <code title="attr-area-shape">shape</code> attribute
represents the <span title="attr-area-shape-circle">circle
state</span>, and the third number in the list is less than or
equal to zero, then the shape is empty; abort these steps.</p></li>
<li><p>Now, the shape represented by the element is the one
described for the entry in the list below corresponding to the
state of the <code title="attr-area-shape">shape</code>
attribute:</p>
<dl class="switch">
<dt><span title="attr-area-shape-circle">Circle state</span></dt>
<dd>
<p>Let <var title="">x</var> be the first number in <var
title="">coords</var>, <var title="">y</var> be the second
number, and <var title="">r</var> be the third number.</p>
<p>The shape is a circle whose center is <var title="">x</var>
CSS pixels from the left edge of the image and <var
title="">x</var> CSS pixels from the top edge of the image, and
whose radius is <var title="">r</var> pixels.</p>
</dd>
<dt><span title="attr-area-shape-default">Default state</span></dt>
<dd>
<p>The shape is a rectangle that exactly covers the entire
image.</p>
</dd>
<dt><span title="attr-area-shape-poly">Polygon state</span></dt>
<dd>
<p>Let <var title="">x<sub title=""><var
title="">i</var></sub></var> be the <span title="">(2<var
title="">i</var>)</span>th entry in <var title="">coords</var>,
and <var title="">y<sub title=""><var
title="">i</var></sub></var> be the <span title="">(2<var
title="">i</var>+1)</span>th entry in <var title="">coords</var>
(the first entry in <var title="">coords</var> being the one
with index 0).</p>
<p>Let <var title="">the coordinates</var> be (<var
title="">x<sub title=""><var title="">i</var></sub></var>, <var
title="">y<sub title=""><var title="">i</var></sub></var>),
interpreted in CSS pixels measured from the top left of the
image, for all integer values of <var title="">i</var> from 0 to
<span title="">(<var title="">N</var>/2)-1</span>, where <var
title="">N</var> is the number of items in <var
title="">coords</var>.</p>
<p>The shape is a polygon whose vertices are given by <var
title="">the coordinates</var>, and whose interior is
established using the even-odd rule. <a
href="#refsGRAPHICS">[GRAPHICS]</a></p>
<!--
browsers implement the even-odd rule / even winding rule:
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E%0A%3Cimg%20usemap%3D%22%23x%22%20src%3D%22/resources/images/sample%22%3E%0A%3Cmap%20name%3D%22x%22%3E%0A%20%20%3Carea%20shape%3Dpolygon%20coords%3D%220%2C0%200%2C100%20100%2C100%20100%2C2%201%2C2%202%2C1%202%2C99%2099%2C99%2099%2C0%22%20href%3Da%3E%0A%3C/map%3E%0A
-->
</dd>
<dt><span title="attr-area-shape-rect">Rectangle state</span></dt>
<dd>
<p>Let <var title="">x<sub title="">1</sub></var> be the first
number in <var title="">coords</var>, <var title="">y<sub
title="">1</sub></var> be the second number, <var title="">x<sub
title="">2</sub></var> be the third number, and <var
title="">y<sub title="">2</sub></var> be the fourth number.</p>
<p>The shape is a rectangle whose top-left corner is given by
the coordinate (<var title="">x<sub title="">1</sub></var>, <var
title="">y<sub title="">1</sub></var>) and whose bottom right
corner is given by the coordinate (<var title="">x<sub
title="">2</sub></var>, <var title="">y<sub
title="">2</sub></var>), those coordinates being interpreted as
CSS pixels from the top left corner of the image.</p>
</dd>
</dl>
<p>For historical reasons, the coordinates must be interpreted
relative to the <em>displayed</em> image, even if it stretched
using CSS or the image element's <code title="">width</code> and
<code title="">height</code> attributes.</p>
</li>
</ol>
<p>Mouse clicks on an image associated with a set of layered shapes
per the above algorithm must be dispatched to the top-most shape
covering the point that the pointing device indicated (if any), and
then, must be dispatched again (with a new <code>Event</code>
object) to the image element itself. User agents may also allow
individual <code>area</code> elements representing <span
title="hyperlink">hyperlinks</span> to be selected and activated
(e.g. using a keyboard); events from this are not also propagated to
the image.</p>
<p class="note">Because a <code>map</code> element (and its
<code>area</code> elements) can be associated with multiple
<code>img</code> and <code>object</code> elements, it is possible
for an <code>area</code> element to correspond to multiple focusable
areas of the document.</p>
<p>Image maps are <em>live</em>; if the DOM is mutated, then the
user agent must act as if it had rerun the algorithms for image
maps.</p>
</div>
<h4>MathML</h4>
<p>The <dfn><code>math</code></dfn> element from the <span>MathML
namespace</span> falls into the <span>embedded content</span>,
<span>phrasing content</span>, and <span>flow content</span>
categories for the purposes of the content models in this
specification.</p>
<div class="impl">
<!-- apparently we get to define error handling, so: -->
<p>User agents must handle text other than <span>inter-element
whitespace</span> found in MathML elements whose content models do
not allow straight text by pretending for the purposes of MathML
content models, layout, and rendering that that text is actually
wrapped in an <code title="">mtext</code> element in the
<span>MathML namespace</span>. (Such text is not, however,
conforming.)</p>
<p>User agents must act as if any MathML element whose contents does
not match the element's content model was replaced, for the purposes
of MathML layout and rendering, by an <code title="">merror</code>
element in the <span>MathML namespace</span> containing some
appropriate error message.</p>
<p>To enable authors to use MathML tools that only accept MathML in
its XML form, interactive HTML user agents are encouraged to provide
a way to export any MathML fragment as an XML namespace-well-formed
XML fragment.</p>
</div>
<p>The semantics of MathML elements are defined by the MathML
specification and other relevant specifications. <a
href="#refsMATHML">[MATHML]</a></p>
<div class="example">
<p>Here is an example of the use of MathML in an HTML document:</p>
<pre><!DOCTYPE html>
<html>
<head>
<title>The quadratic formula</title>
</head>
<body>
<h1>The quadratic formula</h1>
<p>
<math>
<mi>x</mi>
<mo>=</mo>
<mfrac>
<mrow>
<mo form="prefix">−</mo> <mi>b</mi>
<mo>±</mo>
<msqrt>
<msup> <mi>b</mi> <mn>2</mn> </msup>
<mo>−</mo>
<mn>4</mn> <mo>⁢</mo> <mi>a</mi> <mo>⁢</mo> <mi>c</mi>
</msqrt>
</mrow>
<mrow>
<mn>2</mn> <mo>⁢</mo> <mi>a</mi>
</mrow>
</mfrac>
</math>
</p>
</body>
</html></pre>
</div>
<h4>SVG</h4>
<p>The <dfn><code>svg</code></dfn> element from the <span>SVG
namespace</span> falls into the <span>embedded content</span>,
<span>phrasing content</span>, and <span>flow content</span>
categories for the purposes of the content models in this
specification.</p>
<div class="impl">
<p>To enable authors to use SVG tools that only accept SVG in its
XML form, interactive HTML user agents are encouraged to provide a
way to export any SVG fragment as an XML namespace-well-formed XML
fragment.</p>
</div>
<p>When the SVG <code>foreignObject</code> element contains elements
from the <span>HTML namespace</span>, such elements must all be
<span>flow content</span>. <a href="#refsSVG">[SVG]</a></p>
<p>The content model for <code title="">title</code> elements in the
<span>SVG namespace</span> inside <span>HTML documents</span> is
<span>phrasing content</span>. (This further constrains the
requirements given in the SVG specification.)</p>
<p>The semantics of SVG elements are defined by the SVG
specification and other relevant specifications. <a
href="#refsSVG">[SVG]</a></p>
<!-- The following paragraph is for bug 7510 -->
<p>The SVG specification includes requirements regarding the
handling of elements in the DOM that are not in the SVG namespace,
that are in SVG fragments, and that are not included in a
<code>foreignObject</code> element. <em>This</em> specification does
not define any processing for elements in SVG fragments that are not
in the HTML namespace; they are considered neither conforming nor
non-conforming from the perspective of this specification.</p>
<h4><dfn>Dimension attributes</dfn></h4>
<p><span class="impl"><strong>Author requirements</strong>:</span>
The <dfn title="attr-dim-width"><code>width</code></dfn> and <dfn
title="attr-dim-height"><code>height</code></dfn> attributes on
<code>img</code>, <code>iframe</code>, <code>embed</code>,
<code>object</code>, <code>video</code>, and, when their <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-image">Image Button</span> state,
<code>input</code> elements may be specified to give the dimensions
of the visual content of the element (the width and height
respectively, relative to the nominal direction of the output
medium), in CSS pixels. The attributes, if specified, must have
values that are <span title="valid non-negative integer">valid
non-negative integers</span>.</p>
<p>The specified dimensions given may differ from the dimensions
specified in the resource itself, since the resource may have a
resolution that differs from the CSS pixel resolution. (On screens,
CSS pixels have a resolution of 96ppi, but in general the CSS pixel
resolution depends on the reading distance.) If both attributes are
specified, then one of the following statements must be true:</p>
<ul>
<li><span title=""><var title="">specified width</var> - 0.5 ≤
<var title="">specified height</var> * <var title="">target ratio</var> ≤
<var title="">specified width</var> + 0.5</span></li>
<li><span title=""><var title="">specified height</var> - 0.5 ≤
<var title="">specified width</var> / <var title="">target ratio</var> ≤
<var title="">specified height</var> + 0.5</span></li>
<li><span title=""><var title="">specified height</var> = <var title="">specified width</var> = 0</span></li>
</ul>
<p>The <var title="">target ratio</var> is the ratio of the
intrinsic width to the intrinsic height in the resource. The <var
title="">specified width</var> and <var title="">specified
height</var> are the values of the <code
title="attr-dim-width">width</code> and <code
title="attr-dim-height">height</code> attributes respectively.</p>
<p>The two attributes must be omitted if the resource in question
does not have both an intrinsic width and an intrinsic height.</p>
<p>If the two attributes are both zero, it indicates that the
element is not intended for the user (e.g. it might be a part of a
service to count page views).</p>
<p class="note">The dimension attributes are not intended to be used
to stretch the image.</p>
<div class="impl">
<p><strong>User agent requirements</strong>: User agents are
expected to use these attributes <a href="#dimRendering">as hints
for the rendering</a>.</p>
<p>The <dfn title="dom-dim-width"><code>width</code></dfn> and <dfn
title="dom-dim-height"><code>height</code></dfn> IDL attributes on
the <code>iframe</code>, <code>embed</code>, <code>object</code>,
and <code>video</code> elements must <span>reflect</span> the
respective content attributes of the same name.</p>
</div>
<h3>Tabular data</h3>
<h4>The <dfn><code>table</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>In this order: optionally a <code>caption</code> element,
followed by either zero or more <code>colgroup</code> elements,
followed optionally by a <code>thead</code> element, followed
optionally by a <code>tfoot</code> element, followed by either zero
or more <code>tbody</code> elements or one or more <code>tr</code>
elements, followed optionally by a <code>tfoot</code> element (but
there can only be one <code>tfoot</code> element child in
total).</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-table-summary">summary</code> (but see prose)</dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTableElement</dfn> : <span>HTMLElement</span> {
attribute <span>HTMLTableCaptionElement</span> <span title="dom-table-caption">caption</span>;
<span>HTMLElement</span> <span title="dom-table-createCaption">createCaption</span>();
void <span title="dom-table-deleteCaption">deleteCaption</span>();
attribute <span>HTMLTableSectionElement</span> <span title="dom-table-tHead">tHead</span>;
<span>HTMLElement</span> <span title="dom-table-createTHead">createTHead</span>();
void <span title="dom-table-deleteTHead">deleteTHead</span>();
attribute <span>HTMLTableSectionElement</span> <span title="dom-table-tFoot">tFoot</span>;
<span>HTMLElement</span> <span title="dom-table-createTFoot">createTFoot</span>();
void <span title="dom-table-deleteTFoot">deleteTFoot</span>();
readonly attribute <span>HTMLCollection</span> <span title="dom-table-tBodies">tBodies</span>;
<span>HTMLElement</span> <span title="dom-table-createTBody">createTBody</span>();
readonly attribute <span>HTMLCollection</span> <span title="dom-table-rows">rows</span>;
<span>HTMLElement</span> <span title="dom-table-insertRow">insertRow</span>(in optional long index);
void <span title="dom-table-deleteRow">deleteRow</span>(in long index);
attribute DOMString <span title="dom-table-summary">summary</span>;
};</pre>
</dd>
</dl>
<p>The <code>table</code> element <span>represents</span> data with
more than one dimension, in the form of a <span
title="concept-table">table</span>.</p>
<div class="impl">
<p>The <code>table</code> element takes part in the <span>table
model</span>.</p>
</div>
<p>Tables must not be used as layout aids. Historically, some Web
authors have misused tables in HTML as a way to control their page
layout. This usage is non-conforming, because tools attempting to
extract tabular data from such documents would obtain very confusing
results. In particular, users of accessibility tools like screen
readers are likely to find it very difficult to navigate pages with
tables used for layout.</p>
<p class="note">There are a variety of alternatives to using HTML
tables for layout, primarily using CSS positioning and the CSS table
model.</p>
<div class="impl">
<p>User agents that do table analysis on arbitrary content are
encouraged to find heuristics to determine which tables actually
contain data and which are merely being used for layout. This
specification does not define a precise heuristic.</p>
</div>
<p>Tables have rows and columns given by their descendants. A table
must not have an empty row or column<span class="impl">, as
described in the description of the <span>table
model</span></span>. <!-- conformance criteria for detecting this
are in the table model section --></p>
<p id="table-descriptions">For tables that consist of more than just
a grid of cells with headers in the first row and headers in the
first column, and for any table in general where the reader might
have difficulty understanding the content, authors should include
explanatory information introducing the table. This information is
useful for all users, but is especially useful for users who cannot
see the table, e.g. users of screen readers.</p>
<p>Such explanatory information should introduce the purpose of the
table, outline its basic cell structure, highlight any trends or
patterns, and generally teach the user how to use the table.</p>
<div class="example">
<p>For instance, the following table:</p>
<table>
<caption>Characteristics with positive and negative sides</caption>
<thead>
<tr>
<th id="n"> Negative
<th> Characteristic
<th> Positive
<tbody>
<tr>
<td headers="n r1"> Sad
<th id=r1> Mood
<td> Happy
<tr>
<td headers="n r2"> Failing
<th id=r2> Grade
<td> Passing
</table>
<p>...might benefit from a description explaining the way the table
is laid out, something like "Characteristics are given in the
second column, with the negative side in the left column and the
positive side in the right column".</p>
</div>
<p>There are a variety of ways to include this information, such as:</p>
<dl>
<dt>In prose, surrounding the table</dt>
<dd>
<div class="example"><pre><p>In the following table, characteristics are given in the second
column, with the negative side in the left column and the positive
side in the right column.</p>
<table>
<caption>Characteristics with positive and negative sides</caption>
<thead>
<tr>
<th id="n"> Negative
<th> Characteristic
<th> Positive
<tbody>
<tr>
<td headers="n r1"> Sad
<th id="r1"> Mood
<td> Happy
<tr>
<td headers="n r2"> Failing
<th id="r2"> Grade
<td> Passing
</table></pre></div>
</dd>
<dt>In the table's <code>caption</code></dt>
<dd>
<div class="example"><pre><table>
<caption>
<strong>Characteristics with positive and negative sides.</strong>
<p>Characteristics are given in the second column, with the
negative side in the left column and the positive side in the right
column.</p>
</caption>
<thead>
<tr>
<th id="n"> Negative
<th> Characteristic
<th> Positive
<tbody>
<tr>
<td headers="n r1"> Sad
<th id="r1"> Mood
<td> Happy
<tr>
<td headers="n r2"> Failing
<th id="r2"> Grade
<td> Passing
</table></pre></div>
</dd>
<dt>In the table's <code>caption</code>, in a <code>details</code> element</dt>
<dd>
<div class="example"><pre><table>
<caption>
<strong>Characteristics with positive and negative sides.</strong>
<details>
<dt>Help</dt>
<dd>
<p>Characteristics are given in the second column, with the
negative side in the left column and the positive side in the right
column.</p>
</dd>
</details>
</caption>
<thead>
<tr>
<th id="n"> Negative
<th> Characteristic
<th> Positive
<tbody>
<tr>
<td headers="n r1"> Sad
<th id="r1"> Mood
<td> Happy
<tr>
<td headers="n r2"> Failing
<th id="r2"> Grade
<td> Passing
</table></pre></div>
</dd>
<dt>Next to the table, in the same <code>figure</code></dt>
<dd>
<div class="example"><pre><figure>
<dt>Characteristics with positive and negative sides</dt>
<dd>
<p>Characteristics are given in the second column, with the
negative side in the left column and the positive side in the right
column.</p>
<table>
<thead>
<tr>
<th id="n"> Negative
<th> Characteristic
<th> Positive
<tbody>
<tr>
<td headers="n r1"> Sad
<th id="r1"> Mood
<td> Happy
<tr>
<td headers="n r2"> Failing
<th id="r2"> Grade
<td> Passing
</table>
</dd>
</figure></pre></div>
</dd>
<dt>Next to the table, in a <code>figure</code>'s <code>dt</code></dt>
<dd>
<div class="example"><pre><figure>
<dt>
<strong>Characteristics with positive and negative sides</strong>
<p>Characteristics are given in the second column, with the
negative side in the left column and the positive side in the right
column.</p>
</dt>
<dd>
<table>
<thead>
<tr>
<th id="n"> Negative
<th> Characteristic
<th> Positive
<tbody>
<tr>
<td headers="n r1"> Sad
<th id="r1"> Mood
<td> Happy
<tr>
<td headers="n r2"> Failing
<th id="r2"> Grade
<td> Passing
</table>
</dd>
</figure></pre></div>
</dd>
</dl>
<p>Authors may also use other techniques, or combinations of the
above techniques, as appropriate.</p>
<p>The best option, of course, rather than writing a description
explaining the way the table is laid out, is to adjust the table
such that no explanation is needed.</p>
<div class="example">
<p>In the case of the table used in the examples above, a simple
rearrangement of the table so that the headers are on the top and
left sides removes the need for an explanation as well as removing
the need for the use of <code
title="attr-tdth-headers">headers</code> attributes:</p>
<pre><table>
<caption>Characteristics with positive and negative sides</caption>
<thead>
<tr>
<th> Characteristic
<th> Negative
<th> Positive
<tbody>
<tr>
<th> Mood
<td> Sad
<td> Happy
<tr>
<th> Grade
<td> Failing
<td> Passing
</table></pre>
</div>
<p>The <dfn title="attr-table-summary"><code>summary</code></dfn>
attribute on <code>table</code> elements was suggested in earlier
versions of the language as a technique for providing explanatory
text for complex tables for users of screen readers. One of the <a
href="#table-descriptions">techniques</a> described <!--in the
<code>table</code> section--> above should be used
instead. <!--Authors should not specify the <code
title="attr-table-summary">summary</code> attribute on
<code>table</code> elements. --> <!-- 2.65% pages --></p>
<p class="note">In particular, authors are encouraged to consider
whether their explanatory text for tables is likely to be useful to
the visually impaired: if their text would not be useful, then it is
best to not include a <code
title="attr-table-summary">summary</code> attribute. Similarly, if
their explanatory text could help someone who is not visually
impaired, e.g. someone who is seeing the table for the first time,
then the text would be more useful before the table or in the
<code>caption</code>. For example, describing the conclusions of the
data in a table is useful to everyone; explaining how to read the
table, if not obvious from the headers alone, is useful to everyone;
describing the structure of the table, if it is easy to grasp
visually, may not be useful to everyone, but it might also not be
useful to users who can quickly navigate the table with an
accessibility tool.</p>
<!--
<p class="note">Use of the <code
title="attr-table-summary">summary</code> attribute is discouraged
because in practice it is poorly understood. Because the attribute
is not exposed in visual user agents, authors who have included it
have typically not been able to test it, and have therefore set the
attribute to values that are of no use to users of accessibility
tools. This has lead to accessibility tools introducing heuristics
to try to avoid exposing such usage of the attribute to users. Even
the few authors who have made the best use of the attribute have
often misused it, for example by including text that would in fact
be useful for all users, or that is redundant with other information
on the page separate from the table.</p>
-->
<div class="impl">
<p>If a <code>table</code> element has a <code
title="attr-table-summary">summary</code> attribute, the user agent
may report the contents of that attribute to the user.</p>
</div>
<dl class="domintro">
<dt><var title="">table</var> . <code title="dom-table-caption">caption</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the table's <code>caption</code> element.</p>
<p>Can be set, to replace the <code>caption</code> element. If the
new value is not a <code>caption</code> element, throws a
<code>HIERARCHY_REQUEST_ERR</code> exception.</p>
<dd>
<dt><var title="">caption</var> = <var title="">table</var> . <code title="dom-table-createCaption">createCaption</code>()</dt>
<dd>
<p>Ensures the table has a <code>caption</code> element, and returns it.</p>
<dd>
<dt><var title="">table</var> . <code title="dom-table-deleteCaption">deleteCaption</code>()</dt>
<dd>
<p>Ensures the table does not have a <code>caption</code> element.</p>
<dd>
<dt><var title="">table</var> . <code title="dom-table-tHead">tHead</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the table's <code>thead</code> element.</p>
<p>Can be set, to replace the <code>thead</code> element. If the
new value is not a <code>thead</code> element, throws a
<code>HIERARCHY_REQUEST_ERR</code> exception.</p>
<dd>
<dt><var title="">thead</var> = <var title="">table</var> . <code title="dom-table-createTHead">createTHead</code>()</dt>
<dd>
<p>Ensures the table has a <code>thead</code> element, and returns it.</p>
<dd>
<dt><var title="">table</var> . <code title="dom-table-deleteTHead">deleteTHead</code>()</dt>
<dd>
<p>Ensures the table does not have a <code>thead</code> element.</p>
<dd>
<dt><var title="">table</var> . <code title="dom-table-tFoot">tFoot</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the table's <code>tfoot</code> element.</p>
<p>Can be set, to replace the <code>tfoot</code> element. If the
new value is not a <code>tfoot</code> element, throws a
<code>HIERARCHY_REQUEST_ERR</code> exception.</p>
<dd>
<dt><var title="">tfoot</var> = <var title="">table</var> . <code title="dom-table-createTFoot">createTFoot</code>()</dt>
<dd>
<p>Ensures the table has a <code>tfoot</code> element, and returns it.</p>
<dd>
<dt><var title="">table</var> . <code title="dom-table-deleteTFoot">deleteTFoot</code>()</dt>
<dd>
<p>Ensures the table does not have a <code>tfoot</code> element.</p>
<dd>
<dt><var title="">table</var> . <code title="dom-table-tBodies">tBodies</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>tbody</code> elements of the table.</p>
<dd>
<dt><var title="">tbody</var> = <var title="">table</var> . <code title="dom-table-createTBody">createTBody</code>()</dt>
<dd>
<p>Creates a <code>tbody</code> element, inserts it into the table, and returns it.</p>
<dd>
<dt><var title="">table</var> . <code title="dom-table-rows">rows</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>tr</code> elements of the table.</p>
<dd>
<dt><var title="">tr</var> = <var title="">table</var> . <code title="dom-table-insertRow">insertRow</code>(<var title="">index</var>)</dt>
<dd>
<p>Creates a <code>tr</code> element, along with a <code>tbody</code> if required, inserts them into the table at the position given by the argument, and returns the <code>tr</code>.</p>
<p>The position is relative to the rows in the table. The index −1 is equivalent to inserting at the end of the table.</p>
<p>If the given position is less than −1 or greater than the number of rows, throws an <code>INDEX_SIZE_ERR</code> exception.</p>
<dd>
<dt><var title="">table</var> . <code title="dom-table-deleteRow">deleteRow</code>(<var title="">index</var>)</dt>
<dd>
<p>Removes the <code>tr</code> element with the given position in the table.</p>
<p>The position is relative to the rows in the table. The index −1 is equivalent to deleting the last row of the table.</p>
<p>If the given position is less than −1 or greater than the index of the last row, or if there are no rows, throws an <code>INDEX_SIZE_ERR</code> exception.</p>
<dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-table-caption"><code>caption</code></dfn> IDL
attribute must return, on getting, the first <code>caption</code>
element child of the <code>table</code> element, if any, or null
otherwise. On setting, if the new value is a <code>caption</code>
element, the first <code>caption</code> element child of the
<code>table</code> element, if any, must be removed, and the new
value must be inserted as the first node of the <code>table</code>
element. If the new value is not a <code>caption</code> element,
then a <code>HIERARCHY_REQUEST_ERR</code> DOM exception must be
raised instead.</p>
<p>The <dfn
title="dom-table-createCaption"><code>createCaption()</code></dfn>
method must return the first <code>caption</code> element child of
the <code>table</code> element, if any; otherwise a new
<code>caption</code> element must be created, inserted as the first
node of the <code>table</code> element, and then returned.</p>
<p>The <dfn
title="dom-table-deleteCaption"><code>deleteCaption()</code></dfn>
method must remove the first <code>caption</code> element child of
the <code>table</code> element, if any.</p>
<p>The <dfn title="dom-table-tHead"><code>tHead</code></dfn> IDL
attribute must return, on getting, the first <code>thead</code>
element child of the <code>table</code> element, if any, or null
otherwise. On setting, if the new value is a <code>thead</code>
element, the first <code>thead</code> element child of the
<code>table</code> element, if any, must be removed, and the new
value must be inserted immediately before the first element in the
<code>table</code> element that is neither a <code>caption</code>
element nor a <code>colgroup</code> element, if any, or at the end
of the table if there are no such elements. If the new value is not
a <code>thead</code> element, then a
<code>HIERARCHY_REQUEST_ERR</code> DOM exception must be raised
instead.</p>
<p>The <dfn
title="dom-table-createTHead"><code>createTHead()</code></dfn>
method must return the first <code>thead</code> element child of the
<code>table</code> element, if any; otherwise a new
<code>thead</code> element must be created and inserted immediately
before the first element in the <code>table</code> element that is
neither a <code>caption</code> element nor a <code>colgroup</code>
element, if any, or at the end of the table if there are no such
elements, and then that new element must be returned.</p>
<p>The <dfn
title="dom-table-deleteTHead"><code>deleteTHead()</code></dfn>
method must remove the first <code>thead</code> element child of the
<code>table</code> element, if any.</p>
<p>The <dfn title="dom-table-tFoot"><code>tFoot</code></dfn> IDL
attribute must return, on getting, the first <code>tfoot</code>
element child of the <code>table</code> element, if any, or null
otherwise. On setting, if the new value is a <code>tfoot</code>
element, the first <code>tfoot</code> element child of the
<code>table</code> element, if any, must be removed, and the new
value must be inserted immediately before the first element in the
<code>table</code> element that is neither a <code>caption</code>
element, a <code>colgroup</code> element, nor a <code>thead</code>
element, if any, or at the end of the table if there are no such
elements. If the new value is not a <code>tfoot</code> element, then
a <code>HIERARCHY_REQUEST_ERR</code> DOM exception must be raised
instead.</p>
<p>The <dfn
title="dom-table-createTFoot"><code>createTFoot()</code></dfn>
method must return the first <code>tfoot</code> element child of the
<code>table</code> element, if any; otherwise a new
<code>tfoot</code> element must be created and inserted immediately
before the first element in the <code>table</code> element that is
neither a <code>caption</code> element, a <code>colgroup</code>
element, nor a <code>thead</code> element, if any, or at the end of
the table if there are no such elements, and then that new element
must be returned.</p>
<p>The <dfn
title="dom-table-deleteTFoot"><code>deleteTFoot()</code></dfn>
method must remove the first <code>tfoot</code> element child of the
<code>table</code> element, if any.</p>
<p>The <dfn title="dom-table-tBodies"><code>tBodies</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>table</code> node, whose filter matches only
<code>tbody</code> elements that are children of the
<code>table</code> element.</p>
<p>The <dfn
title="dom-table-createTBody"><code>createTBody()</code></dfn>
method must create a new <code>tbody</code> element, insert it
immediately after the last <code>tbody</code> element in the
<code>table</code> element, if any, or at the end of the
<code>table</code> element if the <code>table</code> element has no
<code>tbody</code> element children, and then must return the new
<code>tbody</code> element.</p>
<p>The <dfn title="dom-table-rows"><code>rows</code></dfn> attribute
must return an <code>HTMLCollection</code> rooted at the
<code>table</code> node, whose filter matches only <code>tr</code>
elements that are either children of the <code>table</code> element,
or children of <code>thead</code>, <code>tbody</code>, or
<code>tfoot</code> elements that are themselves children of the
<code>table</code> element. The elements in the collection must be
ordered such that those elements whose parent is a
<code>thead</code> are included first, in tree order, followed by
those elements whose parent is either a <code>table</code> or
<code>tbody</code> element, again in tree order, followed finally by
those elements whose parent is a <code>tfoot</code> element, still
in tree order.</p>
<p>The behavior of the <dfn
title="dom-table-insertRow"><code>insertRow(<var
title="">index</var>)</code></dfn> method depends on the state of
the table. When it is called, the method must act as required by the
first item in the following list of conditions that describes the
state of the table and the <var title="">index</var> argument:</p>
<dl class="switch">
<dt>If <var title="">index</var> is less than −1 or greater than
the number of elements in <code title="dom-table-rows">rows</code>
collection:</dt>
<dd>The method must raise an <code>INDEX_SIZE_ERR</code>
exception.</dd>
<dt>If the <code title="dom-table-rows">rows</code> collection has
zero elements in it, and the <code>table</code> has no
<code>tbody</code> elements in it:</dt>
<dd>The method must create a <code>tbody</code> element, then
create a <code>tr</code> element, then append the <code>tr</code>
element to the <code>tbody</code> element, then append the
<code>tbody</code> element to the <code>table</code> element, and
finally return the <code>tr</code> element.</dd>
<dt>If the <code title="dom-table-rows">rows</code> collection has
zero elements in it:</dt>
<dd>The method must create a <code>tr</code> element, append it to
the last <code>tbody</code> element in the table, and return the
<code>tr</code> element.</dd>
<dt>If <var title="">index</var> is missing, equal to −1, or
equal to the number of items in <code
title="dom-table-rows">rows</code> collection:</dt>
<dd>The method must create a <code>tr</code> element, and append it
to the parent of the last <code>tr</code> element in the <code
title="dom-table-rows">rows</code> collection. Then, the newly
created <code>tr</code> element must be returned.</dd>
<dt>Otherwise:</dt>
<dd>The method must create a <code>tr</code> element, insert it
immediately before the <var title="">index</var>th <code>tr</code>
element in the <code title="dom-table-rows">rows</code> collection,
in the same parent, and finally must return the newly created
<code>tr</code> element.</dd>
</dl>
<p>When the <dfn title="dom-table-deleteRow"><code>deleteRow(<var
title="">index</var>)</code></dfn> method is called, the user agent
must run the following steps:</p>
<ol>
<li><p>If <var title="">index</var> is equal to −1, then
<var title="">index</var> must be set to the number if items in the
<code title="dom-table-rows">rows</code> collection, minus
one.</p></li>
<li><p>Now, if <var title="">index</var> is less than zero, or
greater than or equal to the number of elements in the <code
title="dom-table-rows">rows</code> collection, the method must
instead raise an <code>INDEX_SIZE_ERR</code> exception, and these
steps must be aborted.</p></li>
<li><p>Otherwise, the method must remove the <var
title="">index</var>th element in the <code
title="dom-table-rows">rows</code> collection from its parent.</p>
</ol>
<p>The <dfn title="dom-table-summary"><code>summary</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name.</p>
</div>
<h4>The <dfn><code>caption</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As the first element child of a <code>table</code> element.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>, but with no descendant <code>table</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTableCaptionElement</dfn> : <span>HTMLElement</span> {};</pre>
</dd>
</dl>
<p>The <code>caption</code> element <span>represents</span> the title of the
<code>table</code> that is its parent, if it has a parent and that
is a <code>table</code> element.</p>
<div class="impl">
<p>The <code>caption</code> element takes part in the <span>table
model</span>.</p>
</div>
<p>When a <code>table</code> element is the only content in a
<code>figure</code> element's <code>dd</code>, the
<code>caption</code> element should be omitted in favor of the
<code>dt</code>.</p>
<p>A caption can introduce context for a table, making it
significantly easier to understand.</p>
<div class="example">
<p>Consider, for instance, the following table:</p>
<table class="dice-example">
<tr> <th> <th> 1 <th> 2 <th> 3 <th> 4 <th> 5 <th> 6
<tr> <th> 1 <td> 2 <td> 3 <td> 4 <td> 5 <td> 6 <td> 7
<tr> <th> 2 <td> 3 <td> 4 <td> 5 <td> 6 <td> 7 <td> 8
<tr> <th> 3 <td> 4 <td> 5 <td> 6 <td> 7 <td> 8 <td> 9
<tr> <th> 4 <td> 5 <td> 6 <td> 7 <td> 8 <td> 9 <td> 10
<tr> <th> 5 <td> 6 <td> 7 <td> 8 <td> 9 <td> 10 <td> 11
<tr> <th> 6 <td> 7 <td> 8 <td> 9 <td> 10 <td> 11 <td> 12
</table>
<p>In the abstract, this table is not clear. However, with a
caption giving the table's number (for reference in the main prose)
and explaining its use, it makes more sense:</p>
<pre><caption>
<p>Table 1.
<p>This table shows the total score obtained from rolling two
six-sided dice. The first row represents the value of the first die,
the first column the value of the second die. The total is given in
the cell that corresponds to the values of the two dice.
</caption></pre>
<p>This provides the user with more context:</p>
<table class="dice-example">
<caption>
<p>Table 1.
<p>This table shows the total score obtained from rolling two
six-sided dice. The first row represents the value of the first
die, the first column the value of the second die. The total is
given in the cell that corresponds to the values of the two dice.
</caption>
<tr> <th> <th> 1 <th> 2 <th> 3 <th> 4 <th> 5 <th> 6
<tr> <th> 1 <td> 2 <td> 3 <td> 4 <td> 5 <td> 6 <td> 7
<tr> <th> 2 <td> 3 <td> 4 <td> 5 <td> 6 <td> 7 <td> 8
<tr> <th> 3 <td> 4 <td> 5 <td> 6 <td> 7 <td> 8 <td> 9
<tr> <th> 4 <td> 5 <td> 6 <td> 7 <td> 8 <td> 9 <td> 10
<tr> <th> 5 <td> 6 <td> 7 <td> 8 <td> 9 <td> 10 <td> 11
<tr> <th> 6 <td> 7 <td> 8 <td> 9 <td> 10 <td> 11 <td> 12
</table>
</div>
<h4>The <dfn><code>colgroup</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>table</code> element, after any
<code>caption</code> elements and before any <code>thead</code>,
<code>tbody</code>, <code>tfoot</code>, and <code>tr</code>
elements.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>col</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-colgroup-span">span</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTableColElement</dfn> : <span>HTMLElement</span> {
attribute unsigned long <span title="dom-colgroup-span">span</span>;
};</pre>
</dd>
</dl>
<p>The <code>colgroup</code> element <span>represents</span> a <span
title="concept-column-group">group</span> of one or more <span
title="concept-column">columns</span> in the <code>table</code> that
is its parent, if it has a parent and that is a <code>table</code>
element.</p>
<p>If the <code>colgroup</code> element contains no <code>col</code>
elements, then the element may have a <dfn
title="attr-colgroup-span"><code>span</code></dfn> content attribute
specified, whose value must be a <span>valid non-negative
integer</span> greater than zero.</p>
<div class="impl">
<p>The <code>colgroup</code> element and its <code
title="attr-colgroup-span">span</code> attribute take part in the
<span>table model</span>.</p>
<p>The <dfn title="dom-colgroup-span"><code>span</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name. The value must be <span>limited to only non-negative
numbers greater than zero</span>.</p>
</div>
<h4>The <dfn><code>col</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>colgroup</code> element that doesn't have
a <code title="attr-col-span">span</code> attribute.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-col-span">span</code></dd>
<!-- v2: char, to specify the decimal character used in numeric data cells in the column (not header cells) -->
<dt>DOM interface:</dt>
<dd>
<p><code>HTMLTableColElement</code>, same as for
<code>colgroup</code> elements. This interface defines one member,
<code title="dom-col-span">span</code>.</p>
</dd>
</dl>
<p>If a <code>col</code> element has a parent and that is a
<code>colgroup</code> element that itself has a parent that is a
<code>table</code> element, then the <code>col</code> element
<span>represents</span> one or more <span
title="concept-column">columns</span> in the <span
title="concept-column-group">column group</span> represented by that
<code>colgroup</code>.</p>
<p>The element may have a <dfn
title="attr-col-span"><code>span</code></dfn> content attribute
specified, whose value must be a <span>valid non-negative
integer</span> greater than zero.</p>
<div class="impl">
<p>The <code>col</code> element and its <code
title="attr-col-span">span</code> attribute take part in the
<span>table model</span>.</p>
<p>The <dfn title="dom-col-span"><code>span</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name. The value must be <span>limited to only non-negative
numbers greater than zero</span>.</p>
</div>
<h4>The <dfn><code>tbody</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>table</code> element, after any
<code>caption</code>, <code>colgroup</code>, and
<code>thead</code> elements, but only if there are no
<code>tr</code> elements that are children of the
<code>table</code> element.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>tr</code> elements</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTableSectionElement</dfn> : <span>HTMLElement</span> {
readonly attribute <span>HTMLCollection</span> <span title="dom-tbody-rows">rows</span>;
<span>HTMLElement</span> <span title="dom-tbody-insertRow">insertRow</span>(in optional long index);
void <span title="dom-tbody-deleteRow">deleteRow</span>(in long index);
};</pre>
<p>The <code>HTMLTableSectionElement</code> interface is also
used for <code>thead</code> and <code>tfoot</code> elements.</p>
</dd>
</dl>
<p>The <code>tbody</code> element <span>represents</span> a <span
title="concept-row-group">block</span> of <span
title="concept-row">rows</span> that consist of a body of data for
the parent <code>table</code> element, if the <code>tbody</code>
element has a parent and it is a <code>table</code>.</p>
<div class="impl">
<p>The <code>tbody</code> element takes part in the <span>table
model</span>.</p>
</div>
<dl class="domintro">
<dt><var title="">tbody</var> . <code title="dom-tbody-rows">rows</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>tr</code> elements of the table section.</p>
<dd>
<dt><var title="">tr</var> = <var title="">tbody</var> . <code title="dom-tbody-insertRow">insertRow</code>( [ <var title="">index</var> ] )</dt>
<dd>
<p>Creates a <code>tr</code> element, inserts it into the table section at the position given by the argument, and returns the <code>tr</code>.</p>
<p>The position is relative to the rows in the table section. The index −1, which is the default if the argument is omitted, is equivalent to inserting at the end of the table section.</p>
<p>If the given position is less than −1 or greater than the number of rows, throws an <code>INDEX_SIZE_ERR</code> exception.</p>
<dd>
<dt><var title="">tbody</var> . <code title="dom-tbody-deleteRow">deleteRow</code>(<var title="">index</var>)</dt>
<dd>
<p>Removes the <code>tr</code> element with the given position in the table section.</p>
<p>The position is relative to the rows in the table section. The index −1 is equivalent to deleting the last row of the table section.</p>
<p>If the given position is less than −1 or greater than the index of the last row, or if there are no rows, throws an <code>INDEX_SIZE_ERR</code> exception.</p>
<dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-tbody-rows"><code>rows</code></dfn> attribute
must return an <code>HTMLCollection</code> rooted at the element,
whose filter matches only <code>tr</code> elements that are children
of the element.</p>
<p>The <dfn title="dom-tbody-insertRow"><code>insertRow(<var
title="">index</var>)</code></dfn> method must, when invoked on an
element <var title="">table section</var>, act as follows:</p>
<p>If <var title="">index</var> is less than −1 or greater than the
number of elements in the <code title="dom-tbody-rows">rows</code>
collection, the method must raise an <code>INDEX_SIZE_ERR</code>
exception.</p>
<p>If <var title="">index</var> is missing, equal to −1, or
equal to the number of items in the <code
title="dom-tbody-rows">rows</code> collection, the method must
create a <code>tr</code> element, append it to the element <var
title="">table section</var>, and return the newly created
<code>tr</code> element.</p>
<p>Otherwise, the method must create a <code>tr</code> element,
insert it as a child of the <var title="">table section</var>
element, immediately before the <var title="">index</var>th
<code>tr</code> element in the <code
title="dom-tbody-rows">rows</code> collection, and finally must
return the newly created <code>tr</code> element.</p>
<p>The <dfn title="dom-tbody-deleteRow"><code>deleteRow(<var
title="">index</var>)</code></dfn> method must remove the <var
title="">index</var>th element in the <code
title="dom-tbody-rows">rows</code> collection from its parent. If
<var title="">index</var> is less than zero or greater than or equal
to the number of elements in the <code
title="dom-tbody-rows">rows</code> collection, the method must
instead raise an <code>INDEX_SIZE_ERR</code> exception.</p>
</div>
<h4>The <dfn><code>thead</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>table</code> element, after any
<code>caption</code>, and <code>colgroup</code>
elements and before any <code>tbody</code>, <code>tfoot</code>, and
<code>tr</code> elements, but only if there are no other
<code>thead</code> elements that are children of the
<code>table</code> element.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>tr</code> elements</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd><code>HTMLTableSectionElement</code>, as defined for
<code>tbody</code> elements.</dd>
</dl>
<p>The <code>thead</code> element <span>represents</span> the <span
title="concept-row-group">block</span> of <span
title="concept-row">rows</span> that consist of the column labels
(headers) for the parent <code>table</code> element, if the
<code>thead</code> element has a parent and it is a
<code>table</code>.</p>
<div class="impl">
<p>The <code>thead</code> element takes part in the <span>table
model</span>.</p>
</div>
<h4>The <dfn><code>tfoot</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>table</code> element, after any
<code>caption</code>, <code>colgroup</code>, and <code>thead</code>
elements and before any <code>tbody</code> and <code>tr</code>
elements, but only if there are no other <code>tfoot</code>
elements that are children of the <code>table</code> element.</dd>
<dd>As a child of a <code>table</code> element, after any
<code>caption</code>, <code>colgroup</code>, <code>thead</code>,
<code>tbody</code>, and <code>tr</code> elements, but only if there
are no other <code>tfoot</code> elements that are children of the
<code>table</code> element.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>tr</code> elements</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd><code>HTMLTableSectionElement</code>, as defined for
<code>tbody</code> elements.</dd>
</dl>
<p>The <code>tfoot</code> element <span>represents</span> the <span
title="concept-row-group">block</span> of <span
title="concept-row">rows</span> that consist of the column summaries
(footers) for the parent <code>table</code> element, if the
<code>tfoot</code> element has a parent and it is a
<code>table</code>.</p>
<div class="impl">
<p>The <code>tfoot</code> element takes part in the <span>table
model</span>.</p>
</div>
<h4>The <dfn><code>tr</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>thead</code> element.</dd>
<dd>As a child of a <code>tbody</code> element.</dd>
<dd>As a child of a <code>tfoot</code> element.</dd>
<dd>As a child of a <code>table</code> element, after any
<code>caption</code>, <code>colgroup</code>, and <code>thead</code>
elements, but only if there are no <code>tbody</code> elements that
are children of the <code>table</code> element.</dd>
<dt>Content model:</dt>
<dd>When the parent node is a <code>thead</code> element: Zero or more <code>th</code> elements</dd>
<dd>Otherwise: Zero or more <code>td</code> or <code>th</code> elements</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTableRowElement</dfn> : <span>HTMLElement</span> {
readonly attribute long <span title="dom-tr-rowIndex">rowIndex</span>;
readonly attribute long <span title="dom-tr-sectionRowIndex">sectionRowIndex</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-tr-cells">cells</span>;
<span>HTMLElement</span> <span title="dom-tr-insertCell">insertCell</span>(in optional long index);
void <span title="dom-tr-deleteCell">deleteCell</span>(in long index);
};</pre>
</dd>
</dl>
<p>The <code>tr</code> element <span>represents</span> a <span
title="concept-row">row</span> of <span
title="concept-cell">cells</span> in a <span
title="concept-table">table</span>.</p>
<div class="impl">
<p>The <code>tr</code> element takes part in the <span>table
model</span>.</p>
</div>
<dl class="domintro">
<dt><var title="">tr</var> . <code title="dom-tr-rowIndex">rowIndex</code></dt>
<dd>
<p>Returns the position of the row in the table's <code
title="dom-table-rows">rows</code> list.</p>
<p>Returns −1 if the element isn't in a table.</p>
</dd>
<dt><var title="">tr</var> . <code title="dom-tr-sectionRowIndex">sectionRowIndex</code></dt>
<dd>
<p>Returns the position of the row in the table section's <code
title="dom-tbody-rows">rows</code> list.</p>
<p>Returns −1 if the element isn't in a table section.</p>
</dd>
<dt><var title="">tr</var> . <code title="dom-tr-cells">cells</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>td</code> and <code>th</code> elements of the row.</p>
<dd>
<dt><var title="">cell</var> = <var title="">tr</var> . <code title="dom-tr-insertCell">insertCell</code>( [ <var title="">index</var> ] )</dt>
<dd>
<p>Creates a <code>td</code> element, inserts it into the table
row at the position given by the argument, and returns the
<code>td</code>.</p>
<p>The position is relative to the cells in the row. The
index −1, which is the default if the argument is omitted,
is equivalent to inserting at the end of the row.</p>
<p>If the given position is less than −1 or greater than
the number of cells, throws an <code>INDEX_SIZE_ERR</code>
exception.</p>
</dd>
<dt><var title="">tr</var> . <code title="dom-tr-deleteCell">deleteCell</code>(<var title="">index</var>)</dt>
<dd>
<p>Removes the <code>td</code> or <code>th</code> element with the
given position in the row.</p>
<p>The position is relative to the cells in the row. The index
−1 is equivalent to deleting the last cell of the row.</p>
<p>If the given position is less than −1 or greater than
the index of the last cell, or if there are no cells, throws an
<code>INDEX_SIZE_ERR</code> exception.</p>
<dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-tr-rowIndex"><code>rowIndex</code></dfn>
attribute must, if the element has a parent <code>table</code>
element, or a parent <code>tbody</code>, <code>thead</code>, or
<code>tfoot</code> element and a <em>grandparent</em>
<code>table</code> element, return the index of the <code>tr</code>
element in that <code>table</code> element's <code
title="dom-table-rows">rows</code> collection. If there is no such
<code>table</code> element, then the attribute must return
−1.</p>
<p>The <dfn
title="dom-tr-sectionRowIndex"><code>sectionRowIndex</code></dfn>
attribute must, if the element has a parent <code>table</code>,
<code>tbody</code>, <code>thead</code>, or <code>tfoot</code>
element, return the index of the <code>tr</code> element in the
parent element's <code title="">rows</code> collection (for tables,
that's the <code title="dom-table-rows">rows</code> collection; for
table sections, that's the <code title="dom-tbody-rows">rows</code>
collection). If there is no such parent element, then the attribute
must return −1.</p>
<p>The <dfn title="dom-tr-cells"><code>cells</code></dfn> attribute
must return an <code>HTMLCollection</code> rooted at the
<code>tr</code> element, whose filter matches only <code>td</code>
and <code>th</code> elements that are children of the
<code>tr</code> element.</p>
<p>The <dfn title="dom-tr-insertCell"><code>insertCell(<var
title="">index</var>)</code></dfn> method must act as follows:</p>
<p>If <var title="">index</var> is less than −1 or greater than the
number of elements in the <code title="dom-tr-cells">cells</code>
collection, the method must raise an <code>INDEX_SIZE_ERR</code>
exception.</p>
<p>If <var title="">index</var> is missing, equal to −1, or
equal to the number of items in <code
title="dom-tr-cells">cells</code> collection, the method must create
a <code>td</code> element, append it to the <code>tr</code> element,
and return the newly created <code>td</code> element.</p>
<p>Otherwise, the method must create a <code>td</code> element,
insert it as a child of the <code>tr</code> element, immediately
before the <var title="">index</var>th <code>td</code> or
<code>th</code> element in the <code
title="dom-tr-cells">cells</code> collection, and finally must
return the newly created <code>td</code> element.</p>
<p>The <dfn title="dom-tr-deleteCell"><code>deleteCell(<var
title="">index</var>)</code></dfn> method must remove the <var
title="">index</var>th element in the <code
title="dom-tr-cells">cells</code> collection from its parent. If
<var title="">index</var> is less than zero or greater than or equal
to the number of elements in the <code
title="dom-tr-cells">cells</code> collection, the method must
instead raise an <code>INDEX_SIZE_ERR</code> exception.</p>
</div>
<h4>The <dfn><code>td</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Sectioning root</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>tr</code> element.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-tdth-colspan">colspan</code></dd>
<dd><code title="attr-tdth-rowspan">rowspan</code></dd>
<dd><code title="attr-tdth-headers">headers</code></dd>
<!-- v2 char, to specify the decimal character used in numeric cells -->
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTableDataCellElement</dfn> : <span>HTMLTableCellElement</span> {};</pre>
</dd>
</dl>
<p>The <code>td</code> element <span>represents</span> a data <span
title="concept-cell">cell</span> in a table.</p>
<div class="impl">
<p>The <code>td</code> element and its <code
title="attr-tdth-colspan">colspan</code>, <code
title="attr-tdth-rowspan">rowspan</code>, and <code
title="attr-tdth-headers">headers</code> attributes take part in the
<span>table model</span>.</p>
</div>
<h4>The <dfn><code>th</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>tr</code> element.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-tdth-colspan">colspan</code></dd>
<dd><code title="attr-tdth-rowspan">rowspan</code></dd>
<dd><code title="attr-tdth-headers">headers</code></dd>
<dd><code title="attr-th-scope">scope</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTableHeaderCellElement</dfn> : <span>HTMLTableCellElement</span> {
attribute DOMString <span title="dom-th-scope">scope</span>;
};</pre>
</dd>
</dl>
<p>The <code>th</code> element <span>represents</span> a header <span
title="concept-cell">cell</span> in a table.</p>
<p>The <code>th</code> element may have a <dfn
title="attr-th-scope"><code>scope</code></dfn> content attribute
specified. The <code title="attr-th-scope">scope</code> attribute is
an <span>enumerated attribute</span> with five states, four of which
have explicit keywords:</p>
<dl>
<dt>The <dfn title="attr-th-scope-row"><code>row</code></dfn>
keyword, which maps to the <i>row</i> state</dt>
<dd>The <i>row</i> state means the header cell applies to some of
the subsequent cells in the same row(s).</dd>
<dt>The <dfn title="attr-th-scope-col"><code>col</code></dfn>
keyword, which maps to the <i>column</i> state</dt>
<dd>The <i>column</i> state means the header cell applies to some
of the subsequent cells in the same column(s).</dd>
<dt>The <dfn
title="attr-th-scope-rowgroup"><code>rowgroup</code></dfn> keyword,
which maps to the <i>row group</i> state</dt>
<dd>The <i>row group</i> state means the header cell applies to all
the remaining cells in the row group. A <code>th</code> element's
<code title="attr-th-scope">scope</code> attribute must not be in
the <span title="attr-th-scope-rowgroup">row group</span> state if
the element is not anchored in a <span
title="concept-row-group">row group</span>.</dd>
<dt>The <dfn
title="attr-th-scope-colgroup"><code>colgroup</code></dfn> keyword,
which maps to the <i>column group</i> state</dt>
<dd>The <i>column group</i> state means the header cell applies to
all the remaining cells in the column group. A <code>th</code>
element's <code title="attr-th-scope">scope</code> attribute must
not be in the <span title="attr-th-scope-colgroup">column
group</span> state if the element is not anchored in a <span
title="concept-column-group">column group</span>.</dd>
<dt>The <dfn title="attr-th-scope-auto">auto</dfn> state</dt>
<dd>The <i>auto</i> state makes the header cell apply to a set of
cells selected based on context.</dd>
</dl>
<p>The <code title="attr-th-scope">scope</code> attribute's
<i>missing value default</i> is the <i>auto</i> state.</p>
<div class="impl">
<p>The <code>th</code> element and its <code
title="attr-tdth-colspan">colspan</code>, <code
title="attr-tdth-rowspan">rowspan</code>, <code
title="attr-tdth-headers">headers</code>, and <code
title="attr-th-scope">scope</code> attributes take part in the
<span>table model</span>.</p>
<p>The <dfn title="dom-th-scope"><code>scope</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name.</p>
</div>
<div class="example">
<p>The following example shows how the <code
title="attr-th-scope">scope</code> attribute's <code
title="attr-th-scope-rowgroup">rowgroup</code> value affects which
data cells a header cell applies to.</p>
<p>Here is a markup fragment showing a table:</p>
<pre><table>
<thead>
<tr> <th> ID <th> Measurement <th> Average <th> Maximum
<tbody>
<tr> <td> <th scope=rowgroup> Cats <td> <td>
<tr> <td> 93 <th> Legs <td> 3.5 <td> 4
<tr> <td> 10 <th> Tails <td> 1 <td> 1
<tbody>
<tr> <td> <th scope=rowgroup> English speakers <td> <td>
<tr> <td> 32 <th> Legs <td> 2.67 <td> 4
<tr> <td> 35 <th> Tails <td> 0.33 <td> 1
</table></pre>
<p>This would result in the following table:</p>
<table>
<thead>
<tr> <th> ID <th> Measurement <th> Average <th> Maximum
<tbody>
<tr> <td> <th scope=rowgroup> Cats <td> <td>
<tr> <td> 93 <th> Legs <td> 3.5 <td> 4
<tr> <td> 10 <th> Tails <td> 1 <td> 1
<tbody>
<tr> <td> <th scope=rowgroup> English speakers <td> <td>
<tr> <td> 32 <th> Legs <td> 2.67 <td> 4
<tr> <td> 35 <th> Tails <td> 0.33 <td> 1
</table>
<p>The headers in the first row all apply directly down to the rows
in their column.</p>
<p>The headers with the explicit <code
title="attr-th-scope">scope</code> attributes apply to all the
cells in their row group other than the cells in the first column.</p>
<p>The remaining headers apply just to the cells to the right of
them.</p>
<!-- image source: http://software.hixie.ch/utilities/js/live-dom-viewer/saved/151 -->
<img src="images/table-scope-diagram.png" alt=""><!-- (alt is empty because the diagram is completely described by the previous paragraphs) -->
</div>
<h4>Attributes common to <code>td</code> and <code>th</code> elements</h4>
<p>The <code>td</code> and <code>th</code> elements may have a <dfn
title="attr-tdth-colspan"><code>colspan</code></dfn> content
attribute specified, whose value must be a <span>valid non-negative
integer</span> greater than zero.</p>
<p>The <code>td</code> and <code>th</code> elements may also have a
<dfn title="attr-tdth-rowspan"><code>rowspan</code></dfn> content
attribute specified, whose value must be a <span>valid non-negative
integer</span>.</p>
<p>These attributes give the number of columns and rows respectively
that the cell is to span. These attributes must not be used to
overlap cells<span class="impl">, as described in the description of
the <span>table model</span></span>.</p> <!-- conformance criteria
for determining when this is violated are given in the processing
model -->
<hr>
<p>The <code>td</code> and <code>th</code> element may have a <dfn
title="attr-tdth-headers"><code>headers</code></dfn> content
attribute specified. The <code
title="attr-tdth-headers">headers</code> attribute, if specified,
must contain a string consisting of an <span>unordered set of unique
space-separated tokens</span>, each of which must have the value of
an ID of a <code>th</code> element taking part in the same <span
title="concept-table">table</span> as the <code>td</code> or
<code>th</code> element<span class="impl"> (as defined by the
<span>table model</span>)</span>.</p>
<p>A <code>th</code> element with ID <var title="">id</var> is said
to be <i>directly targeted</i> by all <code>td</code> and
<code>th</code> elements in the same <span
title="concept-table">table</span> that have <code
title="attr-tdth-headers">headers</code> attributes whose values
include as one of their tokens the ID <var title="">id</var>. A
<code>th</code> element <var title="">A</var> is said to be
<i>targeted</i> by a <code>th</code> or <code>td</code> element
<var title="">B</var> if either <var title="">A</var> is <i>directly
targeted</i> by <var title="">B</var> or if there exists an element
<var title="">C</var> that is itself <i>targeted</i> by the element
<var title="">B</var> and <var title="">A</var> is <i>directly
targeted</i> by <var title="">C</var>.</p>
<p>A <code>th</code> element must not be <i>targeted</i> by
itself.</p>
<div class="impl">
<p>The <code title="attr-tdth-colspan">colspan</code>, <code
title="attr-tdth-rowspan">rowspan</code>, and <code
title="attr-tdth-headers">headers</code> attributes take part in the
<span>table model</span>.</p>
</div>
<hr>
<p>The <code>td</code> and <code>th</code> elements implement
interfaces that inherit from the <code>HTMLTableCellElement</code>
interface:</p>
<pre class="idl">interface <dfn>HTMLTableCellElement</dfn> : <span>HTMLElement</span> {
attribute unsigned long <span title="dom-tdth-colSpan">colSpan</span>;
attribute unsigned long <span title="dom-tdth-rowSpan">rowSpan</span>;
attribute DOMString <span title="dom-tdth-headers">headers</span>;
readonly attribute long <span title="dom-tdth-cellIndex">cellIndex</span>;
};</pre>
<dl class="domintro">
<dt><var title="">cell</var> . <code title="dom-tdth-cellIndex">cellIndex</code></dt>
<dd>
<p>Returns the position of the cell in the row's <code
title="dom-tr-cells">cells</code> list.</p>
<p>Returns 0 if the element isn't in a row.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-tdth-colSpan"><code>colSpan</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name. The value must be <span>limited to only non-negative
numbers greater than zero</span>.</p>
<p>The <dfn title="dom-tdth-rowSpan"><code>rowSpan</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name. Its default value, which must be used if <span
title="rules for parsing non-negative integers">parsing the
attribute as a non-negative integer</span> returns an error, is 1.</p>
<p>The <dfn title="dom-tdth-headers"><code>headers</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name.</p>
<p>The <dfn title="dom-tdth-cellIndex"><code>cellIndex</code></dfn>
IDL attribute must, if the element has a parent <code>tr</code>
element, return the index of the cell's element in the parent
element's <code title="dom-tr-cells">cells</code> collection. If
there is no such parent element, then the attribute must return
0.</p>
</div>
<div class="impl">
<h4>Processing model</h4>
<p>The various table elements and their content attributes together
define the <dfn>table model</dfn>.</p>
<p>A <dfn title="concept-table">table</dfn> consists of cells
aligned on a two-dimensional grid of <dfn
title="concept-slots">slots</dfn> with coordinates (<var
title="">x</var>, <var title="">y</var>). The grid is finite, and is
either empty or has one or more slots. If the grid has one or more
slots, then the <var title="">x</var> coordinates are always in the
range <span title="">0 ≤ <var
title="">x</var> < <var title="">x<sub
title="">width</sub></var></span>, and the <var title="">y</var>
coordinates are always in the range <span title="">0 ≤ <var
title="">y</var> < <var title="">y<sub
title="">height</sub></var></span>. If one or both of <var
title="">x<sub title="">width</sub></var> and <var title="">y<sub
title="">height</sub></var> are zero, then the table is empty (has
no slots). Tables correspond to <code>table</code> elements.</p>
<p>A <dfn title="concept-cell">cell</dfn> is a set of slots anchored
at a slot (<var title="">cell<sub title="">x</sub></var>, <var
title="">cell<sub title="">y</sub></var>), and with a particular
<var title="">width</var> and <var title="">height</var> such that
the cell covers all the slots with coordinates (<var
title="">x</var>, <var title="">y</var>) where <span title=""><var
title="">cell<sub title="">x</sub></var> ≤ <var
title="">x</var> < <var title="">cell<sub
title="">x</sub></var>+<var title="">width</var></span> and
<span title=""><var title="">cell<sub
title="">y</sub></var> ≤ <var
title="">y</var> < <var title="">cell<sub
title="">y</sub></var>+<var title="">height</var></span>. Cells can
either be <em>data cells</em> or <em>header cells</em>. Data cells
correspond to <code>td</code> elements, and header cells correspond
to <code>th</code> elements. Cells of both types can have zero or
more associated header cells.</p>
<p>It is possible, in certain error cases, for two cells to occupy
the same slot.</p>
<p>A <dfn title="concept-row">row</dfn> is a complete set of slots
from <span title=""><var title="">x</var>=0</span> to <span title=""><var
title="">x</var>=<var title="">x<sub
title="">width</sub></var>-1</span>, for a particular value of <var
title="">y</var>. Rows correspond to <code>tr</code> elements.</p>
<p>A <dfn title="concept-column">column</dfn> is a complete set of
slots from <span title=""><var title="">y</var>=0</span> to <span title=""><var
title="">y</var>=<var title="">y<sub
title="">height</sub></var>-1</span>, for a particular value of <var
title="">x</var>. Columns can correspond to <code>col</code>
elements, but in the absence of <code>col</code> elements are
implied.</p>
<p>A <dfn title="concept-row-group">row group</dfn> is a set of
<span title="concept-row">rows</span> anchored at a slot (0, <var
title="">group<sub title="">y</sub></var>) with a particular <var
title="">height</var> such that the row group covers all the slots
with coordinates (<var title="">x</var>, <var title="">y</var>)
where <span title="">0 ≤ <var
title="">x</var> < <var title="">x<sub
title="">width</sub></var></span> and <span title=""><var
title="">group<sub title="">y</sub></var> ≤ <var
title="">y</var> < <var title="">group<sub
title="">y</sub></var>+<var title="">height</var></span>. Row groups
correspond to <code>tbody</code>, <code>thead</code>, and
<code>tfoot</code> elements. Not every row is necessarily in a row
group.</p>
<p>A <dfn title="concept-column-group">column group</dfn> is a set
of <span title="concept-column">columns</span> anchored at a slot
(<var title="">group<sub title="">x</sub></var>, 0) with a
particular <var title="">width</var> such that the column group
covers all the slots with coordinates (<var title="">x</var>, <var
title="">y</var>) where <span title=""><var title="">group<sub
title="">x</sub></var> ≤ <var
title="">x</var> < <var title="">group<sub
title="">x</sub></var>+<var title="">width</var></span> and
<span title="">0 ≤ <var title="">y</var> < <var
title="">y<sub title="">height</sub></var></span>. Column groups
correspond to <code>colgroup</code> elements. Not every column is
necessarily in a column group.</p>
<p><span title="concept-row-group">Row groups</span> cannot overlap
each other. Similarly, <span title="concept-column-group">column
groups</span> cannot overlap each other.</p>
<p>A <span title="concept-cell">cell</span> cannot cover slots that
are from two or more <span title="concept-row-group">row
groups</span>. It is, however, possible for a cell to be in multiple
<span title="concept-column-group">column groups</span>. All the
slots that form part of one cell are part of zero or one <span
title="concept-row-group">row groups</span> and zero or more <span
title="concept-column-group">column groups</span>.</p>
<p>In addition to <span title="concept-cell">cells</span>, <span
title="concept-column">columns</span>, <span
title="concept-row">rows</span>, <span title="concept-row-group">row
groups</span>, and <span title="concept-column-group">column
groups</span>, <span title="concept-table">tables</span> can have a
<code>caption</code> element associated with them. This gives the
table a heading, or legend.</p>
<p>A <dfn>table model error</dfn> is an error with the data
represented by <code>table</code> elements and their
descendants. Documents must not have table model errors.</p>
<h5>Forming a table</h5>
<p>To determine which elements correspond to which slots in a <span
title="concept-table">table</span> associated with a
<code>table</code> element, to determine the dimensions of the table
(<var title="">x<sub title="">width</sub></var> and <var
title="">y<sub title="">height</sub></var>), and to determine if
there are any <span title="table model error">table model
errors</span>, user agents must use the following algorithm:</p>
<ol>
<li>
<p>Let <var title="">x<sub title="">width</sub></var> be zero.</p>
</li>
<li>
<p>Let <var title="">y<sub title="">height</sub></var> be zero.</p>
</li>
<li>
<p>Let <var title="">pending <code>tfoot</code> elements</var> be
a list of <code>tfoot</code> elements, initially empty.</p>
</li>
<li>
<p>Let <var title="">the table</var> be the <span
title="concept-table">table</span> represented by the
<code>table</code> element. The <var title="">x<sub
title="">width</sub></var> and <var title="">y<sub
title="">height</sub></var> variables give <var title="">the
table</var>'s dimensions. <var title="">The table</var> is
initially empty.</p>
</li>
<li>
<!-- this step is here just so that we can be sure to have a first
element in the next step, so that we can set up the "advance"
exception-handling thingy below; otherwise it'd be more
complicated. it's not a perf optimization per se. -->
<p>If the <code>table</code> element has no children elements,
then return <var title="">the table</var> (which will be empty),
and abort these steps.</p>
</li>
<li>
<p>Associate the first <code>caption</code> element child of the
<code>table</code> element with <var title="">the table</var>. If
there are no such children, then it has no associated
<code>caption</code> element.</p>
</li>
<li>
<p>Let the <var title="">current element</var> be the first
element child of the <code>table</code> element.</p>
<p>If a step in this algorithm ever requires the <var
title="">current element</var> to be <dfn
title="concept-table-advance">advanced to the next child of the
<code>table</code></dfn> when there is no such next child, then
the user agent must jump to the step labeled <i>end</i>, near the
end of this algorithm.</p>
</li>
<li>
<p>While the <var title="">current element</var> is not one of the
following elements, <span
title="concept-table-advance">advance</span> the <var
title="">current element</var> to the next child of the
<code>table</code>:</p>
<ul class="brief">
<li><code>colgroup</code></li>
<li><code>thead</code></li>
<li><code>tbody</code></li>
<li><code>tfoot</code></li>
<li><code>tr</code></li>
</ul>
</li>
<li>
<p>If the <var title="">current element</var> is a
<code>colgroup</code>, follow these substeps:</p>
<ol>
<li>
<p><i>Column groups</i>: Process the <var title="">current
element</var> according to the appropriate case below:</p>
<dl class="switch">
<dt>If the <var title="">current element</var> has any
<code>col</code> element children</dt>
<dd>
<p>Follow these steps:</p>
<ol>
<li>
<p>Let <var title="">x<sub title="">start</sub></var> have
the value of <span title=""><var title="">x<sub
title="">width</sub></var></span>.</p>
</li>
<li>
<p>Let the <var title="">current column</var> be the first
<code>col</code> element child of the <code>colgroup</code>
element.</p>
</li>
<li>
<p><i>Columns</i>: If the <var title="">current column</var>
<code>col</code> element has a <code
title="attr-col-span">span</code> attribute, then parse its
value using the <span>rules for parsing non-negative
integers</span>.</p>
<p>If the result of parsing the value is not an error or
zero, then let <var title="">span</var> be that value.</p>
<p>Otherwise, if the <code>col</code> element has no <code
title="attr-col-span">span</code> attribute, or if trying to
parse the attribute's value resulted in an error, then let
<var title="">span</var> be 1.</p>
</li>
<li>
<p>Increase <var title="">x<sub title="">width</sub></var> by
<var title="">span</var>.</p>
</li>
<li>
<p>Let the last <var title="">span</var> <span
title="concept-column">columns</span> in <var title="">the
table</var> correspond to the <var title="">current
column</var> <code>col</code> element.</p>
</li>
<li>
<p>If <var title="">current column</var> is not the last
<code>col</code> element child of the <code>colgroup</code>
element, then let the <var title="">current column</var> be
the next <code>col</code> element child of the
<code>colgroup</code> element, and return to the step
labeled <i>columns</i>.</p>
</li>
<li>
<p>Let all the last <span
title="concept-column">columns</span> in <var title="">the
table</var> from <span title="">x=<var title="">x<sub
title="">start</sub></var></span> to <span title="">x=<var
title="">x<sub title="">width</sub></var>-1</span> form a
new <span title="concept-column-group">column group</span>,
anchored at the slot (<var title="">x<sub
title="">start</sub></var>, 0), with width <span title=""><var
title="">x<sub title="">width</sub></var>-<var
title="">x<sub title="">start</sub></var></span>,
corresponding to the <code>colgroup</code> element.</p>
</li>
</ol>
</dd>
<dt>If the <var title="">current element</var> has no
<code>col</code> element children</dt>
<dd>
<ol>
<li>
<p>If the <code>colgroup</code> element has a <code
title="attr-colgroup-span">span</code> attribute, then parse
its value using the <span>rules for parsing non-negative
integers</span>.</p>
<p>If the result of parsing the value is not an error or
zero, then let <var title="">span</var> be that value.</p>
<p>Otherwise, if the <code>colgroup</code> element has no
<code title="attr-colgroup-span">span</code> attribute, or if
trying to parse the attribute's value resulted in an error,
then let <var title="">span</var> be 1.</p>
</li>
<li>
<p>Increase <var title="">x<sub title="">width</sub></var> by
<var title="">span</var>.</p>
</li>
<li>
<p>Let the last <var title="">span</var> <span
title="concept-column">columns</span> in <var title="">the
table</var> form a new <span
title="concept-column-group">column group</span>, anchored
at the slot (<span title=""><var title="">x<sub
title="">width</sub></var>-<var title="">span</var></span>,
0), with width <var title="">span</var>, corresponding to
the <code>colgroup</code> element.</p>
</li>
</ol>
</dd>
</dl>
</li>
<li>
<p><span title="concept-table-advance">Advance</span> the <var
title="">current element</var> to the next child of the
<code>table</code>.</p>
</li>
<li>
<p>While the <var title="">current element</var> is not one of
the following elements, <span
title="concept-table-advance">advance</span> the <var
title="">current element</var> to the next child of the
<code>table</code>:</p>
<ul class="brief">
<li><code>colgroup</code></li>
<li><code>thead</code></li>
<li><code>tbody</code></li>
<li><code>tfoot</code></li>
<li><code>tr</code></li>
</ul>
</li>
<li>
<p>If the <var title="">current element</var> is a
<code>colgroup</code> element, jump to the step labeled
<i>column groups</i> above.</p>
</li>
</ol>
</li>
<li>
<p>Let <var title="">y<sub title="">current</sub></var> be
zero.</p>
</li>
<li>
<p>Let the <var title="">list of downward-growing cells</var> be
an empty list.</p>
</li>
<li>
<p><i>Rows</i>: While the <var title="">current element</var> is
not one of the following elements, <span
title="concept-table-advance">advance</span> the <var
title="">current element</var> to the next child of the
<code>table</code>:</p>
<ul class="brief">
<li><code>thead</code></li>
<li><code>tbody</code></li>
<li><code>tfoot</code></li>
<li><code>tr</code></li>
</ul>
</li>
<li>
<p>If the <var title="">current element</var> is a
<code>tr</code>, then run the <span>algorithm for processing
rows</span>, <span title="concept-table-advance">advance</span>
the <var title="">current element</var> to the next child of the
<code>table</code>, and return to the step labeled
<i>rows</i>.</p>
</li>
<li>
<p>Run the <span>algorithm for ending a row group</span>.</p>
</li>
<li>
<p>If the <var title="">current element</var> is a
<code>tfoot</code>, then add that element to the list of <var
title="">pending <code>tfoot</code> elements</var>, <span
title="concept-table-advance">advance</span> the <var
title="">current element</var> to the next child of the
<code>table</code>, and return to the step labeled
<i>rows</i>.</p>
</li>
<li>
<p>The <var title="">current element</var> is either a
<code>thead</code> or a <code>tbody</code>.</p>
<p>Run the <span>algorithm for processing row groups</span>.</p>
</li>
<li>
<p><span title="concept-table-advance">Advance</span> the <var
title="">current element</var> to the next child of the
<code>table</code>.</p>
</li>
<li>
<p>Return to the step labeled <i>rows</i>.</p>
</li>
<li>
<p><i>End</i>: For each <code>tfoot</code> element in the list of
<var title="">pending <code>tfoot</code> elements</var>, in tree
order, run the <span>algorithm for processing row
groups</span>.</p>
</li>
<li>
<p>If there exists a <span title="concept-row">row</span> or <span
title="concept-column">column</span> in the <span
title="concept-table">table</span> <var title="">the table</var>
containing only <span title="concept-slots">slots</span> that do
not have a <span title="concept-cell">cell</span> anchored to
them, then this is a <span>table model error</span>.</p>
</li>
<li>
<p>Return <var title="">the table</var>.</p>
</li>
</ol>
<p>The <dfn>algorithm for processing row groups</dfn>, which is
invoked by the set of steps above for processing
<code>thead</code>, <code>tbody</code>, and <code>tfoot</code>
elements, is:</p>
<ol>
<li>
<p>Let <var title="">y<sub title="">start</sub></var> have the
value of <var title="">y<sub title="">height</sub></var>.</p>
</li>
<li>
<p>For each <code>tr</code> element that is a child of the element
being processed, in tree order, run the <span>algorithm for
processing rows</span>.</p>
</li>
<li>
<!-- if we added any rows, make them part of a row group -->
<p>If <span title=""><var title="">y<sub
title="">height</sub></var> > <var title="">y<sub
title="">start</sub></var></span>, then let all the last <span
title="concept-row">rows</span> in <var title="">the table</var>
from <span title="">y=<var title="">y<sub title="">start</sub></var></span>
to <span title="">y=<var title="">y<sub
title="">height</sub></var>-1</span> form a new <span
title="concept-row-group">row group</span>, anchored at the slot
with coordinate (0, <var title="">y<sub
title="">start</sub></var>), with height <span title=""><var title="">y<sub
title="">height</sub></var>-<var title="">y<sub
title="">start</sub></var></span>, corresponding to the element
being processed.</p>
</li>
<li>
<p>Run the <span>algorithm for ending a row group</span>.</p>
</li>
</ol>
<p>The <dfn>algorithm for ending a row group</dfn>, which is invoked
by the set of steps above when starting and ending a block of rows,
is:</p>
<ol>
<li>
<p>While <var title="">y<sub title="">current</sub></var> is less
than <var title="">y<sub title="">height</sub></var>, follow these
steps:</p>
<ol>
<li>
<p>Run the <span>algorithm for growing downward-growing
cells</span>.</p>
</li>
<li>
<p>Increase <var title="">y<sub title="">current</sub></var> by
1.</p>
</li>
</ol>
</li>
<li>
<p>Empty the <var title="">list of downward-growing
cells</var>.</p>
</li>
</ol>
<p>The <dfn>algorithm for processing rows</dfn>, which is invoked by
the set of steps above for processing <code>tr</code> elements,
is:</p>
<ol>
<li>
<p>If <var title="">y<sub title="">height</sub></var> is equal to
<var title="">y<sub title="">current</sub></var>, then increase
<var title="">y<sub title="">height</sub></var> by 1. (<var
title="">y<sub title="">current</sub></var> is never
<em>greater</em> than <var title="">y<sub
title="">height</sub></var>.)</p>
</li>
<li>
<p>Let <var title="">x<sub title="">current</sub></var> be 0.</p>
</li>
<li>
<p>Run the <span>algorithm for growing downward-growing
cells</span>.</p>
</li>
<li>
<p>If the <code>tr</code> element being processed has no
<code>td</code> or <code>th</code> element children, then increase
<var title="">y<sub title="">current</sub></var> by 1, abort this
set of steps, and return to the algorithm above.</p>
</li>
<li>
<p>Let <var title="">current cell</var> be the first
<code>td</code> or <code>th</code> element in the <code>tr</code>
element being processed.</p>
</li>
<li>
<p><i>Cells</i>: While <var title="">x<sub
title="">current</sub></var> is less than <var title="">x<sub
title="">width</sub></var> and the slot with coordinate (<var
title="">x<sub title="">current</sub></var>, <var title="">y<sub
title="">current</sub></var>) already has a cell assigned to it,
increase <var title="">x<sub title="">current</sub></var> by
1.</p>
</li>
<li>
<p>If <var title="">x<sub title="">current</sub></var> is equal to
<var title="">x<sub title="">width</sub></var>, increase <var
title="">x<sub title="">width</sub></var> by 1. (<var
title="">x<sub title="">current</sub></var> is never
<em>greater</em> than <var title="">x<sub
title="">width</sub></var>.)</p>
</li>
<li>
<p>If the <var title="">current cell</var> has a <code
title="attr-tdth-colspan">colspan</code> attribute, then <span
title="rules for parsing non-negative integers">parse that
attribute's value</span>, and let <var title="">colspan</var> be
the result.</p>
<p>If parsing that value failed, or returned zero, or if the
attribute is absent, then let <var title="">colspan</var> be 1,
instead.</p>
</li>
<li>
<p>If the <var title="">current cell</var> has a <code
title="attr-tdth-rowspan">rowspan</code> attribute, then <span title="rules for
parsing non-negative integers">parse that attribute's
value</span>, and let <var title="">rowspan</var> be the
result.</p>
<p>If parsing that value failed or if the attribute is absent,
then let <var title="">rowspan</var> be 1, instead.</p>
</li>
<li>
<p>If <var title="">rowspan</var> is zero, then let <var
title="">cell grows downward</var> be true, and set <var
title="">rowspan</var> to 1. Otherwise, let <var title="">cell
grows downward</var> be false.</p>
</li>
<li>
<p>If <span title=""><var title="">x<sub
title="">width</sub></var> < <var title="">x<sub
title="">current</sub></var>+<var title="">colspan</var></span>,
then let <var title="">x<sub title="">width</sub></var> be
<span title=""><var title="">x<sub title="">current</sub></var>+<var
title="">colspan</var></span>.</p>
</li>
<li>
<p>If <span title=""><var title="">y<sub
title="">height</sub></var> < <var title="">y<sub
title="">current</sub></var>+<var title="">rowspan</var></span>,
then let <var title="">y<sub title="">height</sub></var> be
<span title=""><var title="">y<sub title="">current</sub></var>+<var
title="">rowspan</var></span>.</p>
</li>
<li>
<p>Let the slots with coordinates (<var title="">x</var>, <var
title="">y</var>) such that <span title=""><var title="">x<sub
title="">current</sub></var> ≤ <var
title="">x</var> < <var title="">x<sub
title="">current</sub></var>+<var title="">colspan</var></span>
and <span title=""><var title="">y<sub
title="">current</sub></var> ≤ <var
title="">y</var> < <var title="">y<sub
title="">current</sub></var>+<var title="">rowspan</var></span> be
covered by a new <span title="concept-cell">cell</span> <var
title="">c</var>, anchored at (<var title="">x<sub
title="">current</sub></var>, <var title="">y<sub
title="">current</sub></var>), which has width <var
title="">colspan</var> and height <var title="">rowspan</var>,
corresponding to the <var title="">current cell</var> element.</p>
<p>If the <var title="">current cell</var> element is a
<code>th</code> element, let this new cell <var title="">c</var>
be a header cell; otherwise, let it be a data cell.</p>
<p>To establish which header cells apply to the <var
title="">current cell</var> element, use the <span>algorithm for
assigning header cells</span> described in the next section.</p>
<p>If any of the slots involved already had a <span
title="concept-cell">cell</span> covering them, then this is a
<span>table model error</span>. Those slots now have two cells
overlapping.</p>
</li>
<li>
<p>If <var title="">cell grows downward</var> is true, then add
the tuple {<var title="">c</var>, <var title="">x<sub
title="">current</sub></var>, <var title="">colspan</var>} to the
<var title="">list of downward-growing cells</var>.</p>
</li>
<li>
<p>Increase <var title="">x<sub title="">current</sub></var> by
<var title="">colspan</var>.</p>
</li>
<li>
<p>If <var title="">current cell</var> is the last <code>td</code>
or <code>th</code> element in the <code>tr</code> element being
processed, then increase <var title="">y<sub
title="">current</sub></var> by 1, abort this set of steps, and
return to the algorithm above.</p>
</li>
<li>
<p>Let <var title="">current cell</var> be the next
<code>td</code> or <code>th</code> element in the <code>tr</code>
element being processed.</p>
</li>
<li>
<p>Return to the step labelled <i>cells</i>.</p>
</li>
</ol>
<p>When the algorithms above require the user agent to run the
<dfn>algorithm for growing downward-growing cells</dfn>, the user
agent must, for each {<var title="">cell</var>, <var
title="">cell<sub title="">x</sub></var>, <var title="">width</var>}
tuple in the <var title="">list of downward-growing cells</var>, if
any, extend the <span title="concept-cell">cell</span> <var
title="">cell</var> so that it also covers the slots with
coordinates (<var title="">x</var>, <var title="">y<sub
title="">current</sub></var>), where <span title=""><var title="">cell<sub
title="">x</sub></var> ≤ <var
title="">x</var> < <var title="">cell<sub
title="">x</sub></var>+<var title="">width</var></span>.</p>
<h5 id="header-and-data-cell-semantics">Forming relationships between data cells and header cells</h5>
<p>Each cell can be assigned zero or more header cells. The
<dfn>algorithm for assigning header cells</dfn> to a cell <var
title="">principal cell</var> is as follows.</p>
<ol>
<!-- INITIALIZATION -->
<li>
<p>Let <var title="">header list</var> be an empty list of
cells.</p>
</li>
<li>
<p>Let (<var title="">principal<sub title="">x</sub></var>, <var
title="">principal<sub title="">y</sub></var>) be the coordinate
of the slot to which the <var title="">principal cell</var> is
anchored.</p>
</li>
<li>
<dl class="switch">
<dt>If the <var title="">principal cell</var> has a <code
title="attr-tdth-headers">headers</code> attribute specified</dt>
<dd>
<!-- HEADERS="" -->
<ol>
<li>
<p>Take the value of the <var title="">principal cell</var>'s
<code title="attr-tdth-headers">headers</code> attribute and
<span title="split a string on spaces">split it on
spaces</span>, letting <var title="">id list</var> be the list
of tokens obtained.</p>
</li>
<li>
<!-- support headers="" to <td> for legacy compat -->
<!-- note that it's not conforming though -->
<p>For each token in the <var title="">id list</var>, if the
first element in the <code>Document</code> with an ID equal to
the token is a cell in the same <span
title="concept-table">table</span>, and that cell is not the
<var title="">principal cell</var>, then add that cell to <var
title="">header list</var>.</p>
</li>
</ol>
</dd>
<dt>If <var title="">principal cell</var> does not have a <code
title="attr-tdth-headers">headers</code> attribute specified</dt>
<dd>
<ol>
<li>
<p>Let <var title="">principal<sub title="">width</sub></var>
be the width of the <var title="">principal cell</var>.</p>
</li>
<li>
<p>Let <var title="">principal<sub title="">height</sub></var>
be the height of the <var title="">principal cell</var>.</p>
</li>
<!-- HORIZONTAL -->
<li>
<p>For each value of <var title="">y</var> from <var
title="">principal<sub title="">y</sub></var> to <span title=""><var
title="">principal<sub title="">y</sub></var>+<var
title="">principal<sub title="">height</sub></var>-1</span>,
run the <span>internal algorithm for scanning and assigning
header cells</span>, with the <var title="">principal
cell</var>, the <var title="">header list</var>, the initial
coordinate (<var title="">principal<sub
title="">x</sub></var>,<var title="">y</var>), and the
increments <span title="">Δ<var title="">x</var>=−1</span>
and <span title="">Δ<var title="">y</var>=0</span>.</p>
</li>
<!-- VERTICAL -->
<li>
<p>For each value of <var title="">x</var> from <var
title="">principal<sub title="">x</sub></var> to <span title=""><var
title="">principal<sub title="">x</sub></var>+<var
title="">principal<sub title="">width</sub></var>-1</span>,
run the <span>internal algorithm for scanning and assigning
header cells</span>, with the <var title="">principal
cell</var>, the <var title="">header list</var>, the initial
coordinate (<var title="">x</var>,<var title="">principal<sub
title="">y</sub></var>), and the increments <span title="">Δ<var
title="">x</var>=0</span> and <span title="">Δ<var
title="">y</var>=−1</span>.</p>
</li>
<!-- ROW GROUP HEADERS -->
<li>
<p>If the <var title="">principal cell</var> is anchored in a
<span title="concept-row-group">row group</span>, then add all
header cells that are <span title="row group header">row group
headers</span> and are anchored in the same row group with an
<var title="">x</var>-coordinate less than or equal to
<span title=""><var title="">principal<sub title="">x</sub></var>+<var
title="">principal<sub title="">width</sub></var>-1</span> and
a <var title="">y</var>-coordinate less than or equal to
<span title=""><var title="">principal<sub title="">y</sub></var>+<var
title="">principal<sub title="">height</sub></var>-1</span> to
<var title="">header list</var>.</p>
</li>
<!-- COLUMN GROUP HEADERS -->
<li>
<p>If the <var title="">principal cell</var> is anchored in a
<span title="concept-column-group">column group</span>, then
add all header cells that are <span title="column group
header">column group headers</span> and are anchored in the
same column group with an <var title="">x</var>-coordinate
less than or equal to <span title=""><var title="">principal<sub
title="">x</sub></var>+<var title="">principal<sub
title="">width</sub></var>-1</span> and a <var
title="">y</var>-coordinate less than or equal to <span title=""><var
title="">principal<sub title="">y</sub></var>+<var
title="">principal<sub title="">height</sub></var>-1</span> to
<var title="">header list</var>.</p>
</li>
</ol>
</dd>
</dl>
</li>
<!-- CLEANUP -->
<li>
<p>Remove all the <span title="empty cell">empty cells</span> from
the <var title="">header list</var>.</p>
</li>
<li>
<p>Remove any duplicates from the <var title="">header
list</var>.</p>
</li>
<li>
<p>Assign the headers in the <var title="">header list</var> to
the <var title="">principal cell</var>.</p>
</li>
</ol>
<p>The <dfn>internal algorithm for scanning and assigning header
cells</dfn>, given a <var title="">principal cell</var>, a <var
title="">header list</var>, an initial coordinate (<var
title="">initial<sub title="">x</sub></var>, <var
title="">initial<sub title="">y</sub></var>), and Δ<var
title="">x</var> and Δ<var title="">y</var> increments, is as
follows:</p>
<ol>
<li>
<p>Let <var title="">x</var> equal <var title="">initial<sub
title="">x</sub></var>.</p>
</li>
<li>
<p>Let <var title="">y</var> equal <var title="">initial<sub
title="">y</sub></var>.</p>
</li>
<li>
<p>Let <var title="">opaque headers</var> be an empty list of
cells.</p>
</li>
<li>
<dl class="switch">
<dt>If <var title="">principal cell</var> is a header cell</dt>
<dd><p>Let <var title="">in header block</var> be true, and let
<var title="">headers from current header block</var> be a list
of cells containing just the <var title="">principal
cell</var>.</p></dd>
<dt>Otherwise</dt>
<dd><p>Let <var title="">in header block</var> be false and let
<var title="">headers from current header block</var> be an
empty list of cells.</p>
</dl>
</li>
<li>
<p><i>Loop</i>: Increment <var title="">x</var> by Δ<var
title="">x</var>; increment <var title="">y</var> by Δ<var
title="">y</var>.</p>
<p class="note">For each invocation of this algorithm, one of
Δ<var title="">x</var> and Δ<var title="">y</var> will
be −1, and the other will be 0.</p>
</li>
<li>
<p>If either <var title="">x</var> or <var title="">y</var> is
less than 0, then abort this internal algorithm.</p>
</li>
<li>
<p>If there is no cell covering slot (<var title="">x</var>,
<var title="">y</var>), or if there is more than one cell
covering slot (<var title="">x</var>, <var title="">y</var>),
return to the substep marked <i>loop</i>.</p>
</li>
<li>
<p>Let <var title="">current cell</var> be the cell covering
slot (<var title="">x</var>, <var title="">y</var>).</p>
</li>
<li>
<dl class="switch">
<dt>If <var title="">current cell</var> is a header cell</dt>
<dd>
<ol>
<li><p>Set <var title="">in header block</var> to
true.</p></li>
<li><p>Add <var title="">current cell</var> to <var
title="">headers from current header block</var>.</p></li>
<li><p>Let <var title="">blocked</var> be false.</p></li>
<li>
<dl class="switch">
<dt>If Δ<var title="">x</var> is 0</dt>
<dd>
<p>If there are any cells in the <var title="">opaque
headers</var> list anchored with the same <var
title="">x</var>-coordinate as the <var title="">current
cell</var>, and with the same width as <var title="">current
cell</var>, then let <var title="">blocked</var> be
true.</p>
<p>If the <var title="">current cell</var> is not a
<span>column header</span>, then let <var
title="">blocked</var> be true.</p>
</dd>
<dt>If Δ<var title="">y</var> is 0</dt>
<dd>
<p>If there is are any cells in the <var title="">opaque
headers</var> list anchored with the same <var
title="">y</var>-coordinate as the <var title="">current
cell</var>, and with the same height as <var
title="">current cell</var>, then let <var
title="">blocked</var> be true.</p>
<p>If the <var title="">current cell</var> is not a
<span>row header</span>, then let <var
title="">blocked</var> be true.</p>
</dd>
</dl>
</li>
<li><p>If <var title="">blocked</var> is false, then add the
<var title="">current cell</var> to the <var title="">headers
list</var>.</p></li>
</ol>
</dd>
<dt>If <var title="">current cell</var> is a data cell and <var title="">in header block</var> is true</dt>
<dd><p>Set <var title="">in header block</var> to false. Add
all the cells in <var title="">headers from current header
block</var> to the <var title="">opaque headers</var> list, and
empty the <var title="">headers from current header block</var>
list.</p>
</dl>
</li>
<li>
<p>Return to the step marked <i>loop</i>.</p>
</li>
</ol>
<p>A header cell anchored at the slot with coordinate (<var
title="">x</var>, <var title="">y</var>) with width <var
title="">width</var> and height <var title="">height</var> is said
to be a <dfn>column header</dfn> if any of the following conditions
are true:</p>
<ul>
<li>The cell's <code title="attr-th-scope">scope</code> attribute
is in the <span title="attr-th-scope-col">column</span> state, or</li>
<li>The cell's <code title="attr-th-scope">scope</code> attribute
is in the <span title="attr-th-scope-auto">auto</span> state, and
there are no data cells in any of the cells covering slots with
<var title="">y</var>-coordinates <var title="">y</var>
.. <span title=""><var title="">y</var>+<var
title="">height</var>-1</span>.</li>
</ul>
<p>A header cell anchored at the slot with coordinate (<var
title="">x</var>, <var title="">y</var>) with width <var
title="">width</var> and height <var title="">height</var> is said
to be a <dfn>row header</dfn> if any of the following conditions
are true:</p>
<ul>
<li>The cell's <code title="attr-th-scope">scope</code> attribute
is in the <span title="attr-th-scope-row">row</span> state, or</li>
<li>The cell's <code title="attr-th-scope">scope</code> attribute
is in the <span title="attr-th-scope-auto">auto</span> state, the
cell is not a <span>column header</span>, and there are no data
cells in any of the cells covering slots with <var
title="">x</var>-coordinates <var title="">x</var> .. <span title=""><var
title="">x</var>+<var title="">width</var>-1</span>.</li>
</ul>
<p>A header cell is said to be a <dfn>column group header</dfn> if
its <code title="attr-th-scope">scope</code> attribute is in the
<span title="attr-th-scope-colgroup">column group</span> state.</p>
<p>A header cell is said to be a <dfn>row group header</dfn> if
its <code title="attr-th-scope">scope</code> attribute is in the
<span title="attr-th-scope-rowgroup">row group</span> state.</p>
<p>A cell is said to be an <dfn>empty cell</dfn> if it contains no
elements and its text content, if any, consists only of
<span>White_Space</span> characters.</p>
</div>
<h4>Examples</h4>
<p><i>This section is non-normative.</i></p>
<p>The following shows how might one mark up the bottom part of
table 45 of the <cite>Smithsonian physical tables, Volume
71</cite>:</p>
<!-- Smithsonian physical tables, Volume 71: By Smithsonian Institution, Frederick Eugene Fowle; page 76 -->
<pre><table>
<caption>Specification values: <b>Steel</b>, <b>Castings</b>,
Ann. A.S.T.M. A27-16, Class B;* P max. 0.06; S max. 0.05.</caption>
<thead>
<tr>
<th rowspan=2>Grade.</th>
<th rowspan=2>Yield Point.</th>
<th colspan=2>Ultimate tensile strength</th>
<th rowspan=2>Per sent elong. 50.8mm or 2 in.</th>
<th rowspan=2>Per cent reduct. area.</th>
</tr>
<tr>
<th>kg/mm<sup>2</sup></th>
<th>lb/in<sup>2</sup></th>
</tr>
</thead>
<tbody>
<tr>
<td>Hard</td>
<td>0.45 ultimate</td>
<td>56.2</td>
<td>80,000</td>
<td>15</td>
<td>20</td>
</tr>
<tr>
<td>Medium</td>
<td>0.45 ultimate</td>
<td>49.2</td>
<td>70,000</td>
<td>18</td>
<td>25</td>
</tr>
<tr>
<td>Soft</td>
<td>0.45 ultimate</td>
<td>42.2</td>
<td>60,000</td>
<td>22</td>
<td>30</td>
</tr>
</tbody>
</table></pre>
<p>This table could look like this:</p>
<table id="table-example-1">
<caption>Specification values: <b>Steel</b>, <b>Castings</b>,
Ann. A.S.T.M. A27-16, Class B;* P max. 0.06; S max. 0.05.</caption>
<thead>
<tr>
<th rowspan=2>Grade.</th>
<th rowspan=2>Yield Point.</th>
<th colspan=2>Ultimate tensile strength</th>
<th rowspan=2>Per cent elong. 50.8 mm or 2 in.</th>
<th rowspan=2>Per cent reduct. area.</th>
</tr>
<tr>
<th>kg/mm<sup>2</sup></th>
<th>lb/in<sup>2</sup></th>
</tr>
</thead>
<tbody>
<tr>
<td>Hard</td>
<td>0.45 ultimate</td>
<td>56.2</td>
<td>80,000</td>
<td>15</td>
<td>20</td>
</tr>
<tr>
<td>Medium</td>
<td>0.45 ultimate</td>
<td>49.2</td>
<td>70,000</td>
<td>18</td>
<td>25</td>
</tr>
<tr>
<td>Soft</td>
<td>0.45 ultimate</td>
<td>42.2</td>
<td>60,000</td>
<td>22</td>
<td>30</td>
</tr>
</tbody>
</table>
<hr>
<p>The following shows how one might mark up the gross margin table
on page 46 of Apple, Inc's 10-K filing for fiscal year 2008:</p>
<pre><table>
<thead>
<tr>
<th>
<th>2008
<th>2007
<th>2006
<tbody>
<tr>
<th>Net sales
<td>$ 32,479
<td>$ 24,006
<td>$ 19,315
<tr>
<th>Cost of sales
<td> 21,334
<td> 15,852
<td> 13,717
<tbody>
<tr>
<th>Gross margin
<td>$ 11,145
<td>$ 8,154
<td>$ 5,598
<tfoot>
<tr>
<th>Gross margin percentage
<td>34.3%
<td>34.0%
<td>29.0%
</table></pre>
<p>This table could look like this:</p>
<table class="apple-table-examples e1">
<thead>
<tr>
<th>
<th>2008
<th>2007
<th>2006
<tbody>
<tr>
<th>Net sales
<td>$ 32,479
<td>$ 24,006
<td>$ 19,315
<tr>
<th>Cost of sales
<td> 21,334
<td> 15,852
<td> 13,717
<tbody>
<tr>
<th>Gross margin
<td>$ 11,145
<td>$ 8,154
<td>$ 5,598
<tfoot>
<tr>
<th>Gross margin percentage
<td>34.3%
<td>34.0%
<td>29.0%
</table>
<hr>
<p>The following shows how one might mark up the operating expenses
table from lower on the same page of that document:</p>
<pre><table>
<colgroup> <col>
<colgroup> <col> <col> <col>
<thead>
<tr> <th> <th>2008 <th>2007 <th>2006
<tbody>
<tr> <th scope=rowgroup> Research and development
<td> $ 1,109 <td> $ 782 <td> $ 712
<tr> <th scope=row> Percentage of net sales
<td> 3.4% <td> 3.3% <td> 3.7%
<tbody>
<tr> <th scope=rowgroup> Selling, general, and administrative
<td> $ 3,761 <td> $ 2,963 <td> $ 2,433
<tr> <th scope=row> Percentage of net sales
<td> 11.6% <td> 12.3% <td> 12.6%
</table></pre>
<p>This table could look like this:</p>
<table class="apple-table-examples e2">
<thead>
<tr> <th> <th>2008 <th>2007 <th>2006
<tbody>
<tr> <th scope=rowgroup> Research and development
<td> $ 1,109 <td> $ 782 <td> $ 712
<tr> <th scope=row> Percentage of net sales
<td> 3.4% <td> 3.3% <td> 3.7%
<tbody>
<tr> <th scope=rowgroup> Selling, general, and administrative
<td> $ 3,761 <td> $ 2,963 <td> $ 2,433
<tr> <th scope=row> Percentage of net sales
<td> 11.6% <td> 12.3% <td> 12.6%
</table>
<h3 id="forms">Forms</h3>
<p>Forms allow unscripted client-server interaction: given a form, a
user can provide data, submit it to the server, and have the server
act on it accordingly (e.g. returning the results of a search or
calculation). The elements used in forms can also be used for user
interaction with no associated submission mechanism, in conjunction
with scripts.</p>
<p>Mostly for historical reasons, elements in this section fall into
several overlapping (but subtly different) categories in addition to
the usual ones like <span>flow content</span>, <span>phrasing
content</span>, and <span>interactive content</span>.</p>
<p>A number of the elements are <dfn title="form-associated
element">form-associated elements</dfn>, which means they can have a
<span>form owner</span> and, to expose this, have a <code
title="attr-fae-form">form</code> content attribute with a matching
<code title="dom-fae-form">form</code> IDL attribute.</p>
<ul class="brief category-list">
<li><code>button</code></li>
<li><code>fieldset</code></li>
<li><code>input</code></li>
<li><code>keygen</code></li>
<li><code>label</code></li>
<li><code>object</code></li>
<li><code>output</code></li>
<li><code>select</code></li>
<li><code>textarea</code></li>
</ul>
<p>The <span title="form-associated element">form-associated
elements</span> fall into several subcategories:</p>
<dl>
<dt><dfn title="category-listed">Listed</dfn></dt>
<dd>
<p>Denotes elements that are listed in the <code
title="dom-form-elements"><var title="">form</var>.elements</code>
and <code title="dom-fieldset-elements"><var
title="">fieldset</var>.elements</code> APIs.</p>
<ul class="brief category-list">
<li><code>button</code></li>
<li><code>fieldset</code></li>
<li><code>input</code></li>
<li><code>keygen</code></li>
<li><code>object</code></li>
<li><code>output</code></li>
<li><code>select</code></li>
<li><code>textarea</code></li>
</ul>
</dd>
<dt><dfn title="category-label">Labelable</dfn></dt>
<dd>
<p>Denotes elements that can be associated with <code>label</code>
elements.</p>
<ul class="brief category-list">
<li><code>button</code></li>
<li><code>input</code></li>
<li><code>keygen</code></li>
<li><code>select</code></li>
<li><code>textarea</code></li>
</ul>
</dd>
<dt><dfn title="category-submit">Submittable elements</dfn></dt>
<dd>
<p>Denotes elements that can be used for <a
href="#constructing-form-data-set">constructing the form data
set</a> when a <code>form</code> element is <span
title="concept-form-submit">submitted</span>.</p>
<ul class="brief category-list">
<li><code>button</code></li>
<li><code>input</code></li>
<li><code>keygen</code></li>
<li><code>object</code></li>
<li><code>select</code></li>
<li><code>textarea</code></li>
</ul>
</dd>
<dt><dfn title="category-reset">Resettable elements</dfn></dt>
<dd>
<p>Denotes elements that can be affected when a <code>form</code>
element is <span title="concept-form-reset">reset</span>.</p>
<ul class="brief category-list">
<li><code>input</code></li>
<li><code>keygen</code></li>
<li><code>output</code></li>
<li><code>select</code></li>
<li><code>textarea</code></li>
</ul>
</dd>
</dl>
<p>In addition, some <span title="category-submit">submittable
elements</span> can be, depending on their attributes, <dfn
title="concept-button">buttons</dfn>. The prose below defines when
an element is a button. Some buttons are specifically <dfn
title="concept-submit-button">submit buttons</dfn>.</p>
<p class="note">The <code>object</code> element is also a
<span>form-associated element</span> and can, with the use of a
suitable <span>plugin</span>, partake in <span>form
submission</span>.</p>
<h4>The <dfn><code>form</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>, but with no <code>form</code> element descendants.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-form-accept-charset">accept-charset</code></dd>
<dd><code title="attr-fs-action">action</code></dd>
<dd><code title="attr-form-autocomplete">autocomplete</code></dd>
<dd><code title="attr-fs-enctype">enctype</code></dd>
<dd><code title="attr-fs-method">method</code></dd>
<dd><code title="attr-form-name">name</code></dd>
<dd><code title="attr-fs-novalidate">novalidate</code></dd>
<dd><code title="attr-fs-target">target</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">[OverrideBuiltins]
interface <dfn>HTMLFormElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-form-acceptCharset">acceptCharset</span>;
attribute DOMString <span title="dom-fs-action">action</span>;
attribute boolean <span title="dom-form-autocomplete">autocomplete</span>;
attribute DOMString <span title="dom-fs-enctype">enctype</span>;
attribute DOMString <span title="dom-fs-method">method</span>;
attribute DOMString <span title="dom-form-name">name</span>;
attribute boolean <span title="dom-fs-noValidate">noValidate</span>;
attribute DOMString <span title="dom-fs-target">target</span>;
readonly attribute <span>HTMLFormControlsCollection</span> <span title="dom-form-elements">elements</span>;
readonly attribute long <span title="dom-form-length">length</span>;
caller getter any <span title="dom-form-item">item</span>(in unsigned long index);
caller getter any <span title="dom-form-namedItem">namedItem</span>(in DOMString name);
void <span title="dom-form-submit">submit</span>();
void <span title="dom-form-reset">reset</span>();
boolean <span title="dom-form-checkValidity">checkValidity</span>();
void <span title="dom-form-dispatchFormInput">dispatchFormInput</span>();
void <span title="dom-form-dispatchFormChange">dispatchFormChange</span>();
};</pre>
</dd>
</dl>
<p>The <code>form</code> element <span>represents</span> a
collection of <span title="form-associated element">form-associated
elements</span>, some of which can represent editable values that
can be submitted to a server for processing.</p>
<p>The <dfn
title="attr-form-accept-charset"><code>accept-charset</code></dfn>
attribute gives the character encodings that are to be used for the
submission. If specified, the value must be an <span>ordered set of
unique space-separated tokens</span>, and each token must be an
<span>ASCII case-insensitive</span> match for the <span>preferred
MIME name</span> of an <span>ASCII-compatible character
encoding</span>. <a href="#refsIANACHARSET">[IANACHARSET]</a></p>
<p>The <dfn title="attr-form-name"><code>name</code></dfn> attribute
represents the <code>form</code>'s name within the <code
title="dom-document-forms">forms</code> collection. The value must
not be the empty string, and the value must be unique amongst the
<code>form</code> elements in the <code
title="dom-document-forms">forms</code> collection that it is in, if
any.</p>
<p>The <dfn
title="attr-form-autocomplete"><code>autocomplete</code></dfn>
attribute is an <span>enumerated attribute</span>. The attribute has
two states. The <code title="attr-form-autocomplete-on">on</code>
keyword maps to the <dfn
title="attr-form-autocomplete-on-state">on</dfn> state, and the
<code title="attr-form-autocomplete-off">off</code> keyword maps to
the <dfn title="attr-form-autocomplete-off-state">off</dfn>
state. The attribute may also be omitted. The <i>missing value
default</i> is the <span
title="attr-form-autocomplete-on-state">on</span> state. The <span
title="attr-form-autocomplete-off-state">off</span> state indicates
that by default, <code>input</code> elements in the form will have
their <span>resulting autocompletion state</span> set to <i
title="">off</i>; the <span
title="attr-form-autocomplete-on-state">on</span> state indicates
that by default, <code>input</code> elements in the form will have
their <span>resulting autocompletion state</span> set to <i
title="">on</i>.</p>
<p>The <code title="attr-fs-action">action</code>, <code
title="attr-fs-enctype">enctype</code>, <code
title="attr-fs-method">method</code>, <code
title="attr-fs-novalidate">novalidate</code>, and <code
title="attr-fs-target">target</code> attributes are <span>attributes
for form submission</span>.</p>
<dl class="domintro">
<dt><var title="">form</var> . <code title="dom-form-elements">elements</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the form controls in
the form (excluding image buttons for historical reasons).</p>
</dd>
<dt><var title="">form</var> . <code title="dom-form-length">length</code></dt>
<dd>
<p>Returns the number of form controls in the form (excluding
image buttons for historical reasons).</p>
</dd>
<dt><var title="">element</var> = <var title="">form</var> . <code title="dom-form-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">form</var>[<var title="">index</var>]</dt>
<dt><var title="">form</var>(<var title="">index</var>)</dt>
<dd>
<p>Returns the <var title="">index</var>th element in the form
(excluding image buttons for historical reasons).</p>
</dd>
<dt><var title="">element</var> = <var title="">form</var> . <code title="dom-form-namedItem">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">form</var>[<var title="">name</var>]</dt>
<dt><var title="">form</var>(<var title="">name</var>)</dt>
<dd>
<p>Returns the form control in the form with the given ID or <code
title="attr-fe-name">name</code> (excluding image buttons for
historical reasons).</p>
<p>Once an element has been referenced using a particular name,
that name will continue being available as a way to reference that
element in this method, even if the element's actual ID or <code
title="attr-fe-name">name</code> changes, for as long as the
element remains in the <code>Document</code>.</p>
<p>If there are multiple matching items, then a
<code>NodeList</code> object containing all those elements is
returned.</p>
<p>Returns null if no element with that <span
title="concept-id">ID</span> or <code
title="attr-fe-name">name</code> could be found.</p>
</dd>
<dt><var title="">form</var> . <code title="dom-form-submit">submit</code>()</dt>
<dd>
<p>Submits the form.</p>
</dd>
<dt><var title="">form</var> . <code title="dom-form-reset">reset</code>()</dt>
<dd>
<p>Resets the form.</p>
</dd>
<dt><var title="">form</var> . <code title="dom-form-checkValidity">checkValidity</code>()</dt>
<dd>
<p>Returns true if the form's controls are all valid; otherwise,
returns false.</p>
</dd>
<dt><var title="">form</var> . <code title="dom-form-dispatchFormInput">dispatchFormInput</code>()</dt>
<dd>
<p>Dispatches a <code title="event-forminput">forminput</code> event at all the form controls.</p>
</dd>
<dt><var title="">form</var> . <code title="dom-form-dispatchFormChange">dispatchFormChange</code>()</dt>
<dd>
<p>Dispatches a <code title="event-formchange">formchange</code> event at all the form controls.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-form-autocomplete"><code>autocomplete</code></dfn> and
<dfn title="dom-form-name"><code>name</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name.</p>
<p>The <dfn
title="dom-form-acceptCharset"><code>acceptCharset</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-form-accept-charset">accept-charset</code> content
attribute.</p>
<hr>
<p>The <dfn title="dom-form-elements"><code>elements</code></dfn>
IDL attribute must return an <code>HTMLFormControlsCollection</code>
rooted at the <code>Document</code> node, whose filter matches <span
title="category-listed">listed</span> elements whose <span>form
owner</span> is the <code>form</code> element, with the exception of
<code>input</code> elements whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-image">Image Button</span> state, which must,
for historical reasons, be excluded from this particular
collection.</p>
<p>The <dfn title="dom-form-length"><code>length</code></dfn> IDL
attribute must return the number of nodes <span title="represented
by the collection">represented</span> by the <code
title="dom-form-elements">elements</code> collection.</p>
<p>The
<span>indices of the supported indexed properties</span> at any
instant are the indices supported by the object returned by the
<code title="dom-form-elements">elements</code> attribute at that
instant.</p>
<p>The <dfn title="dom-form-item"><code>item(<var
title="">index</var>)</code></dfn> method must return the value
returned by the method of the same name on the <code
title="dom-form-elements">elements</code> collection, when invoked
with the same argument.</p>
<p>Each <code>form</code> element has a mapping of names to elements
called the <dfn>past names map</dfn>. It is used to persist names of
controls even when they change names.</p>
<p>The <span>names of the supported named properties</span> are the
union of the names currently supported by the object returned by the
<code title="dom-form-elements">elements</code> attribute, and the
names currently in the <span>past names map</span>.</p>
<p>The <dfn title="dom-form-namedItem"><code>namedItem(<var
title="">name</var>)</code></dfn> method, when called, must run the
following steps:</p>
<ol>
<li>
<p>If <var title="">name</var> is one of the <span>names of the
supported named properties</span> of the object returned by the
<code title="dom-form-elements">elements</code> attribute, then
run these substeps:</p>
<ol>
<li><p>Let <var title="">candidate</var> be the object returned
by the <code
title="dom-HTMLFormControlsCollection-namedItem">namedItem()</code>
method on the object returned by the <code
title="dom-form-elements">elements</code> attribute when passed
the <var title="">name</var> argument.</p></li>
<li><p>If <var title="">candidate</var> is an element, then add a
mapping from <var title="">name</var> to <var
title="">candidate</var> in the <code>form</code> element's
<span>past names map</span>, replacing the previous entry with
the same name, if any.</p></li>
<li><p>Return <var title="">candidate</var> and abort these
steps.</p></li>
</ol>
</li>
<li><p>Otherwise, <var title="">name</var> is the name of one of
the entries in the <code>form</code> element's <span>past names
map</span>: return the object associated with <var
title="">name</var> in that map.</p></li>
</ol>
<p>If an element listed in the <code>form</code> element's <span>past
names map</span> is removed from the <code>Document</code>, then its
entries must be removed from the map.</p>
<!--
This ridiculous setup is intended to do as much of the right thing
while still supporting code written to work in IE7. IE versions
prior to IE8 do not update the names on the <form> element
collection to match new names when elements are renamed, and there
are enough pages that rename elements and then access them by
their old name that we have to support this.
But we still want to expose them using the new names, so as far as
possible we pretend the legacy names aren't there except if
there's no other element actually named that way.
Removing the element did remove the legacy name in IE7:
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...%3Cform%20action%3D%22%2F%22%3E%3Cinput%20name%3Dsubmit%3E%3C%2Fform%3E%0A%3Cscript%3E%0A%20w(document.forms%5B0%5D.submit)%3B%0A%20w(document.forms%5B0%5D.removeChild(document.getElementsByTagName('input')%5B0%5D))%3B%0A%20w(document.forms%5B0%5D.length)%3B%0A%20try%20%7B%20document.forms%5B0%5D.submit()%3B%20%7D%20catch%20(e)%20%20%7B%20w(e.message)%20%7D%0A%3C%2Fscript%3E
There's no interop on what happens when the name was originally a
duplicate name, so we don't persist such accesses - at the time
of writing, Safari returned the first element, Firefox returned
null (as we do), and IE7 returned the original collection:
http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...%3Cform%20action%3D%22%2F%22%3E%3Cinput%20name%3Da%20id%3Dfirst%3E%3Cinput%20name%3Da%20id%3Dsecond%3E%3C%2Fform%3E%0A%3Cscript%3E%0A%20w%28document.forms[0].a%29%3B%0A%20document.getElementsByTagName%28%27input%27%29[0].name%20%3D%20%27b%27%3B%0A%20document.getElementsByTagName%28%27input%27%29[1].name%20%3D%20%27b%27%3B%0A%20w%28document.forms[0].length%29%3B%0A%20w%28document.forms[0].a.id%29%3B%0A%3C%2Fscript%3E
-->
<hr>
<p>The <dfn title="dom-form-submit"><code>submit()</code></dfn>
method, when invoked, must <span
title="concept-form-submit">submit</span> the <code>form</code>
element from the <code>form</code> element itself, with the <var
title="">scripted-submit</var> flag set.</p>
<p>The <dfn title="dom-form-reset"><code>reset()</code></dfn>
method, when invoked, must run the following steps:</p>
<ol>
<li><p>If the <code>form</code> element is marked as <i>locked for
reset</i>, then abort these steps.</p></li>
<li><p>Mark the <code>form</code> element as <dfn>locked for
reset</dfn>.</p></li>
<li><p><span title="concept-form-reset">Reset</span> the
<code>form</code> element.</p></li>
<li><p>Unmark the <code>form</code> element as <i>locked for
reset</i>.</p></li>
</ol>
<p>If the <dfn
title="dom-form-checkValidity"><code>checkValidity()</code></dfn>
method is invoked, the user agent must <span>statically validate the
constraints</span> of the <code>form</code> element, and return true
if the constraint validation return a <i>positive</i> result, and
false if it returned a <i>negative</i> result.</p>
<p>If the <dfn
title="dom-form-dispatchFormInput"><code>dispatchFormInput()</code></dfn>
method is invoked, the user agent must <span>broadcast <code
title="event-forminput">forminput</code> events</span> from the
<code>form</code> element.</p>
<p>If the <dfn
title="dom-form-dispatchFormChange"><code>dispatchFormChange()</code></dfn>
method is invoked, the user agent must <span>broadcast <code
title="event-formchange">formchange</code> events</span> from the
<code>form</code> element.</p>
</div>
<div class="example">
<p>This example shows two search forms:</p>
<pre><form action="http://www.google.com/search" method="get">
<label>Google: <input type="search" name="q"></label> <input type="submit" value="Search...">
</form>
<form action="http://www.bing.com/search" method="get">
<label>Bing: <input type="search" name="q"></label> <input type="submit" value="Search...">
</form></pre>
</div>
<h4>The <dfn><code>fieldset</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Sectioning root</span>.</dd>
<dd><span title="category-listed">Listed</span> <span>form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Optionally a <code>legend</code> element, followed by <span>flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-fieldset-disabled">disabled</code></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-fe-name">name</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLFieldSetElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-fieldset-disabled">disabled</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
attribute DOMString <span title="dom-fe-name">name</span>;
readonly attribute DOMString <span title="dom-fieldset-type">type</span>;
readonly attribute <span>HTMLFormControlsCollection</span> <span title="dom-fieldset-elements">elements</span>;
readonly attribute boolean <span title="dom-cva-willValidate">willValidate</span>;
readonly attribute <span>ValidityState</span> <span title="dom-cva-validity">validity</span>;
readonly attribute DOMString <span title="dom-cva-validationMessage">validationMessage</span>;
boolean <span title="dom-cva-checkValidatity">checkValidity</span>();
void <span title="dom-cva-setCustomValidity">setCustomValidity</span>(in DOMString error);
};</pre>
</dd>
</dl>
<p>The <code>fieldset</code> element <span>represents</span> a set
of form controls optionally grouped under a common name.</p>
<p>The name of the group is given by the first <code>legend</code>
element that is a child of the <code>fieldset</code> element, if
any. The remainder of the descendants form the group.</p>
<p>The <dfn
title="attr-fieldset-disabled"><code>disabled</code></dfn>
attribute, when specified, causes all the form control descendants
of the <code>fieldset</code> element, excluding those that are
descendants of the <code>fieldset</code> element's first
<code>legend</code> element child, if any, to be <span
title="concept-fe-disabled">disabled</span>.</p>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>fieldset</code> element with its
<span>form owner</span>. The <code title="attr-fe-name">name</code>
attribute represents the element's name.</p>
<dl class="domintro">
<dt><var title="">fieldset</var> . <code title="dom-fieldset-type">type</code></dt>
<dd>
<p>Returns the string "fieldset".</p>
</dd>
<dt><var title="">fieldset</var> . <code title="dom-form-elements">elements</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the form controls in
the element.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-fieldset-disabled"><code>disabled</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name.</p>
<p>The <dfn title="dom-fieldset-type"><code>type</code></dfn> IDL
attribute must return the string "<code
title="">fieldset</code>".</p>
<p>The <dfn
title="dom-fieldset-elements"><code>elements</code></dfn> IDL
attribute must return an <code>HTMLFormControlsCollection</code>
rooted at the <code>fieldset</code> element, whose filter matches
<span title="category-listed">listed</span> elements.</p>
<p>The <code title="dom-cva-willValidate">willValidate</code>,
<code title="dom-cva-validity">validity</code>, and <code
title="dom-cva-validationMessage">validationMessage</code>
attributes, and the <code
title="dom-cva-checkValidatity">checkValidity()</code> and
<code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
methods, are part of the <span>constraint validation API</span>.</p>
<p><strong>Constraint validation</strong>: <code>fieldset</code>
elements are always <span>barred from constraint
validation</span>.</p>
</div>
<div class="example">
<p>The following snippet shows a fieldset with a checkbox in the
legend that controls whether or not the fieldset is enabled. The
contents of the fieldset consist of two required text fields and an
optional year/month control.</p>
<pre><fieldset name="clubfields" disabled>
<legend> <label>
<input type=checkbox name=club onchange="form.clubfields.disabled = !checked">
Use Club Card
</label> </legend>
<p><label>Name on card: <input name=clubname required></label></p>
<p><label>Card number: <input name=clubnum required pattern="[-0-9]+"></label></p>
<p><label>Expiry date: <input name=clubexp type=month></label></p>
</fieldset></pre>
</div>
<h4>The <dfn><code>legend</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As the first child of a <code>fieldset</code> element.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLLegendElement</dfn> : <span>HTMLElement</span> {
readonly attribute <span>HTMLFormElement</span> <span title="dom-legend-form">form</span>;
};</pre>
</dd>
</dl>
<p>The <code>legend</code> element <span>represents</span> a caption
for the rest of the contents of the <code>legend</code> element's
parent <code>fieldset</code> element<span class="impl">, if
any</span>.</p>
<dl class="domintro">
<dt><var title="">legend</var> . <code title="dom-legend-form">form</code></dt>
<dd>
<p>Returns the element's <code>form</code> element, if any, or
null otherwise.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-legend-form"><code>form</code></dfn> IDL
attribute's behavior depends on whether the <code>legend</code>
element is in a <code>fieldset</code> element or not. If the
<code>legend</code> has a <code>fieldset</code> element as its
parent, then the <code title="dom-legend-form">form</code> IDL
attribute must return the same value as the <code
title="dom-fae-form">form</code> IDL attribute on that
<code>fieldset</code> element. Otherwise, it must return null.</p>
</div>
<h4>The <dfn><code>label</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dd><span>Form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>, but with no descendant <span title="category-label">labelable form-associated elements</span> unless it is the element's <span>labeled control</span>, and no descendant <code>label</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-label-for">for</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLLabelElement</dfn> : <span>HTMLElement</span> {
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
attribute DOMString <span title="dom-label-htmlFor">htmlFor</span>;
readonly attribute <span>HTMLElement</span> <span title="dom-label-control">control</span>;
};</pre>
</dd>
</dl>
<p>The <code>label</code> <span>represents</span> a caption in a
user interface. The caption can be associated with a specific form
control<span class="impl">, known as the <code>label</code>
element's <dfn>labeled control</dfn></span>, either using <code
title="attr-label-for">for</code> attribute, or by putting the form
control inside the <code>label</code> element itself.</p>
<div class="impl">
<p>Except where otherwise specified by the following rules, a
<code>label</code> element has no <span>labeled control</span>.</p>
</div>
<p>The <dfn title="attr-label-for"><code>for</code></dfn> attribute
may be specified to indicate a form control with which the caption
is to be associated. If the attribute is specified, the attribute's
value must be the ID of a <span title="category-label">labelable
form-associated element</span> in the same <code>Document</code> as
the <code>label</code> element. <span class="impl">If the attribute
is specified and there is an element in the <code>Document</code>
whose ID is equal to the value of the <code
title="attr-label-for">for</code> attribute, and the first such
element is a <span title="category-label">labelable form-associated
element</span>, then that element is the <code>label</code>
element's <span>labeled control</span>.</span></p>
<div class="impl">
<p>If the <code title="attr-label-for">for</code> attribute is not
specified, but the <code>label</code> element has a <span
title="category-label">labelable form-associated element</span>
descendant, then the first such descendant in <span>tree
order</span> is the <code>label</code> element's <span>labeled
control</span>.</p>
<p>The <code>label</code> element's exact default presentation and
behavior, in particular what its <span>activation behavior</span>
might be, if anything, should match the platform's label
behavior. When the <span>labeled control</span> is not <span>being
rendered</span>, then the <code>label</code> element's
<span>activation behavior</span> must be to do nothing.</p>
<div class="example">
<p>For example, on platforms where clicking a checkbox label checks
the checkbox, clicking the <code>label</code> in the following
snippet could trigger the user agent to <span>run synthetic click
activation steps</span> on the <code>input</code> element, as if
the element itself had been triggered by the user:</p>
<pre><label><input type=checkbox name=lost> Lost</label></pre>
<p>On other platforms, the behavior might be just to focus the
control, or do nothing.</p>
</div>
</div>
<dl class="domintro">
<dt><var title="">label</var> . <code title="dom-label-control">control</code></dt>
<dd>
<p>Returns the form control that is associated with this element.</p>
</dd>
</dl>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>label</code> element with its
<span>form owner</span>.</p>
<div class="impl">
<p>The <dfn title="dom-label-htmlFor"><code>htmlFor</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-label-for">for</code> content attribute.</p>
<p>The <dfn title="dom-label-control"><code>control</code></dfn> IDL
attribute must return the <code>label</code> element's <span>labeled
control</span>, if any, or null if there isn't one.</p>
</div>
<hr>
<dl class="domintro">
<dt><var title="">control</var> . <code title="dom-lfe-labels">labels</code></dt>
<dd>
<p>Returns a <code>NodeList</code> of all the <code>label</code>
elements that the form control is associated with.</p>
</dd>
</dl>
<div class="impl">
<p><span title="category-label">Labelable form-associated
elements</span> have a <code>NodeList</code> object associated with
them that represents the list of <code>label</code> elements, in
<span>tree order</span>, whose <span>labeled control</span> is the
element in question. The <dfn
title="dom-lfe-labels"><code>labels</code></dfn> IDL attribute of
<span title="category-label">labelable form-associated
elements</span>, on getting, must return that <code>NodeList</code>
object.</p>
</div>
<div class="example">
<p>The following example shows three form controls each with a
label, two of which have small text showing the right format for
users to use.</p>
<pre><p><label>Full name: <input name=fn> <small>Format: First Last</small></label></p>
<p><label>Age: <input name=age type=number min=0></label></p>
<p><label>Post code: <input name=pc> <small>Format: AB12 3CD</small></label></p></pre>
</div>
<h4>The <dfn><code>input</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd>If the <code title="attr-input-type">type</code> attribute is <em>not</em> in the <span title="attr-input-type-hidden">Hidden</span> state: <span>Interactive content</span>.</dd>
<dd><span title="category-listed">Listed</span>, <span title="category-label">labelable</span>, <span title="category-submit">submittable</span>, and <span title="category-reset">resettable</span> <span>form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-input-accept">accept</code></dd>
<dd><code title="attr-input-alt">alt</code></dd>
<dd><code title="attr-input-autocomplete">autocomplete</code></dd>
<dd><code title="attr-fe-autofocus">autofocus</code></dd>
<dd><code title="attr-input-checked">checked</code></dd>
<dd><code title="attr-fe-disabled">disabled</code></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-fs-formaction">formaction</code></dd>
<dd><code title="attr-fs-formenctype">formenctype</code></dd>
<dd><code title="attr-fs-formmethod">formmethod</code></dd>
<dd><code title="attr-fs-formnovalidate">formnovalidate</code></dd>
<dd><code title="attr-fs-formtarget">formtarget</code></dd>
<dd><code title="attr-dim-height">height</code></dd>
<dd><code title="attr-input-list">list</code></dd>
<dd><code title="attr-input-max">max</code></dd>
<dd><code title="attr-input-maxlength">maxlength</code></dd>
<dd><code title="attr-input-min">min</code></dd>
<dd><code title="attr-input-multiple">multiple</code></dd>
<dd><code title="attr-fe-name">name</code></dd>
<dd><code title="attr-input-pattern">pattern</code></dd>
<dd><code title="attr-input-placeholder">placeholder</code></dd>
<dd><code title="attr-input-readonly">readonly</code></dd>
<dd><code title="attr-input-required">required</code></dd>
<dd><code title="attr-input-size">size</code></dd>
<dd><code title="attr-input-src">src</code></dd>
<dd><code title="attr-input-step">step</code></dd>
<dd><code title="attr-input-type">type</code></dd>
<dd><code title="attr-input-value">value</code></dd>
<dd><code title="attr-dim-width">width</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLInputElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-input-accept">accept</span>;
attribute DOMString <span title="dom-input-alt">alt</span>;
attribute boolean <span title="dom-input-autocomplete">autocomplete</span>;
attribute boolean <span title="dom-fe-autofocus">autofocus</span>;
attribute boolean <span title="dom-input-defaultChecked">defaultChecked</span>;
attribute boolean <span title="dom-input-checked">checked</span>;
attribute boolean <span title="dom-fe-disabled">disabled</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
readonly attribute <span>FileList</span> <span title="dom-input-files">files</span>;
attribute DOMString <span title="dom-fs-formAction">formAction</span>;
attribute DOMString <span title="dom-fs-formEnctype">formEnctype</span>;
attribute DOMString <span title="dom-fs-formMethod">formMethod</span>;
attribute boolean <span title="dom-fs-formNoValidate">formNoValidate</span>;
attribute DOMString <span title="dom-fs-formTarget">formTarget</span>;
attribute DOMString <span title="dom-dim-height">height</span>;
attribute boolean <span title="dom-input-indeterminate">indeterminate</span>;
readonly attribute <span>HTMLElement</span> <span title="dom-input-list">list</span>;
attribute DOMString <span title="dom-input-max">max</span>;
attribute long <span title="dom-input-maxLength">maxLength</span>;
attribute DOMString <span title="dom-input-min">min</span>;
attribute boolean <span title="dom-input-multiple">multiple</span>;
attribute DOMString <span title="dom-fe-name">name</span>;
attribute DOMString <span title="dom-input-pattern">pattern</span>;
attribute DOMString <span title="dom-input-placeholder">placeholder</span>;
attribute boolean <span title="dom-input-readOnly">readOnly</span>;
attribute boolean <span title="dom-input-required">required</span>;
attribute unsigned long <span title="dom-input-size">size</span>;
attribute DOMString <span title="dom-input-src">src</span>;
attribute DOMString <span title="dom-input-step">step</span>;
attribute DOMString <span title="dom-input-type">type</span>;
attribute DOMString <span title="dom-input-defaultValue">defaultValue</span>;
attribute DOMString <span title="dom-input-value">value</span>;
attribute <span>Date</span> <span title="dom-input-valueAsDate">valueAsDate</span>;
attribute float <span title="dom-input-valueAsNumber">valueAsNumber</span>;
readonly attribute <span>HTMLOptionElement</span> <span title="dom-input-selectedOption">selectedOption</span>;
attribute DOMString <span title="dom-dim-width">width</span>;
void <span title="dom-input-stepUp">stepUp</span>(in optional long n);
void <span title="dom-input-stepDown">stepDown</span>(in optional long n);
readonly attribute boolean <span title="dom-cva-willValidate">willValidate</span>;
readonly attribute <span>ValidityState</span> <span title="dom-cva-validity">validity</span>;
readonly attribute DOMString <span title="dom-cva-validationMessage">validationMessage</span>;
boolean <span title="dom-cva-checkValidatity">checkValidity</span>();
void <span title="dom-cva-setCustomValidity">setCustomValidity</span>(in DOMString error);
readonly attribute <span>NodeList</span> <span title="dom-lfe-labels">labels</span>;
void <span title="dom-textarea/input-select">select</span>();
attribute unsigned long <span title="dom-textarea/input-selectionStart">selectionStart</span>;
attribute unsigned long <span title="dom-textarea/input-selectionEnd">selectionEnd</span>;
void <span title="dom-textarea/input-setSelectionRange">setSelectionRange</span>(in unsigned long start, in unsigned long end);
};</pre>
</dd>
</dl>
<p>The <code>input</code> element <span>represents</span> a typed data field,
usually with a form control to allow the user to edit the data.</p>
<p>The <dfn title="attr-input-type"><code>type</code></dfn>
attribute controls the data type (and associated control) of the
element. It is an <span>enumerated attribute</span>. The following
table lists the keywords and states for the attribute — the
keywords in the left column map to the states in the cell in the
second column on the same row as the keyword.</p>
<table id="attr-input-type-keywords">
<thead>
<tr>
<th> Keyword
<th> State
<th> Data type
<th> Control type
<tbody>
<tr>
<td> <dfn title="attr-input-type-hidden-keyword"><code>hidden</code></dfn>
<td> <span title="attr-input-type-hidden">Hidden</span>
<td> An arbitrary string
<td> n/a
<tr>
<td> <dfn title="attr-input-type-text-keyword"><code>text</code></dfn>
<td> <span title="attr-input-type-text">Text</span>
<td> Text with no line breaks
<td> Text field
<tr>
<td> <dfn title="attr-input-type-search-keyword"><code>search</code></dfn>
<td> <span title="attr-input-type-search">Search</span>
<td> Text with no line breaks
<td> Search field
<tr>
<td> <dfn title="attr-input-type-tel-keyword"><code>tel</code></dfn>
<td> <span title="attr-input-type-tel">Telephone</span>
<td> Text with no line breaks
<td> A text field
<tr>
<td> <dfn title="attr-input-type-url-keyword"><code>url</code></dfn>
<td> <span title="attr-input-type-url">URL</span>
<td> An absolute IRI
<td> A text field
<tr>
<td> <dfn title="attr-input-type-email-keyword"><code>email</code></dfn>
<td> <span title="attr-input-type-email">E-mail</span>
<td> An e-mail address or list of e-mail addresses
<td> A text field
<tr>
<td> <dfn title="attr-input-type-password-keyword"><code>password</code></dfn>
<td> <span title="attr-input-type-password">Password</span>
<td> Text with no line breaks (sensitive information)
<td> Text field that obscures data entry
<tr>
<td> <dfn title="attr-input-type-datetime-keyword"><code>datetime</code></dfn>
<td> <span title="attr-input-type-datetime">Date and Time</span>
<td> A date and time (year, month, day, hour, minute, second, fraction of a second) with the time zone set to UTC
<td> A date and time control
<tr>
<td> <dfn title="attr-input-type-date-keyword"><code>date</code></dfn>
<td> <span title="attr-input-type-date">Date</span>
<td> A date (year, month, day) with no time zone
<td> A date control
<tr>
<td> <dfn title="attr-input-type-month-keyword"><code>month</code></dfn>
<td> <span title="attr-input-type-month">Month</span>
<td> A date consisting of a year and a month with no time zone
<td> A month control
<tr>
<td> <dfn title="attr-input-type-week-keyword"><code>week</code></dfn>
<td> <span title="attr-input-type-week">Week</span>
<td> A date consisting of a week-year number and a week number with no time zone
<td> A week control
<tr>
<td> <dfn title="attr-input-type-time-keyword"><code>time</code></dfn>
<td> <span title="attr-input-type-time">Time</span>
<td> A time (hour, minute, seconds, fractional seconds) with no time zone
<td> A time control
<tr>
<td> <dfn title="attr-input-type-datetime-local-keyword"><code>datetime-local</code></dfn>
<td> <span title="attr-input-type-datetime-local">Local Date and Time</span>
<td> A date and time (year, month, day, hour, minute, second, fraction of a second) with no time zone
<td> A date and time control
<tr>
<td> <dfn title="attr-input-type-number-keyword"><code>number</code></dfn>
<td> <span title="attr-input-type-number">Number</span>
<td> A numerical value
<td> A text field or spinner control
<tr>
<td> <dfn title="attr-input-type-range-keyword"><code>range</code></dfn>
<td> <span title="attr-input-type-range">Range</span>
<td> A numerical value, with the extra semantic that the exact value is not important
<td> A slider control or similar
<tr>
<td> <dfn title="attr-input-type-color-keyword"><code>color</code></dfn>
<td> <span title="attr-input-type-color">Color</span>
<td> An sRGB color with 8-bit red, green, and blue components
<td> A color well
<tr>
<td> <dfn title="attr-input-type-checkbox-keyword"><code>checkbox</code></dfn>
<td> <span title="attr-input-type-checkbox">Checkbox</span>
<td> A set of zero or more values from a predefined list
<td> A checkbox
<tr>
<td> <dfn title="attr-input-type-radio-keyword"><code>radio</code></dfn>
<td> <span title="attr-input-type-radio">Radio Button</span>
<td> An enumerated value
<td> A radio button
<tr>
<td> <dfn title="attr-input-type-file-keyword"><code>file</code></dfn>
<td> <span title="attr-input-type-file">File Upload</span>
<td> Zero or more files each with a <span>MIME type</span> and optionally a file name
<td> A label and a button
<tr>
<td> <dfn title="attr-input-type-submit-keyword"><code>submit</code></dfn>
<td> <span title="attr-input-type-submit">Submit Button</span>
<td> An enumerated value, with the extra semantic that it must be the last value selected and initiates form submission
<td> A button
<tr>
<td> <dfn title="attr-input-type-image-keyword"><code>image</code></dfn>
<td> <span title="attr-input-type-image">Image Button</span>
<td> A coordinate, relative to a particular image's size, with the extra semantic that it must be the last value selected and initiates form submission
<td> Either a clickable image, or a button
<tr>
<td> <dfn title="attr-input-type-reset-keyword"><code>reset</code></dfn>
<td> <span title="attr-input-type-reset">Reset Button</span>
<td> n/a
<td> A button
<tr>
<td> <dfn title="attr-input-type-button-keyword"><code>button</code></dfn>
<td> <span title="attr-input-type-button">Button</span>
<td> n/a
<td> A button
</table>
<p>The <i>missing value default</i> is the <span
title="attr-input-type-text">Text</span> state.</p>
<p>Which of the <code title="attr-input-accept">accept</code>, <code
title="attr-input-alt">alt</code>, <code
title="attr-input-autocomplete">autocomplete</code>, <code
title="attr-input-checked">checked</code>, <code
title="attr-fs-formaction">formaction</code>, <code
title="attr-fs-formenctype">formenctype</code>, <code
title="attr-fs-formmethod">formmethod</code>, <code
title="attr-fs-formnovalidate">formnovalidate</code>, <code
title="attr-fs-formtarget">formtarget</code>, <code
title="attr-dim-height">height</code>, <code
title="attr-input-list">list</code>, <code
title="attr-input-max">max</code>, <code
title="attr-input-maxlength">maxlength</code>, <code
title="attr-input-min">min</code>, <code
title="attr-input-multiple">multiple</code>, <code
title="attr-input-pattern">pattern</code>, <code
title="attr-input-placeholder">placeholder</code>, <code
title="attr-input-readonly">readonly</code>, <code
title="attr-input-required">required</code>, <code
title="attr-input-size">size</code>, <code
title="attr-input-src">src</code>, <code
title="attr-input-step">step</code>, and <code
title="attr-dim-width">width</code> content attributes, the <code
title="dom-input-checked">checked</code>, <code
title="dom-input-files">files</code>, <code
title="dom-input-valueAsDate">valueAsDate</code>, <code
title="dom-input-valueAsNumber">valueAsNumber</code>, <code
title="dom-input-list">list</code>, and <code
title="dom-input-selectedOption">selectedOption</code> IDL
attributes, the <code
title="dom-textarea/input-select">select()</code> method, the <code
title="dom-textarea/input-selectionStart">selectionStart</code> and
<code title="dom-textarea/input-selectionEnd">selectionEnd</code>
IDL attributes, the <code
title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>
method, the <code title="dom-input-stepUp">stepUp()</code> and
<code title="dom-input-stepDown">stepDown()</code> methods, and the
<code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply to an
<code>input</code> element depends on the state of its <code
title="attr-input-type">type</code> attribute. The following table
<span class="impl">is non-normative and</span> summarizes which of
those content attributes, IDL attributes, methods, and events apply
to each state:</p>
<table class="applies" id="input-type-attr-summary">
<thead>
<tr>
<th>
<th> <span title=""><span title="attr-input-type-hidden">Hidden</span></span>
<th> <span title=""><span title="attr-input-type-text">Text</span>,</span>
<span title=""><span title="attr-input-type-search">Search</span>,</span>
<span title=""><span title="attr-input-type-url">URL</span>,</span>
<span title=""><span title="attr-input-type-tel">Telephone</span></span>
<th> <span title=""><span title="attr-input-type-email">E-mail</span></span>
<th> <span title=""><span title="attr-input-type-password">Password</span></span>
<th> <span title=""><span title="attr-input-type-datetime">Date and Time</span>,</span>
<span title=""><span title="attr-input-type-date">Date</span>,</span>
<span title=""><span title="attr-input-type-month">Month</span>,</span>
<span title=""><span title="attr-input-type-week">Week</span>,</span>
<span title=""><span title="attr-input-type-time">Time</span></span>
<th> <span title=""><span title="attr-input-type-datetime-local">Local Date and Time</span>,</span>
<span title=""><span title="attr-input-type-number">Number</span></span>
<th> <span title=""><span title="attr-input-type-range">Range</span></span>
<th> <span title=""><span title="attr-input-type-color">Color</span></span>
<th> <span title=""><span title="attr-input-type-checkbox">Checkbox</span>,</span>
<span title=""><span title="attr-input-type-radio">Radio Button</span></span>
<th> <span title=""><span title="attr-input-type-file">File Upload</span></span>
<th> <span title=""><span title="attr-input-type-submit">Submit Button</span></span>
<th> <span title=""><span title="attr-input-type-image">Image Button</span></span>
<th> <span title=""><span title="attr-input-type-reset">Reset Button</span>,</span>
<span title=""><span title="attr-input-type-button">Button</span></span>
<tbody>
<tr>
<th scope="rowgroup" colspan="14">Content attributes
<tr>
<th> <code title="attr-input-accept">accept</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="yes"> Yes <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-alt">alt</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-autocomplete">autocomplete</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="yes"> Yes <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-checked">checked</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="yes"> Yes <!-- Checkbox -->
<!-- <td class="yes"> Yes Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-fs-formaction">formaction</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="yes"> Yes <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-fs-formenctype">formenctype</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="yes"> Yes <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-fs-formmethod">formmethod</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="yes"> Yes <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-fs-formnovalidate">formnovalidate</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="yes"> Yes <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-fs-formtarget">formtarget</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="yes"> Yes <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-dim-height">height</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-list">list</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="yes"> Yes <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-max">max</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-maxlength">maxlength</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-min">min</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-multiple">multiple</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="yes"> Yes <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-pattern">pattern</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-placeholder">placeholder</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-readonly">readonly</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-required">required</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="yes"> Yes <!-- Checkbox -->
<!-- <td class="yes"> Yes Radio Button -->
<td class="yes"> Yes <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-size">size</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-src">src</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-input-step">step</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="attr-dim-width">width</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="yes"> Yes <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tbody>
<tr>
<th scope="rowgroup" colspan="14">IDL attributes and methods
<tr>
<th> <code title="dom-input-checked">checked</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="yes"> Yes <!-- Checkbox -->
<!-- <td class="yes"> Yes Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-input-files">files</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="yes"> Yes <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr class="impl">
<th> <code title="dom-input-value">value</code>
<td class="yes"> <span title="dom-input-value-default">default</span> <!-- Hidden -->
<td class="yes"> <span title="dom-input-value-value">value</span> <!-- Text -->
<!-- <td class="yes"> <span title="dom-input-value-value">value</span> Search -->
<!-- <td class="yes"> <span title="dom-input-value-value">value</span> URL -->
<td class="yes"> <span title="dom-input-value-value">value</span> <!-- E-mail -->
<td class="yes"> <span title="dom-input-value-value">value</span> <!-- Password -->
<td class="yes"> <span title="dom-input-value-value">value</span> <!-- Date and Time -->
<!-- <td class="yes"> <span title="dom-input-value-value">value</span> Date -->
<!-- <td class="yes"> <span title="dom-input-value-value">value</span> Month -->
<!-- <td class="yes"> <span title="dom-input-value-value">value</span> Week -->
<!-- <td class="yes"> <span title="dom-input-value-value">value</span> Time -->
<td class="yes"> <span title="dom-input-value-value">value</span> <!-- Local Date and Time -->
<!-- <td class="yes"> <span title="dom-input-value-value">value</span> Number -->
<td class="yes"> <span title="dom-input-value-value">value</span> <!-- Range -->
<td class="yes"> <span title="dom-input-value-value">value</span> <!-- Color -->
<td class="yes"> <span title="dom-input-value-default-on">default/on</span> <!-- Checkbox -->
<!-- <td class="yes"> <span title="dom-input-value-default-on">default/on</span> Radio Button -->
<td class="yes"> <span title="dom-input-value-filename">filename</span> <!-- File Upload -->
<td class="yes"> <span title="dom-input-value-default">default</span> <!-- Submit Button -->
<td class="yes"> <span title="dom-input-value-default">default</span> <!-- Image Button -->
<td class="yes"> <span title="dom-input-value-default">default</span> <!-- Reset Button -->
<!-- <td class="yes"> <span title="dom-input-value-default">default</span> Button -->
<tr>
<th> <code title="dom-input-valueAsDate">valueAsDate</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-input-valueAsNumber">valueAsNumber</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-input-list">list</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="yes"> Yes <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-input-selectedOption">selectedOption</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="yes"> Yes <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-textarea/input-select">select()</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-textarea/input-selectionStart">selectionStart</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-textarea/input-selectionEnd">selectionEnd</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="no"> · <!-- Date and Time -->
<!-- <td class="no"> · Date -->
<!-- <td class="no"> · Month -->
<!-- <td class="no"> · Week -->
<!-- <td class="no"> · Time -->
<td class="no"> · <!-- Local Date and Time -->
<!-- <td class="no"> · Number -->
<td class="no"> · <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-input-stepDown">stepDown()</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <code title="dom-input-stepUp">stepUp()</code>
<td class="no"> · <!-- Hidden -->
<td class="no"> · <!-- Text -->
<!-- <td class="no"> · Search -->
<!-- <td class="no"> · URL -->
<td class="no"> · <!-- E-mail -->
<td class="no"> · <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="no"> · <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tbody>
<tr>
<th scope="rowgroup" colspan="14">Events
<tr>
<th> <span title=""><code title="event-input-input">input</code> event</span>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="yes"> Yes <!-- Color -->
<td class="no"> · <!-- Checkbox -->
<!-- <td class="no"> · Radio Button -->
<td class="no"> · <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
<tr>
<th> <span title=""><code title="event-input-change">change</code> event</span>
<td class="no"> · <!-- Hidden -->
<td class="yes"> Yes <!-- Text -->
<!-- <td class="yes"> Yes Search -->
<!-- <td class="yes"> Yes URL -->
<td class="yes"> Yes <!-- E-mail -->
<td class="yes"> Yes <!-- Password -->
<td class="yes"> Yes <!-- Date and Time -->
<!-- <td class="yes"> Yes Date -->
<!-- <td class="yes"> Yes Month -->
<!-- <td class="yes"> Yes Week -->
<!-- <td class="yes"> Yes Time -->
<td class="yes"> Yes <!-- Local Date and Time -->
<!-- <td class="yes"> Yes Number -->
<td class="yes"> Yes <!-- Range -->
<td class="yes"> Yes <!-- Color -->
<td class="yes"> Yes <!-- Checkbox -->
<!-- <td class="yes"> Yes Radio Button -->
<td class="yes"> Yes <!-- File Upload -->
<td class="no"> · <!-- Submit Button -->
<td class="no"> · <!-- Image Button -->
<td class="no"> · <!-- Reset Button -->
<!-- <td class="no"> · Button -->
</table>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute changes state, and
when the element is first created, the element's rendering and
behavior must change to the new state's accordingly and the
<dfn>value sanitization algorithm</dfn>, if one is defined for the
<code title="attr-input-type">type</code> attribute's new state,
must be invoked.</p>
<p>Each <code>input</code> element has a <span
title="concept-fe-value">value</span>, which is exposed by the <code
title="dom-input-value">value</code> IDL attribute. Some states
define an <dfn title="concept-input-value-string-number">algorithm
to convert a string to a number</dfn>, an <dfn
title="concept-input-value-number-string">algorithm to convert a
number to a string</dfn>, an <dfn
title="concept-input-value-string-date">algorithm to convert a
string to a <code>Date</code> object</dfn>, and an <dfn
title="concept-input-value-date-string">algorithm to convert a
<code>Date</code> object to a string</dfn>, which are used by
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>,
<code title="attr-input-step">step</code>,
<code title="dom-input-valueAsDate">valueAsDate</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>,
<code title="dom-input-stepDown">stepDown()</code>, and
<code title="dom-input-stepUp">stepUp()</code>.</p>
<p>Each <code>input</code> element has a boolean <dfn
title="concept-input-value-dirty-flag">dirty value flag</dfn>. When
it is true, the element is said to have a <dfn
title="concept-input-value-dirty"><i>dirty value</i></dfn>. The
<span title="concept-input-value-dirty-flag">dirty value flag</span>
must be initially set to false when the element is created, and must
be set to true whenever the user interacts with the control in a way
that changes the <span title="concept-fe-value">value</span>.</p>
</div>
<p>The <dfn title="attr-input-value"><code>value</code></dfn>
content attribute gives the default <span
title="concept-fe-value">value</span> of the <code>input</code>
element. <span class="impl">When the <code
title="attr-input-value">value</code> content attribute is added,
set, or removed, if the control does not have a <i
title="concept-input-value-dirty">dirty value</i>, the user agent
must set the <span title="concept-fe-value">value</span> of the
element to the value of the <code
title="attr-input-value">value</code> content attribute, if there is
one, or the empty string otherwise, and then run the current
<span>value sanitization algorithm</span>, if one is
defined.</span></p>
<div class="impl">
<p>Each <code>input</code> element has a <span
title="concept-fe-checked">checkedness</span>, which is exposed by
the <code title="dom-input-checked">checked</code> IDL
attribute.</p>
<p>Each <code>input</code> element has a boolean <dfn
title="concept-input-checked-dirty-flag">dirty checkedness
flag</dfn>. When it is true, the element is said to have a <dfn
title="concept-input-checked-dirty"><i>dirty
checkedness</i></dfn>. The <span
title="concept-input-checked-dirty-flag">dirty checkedness
flag</span> must be initially set to false when the element is
created, and must be set to true whenever the user interacts with
the control in a way that changes the <span
title="concept-fe-checked">checkedness</span>.</p>
</div>
<p>The <dfn title="attr-input-checked"><code>checked</code></dfn>
content attribute is a <span>boolean attribute</span> that gives the
default <span title="concept-fe-checked">checkedness</span> of the
<code>input</code> element. <span class="impl">When the <code
title="attr-input-checked">checked</code> content attribute is
added, if the control does not have <i
title="concept-input-checked-dirty">dirty checkedness</i>, the user
agent must set the <span
title="concept-fe-checked">checkedness</span> of the element to
true; when the <code title="attr-input-checked">checked</code>
content attribute is removed, if the control does not have <i
title="concept-input-checked-dirty">dirty checkedness</i>, the user
agent must set the <span
title="concept-fe-checked">checkedness</span> of the element to
false.</span></p>
<div class="impl">
<p>The <span title="concept-form-reset-control">reset
algorithm</span> for <code>input</code> elements is to set the <span
title="concept-input-value-dirty-flag">dirty value flag</span> and
<span title="concept-input-checked-dirty-flag">dirty checkedness
flag</span> back to false, set the <span
title="concept-fe-value">value</span> of the element to the value of
the <code title="attr-input-value">value</code> content attribute,
if there is one, or the empty string otherwise, set the <span
title="concept-fe-checked">checkedness</span> of the element to true
if the element has a <code title="attr-input-checked">checked</code>
content attribute and false if it does not, and then invoke the
<span>value sanitization algorithm</span>, if the <code
title="attr-input-type">type</code> attribute's current state
defines one.</p>
<p>Each <code>input</code> element is either <dfn
title="concept-input-mutable"><i>mutable</i></dfn> or <dfn
title="concept-input-immutable"><i>immutable</i></dfn>. Except where
otherwise specified, an <code>input</code> element is always <i
title="concept-input-mutable">mutable</i>. Similarly, except where
otherwise specified, the user agent should not allow the user to
modify the element's <span title="concept-fe-value">value</span> or
<span title="concept-fe-checked">checkedness</span>.</p>
<p>When an <code>input</code> element is <span
title="concept-fe-disabled">disabled</span>, it is <i
title="concept-input-immutable">immutable</i>.</p>
<p>When an <code>input</code> element does not have a
<code>Document</code> node as one of its ancestors (i.e. when it is
not in the document), it is <i
title="concept-input-immutable">immutable</i>.</p> <!-- XBL2 spec
point -->
<p class="note">The <code
title="attr-input-readonly">readonly</code> attribute can also in
some cases (e.g. for the <span
title="attr-input-type-date">Date</span> state, but not the <span
title="attr-input-type-checkbox">Checkbox</span> state) make an
<code>input</code> element <i
title="concept-input-immutable">immutable</i>.</p>
<p>When an <code>input</code> element is cloned, the element's <span
title="concept-fe-value">value</span>, <span
title="concept-input-value-dirty-flag">dirty value flag</span>,
<span title="concept-fe-checked">checkedness</span>, and <span
title="concept-input-checked-dirty-flag">dirty checkedness
flag</span> must be propagated to the clone when it is created.</p>
</div>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>input</code> element with its
<span>form owner</span>. The <code title="attr-fe-name">name</code>
attribute represents the element's name. The <code
title="attr-fe-disabled">disabled</code> attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The <code title="attr-fe-autofocus">autofocus</code>
attribute controls focus.</p>
<div class="impl">
<p>The <dfn
title="dom-input-indeterminate"><code>indeterminate</code></dfn> IDL
attribute must initially be set to false. On getting, it must return
the last value it was set to. On setting, it must be set to the new
value. It has no effect except for changing the appearance of <span
title="attr-input-type-checkbox">checkbox</span> controls.</p>
<p>The <dfn title="dom-input-accept"><code>accept</code></dfn>, <dfn
title="dom-input-alt"><code>alt</code></dfn>, <dfn
title="dom-input-autocomplete"><code>autocomplete</code></dfn>, <dfn
title="dom-input-max"><code>max</code></dfn>, <dfn
title="dom-input-min"><code>min</code></dfn>, <dfn
title="dom-input-multiple"><code>multiple</code></dfn>, <dfn
title="dom-input-pattern"><code>pattern</code></dfn>, <dfn
title="dom-input-placeholder"><code>placeholder</code></dfn>, <dfn
title="dom-input-required"><code>required</code></dfn>, <dfn
title="dom-input-size"><code>size</code></dfn>, <dfn
title="dom-input-src"><code>src</code></dfn>, <dfn
title="dom-input-step"><code>step</code></dfn>, and <dfn
title="dom-input-type"><code>type</code></dfn> IDL attributes must
<span>reflect</span> the respective content attributes of the same
name. The <dfn
title="dom-input-maxLength"><code>maxLength</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-input-maxlength">maxlength</code> content attribute,
<span>limited to only non-negative numbers</span>. The <dfn
title="dom-input-readOnly"><code>readOnly</code></dfn> IDL attribute
must <span>reflect</span> the <code
title="attr-input-readonly">readonly</code> content attribute. The
<dfn
title="dom-input-defaultChecked"><code>defaultChecked</code></dfn>
IDL attribute must <span>reflect</span> the <code
title="attr-input-checked">checked</code> content attribute. The
<dfn title="dom-input-defaultValue"><code>defaultValue</code></dfn>
IDL attribute must <span>reflect</span> the <code
title="attr-input-value">value</code> content attribute.</p>
<p>The <code title="dom-cva-willValidate">willValidate</code>, <code
title="dom-cva-validity">validity</code>, and <code
title="dom-cva-validationMessage">validationMessage</code>
attributes, and the <code
title="dom-cva-checkValidatity">checkValidity()</code> and <code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
methods, are part of the <span>constraint validation API</span>. The
<code title="dom-lfe-labels">labels</code> attribute provides a list
of the element's <code>label</code>s. The <code
title="dom-textarea/input-select">select()</code>, <code
title="dom-textarea/input-selectionStart">selectionStart</code>,
<code title="dom-textarea/input-selectionEnd">selectionEnd</code>,
and <code
title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>
methods and attributes expose the element's text selection.</p>
</div>
<h5>States of the <code title="attr-input-type">type</code> attribute</h5>
<h6><dfn title="attr-input-type-hidden">Hidden</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-hidden">Hidden</span> state, the rules in
this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a value
that is not intended to be examined or manipulated by the user.</p>
<div class="impl">
<p><strong>Constraint validation</strong>: If an <code>input</code>
element's <code title="attr-input-type">type</code> attribute is in
the <span title="attr-input-type-hidden">Hidden</span> state, it is
<span>barred from constraint validation</span>.</p>
</div>
<p>If the <code title="attr-input-value">name</code> attribute is
present and has a value that is a <span>case-sensitive</span> match
for the string "<code title="">_charset_</code>", then the element's
<code title="attr-input-value">value</code> attribute must be
omitted.</p>
<div class="bookkeeping">
<p>The
<code title="dom-input-value">value</code>
IDL attribute applies to this element and is
in mode <span title="dom-input-value-default">default</span>.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-autocomplete">autocomplete</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-required">required</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code class="no-backref"
title="event-input-input">input</code> and <code class="no-backref"
title="event-input-change">change</code> events do not apply.</p>
</div>
<h6><dfn title="attr-input-type-text">Text</dfn> state and <dfn title="attr-input-type-search">Search</dfn> state</h6>
<!-- v2 idea: applying input masks to <input>, e.g. for entering
data with slashes and dashes (ack Greg Kilwein)
-->
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-text">Text</span> state or the <span
title="attr-input-type-search">Search</span> state, the rules in
this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a one line
plain text edit control for the element's <span
title="concept-fe-value">value</span>.</p>
<p class="note">The difference between the <span
title="attr-input-type-text">Text</span> state and the <span
title="attr-input-type-search">Search</span> state is primarily
stylistic: on platforms where search fields are distinguished from
regular text fields, the <span
title="attr-input-type-search">Search</span> state might result in
an appearance consistent with the platform's search fields rather
than appearing like a regular text field.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
its <span title="concept-fe-value">value</span> should be editable
by the user. User agents must not allow users to insert U+000A LINE
FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the
element's <span title="concept-fe-value">value</span>.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that contains no U+000A LINE FEED (LF)
or U+000D CARRIAGE RETURN (CR) characters.</p>
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: <span>Strip line breaks</span> from the <span
title="concept-fe-value">value</span>.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-maxlength">maxlength</code>,
<code title="attr-input-pattern">pattern</code>,
<code title="attr-input-placeholder">placeholder</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-size">size</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-selectedOption">selectedOption</code>,
<code title="dom-textarea/input-selectionStart">selectionStart</code>,
<code title="dom-textarea/input-selectionEnd">selectionEnd</code>, and
<code title="dom-input-value">value</code> IDL attributes;
<code title="dom-textarea/input-select">select()</code> and
<code title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-input-stepDown">stepDown()</code> and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-tel">Telephone</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-tel">Telephone</span> state, the rules in
this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for editing a telephone number given in the element's <span
title="concept-fe-value">value</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
its <span title="concept-fe-value">value</span> should be editable
by the user. User agents may change the punctuation of <span
title="concept-fe-value">values</span> that the user enters. User
agents must not allow users to insert U+000A LINE FEED (LF) or
U+000D CARRIAGE RETURN (CR) characters into the element's <span
title="concept-fe-value">value</span>.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that contains no U+000A LINE FEED (LF)
or U+000D CARRIAGE RETURN (CR) characters.</p>
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: <span>Strip line breaks</span> from the <span
title="concept-fe-value">value</span>.</p>
</div>
<p class="note">Unlike the <span
title="attr-input-type-url">URL</span> and <span
title="attr-input-type-email">E-mail</span> types, the <span
title="attr-input-type-tel">Telephone</span> type does not enforce a
particular syntax. This is intentional; in practice, telephone
number fields tend to be free-form fields, because there are a wide
variety of valid phone numbers. Systems that need to enforce a
particular format are encouraged to use the <code
title="dom-cva-setCustomValidity">setCustomValidity()</code> method
to hook into the client-side validation mechanism.</p>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-maxlength">maxlength</code>,
<code title="attr-input-pattern">pattern</code>,
<code title="attr-input-placeholder">placeholder</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-size">size</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-selectedOption">selectedOption</code>,
<code title="dom-textarea/input-selectionStart">selectionStart</code>,
<code title="dom-textarea/input-selectionEnd">selectionEnd</code>, and
<code title="dom-input-value">value</code> IDL attributes;
<code title="dom-textarea/input-select">select()</code> and
<code title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-input-stepDown">stepDown()</code> and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-url">URL</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-url">URL</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for editing a single <span>absolute URL</span> given in the
element's <span title="concept-fe-value">value</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the URL represented
by its <span title="concept-fe-value">value</span>. User agents may
allow the user to set the <span
title="concept-fe-value">value</span> to a string that is not a
<span title="valid URL">valid</span> <span>absolute URL</span>, but
may also or instead automatically escape characters entered by the
user so that the <span title="concept-fe-value">value</span> is
always a <span title="valid URL">valid</span> <span>absolute
URL</span> (even if that isn't the actual value seen and edited by
the user in the interface). User agents should allow the user to set
the <span title="concept-fe-value">value</span> to the empty
string. User agents must not allow users to insert U+000A LINE FEED
(LF) or U+000D CARRIAGE RETURN (CR) characters into the <span
title="concept-fe-value">value</span>.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span title="valid
URL">valid</span> <span>absolute URL</span>.</p>
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: <span>Strip line breaks</span> from the <span
title="concept-fe-value">value</span>.</p>
<p><strong>Constraint validation</strong>: While the <span
title="concept-fe-value">value</span> of the element is not a <span
title="valid URL">valid</span> <span>absolute URL</span>, the
element is <span>suffering from a type mismatch</span>.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-maxlength">maxlength</code>,
<code title="attr-input-pattern">pattern</code>,
<code title="attr-input-placeholder">placeholder</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-size">size</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-selectedOption">selectedOption</code>,
<code title="dom-textarea/input-selectionStart">selectionStart</code>,
<code title="dom-textarea/input-selectionEnd">selectionEnd</code>, and
<code title="dom-input-value">value</code> IDL attributes;
<code title="dom-textarea/input-select">select()</code> and
<code title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-input-stepDown">stepDown()</code> and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-email">E-mail</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-email">E-mail</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for editing a list of e-mail addresses given in the element's <span
title="concept-fe-value">value</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the e-mail addresses
represented by its <span title="concept-fe-value">value</span>. If
the <code title="attr-input-multiple">multiple</code> attribute is
specified, then the user agent should allow the user to select or
provide multiple addresses; otherwise, the user agent should act in
a manner consistent with expecting the user to provide a single
e-mail address. User agents may allow the user to set the <span
title="concept-fe-value">value</span> to a string that is not a
<span>valid e-mail address list</span>. User agents should allow the
user to set the <span title="concept-fe-value">value</span> to the
empty string. User agents must not allow users to insert U+000A LINE
FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the <span
title="concept-fe-value">value</span>. User agents may transform the
<span title="concept-fe-value">value</span> for display and editing
(e.g. converting punycode in the <span
title="concept-fe-value">value</span> to IDN in the display and vice
versa).</p>
</div>
<p>If the <code title="attr-input-multiple">multiple</code>
attribute is specified on the element, then the <code
title="attr-input-value">value</code> attribute, if specified, must
have a value that is a <span>valid e-mail address list</span>;
otherwise, the <code title="attr-input-value">value</code>
attribute, if specified, must have a value that is a single
<span>valid e-mail address</span>.</p>
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: <span>Strip line breaks</span> from the <span
title="concept-fe-value">value</span>.</p>
<p><strong>Constraint validation</strong>: If the <code
title="attr-input-multiple">multiple</code> attribute is specified
on the element, then, while the <span
title="concept-fe-value">value</span> of the element is not a
<span>valid e-mail address list</span>, the element is
<span>suffering from a type mismatch</span>; otherwise, while the
<span title="concept-fe-value">value</span> of the element is not a
single <span>valid e-mail address</span>, the element is
<span>suffering from a type mismatch</span>.</p>
</div>
<p>A <dfn>valid e-mail address list</dfn> is a <span>set of
comma-separated tokens</span>, where each token is itself a
<span>valid e-mail address</span>. <span class="impl">To obtain the
list of tokens from a <span>valid e-mail address list</span>, the
user agent must <span title="split a string on commas">split the
string on commas</span>.</span></p>
<p>A <dfn>valid e-mail address</dfn> is a string that matches the
ABNF production <code
title="">1*( atext / "." ) "@" ldh-str 1*( "." ldh-str )</code>
where <code title="">atext</code> is defined in RFC 5322 section
3.2.3, and <code title="">ldh-str</code> is defined in RFC 1034
section 3.5. <a href="#refsABNF">[ABNF]</a> <a
href="#refsRFC5322">[RFC5322]</a> <a
href="#refsRFC1034">[RFC1034]</a></p> <!-- Domain syntax based on
section 3.5 of [RFC1034] and section 2.1 of [RFC1123] -->
<p class="note">This requirement is a <span>willful violation</span>
of RFC 5322, which defines a syntax for e-mail addresses that is
simultaneously too strict (before the "@" character), too vague
(after the "@" character), and too lax (allowing comments, white
space characters, and quoted strings in manners unfamiliar to most
users) to be of practical use here.</p>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-maxlength">maxlength</code>,
<code title="attr-input-multiple">multiple</code>,
<code title="attr-input-pattern">pattern</code>,
<code title="attr-input-placeholder">placeholder</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-size">size</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-selectedOption">selectedOption</code>,
<code title="dom-textarea/input-selectionStart">selectionStart</code>,
<code title="dom-textarea/input-selectionEnd">selectionEnd</code>, and
<code title="dom-input-value">value</code> IDL attributes;
<code title="dom-textarea/input-select">select()</code> and
<code title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-input-stepDown">stepDown()</code> and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-password">Password</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-password">Password</span> state, the rules in
this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a one line
plain text edit control for the element's <span
title="concept-fe-value">value</span>. The user agent should obscure
the value so that people other than the user cannot see it.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
its <span title="concept-fe-value">value</span> should be editable
by the user. User agents must not allow users to insert U+000A LINE
FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the <span
title="concept-fe-value">value</span>.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that contains no U+000A LINE FEED (LF)
or U+000D CARRIAGE RETURN (CR) characters.</p>
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: <span>Strip line breaks</span> from the <span
title="concept-fe-value">value</span>.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-maxlength">maxlength</code>,
<code title="attr-input-pattern">pattern</code>,
<code title="attr-input-placeholder">placeholder</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-size">size</code> content attributes;
<code title="dom-textarea/input-selectionStart">selectionStart</code>,
<code title="dom-textarea/input-selectionEnd">selectionEnd</code>, and
<code title="dom-input-value">value</code> IDL attributes;
<code title="dom-textarea/input-select">select()</code>, and
<code title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-input-stepDown">stepDown()</code> and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-datetime">Date and Time</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-datetime">Date and Time</span> state, the
rules in this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
specific <span title="concept-datetime">global date and
time</span>. <span class="impl">User agents may display the date and
time in whatever time zone is appropriate for the user.</span></p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the <span
title="concept-datetime">global date and time</span> represented by
its <span title="concept-fe-value">value</span>, as obtained by
<span title="parse a global date and time string">parsing a global
date and time</span> from it. User agents must not allow the user to
set the <span title="concept-fe-value">value</span> to a string that
is not a <span>valid global date and time string</span> expressed in
UTC, though user agents may allow the user to set and view the time
in another time zone and silently translate the time to and from the
UTC time zone in the <span title="concept-fe-value">value</span>. If
the user agent provides a user interface for selecting a <span
title="concept-datetime">global date and time</span>, then the <span
title="concept-fe-value">value</span> must be set to a <span>valid
global date and time string</span> expressed in UTC representing the
user's selection. User agents should allow the user to set the <span
title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid global date and
time string</span>.</p> <!-- ok to set out-of-range value, we never
know when we might have to represent bogus input -->
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is a <span>valid global date and time string</span>,
then adjust the time so that the <span
title="concept-fe-value">value</span> represents the same point in
time but expressed in the UTC time zone, otherwise, set it to the
empty string instead.</p>
</div>
<p>The <code title="attr-input-min">min</code> attribute, if
specified, must have a value that is a <span>valid global date and
time string</span>. The <code title="attr-input-max">max</code>
attribute, if specified, must have a value that is a <span>valid
global date and time string</span>.</p>
<p>The <code title="attr-input-step">step</code> attribute is
expressed in seconds. <span class="impl">The <span
title="concept-input-step-scale">step scale factor</span> is 1000
(which converts the seconds to milliseconds, as used in the other
algorithms).</span> The <span
title="concept-input-step-default">default step</span> is 60
seconds.</p>
<div class="impl">
<p>When the element is <span>suffering from a step mismatch</span>,
the user agent may round the element's <span
title="concept-fe-value">value</span> to the nearest <span
title="concept-datetime">global date and time</span> for which the
element would not <span title="suffering from a step
mismatch">suffer from a step mismatch</span>.</p>
<p><strong>The <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span>, given a string <var title="">input</var>,
is as follows</strong>: If <span title="parse a global date and time
string">parsing a global date and time</span> from <var
title="">input</var> results in an error, then return an error;
otherwise, return the number of milliseconds elapsed from midnight
UTC on the morning of 1970-01-01 (the time represented by the value
"<code title="">1970-01-01T00:00:00.0Z</code>") to the parsed <span
title="concept-datetime">global date and time</span>, ignoring leap
seconds.</p>
<p><strong>The <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, given a number <var title="">input</var>,
is as follows</strong>: Return a <span>valid global date and time
string</span> expressed in UTC that represents the <span
title="concept-datetime">global date and time</span> that is <var
title="">input</var> milliseconds after midnight UTC on the morning
of 1970-01-01 (the time represented by the value "<code
title="">1970-01-01T00:00:00.0Z</code>").</p>
<p><strong>The <span
title="concept-input-value-string-date">algorithm to convert a
string to a <code>Date</code> object</span>, given a string <var
title="">input</var>, is as follows</strong>: If <span title="parse
a global date and time string">parsing a global date and time</span>
from <var title="">input</var> results in an error, then return an
error; otherwise, return a <code>Date</code> object representing the
parsed <span title="concept-datetime">global date and time</span>,
expressed in UTC.</p>
<p><strong>The <span
title="concept-input-value-date-string">algorithm to convert a
<code>Date</code> object to a string</span>, given a
<code>Date</code> object <var title="">input</var>, is as
follows</strong>: Return a <span>valid global date and time
string</span> expressed in UTC that represents the <span
title="concept-datetime">global date and time</span> that is
represented by <var title="">input</var>.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-step">step</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>,
<code title="dom-input-valueAsDate">valueAsDate</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes;
<code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>, and
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code> and
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
</div>
<div class="example">
<p>The following fragment shows part of a calendar application. A
user can specify a date and time for a meeting (in his local time
zone, probably, though the user agent can allow the user to change
that), and since the submitted data includes the time-zone offset,
the application can ensure that the meeting is shown at the correct
time regardless of the time zones used by all the participants.</p>
<pre><fieldset>
<legend>Add Meeting</legend>
<p><label>Meeting name: <input type=text name="meeting.label"></label>
<p><label>Meeting time: <input type=datetime name="meeting.start"></label>
</fieldset></pre>
<p>Had the application used the <code
title="attr-input-type-datetime-local">datetime-local</code> type
instead, the calendar application would have also had to explicitly
determine which time zone the user intended.</p>
</div>
<h6><dfn title="attr-input-type-date">Date</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-date">Date</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
specific <span title="concept-date">date</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the <span
title="concept-date">date</span> represented by its <span
title="concept-fe-value">value</span>, as obtained by <span
title="parse a date string">parsing a date</span> from it. User
agents must not allow the user to set the <span
title="concept-fe-value">value</span> to a string that is not a
<span>valid date string</span>. If the user agent provides a user
interface for selecting a <span title="concept-date">date</span>,
then the <span title="concept-fe-value">value</span> must be set to
a <span>valid date string</span> representing the user's
selection. User agents should allow the user to set the <span
title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid date
string</span>.</p> <!-- ok to set out-of-range value, we never know
when we might have to represent bogus input -->
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is not a <span>valid date string</span>, then set it
to the empty string instead.</p>
</div>
<p>The <code title="attr-input-min">min</code> attribute, if
specified, must have a value that is a <span>valid date
string</span>. The <code title="attr-input-max">max</code>
attribute, if specified, must have a value that is a <span>valid
date string</span>.</p>
<p>The <code title="attr-input-step">step</code> attribute is
expressed in days. <span class="impl">The <span
title="concept-input-step-scale">step scale factor</span> is
86,400,000 (which converts the days to milliseconds, as used in the
other algorithms).</span> The <span
title="concept-input-step-default">default step</span> is 1 day.</p>
<div class="impl">
<p>When the element is <span>suffering from a step mismatch</span>,
the user agent may round the element's <span
title="concept-fe-value">value</span> to the nearest <span
title="concept-date">date</span> for which the element would not
<span title="suffering from a step mismatch">suffer from a step
mismatch</span>.</p>
<p><strong>The <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span>, given a string <var title="">input</var>,
is as follows</strong>: If <span title="parse a date string">parsing
a date</span> from <var title="">input</var> results in an error,
then return an error; otherwise, return the number of milliseconds
elapsed from midnight UTC on the morning of 1970-01-01 (the time
represented by the value "<code
title="">1970-01-01T00:00:00.0Z</code>") to midnight UTC on the
morning of the parsed <span title="concept-date">date</span>,
ignoring leap seconds.</p>
<p><strong>The <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, given a number <var title="">input</var>,
is as follows</strong>: Return a <span>valid date string</span> that
represents the <span title="concept-date">date</span> that, in UTC,
is current <var title="">input</var> milliseconds after midnight UTC
on the morning of 1970-01-01 (the time represented by the value
"<code title="">1970-01-01T00:00:00.0Z</code>").</p>
<p><strong>The <span
title="concept-input-value-string-date">algorithm to convert a
string to a <code>Date</code> object</span>, given a string <var
title="">input</var>, is as follows</strong>: If <span title="parse
a date string">parsing a date</span> from <var title="">input</var>
results in an error, then return an error; otherwise, return a
<code>Date</code> object representing midnight UTC on the morning of
the parsed <span title="concept-date">date</span>.</p>
<p><strong>The <span
title="concept-input-value-date-string">algorithm to convert a
<code>Date</code> object to a string</span>, given a
<code>Date</code> object <var title="">input</var>, is as
follows</strong>: Return a <span>valid date string</span> that
represents the <span title="concept-date">date</span> current at the
time represented by <var title="">input</var> in the UTC
time zone.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-step">step</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>,
<code title="dom-input-valueAsDate">valueAsDate</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes;
<code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>, and
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code> and
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-month">Month</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-month">Month</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
specific <span title="concept-month">month</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the <span
title="concept-month">month</span> represented by its <span
title="concept-fe-value">value</span>, as obtained by <span
title="parse a month string">parsing a month</span> from it. User
agents must not allow the user to set the <span
title="concept-fe-value">value</span> to a string that is not a
<span>valid month string</span>. If the user agent provides a user
interface for selecting a <span title="concept-month">month</span>,
then the <span title="concept-fe-value">value</span> must be set to
a <span>valid month string</span> representing the user's
selection. User agents should allow the user to set the <span
title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid month
string</span>.</p> <!-- ok to set out-of-range value, we never know
when we might have to represent bogus input -->
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is not a <span>valid month string</span>, then set it
to the empty string instead.</p>
</div>
<p>The <code title="attr-input-min">min</code> attribute, if
specified, must have a value that is a <span>valid month
string</span>. The <code title="attr-input-max">max</code>
attribute, if specified, must have a value that is a <span>valid
month string</span>.</p>
<p>The <code title="attr-input-step">step</code> attribute is
expressed in months. <span class="impl">The <span
title="concept-input-step-scale">step scale factor</span> is 1
(there is no conversion needed as the algorithms use months).</span>
The <span title="concept-input-step-default">default step</span> is
1 month.</p>
<div class="impl">
<p>When the element is <span>suffering from a step mismatch</span>,
the user agent may round the element's <span
title="concept-fe-value">value</span> to the nearest <span
title="concept-month">month</span> for which the element would not
<span title="suffering from a step mismatch">suffer from a step
mismatch</span>.</p>
<p><strong>The <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span>, given a string <var title="">input</var>,
is as follows</strong>: If <span title="parse a month
string">parsing a month</span> from <var title="">input</var>
results in an error, then return an error; otherwise, return the
number of months between January 1970 and the parsed <span
title="concept-month">month</span>.</p>
<p><strong>The <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, given a number <var title="">input</var>,
is as follows</strong>: Return a <span>valid month string</span>
that represents the <span title="concept-month">month</span> that
has <var title="">input</var> months between it and January
1970.</p>
<!-- note - it doesn't matter exactly how many months are "between"
two months, so long as the UA implements this consistently. The
number is never actually exposed. -->
<p><strong>The <span
title="concept-input-value-string-date">algorithm to convert a
string to a <code>Date</code> object</span>, given a string <var
title="">input</var>, is as follows</strong>: If <span title="parse
a month string">parsing a month</span> from <var
title="">input</var> results in an error, then return an error;
otherwise, return a <code>Date</code> object representing midnight
UTC on the morning of the first day of the parsed <span
title="concept-month">month</span>.</p>
<p><strong>The <span
title="concept-input-value-date-string">algorithm to convert a
<code>Date</code> object to a string</span>, given a
<code>Date</code> object <var title="">input</var>, is as
follows</strong>: Return a <span>valid month string</span> that
represents the <span title="concept-month">month</span> current at
the time represented by <var title="">input</var> in the UTC
time zone.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-step">step</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>,
<code title="dom-input-valueAsDate">valueAsDate</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes;
<code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>, and
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code> and
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-week">Week</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-week">Week</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
specific <span title="concept-week">week</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the <span
title="concept-week">week</span> represented by its <span
title="concept-fe-value">value</span>, as obtained by <span
title="parse a week string">parsing a week</span> from it. User
agents must not allow the user to set the <span
title="concept-fe-value">value</span> to a string that is not a
<span>valid week string</span>. If the user agent provides a user
interface for selecting a <span title="concept-week">week</span>,
then the <span title="concept-fe-value">value</span> must be set to
a <span>valid week string</span> representing the user's
selection. User agents should allow the user to set the <span
title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid week
string</span>.</p> <!-- ok to set out-of-range value, we never know
when we might have to represent bogus input -->
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is not a <span>valid week string</span>, then set it
to the empty string instead.</p>
</div>
<p>The <code title="attr-input-min">min</code> attribute, if
specified, must have a value that is a <span>valid week
string</span>. The <code title="attr-input-max">max</code>
attribute, if specified, must have a value that is a <span>valid
week string</span>.</p>
<p>The <code title="attr-input-step">step</code> attribute is
expressed in weeks. <span class="impl">The <span
title="concept-input-step-scale">step scale factor</span> is
604,800,000 (which converts the weeks to milliseconds, as used in
the other algorithms).</span> The <span
title="concept-input-step-default">default step</span> is 1
week.</p>
<div class="impl">
<p>When the element is <span>suffering from a step mismatch</span>,
the user agent may round the element's <span
title="concept-fe-value">value</span> to the nearest <span
title="concept-week">week</span> for which the element would not
<span title="suffering from a step mismatch">suffer from a step
mismatch</span>.</p>
<p><strong>The <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span>, given a string <var title="">input</var>,
is as follows</strong>: If <span title="parse a week string">parsing
a week string</span> from <var title="">input</var> results in an
error, then return an error; otherwise, return the number of
milliseconds elapsed from midnight UTC on the morning of 1970-01-01
(the time represented by the value "<code
title="">1970-01-01T00:00:00.0Z</code>") to midnight UTC on the
morning of the Monday of the parsed <span
title="concept-week">week</span>, ignoring leap seconds.</p>
<p><strong>The <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, given a number <var title="">input</var>,
is as follows</strong>: Return a <span>valid week string</span> that
represents the <span title="concept-week">week</span> that, in UTC,
is current <var title="">input</var> milliseconds after midnight UTC
on the morning of 1970-01-01 (the time represented by the value
"<code title="">1970-01-01T00:00:00.0Z</code>").</p>
<p><strong>The <span
title="concept-input-value-string-date">algorithm to convert a
string to a <code>Date</code> object</span>, given a string <var
title="">input</var>, is as follows</strong>: If <span title="parse
a week string">parsing a week</span> from <var title="">input</var>
results in an error, then return an error; otherwise, return a
<code>Date</code> object representing midnight UTC on the morning of
the Monday of the parsed <span title="concept-week">week</span>.</p>
<p><strong>The <span
title="concept-input-value-date-string">algorithm to convert a
<code>Date</code> object to a string</span>, given a
<code>Date</code> object <var title="">input</var>, is as
follows</strong>: Return a <span>valid week string</span> that
represents the <span title="concept-week">week</span> current at the
time represented by <var title="">input</var> in the UTC
time zone.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-step">step</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>,
<code title="dom-input-valueAsDate">valueAsDate</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes;
<code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>, and
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code> and
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-time">Time</dfn> state</h6>
<!-- v2: allow min="" and max="" to be set such that the range
crosses midnight, as in <input type=time min="23:00" max="02:00">
(from http://www.w3.org/Bugs/Public/show_bug.cgi?id=7688) -->
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-time">Time</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
specific <span title="concept-time">time</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the <span
title="concept-time">time</span> represented by its <span
title="concept-fe-value">value</span>, as obtained by <span
title="parse a time string">parsing a time</span> from it. User
agents must not allow the user to set the <span
title="concept-fe-value">value</span> to a string that is not a
<span>valid time string</span>. If the user agent provides a user
interface for selecting a <span title="concept-time">time</span>,
then the <span title="concept-fe-value">value</span> must be set to
a <span>valid time string</span> representing the user's
selection. User agents should allow the user to set the <span
title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid time
string</span>.</p> <!-- ok to set out-of-range value, we never know
when we might have to represent bogus input -->
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is not a <span>valid time string</span>, then set it
to the empty string instead.</p>
</div>
<p>The <code title="attr-input-min">min</code> attribute, if
specified, must have a value that is a <span>valid time
string</span>. The <code title="attr-input-max">max</code>
attribute, if specified, must have a value that is a <span>valid
time string</span>.</p>
<p>The <code title="attr-input-step">step</code> attribute is
expressed in seconds. <span class="impl">The <span
title="concept-input-step-scale">step scale factor</span> is 1000
(which converts the seconds to milliseconds, as used in the other
algorithms).</span> The <span
title="concept-input-step-default">default step</span> is 60
seconds.</p>
<div class="impl">
<p>When the element is <span>suffering from a step mismatch</span>,
the user agent may round the element's <span
title="concept-fe-value">value</span> to the nearest <span
title="concept-time">time</span> for which the element would not
<span title="suffering from a step mismatch">suffer from a step
mismatch</span>.</p>
<p><strong>The <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span>, given a string <var title="">input</var>,
is as follows</strong>: If <span title="parse a time string">parsing
a time</span> from <var title="">input</var> results in an error,
then return an error; otherwise, return the number of milliseconds
elapsed from midnight to the parsed <span
title="concept-time">time</span> on a day with no time changes.</p>
<p><strong>The <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, given a number <var title="">input</var>,
is as follows</strong>: Return a <span>valid time string</span> that
represents the <span title="concept-time">time</span> that is <var
title="">input</var> milliseconds after midnight on a day with no
time changes.</p>
<p><strong>The <span
title="concept-input-value-string-date">algorithm to convert a
string to a <code>Date</code> object</span>, given a string <var
title="">input</var>, is as follows</strong>: If <span title="parse
a time string">parsing a time</span> from <var title="">input</var>
results in an error, then return an error; otherwise, return a
<code>Date</code> object representing the parsed <span
title="concept-time">time</span> in UTC on 1970-01-01.</p>
<p><strong>The <span
title="concept-input-value-date-string">algorithm to convert a
<code>Date</code> object to a string</span>, given a
<code>Date</code> object <var title="">input</var>, is as
follows</strong>: Return a <span>valid time string</span> that
represents the UTC <span title="concept-time">time</span> component
that is represented by <var title="">input</var>.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-step">step</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>,
<code title="dom-input-valueAsDate">valueAsDate</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes;
<code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>, and
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code> and
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-datetime-local">Local Date and Time</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-datetime-local">Local Date and Time</span>
state, the rules in this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
<span title="concept-datetime-local">local date and time</span>,
with no time-zone offset information.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the <span
title="concept-datetime-local">date and time</span> represented by
its <span title="concept-fe-value">value</span>, as obtained by
<span title="parse a local date and time string">parsing a date and
time</span> from it. User agents must not allow the user to set the
<span title="concept-fe-value">value</span> to a string that is not
a <span>valid local date and time string</span>. If the user agent
provides a user interface for selecting a <span
title="concept-datetime-local">local date and time</span>, then the
<span title="concept-fe-value">value</span> must be set to a
<span>valid local date and time string</span> representing the
user's selection. User agents should allow the user to set the <span
title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid local date and
time string</span>.</p> <!-- ok to set out-of-range value, we never
know when we might have to represent bogus input -->
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is not a <span>valid local date and time
string</span>, then set it to the empty string instead.</p>
</div>
<p>The <code title="attr-input-min">min</code> attribute, if
specified, must have a value that is a <span>valid local date and
time string</span>. The <code title="attr-input-max">max</code>
attribute, if specified, must have a value that is a <span>valid
local date and time string</span>.</p>
<p>The <code title="attr-input-step">step</code> attribute is
expressed in seconds. <span class="impl">The <span
title="concept-input-step-scale">step scale factor</span> is 1000
(which converts the seconds to milliseconds, as used in the other
algorithms).</span> The <span
title="concept-input-step-default">default step</span> is 60
seconds.</p>
<div class="impl">
<p>When the element is <span>suffering from a step mismatch</span>,
the user agent may round the element's <span
title="concept-fe-value">value</span> to the nearest <span
title="concept-datetime-local">local date and time</span> for which
the element would not <span title="suffering from a step
mismatch">suffer from a step mismatch</span>.</p>
<p><strong>The <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span>, given a string <var title="">input</var>,
is as follows</strong>: If <span title="parse a local date and time
string">parsing a date and time</span> from <var
title="">input</var> results in an error, then return an error;
otherwise, return the number of milliseconds elapsed from midnight
on the morning of 1970-01-01 (the time represented by the value
"<code title="">1970-01-01T00:00:00.0</code>") to the parsed <span
title="concept-datetime-local">local date and time</span>, ignoring
leap seconds.</p>
<p><strong>The <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, given a number <var title="">input</var>,
is as follows</strong>: Return a <span>valid local date and time
string</span> that represents the date and time that is <var
title="">input</var> milliseconds after midnight on the morning of
1970-01-01 (the time represented by the value "<code
title="">1970-01-01T00:00:00.0</code>").</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-step">step</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes;
<code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>, and
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code> and
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
</div>
<div class="example">
<p>The following example shows part of a flight booking
application. The application uses an <code>input</code> element
with its <code title="attr-input-type">type</code> attribute set to
<code title="attr-input-type-datetime-local">datetime-local</code>,
and it then interprets the given date and time in the time zone of
the selected airport.</p>
<pre><fieldset>
<legend>Destination</legend>
<p><label>Airport: <input type=text name=to list=airports></label></p>
<p><label>Departure time: <input type=datetime-local name=totime step=3600></label></p>
</fieldset>
<datalist id=airports>
<option value=ATL label="Atlanta">
<option value=MEM label="Memphis">
<option value=LHR label="London Heathrow">
<option value=LAX label="Los Angeles">
<option value=FRA label="Frankfurt">
</datalist></pre>
<p>If the application instead used the <code
title="attr-input-type-datetime">datetime</code> type, then the
user would have to work out the time-zone conversions himself,
which is clearly not a good user experience!</p>
</div>
<h6><dfn title="attr-input-type-number">Number</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-number">Number</span> state, the rules in
this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
number.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the number
represented by its <span title="concept-fe-value">value</span>, as
obtained from applying the <span>rules for parsing floating point
number values</span> to it. User agents must not allow the user to
set the <span title="concept-fe-value">value</span> to a string that
is not a <span>valid floating point number</span>. If the user agent
provides a user interface for selecting a number, then the <span
title="concept-fe-value">value</span> must be set to the <span
title="best representation of the number as a floating point
number">best representation of the number representing the user's
selection as a floating point number</span>. User agents should
allow the user to set the <span
title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid floating point
number</span>.</p> <!-- ok to set out-of-range value, we never know
when we might have to represent bogus input -->
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is not a <span>valid floating point number</span>,
then set it to the empty string instead.</p>
</div>
<p>The <code title="attr-input-min">min</code> attribute, if
specified, must have a value that is a <span>valid floating point
number</span>. The <code title="attr-input-max">max</code>
attribute, if specified, must have a value that is a <span>valid
floating point number</span>.</p>
<p><span class="impl">The <span
title="concept-input-step-scale">step scale factor</span> is
1.</span> The <span title="concept-input-step-default">default
step</span> is 1 (allowing only integers, unless the <code
title="attr-input-min">min</code> attribute has a non-integer
value).</p>
<div class="impl">
<p>When the element is <span>suffering from a step mismatch</span>,
the user agent may round the element's <span
title="concept-fe-value">value</span> to the nearest number for
which the element would not <span title="suffering from a step
mismatch">suffer from a step mismatch</span>.</p>
<p><strong>The <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span>, given a string <var title="">input</var>,
is as follows</strong>: If applying the <span>rules for parsing
floating point number values</span> to <var title="">input</var>
results in an error, then return an error; otherwise, return the
resulting number.</p>
<p><strong>The <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, given a number <var title="">input</var>,
is as follows</strong>: Return a <span>valid floating point
number</span> that represents <var title="">input</var>.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>,
<code title="attr-input-readonly">readonly</code>,
<code title="attr-input-required">required</code>, and
<code title="attr-input-step">step</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes;
<code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>, and
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code> and
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-range">Range</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-range">Range</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
number, but with the caveat that the exact value is not important,
letting UAs provide a simpler interface than they do for the <span
title="attr-input-type-number">Number</span> state.</p>
<div class="impl">
<p class="note">In this state, the range and step constraints are
enforced even during user input, and there is no way to set the
value to the empty string.</p>
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the number
represented by its <span title="concept-fe-value">value</span>, as
obtained from applying the <span>rules for parsing floating point
number values</span> to it. User agents must not allow the user to
set the <span title="concept-fe-value">value</span> to a string that
is not a <span>valid floating point number</span>. If the user agent
provides a user interface for selecting a number, then the <span
title="concept-fe-value">value</span> must be set to a <span
title="best representation of the number as a floating point
number">best representation of the number representing the user's
selection as a floating point number</span>. User agents must not
allow the user to set the <span
title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid floating point
number</span>.</p> <!-- ok to set out-of-range value, we never know
when we might have to represent bogus input -->
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is not a <span>valid floating point number</span>,
then set it to a <span>valid floating point number</span> that
represents the <span
title="concept-input-value-default-range">default value</span>.</p>
</div>
<p>The <code title="attr-input-min">min</code> attribute, if
specified, must have a value that is a <span>valid floating point
number</span>. The <span title="concept-input-min-default">default
minimum</span> is 0. The <code title="attr-input-max">max</code>
attribute, if specified, must have a value that is a <span>valid
floating point number</span>. The <span
title="concept-input-max-default">default maximum</span> is 100.</p>
<p>The <dfn title="concept-input-value-default-range">default
value</dfn> is the <span title="concept-input-min">minimum</span>
plus half the difference between the <span
title="concept-input-min">minimum</span> and the <span
title="concept-input-max">maximum</span>, unless the <span
title="concept-input-max">maximum</span> is less than the <span
title="concept-input-min">minimum</span>, in which case the <span
title="concept-input-value-default-range">default value</span> is
the <span title="concept-input-min">minimum</span>.</p>
<div class="impl">
<p>When the element is <span>suffering from an
underflow</span>, the user agent must set the element's <span
title="concept-fe-value">value</span> to a <span>valid floating point
number</span> that represents the <span
title="concept-input-min">minimum</span>.</p>
<p>When the element is <span>suffering from an overflow</span>,
if the <span title="concept-input-max">maximum</span> is not less
than the <span title="concept-input-min">minimum</span>, the user
agent must set the element's <span
title="concept-fe-value">value</span> to a <span>valid floating point
number</span> that represents the <span
title="concept-input-max">maximum</span>.</p>
</div>
<p><span class="impl">The <span
title="concept-input-step-scale">step scale factor</span> is
1.</span> The <span title="concept-input-step-default">default
step</span> is 1 (allowing only integers, unless the <code
title="attr-input-min">min</code> attribute has a non-integer
value).</p>
<div class="impl">
<p>When the element is <span>suffering from a step mismatch</span>,
the user agent must round the element's <span
title="concept-fe-value">value</span> to the nearest number for
which the element would not <span title="suffering from a step
mismatch">suffer from a step mismatch</span>, and which is greater
than or equal to the <span title="concept-input-min">minimum</span>,
and, if the <span title="concept-input-max">maximum</span> is not
less than the <span title="concept-input-min">minimum</span>, which
is less than or equal to the <span
title="concept-input-max">maximum</span>.</p>
<p><strong>The <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span>, given a string <var title="">input</var>,
is as follows</strong>: If applying the <span>rules for parsing
floating point number values</span> to <var title="">input</var>
results in an error, then return an error; otherwise, return the
resulting number.</p>
<p><strong>The <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, given a number <var title="">input</var>,
is as follows</strong>: Return a <span>valid floating point
number</span> that represents <var title="">input</var>.</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code>,
<code title="attr-input-list">list</code>,
<code title="attr-input-max">max</code>,
<code title="attr-input-min">min</code>, and
<code title="attr-input-step">step</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>,
<code title="dom-input-valueAsNumber">valueAsNumber</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes;
<code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-required">required</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>, and
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code> and
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-color">Color</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-color">Color</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a color
well control, for setting the element's <span
title="concept-fe-value">value</span> to a string representing a
<span>simple color</span>.</p>
<div class="impl">
<p class="note">In this state, there is always a color picked, and
there is no way to set the value to the empty string.</p>
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the color represented
by its <span title="concept-fe-value">value</span>, as obtained from
applying the <span>rules for parsing simple color values</span> to
it. User agents must not allow the user to set the <span
title="concept-fe-value">value</span> to a string that is not a
<span>valid lowercase simple color</span>. If the user agent
provides a user interface for selecting a color, then the <span
title="concept-fe-value">value</span> must be set to the result of
using the <span>rules for serializing simple color values</span> to
the user's selection. User agents must not allow the user to set the
<span title="concept-fe-value">value</span> to the empty string.</p>
</div>
<p>The <code title="attr-input-value">value</code> attribute, if
specified, must have a value that is a <span>valid simple
color</span>.</p>
<div class="impl">
<p><strong>The <span>value sanitization algorithm</span> is as
follows</strong>: If the <span title="concept-fe-value">value</span>
of the element is a <span>valid simple color</span>, then set it to
the <span title="concept-fe-value">value</span> of the element
<span>converted to ASCII lowercase</span>; otherwise, set it to the string
"<code title="">#000000</code>".</p>
</div>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes, IDL attributes, and methods apply to the element:
<code title="attr-input-autocomplete">autocomplete</code> and
<code title="attr-input-list">list</code> content attributes;
<code title="dom-input-list">list</code>,
<code title="dom-input-value">value</code>, and
<code title="dom-input-selectedOption">selectedOption</code> IDL attributes.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-value">value</span>.</p>
<p>The <code title="event-input-input">input</code> and <code
title="event-input-change">change</code> events apply.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-required">required</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
</div>
<h6><dfn title="attr-input-type-checkbox">Checkbox</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-checkbox">Checkbox</span> state, the rules in
this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a
two-state control that represents the element's <span
title="concept-fe-checked">checkedness</span> state. If the
element's <span title="concept-fe-checked">checkedness</span> state
is true, the control represents a positive selection, and if it is
false, a negative selection. If the element's <code
title="dom-input-indeterminate">indeterminate</code> IDL attribute
is set to true, then the control's selection should be obscured as
if the control was in a third, indeterminate, state.</p>
<p class="note">The control is never a true tri-state control, even
if the element's <code
title="dom-input-indeterminate">indeterminate</code> IDL attribute
is set to true. The <code
title="dom-input-indeterminate">indeterminate</code> IDL attribute
only gives the appearance of a third state.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
then: The <span>pre-click activation steps</span> consist of setting
the element's <span title="concept-fe-checked">checkedness</span> to
its opposite value (i.e. true if it is false, false if it is true),
and of setting the element's <code
title="dom-input-indeterminate">indeterminate</code> IDL attribute
to false. The <span>canceled activation steps</span> consist of
setting the <span title="concept-fe-checked">checkedness</span> and
the element's <code
title="dom-input-indeterminate">indeterminate</code> IDL attribute
back to the values they had before the <span>pre-click activation
steps</span> were run. The <span>activation behavior</span> is to
<span>fire a simple event</span> that bubbles named <code
title="event-change">change</code> at the element<!-- It's not
cancelable. Once this fires, the control is checked, end of
story. -->, then <span>broadcast <code
title="event-formchange">formchange</code> events</span> at the
element's <span>form owner</span>.</p>
<p><strong>Constraint validation</strong>: If the element is <i
title="concept-input-required">required</i> and its <span
title="concept-fe-checked">checkedness</span> is false, then the
element is <span>suffering from being missing</span>.</p>
</div>
<dl class="domintro">
<dt><var title="">input</var> . <code title="dom-input-indeterminate">indeterminate</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>When set, overrides the rendering of <span
title="attr-input-type-checkbox">checkbox</span> controls so that
the current value is not visible.</p>
</dd>
</dl>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes and IDL attributes apply to the element:
<code title="attr-input-checked">checked</code>, and
<code title="attr-input-required">required</code> content attributes;
<code title="dom-input-checked">checked</code> and
<code title="dom-input-value">value</code> IDL attributes.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-default-on">default/on</span>.</p>
<p>The <code title="event-input-change">change</code> event applies.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-autocomplete">autocomplete</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code class="no-backref"
title="event-input-input">input</code> event does not apply.</p>
</div>
<h6><dfn title="attr-input-type-radio">Radio Button</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-radio">Radio Button</span> state, the rules
in this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a control
that, when used in conjunction with other <code>input</code>
elements, forms a <i>radio button group</i> in which only one
control can have its <span
title="concept-fe-checked">checkedness</span> state set to true. If
the element's <span title="concept-fe-checked">checkedness</span>
state is true, the control represents the selected control in the
group, and if it is false, it indicates a control in the group that
is not selected.</p>
<p>The <dfn><i>radio button group</i></dfn> that contains an
<code>input</code> element <var title="">a</var> also contains all
the other <code>input</code> elements <var title="">b</var> that
fulfill all of the following conditions:</p>
<ul>
<li>The <code>input</code> element <var title="">b</var>'s <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-radio">Radio Button</span> state.</li>
<li>Either <var title="">a</var> and <var title="">b</var> have the
same <span>form owner</span>, or they both have no <span>form
owner</span>.</li>
<li>They both have a <code title="attr-fe-name">name</code>
attribute, and the value of <var title="">a</var>'s <code
title="attr-fe-name">name</code> attribute is a
<span>compatibility caseless</span> match for the value of <var
title="">b</var>'s <code title="attr-fe-name">name</code>
attribute.</li>
</ul>
<p>A document must not contain an <code>input</code> element whose
<i>radio button group</i> contains only that element.</p>
<div class="impl">
<p>When any of the following events occur, if the element's <span
title="concept-fe-checked">checkedness</span> state is true after
the event, the <span
title="concept-fe-checked">checkedness</span> state of all the
other elements in the same <i>radio button group</i> must be set to
false:</p>
<ul>
<li>The element's <span
title="concept-fe-checked">checkedness</span> state is set to
true (for whatever reason).</li>
<li>The element's <code title="attr-fe-name">name</code>
attribute is added, removed, or changes value.</li>
<li>The element's <span>form owner</span> changes.</li>
</ul>
<p>If the element is <i title="concept-input-mutable">mutable</i>,
then: The <span>pre-click activation steps</span> consist of setting
the element's <span title="concept-fe-checked">checkedness</span> to
true. The <span>canceled activation steps</span> consist of setting
the element's <span title="concept-fe-checked">checkedness</span> to
false. The <span>activation behavior</span> is to <span>fire a
simple event</span> that bubbles named <code
title="event-change">change</code> at the element<!-- It's not
cancelable. Once this fires, the control is checked, end of
story. -->, then <span>broadcast <code
title="event-formchange">formchange</code> events</span> at the
element's <span>form owner</span>.</p>
<p><strong>Constraint validation</strong>: If the element is <i
title="concept-input-required">required</i> and all of the
<code>input</code> elements in the <i>radio button group</i> have a
<span title="concept-fe-checked">checkedness</span> that is
false, then the element is <span>suffering from being
missing</span>.</p>
</div>
<p class="note">If none of the radio buttons in a <span>radio button
group</span> are checked when they are inserted into the document,
then they will all be initially unchecked in the interface, until
such time as one of them is checked (either by the user or by
script).</p>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes and IDL attributes apply to the element:
<code title="attr-input-checked">checked</code> and
<code title="attr-input-required">required</code> content attributes;
<code title="dom-input-checked">checked</code> and
<code title="dom-input-value">value</code> IDL attributes.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-default-on">default/on</span>.</p>
<p>The <code title="event-input-change">change</code> event applies.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-autocomplete">autocomplete</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code class="no-backref"
title="event-input-input">input</code> event does not apply.</p>
</div>
<h6><dfn title="attr-input-type-file">File Upload</dfn> state</h6>
<!-- v2 ideas:
* maximum height/width or required ratio for image uploads? - Leons Petrazickis
* maximum per-file upload size - Alfonso Martínez de Lizarrondo
-->
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-file">File Upload</span> state, the rules in this
section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a list of
<dfn title="concept-input-type-file-selected">selected files</dfn>,
each file consisting of a file name, a file type, and a file body
(the contents of the file).</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to change the files on the
list, e.g. adding or removing files. Files can be from the
filesystem or created on the fly, e.g. a picture taken from a camera
connected to the user's device.</p>
<p><strong>Constraint validation</strong>: If the element is <i
title="concept-input-required">required</i> and the list of <span
title="concept-input-type-file-selected">selected files</span> is
empty, then the element is <span>suffering from being
missing</span>.</p>
<p>Unless the <code title="attr-input-multiple">multiple</code>
attribute is set, there must be no more than one file in the list of
<span title="concept-input-type-file-selected">selected
files</span>.</p>
</div>
<hr>
<p>The <dfn title="attr-input-accept"><code>accept</code></dfn>
attribute may be specified to provide user agents with a hint of
what file types the server will be able to accept.</p>
<p>If specified, the attribute must consist of a <span>set of
comma-separated tokens</span>, each of which must be an <span>ASCII
case-insensitive</span> match for one of the following:</p>
<dl>
<dt>The string <code title="">audio/*</code></dt>
<dd>Indicates that sound files are accepted.</dd>
<dt>The string <code title="">video/*</code></dt>
<dd>Indicates that video files are accepted.</dd>
<dt>The string <code title="">image/*</code></dt>
<dd>Indicates that image files are accepted.</dd>
<dt>A <span>valid MIME type</span>, with no parameters</dt>
<dd>Indicates that files of the specified type are accepted.</dd>
</dl>
<p>The tokens must not be <span>ASCII case-insensitive</span>
matches for any of the other tokens (i.e. duplicates are not
allowed). <span class="impl">To obtain the list of tokens from the
attribute, the user agent must <span title="split a string on
commas">split the attribute value on commas</span>.</span></p>
<div class="impl">
<p>User agents should prevent the user from selecting files that are
not accepted by one (or more) of these tokens.</p>
</div>
<div class="example">
<p>For historical reasons, the <code
title="dom-input-value">value</code> IDL attribute prefixes the
filename with the string "<code title="">C:\fakepath\</code>". Some
legacy user agents actually included the full path (which was a
security vulnerability). As a result of this, obtaining the
filename from the <code title="dom-input-value">value</code> IDL
attribute in a backwards-compatible way is non-trivial. The
following function extracts the filename in a suitably compatible
manner:</p>
<pre>function extractFilename(path) {<!--
if (path.substr(0, 12) == "C:\\fakepath\\")
return path.substr(12);-->
var x;
x = path.lastIndexOf('\\');
if (x >= 0) // Windows-based path
return path.substr(x+1);
x = path.lastIndexOf('/');
if (x >= 0) // Unix-based path
return path.substr(x+1);
return path; // just the filename
}</pre>
<p>This can be used as follows:</p>
<pre><p><input type=file name=image onchange="updateFilename(this.value)"></p>
<p>The name of the file you picked is: <span id="filename">(none)</span></p>
<script>
function updateFilename(path) {
var name = extractFilename(path);
document.getElementById('filename').textContent = name;
}
</script></pre>
<!-- How useful this actually is... is unclear. -->
</div>
<hr>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes apply to the element:
<p>The following common <code>input</code> element content
attributes and IDL attributes apply to the element:
<code title="attr-input-accept">accept</code>,
<code title="attr-input-multiple">multiple</code>, and
<code title="attr-input-required">required</code>;
<code title="dom-input-files">files</code> and
<code title="dom-input-value">value</code> IDL attributes.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-filename">filename</span>.</p>
<p>The <code title="event-input-change">change</code> event applies.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-autocomplete">autocomplete</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The element's <code title="attr-input-value">value</code>
attribute must be omitted.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code class="no-backref"
title="event-input-input">input</code> event does not apply.</p>
</div>
<h6><dfn title="attr-input-type-submit">Submit Button</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-submit">Submit Button</span> state, the rules
in this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a button
that, when activated, submits the form. <span class="impl">If the
element has a <code title="attr-input-value">value</code> attribute,
the button's label must be the value of that attribute; otherwise,
it must be an implementation-defined string that means "Submit" or
some such.</span> The element is a <span
title="concept-button">button</span>, specifically a <span
title="concept-submit-button">submit button</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to activate the element.</p>
<p>The element's <span>activation behavior</span>, if the element
has a <span>form owner</span>, is to <span
title="concept-form-submit">submit</span> the <span>form
owner</span> from the <code>input</code> element; otherwise, it is
to do nothing.</p>
</div>
<p>The <code title="attr-fs-formaction">formaction</code>, <code
title="attr-fs-formenctype">formenctype</code>, <code
title="attr-fs-formmethod">formmethod</code>, <code
title="attr-fs-formnovalidate">formnovalidate</code>, and <code
title="attr-fs-formtarget">formtarget</code> attributes are <span>attributes
for form submission</span>.</p>
<p class="note">The <code
title="attr-fs-formnovalidate">formnovalidate</code> attribute can
be used to make submit buttons that do not trigger the constraint
validation.</p>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes and IDL attributes apply to the element:
<code title="attr-fs-formaction">formaction</code>,
<code title="attr-fs-formenctype">formenctype</code>,
<code title="attr-fs-formmethod">formmethod</code>,
<code title="attr-fs-formnovalidate">formnovalidate</code>, and
<code title="attr-fs-formtarget">formtarget</code> content attributes;
<code title="dom-input-value">value</code> IDL attribute.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-default">default</span>.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-autocomplete">autocomplete</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-required">required</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code class="no-backref"
title="event-input-input">input</code> and <code class="no-backref"
title="event-input-change">change</code> events do not apply.</p>
</div>
<h6><dfn title="attr-input-type-image">Image Button</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-image">Image Button</span> state, the rules
in this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> either an
image from which a user can select a coordinate and submit the form,
or alternatively a button from which the user can submit the
form. The element is a <span title="concept-button">button</span>,
specifically a <span title="concept-submit-button">submit
button</span>.</p>
<hr>
<p>The image is given by the <dfn
title="attr-input-src"><code>src</code></dfn> attribute. The <code
title="attr-input-src">src</code> attribute must be present, and
must contain a <span>valid URL</span> referencing a non-interactive,
optionally animated, image resource that is neither paged nor
scripted.</p>
<div class="impl">
<p>When any of the following events occur, unless the user agent
cannot support images, or its support for images has been disabled,
or the user agent only fetches elements on demand, the user agent
must <span title="resolve a url">resolve</span> the value of the
<code title="attr-input-src">src</code> attribute, relative to the
element, and if that is successful, must <span>fetch</span> the
resulting <span>absolute URL</span>:</p> <!-- Note how this does NOT
happen when the base URL changes. --> <!-- http-origin privacy
sensitive -->
<ul>
<li>The <code>input</code> element's <code
title="attr-input-type">type</code> attribute is first set to the
<span title="attr-input-type-image">Image Button</span> state
(possibly when the element is first created), and the <code
title="attr-input-src">src</code> attribute is present.</li>
<li>The <code>input</code> element's <code
title="attr-input-type">type</code> attribute is changed back to
the <span title="attr-input-type-image">Image Button</span> state,
and the <code title="attr-input-src">src</code> attribute is
present, and its value has changed since the last time the <code
title="attr-input-type">type</code> attribute was in the <span
title="attr-input-type-image">Image Button</span> state.</li>
<li>The <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-image">Image Button</span> state, and the
<code title="attr-input-src">src</code> attribute is set or
changed.</li>
</ul>
<!-- same text in <img> section and similar text elsewhere -->
<p>Fetching the image must <span>delay the load event</span> of the
element's document until the <span title="concept-task">task</span>
that is <span title="queue a task">queued</span> by the
<span>networking task source</span> once the resource has been <span
title="fetch">fetched</span> (defined below) has been run.</p>
<p>If the image was successfully obtained, with no network errors,
and the image's type is a supported image type, and the image is a
valid image of that type, then the image is said to be <dfn
title="input-img-available"><i>available</i></dfn>. If this is true
before the image is completely downloaded, each <span
title="concept-task">task</span> that is <span title="queue a
task">queued</span> by the <span>networking task source</span> while
the image is being <span title="fetch">fetched</span> must update
the presentation of the image appropriately.</p>
<p>The user agents should apply the <span title="Content-Type
sniffing: image">image sniffing rules</span> to determine the type
of the image, with the image's <span title="Content-Type">associated
Content-Type headers</span> giving the <var title="">official
type</var>. If these rules are not applied, then the type of the
image must be the type given by the image's <span
title="Content-Type">associated Content-Type headers</span>.</p>
<p>User agents must not support non-image resources with the
<code>input</code> element. User agents must not run executable code
embedded in the image resource. User agents must only display the
first page of a multipage resource. User agents must not allow the
resource to act in an interactive fashion, but should honor any
animation in the resource.</p>
<p>The <span title="concept-task">task</span> that is <span
title="queue a task">queued</span> by the <span>networking task
source</span> once the resource has been <span
title="fetch">fetched</span>, must, if the download was successful
and the image is <i title="input-img-available">available</i>,
<span>queue a task</span> to <span>fire a simple event</span> named
<code title="event-load">load</code> at the <code>input</code>
element; and otherwise, if the fetching process fails without a
response from the remote server, or completes but the image is not a
valid or supported image, <span>queue a task</span> to <span>fire a
simple event</span> named <code title="event-error">error</code> on
the <code>input</code> element.</p>
<hr>
</div>
<p>The <dfn title="attr-input-alt"><code>alt</code></dfn> attribute
provides the textual label for the alternative button for users and
user agents who cannot use the image. The <code
title="attr-input-alt">alt</code> attribute must also be present,
and must contain a non-empty string.</p>
<p>The <code>input</code> element supports <span>dimension
attributes</span>.</p>
<div class="impl">
<hr>
<p>If the <code title="attr-input-src">src</code> attribute is set,
and the image is <i title="input-img-available">available</i> and
the user agent is configured to display that image, then: The
element <span>represents</span> a control for selecting a <span
title="concept-input-type-image-coordinate">coordinate</span> from
the image specified by the <code title="attr-input-src">src</code>
attribute; if the element is <i
title="concept-input-mutable">mutable</i>, the user agent should
allow the user to select this <span
title="concept-input-type-image-coordinate">coordinate</span>. The
<span>activation behavior</span> in this case consists of taking the
user's selected <span
title="concept-input-type-image-coordinate">coordinate</span>, and
then, if the element has a <span>form owner</span>, <span
title="concept-form-submit">submitting</span> the <code>input</code>
element's <span>form owner</span> from the <code>input</code>
element. If the user activates the control without explicitly
selecting a coordinate, then the coordinate (0,0) must be
assumed.</p>
<p>Otherwise, the element <span>represents</span> a submit button
whose label is given by the value of the <code
title="attr-input-alt">alt</code> attribute; if the element is <i
title="concept-input-mutable">mutable</i>, the user agent should
allow the user to activate the button. The <span>activation
behavior</span> in this case consists of setting the <span
title="concept-input-type-image-coordinate">selected
coordinate</span> to (0,0), and then, if the element has a
<span>form owner</span>, <span
title="concept-form-submit">submitting</span> the <code>input</code>
element's <span>form owner</span> from the <code>input</code>
element.</p>
<p>The <dfn title="concept-input-type-image-coordinate">selected
coordinate</dfn> must consist of an <var title="">x</var>-component
and a <var title="">y</var>-component. The <var
title="">x</var>-component must be greater than or equal to zero,
and less than or equal to the rendered width, in CSS pixels, of the
image, plus the widths of the left and right borders rendered around
the image, if any. The <var title="">y</var>-component must be
greater than or equal to zero, and less than or equal to the
rendered height, in CSS pixels, of the image, plus the widths of the
top and bottom bordered rendered around the image, if any. The
coordinates must be relative to the image's borders, where there are
any, and the edge of the image otherwise.</p> <!-- legacy browser
behavior sometimes does some sure wacky things. -->
<hr>
</div>
<p>The <code title="attr-fs-formaction">formaction</code>, <code
title="attr-fs-formenctype">formenctype</code>, <code
title="attr-fs-formmethod">formmethod</code>, <code
title="attr-fs-formnovalidate">formnovalidate</code>, and <code
title="attr-fs-formtarget">formtarget</code> attributes are <span>attributes
for form submission</span>.</p>
<div class="bookkeeping">
<p>The following common <code>input</code> element content
attributes and IDL attributes apply to the element:
<code title="attr-input-alt">alt</code>,
<code title="attr-fs-formaction">formaction</code>,
<code title="attr-fs-formenctype">formenctype</code>,
<code title="attr-fs-formmethod">formmethod</code>,
<code title="attr-fs-formnovalidate">formnovalidate</code>,
<code title="attr-fs-formtarget">formtarget</code>,
<code title="attr-dim-height">height</code>,
<code title="attr-input-src">src</code>, and
<code title="attr-dim-width">width</code> content attributes;
<code title="dom-input-value">value</code> IDL attribute.</p>
<p>The <code title="dom-input-value">value</code> IDL attribute is
in mode <span title="dom-input-value-default">default</span>.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-autocomplete">autocomplete</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-required">required</code>,
<code class="no-backref" title="attr-input-size">size</code>, and
<code class="no-backref" title="attr-input-step">step</code>.</p>
<p>The element's <code title="attr-input-value">value</code>
attribute must be omitted.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code class="no-backref"
title="event-input-input">input</code> and <code class="no-backref"
title="event-input-change">change</code> events do not apply.</p>
</div>
<p class="note">Many aspects of this state's behavior are similar to
the behavior of the <code>img</code> element. Readers are encouraged
to read that section, where many of the same requirements are
described in more detail.</p>
<h6><dfn title="attr-input-type-reset">Reset Button</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-reset">Reset Button</span> state, the rules
in this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a button
that, when activated, resets the form. <span class="impl">If the
element has a <code title="attr-input-value">value</code> attribute,
the button's label must be the value of that attribute; otherwise,
it must be an implementation-defined string that means "Reset" or
some such.</span> The element is a <span
title="concept-button">button</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to activate the element.</p>
<p>The element's <span>activation behavior</span>, if the element
has a <span>form owner</span>, is to <span
title="concept-form-reset">reset</span> the <span>form owner</span>;
otherwise, it is to do nothing.</p>
<p><strong>Constraint validation</strong>: The element is
<span>barred from constraint validation</span>.</p>
</div>
<div class="bookkeeping">
<p>The <code title="dom-input-value">value</code> IDL attribute
applies to this element and is in mode <span
title="dom-input-value-default">default</span>.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-autocomplete">autocomplete</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-required">required</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code class="no-backref"
title="event-input-input">input</code> and <code class="no-backref"
title="event-input-change">change</code> events do not apply.</p>
</div>
<h6><dfn title="attr-input-type-button">Button</dfn> state</h6>
<div class="impl">
<p>When an <code>input</code> element's <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-button">Button</span> state, the rules in
this section apply.</p>
</div>
<p>The <code>input</code> element <span>represents</span> a button
with no default behavior. <span class="impl">If the element has a
<code title="attr-input-value">value</code> attribute, the button's
label must be the value of that attribute; otherwise, it must be the
empty string.</span> The element is a <span
title="concept-button">button</span>.</p>
<div class="impl">
<p>If the element is <i title="concept-input-mutable">mutable</i>,
the user agent should allow the user to activate the element. The
element's <span>activation behavior</span> is to do nothing.</p>
<p><strong>Constraint validation</strong>: The element is
<span>barred from constraint validation</span>.</p>
</div>
<div class="bookkeeping">
<p>The <code title="dom-input-value">value</code> IDL attribute
applies to this element and is in mode <span
title="dom-input-value-default">default</span>.</p>
<p>The following content attributes must not be specified and do not
apply to the element:
<code class="no-backref" title="attr-input-accept">accept</code>,
<code class="no-backref" title="attr-input-alt">alt</code>,
<code class="no-backref" title="attr-input-autocomplete">autocomplete</code>,
<code class="no-backref" title="attr-input-checked">checked</code>,
<code class="no-backref" title="attr-fs-formaction">formaction</code>,
<code class="no-backref" title="attr-fs-formenctype">formenctype</code>,
<code class="no-backref" title="attr-fs-formmethod">formmethod</code>,
<code class="no-backref" title="attr-fs-formnovalidate">formnovalidate</code>,
<code class="no-backref" title="attr-fs-formtarget">formtarget</code>,
<code class="no-backref" title="attr-dim-height">height</code>,
<code class="no-backref" title="attr-input-list">list</code>,
<code class="no-backref" title="attr-input-max">max</code>,
<code class="no-backref" title="attr-input-maxlength">maxlength</code>,
<code class="no-backref" title="attr-input-min">min</code>,
<code class="no-backref" title="attr-input-multiple">multiple</code>,
<code class="no-backref" title="attr-input-pattern">pattern</code>,
<code class="no-backref" title="attr-input-placeholder">placeholder</code>,
<code class="no-backref" title="attr-input-readonly">readonly</code>,
<code class="no-backref" title="attr-input-required">required</code>,
<code class="no-backref" title="attr-input-size">size</code>,
<code class="no-backref" title="attr-input-src">src</code>,
<code class="no-backref" title="attr-input-step">step</code>, and
<code class="no-backref" title="attr-dim-width">width</code>.</p>
<p>The following IDL attributes and methods do not apply to the
element:
<code class="no-backref" title="dom-input-checked">checked</code>,
<code class="no-backref" title="dom-input-files">files</code>,
<code class="no-backref" title="dom-input-list">list</code>,
<code class="no-backref" title="dom-input-selectedOption">selectedOption</code>,
<code class="no-backref" title="dom-textarea/input-selectionStart">selectionStart</code>,
<code class="no-backref" title="dom-textarea/input-selectionEnd">selectionEnd</code>,
<code class="no-backref" title="dom-input-valueAsDate">valueAsDate</code>, and
<code class="no-backref" title="dom-input-valueAsNumber">valueAsNumber</code> IDL attributes;
<code class="no-backref" title="dom-textarea/input-select">select()</code>,
<code class="no-backref" title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>,
<code class="no-backref" title="dom-input-stepDown">stepDown()</code>, and
<code class="no-backref" title="dom-input-stepUp">stepUp()</code> methods.</p>
<p>The <code class="no-backref"
title="event-input-input">input</code> and <code class="no-backref"
title="event-input-change">change</code> events do not apply.</p>
</div>
<h5>Common <code>input</code> element attributes</h5>
<div class="impl">
<p>These attributes only apply to an <code>input</code> element if
its <code title="attr-input-type">type</code> attribute is in a
state whose definition declares that the attribute applies. When an
attribute doesn't apply to an <code>input</code> element, user
agents must <span>ignore</span> the attribute, regardless of the
requirements and definitions below.</p>
</div>
<h6>The <code title="attr-input-autocomplete">autocomplete</code> attribute</h6>
<p>User agents sometimes have features for helping users fill forms
in, for example prefilling the user's address based on earlier user
input.</p>
<p>The <dfn
title="attr-input-autocomplete"><code>autocomplete</code></dfn>
attribute is an <span>enumerated attribute</span>. The attribute has
three states. The <code title="attr-input-autocomplete-on">on</code>
keyword maps to the <dfn
title="attr-input-autocomplete-on-state">on</dfn> state, and the
<code title="attr-input-autocomplete-off">off</code> keyword maps to
the <dfn title="attr-input-autocomplete-off-state">off</dfn>
state. The attribute may also be omitted. The <i>missing value
default</i> is the <dfn
title="attr-input-autocomplete-default-state">default</dfn>
state.</p>
<p>The <span title="attr-input-autocomplete-off-state">off</span>
state indicates either that the control's input data is particularly
sensitive (for example the activation code for a nuclear weapon); or
that it is a value that will never be reused (for example a
one-time-key for a bank login) and the user will therefore have to
explicitly enter the data each time, instead of being able to rely
on the UA to prefill the value for him; or that the document
provides its own autocomplete mechanism and does not want the user
agent to provide autocompletion values.</p>
<p>Conversely, the <span
title="attr-input-autocomplete-on-state">on</span> state indicates
that the value is not particularly sensitive and the user can expect
to be able to rely on his user agent to remember values he has
entered for that control.</p>
<p>The <span
title="attr-input-autocomplete-default-state">default</span> state
indicates that the user agent is to use the <code
title="attr-form-autocomplete">autocomplete</code> attribute on the
element's <span>form owner</span> instead. (By default, the <code
title="attr-form-autocomplete">autocomplete</code> attribute of
<code>form</code> elements is in the <span
title="attr-form-autocomplete-on-state">on</span> state.)</p>
<div class="impl">
<p>Each <code>input</code> element has a <dfn>resulting
autocompletion state</dfn>, which is either <i title="">on</i> or <i
title="">off</i>.</p>
<p>When an <code>input</code> element is in one of the following
conditions, the <code>input</code> element's <span>resulting
autocompletion state</span> is <i title="">on</i>; otherwise, the
<code>input</code> element's <span>resulting autocompletion
state</span> is <i title="">off</i>:</p>
<ul class="brief">
<li>Its <code title="attr-input-autocomplete">autocomplete</code>
attribute is in the <span
title="attr-input-autocomplete-on-state">on</span> state.</li>
<li>Its <code title="attr-input-autocomplete">autocomplete</code>
attribute is in the <span
title="attr-input-autocomplete-default-state">default</span> state,
and the element has no <span>form owner</span>.</li>
<li>Its <code title="attr-input-autocomplete">autocomplete</code>
attribute is in the <span
title="attr-input-autocomplete-default-state">default</span> state,
and the element's <span>form owner</span>'s <code
title="attr-form-autocomplete">autocomplete</code> attribute is in
the <span title="attr-form-autocomplete-on-state">on</span>
state.</li>
</ul>
<p>When an <code>input</code> element's <span>resulting
autocompletion state</span> is <i title="">on</i>, the user agent
may store the value entered by the user so that if the user returns
to the page, the UA can prefill the form. Otherwise, the user agent
should not remember the control's <span
title="concept-fe-value">value</span>, and should not offer past
values to the user.</p>
<p>In addition, if the <span>resulting autocompletion state</span>
is <i title="">off</i>, <a href="#history-autocomplete">values are
reset</a> when <span title="traverse the history">traversing the
history</span>.</p>
<p>The autocompletion mechanism must be implemented by the user
agent acting as if the user had modified the element's <span
title="concept-fe-value">value</span>, and must be done at a time
where the element is <i title="concept-input-mutable">mutable</i>
(e.g. just after the element has been inserted into the document, or
when the user agent <span title="stop parsing">stops
parsing</span>).</p>
</div>
<div class="example">
<p>Banks frequently do not want UAs to prefill login
information:</p>
<pre><p><label>Account: <input type="text" name="ac" autocomplete="off"></label></p>
<p><label>PIN: <input type="password" name="pin" autocomplete="off"></label></p></pre>
</div>
<div class="impl">
<p>A user agent may allow the user to override the <span>resulting
autocompletion state</span> and set it to always <i title="">on</i>,
always allowing values to be remembered and prefilled), or always <i
title="">off</i>, never remembering values. However, the ability to
override the <span>resulting autocompletion state</span> to <i
title="">on</i> should not be trivially accessible, as there are
significant security implications for the user if all values are
always remembered, regardless of the site's preferences.</p>
</div>
<h6>The <code title="attr-input-list">list</code> attribute</h6>
<p>The <dfn title="attr-input-list"><code>list</code></dfn>
attribute is used to identify an element that lists predefined
options suggested to the user.</p>
<p>If present, its value must be the ID of a <code>datalist</code>
element in the same document.</p>
<div class="impl">
<p>The <dfn title="concept-input-list">suggestions source
element</dfn> is the first element in the document in <span>tree
order</span> to have an ID equal to the value of the <code
title="attr-input-list">list</code> attribute, if that element is a
<code>datalist</code> element. If there is no <code
title="attr-input-list">list</code> attribute, or if there is no
element with that ID, or if the first element with that ID is not a
<code>datalist</code> element, then there is no <span
title="concept-input-list">suggestions source element</span>.</p>
<p>If there is a <span title="concept-input-list">suggestions source
element</span>, then, when the user agent is allowing the user to
edit the <code>input</code> element's <span
title="concept-fe-value">value</span>, the user agent should offer
the suggestions represented by the <span
title="concept-input-list">suggestions source element</span> to the
user in a manner suitable for the type of control used. The user
agent may use the suggestion's <span
title="concept-option-label">label</span> to identify the suggestion
if appropriate. If the user selects a suggestion, then the
<code>input</code> element's <span
title="concept-fe-value">value</span> must be set to the selected
suggestion's <span title="concept-option-value">value</span>, as if
the user had written that value himself.</p>
<p>User agents must filter the suggestions to hide suggestions that
the user would not be allowed to enter as the <code>input</code>
element's <span title="concept-fe-value">value</span>, and should
filter the suggestions to hide suggestions that would cause the
element to not <span title="concept-fv-valid">satisfy its
constraints</span>.</p>
<hr>
<p>If the <code title="attr-input-list">list</code> attribute does
not apply, there is no <span title="concept-input-list">suggestions
source element</span>.</p>
</div>
<div class="example">
<p>This URL field offers some suggestions.</p>
<pre><label>Homepage: <input name=hp type=url list=hpurls></label>
<datalist id=hpurls>
<option value="http://www.google.com/" label="Google">
<option value="http://www.reddit.com/" label="Reddit">
</datalist></pre>
<p>Other URLs from the user's history might show also; this is up
to the user agent.</p>
</div>
<h6>The <code title="attr-input-readonly">readonly</code> attribute</h6>
<p>The <dfn title="attr-input-readonly"><code>readonly</code></dfn>
attribute is a <span>boolean attribute</span> that controls whether
or not the use can edit the form control. <span class="impl">When
specified, the element is <i
title="concept-input-immutable">immutable</i>.</span></p>
<div class="impl">
<p><strong>Constraint validation</strong>: If the <code
title="attr-input-readonly">readonly</code> attribute is specified
on an <code>input</code> element, the element is <span>barred from
constraint validation</span>.</p>
</div>
<div class="example">
<p>In the following example, the existing product identifiers
cannot be modified, but they are still displayed as part of the
form, for consistency with the row representing a new product
(where the identifier is not yet filled in).</p>
<pre><form action="products.cgi" method=post enctype="multipart/formdata">
<table>
<tr> <th> Product ID <th> Product name <th> Price <th> Action
<tr>
<td> <input readonly name="1.pid" value="H412">
<td> <input required name="1.pname" value="Floor lamp Ulke">
<td> $<input required type=number min=0 step=0.01 name="1.pprice" value="49.99">
<td> <button formnovalidate name="action" value="delete:1">Delete</button>
<tr>
<td> <input readonly name="2.pid" value="FG28">
<td> <input required name="2.pname" value="Table lamp Ulke">
<td> $<input required type=number min=0 step=0.01 name="2.pprice" value="24.99">
<td> <button formnovalidate name="action" value="delete:2">Delete</button>
<tr>
<td> <input required name="3.pid" value="" pattern="[A-Z0-9]+">
<td> <input required name="3.pname" value="">
<td> $<input required type=number min=0 step=0.01 name="3.pprice" value="">
<td> <button formnovalidate name="action" value="delete:3">Delete</button>
</table>
<p> <button formnovalidate name="action" value="add">Add</button> </p>
<p> <button name="action" value="update">Save</button> </p>
</form></pre>
</div>
<h6>The <code title="attr-input-size">size</code> attribute</h6>
<p>The <dfn title="attr-input-size"><code>size</code></dfn>
attribute gives the number of characters that, in a visual
rendering, the user agent is to allow the user to see while editing
the element's <span title="concept-fe-value">value</span>.</p>
<p>The <code title="attr-input-size">size</code> attribute, if
specified, must have a value that is a <span>valid non-negative
integer</span> greater than zero.</p>
<div class="impl">
<p>If the attribute is present, then its value must be parsed using
the <span>rules for parsing non-negative integers</span>, and if the
result is a number greater than zero, then the user agent should
ensure that at least that many characters are visible.</p>
<p>The <code title="dom-input-size">size</code> IDL attribute is
<span>limited to only non-negative numbers greater than
zero</span>.</p>
</div>
<h6>The <code title="attr-input-required">required</code> attribute</h6>
<p>The <dfn title="attr-input-required"><code>required</code></dfn>
attribute is a <span>boolean attribute</span>. When specified, the
element is <dfn
title="concept-input-required"><i>required</i></dfn>.</p>
<div class="impl">
<p><strong>Constraint validation</strong>: If the element is <i
title="concept-input-required">required</i>, and its <code
title="dom-input-value">value</code> IDL attribute applies and is in
the mode <span title="dom-input-value-value">value</span>, and the
element is <i title="concept-input-mutable">mutable</i>, and the
element's <span title="concept-fe-value">value</span> is the empty
string, then the element is <span>suffering from being
missing</span>.</p>
</div>
<div class="example">
<p>The following form has two required fields, one for an e-mail
address and one for a password. It also has a third field that is
only considerd valid if the user types the same password in the
password field and this third field.</p>
<pre><h1>Create new account</h1>
<form action="/newaccount" method=post>
<p>
<label for="username">E-mail address:</label>
<input id="username" type=email required name=un>
<p>
<label for="password1">Password:</label>
<input id="password1" type=password required name=up>
<p>
<label for="password2">Confirm password:</label>
<input id="password2" type=password onforminput="setCustomValidity(value != password1.value ? 'Passwords do not match.' : '')">
<p>
<input type=submit value="Create account">
</form></pre>
</div>
<h6>The <code title="attr-input-multiple">multiple</code> attribute</h6>
<p>The <dfn title="attr-input-multiple"><code>multiple</code></dfn>
attribute is a <span>boolean attribute</span> that indicates whether
the user is to be allowed to specify more than one value.</p>
<div class="example">
<p>The following extract shows how an e-mail client's "Cc" field
could accept multiple e-mail addresses.</p>
<pre><label>Cc: <input type=email multiple name=cc></label></pre>
</div>
<div class="example">
<p>The following extract shows how an e-mail client's "Attachments"
field could accept multiple files for upload.</p>
<pre><label>Attachments: <input type=file multiple name=att></label></pre>
</div>
<h6>The <code title="attr-input-maxlength">maxlength</code> attribute</h6>
<p>The <dfn
title="attr-input-maxlength"><code>maxlength</code></dfn>
attribute<span class="impl">, when it applies,</span> is a <span
title="attr-fe-maxlength">form control <code
title="">maxlength</code> attribute</span><span class="impl">
controlled by the <code>input</code> element's <span
title="concept-input-value-dirty-flag">dirty value
flag</span></span>.</p>
<p>If the <code>input</code> element has a <span>maximum allowed
value length</span>, then the <span>code-point length</span> of the
value of the element's <code title="attr-input-value">value</code>
attribute must be equal to or less than the element's <span>maximum
allowed value length</span>.</p>
<div class="example">
<p>The following extract shows how a messaging client's text entry
could be arbitrarily restricted to a fixed number of characters,
thus forcing any conversion through this medium to be terse and
discouraging intelligent discourse.</p>
<pre>What are you doing? <input name=status maxlength=140></pre>
</div>
<h6>The <code title="attr-input-pattern">pattern</code> attribute</h6>
<p>The <dfn title="attr-input-pattern"><code>pattern</code></dfn>
attribute specifies a regular expression against which the control's
<span title="concept-fe-value">value</span> is to be checked.</p>
<p>If specified, the attribute's value must match the JavaScript <i
title="">Pattern</i> production. <a
href="#refsECMA262">[ECMA262]</a></p>
<div class="impl">
<p><strong>Constraint validation</strong>: If the element's <span
title="concept-fe-value">value</span> is not the empty string, and
the element's <code title="attr-input-pattern">pattern</code>
attribute is specified and the attribute's value, when compiled as a
JavaScript regular expression with the <code title="">global</code>,
<code title="">ignoreCase</code>, and <code
title="">multiline</code> flags <em>disabled</em> (see ECMA262
Edition 3, sections 15.10.7.2 through 15.10.7.4), compiles
successfully but the resulting regular expression does not match the
entirety of the element's <span
title="concept-fe-value">value</span>, then the element is
<span>suffering from a pattern mismatch</span>. <a
href="#refsECMA262">[ECMA262]</a></p>
<p class="note">This implies that the regular expression language
used for this attribute is the same as that used in JavaScript,
except that the <code title="attr-input-pattern">pattern</code>
attribute must match the entire value, not just any subset (somewhat
as if it implied a <code title="">^(?:</code> at the start of the
pattern and a <code title="">)$</code> at the end).</p>
</div>
<p>When an <code>input</code> element has a <code
title="attr-input-pattern">pattern</code> attribute specified,
authors should include a <code title="attr-title">title</code>
attribute to give a description of the pattern. User agents may use
the contents of this attribute, if it is present, when informing the
user that the pattern is not matched, or at any other suitable time,
such as in a tooltip or read out by assistive technology when the
control gains focus.</p>
<div class="example">
<p>For example, the following snippet:</p>
<pre><label> Part number:
<input pattern="[0-9][A-Z]{3}" name="part"
title="A part number is a digit followed by three uppercase letters."/>
</label></pre>
<p>...could cause the UA to display an alert such as:</p>
<pre><samp>A part number is a digit followed by three uppercase letters.
You cannot complete this form until the field is correct.</samp></pre>
</div>
<p>When a control has a <code>pattern</code> attribute, the
<code>title</code> attribute, if used, must describe the pattern.
Additional information could also be included, so long as it assists
the user in filling in the control. Otherwise, assistive technology
would be impaired.</p>
<p class="example">For instance, if the title attribute contained
the caption of the control, assistive technology could end up saying
something like <samp>The text you have entered does not match the
required pattern. Birthday</samp>, which is not useful.</p>
<p>UAs may still show the <code>title</code> in non-error situations
(for example, as a tooltip when hovering over the control), so
authors should be careful not to word <code>title</code>s as if an
error has necessarily occurred.</p>
<h6>The <code title="attr-input-min">min</code> and <code
title="attr-input-max">max</code> attributes</h6>
<p>The <dfn title="attr-input-min"><code>min</code></dfn> and <dfn
title="attr-input-max"><code>max</code></dfn> attributes indicate
the allowed range of values for the element.</p>
<div class="impl">
<p>Their syntax is defined by the section that defines the <code
title="attr-input-type">type</code> attribute's current state.</p>
<p>If the element has a <code title="attr-input-min">min</code>
attribute, and the result of applying the <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span> to the value of the <code
title="attr-input-min">min</code> attribute is a number, then that
number is the element's <dfn
title="concept-input-min">minimum</dfn>; otherwise, if the <code
title="attr-input-type">type</code> attribute's current state
defines a <dfn title="concept-input-min-default">default
minimum</dfn>, then that is the <span
title="concept-input-min">minimum</span>; otherwise, the element has
no <span title="concept-input-min">minimum</span>.</p>
<p><strong>Constraint validation</strong>: When the element has a
<span title="attr-input-min">minimum</span>, and the result of
applying the <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span> to the string given by the element's <span
title="concept-fe-value">value</span> is a number, and the number
obtained from that algorithm is less than the <span
title="attr-input-min">minimum</span>, the element is
<span>suffering from an underflow</span>.</p>
<p>The <code title="attr-input-min">min</code> attribute also
defines the <span title="concept-input-min-zero">step
base</span>.</p>
<p>If the element has a <code title="attr-input-max">max</code>
attribute, and the result of applying the <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span> to the value of the <code
title="attr-input-max">max</code> attribute is a number, then that
number is the element's <dfn
title="concept-input-max">maximum</dfn>; otherwise, if the <code
title="attr-input-type">type</code> attribute's current state
defines a <dfn title="concept-input-max-default">default
maximum</dfn>, then that is the <span
title="concept-input-max">maximum</span>; otherwise, the element has
no <span title="concept-input-max">maximum</span>.</p>
<p><strong>Constraint validation</strong>: When the element has a
<span title="attr-input-max">maximum</span>, and the result of
applying the <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span> to the string given by the element's <span
title="concept-fe-value">value</span> is a number, and the number
obtained from that algorithm is more than the <span
title="attr-input-max">maximum</span>, the element is
<span>suffering from an overflow</span>.</p>
</div>
<p>The <code title="attr-input-max">max</code> attribute's value
(the <span title="concept-input-max">maximum</span>) must not be
less than the <code title="attr-input-min">min</code> attribute's
value (its <span title="concept-input-min">minimum</span>).</p>
<div class="impl">
<p class="note">If an element has a <span
title="attr-input-max">maximum</span> that is less than its <span
title="attr-input-min">minimum</span>, then so long as the element
has a <span title="concept-fe-value">value</span>, it will either be
<span>suffering from an underflow</span> or <span>suffering from an
overflow</span>.</p>
</div>
<div class="example">
<p>The following date control limits input to dates that are before
the 1980s:</p>
<pre><input name=bday type=date max="1979-12-31"></pre>
</div>
<div class="example">
<p>The following number control limits input to whole numbers
greater than zero:</p>
<pre><input name=quantity required type=number min=1 value=1></pre>
</div>
<h6>The <code title="attr-input-step">step</code> attribute</h6>
<p>The <dfn title="attr-input-step"><code>step</code></dfn>
attribute indicates the granularity that is expected (and required)
of the <span title="concept-fe-value">value</span>, by limiting the
allowed values. <span class="impl">The section that defines the
<code title="attr-input-type">type</code> attribute's current state
also defines the <dfn title="concept-input-step-default">default
step</dfn> and the <dfn title="concept-input-step-scale">step scale
factor</dfn>, which are used in processing the attribute as
described below.</span></p>
<p>The <code title="attr-input-step">step</code> attribute, if
specified, must either have a value that is a <span>valid floating
point number</span> that <span title="rules for parsing floating
point number values">parses</span> to a number that is greater than
zero, or must have a value that is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">any</code>".</p>
<div class="impl">
<p>The attribute provides the <dfn
title="concept-input-step">allowed value step</dfn> for the element,
as follows:</p>
<ol>
<li>If the attribute is absent, then the <span
title="concept-input-step">allowed value step</span> is the <span
title="concept-input-step-default">default step</span> multiplied
by the <span title="concept-input-step-scale">step scale
factor</span>.</li>
<li>Otherwise, if the attribute's value is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">any</code>", then there is no <span
title="concept-input-step">allowed value step</span>.</li>
<li>Otherwise, if the <span>rules for parsing floating point number
values</span>, when they are applied to the attribute's value,
return an error, zero, or a number less than zero, then the <span
title="concept-input-step">allowed value step</span> is the <span
title="concept-input-step-default">default step</span> multiplied
by the <span title="concept-input-step-scale">step scale
factor</span>.</li>
<li>Otherwise, the <span title="concept-input-step">allowed value
step</span> is the number returned by the <span>rules for parsing
floating point number values</span> when they are applied to the
attribute's value, multiplied by the <span
title="concept-input-step-scale">step scale factor</span>.</li>
</ol>
<p>The <dfn title="concept-input-min-zero">step base</dfn> is the
result of applying the <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span> to the value of the <code
title="attr-input-min">min</code> attribute, unless the element does
not have a <code title="attr-input-min">min</code> attribute
specified or the result of applying that algorithm is an error, in
which case the <span title="concept-input-min-zero">step base</span>
is zero.</p>
<p><strong>Constraint validation</strong>: When the element has an
<span title="concept-input-step">allowed value step</span>, and the
result of applying the <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span> to the string given by the element's <span
title="concept-fe-value">value</span> is a number, and that
number subtracted from the <span title="concept-input-min-zero">step
base</span> is not an integral multiple of the <span
title="concept-input-step">allowed value step</span>, the element is
<span>suffering from a step mismatch</span>.</p>
</div>
<div class="example">
<p>The following range control only accepts values in the range
0..1, and allows 256 steps in that range:</p>
<pre><input name=opacity type=range min=0 max=1 step=0.00392156863></pre>
</div>
<div class="example">
<p>The following control allows any time in the day to be selected,
with any accuracy (e.g. thousandth-of-a-second accuracy or
more):</p>
<pre><input name=favtime type=time step=any></pre>
<p>Normally, time controls are limited to an accuracy of one
minute.</p>
</div>
<h6>The <code title="attr-input-placeholder">placeholder</code> attribute</h6>
<!-- similar text in the <textarea> section -->
<p>The <dfn
title="attr-input-placeholder"><code>placeholder</code></dfn>
attribute represents a <em>short</em> hint (a word or short phrase)
intended to aid the user with data entry. A hint could be a sample
value or a brief description of the expected format. The attribute,
if specified, must have a value that contains no U+000A LINE FEED
(LF) or U+000D CARRIAGE RETURN (CR) characters.</p>
<p class="note">For a longer hint or other advisory text, the <code
title="attr-title">title</code> attribute is more appropriate.</p>
<p>The <code title="attr-input-placeholder">placeholder</code>
attribute should not be used as an alternative to a
<code>label</code>.</p>
<div class="impl">
<p>User agents should present this hint to the user, after having
<span title="strip line breaks">stripped line breaks</span> from it,
when the element's <span title="concept-fe-value">value</span> is
the empty string and the control is not focused (e.g. by displaying
it inside a blank unfocused control).</p>
</div>
<div class="example">
<p>Here is an example of a mail configuration user interface that
uses the <code title="attr-input-placeholder">placeholder</code>
attribute:</p>
<pre><fieldset>
<legend>Mail Account</legend>
<p><label>Name: <input type="text" name="fullname" placeholder="John Ratzenberger"></label></p>
<p><label>Address: <input type="email" name="address" placeholder="john@example.net"></label></p>
<p><label>Password: <input type="password" name="password"></label></p>
<p><label>Description: <input type="text" name="desc" placeholder="My Email Account"></label></p>
</fieldset></pre>
</div>
<h5>Common <code>input</code> element APIs</h5>
<dl class="domintro">
<dt><var title="">input</var> . <code title="dom-input-value">value</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current <span title="concept-fe-value">value</span>
of the form control.</p>
<p>Can be set, to change the value.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if it is
set to any value other than the empty string when the control is a
file upload control.</p>
</dd>
<dt><var title="">input</var> . <code title="dom-input-checked">checked</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current <span
title="concept-fe-checked">checkedness</span> of the form
control.</p>
<p>Can be set, to change the <span
title="concept-fe-checked">checkedness</span>.</p>
</dd>
<dt><var title="">input</var> . <code title="dom-input-files">files</code></dt>
<dd>
<p>Returns a <code>FileList</code> object listing the <span
title="concept-input-type-file-selected">selected files</span> of
the form control.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if the
control isn't a file control.</p>
</dd>
<dt><var title="">input</var> . <code title="dom-input-valueAsDate">valueAsDate</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns a <code>Date</code> object representing the form
control's <span title="concept-fe-value">value</span>, if
applicable; otherwise, returns null.</p>
<p>Can be set, to change the value.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if the
control isn't date- or time-based.</p>
</dd>
<dt><var title="">input</var> . <code title="dom-input-valueAsNumber">valueAsNumber</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns a number representing the form control's <span
title="concept-fe-value">value</span>, if applicable; otherwise,
returns null.</p>
<p>Can be set, to change the value.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if the
control is neither date- or time-based nor numeric.</p>
</dd>
<dt><var title="">input</var> . <code title="dom-input-stepUp">stepUp</code>( [ <var title="">n</var> ] )</dt>
<dt><var title="">input</var> . <code title="dom-input-stepDown">stepDown</code>( [ <var title="">n</var> ] )</dt>
<dd>
<p>Changes the form control's <span
title="concept-fe-value">value</span> by the value given in the
<code title="attr-input-step">step</code> attribute, multiplied by
<var title="">n</var>. The default is 1.</p>
<p>Throws <code>INVALID_STATE_ERR</code> exception if the control
is neither date- or time-based nor numeric, if the <code
title="attr-input-step">step</code> attribute's value is "<code
title="">any</code>", if the current <span
title="concept-fe-value">value</span> could not be parsed, or if
stepping in the given direction by the given amount would take the
value out of range.</p>
</dd>
<dt><var title="">input</var> . <code title="dom-input-list">list</code></dt>
<dd>
<p>Returns the <code>datalist</code> element indicated by the
<code title="attr-input-list">list</code> attribute.</p>
</dd>
<dt><var title="">input</var> . <code title="dom-input-selectedOption">selectedOption</code></dt>
<dd>
<p>Returns the <code>option</code> element from the
<code>datalist</code> element indicated by the <code
title="attr-input-list">list</code> attribute that matches the
form control's <span title="concept-fe-value">value</span>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-input-value"><code>value</code></dfn> IDL
attribute allows scripts to manipulate the <span
title="concept-fe-value">value</span> of an <code>input</code>
element. The attribute is in one of the following modes, which
define its behavior:</p>
<dl>
<dt><dfn title="dom-input-value-value">value</dfn>
<dd>On getting, it must return the current <span
title="concept-fe-value">value</span> of the element. On setting,
it must set the element's <span
title="concept-fe-value">value</span> to the new value, set the
element's <span title="concept-input-value-dirty-flag">dirty value
flag</span> to true, and then invoke the <span>value sanitization
algorithm</span>, if the element's <code
title="attr-input-type">type</code> attribute's current state
defines one.</dd>
<dt><dfn title="dom-input-value-default">default</dfn>
<dd>On getting, if the element has a <code
title="attr-input-value">value</code> attribute, it must return
that attribute's value; otherwise, it must return the empty
string. On setting, it must set the element's <code
title="attr-input-value">value</code> attribute to the new
value.</dd>
<dt><dfn title="dom-input-value-default-on">default/on</dfn>
<dd>On getting, if the element has a <code
title="attr-input-value">value</code> attribute, it must return
that attribute's value; otherwise, it must return the string "<code
title="">on</code>". On setting, it must set the element's <code
title="attr-input-value">value</code> attribute to the new
value.</dd>
<dt><dfn title="dom-input-value-filename">filename</dfn>
<dd>On getting, it must return the string "<code
title="">C:\fakepath\</code>" followed by the filename of the first
file in the list of <span
title="concept-input-type-file-selected">selected files</span>, if
any, or the empty string if the list is empty. On setting, if the
new value is the empty string, it must empty the list of <span
title="concept-input-type-file-selected">selected files</span>;
otherwise, it must throw an <code>INVALID_STATE_ERR</code>
exception.</dd>
</dl>
<hr>
<p>The <dfn title="dom-input-checked"><code>checked</code></dfn> IDL
attribute allows scripts to manipulate the <span
title="concept-fe-checked">checkedness</span> of an
<code>input</code> element. On getting, it must return the current
<span title="concept-fe-checked">checkedness</span> of the element;
and on setting, it must set the element's <span
title="concept-fe-checked">checkedness</span> to the new value and
set the element's <span
title="concept-input-checked-dirty-flag">dirty checkedness
flag</span> to true.</p>
<hr>
<p>The <dfn title="dom-input-files"><code>files</code></dfn> IDL
attribute allows scripts to access the element's <span
title="concept-input-type-file-selected">selected files</span>. On
getting, if the IDL attribute applies, it must return a
<code>FileList</code> object that represents the current <span
title="concept-input-type-file-selected">selected files</span>. The
same object must be returned until the list of <span
title="concept-input-type-file-selected">selected files</span>
changes. If the IDL attribute does not apply, then it must instead
throw an <code>INVALID_STATE_ERR</code> exception. <a
href="#refsFILEAPI">[FILEAPI]</a></p>
<hr>
<p>The <dfn
title="dom-input-valueAsDate"><code>valueAsDate</code></dfn> IDL
attribute represents the <span
title="concept-fe-value">value</span> of the element, interpreted
as a date.</p>
<p>On getting, if the <code
title="dom-input-valueAsDate">valueAsDate</code> attribute does not
apply, as defined for the <code>input</code> element's <code
title="attr-input-type">type</code> attribute's current state, then
return null. Otherwise, run the <span
title="concept-input-value-string-date">algorithm to convert a
string to a <code>Date</code> object</span> defined for that state;
if the algorithm returned a <code>Date</code> object, then return
it, otherwise, return null.</p>
<p>On setting, if the <code
title="dom-input-valueAsDate">valueAsDate</code> attribute does not
apply, as defined for the <code>input</code> element's <code
title="attr-input-type">type</code> attribute's current state, then
throw an <code>INVALID_STATE_ERR</code> exception; otherwise, if
the new value is null, then set the <span
title="concept-fe-value">value</span> of the element to the empty
string; otherwise, run the <span
title="concept-input-value-date-string">algorithm to convert a
<code>Date</code> object to a string</span>, as defined for that
state, on the new value, and set the <span
title="concept-fe-value">value</span> of the element to resulting
string.</p>
<hr>
<p>The <dfn
title="dom-input-valueAsNumber"><code>valueAsNumber</code></dfn> IDL
attribute represents the <span title="concept-fe-value">value</span>
of the element, interpreted as a number.</p>
<p>On getting, if the <code
title="dom-input-valueAsNumber">valueAsNumber</code> attribute does
not apply, as defined for the <code>input</code> element's <code
title="attr-input-type">type</code> attribute's current state, then
return a Not-a-Number (NaN) value. Otherwise, if the <code
title="dom-input-valueAsDate">valueAs<em>Date</em></code>
attribute applies, run the <span
title="concept-input-value-string-date">algorithm to convert a
string to a <code>Date</code> object</span> defined for that state;
if the algorithm returned a <code>Date</code> object, then return
the <i>time value</i> of the object (the number of milliseconds from
midnight UTC the morning of 1970-01-01 to the time represented by
the <code>Date</code> object), otherwise, return a Not-a-Number
(NaN) value. Otherwise, run the <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span> defined for that state; if the algorithm
returned a number, then return it, otherwise, return a Not-a-Number
(NaN) value.</p>
<p>On setting, if the <code
title="dom-input-valueAsNumber">valueAsNumber</code> attribute does
not apply, as defined for the <code>input</code> element's <code
title="attr-input-type">type</code> attribute's current state, then
throw an <code>INVALID_STATE_ERR</code> exception. Otherwise, if
the <code
title="dom-input-valueAsDate">valueAs<em>Date</em></code>
attribute applies, run the <span
title="concept-input-value-date-string">algorithm to convert a
<code>Date</code> object to a string</span> defined for that state,
passing it a <code>Date</code> object whose <i>time value</i> is the
new value, and set the <span title="concept-fe-value">value</span>
of the element to resulting string. Otherwise, run the <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, as defined for that state, on the new
value, and set the <span title="concept-fe-value">value</span> of
the element to resulting string.</p>
<hr>
<p>The <dfn title="dom-input-stepDown"><code>stepDown(<var
title="">n</var>)</code></dfn> and <dfn
title="dom-input-stepUp"><code>stepUp(<var
title="">n</var>)</code></dfn> methods, when invoked, must run the
following algorithm:</p>
<ol>
<li><p>If the <code title="dom-input-stepDown">stepDown()</code> and
<code title="dom-input-stepUp">stepUp()</code> methods do not
apply, as defined for the <code>input</code> element's <code
title="attr-input-type">type</code> attribute's current state, then
throw an <code>INVALID_STATE_ERR</code> exception, and abort these
steps.</p></li>
<li><p>If the element has no <span
title="concept-input-step">allowed value step</span>, then throw an
<code>INVALID_STATE_ERR</code> exception, and abort these
steps.</p></li>
<li><p>If applying the <span
title="concept-input-value-string-number">algorithm to convert a
string to a number</span> to the string given by the element's
<span title="concept-fe-value">value</span> results in an error,
then throw an <code>INVALID_STATE_ERR</code> exception, and abort
these steps; otherwise, let <var title="">value</var> be the result
of that algorithm.</p></li>
<li><p>Let <var title="">n</var> be the argument, or 1 if the
argument was omitted.</p></li>
<li><p>Let <var title="">delta</var> be the <span
title="concept-input-step">allowed value step</span> multiplied by
<var title="">n</var>.</p></li>
<li><p>If the method invoked was the <code
title="dom-input-stepDown">stepDown()</code> method, negate <var
title="">delta</var>.</p></li>
<li><p>Let <var title="">value</var> be the result of adding <var
title="">delta</var> to <var title="">value</var>.</p></li>
<li><p>If the element has a <span
title="concept-input-min">minimum</span>, and the <var
title="">value</var> is less than that <span
title="concept-input-min">minimum</span>, then throw a
<code>INVALID_STATE_ERR</code> exception.</p></li>
<li><p>If the element has a <span
title="concept-input-max">maximum</span>, and the <var
title="">value</var> is greater than that <span
title="concept-input-max">maximum</span>, then throw a
<code>INVALID_STATE_ERR</code> exception.</p></li>
<li><p>Let <var title="">value as string</var> be the result of
running the <span
title="concept-input-value-number-string">algorithm to convert a
number to a string</span>, as defined for the <code>input</code>
element's <code title="attr-input-type">type</code> attribute's
current state, on <var title="">value</var>.</p></li>
<li><p>Set the <span title="concept-fe-value">value</span> of the
element to <var title="">value as string</var>.</p></li>
</ol>
<hr>
<p>The <dfn title="dom-input-list"><code>list</code></dfn> IDL
attribute must return the current <span
title="concept-input-list">suggestions source element</span>, if
any, or null otherwise.</p>
<p>The <dfn
title="dom-input-selectedOption"><code>selectedOption</code></dfn>
IDL attribute must return the first <code>option</code> element, in
<span>tree order</span>, to be a child of the <span
title="concept-input-list">suggestions source element</span> and
whose <span title="concept-option-value">value</span> matches the
<code>input</code> element's <span
title="concept-fe-value">value</span>, if any. If there is no <span
title="concept-input-list">suggestions source element</span>, or if
it contains no matching <code>option</code> element, then the <code
title="dom-input-selectedOption">selectedOption</code> attribute
must return null.</p>
</div>
<div class="impl">
<h5>Common event behaviors</h5>
<p>When the <dfn title="event-input-input"><code>input</code></dfn>
event applies, any time the user causes the element's <span
title="concept-fe-value">value</span> to change, the user agent must
<span>queue a task</span> to <span>fire a simple event</span> that
bubbles named <code title="event-input">input</code> at the
<code>input</code> element, then <span>broadcast <code
title="event-forminput">forminput</code> events</span> at the
<code>input</code> element's <span>form owner</span>. User agents
may wait for a suitable break in the user's interaction before
queuing the task; for example, a user agent could wait for the user
to have not hit a key for 100ms, so as to only fire the event when
the user pauses, instead of continuously for each keystroke.</p>
<!-- same text is present in the <textarea> section -->
<p class="example">Examples of a user changing the element's <span
title="concept-fe-value">value</span> would include the user typing
into a text field, pasting a new value into the field, or undoing an
edit in that field. Some user interactions do not cause changes to
the value, e.g. hitting the "delete" key in an empty text field, or
replacing some text in the field with text from the clipboard that
happens to be exactly the same text.</p>
<p>When the <dfn
title="event-input-change"><code>change</code></dfn> event applies,
if the element does not have an <span>activation behavior</span>
defined but uses a user interface that involves an explicit commit
action, then any time the user commits a change to the element's
<span title="concept-fe-value">value</span> or list of <span
title="concept-input-type-file-selected">selected files</span>, the
user agent must <span>queue a task</span> to <span>fire a simple
event</span> that bubbles named <code
title="event-change">change</code> at the <code>input</code>
element, then <span>broadcast <code
title="event-formchange">formchange</code> events</span> at the
<code>input</code> element's <span>form owner</span>.</p>
<p class="example">An example of a user interface with a commit
action would be a <span title="attr-input-type-file">File
Upload</span> control that consists of a single button that brings
up a file selection dialog: when the dialog is closed, if that the
<span title="concept-input-type-file-selected">file selection</span>
changed as a result, then the user has committed a new <span
title="concept-input-type-file-selected">file selection</span>.</p>
<p class="example">Another example of a user interface with a commit
action would be a <span title="attr-input-type-date">Date</span>
control that allows both text-based user input and user selection
from a drop-down calendar: while text input might not have an
explicit commit step, selecting a date from the drop down calendar
and then dismissing the drop down would be a commit action.</p>
<p>When the user agent changes the element's <span
title="concept-fe-value">value</span> on behalf of the user (e.g. as
part of a form prefilling feature), the user agent must follow these
steps:</p>
<ol>
<li>If the <code title="event-input-input">input</code> event
applies, <span>queue a task</span> to <span>fire a simple
event</span> that bubbles named <code
title="event-input">input</code> at the <code>input</code>
element.</li>
<li>If the <code title="event-input-input">input</code> event
applies, <span>broadcast <code
title="event-forminput">forminput</code> events</span> at the
<code>input</code> element's <span>form owner</span>.</li>
<li>If the <code title="event-input-change">change</code> event
applies, <span>queue a task</span> to <span>fire a simple
event</span> that bubbles named <code
title="event-change">change</code> at the <code>input</code>
element.</li>
<li>If the <code title="event-input-change">change</code> event
applies, <span>broadcast <code
title="event-formchange">formchange</code> events</span> at the
<code>input</code> element's <span>form owner</span>.</li>
</ol>
<p class="note">In addition, when the <code
title="event-input-change">change</code> event applies, <code
title="event-change">change</code> events can also be fired as part
of the element's <span>activation behavior</span> and as part of the
<span>unfocusing steps</span>.</p>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <span>user interaction task
source</span>.</p>
</div>
<h4>The <dfn><code>button</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dd><span title="category-listed">Listed</span>, <span title="category-label">labelable</span>, and <span title="category-submit">submittable</span> <span>form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>, but there must be no <span>interactive content</span> descendant.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-fe-autofocus">autofocus</code></dd>
<dd><code title="attr-fe-disabled">disabled</code></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-fs-formaction">formaction</code></dd>
<dd><code title="attr-fs-formenctype">formenctype</code></dd>
<dd><code title="attr-fs-formmethod">formmethod</code></dd>
<dd><code title="attr-fs-formnovalidate">formnovalidate</code></dd>
<dd><code title="attr-fs-formtarget">formtarget</code></dd>
<dd><code title="attr-fe-name">name</code></dd>
<dd><code title="attr-button-type">type</code></dd>
<dd><code title="attr-button-value">value</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLButtonElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-fe-autofocus">autofocus</span>;
attribute boolean <span title="dom-fe-disabled">disabled</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
attribute DOMString <span title="dom-fs-formAction">formAction</span>;
attribute DOMString <span title="dom-fs-formEnctype">formEnctype</span>;
attribute DOMString <span title="dom-fs-formMethod">formMethod</span>;
attribute DOMString <span title="dom-fs-formNoValidate">formNoValidate</span>;
attribute DOMString <span title="dom-fs-formTarget">formTarget</span>;
attribute DOMString <span title="dom-fe-name">name</span>;
attribute DOMString <span title="dom-button-type">type</span>;
attribute DOMString <span title="dom-button-value">value</span>;
readonly attribute boolean <span title="dom-cva-willValidate">willValidate</span>;
readonly attribute <span>ValidityState</span> <span title="dom-cva-validity">validity</span>;
readonly attribute DOMString <span title="dom-cva-validationMessage">validationMessage</span>;
boolean <span title="dom-cva-checkValidatity">checkValidity</span>();
void <span title="dom-cva-setCustomValidity">setCustomValidity</span>(in DOMString error);
readonly attribute <span>NodeList</span> <span title="dom-lfe-labels">labels</span>;
};</pre>
</dd>
</dl>
<p>The <code>button</code> element <span>represents</span> a
button. <span class="impl">If the element is not <span
title="concept-fe-disabled">disabled</span>, then the user agent
should allow the user to activate the button.</span></p>
<p>The element is a <span title="concept-button">button</span>.</p>
<p>The <dfn title="attr-button-type"><code>type</code></dfn>
attribute controls the behavior of the button when it is activated.
It is an <span>enumerated attribute</span>. The following table
lists the keywords and states for the attribute — the keywords
in the left column map to the states in the cell in the second
column on the same row as the keyword.</p>
<table>
<thead>
<tr>
<th> Keyword
<th> State
<th> Brief description
<tbody>
<tr>
<td><dfn title="attr-button-type-submit"><code>submit</code></dfn>
<td><span title="attr-button-type-submit-state">Submit Button</span>
<td>Submits the form.
<tr>
<td><dfn title="attr-button-type-reset"><code>reset</code></dfn>
<td><span title="attr-button-type-reset-state">Reset Button</span>
<td>Resets the form.
<tr>
<td><dfn title="attr-button-type-button"><code>button</code></dfn>
<td><span title="attr-button-type-button-state">Button</span>
<td>Does nothing.
</table>
<p>The <i>missing value default</i> is the <span
title="attr-button-type-submit-state">Submit Button</span>
state.</p>
<p>If the <code title="attr-button-type">type</code> attribute is in
the <span title="attr-button-type-submit-state">Submit Button</span>
state, the element is specifically a <span
title="concept-submit-button">submit button</span>.</p>
<div class="impl">
<p><strong>Constraint validation</strong>: If the <code
title="attr-button-type">type</code> attribute is in the <span
title="attr-button-type-reset-state">Reset Button</span> state or
the <span title="attr-button-type-button-state">Button</span> state,
the element is <span>barred from constraint validation</span>.</p>
<p>If the element is not <span
title="concept-fe-disabled">disabled</span>, the <span>activation
behavior</span> of the <code>button</code> element is to run the
steps defined in the following list for the current state of the
element's <code title="attr-button-type">type</code> attribute.</p>
<dl>
<dt> <dfn title="attr-button-type-submit-state">Submit Button</dfn> </dt>
<dd><p>If the element has a <span>form owner</span>, the element
must <span title="concept-form-submit">submit</span> the <span>form
owner</span> from the <code>button</code> element.</p></dd>
<dt> <dfn title="attr-button-type-reset-state">Reset Button</dfn> </dt>
<dd><p>If the element has a <span>form owner</span>, the element
must <span title="concept-form-reset">reset</span> the <span>form
owner</span>.</p></dd>
<dt> <dfn title="attr-button-type-button-state">Button</dfn>
<dd><p>Do nothing.</p></dd>
</dl>
</div>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>button</code> element with its
<span>form owner</span>. The <code title="attr-fe-name">name</code>
attribute represents the element's name. The <code
title="attr-fe-disabled">disabled</code> attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The <code title="attr-fe-autofocus">autofocus</code>
attribute controls focus. The <code
title="attr-fs-formaction">formaction</code>, <code
title="attr-fs-formenctype">formenctype</code>, <code
title="attr-fs-formmethod">formmethod</code>, <code
title="attr-fs-formnovalidate">formnovalidate</code>, and <code
title="attr-fs-formtarget">formtarget</code> attributes are
<span>attributes for form submission</span>.</p>
<p class="note">The <code
title="attr-fs-formnovalidate">formnovalidate</code> attribute can
be used to make submit buttons that do not trigger the constraint
validation.</p>
<p>The <dfn title="attr-button-value"><code>value</code></dfn>
attribute gives the element's value for the purposes of form
submission. The <code title="attr-button-value">value</code>
attribute must not be present unless the <code
title="attr-fae-form">form</code> attribute is present. The
element's <span title="concept-fe-value">value</span> is the value
of the element's <code title="attr-button-value">value</code>
attribute, if there is one, or the empty string otherwise.</p>
<p class="note">A button (and its value) is only included in the
form submission if the button itself was used to initiate the form
submission.</p>
<div class="impl">
<p>The <dfn title="dom-button-value"><code>value</code></dfn> and
<dfn title="dom-button-type"><code>type</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name.</p>
<p>The <code title="dom-cva-willValidate">willValidate</code>, <code
title="dom-cva-validity">validity</code>, and <code
title="dom-cva-validationMessage">validationMessage</code>
attributes, and the <code
title="dom-cva-checkValidatity">checkValidity()</code> and <code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
methods, are part of the <span>constraint validation API</span>. The
<code title="dom-lfe-labels">labels</code> attribute provides a list
of the element's <code>label</code>s.</p>
</div>
<div class="example">
<p>The following button is labeled "Show hint" and pops up a dialog
box when activated:</p>
<pre><button type=button
onclick="alert('This 15-20 minute piece was composed by George Gershwin.')">
Show hint
</button></pre>
</div>
<h4>The <dfn><code>select</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dd><span title="category-listed">Listed</span>, <span title="category-label">labelable</span>, <span title="category-submit">submittable</span>, and <span title="category-reset">resettable</span> <span>form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>option</code> or <code>optgroup</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-fe-autofocus">autofocus</code></dd>
<dd><code title="attr-fe-disabled">disabled</code></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-select-multiple">multiple</code></dd>
<dd><code title="attr-fe-name">name</code></dd>
<dd><code title="attr-select-size">size</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-fe-autofocus">autofocus</span>;
attribute boolean <span title="dom-fe-disabled">disabled</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
attribute boolean <span title="dom-select-multiple">multiple</span>;
attribute DOMString <span title="dom-fe-name">name</span>;
attribute unsigned long <span title="dom-select-size">size</span>;
readonly attribute DOMString <span title="dom-select-type">type</span>;
readonly attribute <span>HTMLOptionsCollection</span> <span title="dom-select-options">options</span>;
attribute unsigned long <span title="dom-select-length">length</span>;
caller getter any <span title="dom-select-item">item</span>(in unsigned long index);
caller getter any <span title="dom-select-namedItem">namedItem</span>(in DOMString name);
void <span title="dom-select-add">add</span>(in <span>HTMLElement</span> element, in optional <span>HTMLElement</span> before);
void <span title="dom-select-add">add</span>(in <span>HTMLElement</span> element, in long before);
void <span title="dom-select-remove">remove</span>(in long index);
readonly attribute <span>HTMLCollection</span> <span title="dom-select-selectedOptions">selectedOptions</span>;
attribute long <span title="dom-select-selectedIndex">selectedIndex</span>;
attribute DOMString <span title="dom-select-value">value</span>;
readonly attribute boolean <span title="dom-cva-willValidate">willValidate</span>;
readonly attribute <span>ValidityState</span> <span title="dom-cva-validity">validity</span>;
readonly attribute DOMString <span title="dom-cva-validationMessage">validationMessage</span>;
boolean <span title="dom-cva-checkValidatity">checkValidity</span>();
void <span title="dom-cva-setCustomValidity">setCustomValidity</span>(in DOMString error);
readonly attribute <span>NodeList</span> <span title="dom-lfe-labels">labels</span>;
};</pre>
</dd>
</dl>
<!-- Proposals for v2:
* <select value=""> as an alternative to <option selected>
http://developers.slashdot.org/comments.pl?sid=426306&cid=22142072
<Philip`> http://www.ipiao.com.cn/ does <select size="1" name="to"><script>City_Default="PEK"</script><SCRIPT language=javascript
src="/js/flightcity.js"></SCRIPT></select> which is the kind of thing that could be much simpler with <select value="PEK">
* a way to make the <select> not have a default value at all (ack
or to have a "placeholer" like value that doesn't count as a value being selected but shows a prompt until a value is selected
* once we can have no default, a way to require="" a value.
ack Weston Ruter: http://weston.ruter.net/projects/test-cases/html-select-element/
q.v. http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2008-November/017583.html
-->
<p>The <code>select</code> element represents a control for
selecting amongst a set of options.</p>
<p>The <dfn title="attr-select-multiple"><code>multiple</code></dfn>
attribute is a <span>boolean attribute</span>. If the attribute is
present, then the <code>select</code> element
<span>represents</span> a control for selecting zero or more options
from the <span title="concept-select-option-list">list of
options</span>. If the attribute is absent, then the
<code>select</code> element <span>represents</span> a control for
selecting a single option from the <span
title="concept-select-option-list">list of options</span>.</p>
<p>The <dfn title="concept-select-option-list">list of options</dfn>
for a <code>select</code> element consists of all the
<code>option</code> element children of the <code>select</code>
element, and all the <code>option</code> element children of all the
<code>optgroup</code> element children of the <code>select</code>
element, in <span>tree order</span>.</p>
<p>The <dfn title="attr-select-size"><code>size</code></dfn>
attribute gives the number of options to show to the user. The <code
title="attr-input-size">size</code> attribute, if specified, must
have a value that is a <span>valid non-negative integer</span>
greater than zero. If the <code
title="attr-select-multiple">multiple</code> attribute is present,
then the <code title="attr-input-size">size</code> attribute's
default value is 4. If the <code
title="attr-select-multiple">multiple</code> attribute is absent,
then the <code title="attr-input-size">size</code> attribute's
default value is 1.</p>
<div class="impl">
<p>If the <code title="attr-select-multiple">multiple</code>
attribute is absent, and the element is not <span
title="concept-fe-disabled">disabled</span>, then the user agent
should allow the user to pick an <code>option</code> element in its
<span title="concept-select-option-list">list of options</span> that
is itself not <span
title="concept-option-disabled">disabled</span>. Upon this
<code>option</code> element being <dfn
title="concept-select-pick">picked</dfn> (either through a click, or
through unfocusing the element after changing its value, or through
a <span title="option-command">menu command</span>, or through any
other mechanism), and before the relevant user interaction event
<!-- interaction event spec point --> is queued (e.g. before the
<span title="event-click">click</span> event), the user agent must
set the <span
title="concept-option-selectedness">selectedness</span> of the
picked <code>option</code> element to true and then <span>queue a
task</span> to <span>fire a simple event</span> that bubbles named
<code title="event-change">change</code> at the <code>select</code>
element, using the <span>user interaction task source</span> as the
task source, then <span>broadcast <code
title="event-formchange">formchange</code> events</span> at the
element's <span>form owner</span>.</p>
<p>If the <code title="attr-select-multiple">multiple</code>
attribute is absent, whenever an <code>option</code> element in the
<code>select</code> element's <span
title="concept-select-option-list">list of options</span> has its
<span title="concept-option-selectedness">selectedness</span> set to
true, and whenever an <code>option</code> element with its <span
title="concept-option-selectedness">selectedness</span> set to true
is added to the <code>select</code> element's <span
title="concept-select-option-list">list of options</span>, the user
agent must set the <span
title="concept-option-selectedness">selectedness</span> of all the
other <code>option</code> element in its <span
title="concept-select-option-list">list of options</span> to
false.</p>
<p>If the <code title="attr-select-multiple">multiple</code>
attribute is absent, whenever there are no <code>option</code>
elements in the <code>select</code> element's <span
title="concept-select-option-list">list of options</span> that have
their <span title="concept-option-selectedness">selectedness</span>
set to true, the user agent must set the <span
title="concept-option-selectedness">selectedness</span> of the first
<code>option</code> element in the <span
title="concept-select-option-list">list of options</span> in
<span>tree order</span> that is not <span
title="concept-option-disabled">disabled</span>, if any, to
true.</p>
<p>If the <code title="attr-select-multiple">multiple</code>
attribute is present, and the element is not <span
title="concept-fe-disabled">disabled</span>, then the user agent
should allow the user to <dfn
title="concept-select-toggle">toggle</dfn> the <span
title="concept-option-selectedness">selectedness</span> of the
<code>option</code> elements in its <span
title="concept-select-option-list">list of options</span> that are
themselves not <span title="concept-option-disabled">disabled</span>
(either through a click, or through a <span
title="option-command">menu command</span>, or any other
mechanism). Upon the <span
title="concept-option-selectedness">selectedness</span> of one or
more <code>option</code> elements being changed by the user, and
before the relevant user interaction event <!-- interaction event
spec point --> is queued (e.g. before a related <span
title="event-click">click</span> event), the user agent must
<span>queue a task</span> to <span>fire a simple event</span> that
bubbles named <code title="event-change">change</code> at the
<code>select</code> element, using the <span>user interaction task
source</span> as the task source, then <span>broadcast <code
title="event-formchange">formchange</code> events</span> at the
element's <span>form owner</span>.</p>
<p>The <span title="concept-form-reset-control">reset
algorithm</span> for <code>select</code> elements is to go through
all the <code>option</code> elements in the element's <span
title="concept-select-option-list">list of options</span>, and set
their <span title="concept-option-selectedness">selectedness</span>
to true if the <code>option</code> element has a <code
title="attr-option-selected">selected</code> attribute, and false
otherwise.</p>
</div>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>select</code> element with its
<span>form owner</span>. The <code title="attr-fe-name">name</code>
attribute represents the element's name. The <code
title="attr-fe-disabled">disabled</code> attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The <code title="attr-fe-autofocus">autofocus</code>
attribute controls focus.</p>
<dl class="domintro">
<dt><var title="">select</var> . <code title="dom-select-type">type</code></dt>
<dd>
<p>Returns "<code title="">select-multiple</code>" if the element
has a <code title="attr-select-multiple">multiple</code>
attribute, and "<code title="">select-one</code>"
otherwise.</p>
</dd>
<dt><var title="">select</var> . <code title="dom-select-options">options</code></dt>
<dd>
<p>Returns an <code>HTMLOptionsCollection</code> of the <span
title="concept-select-option-list">list of options</span>.</p>
</dd>
<dt><var title="">select</var> . <code title="dom-select-length">length</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the number of elements in the <span title="concept-select-option-list">list of options</span>.</p>
<p>When set to a smaller number, truncates the number of <code>option</code> elements in the <code>select</code>.</p>
<p>When set to a greater number, adds new blank <code>option</code> elements to the <code>select</code>.</p>
</dd>
<dt><var title="">element</var> = <var title="">select</var> . <code title="dom-select-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">select</var>[<var title="">index</var>]</dt>
<dt><var title="">select</var>(<var title="">index</var>)</dt>
<dd>
<p>Returns the item with index <var title="">index</var> from the <span title="concept-select-option-list">list of options</span>. The items are sorted in <span>tree order</span>.</p>
<p>Returns null if <var title="">index</var> is out of range.</p>
</dd>
<dt><var title="">element</var> = <var title="">select</var> . <code title="dom-select-item">namedItem</code>(<var title="">name</var>)</dt>
<dt><var title="">select</var>[<var title="">name</var>]</dt>
<dt><var title="">select</var>(<var title="">name</var>)</dt>
<dd>
<p>Returns the item with ID or <code title="attr-option-name">name</code> <var title="">name</var> from the <span title="concept-select-option-list">list of options</span>.</p>
<p>If there are multiple matching items, then a <code>NodeList</code> object containing all those elements is returned.</p>
<p>Returns null if no element with that ID could be found.</p>
</dd>
<dt><var title="">select</var> . <code title="dom-select-add">add</code>(<var title="">element</var> [, <var title="">before</var> ])</dt>
<dd>
<p>Inserts <var title="">element</var> before the node given by <var title="">before</var>.</p>
<p>The <var title="">before</var> argument can be a number, in
which case <var title="">element</var> is inserted before the item
with that number, or an element from the <span
title="concept-select-option-list">list of options</span>, in
which case <var title="">element</var> is inserted before that
element.</p>
<p>If <var title="">before</var> is omitted, null, or a number out
of range, then <var title="">element</var> will be added at the
end of the list.</p>
<p>This method will throw a <code>HIERARCHY_REQUEST_ERR</code>
exception if <var title="">element</var> is an ancestor of the
element into which it is to be inserted. If <var
title="">element</var> is not an <code>option</code> or
<code>optgroup</code> element, then the method does nothing.</p>
</dd>
<dt><var title="">select</var> . <code title="dom-select-selectedOptions">selectedOptions</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <span
title="concept-select-option-list">list of options</span> that are
selected.</p>
</dd>
<dt><var title="">select</var> . <code title="dom-select-selectedIndex">selectedIndex</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the index of the first selected item, if any, or
−1 if there is no selected item.</p>
<p>Can be set, to change the selection.</p>
</dd>
<dt><var title="">select</var> . <code title="dom-select-value">value</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the <span title="concept-fe-value">value</span> of the
first selected item, if any, or the empty string if there is no
selected item.</p>
<p>Can be set, to change the selection.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-select-type"><code>type</code></dfn> IDL
attribute, on getting, must return the string "<code
title="">select-one</code>" if the <code
title="attr-select-multiple">multiple</code> attribute is absent,
and the string "<code title="">select-multiple</code>" if the <code
title="attr-select-multiple">multiple</code> attribute is
present.</p>
<p>The <dfn title="dom-select-options"><code>options</code></dfn>
IDL attribute must return an <code>HTMLOptionsCollection</code>
rooted at the <code>select</code> node, whose filter matches the
elements in the <span title="concept-select-option-list">list of
options</span>.</p>
<p>The <code title="dom-select-options">options</code> collection is
also mirrored on the <code>HTMLSelectElement</code> object. The
<span>indices of the supported indexed properties</span> at any
instant are the indices supported by the object returned by the
<code title="dom-select-options">options</code> attribute at that
instant. The <span>names of the supported named properties</span> at
any instant are the names supported by the object returned by the
<code title="dom-select-options">options</code> attribute at that
instant.</p>
<p>The <dfn title="dom-select-length"><code>length</code></dfn> IDL
attribute must return the number of nodes <span title="represented
by the collection">represented</span> by the <code
title="dom-select-options">options</code> collection. On setting, it
must act like the attribute of the same name on the <code
title="dom-select-options">options</code> collection.</p>
<p>The <dfn title="dom-select-item"><code>item(<var
title="">index</var>)</code></dfn> method must return the value
returned by the method of the same name on the <code
title="dom-select-options">options</code> collection, when invoked
with the same argument.</p>
<p>The <dfn title="dom-select-namedItem"><code>namedItem(<var
title="">name</var>)</code></dfn> method must return the value
returned by the method of the same name on the <code
title="dom-select-options">options</code> collection, when invoked
with the same argument.</p>
<p>Similarly, the <dfn
title="dom-select-add"><code>add()</code></dfn> and <dfn
title="dom-select-remove"><code>remove()</code></dfn> methods must
act like their namesake methods on that same <code
title="dom-select-options">options</code> collection.</p>
<p>The <dfn
title="dom-select-selectedOptions"><code>selectedOptions</code></dfn>
IDL attribute must return an <code>HTMLCollection</code> rooted at
the <code>select</code> node, whose filter matches the elements in
the <span title="concept-select-option-list">list of options</span>
that have their <span
title="concept-option-selectedness">selectedness</span> set to
true.</p>
<p>The <dfn
title="dom-select-selectedIndex"><code>selectedIndex</code></dfn>
IDL attribute, on getting, must return the <span
title="concept-option-index">index</span> of the first
<code>option</code> element in the <span
title="concept-select-option-list">list of options</span> in
<span>tree order</span> that has its <span
title="concept-option-selectedness">selectedness</span> set to true,
if any. If there isn't one, then it must return −1.</p>
<p>On setting, the <code
title="dom-select-selectedIndex">selectedIndex</code> attribute must
set the <span
title="concept-option-selectedness">selectedness</span> of all the
<code>option</code> elements in the <span
title="concept-select-option-list">list of options</span> to false,
and then the <code>option</code> element in the <span
title="concept-select-option-list">list of options</span> whose
<span title="concept-option-index">index</span> is the given new
value, if any, must have its <span
title="concept-option-selectedness">selectedness</span> set to
true.</p>
<p>The <dfn title="dom-select-value"><code>value</code></dfn> IDL
attribute, on getting, must return the <span
title="concept-option-value">value</span> of the first
<code>option</code> element in the <span
title="concept-select-option-list">list of options</span> in
<span>tree order</span> that has its <span
title="concept-option-selectedness">selectedness</span> set to true,
if any. If there isn't one, then it must return the empty
string.</p>
<p>On setting, the <code title="dom-select-value">value</code>
attribute must set the <span
title="concept-option-selectedness">selectedness</span> of all the
<code>option</code> elements in the <span
title="concept-select-option-list">list of options</span> to false,
and then first the <code>option</code> element in the <span
title="concept-select-option-list">list of options</span>, in
<span>tree order</span>, whose <span
title="concept-option-value">value</span> is equal to the given new
value, if any, must have its <span
title="concept-option-selectedness">selectedness</span> set to
true.</p>
<p>The <dfn title="dom-select-multiple"><code>multiple</code></dfn>
and <dfn title="dom-select-size"><code>size</code></dfn> IDL
attributes must <span>reflect</span> the respective content
attributes of the same name. The <code
title="dom-select-size">size</code> IDL attribute <span>limited to
only non-negative numbers greater than zero</span>.</p>
<p>The <code title="dom-cva-willValidate">willValidate</code>, <code
title="dom-cva-validity">validity</code>, and <code
title="dom-cva-validationMessage">validationMessage</code>
attributes, and the <code
title="dom-cva-checkValidatity">checkValidity()</code> and <code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
methods, are part of the <span>constraint validation API</span>. The
<code title="dom-lfe-labels">labels</code> attribute provides a list
of the element's <code>label</code>s.</p>
</div>
<div class="example">
<p>The following example shows how a <code>select</code> element
can be used to offer the user with a set of options from which the
user can select a single option. The default option is
preselected</p>
<pre><p>
<label for="unittype">Select unit type:</label>
<select id="unittype" name="unittype">
<option value="1"> Miner </option>
<option value="2"> Puffer </option>
<option value="3" selected> Snipey </option>
<option value="4"> Max </option>
<option value="5"> Firebot </option>
</select>
</p></pre>
</div>
<div class="example">
<p>Here, the user is offered a set of options from which he can
select any number. By default, all five options are selected.</p>
<pre><p>
<label for="allowedunits">Select unit types to enable on this map:</label>
<select id="allowedunits" name="allowedunits" multiple>
<option value="1" selected> Miner </option>
<option value="2" selected> Puffer </option>
<option value="3" selected> Snipey </option>
<option value="4" selected> Max </option>
<option value="5" selected> Firebot </option>
</select>
</p></pre>
</div>
<h4>The <dfn><code>datalist</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Either: <span>phrasing content</span>.</dd>
<dd>Or: Zero or more <code>option</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLDataListElement</dfn> : <span>HTMLElement</span> {
readonly attribute <span>HTMLCollection</span> <span title="dom-datalist-options">options</span>;
};</pre>
</dd>
</dl>
<p>The <code>datalist</code> element represents a set of
<code>option</code> elements that represent predefined options for
other controls. The contents of the element represents fallback
content for legacy user agents, intermixed with <code>option</code>
elements that represent the predefined options. In the rendering,
the <code>datalist</code> element <span>represents</span>
nothing<span class="impl"> and it, along with its children, should
be hidden</span>.</p>
<p>The <code>datalist</code> element is hooked up to an
<code>input</code> element using the <code
title="attr-input-list">list</code> attribute on the
<code>input</code> element. <!-- v2DATAGRID The
<code>datalist</code> element can also be used with a
<code>datagrid</code> element, as the source of autocompletion hints
for <code title="datagrid-type-editable">editable</code>
cells. --></p>
<p>Each <code>option</code> element that is a descendant of the
<code>datalist</code> element, that is not <span
title="concept-option-disabled">disabled</span>, and whose <span
title="concept-option-value">value</span> is a string that isn't the
empty string, represents a suggestion. Each suggestion has a <span
title="concept-option-value">value</span> and a <span
title="concept-option-label">label</span>.
<dl class="domintro">
<dt><var title="">datalist</var> . <code title="dom-datalist-options">options</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the <code>options</code> elements of the table.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-datalist-options"><code>options</code></dfn>
IDL attribute must return an <code>HTMLCollection</code> rooted at
the <code>datalist</code> node, whose filter matches
<code>option</code> elements.</p>
<p><strong>Constraint validation</strong>: If an element has a
<code>datalist</code> element ancestor, it is <span>barred from
constraint validation</span>.</p>
</div>
<h4>The <dfn><code>optgroup</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>select</code> element.</dd>
<dt>Content model:</dt>
<dd>Zero or more <code>option</code> elements.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-optgroup-disabled">disabled</code></dd>
<dd><code title="attr-optgroup-label">label</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLOptGroupElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-optgroup-disabled">disabled</span>;
attribute DOMString <span title="dom-optgroup-label">label</span>;
};</pre>
</dd>
</dl>
<!-- v2: make optgroups selectable if they have a value. -->
<p>The <code>optgroup</code> element <span>represents</span> a group of
<code>option</code> elements with a common label.</p>
<p>The element's group of <code>option</code> elements consists of
the <code>option</code> elements that are children of the
<code>optgroup</code> element.</p>
<Div class="impl">
<p>When showing <code>option</code> elements in <code>select</code>
elements, user agents should show the <code>option</code> elements
of such groups as being related to each other and separate from
other <code>option</code> elements.</p>
</div>
<p>The <dfn
title="attr-optgroup-disabled"><code>disabled</code></dfn> attribute
is a <span>boolean attribute</span> and can be used to <span
title="concept-option-disabled">disable</span> a group of
<code>option</code> elements together.</p>
<p>The <dfn title="attr-optgroup-label"><code>label</code></dfn>
attribute must be specified. Its value gives the name of the group,
for the purposes of the user interface. <span class="impl">User
agents should use this attribute's value when labelling the group of
<code>option</code> elements in a <code>select</code>
element.</span></p>
<div class="impl">
<p>The <dfn
title="dom-optgroup-disabled"><code>disabled</code></dfn> and <dfn
title="dom-optgroup-label"><code>label</code></dfn> attributes must
<span>reflect</span> the respective content attributes of the same
name.</p>
</div>
<div class="example">
<p>The following snippet shows how a set of lessons from three
courses could be offered in a <code>select</code> drop-down
widget:</p>
<pre><form action="courseselector.dll" method="get">
<p>Which course would you like to watch today?
<p><label>Course:
<select name="c">
<optgroup label="8.01 Physics I: Classical Mechanics">
<option value="8.01.1">Lecture 01: Powers of Ten
<option value="8.01.2">Lecture 02: 1D Kinematics
<option value="8.01.3">Lecture 03: Vectors
<optgroup label="8.02 Electricity and Magnestism">
<option value="8.02.1">Lecture 01: What holds our world together?
<option value="8.02.2">Lecture 02: Electric Field
<option value="8.02.3">Lecture 03: Electric Flux
<optgroup label="8.03 Physics III: Vibrations and Waves">
<option value="8.03.1">Lecture 01: Periodic Phenomenon
<option value="8.03.2">Lecture 02: Beats
<option value="8.03.3">Lecture 03: Forced Oscillations with Damping
</select>
</label>
<p><input type=submit value="▶ Play">
</form></pre>
</div>
<h4>The <dfn><code>option</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd>None.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>As a child of a <code>select</code> element.</dd>
<dd>As a child of a <code>datalist</code> element.</dd>
<dd>As a child of an <code>optgroup</code> element.</dd>
<dt>Content model:</dt>
<dd><span title="text content">Text</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-option-disabled">disabled</code></dd>
<dd><code title="attr-option-label">label</code></dd>
<dd><code title="attr-option-selected">selected</code></dd>
<dd><code title="attr-option-value">value</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">[NamedConstructor=<span title="dom-option">Option</span>(),
NamedConstructor=<span title="dom-option-t">Option</span>(in DOMString text),
NamedConstructor=<span title="dom-option-tv">Option</span>(in DOMString text, in DOMString value),
NamedConstructor=<span title="dom-option-tvd">Option</span>(in DOMString text, in DOMString value, in boolean defaultSelected),
NamedConstructor=<span title="dom-option-tvds">Option</span>(in DOMString text, in DOMString value, in boolean defaultSelected, in boolean selected)]
interface <dfn>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-option-disabled">disabled</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-option-form">form</span>;
attribute DOMString <span title="dom-option-label">label</span>;
attribute boolean <span title="dom-option-defaultSelected">defaultSelected</span>;
attribute boolean <span title="dom-option-selected">selected</span>;
attribute DOMString <span title="dom-option-value">value</span>;
attribute DOMString <span title="dom-option-text">text</span>;
readonly attribute long <span title="dom-option-index">index</span>;
};</pre>
</dd>
</dl>
<p>The <code>option</code> element <span>represents</span> an option
in a <code>select</code> element or as part of a list of suggestions
in a <code>datalist</code> element.</p>
<p>The <dfn title="attr-option-disabled"><code>disabled</code></dfn>
attribute is a <span>boolean attribute</span>. An
<code>option</code> element is <dfn
title="concept-option-disabled">disabled</dfn> if its <code
title="attr-option-disabled">disabled</code> attribute is present or
if it is a child of an <code>optgroup</code> element whose <code
title="attr-optgroup-disabled">disabled</code> attribute is
present.</p>
<div class="impl">
<p>An <code>option</code> element that is <span
title="attr-option-disabled">disabled</span> must prevent any <code
title="event-click">click</code> events that are <span title="queue
a task">queued</span> on the <span>user interaction task
source</span> from being dispatched on the element.</p>
</div>
<p>The <dfn title="attr-option-label"><code>label</code></dfn>
attribute provides a label for element. The <dfn
title="concept-option-label">label</dfn> of an <code>option</code>
element is the value of the <code
title="attr-option-label">label</code> attribute, if there is one,
or the <code>textContent</code> of the element, if there isn't.</p>
<p>The <dfn title="attr-option-value"><code>value</code></dfn>
attribute provides a value for element. The <dfn
title="concept-option-value">value</dfn> of an <code>option</code>
element is the value of the <code
title="attr-option-value">value</code> attribute, if there is one,
or the <code>textContent</code> of the element, if there isn't.</p>
<p>The <dfn title="attr-option-selected"><code>selected</code></dfn>
attribute represents the default <span
title="concept-option-selectedness">selectedness</span> of the
element.</p>
<div class="impl">
<p>The <dfn title="concept-option-selectedness">selectedness</dfn>
of an <code>option</code> element is a boolean state, initially
false. If the element is <span
title="concept-option-disabled">disabled</span>, then the element's
<span title="concept-option-selectedness">selectedness</span> is
always false and cannot be set to true. Except where otherwise
specified, when the element is created, its <span
title="concept-option-selectedness">selectedness</span> must be set
to true if the element has a <code
title="attr-option-selected">selected</code> attribute. Whenever an
<code>option</code> element's <code
title="attr-option-selected">selected</code> attribute is added, its
<span title="concept-option-selectedness">selectedness</span> must
be set to true.</p>
<p class="note">The <code title="dom-option-tvd">Option()</code>
constructor with three or fewer arguments overrides the initial
state of the <span
title="concept-option-selectedness">selectedness</span> state to
always be false even if the third argument is true (implying that a
<code title="attr-option-selected">selected</code> attribute is to
be set). The fourth argument can be used to explicitly set the
initial <span
title="concept-option-selectedness">selectedness</span> state when
using the constructor.</p>
<p>An <code>option</code> element's <dfn
title="concept-option-index">index</dfn> is the number of
<code>option</code> element that are in the same <span
title="concept-select-option-list">list of options</span> but that
come before it in <span>tree order</span>. If the
<code>option</code> element is not in a <span
title="concept-select-option-list">list of options</span>, then the
<code>option</code> element's <span
title="concept-option-index">index</span> is zero.</p>
</div>
<dl class="domintro">
<dt><var title="">option</var> . <code title="dom-option-selected">selected</code></dt>
<dd>
<p>Returns true if the element is selected, and false otherwise.</p>
</dd>
<dt><var title="">option</var> . <code title="dom-option-index">index</code></dt>
<dd>
<p>Returns the index of the element in its <code>select</code>
element's <code title="dom-select-options">options</code>
list.</p>
</dd>
<dt><var title="">option</var> . <code title="dom-option-form">form</code></dt>
<dd>
<p>Returns the element's <code>form</code> element, if any, or
null otherwise.</p>
</dd>
<dt><var title="">option</var> = new <code title="dom-option">Option</code>( [ <var title="">text</var> [, <var title="">value</var> [, <var title="">defaultSelected</var> [, <var title="">selected</var> ] ] ] ] )</dt>
<dd>
<p>Returns a new <code>option</code> element.</p>
<p>The <var title="">text</var> argument sets the contents of the element.</p>
<p>The <var title="">value</var> argument sets the <code title="attr-option-value">value</code> attribute.</p>
<p>The <var title="">defaultSelected</var> argument sets the <code title="attr-option-selected">selected</code> attribute.</p>
<p>The <var title="">selected</var> argument sets whether or not the element is selected. If it is omitted, even if the <var title="">defaultSelected</var> argument is true, the element is not selected.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-option-disabled"><code>disabled</code></dfn>
and <dfn title="dom-option-label"><code>label</code></dfn> IDL
attributes must <span>reflect</span> the respective content
attributes of the same name. The <dfn
title="dom-option-defaultSelected"><code>defaultSelected</code></dfn>
IDL attribute must <span>reflect</span> the <code
title="attr-option-selected">selected</code> content attribute.</p>
<p>The <dfn title="dom-option-value"><code>value</code></dfn> IDL
attribute, on getting, must return the value of the element's <code
title="attr-option-value">value</code> content attribute, if it has
one, or else the value of the element's <code>textContent</code> IDL
attribute. On setting, the element's <code
title="attr-option-value">value</code> content attribute must be set
to the new value.</p>
<p>The <dfn title="dom-option-selected"><code>selected</code></dfn>
IDL attribute must return true if the element's <span
title="concept-option-selectedness">selectedness</span> is true, and
false otherwise.</p>
<p>The <dfn title="dom-option-index"><code>index</code></dfn> IDL
attribute must return the element's <span
title="concept-option-index">index</span>.</p>
<p>The <dfn title="dom-option-text"><code>text</code></dfn> IDL
attribute, on getting, must return the same value as the
<code>textContent</code> IDL attribute on the element, and on
setting, must act as if the <code>textContent</code> IDL attribute
on the element had been set to the new value.</p>
<p>The <dfn title="dom-option-form"><code>form</code></dfn> IDL
attribute's behavior depends on whether the <code>option</code>
element is in a <code>select</code> element or not. If the
<code>option</code> has a <code>select</code> element as its parent,
or has a <code>colgroup</code> element as its parent and that
<code>colgroup</code> element has a <code>select</code> element as
its parent, then the <code title="dom-option-form">form</code> IDL
attribute must return the same value as the <code
title="dom-fae-form">form</code> IDL attribute on that
<code>select</code> element. Otherwise, it must return null.</p>
<p>Several constructors are provided for creating
<code>HTMLOptionElement</code> objects (in addition to the factory
methods from DOM Core such as <code
title="">createElement()</code>): <dfn
title="dom-option"><code>Option()</code></dfn>, <dfn
title="dom-option-t"><code>Option(<var
title="">text</var>)</code></dfn>, <dfn
title="dom-option-tv"><code>Option(<var title="">text</var>, <var
title="">value</var>)</code></dfn>, <dfn
title="dom-option-tvd"><code>Option(<var title="">text</var>, <var
title="">value</var>, <var
title="">defaultSelected</var>)</code></dfn>, and <dfn
title="dom-option-tvds"><code>Option(<var title="">text</var>, <var
title="">value</var>, <var title="">defaultSelected</var>, <var
title="">selected</var>)</code></dfn>. When invoked as constructors,
these must return a new <code>HTMLOptionElement</code> object (a new
<code>option</code> element). If the <var title="">text</var>
argument is present, the new object must have as its only child a
<code>Node</code> with node type <code title="">TEXT_NODE</code> (3)
whose data is the value of that argument<!-- we mention TEXT_NODE
and all that explicitly here because we redefine "text node" in this
spec to also include CDATA sections -->. If the <var
title="">value</var> argument is present, the new object must have a
<code title="attr-option-value">value</code> attribute set with the
value of the argument as its value. If the <var
title="">defaultSelected</var> argument is present and true, the new
object must have a <code
title="attr-option-selected">selected</code> attribute set with no
value. If the <var title="">selected</var> argument is present and
true, the new object must have its <span
title="concept-option-selectedness">selectedness</span> set to true;
otherwise the fourth argument is absent or false, and the <span
title="concept-option-selectedness">selectedness</span> must be set
to false, even if the <var title="">defaultSelected</var> argument
is present and true. The element's document must be the <span>active
document</span> of the <span>browsing context</span> of the
<code>Window</code> object on which the interface object of the
invoked constructor is found.</p>
</div>
<h4>The <dfn><code>textarea</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dd><span title="category-listed">Listed</span>, <span title="category-label">labelable</span>, <span title="category-submit">submittable</span>, and <span title="category-reset">resettable</span> <span>form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span title="text content">Text</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-fe-autofocus">autofocus</code></dd>
<dd><code title="attr-textarea-cols">cols</code></dd>
<dd><code title="attr-fe-disabled">disabled</code></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-textarea-maxlength">maxlength</code></dd>
<dd><code title="attr-fe-name">name</code></dd>
<dd><code title="attr-textarea-placeholder">placeholder</code></dd>
<dd><code title="attr-textarea-readonly">readonly</code></dd>
<dd><code title="attr-textarea-required">required</code></dd>
<dd><code title="attr-textarea-rows">rows</code></dd>
<dd><code title="attr-textarea-wrap">wrap</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLTextAreaElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-fe-autofocus">autofocus</span>;
attribute unsigned long <span title="dom-textarea-cols">cols</span>;
attribute boolean <span title="dom-fe-disabled">disabled</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
attribute long <span title="dom-textarea-maxLength">maxLength</span>;
attribute DOMString <span title="dom-fe-name">name</span>;
attribute DOMString <span title="dom-textarea-placeholder">placeholder</span>;
attribute boolean <span title="dom-textarea-readOnly">readOnly</span>;
attribute boolean <span title="dom-textarea-required">required</span>;
attribute unsigned long <span title="dom-textarea-rows">rows</span>;
attribute DOMString <span title="dom-textarea-wrap">wrap</span>;
readonly attribute DOMString <span title="dom-textarea-type">type</span>;
attribute DOMString <span title="dom-textarea-defaultValue">defaultValue</span>;
attribute DOMString <span title="dom-textarea-value">value</span>;
readonly attribute unsigned long <span title="dom-textarea-textLength">textLength</span>;
readonly attribute boolean <span title="dom-cva-willValidate">willValidate</span>;
readonly attribute <span>ValidityState</span> <span title="dom-cva-validity">validity</span>;
readonly attribute DOMString <span title="dom-cva-validationMessage">validationMessage</span>;
boolean <span title="dom-cva-checkValidatity">checkValidity</span>();
void <span title="dom-cva-setCustomValidity">setCustomValidity</span>(in DOMString error);
readonly attribute <span>NodeList</span> <span title="dom-lfe-labels">labels</span>;
void <span title="dom-textarea/input-select">select</span>();
attribute unsigned long <span title="dom-textarea/input-selectionStart">selectionStart</span>;
attribute unsigned long <span title="dom-textarea/input-selectionEnd">selectionEnd</span>;
void <span title="dom-textarea/input-setSelectionRange">setSelectionRange</span>(in unsigned long start, in unsigned long end);
};</pre>
</dd>
</dl>
<p>The <code>textarea</code> element <span>represents</span> a
multiline plain text edit control<span class="impl"> for the
element's <dfn title="concept-textarea-raw-value">raw
value</dfn></span>. The contents of the control represent the
control's default value.</p>
<div class="impl">
<p>The <span title="concept-textarea-raw-value">raw value</span> of
a <code>textarea</code> control must be initially the empty
string.</p>
</div>
<p>The <dfn
title="attr-textarea-readonly"><code>readonly</code></dfn> attribute
is a <span>boolean attribute</span> used to control whether the text
can be edited by the user or not.</p>
<div class="impl">
<p><strong>Constraint validation</strong>: If the <code
title="attr-textarea-readonly">readonly</code> attribute is
specified on a <code>textarea</code> element, the element is
<span>barred from constraint validation</span>.</p>
<p>A <code>textarea</code> element is <dfn
title="concept-textarea-mutable">mutable</dfn> if it is neither
<span title="concept-fe-disabled">disabled</span> nor has a <code
title="attr-textarea-readonly">readonly</code> attribute
specified.</p>
<p>When a <code>textarea</code> is <span
title="concept-textarea-mutable">mutable</span>, its <span
title="concept-textarea-raw-value">raw value</span> should be
editable by the user. Any time the user causes the element's <span
title="concept-textarea-raw-value">raw value</span> to change, the
user agent must <span>queue a task</span> to <span>fire a simple
event</span> that bubbles named <code
title="event-input">input</code> at the <code>textarea</code>
element, then <span>broadcast <code
title="event-forminput">forminput</code> events</span> at the
<code>textarea</code> element's <span>form owner</span>. User agents
may wait for a suitable break in the user's interaction before
queuing the task; for example, a user agent could wait for the user
to have not hit a key for 100ms, so as to only fire the event when
the user pauses, instead of continuously for each keystroke.</p>
<!-- same text is present in the <input> section -->
<p>A <code>textarea</code> element has a <dfn
title="concept-textarea-dirty">dirty value flag</dfn>, which must be
initially set to false, and must be set to true whenever the user
interacts with the control in a way that changes the <span
title="concept-textarea-raw-value">raw value</span>.</p>
<p>When the <code>textarea</code> element's <code>textContent</code>
IDL attribute changes value, if the element's <span
title="concept-textarea-dirty">dirty value flag</span> is false,
then the element's <span title="concept-textarea-raw-value">raw
value</span> must be set to the value of the element's
<code>textContent</code> IDL attribute.</p>
<p>The <span title="concept-form-reset-control">reset
algorithm</span> for <code>textarea</code> elements is to set the
element's <span title="concept-textarea-raw-value">value</span> to
the value of the element's <code>textContent</code> IDL
attribute.</p>
</div>
<p>The <dfn title="attr-textarea-cols"><code>cols</code></dfn>
attribute specifies the expected maximum number of characters per
line. If the <code title="attr-textarea-cols">cols</code> attribute
is specified, its value must be a <span>valid non-negative
integer</span> greater than zero. <span class="impl">If applying the
<span>rules for parsing non-negative integers</span> to the
attribute's value results in a number greater than zero, then the
element's <dfn title="attr-textarea-cols-value">character
width</dfn> is that value; otherwise, it is 20.</span></p>
<div class="impl">
<p>The user agent may use the <code>textarea</code> element's <span
title="attr-textarea-cols-value">character width</span> as a hint to
the user as to how many characters the server prefers per line
(e.g. for visual user agents by making the width of the control be
that many characters). In visual renderings, the user agent should
wrap the user's input in the rendering so that each line is no wider
than this number of characters.</p>
</div>
<p>The <dfn title="attr-textarea-rows"><code>rows</code></dfn>
attribute specifies the number of lines to show. If the <code
title="attr-textarea-rows">rows</code> attribute is specified, its
value must be a <span>valid non-negative integer</span> greater than
zero. <span class="impl">If applying the <span>rules for parsing
non-negative integers</span> to the attribute's value results in a
number greater than zero, then the element's <dfn
title="attr-textarea-rows-value">character height</dfn> is that
value; otherwise, it is 2.</span></p>
<div class="impl">
<p>Visual user agents should set the height of the control to the
number of lines given by <span
title="attr-textarea-rows-value">character height</span>.</p>
</div>
<p>The <dfn title="attr-textarea-wrap"><code>wrap</code></dfn>
attribute is an <span>enumerated attribute</span> with two keywords
and states: the <dfn
title="attr-textarea-wrap-soft"><code>soft</code></dfn> keyword
which maps to the <dfn
title="attr-textarea-wrap-soft-state">Soft</dfn> state, and the
<dfn title="attr-textarea-wrap-hard"><code>hard</code></dfn> keyword
which maps to the <dfn
title="attr-textarea-wrap-hard-state">Hard</dfn> state. The
<i>missing value default</i> is the <span
title="attr-textarea-wrap-soft-state">Soft</span> state.</p>
<p>If the element's <code title="attr-textarea-wrap">wrap</code>
attribute is in the <span
title="attr-textarea-wrap-hard-state">Hard</span> state, the <code
title="attr-textarea-cols">cols</code> attribute must be
specified.</p>
<!-- attr-textarea-wrap-off (attr-textarea-wrap-off-state): not
conforming; turns off the rendering of wrapping but otherwise acts
like 'soft' -->
<div class="impl">
<p>The element's <span title="concept-fe-value">value</span> is
defined to be the element's <span
title="concept-textarea-raw-value">raw value</span> with the
following transformation applied:</p>
<ol>
<li><p>Replace every occurrence of a U+000D CARRIAGE RETURN (CR)
character not followed by a U+000A LINE FEED (LF) character, and
every occurrence of a U+000A LINE FEED (LF) character not preceded
by a U+000D CARRIAGE RETURN (CR) character, by a two-character
string consisting of a U+000D CARRIAGE RETURN - U+000A LINE FEED
(CRLF) character pair.</p></li>
<li><p>If the element's <code
title="attr-textarea-wrap">wrap</code> attribute is in the <span
title="attr-textarea-wrap-hard-state">Hard</span> state, insert
U+000D CARRIAGE RETURN - U+000A LINE FEED (CRLF) character pairs
into the string using a UA-defined algorithm so that each line has
no more than <span title="attr-textarea-cols-value">character
width</span> characters. For the purposes of this requirement,
lines are delimited by the start of the string, the end of the
string, and U+000D CARRIAGE RETURN - U+000A LINE FEED (CRLF)
character pairs.</p></li>
</ol>
</div>
<p>The <dfn
title="attr-textarea-maxlength"><code>maxlength</code></dfn>
attribute is a <span title="attr-fe-maxlength">form control <code
title="">maxlength</code> attribute</span> controlled by the
<code>textarea</code> element's <span
title="concept-textarea-dirty">dirty value flag</span>.</p>
<p>If the <code>textarea</code> element has a <span>maximum allowed
value length</span>, then the element's children must be such that
the <span>code-point length</span> of the value of the element's
<code>textContent</code> IDL attribute is equal to or less than the
element's <span>maximum allowed value length</span>.</p>
<p>The <dfn
title="attr-textarea-required"><code>required</code></dfn> attribute
is a <span>boolean attribute</span>. When specified, the user will
be required to enter a value before submitting the form.</p>
<div class="impl">
<p><strong>Constraint validation</strong>: If the element has its
<code title="attr-textarea-required">required</code> attribute
specified, and the element is <span
title="concept-textarea-mutable">mutable</span>, and the element's
<span title="concept-fe-value">value</span> is the empty string,
then the element is <span>suffering from being missing</span>.</p>
</div>
<!-- similar text in the <input> section -->
<p>The <dfn
title="attr-textarea-placeholder"><code>placeholder</code></dfn>
attribute represents a hint (a word or short phrase) intended to aid
the user with data entry. A hint could be a sample value or a brief
description of the expected format. The attribute, if specified,
must have a value that contains no U+000A LINE FEED (LF) or U+000D
CARRIAGE RETURN (CR) characters.</p>
<p class="note">For a longer hint or other advisory text, the <code
title="attr-title">title</code> attribute is more appropriate.</p>
<p>The <code title="attr-textarea-placeholder">placeholder</code>
attribute should not be used as an alternative to a
<code>label</code>.</p>
<div class="impl">
<p>User agents should present this hint to the user, after having
<span title="strip line breaks">stripped line breaks</span> from it,
when the element's <span title="concept-fe-value">value</span> is
the empty string and the control is not focused (e.g. by displaying
it inside a blank unfocused control).</p>
</div>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>textarea</code> element with its
<span>form owner</span>. The <code title="attr-fe-name">name</code>
attribute represents the element's name. The <code
title="attr-fe-disabled">disabled</code> attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The <code title="attr-fe-autofocus">autofocus</code>
attribute controls focus.</p>
<dl class="domintro">
<dt><var title="">textarea</var> . <code title="attr-textarea-type">type</code></dt>
<dd>
<p>Returns the string "<code title="">textarea</code>".</p>
</dd>
<dt><var title="">textarea</var> . <code title="attr-textarea-value">value</code></dt>
<dd>
<p>Returns the current value of the element.</p>
<p>Can be set, to change the value.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-textarea-cols"><code>cols</code></dfn>, <dfn
title="dom-textarea-placeholder"><code>placeholder</code></dfn>,
<dfn title="dom-textarea-required"><code>required</code></dfn>, <dfn
title="dom-textarea-rows"><code>rows</code></dfn>, and <dfn
title="dom-textarea-wrap"><code>wrap</code></dfn> attributes must
<span>reflect</span> the respective content attributes of the same
name. The <code title="dom-textarea-cols">cols</code> and <code
title="dom-textarea-rows">rows</code> attributes are <span>limited
to only non-negative numbers greater than zero</span>. The <dfn
title="dom-textarea-maxLength"><code>maxLength</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-textarea-maxlength">maxlength</code> content attribute,
<span>limited to only non-negative numbers</span>. The <dfn
title="dom-textarea-readOnly"><code>readOnly</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-textarea-readonly">readonly</code> content
attribute.</p>
<p>The <dfn title="dom-textarea-type"><code>type</code></dfn> IDL
attribute must return the value "<code title="">textarea</code>".</p>
<p>The <dfn
title="dom-textarea-defaultValue"><code>defaultValue</code></dfn>
IDL attribute must act like the element's <code>textContent</code>
IDL attribute.</p>
<p>The <dfn title="dom-textarea-value"><code>value</code></dfn>
attribute must, on getting, return the element's <span
title="concept-textarea-raw-value">raw value</span>; on setting, it
must set the element's <span title="concept-textarea-raw-value">raw
value</span> to the new value.</p>
<p>The <dfn
title="dom-textarea-textLength"><code>textLength</code></dfn> IDL
attribute must return the <span>code-point length</span> of the
element's <span title="concept-fe-value">value</span>.</p>
<p>The <code title="dom-cva-willValidate">willValidate</code>, <code
title="dom-cva-validity">validity</code>, and <code
title="dom-cva-validationMessage">validationMessage</code>
attributes, and the <code
title="dom-cva-checkValidatity">checkValidity()</code> and <code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
methods, are part of the <span>constraint validation API</span>. The
<code title="dom-lfe-labels">labels</code> attribute provides a list
of the element's <code>label</code>s. The <code
title="dom-textarea/input-select">select()</code>, <code
title="dom-textarea/input-selectionStart">selectionStart</code>,
<code title="dom-textarea/input-selectionEnd">selectionEnd</code>,
and <code
title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>
methods and attributes expose the element's text selection.</p>
</div>
<div class="example">
<p>Here is an example of a <code>textarea</code> being used for
unrestricted free-form text input in a form:</p>
<pre><p>If you have any comments, please let us know: <textarea cols=80 name=comments></textarea></p></pre>
</div>
<h4>The <dfn><code>keygen</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dd><span title="category-listed">Listed</span>, <span title="category-label">labelable</span>, <span title="category-submit">submittable</span>, and <span title="category-reset">resettable</span> <span>form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-fe-autofocus">autofocus</code></dd>
<dd><code title="attr-keygen-challenge">challenge</code></dd>
<dd><code title="attr-fe-disabled">disabled</code></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-keygen-keytype">keytype</code></dd>
<dd><code title="attr-fe-name">name</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLKeygenElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-fe-autofocus">autofocus</span>;
attribute DOMString <span title="dom-keygen-challenge">challenge</span>;
attribute boolean <span title="dom-fe-disabled">disabled</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
attribute DOMString <span title="dom-keygen-keytype">keytype</span>;
attribute DOMString <span title="dom-fe-name">name</span>;
readonly attribute DOMString <span title="dom-keygen-type">type</span>;
readonly attribute boolean <span title="dom-cva-willValidate">willValidate</span>;
readonly attribute <span>ValidityState</span> <span title="dom-cva-validity">validity</span>;
readonly attribute DOMString <span title="dom-cva-validationMessage">validationMessage</span>;
boolean <span title="dom-cva-checkValidatity">checkValidity</span>();
void <span title="dom-cva-setCustomValidity">setCustomValidity</span>(in DOMString error);
readonly attribute <span>NodeList</span> <span title="dom-lfe-labels">labels</span>;
};</pre>
</dd>
</dl>
<p>The <code>keygen</code> element <span>represents</span> a key
pair generator control. When the control's form is submitted, the
private key is stored in the local keystore, and the public key is
packaged and sent to the server.</p>
<p>The <dfn
title="attr-keygen-challenge"><code>challenge</code></dfn> attribute
may be specified. Its value will be packaged with the submitted
key.</p>
<p>The <dfn title="attr-keygen-keytype"><code>keytype</code></dfn>
attribute is an <span>enumerated attribute</span>. The following
table lists the keywords and states for the attribute — the
keywords in the left column map to the states listed in the cell in
the second column on the same row as the keyword. User agents are
not required to support these values, and must only recognise values
whose corresponding algorithms they support.</p>
<table>
<thead> <tr> <th> Keyword <th> State
<tbody>
<tr>
<td> <code title="">rsa</code>
<td> <i title="">RSA</i>
<!-- v2 (see below)
<tr>
<td> <code title="">ec</code>
<td> <i title="">EC</i>
-->
</table>
<p>The <i>invalid value default</i> state is the <i
title="">unknown</i> state. The <i>missing value default</i> state
is the <i title="">RSA</i> state, if it is supported, or the <i
title="">unknown</i> state otherwise.</p>
<p class="note">This specification does not specify what key types
user agents are to support — it is possible for a user agent
to not support any key types at all.</p>
<div class="impl">
<p>The user agent may expose a user interface for each
<code>keygen</code> element to allow the user to configure settings
of the element's key pair generator, e.g. the key length.</p>
<p>The <span title="concept-form-reset-control">reset
algorithm</span> for <code>keygen</code> elements is to set these
various configuration settings back to their defaults.</p>
<p>The element's <span title="concept-fe-value">value</span> is the
string returned from the following algorithm:</p>
<ol>
<li>
<p>Use the appropriate step from the following list:</p>
<dl class="switch">
<!-- v2 (see above)
<dt>If the <code title="attr-keygen-keytype">keytype</code>
attribute is in the <i title="">EC</i> state</dt>
<dd>
<p>...
http://www.mail-archive.com/dev-tech-crypto@lists.mozilla.org/msg05902.html
</dd>
-->
<dt>If the <code title="attr-keygen-keytype">keytype</code>
attribute is in the <i title="">RSA</i> state</dt>
<dd>
<p>Generate an RSA key pair using the settings given by the
user, if appropriate, using the <code
title="">md5WithRSAEncryption</code> RSA signature algorithm
(the signature algorithm with MD5 and the RSA encryption
algorithm) referenced in section 2.2.1 ("RSA Signature
Algorithm") of RFC 3279, and defined in RFC 2313. <a
href="#refsRFC3279">[RFC3279]</a> <a
href="#refsRFC2313">[RFC2313]</a></p>
</dd>
<dt>Otherwise, the <code
title="attr-keygen-keytype">keytype</code> attribute is in the <i
title="">unknown</i> state</dt>
<dd>
<p>The given key type is not supported. Return the empty string
and abort this algorithm.</p>
</dd>
</dl>
<p>Let <var title="">private key</var> be the generated private key.</p>
<p>Let <var title="">public key</var> be the generated public key.</p>
<p>Let <var title="">signature algorithm</var> be the selected
signature algorithm.</p>
</li>
<li>
<p>If the element has a <code
title="attr-keygen-challenge">challenge</code> attribute, then let
<var title="">challenge</var> be that attribute's value.
Otherwise, let <var title="">challenge</var> be the empty
string.</p>
</li>
<li>
<p>Let <var title="">algorithm</var> be an ASN.1 <code
title="">AlgorithmIdentifier</code> structure as defined by
RFC 5280, with the <code title="">algorithm</code> field giving the
ASN.1 OID used to identify <var title="">signature
algorithm</var>, using the OIDs defined in section 2.2 ("Signature
Algorithms") of RFC 3279, and the <code title="">parameters</code>
field set up as required by RFC 3279 for <code
title="">AlgorithmIdentifier</code> structures for that
algorithm. <a href="#refsX690">[X690]</a> <a
href="#refsRFC5280">[RFC5280]</a> <a
href="#refsRFC3279">[RFC3279]</a></p>
</li>
<li>
<p>Let <var title="">spki</var> be an ASN.1 <code
title="">SubjectPublicKeyInfo</code> structure as defined by
RFC 5280, with the <code title="">algorithm</code> field set to the
<var title="">algorithm</var> structure from the previous step,
and the <code title="">subjectPublicKey</code> field set to the
BIT STRING value resulting from ASN.1 DER encoding the <var
title="">public key</var>. <a href="#refsX690">[X690]</a> <a
href="#refsRFC5280">[RFC5280]</a></p>
</li>
<li>
<p>Let <var title="">publicKeyAndChallenge</var> be an ASN.1
<code>PublicKeyAndChallenge</code> structure as defined below,
with the <code title="">spki</code> field set to the <var
title="">spki</var> structure from the previous step, and the
<code title="">challenge</code> field set to the string <var
title="">challenge</var> obtained earlier. <a
href="#refsX690">[X690]</a></p>
</li>
<li>
<p>Let <var title="">signature</var> be the BIT STRING value
resulting from ASN.1 DER encoding the signature generated by
applying the <var title="">signature algorithm</var> to the byte
string obtained by ASN.1 DER encoding the <var
title="">publicKeyAndChallenge</var> structure, using <var
title="">private key</var> as the signing key. <a
href="#refsX690">[X690]</a></p>
</li>
<li>
<p>Let <var title="">signedPublicKeyAndChallenge</var> be an ASN.1
<code>SignedPublicKeyAndChallenge</code> structure as defined
below, with the <code title="">publicKeyAndChallenge</code> field
set to the <var title="">publicKeyAndChallenge</var> structure,
the <code title="">signatureAlgorithm</code> field set to the <var
title="">algorithm</var> structure, and the <code
title="">signature</code> field set to the BIT STRING <var
title="">signature</var> from the previous step. <a
href="#refsX690">[X690]</a></p>
</li>
<li>
<p>Return the result of base64 encoding the result of ASN.1 DER
encoding the <var title="">signedPublicKeyAndChallenge</var>
structure. <a href="#refsRFC3548">[RFC3548]</a><!--base64--> <a
href="#refsX690">[X690]</a></p>
</li>
</ol>
<p>The data objects used by the above algorithm are defined as
follows. These definitions use the same "ASN.1-like" syntax defined
by RFC 5280. <a href="#refsRFC5280">[RFC5280]</a></p>
<pre class="asn"><dfn>PublicKeyAndChallenge</dfn> ::= SEQUENCE {
spki <span>SubjectPublicKeyInfo</span>,
challenge IA5STRING
}
<dfn>SignedPublicKeyAndChallenge</dfn> ::= SEQUENCE {
publicKeyAndChallenge <span>PublicKeyAndChallenge</span>,
signatureAlgorithm <span>AlgorithmIdentifier</span>,
signature BIT STRING
}</pre>
<hr>
<p><strong>Constraint validation</strong>: The <code>keygen</code>
element is <span>barred from constraint validation</span>.</p>
</div>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>keygen</code> element with its
<span>form owner</span>. The <code title="attr-fe-name">name</code>
attribute represents the element's name. The <code
title="attr-fe-disabled">disabled</code> attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The <code title="attr-fe-autofocus">autofocus</code>
attribute controls focus.</p>
<dl class="domintro">
<dt><var title="">keygen</var> . <code title="attr-keygen-type">type</code></dt>
<dd>
<p>Returns the string "<code title="">keygen</code>".</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-keygen-challenge"><code>challenge</code></dfn> IDL
attribute must <span>reflect</span> the content attributes of the
same name.</p>
<p>The <dfn title="dom-keygen-keytype"><code>keytype</code></dfn>
IDL attribute must <span>reflect</span> the content attributes of
the same name, <span>limited to only known values</span>.</p>
<p>The <dfn title="dom-keygen-type"><code>type</code></dfn> IDL
attribute must return the value "<code title="">keygen</code>".</p>
<p>The <code title="dom-cva-willValidate">willValidate</code>, <code
title="dom-cva-validity">validity</code>, and <code
title="dom-cva-validationMessage">validationMessage</code>
attributes, and the <code
title="dom-cva-checkValidatity">checkValidity()</code> and <code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
methods, are part of the <span>constraint validation API</span>. The
<code title="dom-lfe-labels">labels</code> attribute provides a list
of the element's <code>label</code>s.</p>
</div>
<p class="note">This specification does not specify how the private
key generated is to be used. It is expected that after receiving the
<code>SignedPublicKeyAndChallenge</code> (SPKAC) structure, the
server will generate a client certificate and offer it back to the
user for download; this certificate, once downloaded and stored in
the key store along with the private key, can then be used to
authenticate to services that use SSL and certificate
authentication.</p>
<!-- how does the UA know which private key is associated with a
certificate it gets back after the server has taken the public key
created by <keygen> and turned it into a client cert? -->
<div class="example">
<p>To generate a key pair, add the private key to the user's key
store, and submit the public key to the server, markup such as the
following can be used:</p>
<pre><form action="processkey.cgi" method="post" enctype="multipart/formdata">
<p><keygen name="key"></p>
<p><input type=submit value="Submit key..."></p>
</form></pre>
<p>The server will then receive a form submission with a packaged
RSA public key as the value of "<code title="">key</code>". This
can then be used for various purposes, such as generating a client
certificate, as mentioned above.</p>
</div>
<h4>The <dfn><code>output</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dd><span title="category-listed">Listed</span> and <span title="category-reset">resettable</span> <span>form-associated element</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Phrasing content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-output-for">for</code></dd>
<dd><code title="attr-fae-form">form</code></dd>
<dd><code title="attr-fe-name">name</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLOutputElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-output-wrap">htmlFor</span>;
readonly attribute <span>HTMLFormElement</span> <span title="dom-fae-form">form</span>;
attribute DOMString <span title="dom-fe-name">name</span>;
readonly attribute DOMString <span title="dom-output-type">type</span>;
attribute DOMString <span title="dom-output-defaultValue">defaultValue</span>;
attribute DOMString <span title="dom-output-value">value</span>;
readonly attribute boolean <span title="dom-cva-willValidate">willValidate</span>;
readonly attribute <span>ValidityState</span> <span title="dom-cva-validity">validity</span>;
readonly attribute DOMString <span title="dom-cva-validationMessage">validationMessage</span>;
boolean <span title="dom-cva-checkValidatity">checkValidity</span>();
void <span title="dom-cva-setCustomValidity">setCustomValidity</span>(in DOMString error);
};</pre>
</dd>
</dl>
<p>The <code>output</code> element <span>represents</span> the result of a
calculation.</p>
<p>The <dfn title="attr-output-for"><code>for</code></dfn> content
attribute allows an explicit relationship to be made between the
result of a calculation and the elements that represent the values
that went into the calculation or that otherwise influenced the
calculation. The <code title="attr-output-for">for</code> attribute,
if specified, must contain a string consisting of an <span>unordered
set of unique space-separated tokens</span>, each of which must have
the value of an ID of an element in the same
<code>Document</code>.</p>
<p>The <code title="attr-fae-form">form</code> attribute is used to
explicitly associate the <code>output</code> element with its
<span>form owner</span>. The <code title="attr-fe-name">name</code>
attribute represents the element's name.</p>
<div class="impl">
<p>The element has a <dfn title="concept-output-mode">value mode
flag</dfn> which is either <i
title="concept-output-mode-value">value</i> or <i
title="concept-output-mode-default">default</i>. Initially, the
<span title="concept-output-mode">value mode flag</span> must be set
to <i title="concept-output-mode-default">default</i>.</p>
<p>When the <span title="concept-output-mode">value mode
flag</span> is in mode <i
title="concept-output-mode-default">default</i>, the contents of the
element represent both the value of the element and its default
value. When the <span title="concept-output-mode">value mode
flag</span> is in mode <i
title="concept-output-mode-value">value</i>, the contents of the
element represent the value of the element only, and the default
value is only accessible using the <code
title="dom-output-defaultValue">defaultValue</code> IDL
attribute.</p>
<p>The element also has a <dfn
title="concept-output-defaultValue">default value</dfn>. Initially,
the <span title="concept-output-defaultValue">default value</span>
must be the empty string.</p>
<p>Whenever the element's descendants are changed in any way, if the
<span title="concept-output-mode">value mode flag</span> is in mode
<i title="concept-output-mode-default">default</i>, the element's
<span title="concept-output-defaultValue">default value</span> must
be set to the value of the element's <code>textContent</code> IDL
attribute.</p>
<p>The <span title="concept-form-reset-control">reset
algorithm</span> for <code>output</code> elements is to set the
element's <code>textContent</code> IDL attribute to the value of the
element's <code title="dom-output-defaultValue">defaultValue</code>
IDL attribute (thus replacing the element's child nodes), and then
to set the element's <span title="concept-output-mode">value mode
flag</span> to <i
title="concept-output-mode-default">default</i>.</p>
</div>
<dl class="domintro">
<dt><var title="">output</var> . <code title="dom-output-value">value</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the element's current value.</p>
<p>Can be set, to change the value.</p>
</dd>
<dt><var title="">output</var> . <code title="dom-output-defaultValue">defaultValue</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the element's current default value.</p>
<p>Can be set, to change the default value.</p>
</dd>
<dt><var title="">output</var> . <code title="dom-output-type">type</code></dt>
<dd>
<p>Returns the string "<code title="">output</code>".</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-output-value"><code>value</code></dfn> IDL
attribute must act like the element's <code>textContent</code> IDL
attribute, except that on setting, in addition, before the child
nodes are changed, the element's <span
title="concept-output-mode">value mode flag</span> must be set to <i
title="concept-output-mode-value">value</i>.</p>
<p>The <dfn
title="dom-output-defaultValue"><code>defaultValue</code></dfn> IDL
attribute, on getting, must return the element's <span
title="concept-output-defaultValue">default value</span>. On
setting, the attribute must set the element's <span
title="concept-output-defaultValue">default value</span>, and, if
the element's <span title="concept-output-mode">value mode
flag</span> is in the mode <i
title="concept-output-mode-default">default</i>, set the element's
<code>textContent</code> IDL attribute as well.</p>
<p>The <dfn title="dom-output-type"><code>type</code></dfn>
attribute must return the string "<code title="">output</code>".</p>
<p>The <dfn title="dom-output-htmlFor"><code>htmlFor</code></dfn>
IDL attribute must <span>reflect</span> the <code
title="attr-output-for">for</code> content attribute.</p>
<p>The <code title="dom-cva-willValidate">willValidate</code>,
<code title="dom-cva-validity">validity</code>, and <code
title="dom-cva-validationMessage">validationMessage</code>
attributes, and the <code
title="dom-cva-checkValidatity">checkValidity()</code> and
<code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
methods, are part of the <span>constraint validation API</span>.</p>
<p><strong>Constraint validation</strong>: <code>output</code>
elements are always <span>barred from constraint
validation</span>.</p>
</div>
<div class="example">
<p>A simple calculator could use <code>output</code> for its
display of calculated results:</p>
<pre><form onsubmit="return false">
<input name=a type=number step=any> +
<input name=b type=number step=any> =
<output onforminput="value = a.value + b.value"></output>
</form></pre>
</div>
<h4>Association of controls and forms</h4>
<p>A <span>form-associated element</span> can have a relationship
with a <code>form</code> element, which is called the element's
<dfn>form owner</dfn>. If a <span>form-associated element</span> is
not associated with a <code>form</code> element, its <span>form
owner</span> is said to be null.</p>
<p>A <span>form-associated element</span> is, by default, associated
with its nearest ancestor <code>form</code> element<span
class="impl"> (as described below)</span>, but may have a <dfn
title="attr-fae-form"><code>form</code></dfn> attribute specified to
override this.</p>
<p>If a <span>form-associated element</span> has a <code
title="attr-fae-form">form</code> attribute specified, then its
value must be the ID of a <code>form</code> element in the element's
owner <code>Document</code>.</p>
<div class="impl">
<p>When a <span>form-associated element</span> is created, its
<span>form owner</span> must be initialized to null (no owner).</p>
<p>When a <span>form-associated element</span> is to be <dfn
title="concept-form-association">associated</dfn> with a form, its
<span>form owner</span> must be set to that form.</p>
<p>When a <span>form-associated element</span>'s ancestor chain
changes, e.g. because it or one of its ancestors was <span
title="insert an element into a document">inserted</span> or <span
title="remove an element from a document">removed</span> from a
<code>Document</code>, then the user agent must <span>reset the form
owner</span> of that element.</p>
<p>When a <span>form-associated element</span>'s <code
title="attr-fae-form">form</code> attribute is added, removed, or
has its value changed, then the user agent must <span>reset the form
owner</span> of that element.</p>
<p>When a <span>form-associated element</span> has a <code
title="attr-fae-form">form</code> attribute and the ID of any of the
<code>form</code> elements in the <code>Document</code> changes,
then the user agent must <span>reset the form owner</span> of that
<span>form-associated element</span>.</p>
<p>When the user agent is to <dfn>reset the form owner</dfn> of a
<span>form-associated element</span>, it must run the following
steps:</p>
<ol>
<li><p>If the element's <span>form owner</span> is not null, and
the element's <code title="attr-fae-form">form</code> content
attribute is not present, and the element's <span>form owner</span>
is one of the ancestors of the element after the change to the
ancestor chain, then do nothing, and abort these steps.</p></li>
<li><p>Let the element's <span>form owner</span> be null.</p></li>
<li>
<p>If the element has a <code title="attr-fae-form">form</code>
content attribute, then run these substeps:</p>
<ol>
<!-- note that this ignores the name="" attribute and is
unaffected by quirks mode (it's always case sensitive) -->
<li><p>If the first element in the <code>Document</code> to have
an ID that is <span
title="case-sensitive">case-sensitively</span> equal to the
element's <code title="attr-fae-form">form</code> content
attribute's value is a <code>form</code> element, then <span
title="concept-form-association">associate</span> the
<span>form-associated element</span> with that <code>form</code>
element.</p></li>
<li><p>Abort the "reset the form owner" steps.</p></li>
</ol>
</li>
<li><p>Otherwise, if the <span>form-associated element</span> in
question has an ancestor <code>form</code> element, then <span
title="concept-form-association">associate</span> the
<span>form-associated element</span> with the nearest such ancestor
<code>form</code> element.</p></li>
<li><p>Otherwise, the element is left unassociated.</p></li>
</ol>
<div class="example">
<p>In the following non-conforming snippet:</p>
<pre class="bad">...
<form id="a">
<div id="b"></div>
</form>
<script>
document.getElementById('b').innerHTML =
'<table><tr><td><form id="c"><input id="d"></table>' +
'<input id="e">';
</script>
...</pre>
<p>The <span>form owner</span> of "d" would be the inner nested
form "c", while the <span>form owner</span> of "e" would be the
outer form "a".</p>
<p>This is because despite the association of "e" with "c" in the
<span>HTML parser</span>, when the <code
title="dom-innerHTML">innerHTML</code> algorithm moves the nodes
from the temporary document to the "b" element, the nodes see their
ancestor chain change, and thus all the "magic" associations done
by the parser are reset to normal ancestor associations.</p>
<p>This example is a non-conforming document, though, as it is a
violation of the content models to nest <code>form</code>
elements.</p>
</div>
</div>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-fae-form">form</code></dt>
<dd>
<p>Returns the element's <span>form owner</span>.</p>
<p>Returns null if there isn't one.</p>
</dd>
</dl>
<div class="impl">
<p><span title="form-associated element">Form-associated
elements</span> have a <dfn
title="dom-fae-form"><code>form</code></dfn> IDL attribute, which,
on getting, must return the element's <span>form owner</span>, or
null if there isn't one.</p>
<p><strong>Constraint validation</strong>: If an element has no
<span>form owner</span>, it is <span>barred from constraint
validation</span>.</p>
</div>
<h4><dfn>Attributes common to form controls</dfn></h4>
<h5>Naming form controls</h5>
<p>The <dfn title="attr-fe-name"><code>name</code></dfn> content
attribute gives the name of the form control, as used in <span>form
submission</span> and in the <code>form</code> element's <code
title="dom-form-elements">elements</code> object. If the attribute
is specified, its value must not be the empty string.</p>
<div class="impl">
<p><strong>Constraint validation</strong>: If an element does not
have a <code title="attr-fe-name">name</code> attribute specified,
or its <code title="attr-fe-name">name</code> attribute's value is
the empty string, then it is <span>barred from constraint
validation</span>.</p>
<p>The <dfn title="dom-fe-name"><code>name</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-fe-name">name</code> content attribute.</p>
</div>
<h5>Enabling and disabling form controls</h5>
<p>The <dfn title="attr-fe-disabled"><code>disabled</code></dfn>
content attribute is a <span>boolean attribute</span>.</p>
<p>A form control is <dfn title="concept-fe-disabled">disabled</dfn>
if its <code title="attr-fe-disabled">disabled</code> attribute is
set, or if it is a descendant of a <code>fieldset</code> element
whose <code title="attr-fieldset-disabled">disabled</code> attribute
is set and is <em>not</em> a descendant of that
<code>fieldset</code> element's first <code>legend</code> element
child, if any.</p>
<div class="impl">
<p>A form control that is <span
title="concept-fe-disabled">disabled</span> must prevent any <code
title="event-click">click</code> events that are <span title="queue
a task">queued</span> on the <span>user interaction task
source</span> from being dispatched on the element.</p>
<p><strong>Constraint validation</strong>: If an element is <span
title="concept-fe-disabled">disabled</span>, it is <span>barred from
constraint validation</span>.</p>
<p>The <dfn title="dom-fe-disabled"><code>disabled</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-fe-disabled">disabled</code> content attribute.</p>
</div>
<div class="impl">
<h5>A form control's value</h5>
<p>Form controls have a <dfn title="concept-fe-value">value</dfn>
and a <dfn title="concept-fe-checked">checkedness</dfn>. (The latter
is only used by <code>input</code> elements.) These are used to
describe how the user interacts with the control.</p>
</div>
<h5>Autofocusing a form control</h5>
<!-- v2: Apply this to contentEditable elements -->
<p>The <dfn title="attr-fe-autofocus"><code>autofocus</code></dfn>
content attribute allows the user to indicate that a control is to
be focused as soon as the page is loaded, allowing the user to just
start typing without having to manually focus the main control.</p>
<p>The <code title="attr-fe-autofocus">autofocus</code> attribute is
a <span>boolean attribute</span>.</p>
<p>There must not be more than one element in the document with the
<code title="attr-fe-autofocus">autofocus</code> attribute
specified.</p>
<div class="impl">
<p>Whenever an element with the <code
title="attr-fe-autofocus">autofocus</code> attribute specified is
<span title="insert an element into a document">inserted into a
document</span>, the user agent should <span>queue a task</span>
that checks to see if the element is <span>focusable</span>, and if
so, runs the <span>focusing steps</span> for that element. User
agents may also change the scrolling position of the document, or
perform some other action that brings the element to the user's
attention. The <span>task source</span> for this task is the
<span>DOM manipulation task source</span>.</p>
<p>User agents may ignore this attribute if the user has indicated
(for example, by starting to type in a form control) that he does
not wish focus to be changed.</p>
<p class="note">Focusing the control does not imply that the user
agent must focus the browser window if it has lost focus.</p>
<p>The <dfn title="dom-fe-autofocus"><code>autofocus</code></dfn>
IDL attribute must <span>reflect</span> the content attribute of the
same name.</p>
</div>
<div class="example">
<p>In the following snippet, the text control would be focused when
the document was loaded.</p>
<pre><input maxlength="256" name="q" value="" autofocus>
<input type="submit" value="Search"></pre>
</div>
<h5>Limiting user input length</h5>
<p>A <dfn title="attr-fe-maxlength">form control <code
title="">maxlength</code> attribute</dfn>, controlled by a <var
title="">dirty value flag</var> declares a limit on the number of
characters a user can input.</p>
<p>If an element has its <span title="attr-fe-maxlength">form
control <code title="">maxlength</code> attribute</span> specified,
the attribute's value must be a <span>valid non-negative
integer</span>. If the attribute is specified and applying the
<span>rules for parsing non-negative integers</span> to its value
results in a number, then that number is the element's <dfn>maximum
allowed value length</dfn>. If the attribute is omitted or parsing
its value results in an error, then there is no <span>maximum
allowed value length</span>.</p>
<div class="impl">
<p><strong>Constraint validation</strong>: If an element has a
<span>maximum allowed value length</span>, and its <var
title="">dirty value flag</var> is true, and the <span>code-point
length</span> of the element's <span
title="concept-fe-value">value</span> is greater than the element's
<span>maximum allowed value length</span>, then the element is
<span>suffering from being too long</span>.</p>
<p>User agents may prevent the user from causing the element's <span
title="concept-fe-value">value</span> to be set to a value whose
<span>code-point length</span> is greater than the element's
<span>maximum allowed value length</span>.</p>
</div>
<h5>Form submission</h5>
<p><dfn>Attributes for form submission</dfn> can be specified both
on <code>form</code> elements and on <span
title="concept-submit-button">submit buttons</span> (elements that
represent buttons that submit forms, e.g. an <code>input</code>
element whose <code title="attr-input-type">type</code> attribute is
in the <span title="attr-input-type-submit">Submit Button</span>
state).
<p>The <span>attributes for form submission</span> that may be
specified on <code>form</code> elements are <code
title="attr-fs-action">action</code>, <code
title="attr-fs-enctype">enctype</code>, <code
title="attr-fs-method">method</code>, <code
title="attr-fs-novalidate">novalidate</code>, and <code
title="attr-fs-target">target</code>.</p>
<p>The corresponding <span>attributes for form submission</span>
that may be specified on <span title="concept-submit-button">submit
buttons</span> are <code
title="attr-fs-formaction">formaction</code>, <code
title="attr-fs-formenctype">formenctype</code>, <code
title="attr-fs-formmethod">formmethod</code>, <code
title="attr-fs-formnovalidate">formnovalidate</code>, and <code
title="attr-fs-formtarget">formtarget</code>. When omitted, they
default to the values given on the corresponding attributes on the
<code>form</code> element.</p>
<hr>
<p>The <dfn title="attr-fs-action"><code>action</code></dfn> and
<dfn title="attr-fs-formaction"><code>formaction</code></dfn>
content attributes, if specified, must have a value that is a
<span>valid URL</span>.</p>
<p>The <dfn title="concept-fs-action">action</dfn> of an element is
the value of the element's <code
title="attr-fs-formaction">formaction</code> attribute, if the
element is a <span title="concept-submit-button">submit
button</span> and has such an attribute, or the value of its
<span>form owner</span>'s <code title="attr-fs-action">action</code>
attribute, if <em>it</em> has one, or else the empty string.</p>
<hr>
<p>The <dfn title="attr-fs-method"><code>method</code></dfn> and
<dfn title="attr-fs-formmethod"><code>formmethod</code></dfn>
content attributes are <span title="enumerated attribute">enumerated
attributes</span> with the following keywords and states:</p>
<ul>
<li>The keyword <dfn
title="attr-fs-method-GET-keyword"><code>GET</code></dfn>, mapping
to the state <dfn title="attr-fs-method-GET">GET</dfn>, indicating
the HTTP GET method.</li>
<li>The keyword <dfn
title="attr-fs-method-POST-keyword"><code>POST</code></dfn>, mapping
to the state <dfn title="attr-fs-method-POST">POST</dfn>, indicating
the HTTP POST method.</li>
<li>The keyword <dfn
title="attr-fs-method-PUT-keyword"><code>PUT</code></dfn>, mapping
to the state <dfn title="attr-fs-method-PUT">PUT</dfn>, indicating
the HTTP PUT method.</li>
<li>The keyword <dfn
title="attr-fs-method-DELETE-keyword"><code>DELETE</code></dfn>, mapping
to the state <dfn title="attr-fs-method-DELETE">DELETE</dfn>, indicating
the HTTP DELETE method.</li>
</ul>
<p>The <i>missing value default</i> for these attributes is the
<span title="attr-fs-method-GET">GET</span> state.</p>
<p>The <dfn title="concept-fs-method">method</dfn> of an element is
one of those four states. If the element is a <span
title="concept-submit-button">submit button</span> and has a <code
title="attr-fs-formmethod">formmethod</code> attribute, then the
element's <span title="concept-fs-method">method</span> is that
attribute's state; otherwise, it is the <span>form owner</span>'s
<code title="attr-fs-method">method</code> attribute's state.</p>
<hr>
<p>The <dfn title="attr-fs-enctype"><code>enctype</code></dfn> and
<dfn title="attr-fs-formenctype"><code>formenctype</code></dfn>
content attributes are <span title="enumerated attribute">enumerated
attributes</span> with the following keywords and states:</p>
<ul>
<li>The "<dfn title="attr-fs-enctype-urlencoded"><code>application/x-www-form-urlencoded</code></dfn>" keyword and corresponding state.</li>
<li>The "<dfn title="attr-fs-enctype-formdata"><code>multipart/form-data</code></dfn>" keyword and corresponding state.</li>
<li>The "<dfn title="attr-fs-enctype-text"><code>text/plain</code></dfn>" keyword and corresponding state.</li>
</ul>
<p>The <i>missing value default</i> for these attributes is the
<code
title="attr-fs-enctype-urlencoded">application/x-www-form-urlencoded</code>
state.</p>
<p>The <dfn title="concept-fs-enctype">enctype</dfn> of an element
is one of those three states. If the element is a <span
title="concept-submit-button">submit button</span> and has a <code
title="attr-fs-formenctype">formenctype</code> attribute, then the
element's <span title="concept-fs-enctype">enctype</span> is that
attribute's state; otherwise, it is the <span>form owner</span>'s
<code title="attr-fs-enctype">enctype</code> attribute's state.</p>
<hr>
<p>The <dfn title="attr-fs-target"><code>target</code></dfn> and
<dfn title="attr-fs-formtarget"><code>formtarget</code></dfn>
content attributes, if specified, must have values that are <span
title="valid browsing context name or keyword">valid browsing
context names or keywords</span>.</p>
<p>The <dfn title="concept-fs-target">target</dfn> of an element is
the value of the element's <code
title="attr-fs-formtarget">formtarget</code> attribute, if the
element is a <span title="concept-submit-button">submit
button</span> and has such an attribute; or the value of its
<span>form owner</span>'s <code title="attr-fs-target">target</code>
attribute, if <em>it</em> has such an attribute; or, if one of the
child nodes of <span>the <code>head</code> element</span> is a
<code>base</code> element with a <code
title="attr-base-target">target</code> attribute, then the value of
the <code title="attr-base-target">target</code> attribute of the
first such <code>base</code> element; or, if there is no such
element, the empty string.</p> <!-- c.f. hyperlink following -->
<hr>
<p>The <dfn title="attr-fs-novalidate"><code>novalidate</code></dfn>
and <dfn
title="attr-fs-formnovalidate"><code>formnovalidate</code></dfn>
content attributes are <span title="boolean attribute">boolean
attributes</span>. If present, they indicate that the form is not to
be validated during submission.</p>
<p>The <dfn title="concept-fs-novalidate">no-validate state</dfn> of
an element is true if the element is a <span
title="concept-submit-button">submit button</span> and the element's
<code title="attr-fs-formnovalidate">formnovalidate</code> attribute
is present, or if the element's <span>form owner</span>'s <code
title="attr-fs-novalidate">novalidate</code> attribute is present,
and false otherwise.</p>
<div class="example">
<p>This attribute is useful to include "save" buttons on forms that
have validation constraints, to allow users to save their progress
even though they haven't fully entered the data in the form. The
following example shows a simple form that has two required
fields. There are three buttons: one to submit the form, which
requires both fields to be filled in; one to save the form so that
the user can come back and fill it in later; and one to cancel the
form altogether.</p>
<pre><form action="editor.cgi" method="post">
<p><label>Name: <input required name=fn></label></p>
<p><label>Essay: <textarea name=essay></textarea></label></p>
<p><input type=submit name=submit value="Submit essay"></p>
<p><input type=submit formnovalidate name=save value="Save essay"></p>
<p><input type=submit formnovalidate name=cancel value="Cancel"></p>
</form></pre>
</div>
<div class="impl">
<hr>
<p>The <dfn title="dom-fs-action"><code>action</code></dfn>, <dfn
title="dom-fs-method"><code>method</code></dfn>, <dfn
title="dom-fs-enctype"><code>enctype</code></dfn>, and <dfn
title="dom-fs-target"><code>target</code></dfn> IDL attributes must
<span>reflect</span> the respective content attributes of the same
name. The <dfn
title="dom-fs-noValidate"><code>noValidate</code></dfn> IDL
attribute must reflect the <code
title="attr-fs-novalidate">novalidate</code> content attribute. The
<dfn title="dom-fs-formAction"><code>formAction</code></dfn> IDL
attribute must reflect the <code
title="attr-fs-formaction">formaction</code> content attribute. The
<dfn title="dom-fs-formEnctype"><code>formEnctype</code></dfn> IDL
attribute must reflect the <code
title="attr-fs-formenctype">formenctype</code> content attribute.
The <dfn title="dom-fs-formMethod"><code>formMethod</code></dfn> IDL
attribute must reflect the <code
title="attr-fs-formmethod">formmethod</code> content attribute. The
<dfn title="dom-fs-formNoValidate"><code>formNoValidate</code></dfn>
IDL attribute must reflect the <code
title="attr-fs-formnovalidate">formnovalidate</code> content
attribute. The <dfn
title="dom-fs-formTarget"><code>formTarget</code></dfn> IDL
attribute must reflect the <code
title="attr-fs-formtarget">formtarget</code> content attribute.
</div>
<h4>Constraints</h4>
<h5>Definitions</h5>
<div class="impl">
<p>A <span title="category-listed">listed form-associated
element</span> is a <dfn>candidate for constraint validation</dfn>
except when a condition has <dfn title="barred from constraint
validation">barred the element from constraint
validation</dfn>. (For example, an element is <span>barred from
constraint validation</span> if it is an <code>output</code> or
<code>fieldset</code> element.)</p>
<p>An element can have a <dfn>custom validity error message</dfn>
defined. Initially, an element must have its <span>custom validity
error message</span> set to the empty string. When its value is not
the empty string, the element is <span>suffering from a custom
error</span>. It can be set using the <code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
method. The user agent should use the <span>custom validity error
message</span> when alerting the user to the problem with the
control.</p>
<p>An element can be constrained in various ways. The following is
the list of <dfn>validity states</dfn> that a form control can be
in, making the control invalid for the purposes of constraint
validation. (The definitions below are non-normative; other parts of
this specification define more precisely when each state applies or
does not.)</p>
<dl>
<dt> <dfn>Suffering from being missing</dfn> </dt>
<dd> <p>When a control has no <span
title="concept-fe-value">value</span> but has a <code
title="">required</code> attribute (<code>input</code> <code
title="attr-input-required">required</code>, <code>textarea</code>
<code title="attr-textarea-required">required</code>). </p></dd>
<dt> <dfn>Suffering from a type mismatch</dfn> </dt>
<dd> <p>When a control that allows arbitrary user
input has a <span title="concept-fe-value">value</span> that is not
in the correct syntax (<span
title="attr-input-type-email">E-mail</span>, <span
title="attr-input-type-url">URL</span>). </p></dd>
<dt> <dfn>Suffering from a pattern mismatch</dfn> </dt>
<dd> <p>When a control has a <span
title="concept-fe-value">value</span> that doesn't satisfy the
<code title="attr-input-pattern">pattern</code> attribute.</p></dd>
<dt> <dfn>Suffering from being too long</dfn> </dt>
<dd> <p>When a control has a <span
title="concept-fe-value">value</span> that is too long for the
<span title="attr-fe-maxlength">form control <code
title="">maxlength</code> attribute</span> (<code>input</code>
<code title="attr-input-maxlength">maxlength</code>,
<code>textarea</code> <code
title="attr-textarea-maxlength">maxlength</code>). </p></dd>
<dt> <dfn>Suffering from an underflow</dfn> </dt>
<dd> <p>When a control has a <span
title="concept-fe-value">value</span> that is too low for the <code
title="attr-input-min">min</code> attribute.</p></dd>
<dt> <dfn>Suffering from an overflow</dfn> </dt>
<dd> <p>When a control has a <span
title="concept-fe-value">value</span> that is too high for the
<code title="attr-input-max">max</code> attribute.</p></dd>
<dt> <dfn>Suffering from a step mismatch</dfn> </dt>
<dd> <p>When a control has a <span
title="concept-fe-value">value</span> that doesn't fit the rules
given by the <code title="attr-input-step">step</code>
attribute.</p></dd>
<dt> <dfn>Suffering from a custom error</dfn> </dt>
<dd> <p>When a control's <span>custom validity error
message</span> (as set by the element's <code
title="dom-cva-setCustomValidity">setCustomValidity()</code>
method) is not the empty string.</p> </dd>
</dl>
<p class="note">An element can still suffer from these states even
when the element is <span
title="concept-fe-disabled">disabled</span>; thus these states can
be represented in the DOM even if validating the form during
submission wouldn't indicate a problem to the user.</p>
<p>An element <dfn title="concept-fv-valid">satisfies its
constraints</dfn> if it is not suffering from any of the above
<span>validity states</span>.</p>
</div>
<div class="impl">
<h5>Constraint validation</h5>
<p>When the user agent is required to <dfn>statically validate the
constraints</dfn> of <code>form</code> element <var
title="">form</var>, it must run the following steps, which return
either a <i>positive</i> result (all the controls in the form are
valid) or a <i>negative</i> result (there are invalid controls)
along with a (possibly empty) list of elements that are invalid and
for which no script has claimed responsibility:</p>
<ol>
<li><p>Let <var title="">controls</var> be a list of all the <span
title="category-submit">submittable</span> elements whose
<span>form owner</span> is <var title="">form</var>, in <span>tree
order</span>.</p></li>
<li><p>Let <var title="">invalid controls</var> be an initially
empty list of elements.</p></li>
<li>
<p>For each element <var title="">field</var> in <var
title="">controls</var>, in <span>tree order</span>, run the
following substeps:</p>
<ol>
<li><p>If <var title="">field</var> is not a <span>candidate for
constraint validation</span>, then move on to the next
element.</p></li>
<li><p>Otherwise, if <var title="">field</var> <span
title="concept-fv-valid">satisfies its constraints</span>, then
move on to the next element.</p></li>
<li><p>Otherwise, add <var title="">field</var> to <var
title="">invalid controls</var>.</p></li>
</ol>
</li>
<li><p>If <var title="">invalid controls</var> is empty, then
return a <i>positive</i> result and abort these steps.</p></li>
<li><p>Let <var title="">unhandled invalid controls</var> be an
initially empty list of elements.</p></li>
<li>
<p>For each element <var title="">field</var> in <var
title="">invalid controls</var>, if any, in <span>tree
order</span>, run the following substeps:</p>
<ol>
<li><p><span>Fire a simple event</span> named <code
title="event-invalid">invalid</code> that is cancelable at <var
title="">field</var>.</p></li>
<li><p>If the event was not canceled, then add <var
title="">field</var> to <var title="">unhandled invalid
controls</var>.</p></li>
</ol>
</li>
<li><p>Return a <i>negative</i> result with the list of elements in
the <var title="">unhandled invalid controls</var> list.</p></li>
</ol>
<p>If a user agent is to <dfn>interactively validate the
constraints</dfn> of <code>form</code> element <var
title="">form</var>, then the user agent must run the following
steps:</p>
<ol>
<li><p><span>Statically validate the constraints</span> of <var
title="">form</var>, and let <var title="">unhandled invalid
controls</var> be the list of elements returned if the result was
<i>negative</i>.</p></li>
<li><p>If the result was <i>positive</i>, then return that result
and abort these steps.</p></li>
<li><p>Report the problems with the constraints of at least one of
the elements given in <var title="">unhandled invalid
controls</var> to the user. User agents may focus one of those
elements in the process, by running the <span>focusing steps</span>
for that element, and may change the scrolling position of the
document, or perform some other action that brings the element to
the user's attention. User agents may report more than one
constraint violation. User agents may coalesce related constraint
violation reports if appropriate (e.g. if multiple radio buttons in
a <span title="radio button group">group</span> are marked as
required, only one error need be reported). If one of the controls
is not <span>being rendered</span> (e.g. it has the <code
title="attr-hidden">hidden</code> attribute set) then user agents
may report a script error.</p></li>
<li><p>Return a <i>negative</i> result.</p></li>
</ol>
</div>
<h5>The <dfn>constraint validation API</dfn></h5>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-cva-willValidate">willValidate</code></dt>
<dd>
<p>Returns true if the element will be validated when the form is submitted; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-setCustomValidity">setCustomValidity</code>(<var title="">message</var>)</dt>
<dd>
<p>Sets a custom error, so that the element would fail to
validate. The given message is the message to be shown to the user
when reporting the problem to the user.</p>
<p>If the argument is the empty string, clears the custom error.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-valueMissing">valueMissing</code></dt>
<dd>
<p>Returns true if the element has no value but is a required field; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-typeMismatch">typeMismatch</code></dt>
<dd>
<p>Returns true if the element's value is not in the correct syntax; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-patternMismatch">patternMismatch</code></dt>
<dd>
<p>Returns true if the element's value doesn't match the provided pattern; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-tooLong">tooLong</code></dt>
<dd>
<p>Returns true if the element's value is longer than the provided maximum length; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-rangeUnderflow">rangeUnderflow</code></dt>
<dd>
<p>Returns true if the element's value is lower than the provided minimum; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-rangeOverflow">rangeOverflow</code></dt>
<dd>
<p>Returns true if the element's value is higher than the provided maximum; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-stepMismatch">stepMismatch</code></dt>
<dd>
<p>Returns true if the element's value doesn't fit the rules given by the <code title="attr-input-step">step</code> attribute; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-customError">customError</code></dt>
<dd>
<p>Returns true if the element has a custom error; false otherwise.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validity">validity</code> . <code title="dom-validitystate-valid">valid</code></dt>
<dd>
<p>Returns true if the element's value has no validity problems; false otherwise.</p>
</dd>
<dt><var title="">valid</var> = <var title="">element</var> . <code title="dom-cva-checkValidatity">checkValidity</code>()</dt>
<dd>
<p>Returns true if the element's value has no validity problems;
false otherwise. Fires an <code
title="event-invalid">invalid</code> event at the element in the
latter case.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-cva-validationMessage">validationMessage</code></dt>
<dd>
<p>Returns the error message that would be shown to the user if
the element was to be checked for validity.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-cva-willValidate"><code>willValidate</code></dfn>
attribute must return true if an element is a <span>candidate for
constraint validation</span>, and false otherwise (i.e. false if any
conditions are <span title="barred from constraint
validation">barring it from constraint validation</span>).</p>
<p>The <dfn
title="dom-cva-setCustomValidity"><code>setCustomValidity(<var
title="">message</var>)</code></dfn>, when invoked, must set the
<span>custom validity error message</span> to the value of the given
<var title="">message</var> argument.</p>
</div>
<div class="example">
<p>In the following example, a script checks the value of a form
control each time it is edited, and whenever it is not a valid
value, uses the <code
title="dom-cva-setCustomValidity">setCustomValidity()</code> method
to set an appropriate message.</p>
<pre><label>Feeling: <input name=f type="text" oninput="check(this)"></label>
<script>
function check(input) {
if (input.value == "good" ||
input.value == "fine" ||
input.value == "tired") {
input.setCustomValidity('"' + input.value + '" is not a feeling.');
<!-- } else if (input.value == "...") {
input.setCustomValidity('...');
--> } else {
// input is fine -- reset the error message
input.setCustomValidity('');
}
}
</script></pre>
</div>
<div class="impl">
<p>The <dfn title="dom-cva-validity"><code>validity</code></dfn>
attribute must return a <code>ValidityState</code> object that
represents the <span>validity states</span> of the element. This
object is live, and the same object must be returned each time the
element's <code title="dom-cva-validity">validity</code> attribute
is retrieved.</p>
<pre class="idl">interface <dfn>ValidityState</dfn> {
readonly attribute boolean <span title="dom-ValidityState-valueMissing">valueMissing</span>;
readonly attribute boolean <span title="dom-ValidityState-typeMismatch">typeMismatch</span>;
readonly attribute boolean <span title="dom-ValidityState-patternMismatch">patternMismatch</span>;
readonly attribute boolean <span title="dom-ValidityState-tooLong">tooLong</span>;
readonly attribute boolean <span title="dom-ValidityState-rangeUnderflow">rangeUnderflow</span>;
readonly attribute boolean <span title="dom-ValidityState-rangeOverflow">rangeOverflow</span>;
readonly attribute boolean <span title="dom-ValidityState-stepMismatch">stepMismatch</span>;
readonly attribute boolean <span title="dom-ValidityState-customError">customError</span>;
readonly attribute boolean <span title="dom-ValidityState-valid">valid</span>;
};</pre>
<p>A <code>ValidityState</code> object has the following
attributes. On getting, they must return true if the corresponding
condition given in the following list is true, and false
otherwise.</p>
<dl>
<dt><dfn title="dom-ValidityState-valueMissing"><code>valueMissing</code></dfn></dt>
<dd> <p>The control is <span>suffering from being missing</span>.</p> </dd>
<dt><dfn title="dom-ValidityState-typeMismatch"><code>typeMismatch</code></dfn></dt>
<dd> <p>The control is <span>suffering from a type mismatch</span>.</p> </dd>
<dt><dfn title="dom-ValidityState-patternMismatch"><code>patternMismatch</code></dfn></dt>
<dd> <p>The control is <span>suffering from a pattern mismatch</span>.</p> </dd>
<dt><dfn title="dom-ValidityState-tooLong"><code>tooLong</code></dfn></dt>
<dd> <p>The control is <span>suffering from being too long</span>.</p> </dd>
<dt><dfn title="dom-ValidityState-rangeUnderflow"><code>rangeUnderflow</code></dfn></dt>
<dd> <p>The control is <span>suffering from an underflow</span>.</p> </dd>
<dt><dfn title="dom-ValidityState-rangeOverflow"><code>rangeOverflow</code></dfn></dt>
<dd> <p>The control is <span>suffering from an overflow</span>.</p> </dd>
<dt><dfn title="dom-ValidityState-stepMismatch"><code>stepMismatch</code></dfn></dt>
<dd> <p>The control is <span>suffering from a step mismatch</span>.</p> </dd>
<dt><dfn title="dom-ValidityState-customError"><code>customError</code></dfn></dt>
<dd> <p>The control is <span>suffering from a custom error</span>.</p> </dd>
<dt><dfn title="dom-ValidityState-valid"><code>valid</code></dfn></dt>
<dd> <p>None of the other conditions are true.</p> </dd>
</dl>
<p>When the <dfn
title="dom-cva-checkValidatity"><code>checkValidity()</code></dfn>
method is invoked, if the element is a <span>candidate for
constraint validation</span> and does not <span
title="concept-fv-valid">satisfy its constraints</span>, the user
agent must <span>fire a simple event</span> named <code
title="event-invalid">invalid</code> that is cancelable (but in this
case has no default action) at the element and return
false. Otherwise, it must only return true without doing anything
else.</p>
<p>The <dfn
title="dom-cva-validationMessage"><code>validationMessage</code></dfn>
attribute must return the empty string if the element is not a
<span>candidate for constraint validation</span> or if it is one but
it <span title="concept-fv-valid">satisfies its constraints</span>;
otherwise, it must return a suitably localized message that the user
agent would show the user if this were the only form with a validity
constraint problem. If the element is a <span>candidate for
constraint validation</span> and is <span>suffering from a custom
error</span>, then the <span>custom validity error message</span>
should be present in the return value.</p>
</div>
<div class="impl">
<h5>Security</h5>
<p>Servers should not rely on client-side validation. Client-side
validation can be intentionally bypassed by hostile users, and
unintentionally bypassed by users of older user agents or automated
tools that do not implement these features. The constraint
validation features are only intended to improve the user
experience, not to provide any kind of security mechanism.</p>
</div>
<h4><dfn>Form submission</dfn></h4>
<div class="impl">
<h5>Introduction</h5>
</div>
<p><i>This section is non-normative.</i></p>
<p>When forms are submitted, the data in the form is converted into
the form specified by the <span
title="concept-fs-enctype">enctype</span>, and then sent to the
destination specified by the <span
title="concept-fs-action">action</span> using the given <span
title="concept-fs-method">method</span>.</p>
<p>For example, take the following form:</p>
<pre><form action="/find.cgi" method=get>
<input type=text name=t>
<input type=search name=q>
<input type=submit>
</form></pre>
<p>If the user types in "cats" in the first field and "fur" in the
second, and then hits the submit button, then the user agent will
load <code title="">/find.cgi?t=cats&q=fur</code>.</p>
<p>On the other hand, consider this form:</p>
<pre><form action="/find.cgi" method=post enctype="multipart/form-data">
<input type=text name=t>
<input type=search name=q>
<input type=submit>
</form></pre>
<p>Given the same user input, the result on submission is quite
different: the user agent instead does an HTTP POST to the given
URL, with as the entity body something like the following text:</p>
<pre>------kYFrd4jNJEgCervE
Content-Disposition: form-data; name="t"
cats
------kYFrd4jNJEgCervE
Content-Disposition: form-data; name="q"
fur
------kYFrd4jNJEgCervE--</pre>
<div class="impl">
<h5>Implicit submission</h5>
<p>User agents may establish a <span
title="concept-button">button</span> in each form as being the
form's <dfn>default button</dfn>. This should be the first <span
title="concept-submit-button">submit button</span> in <span>tree
order</span> whose <span>form owner</span> is that <code>form</code>
element, but user agents may pick another button if another would be
more appropriate for the platform. If the platform supports letting
the user submit a form implicitly (for example, on some platforms
hitting the "enter" key while a text field is focused implicitly
submits the form), then doing so must cause the form's <span>default
button</span>'s <span>activation behavior</span>, if any, to be
run.</p>
<p class="note">Consequently, if the <span>default button</span> is
<span title="concept-fe-disabled">disabled</span>, the form is not
submitted when such an implicit submission mechanism is used. (A
button has no <span>activation behavior</span> when disabled.)</p>
<p>If the form has no <span title="concept-submit-button">submit
button</span>, then the implicit submission mechanism must just
<span title="concept-form-submit">submit</span> the
<code>form</code> element from the <code>form</code> element
itself.</p>
</div>
<div class="impl">
<h5>Form submission algorithm</h5>
<p>When a form <var title="">form</var> is <dfn
title="concept-form-submit">submitted</dfn> from an element <var
title="">submitter</var> (typically a button), optionally with a
<var title="">scripted-submit</var> flag set, the user agent must
run the following steps:</p>
<ol>
<li id="sandboxSubmitBlocked"><p>If <var title="">form</var> is in
a <code>Document</code> that has no associated <span>browsing
context</span> or whose <span>browsing context</span> has its
<span>sandboxed forms browsing context flag</span> set, then abort
these steps without doing anything.</p></li>
<li><p>If <var title="">form</var> is already being submitted
(i.e. the form was <span
title="concept-form-submit">submitted</span> again while processing
the events fired from the next two steps, probably from a script
redundantly calling the <code
title="dom-form-submit">submit()</code> method on <var
title="">form</var>), then abort these steps. This doesn't affect
the earlier instance of this algorithm.</p></li>
<!-- lock (implicit in previous step) -->
<li><p>If the <var title="">scripted-submit</var> flag is not set,
and the <var title="">submitter</var> element's <span
title="concept-fs-novalidate">no-validate state</span> is false,
then <span>interactively validate the constraints</span> of <var
title="">form</var> and examine the result: if the result is
negative (the constraint validation concluded that there were
invalid fields and probably informed the user of this) then abort
these steps.</p></li>
<li><p>If the <var title="">scripted-submit</var> flag is not set,
then <span>fire a simple event</span> that is cancelable named
<code title="event-submit">submit</code>, at <var
title="">form</var>. If the event's default action is prevented
(i.e. if the event is canceled) then abort these steps. Otherwise,
continue (effectively the default action is to perform the
submission).</p></li>
<!-- if you add any steps between the "lock" and "unlock" lines,
make sure to update the step immediately before the "lock" line -->
<!-- unlock -->
<li><p>Let <var title="">controls</var> be a list of all the <span
title="category-submit">submittable</span> elements whose
<span>form owner</span> is <var title="">form</var>, in <span>tree
order</span>.</p></li>
<li><p>Let the <var title="">form data set</var> be a list of
name-value-type tuples, initially empty.</p></li>
<li id="constructing-form-data-set">
<p><strong>Constructing the form data set</strong>. For each
element <var title="">field</var> in <var title="">controls</var>,
in <span>tree order</span>, run the following substeps:</p>
<ol>
<li>
<p>If any of the following conditions are met, then skip these
substeps for this element:</p>
<ul>
<li>The <var title="">field</var> element has a
<code>datalist</code> element ancestor.</li>
<li>The <var title="">field</var> element is <span
title="concept-fe-disabled">disabled</span>.</li>
<li>The <var title="">field</var> element is a <span
title="concept-button">button</span> but it is not <var
title="">submitter</var>.</li>
<li>The <var title="">field</var> element is an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-checkbox">Checkbox</span> state and
whose <span title="concept-fe-checked">checkedness</span> is
false.</li>
<li>The <var title="">field</var> element is an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-radio">Radio Button</span> state and
whose <span title="concept-fe-checked">checkedness</span> is
false.</li>
<li>The <var title="">field</var> element is an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-file">File Upload</span> state but
the control does not have any files selected.</li>
<li>The <var title="">field</var> element is an
<code>object</code> element that is not using a
<span>plugin</span>.</li>
</ul>
<p>Otherwise, process <var title="">field</var> as follows:</p>
</li>
<li><p>Let <var title="">type</var> be the value of the <code
title="">type</code> IDL attribute of <var
title="">field</var>.</p></li> <!-- if the field is an <object>
element, this will get ignored. -->
<li>
<p>If the <var title="">field</var> element is an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-image">Image Button</span> state,
then run these further nested substeps:</p>
<ol>
<li><p>If the <var title="">field</var> element has an <code
title="attr-fe-name">name</code> attribute specified and value
is not the empty string, let <var title="">name</var> be that
value followed by a single U+002E FULL STOP character
(.). Otherwise, let <var title="">name</var> be the empty
string.</p></li>
<li><p>Let <var title="">name<sub title="">x</sub></var> be the
string consisting of the concatenation of <var
title="">name</var> and a single U+0078 LATIN SMALL LETTER X
character (x).</p></li>
<li><p>Let <var title="">name<sub title="">y</sub></var> be the
string consisting of the concatenation of <var
title="">name</var> and a single U+0079 LATIN SMALL LETTER Y
character (y).</p></li>
<li><p>The <var title="">field</var> element is <var
title="">submitter</var>, and before this algorithm was invoked
the user <span
title="concept-input-type-image-coordinate">indicated a
coordinate</span>. Let <var title="">x</var> be the <var
title="">x</var>-component of the coordinate selected by the
user, and let <var title="">y</var> be the <var
title="">y</var>-component of the coordinate selected by the
user.</p></li>
<li><p>Append an entry in the <var title="">form data set</var>
with the name <var title="">name<sub title="">x</sub></var>,
the value <var title="">x</var>, and the type <var
title="">type</var>.</p></li>
<li><p>Append an entry in the <var title="">form data set</var>
with the name <var title="">name<sub title="">y</sub></var> and
the value <var title="">y</var>, and the type <var
title="">type</var>.</p></li>
<li><p>Skip the remaining substeps for this element: if there
are any more elements in <var title="">controls</var>, return
to the top of the <a
href="#constructing-form-data-set">constructing the form data
set</a> step, otherwise, jump to the next step in the overall
form submission algorithm.</p></li>
</ol>
</li>
<li><p>If the <var title="">field</var> element does not have a
<code title="attr-fe-name">name</code> attribute specified, or
its <code title="attr-fe-name">name</code> attribute's value is
the empty string, skip these substeps for this element: if there
are any more elements in <var title="">controls</var>, return to
the top of the <a href="#constructing-form-data-set">constructing
the form data set</a> step, otherwise, jump to the next step in
the overall form submission algorithm.</p></li>
<li><p>Let <var title="">name</var> be the value of the <var
title="">field</var> element's <code
title="attr-fe-name">name</code> attribute.</p></li>
<li><p>If the <var title="">field</var> element is a
<code>select</code> element, then for each <code>option</code>
element in the <code>select</code> element whose <span
title="concept-option-selectedness">selectedness</span> is true,
append an entry in the <var title="">form data set</var> with the
<var title="">name</var> as the name, the <span
title="concept-option-value">value</span> of the
<code>option</code> element as the value, and <var
title="">type</var> as the type.</p></li>
<li>
<p>Otherwise, if the <var title="">field</var> element is an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-checkbox">Checkbox</span> state or the
<span title="attr-input-type-radio">Radio Button</span> state,
then run these further nested substeps:</p>
<ol>
<li><p>If the <var title="">field</var> element has a <code
title="attr-input-value">value</code> attribute specified, then
let <var title="">value</var> be the value of that attribute;
otherwise, let <var title="">value</var> be the string
"<code title="">on</code>".</p></li>
<li><p>Append an entry in the <var title="">form data set</var>
with <var title="">name</var> as the name, <var
title="">value</var> as the value, and <var title="">type</var>
as the type.</p></li>
</ol>
</li>
<li><p>Otherwise, if the <var title="">field</var> element is an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-file">File Upload</span> state, then for
each file <span
title="concept-input-type-file-selected">selected</span> in the
<code>input</code> element, append an entry in the <var
title="">form data set</var> with the <var title="">name</var> as
the name, the file (consisting of the name, the type, and the
body) as the value, and <var title="">type</var> as the
type.</p></li>
<li><p>Otherwise, if the <var title="">field</var> element is an
<code>object</code> element: try to obtain a form submission
value from the <span>plugin</span><!-- using NPAPI's
NPP_GetValue() entry point with the NPPVformValue variable -->,
and if that is successful, append an entry in the <var
title="">form data set</var> with <var title="">name</var> as the
name, the returned form submission value as the value, and the
string "<code title="">object</code>" as the type.</p></li>
<li><p>Otherwise, append an entry in the <var title="">form data
set</var> with <var title="">name</var> as the name, the <span
title="concept-fe-value">value</span> of the <var
title="">field</var> element as the value, and <var
title="">type</var> as the type.</p></li>
</ol>
</li>
<li><p>Let <var title="">action</var> be the <var
title="">submitter</var> element's <span
title="concept-fs-action">action</span>.</p></li>
<li>
<p>If <var title="">action</var> is the empty string, let <var
title="">action</var> be <span>the document's address</span>.</p>
<p class="note">This step is a <span>willful violation</span> of
RFC 3986, which would require base URL processing here. This
violation is motivated by a desire for compatibility with legacy
content. <a href="#refsRFC3986">[RFC3986]</a></p>
<!-- Don't ask me why. But that's what IE does. It even treats
action="" differently from action=" " or action="#" (the latter
two resolve to the base URL, the first one resolves to the doc
URL). And other browsers concur. It is even required, see e.g.
http://bugs.webkit.org/show_bug.cgi?id=7763
https://bugzilla.mozilla.org/show_bug.cgi?id=297761
-->
</li>
<li><p><span title="resolve a url">Resolve</span> the
<span>URL</span> <var title="">action</var>, relative to the <var
title="">submitter</var> element. If this fails, abort these
steps. Otherwise, let <var title="">action</var> be the resulting
<span>absolute URL</span>.</p></li>
<li><p>Let <var title="">scheme</var> be the <span
title="url-scheme"><scheme></span> of the resulting
<span>absolute URL</span>.</p></li>
<li><p>Let <var title="">enctype</var> be the <var
title="">submitter</var> element's <span
title="concept-fs-enctype">enctype</span>.</p></li>
<li><p>Let <var title="">method</var> be the <var
title="">submitter</var> element's <span
title="concept-fs-method">method</span>.</p></li>
<li><p>Let <var title="">target</var> be the <var
title="">submitter</var> element's <span
title="concept-fs-target">target</span>.</p></li>
<li>
<p>Select the appropriate row in the table below based on the
value of <var title="">scheme</var> as given by the first cell of
each row. Then, select the appropriate cell on that row based on
the value of <var title="">method</var> as given in the first cell
of each column. Then, jump to the steps named in that cell and
defined below the table.</p>
<table>
<thead>
<tr>
<td>
<th> <span title="attr-fs-method-GET">GET</span>
<th> <span title="attr-fs-method-POST">POST</span>
<th> <span title="attr-fs-method-PUT">PUT</span>
<th> <span title="attr-fs-method-DELETE">DELETE</span>
<tbody>
<tr>
<th> <code title="">http</code>
<td> <span title="submit-mutate-action">Mutate action</span>
<td> <span title="submit-body">Submit as entity body</span>
<td> <span title="submit-body">Submit as entity body</span>
<td> <span title="submit-delete-action">Delete action</span>
<tr>
<th> <code title="">https</code>
<td> <span title="submit-mutate-action">Mutate action</span>
<td> <span title="submit-body">Submit as entity body</span>
<td> <span title="submit-body">Submit as entity body</span>
<td> <span title="submit-delete-action">Delete action</span>
<tr>
<th> <code title="">ftp</code>
<td> <span title="submit-get-action">Get action</span>
<td> <span title="submit-get-action">Get action</span>
<td> <span title="submit-get-action">Get action</span>
<td> <span title="submit-get-action">Get action</span>
<tr>
<th> <code title="">javascript</code>
<td> <span title="submit-get-action">Get action</span>
<td> <span title="submit-get-action">Get action</span>
<td> <span title="submit-get-action">Get action</span>
<td> <span title="submit-get-action">Get action</span>
<tr>
<th> <code title="">data</code>
<td> <span title="submit-get-action">Get action</span>
<td> <span title="submit-data-post">Post to data:</span>
<td> <span title="submit-data-put">Put to data:</span>
<td> <span title="submit-get-action">Get action</span>
<tr>
<th> <code title="">mailto</code>
<td> <span title="submit-mailto-headers">Mail with headers</span>
<td> <span title="submit-mailto-body">Mail as body</span>
<td> <span title="submit-mailto-headers">Mail with headers</span>
<td> <span title="submit-mailto-headers">Mail with headers</span>
</table>
<p>If <var title="">scheme</var> is not one of those listed in
this table, then the behavior is not defined by this
specification. User agents should, in the absence of another
specification defining this, act in a manner analogous to that
defined in this specification for similar schemes.</p>
<p>The behaviors are as follows:</p>
<dl>
<dt><dfn title="submit-mutate-action">Mutate action</dfn>
<dd>
<p>Let <var title="">query</var> be the result of encoding the
<var title="">form data set</var> using the <span><code
title="">application/x-www-form-urlencoded</code> encoding
algorithm</span>, interpreted as a US-ASCII string.</p>
<p>Let <var title="">destination</var> be a new <span>URL</span>
that is equal to the <var title="">action</var> except that its
<span title="url-query"><query></span> component is
replaced by <var title="">query</var> (adding a U+003F QUESTION
MARK character (?) if appropriate).</p>
<p>Let <var title="">target browsing context</var> be <span>the
form submission target browsing context</span>.</p>
<p><span>Navigate</span> <var title="">target browsing
context</var> to <var title="">destination</var>. If <var
title="">target browsing context</var> was newly created for
this purpose by the steps above, then it must be navigated with
<span>replacement enabled</span>.</p>
</dd>
<dt><dfn title="submit-body">Submit as entity body</dfn>
<dd>
<p>Let <var title="">entity body</var> be the result of encoding
the <var title="">form data set</var> using the
<span>appropriate form encoding algorithm</span>.</p>
<p>Let <var title="">target browsing context</var> be <span>the
form submission target browsing context</span>.</p>
<p>Let <var title="">MIME type</var> be determined as
follows:</p>
<dl>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-urlencoded">application/x-www-form-urlencoded</code></dt>
<dd>Let <var title="">MIME type</var> be "<code
title="">application/x-www-form-urlencoded</code>".</dd>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-formdata">multipart/form-data</code></dt>
<dd>Let <var title="">MIME type</var> be "<code
title="">multipart/form-data</code>".</dd>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-text">text/plain</code></dt>
<dd>Let <var title="">MIME type</var> be "<code title="">text/plain</code>".</dd>
</dl>
<p>If <var title="">method</var> is anything but GET or POST,
and the <span>origin</span> of <var title="">action</var> is not
the <span>same origin</span> as that of the <code>form</code>
element's <code>Document</code>, then abort these steps.</p>
<!-- CORS, one day -->
<p>Otherwise, <span>navigate</span> <var title="">target
browsing context</var> to <var title="">action</var> using the
HTTP method given by <var title="">method</var> and with <var
title="">entity body</var> as the entity body, of type <var
title="">MIME type</var>. If <var title="">target browsing
context</var> was newly created for this purpose by the steps
above, then it must be navigated with <span>replacement
enabled</span>.</p>
</dd>
<dt><dfn title="submit-delete-action">Delete action</dfn>
<dd>
<p>Let <var title="">target browsing context</var> be <span>the
form submission target browsing context</span>.</p>
<p>If the <span>origin</span> of <var title="">action</var> is
not the <span>same origin</span> as that of the
<code>form</code> element's <code>Document</code>, then abort
these steps.</p> <!-- CORS, one day -->
<p>Otherwise, <span>navigate</span> <var title="">target
browsing context</var> to <var title="">action</var> using the
DELETE method. If <var title="">target browsing context</var>
was newly created for this purpose by the steps above, then it
must be navigated with <span>replacement enabled</span>.</p>
</dd>
<dt><dfn title="submit-get-action">Get action</dfn>
<dd>
<p>Let <var title="">target browsing context</var> be <span>the
form submission target browsing context</span>.</p>
<p><span>Navigate</span> <var title="">target browsing
context</var> to <var title="">action</var>. If <var
title="">target browsing context</var> was newly created for
this purpose by the steps above, then it must be navigated with
<span>replacement enabled</span>.</p>
</dd>
<dt><dfn title="submit-data-post">Post to data:</dfn>
<dd>
<p>Let <var title="">data</var> be the result of encoding the
<var title="">form data set</var> using the <span>appropriate
form encoding algorithm</span>.</p>
<p>If <var title="">action</var> contains the string "<code
title="">%%%%</code>" (four U+0025 PERCENT SIGN characters),
then %-escape all bytes in <var title="">data</var> that, if
interpreted as US-ASCII, do not match the <code
title="">unreserved</code> production in the URI Generic Syntax,
and then, treating the result as a US-ASCII string, further
%-escape all the U+0025 PERCENT SIGN characters in the resulting
string and replace the first occurrence of "<code
title="">%%%%</code>" in <var title="">action</var> with the
resulting double-escaped string. <a
href="#refsRFC3986">[RFC3986]</a></p>
<p>Otherwise, if <var title="">action</var> contains the string
"<code title="">%%</code>" (two U+0025 PERCENT SIGN characters
in a row, but not four), then %-escape all characters in <var
title="">data</var> that, if interpreted as US-ASCII, do not
match the <code title="">unreserved</code> production in the URI
Generic Syntax, and then, treating the result as a US-ASCII
string, replace the first occurrence of "<code
title="">%%</code>" in <var title="">action</var> with the
resulting escaped string. <a
href="#refsRFC3986">[RFC3986]</a></p>
<p>Let <var title="">target browsing context</var> be <span>the
form submission target browsing context</span>.</p>
<p><span>Navigate</span> <var title="">target browsing
context</var> to the potentially modified <var
title="">action</var>. If <var title="">target browsing
context</var> was newly created for this purpose by the steps
above, then it must be navigated with <span>replacement
enabled</span>.</p>
</dd>
<dt><dfn title="submit-data-put">Put to data:</dfn>
<dd>
<p>Let <var title="">data</var> be the result of encoding the
<var title="">form data set</var> using the <span>appropriate
form encoding algorithm</span>.</p>
<p>Let <var title="">MIME type</var> be determined as
follows:</p>
<dl>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-urlencoded">application/x-www-form-urlencoded</code></dt>
<dd>Let <var title="">MIME type</var> be "<code
title="">application/x-www-form-urlencoded</code>".</dd>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-formdata">multipart/form-data</code></dt>
<dd>Let <var title="">MIME type</var> be "<code
title="">multipart/form-data</code>".</dd>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-text">text/plain</code></dt>
<dd>Let <var title="">MIME type</var> be "<code title="">text/plain</code>".</dd>
</dl>
<p>Let <var title="">destination</var> be the result of
concatenating the following:</p>
<ol class="brief">
<li>The string "<code title="">data:</code>".</li>
<li>The value of <var title="">MIME type</var>.</li>
<li>The string "<code title="">;base64,</code>".</li>
<li>A base-64 encoded representation of <var
title="">data</var>. <a href="#refsRFC2045">[RFC2045]</a></li>
</ol>
<p>Let <var title="">target browsing context</var> be <span>the
form submission target browsing context</span>.</p>
<p><span>Navigate</span> <var title="">target browsing
context</var> to <var title="">destination</var>. If <var
title="">target browsing context</var> was newly created for
this purpose by the steps above, then it must be navigated with
<span>replacement enabled</span>.</p>
</dd>
<dt><dfn title="submit-mailto-headers">Mail with headers</dfn>
<dd>
<p>Let <var title="">headers</var> be the resulting encoding the
<var title="">form data set</var> using the <span><code
title="">application/x-www-form-urlencoded</code> encoding
algorithm</span>, interpreted as a US-ASCII string.</p>
<p>Replace occurrences of U+002B PLUS SIGN characters (+) in
<var title="">headers</var> with the string "<code
title="">%20</code>".</p>
<p>Let <var title="">destination</var> consist of all the
characters from the first character in <var
title="">action</var> to the character immediately before the
first U+003F QUESTION MARK character (?), if any, or the end of
the string if there are none.</p>
<p>Append a single U+003F QUESTION MARK character (?) to <var
title="">destination</var>.</p>
<p>Append <var title="">headers</var> to <var
title="">destination</var>.</p>
<p>Let <var title="">target browsing context</var> be <span>the
form submission target browsing context</span>.</p>
<p><span>Navigate</span> <var title="">target browsing
context</var> to <var title="">destination</var>. If <var
title="">target browsing context</var> was newly created for
this purpose by the steps above, then it must be navigated with
<span>replacement enabled</span>.</p>
</dd>
<dt><dfn title="submit-mailto-body">Mail as body</dfn>
<dd>
<p>Let <var title="">body</var> be the resulting encoding the
<var title="">form data set</var> using the <span>appropriate
form encoding algorithm</span> and then %-escaping all the bytes
in the resulting byte string that, when interpreted as US-ASCII,
do not match the <code title="">unreserved</code> production in
the URI Generic Syntax. <a href="#refsRFC3986">[RFC3986]</a></p>
<p>Let <var title="">destination</var> have the same value as
<var title="">action</var>.</p>
<p>If <var title="">destination</var> does not contain a U+003F
QUESTION MARK character (?), append a single U+003F QUESTION
MARK character (?) to <var
title="">destination</var>. Otherwise, append a single U+0026
AMPERSAND character (&).</p>
<p>Append the string "<code title="">body=</code>" to <var
title="">destination</var>.</p>
<p>Append <var title="">body</var>, interpreted as a US-ASCII
string, to <var title="">destination</var>.</p>
<p>Let <var title="">target browsing context</var> be <span>the
form submission target browsing context</span>.</p>
<p><span>Navigate</span> <var title="">target browsing
context</var> to <var title="">destination</var>. If <var
title="">target browsing context</var> was newly created for
this purpose by the steps above, then it must be navigated with
<span>replacement enabled</span>.</p>
</dd>
</dl>
<p><dfn>The form submission target browsing context</dfn> is
obtained, when needed by the behaviors described above, as
follows: If the user indicated a specific <span>browsing
context</span> to use when submitting the form, then that is the
target browsing context. Otherwise, apply <span>the rules for
choosing a browsing context given a browsing context name</span>
using <var title="">target</var> as the name and the
<span>browsing context</span> of <var title="">form</var> as the
context in which the algorithm is executed; the resulting
<span>browsing context</span> is the target browsing context.</p>
<p>The <dfn>appropriate form encoding algorithm</dfn> is
determined as follows:</p>
<dl>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-urlencoded">application/x-www-form-urlencoded</code></dt>
<dd>Use the <span><code
title="">application/x-www-form-urlencoded</code> encoding
algorithm</span>.</dd>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-formdata">multipart/form-data</code></dt>
<dd>Use the <span><code
title="">multipart/form-data</code> encoding
algorithm</span>.</dd>
<dt>If <var title="">enctype</var> is <code title="attr-fs-enctype-text">text/plain</code></dt>
<dd>Use the <span><code title="">text/plain</code> encoding
algorithm</span>.</dd>
</dl>
</li>
</ol>
</div>
<div class="impl">
<h5>URL-encoded form data</h5>
<p>The <dfn><code
title="">application/x-www-form-urlencoded</code> encoding
algorithm</dfn> is as follows:</p>
<ol>
<li><p>Let <var title="">result</var> be the empty string.</p></li>
<li>
<p>If the <code>form</code> element has an <code
title="attr-form-accept-charset">accept-charset</code> attribute,
then, taking into account the characters found in the <var
title="">form data set</var>'s names and values, and the character
encodings supported by the user agent, select a character encoding
from the list given in the <code>form</code>'s <code
title="attr-form-accept-charset">accept-charset</code> attribute
that is an <span>ASCII-compatible character encoding</span>. If
none of the encodings are supported, then let the selected
character encoding be UTF-8.</p>
<p>Otherwise, if the <span>document's character encoding</span> is
an <span>ASCII-compatible character encoding</span>, then that is
the selected character encoding.</p>
<p>Otherwise, let the selected character encoding be UTF-8.</p>
</li>
<li><p>Let <var title="">charset</var> be the <span>preferred MIME
name</span> of the selected character encoding.</p></li>
<li>
<p>For each entry in the <var title="">form data set</var>,
perform these substeps:</p>
<ol>
<li><p>If the entry's name is "<code title="">_charset_</code>"
and its type is "<code title="">hidden</code>", replace its value
with <var title="">charset</var>.</p></li>
<li><p>If the entry's type is "<code title="">file</code>",
replace its value with the file's filename only.</p></li>
<li><p>For each character in the entry's name and value that
cannot be expressed using the selected character encoding,
replace the character by a string consisting of a U+0026
AMPERSAND character (&), a U+0023 NUMBER SIGN character (#),
one or more characters in the range U+0030 DIGIT ZERO (0) to
U+0039 DIGIT NINE (9) representing the Unicode code point of the
character in base ten, and finally a U+003B SEMICOLON character
(;).</p></li><!-- we should say it should be the shortest
possible string, no leading zeros. this whole step as asinine,
though, so... -->
<li>
<p>For each character in the entry's name and value, apply the
following subsubsteps:</p>
<ol>
<!-- * - . _ 0-9 a-z A-Z -->
<li><p>If the character isn't in the range U+0020, U+002A,
U+002D, U+002E, U+0030 to U+0039, U+0041 to U+005A, U+005F,
U+0061 to U+007A then replace the character with a string
formed as follows: Start with the empty string, and then,
taking each byte of the character when expressed in the
selected character encoding in turn, append to the string a
U+0025 PERCENT SIGN character (%) followed by two characters in
the ranges U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) and
U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F
representing the hexadecimal value of the byte (zero-padded if
necessary).</p></li>
<li><p>If the character is a U+0020 SPACE character, replace it
with a single U+002B PLUS SIGN character (+).</p></li>
</ol>
</li>
<li><p>If the entry's name is "<code title="">isindex</code>",
its type is "<code title="">text</code>", and this is the first
entry in the <var title="">form data set</var>, then append the
value to <var title="">result</var> and skip the rest of the
substeps for this entry, moving on to the next entry, if any, or
the next step in the overall algorithm otherwise.</p></li>
<li><p>If this is not the first entry, append a single U+0026
AMPERSAND character (&) to <var
title="">result</var>.</p></li>
<li><p>Append the entry's name to <var
title="">result</var>.</p></li>
<li><p>Append a single U+003D EQUALS SIGN character (=) to <var
title="">result</var>.</p></li>
<li><p>Append the entry's value to <var
title="">result</var>.</p></li>
</ol>
</li>
<li><p>Encode <var title="">result</var> as US-ASCII and return the
resulting byte stream.</p></li>
</ol>
</div>
<div class="impl">
<h5>Multipart form data</h5>
<p>The <dfn><code title="">multipart/form-data</code> encoding
algorithm</dfn> is to encode the <var title="">form data set</var>
using the rules described by RFC2388, <cite>Returning Values from
Forms: <code title="">multipart/form-data</code></cite>, and return
the resulting byte stream. <a href="#refsRFC2388">[RFC2388]</a></p>
<p>Each entry in the <var title="">form data set</var> is a
<i>field</i>, the name of the entry is the <i>field name</i> and the
value of the entry is the <i>field value</i>.</p>
<p>The order of parts must be the same as the order of fields in the
<var title="">form data set</var>. Multiple entries with the same
name must be treated as distinct fields.</p>
</div>
<div class="impl">
<h5>Plain text form data</h5>
<p>The <dfn><code title="">text/plain</code> encoding
algorithm</dfn> is as follows:</p>
<ol>
<li><p>Let <var title="">result</var> be the empty string.</p></li>
<li>
<!-- this is different from application/x-www-form-urlencoded in
that it isn't limited to ASCII-compatible encodings -->
<p>If the <code>form</code> element has an <code
title="attr-form-accept-charset">accept-charset</code> attribute,
then, taking into account the characters found in the <var
title="">form data set</var>'s names and values, and the character
encodings supported by the user agent, select a character encoding
from the list given in the <code>form</code>'s <code
title="attr-form-accept-charset">accept-charset</code>
attribute. If none of the encodings are supported, then let the
selected character encoding be UTF-8.</p>
<p>Otherwise, the selected character encoding is the
<span>document's character encoding</span>.</p>
</li>
<li><p>Let <var title="">charset</var> be the <span>preferred MIME
name</span> of the selected character encoding.</p></li>
<li><p>If the entry's name is "<code title="">_charset_</code>" and
its type is "<code title="">hidden</code>", replace its value with
<var title="">charset</var>.</p></li>
<li><p>If the entry's type is "<code title="">file</code>", replace
its value with the file's filename only.</p></li>
<li>
<p>For each entry in the <var title="">form data set</var>,
perform these substeps:</p>
<ol>
<li><p>Append the entry's name to <var
title="">result</var>.</p></li>
<li><p>Append a single U+003D EQUALS SIGN character (=) to <var
title="">result</var>.</p></li>
<li><p>Append the entry's value to <var
title="">result</var>.</p></li>
<li><p>Append a U+000D CARRIAGE RETURN (CR) U+000A LINE FEED (LF)
character pair to <var title="">result</var>.</p></li>
</ol>
</li>
<li><p>Encode <var title="">result</var> using the selected
character encoding and return the resulting byte stream.</p></li>
</ol>
</div>
<div class="impl">
<h4>Resetting a form</h4>
<p>When a form <var title="">form</var> is <dfn
title="concept-form-reset">reset</dfn>, the user agent must
<span>fire a simple event</span> named <code
title="event-reset">reset</code>, that is cancelable, at <var
title="">form</var>, and then, if that event is not canceled, must
invoke the <span title="concept-form-reset-control">reset
algorithm</span> of each <span
title="category-reset">resettable</span> elements whose <span>form
owner</span> is <var title="">form</var>, and <span>broadcast <code
title="event-formchange">formchange</code> events</span> from <var
title="">form</var>.</p>
<p>Each <span title="category-reset">resettable</span> element
defines its own <dfn title="concept-form-reset-control">reset
algorithm</dfn>. Changes made to form controls as part of these
algorithms do not count as changes caused by the user (and thus,
e.g., do not cause <code title="event-input">input</code> events to
fire).</p>
</div>
<div class="impl">
<h4>Event dispatch</h4>
<p>When the user agent is to <dfn>broadcast <code
title="event-forminput">forminput</code> events</dfn> or
<dfn>broadcast <code title="event-formchange">formchange</code>
events</dfn> from a <code>form</code> element <var
title="">form</var>, it must run the following steps:</p>
<ol>
<li><p>Let <var title="">controls</var> be a list of all the <span
title="category-reset">resettable</span> elements whose <span>form
owner</span> is <var title="">form</var>.</p></li>
<li>If the user agent was to <span>broadcast <code
title="event-forminput">forminput</code> events</span>, let <var
title="">event name</var> be <code
title="event-forminput">forminput</code>. Otherwise the user agent
was to <span>broadcast <code
title="event-formchange">formchange</code> events</span>; let <var
title="">event name</var> be <code
title="event-formchange">formchange</code>.</li>
<li><p>For each element in <var title="">controls</var>, in
<span>tree order</span>, <span>fire a simple event</span> named
<var title="">event name</var> at the element.</p></li>
</ol>
</div>
<h3 id="interactive-elements">Interactive elements</h3>
<h4>The <dfn><code>details</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Sectioning root</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Optionally one <code>dt</code> element, followed by one <code>dd</code> element.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-details-open">open</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLDetailsElement</dfn> : <span>HTMLElement</span> {
attribute boolean <span title="dom-details-open">open</span>;
};</pre>
</dd>
</dl>
<p>The <code>details</code> element <span>represents</span> a
disclosure widget from which the user can obtain additional
information or controls.</p>
<p class="note">The <code>details</code> element is not appropriate
for footnotes. Please see <a href="#footnotes">the section on
footnotes</a> for details on how to mark up footnotes.</p>
<p>The <span class="impl">first</span> <code>dt</code> element child
of the element, if any, <span>represents</span> the summary of the
details. <span class="impl">If there is no child <code>dt</code>
element, the user agent should provide its own legend
(e.g. "Details").</span></p>
<p>The <span class="impl">first</span> <code>dd</code> element child
of the element<span class="impl">, if any,</span>
<span>represents</span> the details. <span class="impl">If there is
no child <code>dd</code> element, then there are no
details.</span></p>
<p>The <dfn title="attr-details-open"><code>open</code></dfn>
content attribute is a <span>boolean attribute</span>. If present,
it indicates that the details are to be shown to the user. If the
attribute is absent, the details are not to be shown.</p>
<div class="impl">
<p>If the attribute is removed, then the details should be
hidden. If the attribute is added, the details should be shown.</p>
<p>The user agent should allow the user to request that the details
be shown or hidden. To honor a request for the details to be shown,
the user agent must set the <code
title="attr-details-open">open</code> attribute on the element to
the value <code title="">open</code>. To honor a request for the
details to be hidden, the user agent must remove the <code
title="attr-details-open">open</code> attribute from the
element.</p>
<p>The <dfn title="dom-details-open"><code>open</code></dfn>
attribute must <span>reflect</span> the <code
title="attr-details-open">open</code> content attribute.</p>
</div>
<div class="example">
<p>The following example shows the <code>details</code> element
being used to hide technical details in a progress report.</p>
<pre><section class="progress window">
<h1>Copying "Really Achieving Your Childhood Dreams"</h1>
<details>
<dt>Copying... <progress max="375505392" value="97543282"></progress> 25%</dt>
<dd>
<dl>
<dt>Transfer rate:</dt> <dd>452KB/s</dd>
<dt>Local filename:</dt> <dd>/home/rpausch/raycd.m4v</dd>
<dt>Remote filename:</dt> <dd>/var/www/lectures/raycd.m4v</dd>
<dt>Duration:</dt> <dd>01:16:27</dd>
<dt>Color profile:</dt> <dd>SD (6-1-6)</dd>
<dt>Dimensions:</dt> <dd>320×240</dd>
</dl>
</dd>
</details>
</section></pre>
</div>
<!-- v2DATAGRID
<h4 id="datagrid">The <dfn><code>datagrid</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd><span>Interactive content</span>.</dd>
<dd><span>Sectioning root</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd><span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<!- -v2DGS:
<dd><code title="attr-datagrid-multiple">multiple</code></dd>
- ->
<dd><code title="attr-datagrid-disabled">disabled</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLDataGridElement</dfn> : <span>HTMLElement</span> {
<!- -v2DGS:
attribute boolean <span title="dom-datagrid-multiple">multiple</span>;
- -> attribute boolean <span title="dom-datagrid-disabled">disabled</span>;
attribute <span>DataGridListener</span> <span title="dom-datagrid-listener">listener</span>;
<!- - v2DGS:
readonly attribute <span>DataGridSelection</span> <span title="dom-datagrid-selection">selection</span>;
- ->
// columns
void <span title="dom-datagrid-addColumn">addColumn</span>(in <span>Column</span> id, in DOMString label, in DOMString type, in optional HTMLImageElement icon, in optional boolean sortable, in optional boolean hidden);
attribute DOMString <span title="dom-datagrid-sortColumn">sortColumn</span>;
attribute boolean <span title="dom-datagrid-sortAscending">sortAscending</span>;
void <span title="dom-datagrid-clearColumns">clearColumns</span>();
// rows
void <span title="dom-datagrid-renotify">renotify</span>();
void <span title="dom-datagrid-setRowCount">setRowCount</span>(in long childCount, in long rowCount);
void <span title="dom-datagrid-setRows">setRows</span>(in <span>RowList</span> rows);
void <span title="dom-datagrid-insertRows">insertRows</span>(in <span>RowList</span> rows);
void <span title="dom-datagrid-deleteRows">deleteRows</span>(in <span>RowIDList</span> rows);
void <span title="dom-datagrid-repaint">repaint</span>(in <span>RowID</span> row, in DOMString column);
void <span title="dom-datagrid-clearRows">clearRows</span>();
<!- -
v2: opening and closing a row
moving a row's actual ID
- imagine new mail moving a thread up; you just want to add the new mail to the thread and move the thread's first mail to the top
- though actually that should probably just be done using display sorting
- ->
};
typedef DOMString <dfn>Column</dfn>;
typedef sequence<<span>Column</span>> <dfn>ColumnList</dfn>;
typedef sequence<any> <dfn>Cell</dfn>; // <span>Column</span>, any... (exact types expected depend on the column type)
typedef sequence<<span>Cell</span>> <dfn>CellList</dfn>;
typedef sequence<any> <dfn>Row</dfn>; // <span>RowID</span>, long, long, <span>CellList</span>, optional boolean, optional long
typedef sequence<<span>Row</span>> <dfn>RowList</dfn>;
typedef sequence<unsigned long> <dfn>RowID</dfn>;
typedef sequence<<span>RowID</span>> <dfn>RowIDList</dfn>;
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>RenderingContext2DCallback</dfn> {
DOMString <span title="dom-Rendering2DContextCallback-handleEvent">handleEvent</span>(in <span>CanvasRenderingContext2D</span> context, in unsigned long width, in unsigned long height);
};</pre>
</dd>
</dl>
<!- - v2:
* datagrid: cells that are links (<a href=""></a>)
- ->
<p>The <code>datagrid</code> element <span>represents</span> an
interactive representation of tree, list, or tabular data.</p>
<p>The data being presented is provided by script using the methods
described in the following sections.</p>
<!- -v2DGS:
<p>The <dfn
title="attr-datagrid-multiple"><code>multiple</code></dfn> attribute
is a <span>boolean attribute</span>. When set, it indicates that the
user can select more than one row at a time.</p>
- ->
<p>The <dfn
title="attr-datagrid-disabled"><code>disabled</code></dfn> attribute
is a <span>boolean attribute</span> used to disable the
control. <span class="impl">When the attribute is set, the user
agent must disable the <code>datagrid</code>, preventing the user
from interacting with it. The <code>datagrid</code> element should
still continue to update itself when the underlying data changes,
though, as described in the next few sections. However, conformance
requirements stating that <code>datagrid</code> elements must react
to users in particular ways do not apply when the
<code>datagrid</code> is disabled.</span></p>
<div class="impl">
<!- -vsDGS: multiple - ->
<p>The <dfn
title="dom-datagrid-disabled"><code>disabled</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name.</p>
</div>
<!- - v2DGPA: One possible thing to be added is a way to detect when a
row/selection has been deleted, activated, etc, by the user (delete
key, enter key, etc). (v2DGPA = <datagrid> Perform Action) - ->
<h5>Introduction</h5>
<p><i>This section is non-normative.</i></p>
<p>In the <code>datagrid</code> data model, data is structured as a
set of rows representing a tree, each row being split into a number
of columns. The columns are always present in the data model,
although individual columns might be hidden in the presentation.</p>
<hr>
<p>Each row can have child rows. Child rows may be hidden or
shown, by closing or opening (respectively) the parent row.</p>
<p>Rows are referred to by the path along the tree that one would
take to reach the row, using zero-based indices. Thus, the first row
of a list is row "0", the second row is row "1"; the first child row
of the first row is row "0,0", the second child row of the first row
is row "0,1"; the fourth child of the seventh child of the third
child of the tenth row is "9,2,6,3", etc.</p>
<p>The chains of numbers that give a row's path, or identifier, are
represented by arrays of positions, represented in IDL by the
<span>RowID</span> interface.</p>
<p>The root of the tree is represented by an empty array.</p>
<hr>
<p>Each column has a string that is used to identify it in the API,
a label that is shown to users interacting with the column, a type,
and optionally an icon.</p>
<p>The possible types are as follows:</p>
<table>
<thead>
<tr>
<td>Keyword
<td>Description
<tbody>
<tr>
<td><code title="datagrid-type-text">text</code>
<td>Simple text.
<tr>
<td><code title="datagrid-type-editable">editable</code>
<td>Editable text.
<tr>
<td><code title="datagrid-type-checkable">checkable</code>
<td>Text with a check box.
<tr>
<td><code title="datagrid-type-list">list</code>
<td>A list of values that the user can switch between.
<tr>
<td><code title="datagrid-type-progress">progress</code>
<td>A progress bar.
<tr>
<td><code title="datagrid-type-meter">meter</code>
<td>A gauge.
<tr>
<td><code title="datagrid-type-custom">custom</code>
<td>A canvas onto which arbitrary content can be drawn.
</table>
<p>Each column can be flagged as sortable, in which case the user
will be able to sort the view using that column.</p>
<p>Columns are not necessarily visible. A column can be created
invisible by default. The user can select which columns are to be
shown.</p>
<p>When no columns have been added to the <code>datagrid</code>, a
column with no name, whose identifier is the empty string, whose
type is <code title="datagrid-type-text">text</code>, and which is
not sortable, is implied. This column is removed if any explicit
columns are declared.</p>
<p>Each cell uses the type given for its column, so all cells in a
column present the same type of information.</p>
<!- -v2DGS:
<p>Selection of data in a <code>datagrid</code> operates at the row
level. If the <code title="attr-datagrid-multiple">multiple</code>
attribute is present, multiple rows can be selected at once,
otherwise the user can only select one row at a time.</p>
- ->
<!- - v2DGDND: selection should draggable to and from datagrids - ->
<h6>Example: a <code>datagrid</code> backed by a static <code>table</code> element</h6>
...
<h6>Example: a <code>datagrid</code> backed by nested <code>ol</code> elements</h6>
...
<h6>Example: a <code>datagrid</code> backed by a server</h6>
...
<h5>Populating the <code>datagrid</code></h5>
<dl class="domintro">
<dt><var title="">datagrid</var> . <code title="dom-datagrid-listener">listener</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Return the current object that is configured as the
<code>datagrid</code> listener, if any. Returns null if there is
none.</p>
<p>The listener is an object provided by the script author that
receives notifications when the <code>datagrid</code> needs row
data to render itself, when the user opens and closes rows with
children, when the user edits a cell, and when the user invokes a
row's context menu. (The <code>DataGridListener</code> interface
used for this purpose is described in the next section.)</p>
<p>Can be set, to change the current listener.</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-renotify">renotify</code>()</dt>
<dd>
<p>Causes the <code>datagrid</code> to resend notifications to the
listener (if any) for any rows or cells that the
<code>datagrid</code> does not yet have information for.</p>
<!- - useful, e.g., if there is a server error and the script loses
track of what rows it's supposed to be reporting. - ->
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-addColumn">addColumn</code>(<var title="">id</var>, <var title="">label</var>, <var title="">type</var> [, <var title="">icon</var> [, <var title="">sortable</var> [, <var title="">hidden</var> ] ] ] )</dt>
<dd>
<p>Adds a column to the <code>datagrid</code>.</p>
<p>If a column with the given identifier has already been added,
it just replaces the information for that column.</p>
<p>The possible types are enumerated in the previous section.</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-sortColumn">sortColumn</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the identifier of the column by which the data is to be
sorted.</p>
<p>Can be set, to indicate that the sort order has changed. This
will cause the <code>datagrid</code> to clear its position
information for rows, so <code
title="dom-datagrid-setRows">setRows()</code> will have to be
called again with the new sort order.</p>
<p>The columns are not actually sorted by the
<code>datagrid</code>; the data has to be sorted by the script
that adds the rows to the <code>datagrid</code>.</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-sortAscending">sortAscending</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns true if the data is to be sorted with smaller values
first; otherwise, returns false, indicating that bigger values are
to be put first.</p>
<p>Can be set, to indicate that the order is about to change.</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-clearColumns">clearColumns</code>()</dt>
<dd>
<p>Removes all the columns in the <code>datagrid</code>,
reinstating the implied column.</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-setRowCount">setRowCount</code>(<var title="">childCount</var>, <var title="">rowCount</var>)</dt>
<dd>
<p>Sets the numbers of rows in the <code>datagrid</code>,
excluding rows that are descendants of rows that are closed.</p>
<p>Throws a <code>DATAGRID_MODEL_ERR</code> exception if the
arguments contradict each other or previously declared information
(e.g. declaring that the <code>datagrid</code> has three rows when
the 12th row has been declared).</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-setRows">setRows</code>(<var title="">rows</var>)</dt>
<dd>
<p>Updates data for rows in the <code>datagrid</code>, or fills in
data for rows previously implied by a call to <code
title="dom-datagrid-setRowCount">setRowCount()</code> but not
previously declared.</p>
<p>The <var title="">rows</var> argument is an array of rows, each
represented by a further array consisting of:</p>
<ol class="brief">
<li>A <code>RowID</code> object identifying the row.</li>
<li>An integer giving the position of the row in its parent,
given the current sort order, or −1 to set other row data
without setting a position or changing a previously declared
position.</li>
<li>An integer giving the number of children of the row, or 0 if
the row has no children, or −1 if the row has children but
the count is currently unknown. If the number of children has
already been set to 0 or a positive integer, then passing
−1 leaves the previous count unchanged.</li>
<li>An array giving the data for zero or more cells in the row,
as described below.</li>
<li>A boolean declaring whether the row is open or not. This
entry, if omitted, is assumed to be false (closed), unless the
row has already been declared as open.</li>
<li>An integer giving the number of rows that are descendants of
this row, excluding those that are descendants of descendants of
this row that are closed. This entry can be omitted if the row is
closed or if it has already been declared.</li>
</ol>
<p>The array giving the data for the cells in the row consists of
a further set of arrays, one per cell. The first item of each of
these arrays is the column's identifier; the subsequent values
vary based on the type of the column, as follows:</p>
<dl>
<dt><code title="datagrid-type-text">text</code></dt>
<dd>
<ol class="brief">
<li>A string giving the cell's value.
<li>Optionally, an <code>img</code> element giving an icon for the cell.
</ol>
</dd>
<dt><code title="datagrid-type-editable">editable</code></dt>
<dd>
<ol class="brief">
<li>A string giving the cell's value.
<li>Optionally, a <code>datalist</code> element giving a set of predefined options.
<li>Optionally, an <code>img</code> element giving an icon for the cell.
</ol>
</dd>
<dt><code title="datagrid-type-checkable">checkable</code></dt>
<dd>
<ol class="brief">
<li>A string giving the cell's value.
<li>A boolean, indicating whether the cell is checked (true) or not (false).
<li>Optionally, a boolean indicating whether the value of the cell is obscured as indeterminate (true), or not (false).
<li>Optionally, an <code>img</code> element giving an icon for the cell.
</ol>
</dd>
<dt><code title="datagrid-type-list">list</code></dt>
<dd>
<ol class="brief">
<li>A string giving the cell's current value.
<li>A <code>select</code> element giving the <span title="concept-select-option-list">list of options</span>.
<li>Optionally, an <code>img</code> element giving an icon for the cell.
</ol>
</dd>
<dt><code title="datagrid-type-progress">progress</code></dt>
<dd>
<ol class="brief">
<li>A value in the range 0.0 (no progress) to 1.0 (task complete).
</ol>
</dd>
<dt><code title="datagrid-type-meter">meter</code></dt>
<dd>
<ol class="brief">
<li>A number giving the cell's value.
<li>Optionally, a number giving the maximum value, if it's not 1.
<li>Optionally, a number giving the minimum value, if it's not 0.
<li>Optionally, a number giving the highest value that is considered "low".
<li>Optionally, a number giving the lowest value that is considered "high".
<li>Optionally, a number giving the value that is considered optimal.
</ol>
</dd>
<dt><code title="datagrid-type-custom">custom</code></dt>
<dd>
<ol class="brief">
<li>A number giving the minimum width of the cell, in CSS pixels, that is desired.
<li>A number giving the minimum height of the cell, in CSS pixels, that is desired.
<li>A function that is passed a <code>CanvasRenderingContext2D</code> object, along with the width and height (in CSS pixels) of the cell that the context will draw on.
</ol>
</dd>
</dl>
<p>While the rows in a single call to the <code
title="dom-datagrid-setRows">setRows()</code> method can be in any
order, for each row, it is important that all its ancestor rows
and all its open previous siblings are also declared, either in
the same call or in an earlier one.</p>
<p>Throws a <code>DATAGRID_MODEL_ERR</code> exception if the
arguments contradict each other or previously declared information
(e.g. saying that a row's position is 5 when the parent row only
has 3 children, or naming a column that doesn't exist, or
declaring a row without declaring its parent, or changing the
number of children that a row has while that row and its ancestors
are all open).</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-insertRows">insertRows</code>(<var title="">rows</var>)</dt>
<dd>
<p>Inserts the given rows into the <code>datagrid</code>,
increasing the numbers of rows that the <code>datagrid</code>
assumes are present.</p>
<p>The <var title="">rows</var> argument is an array of rows in
the same structure as the argument to the <code
title="dom-datagrid-setRows">setRows()</code> method described
above, with the same expectations of consistency (a given row's
ancestors and earlier open siblings being listed either earlier or
in the same call as a given row). However, unlike with the <code
title="dom-datagrid-setRows">setRows()</code> method, if a row is
inserted along with its child, the child is not included in the
child and row counts of the parent row; every row in the <var
title="">rows</var> argument will increase its parent's counts
automatically.</p>
<p>Throws a <code>DATAGRID_MODEL_ERR</code> exception if the
arguments contradict each other or previously declared
information.</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-deleteRows">deleteRows</code>(<var title="">rows</var>)</dt>
<dd>
<p>Removes the given rows from the <code>datagrid</code>, and
updates the number of rows known to be in the
<code>datagrid</code> accordingly. The argument is an array of
<code>RowID</code> objects identifying the rows to remove.</p>
<p>Throws a <code>DATAGRID_MODEL_ERR</code> exception if the argument
includes a row the <code>datagrid</code> doesn't know about.</p>
<!- - since otherwise behaviour might depend on where the user
scrolled! - ->
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-repaint">repaint</code>(<var title="">row</var>, <var title="">column</var>)</dt>
<dd>
<p>If the given column's type is <code
title="datagrid-type-custom">custom</code>, then causes the
<code>datagrid</code> to reinvoke the function that obtains the
desired rendering.</p>
</dd>
<dt><var title="">datagrid</var> . <code title="dom-datagrid-clearRows">clearRows</code>()</dt>
<dd>
<p>Clears the <code>datagrid</code> of all row data, resetting it
to empty<!- - v2DGS:, and clears the selection- ->.</p>
</dd>
</dl>
<div class="impl">
<h6>The listener</h6>
<p>The <dfn
title="dom-datagrid-listener"><code>listener</code></dfn> IDL
attribute allows authors to specify an object that will receive all
the notifications from the <code>datagrid</code>. Initially, its
value must be null. On getting, it must return its value. On
setting, its value must be set to the new value, and then the user
agent must <span>queue a task</span> to call the <code
title="dom-listener-initialize">initialize()</code> method with the
<code>datagrid</code> element as its only argument.</p>
<h6>The columns</h6>
<p>The columns are represented by the <dfn>column list</dfn>, an
ordered list of entries for columns, each of which consists of:</p>
<dl>
<dt>An identifier</dt>
<dd>A string used to identify the column in the API.</dd>
<dt>A label</dt>
<dd>A string used in the user interface.</dd>
<dt>A type</dt>
<dd>One of the types described below.</dd>
<dt>An icon</dt>
<dd>An image, copied from an <code>img</code> element when the
column was declared.</dd>
<dt>Whether the column is sortable</dt>
<dd>A boolean indicating whether the user can request that the data
be sorted by this column (true), or not (false).</dd>
<dt>Whether the column is visible</dt>
<dd>A boolean indicating whether the column is part of the
<code>datagrid</code>'s rendering.</dd>
</dl>
<p>Initially, the <span>column list</span> must have a single
column, the <dfn>default column</dfn>, whose identifier is the empty
string, whose label is the empty string, whose type is <code
title="datagrid-type-text">text</code>, with no icon, which is not
sortable, and which <em>is</em> visible.</p>
<hr>
<p>The <dfn title="dom-datagrid-addColumn"><code>addColumn(<var
title="">id</var>, <var title="">label</var>, <var
title="">type</var>, <var title="">icon</var>, <var
title="">sortable</var>, <var title="">hidden</var>)</code></dfn>
method must run the following steps:</p>
<ol>
<li><p>If there is already an entry in <span>column list</span>,
other than the <span>default column</span>, whose identifier is
<var title="">id</var>, throw a <code>DATAGRID_MODEL_ERR</code>
exception and abort these steps.</p></li>
<li>
<p>If <var title="">type</var> is not a string equal to one of the
<span>allowed <code>datagrid</code> column types</span>, then
throw a <code>DATAGRID_MODEL_ERR</code> exception and abort these
steps.</p>
</li>
<li><p>If the <var title="">icon</var> argument is present and not
null, but the given <code>img</code> element's <code
title="dom-img-complete">complete</code> attribute is false, then
let <var title="">icon</var> be null.</p></li>
<li><p>If the <var title="">icon</var> argument is present and not
null, then copy the image data from that <code>img</code> element,
and let <var title="">image</var> be the copy of that image
data. Otherwise, let <var title="">image</var> be nothing.</p></li>
<li><p>Append a new entry to the <span>column list</span>, with
<var title="">id</var> as its identifier, <var title="">label</var>
as its label, <var title="">type</var> as its type, and <var
title="">image</var> as its icon. Let the column be sortable if the
<var title="">sortable</var> argument is present and true, and make
it visible unless the <var title="">hidden</var> argument is
present and true.</p></li>
<li><p>If the <span>column list</span> contains the <span>default
column</span>, then remove the <span>default column</span> from the
<span>column list</span>, discard any data for cells in that column
in any rows in the <code>datagrid</code>, set <code
title="dom-datagrid-sortColumn">sortColumn</code> to <var
title="">id</var>, set <code
title="dom-datagrid-sortAscending">sortAscending</code> to true,
and run the <span><code>datagrid</code> resort
steps</span>.</p></li>
</ol>
<hr>
<p>The <dfn
title="dom-datagrid-sortColumn"><code>sortColumn</code></dfn> IDL
attribute gives the current column used for sorting. Initially, its
value must be the empty string. On getting, it must return its
current value. On setting, if the new value doesn't match the
identifier of one of the columns in the <span>column list</span>,
then the user agent must throw a <code>DATAGRID_MODEL_ERR</code>
exception. Otherwise, if the new value is not the same as its
current value, then the user agent must set the attribute to the new
value, and then run the <span><code>datagrid</code> resort
steps</span>.</p>
<p>The <dfn
title="dom-datagrid-sortAscending"><code>sortAscending</code></dfn>
IDL attribute specifies the direction that the tree is sorted in,
ascending (true) or descending (false). Initially, its value must be
true (ascending). On getting, it must return its current value. On
setting, if the new value is not the same as its current value, then
the user agent must set the attribute to the new value, and then run
the <span><code>datagrid</code> resort steps</span>.</p>
<p>When a column is marked as being sortable, the user agent should
allow the user to select that column to be the column used for
sorting, and should allow the user to chose whether the sort order
is ascending or descending.</p>
<p>When the user changes the sort order in this manner, the user
agent must update the <code
title="dom-datagrid-sortColumn">sortColumn</code> and <code
title="dom-datagrid-sortAscending">sortAscending</code> attributes
appropriately, and then run the <span><code>datagrid</code> resort
steps</span>.</p>
<p class="note">The <span><code>datagrid</code> resort steps</span>
are described in the next section.</p>
<hr>
<p>The <dfn
title="dom-datagrid-clearColumns"><code>clearColumns()</code></dfn>
method, if the <span>column list</span> doesn't contain the
<span>default column</span>, must empty the <span>column
list</span>, append the <span>default column</span> to the now empty
<span>column list</span>, discard any data for cells in all rows in
the <code>datagrid</code>, set <code
title="dom-datagrid-sortColumn">sortColumn</code> to the empty
string, set <code
title="dom-datagrid-sortAscending">sortAscending</code> to true, and
run the <span><code>datagrid</code> resort steps</span>. (If the
<span>column list</span> is already just the <span>default
column</span>, then the method does nothing.)</p>
<h6>The rows</h6>
<p>A <code>datagrid</code> element is intended to show a
representation of a tree, where typically the user only sees a
small part of the tree at a time.</p>
<p>To make this efficient, the <code>datagrid</code> element
<em>actually</em> shows a small part of a <em>sparse</em> tree, so
that only relevant parts of the data structure need be loaded at any
time. Specifically, the model requires only that all the ancestor
rows of the displayed rows be loaded, as well as any open earlier
siblings (in the displayed sort order) of the displayed rows.</p>
<p>Conceptually, therefore, a <code>datagrid</code> has a number of
related sparse data structures backing it.</p>
<p>The first is the <dfn>natural order sparse data tree</dfn>. This
is the structure in which rows are entered as they are declared, in
their natural order. This can differ from the order actually
displayed to the user. It consists of nested sparse lists of
rows. In the <span>natural order sparse data tree</span>, a row will
always have all its parents already declared. Once a row is added to
this structure, it can only be removed by the <code
title="dom-datagrid-deleteRows">deleteRows()</code> and <code
title="dom-datagrid-clearRows">clearRows()</code> methods. The order of
nodes in this tree never changes; to move a node in this tree, it
has to be removed and then another row (with the same data)
reinserted elsewhere.</p>
<p>The second structure is the <dfn>display order sparse data
tree</dfn>. This is a similar structure that contains a subset of
the rows in the <span>natural order sparse data tree</span>, ordered
in the order given by the <code
title="dom-datagrid-sortAscending">sortAscending</code> and <code
title="dom-datagrid-sortColumn">sortColumn</code> attributes, and
excluding rows with one or more ancestors that are closed. This tree
is cleared whenever the <code
title="dom-datagrid-sortAscending">sortAscending</code> and <code
title="dom-datagrid-sortColumn">sortColumn</code> attributes
change.</p>
<p>The third structure is the <dfn>display order sparse data
list</dfn>. This structure is a flattened representation of the
<span>display order sparse data tree</span>.</p>
<p>At any time, a number of consecutive rows in the <span>display
order sparse data list</span> are physically visible to the
user. The <code>datagrid</code> fires notifications to a <span
title="dom-datagrid-listener">listener</span> (provided by script),
and the listener, or other some script, is expected to feed the
<code>datagrid</code> with the information needed to render the
control.</p>
<p>A <code>datagrid</code> has a <dfn>pending <code>datagrid</code>
rows list</dfn>, which is a list of rows in the <span>display order
sparse data list</span> for which the <code>datagrid</code> has sent
notifications requesting information but not yet received
information about.</p>
<p>A <code>datagrid</code> also has a <dfn>pending
<code>datagrid</code> <em>cells</em> list</dfn>, which is a list of
row/column pairs (cells) for which the <code>datagrid</code> has
sent notifications requesting information but not yet received
information about.</p>
<p>User agents may discard information about rows that are not
displayed and that are not ancestors or open earlier siblings of
rows or ancestors of rows that are displayed.</p>
<hr>
<p>These structures are different views of the collection of rows
that form the <code>datagrid</code>. Each row has the following
information associated with it:</p>
<dl>
<dt>A parent</dt>
<dd><p>Either another row, or the <code>datagrid</code> itself. This
is the parent of the row in the <span>natural order sparse data
tree</span> and the <span>display order sparse data tree</span>
for the <code>datagrid</code>.</p></dd>
<dt>A natural order position relative to the other rows with the
same parent</dt>
<dd>
<p>This is the number of rows that precede this row under the same
parent in the <span>natural order sparse data tree</span>. This
number can't be changed relative to other rows in the same parent;
to change the relative natural order of data in the
<code>datagrid</code>, the original rows have to be removed and
new rows (with the same data but different natural positions)
inserted in their place. (The exact number of a row can change, as
new rows can be inserted above it.)</p>
<p>A row can be identified by a <code>RowID</code> object. This is
an array of numbers, consisting of the natural order positions of
each ancestor row and the row itself, starting from the furthest
ancestor. Thus, for instance, the fourth child row of the first
child row of the second row in a <code>datagrid</code> would be
identified by a <code>RowID</code> object whose value is <code
title="">[1, 0, 3]</code>. A row's identifier changes if rows are
<span title="dom-datagrid-insertRows">inserted before it</span> in
the <code>datagrid</code>.</p>
</dd>
<dt>A display order position relative to the other rows with
the same parent</dt>
<dd><p>This is the number of rows that precede this row under the
same parent in the <span>display order sparse data
tree</span>. This number can be unknown. If the sort order
changes, then this information is lost (as the <span>display order
sparse data tree</span> is cleared).</p></dd>
<dt>A child count</dt>
<dd><p>The number of rows that have this row as a parent. If this is
zero, the row cannot be opened. If this is −1, then the
child count is unknown but the row can be opened. This value can be
changed by the <code title="dom-datagrid-setRows">setRows()</code>
method only if the current value is −1 or if the row or one
of its ancestors is closed. Otherwise, it can only be changed
indirectly using the <code
title="dom-datagrid-insertRows">insertRows()</code> and <code
title="dom-datagrid-deleteRows">deleteRows()</code> methods.</p></dd>
<dt>An open flag</dt>
<dd><p>A boolean indicating whether the row is open (true) or
closed (false). Once set, the flag can only be changed by the user
or while one of the row's ancestors is itself closed. A row can
also be in a third state, "opening", which is treated as closed for
all purposes except that the user agent may indicate that the row
is in this special state, and except that when the row is updated
to have a row count, the row will switch to being open.</p></dd>
<dt>A row count</dt>
<dd><p>The number of rows that have this row as a parent or
ancestor, and that do not have an ancestor that is a descendant of
this row that is itself closed. If this is −1, then the row
count is unknown. This value can be changed by the <code
title="dom-datagrid-setRows">setRows()</code> method only if the
row or one of its ancestors is closed (or opening, but not
open). Otherwise, it can only be changed indirectly using the <code
title="dom-datagrid-insertRows">insertRows()</code> and <code
title="dom-datagrid-deleteRows">deleteRows()</code>
methods.</p></dd>
<dt>Cells</dt>
<dd><p>The data that applies to this row. Cell data is discussed in
more detail below.</p></dd>
</dl>
<p>The <code>datagrid</code> itself also has a <dfn title="datagrid
child count">child count</dfn> and a <dfn title="datagrid row
count">row count</dfn>, which are analogous to the child counts and
row counts for rows. Initially, these must be zero.</p>
<hr>
<p>The <dfn><code>datagrid</code> resort steps</dfn>, which are
invoked when the sort order changes as described in the previous
section, are as follows:</p>
<ol>
<li>
<p>Clear the <span>display order sparse data tree</span>
(i.e. mark the display order position of all the rows in the
<code>datagrid</code> as unknown).</p>
<p>User agents may cache the position information of rows for
various values of <code
title="dom-datagrid-sortColumn">sortColumn</code> and <code
title="dom-datagrid-sortAscending">sortAscending</code>, instead
of discarding the information altogether. If the user agent caches
this information, and has information that applies to the current
values of <code title="dom-datagrid-sortColumn">sortColumn</code>
and <code title="dom-datagrid-sortAscending">sortAscending</code>,
then the user agent may repopulate the <span>display order sparse
data tree</span> from this information.</p>
</li>
<li>
<p>Clear the <span>pending <code>datagrid</code> rows list</span>
and the <span>pending <code>datagrid</code> cells list</span>.</p>
</li>
<li>
<p>Invoke the <span><code>datagrid</code> update display
algorithm</span>.</p>
</li>
<!- - v2: queue a task to fire an event, or tell the listener the
sort order changed, or something - ->
</ol>
<hr>
<p>The <dfn
title="dom-datagrid-renotify"><code>renotify()</code></dfn> method
must empty the <span>pending <code>datagrid</code> rows list</span>
and the <span>pending <code>datagrid</code> cells list</span>, and
invoke the <span><code>datagrid</code> update display
algorithm</span>.</p>
<hr>
<p>The <dfn title="dom-datagrid-setRowCount"><code>setRowCount(<var
title="">childCount</var>, <var
title="">rowCount</var>)</code></dfn> method must run the following
steps:</p>
<ol>
<li>
<p>Set the <span><code>datagrid</code> child count</span> to <var
title="">childCount</var>, the <span><code>datagrid</code> row
count</span> to <var title="">rowCount</var>.</p>
</li>
<li>
<p><span>Audit the <code>datagrid</code></span>. If this fails,
then revert the changes made in the previous step, throw a
<code>DATAGRID_MODEL_ERR</code> exception, and abort these
steps.</p>
</li>
<li>
<p>Invoke the <span><code>datagrid</code> update display
algorithm</span>.</p>
</li>
</ol>
<hr>
<p>The <dfn title="dom-datagrid-setRows"><code>setRows(<var
title="">rows</var>)</code></dfn> method must run the following
steps:</p>
<ol>
<li>
<p><span title="type-check a RowList object">Type-check the <var
title="">rows</var> argument</span>. If this fails, throw a
<code>TypeError</code> exception, and abort these steps.</p>
</li>
<li>
<p><span title="partially sort a RowList object">Partially sort
the <var title="">rows</var> argument</span>.</p>
</li>
<li>
<p>For each <code>Row</code> object in the <var
title="">rows</var> argument, in order, perform the appropriate
steps from the list below.</p>
<p class="note">The changes made to the <code>datagrid</code>'s
data structures in this step get reverted (as required below) if
any consistency errors are detected either in this step or the
next.</p>
<dl>
<dt>If there already exists a row in the <code>datagrid</code>'s
<span>natural order sparse data tree</span> with the same
identifier as given by the <code>Row</code> object's
<code>RowID</code> object, and that row and all its ancestors are
open</dt>
<dd>
<p>If one of the following conditions is true, then revert all
the changes done in this step, throw a
<code>DATAGRID_MODEL_ERR</code> exception, and abort these
steps:</p>
<ul>
<li>The value of the <code>Row</code> object's second entry is
neither −1 nor equal to the child count of the
preexisting row.</li>
<li>The <code>Row</code> object has fewer than four
entries or more than six entries.</li>
<li>The <code>Row</code> object has five or more entries, and
its fifth entry is false.</li>
<li>The <code>Row</code> object has six entries, and its sixth
entry is not equal to the row count of the preexisting
row.</li>
</ul>
</dd>
<dt>If there already exists a row in the <code>datagrid</code>'s
<span>natural order sparse data tree</span> with the same
identifier as given by the <code>Row</code> object's
<code>RowID</code> object, but either that row or one of its
ancestors is closed</dt>
<dd>
<p>Set the preexisting row's child count to the value of the
<code>Row</code> object's second entry.</p>
<p>If the <code>Row</code> object has five or more entries, and
either its fifth entry is true and the preexisting row is closed
but not opening, or its fifth entry is false and the preexisting
row is open, then: if the preexisting row has no ancestor row
that is closed, then revert all the changes done in this step,
throw a <code>DATAGRID_MODEL_ERR</code> exception, and abort
these steps; otherwise, if the fifth entry is false, then close
the row; otherwise, open the row.</p>
<p>If the <code>Row</code> object has six entries, set the
preexisting row's row count to the value of the <code>Row</code>
object's sixth entry.</p>
<p>If the preexisting row is opening, then: increase the
<span><code>datagrid</code> row count</span> and the row counts
of any ancestor rows by the number of rows that the preexisting
row now has in its row count, then open the row.</p> <!- - we
should also "update the <span>pending <code>datagrid</code> rows
list</span> and the <span>pending <code>datagrid</code> cells
list</span> accordingly" - ->
</dd>
<dt>There does not exist a row in the <code>datagrid</code>'s
<span>natural order sparse data tree</span> with the same
identifier as given by the <code>Row</code> object's
<code>RowID</code> object</dt>
<dd>
<p>If the <code>RowID</code> object has a length greater than 1,
then verify that there is a row identified by the
<code>RowID</code> consisting of all but the last number in the
<code>Row</code> object's <code>RowID</code>. If there is no
such row present in the <span>natural order sparse data
tree</span>, then revert all the changes done in this step,
throw a <code>DATAGRID_MODEL_ERR</code> exception, and abort
these steps.</p>
<p>Create a row and insert it into the <span>natural order
sparse data tree</span>, such that its parent is the row
identified by the <code>RowID</code> consisting of all but the
last number in the <code>Row</code> object's <code>RowID</code>,
or the <code>datagrid</code> if the length of the
<code>Row</code> object's <code>RowID</code> is 1; with its
natural order position being the last number of the
<code>Row</code> object's <code>RowID</code>; with the child
count being the value of the third entry of the <code>Row</code>
object; with the row being marked closed unless the
<code>Row</code> object has five or more entries and its fifth
entry is true, in which case the row is open; and with its row
count being −1 unless the <code>Row</code> object has six
entries, in which case the row count is equal to the value of
the <code>Row</code> object's sixth entry.</p>
</dd>
</dl>
</li>
<li>
<p><span>Audit the <code>datagrid</code></span>. If this fails,
then revert the changes made in the previous step, throw a
<code>DATAGRID_MODEL_ERR</code> exception, and abort these
steps.</p>
</li>
<li>
<p>For each <code>Row</code> object in the <var
title="">rows</var> argument, in order, <span title="apply a Row
object">apply the <code>Row</code> object</span>.</p>
</li>
<li>
<p>Invoke the <span><code>datagrid</code> update display
algorithm</span>.</p>
</li>
</ol>
<hr>
<p>The <dfn title="dom-datagrid-insertRows"><code>insertRows(<var
title="">rows</var>)</code></dfn> method must run the following
steps:</p>
<ol>
<li>
<p><span title="type-check a RowList object">Type-check the <var
title="">rows</var> argument</span>. If this fails, throw a
<code>TypeError</code> exception, and abort these steps.</p>
</li>
<li>
<p><span title="partially sort a RowList object">Partially sort
the <var title="">rows</var> argument</span>.</p>
</li>
<li>
<p>For each <code>Row</code> object in the <var
title="">rows</var> argument, in order, run the following
steps:</p>
<p class="note">The changes made to the <code>datagrid</code>'s
data structures in this step get reverted (as required below) if
any consistency errors are detected either in this step or the
next.</p>
<ol>
<li>
<p>Let <var title="">parent</var> be the row identified by the
<code>RowID</code> consisting of all but the last number in the
<code>Row</code> object's <code>RowID</code>, or the
<code>datagrid</code> itself if the <code>Row</code> object's
<code>RowID</code> has length 0.</p>
<p>If there is no such row present in the <span>natural order
sparse data tree</span>, then revert all the changes done in
this algorithm, throw a <code>DATAGRID_MODEL_ERR</code>
exception, and abort these steps.</p>
</li>
<li>
<p>Increment by one the natural order position of all rows whose
parent is <var title="">parent</var> and whose natural order
position is equal to or greater than the last number of the
<code>Row</code> object's <code>RowID</code>.</p>
</li>
<li>
<p>If the value of the <code>Row</code> object's second entry is
not −1, then increment by one the display order position
of all rows whose parent is <var title="">parent</var> and whose
display order position is equal to or greater than the value of
the <code>Row</code> object's second entry.</p>
<!- -(Not sure how to really say this.)
<p>Update the <span>pending <code>datagrid</code> rows
list</span> and the <span>pending <code>datagrid</code> cells
list</span> accordingly.</p>
- ->
</li>
<li>
<p>Create a row and insert it into the <span>natural order
sparse data tree</span>, such that its parent is <var
title="">parent</var>; with its natural order position being the
last number of the <code>Row</code> object's <code>RowID</code>;
with the child count being the value of the third entry of the
<code>Row</code> object; with the row being marked closed unless
the <code>Row</code> object has five or more entries and its
fifth entry is true, in which case the row is open; and with its
row count being −1 unless the <code>Row</code> object has
six entries, in which case the row count is equal to the value
of the <code>Row</code> object's sixth entry.</p>
</li>
</ol>
</li>
<li>
<p>For each <code>Row</code> object in the <var
title="">rows</var> argument, in order, <span title="apply a Row
object">apply the <code>Row</code> object</span>.</p>
</li>
<li>
<p>Invoke the <span><code>datagrid</code> update display
algorithm</span>.</p>
</li>
</ol>
<hr>
<p>When an algorithm requires the user agent to <dfn>type-check a
<code>RowList</code> object</dfn> (an array), each entry in the
object must be checked against the following requirements. If any
are false, then the type-check fails, otherwise it passes.</p>
<ul>
<li><p>The entry is a <code>Row</code> object (an
array).</p></li>
<li><p>The first value in the <code>Row</code> is a
<code>RowID</code> object (also an array), whose length is at least
1, and whose values are all integers greater than or equal to
zero.</p></li>
<li><p>The numbers in the <code>RowID</code> object do not exactly
match any of the other entries in the <code>RowList</code> object
(i.e. no two <code>Row</code> objects have the same
identifier).</p></li>
<li><p>The second value in the <code>Row</code> is an integer that
is either −1, zero, or a positive integer.</p></li>
<li><p>The third value in the <code>Row</code> is an integer that
is either −1, zero, or a positive integer.</p></li>
<li><p>The fourth value in the <code>Row</code> is a
<code>CellList</code> object (yet another array).</p></li>
<li><p>Each entry in the <span>CellList</span> object is a
<code>Cell</code> object (again, an array).</p></li>
<li><p>Each <code>Cell</code> object in the <span>CellList</span>
object has as its first value a <code>Column</code> object (a
string), and its value is the identifier of one of the columns in
the <span>column list</span>.</p></li>
<li>
<p>Each <code>Cell</code> object in the <span>CellList</span>
object has as its second and subsequent entries values that match
the following requirements, as determined by the type of the
column identified by the first entry:</p>
<dl>
<dt>If the column's type is <code title="datagrid-type-text">text</code></dt>
<dd>
<p>The second entry's value is a string, and either there are
only two entries, or there are three, and the third entry is
an <code>img</code> element.</p>
<p>If there is an <code>img</code> element specified, its <code
title="dom-img-complete">complete</code> attribute is true.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-editable">editable</code></dt>
<dd>
<p>The second entry's value is a string, and either there are
only two entries, or the third entry is a
<code>datalist</code> element, and either there are only three
entries, or there are four, and the fourth entry is an
<code>img</code> element.</p>
<p>If there is an <code>img</code> element specified, its <code
title="dom-img-complete">complete</code> attribute is true.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-checkable">checkable</code></dt>
<dd>
<p>The second entry's value is a string, the third entry is a
boolean, and either there are only three entries, or the
fourth entry is also a boolean, and either there are only four
entries, or there are five, and the fifth entry is an
<code>img</code> element.</p>
<p>If there is an <code>img</code> element specified, its <code
title="dom-img-complete">complete</code> attribute is true.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-list">list</code></dt>
<dd>
<p>The second entry's value is a string, the third entry is a
<code>select</code> element, and either there are only three
entries, or there are four, and the fourth entry is an
<code>img</code> element.</p>
<p>If there is an <code>img</code> element specified, its <code
title="dom-img-complete">complete</code> attribute is true.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-progress">progress</code></dt>
<dd>
<p>There are only two entries, the second entry's value is a
number, and the number's value is between 0.0 and 1.0
inclusive.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-meter">meter</code></dt>
<dd>
<p>There are at least two, but possibly up to seven, entries,
all entries but the first one are numbers, and the following
relationships hold:</p>
<ul class="brief">
<li>The second entry is less than the third, or less than 1.0
if the third is absent.</li>
<li>The second entry is greater than the fourth, or greater
than 0.0 if the fourth is absent.</li>
<li>If there are at least three entries, the third entry is
greater than the fourth, or greater than zero if the fourth
is absent.</li>
<li>If there are at least five entries, the fifth is not
greater than the third and not less than the fourth.</li>
<li>If there are at least six entries, the sixth is not
greater than the third and not less than the fifth.</li>
<li>If there are at least seven entries, the fifth is not
greater than the third and not less than the fourth.</li>
</ul>
</dd>
<dt>If the column's type is <code title="datagrid-type-custom">custom</code></dt>
<dd>
<p>There are four entries, the second and third are numbers
that are integers greater than zero, and the fourth is a
<code>Rendering2DContextCallback</code> object (a
function).</p>
</dd>
</dl>
</li>
<li><p>Either there are only four values in the <code>Row</code>,
or the fifth value in the <code>Row</code> is a boolean.</p></li>
<li><p>Either there are only four or five values in the
<code>Row</code>, or there are six, and the sixth value in the
<code>Row</code> an integer that is greater than or equal to
zero.</p></li>
</ul>
<p>Where the above requirements say that a value is to be a string,
the user agent must apply the ToString() conversion operator to the
value, assume that the value was indeed a string, and use the result
in the rest of the algorithm as if it had that had been the value
passed to the method. <a href="#refsECMA262">[ECMA262]</a></p>
<p>Where the above requirements say that a value is to be a number,
the user agent must first apply the ToNumber() conversion operator
to the value, and then verify that the result is neither an Infinity
value nor a Not-a-Number (NaN) value. If this result is indeed
acceptable (i.e. finite), the user agent must use the result in the
rest of the algorithm as if it had that had been the value passed to
the method. <a href="#refsECMA262">[ECMA262]</a></p>
<p>Where the above requirements say that a value is to be an
integer, the user agent must first apply the ToNumber() conversion
operator to the value, and then verify that the result is a finite
integer. If so, the user agent must use the result in the rest of
the algorithm as if it had that had been the value passed to the
method. <a href="#refsECMA262">[ECMA262]</a></p>
<p>Where the above requirements say that a value is to be a boolean,
the user agent must apply the ToBoolean() conversion operator to the
value, assume that the value was indeed a boolean, and use the
result in the rest of the algorithm as if it had that had been the
value passed to the method. <a href="#refsECMA262">[ECMA262]</a></p>
<hr>
<p>When an algorithm requires the user agent to <dfn>audit the
<code>datagrid</code></dfn>, the <code>datagrid</code> must be
checked against the following requirements. If any are false, then
the audit fails, otherwise it passes.</p>
<ul>
<li>There is no row whose natural order position is greater than or
equal to the child count of its parent row in the <span>natural
order sparse data tree</span>.</li>
<li>There is no row whose display order position is greater than or
equal to the child count of its parent row in the <span>display
order sparse data tree</span>.</li>
<li>There is no row such that the sum of that row's child count and
the row counts all the open rows that are direct children of that
row in the <span>natural order sparse data tree</span> is less than
that row's row count.</li>
<li>Of the rows whose child count is equal to the number of rows
that are direct children of that row in the <span>natural order
sparse data tree</span>, there is none such that the sum of that
row's child count and the row counts of all the open rows that are
direct children of that row in the <span>natural order sparse data
tree</span> is greater than that row's row count.</li>
</ul>
<p>For the purposes of this audit, the <code>datagrid</code> must be
treated as the parent row of all the rows that are direct children
of the <code>datagrid</code> in the <span>natural order sparse data
tree</span> and the <span>display order sparse data tree</span>. The
child count of this implied row is the <span><code>datagrid</code>
child count</span>, and the row count of this implied row is the
<span><code>datagrid</code> row count</span>.</p>
<hr>
<p>When an algorithm requires the user agent to <dfn>partially sort
a <code>RowList</code> object</dfn> (an array), the entries in the
object must be resorted such that <code>Row</code> objects are
listed after any of their ancestors and after any of their earlier
siblings. In other words, for any two <code>Row</code> objects <var
title="">a</var> and <var title="">b</var> in the
<code>RowList</code>, where <var title="">a</var> is before <var
title="">b</var> after the sort, the following conditions must
hold:</p>
<ul>
<li><p>If their <code>RowID</code> objects are the same length and
have values that are equal except for the last value, then the last
value of <var title="">a</var>'s <code>RowID</code>'s last value
must be less than <var title="">b</var>'s <code>RowID</code>'s last
value (i.e. earlier siblings must come before their later
siblings).</p></li>
<li><p>If their <code>RowID</code> objects are not the same length,
but the values in the shorter of the two are the same as the first
few values in the longer one, then <var title="">a</var>'s
<code>RowID</code> must be the shorter one (i.e. ancestors must
come before their descendants).</p></li>
</ul>
<hr>
<p>The <dfn title="dom-datagrid-deleteRows"><code>deleteRows(<var
title="">rows</var>)</code></dfn> method must run the following
steps:</p>
<ol>
<li>
<p>If any of the entries in <var title="">rows</var> are not
<code>RowID</code> objects consisting of one or more entries whose
values are all integers that are greater than or equal to zero,
then throw a <code>TypeError</code> exception and abort these
steps.</p>
<p>To check if a value is an integer, the user agent must first
apply the ToNumber() conversion operator to the value, and then
verify that the result is a finite integer. If so, the user agent
must use the result in the rest of the algorithm as if it had that
had been the value passed to the method. <a
href="#refsECMA262">[ECMA262]</a></p>
</li>
<li>
<p>If any of the <code>RowID</code> objects in the <var
title="">rows</var> argument identify a row that isn't present in
the <span>natural order sparse data tree</span>, then throw a
<code>DATAGRID_MODEL_ERR</code> exception and abort these
steps.</p>
</li>
<li>
<p>If any row is listed twice in the <var title="">rows</var>
argument, then throw a <code>DATAGRID_MODEL_ERR</code> exception
and abort these steps.</p>
</li>
<li>
<p>Sort the <var title="">rows</var> argument such that the
entries are given in the same order as the rows they identify
would be visited in a pre-order, depth first traversal of the
<span>natural order sparse data tree</span>.</p>
</li>
<li>
<p>For each row identified by entries in <var title="">rows</var>,
<em>in reverse order</em>, run the following steps:</p>
<ol>
<li>
<p>Decrement the child count of the row's parent row, if that
child count is greater than zero. If the row has no parent,
decrement the <span><code>datagrid</code> child
count</span>.</p>
<p>If the row has a parent row, and its child count is now zero,
then close that row.</p>
</li>
<li>
<p>Let <var title="">delta</var> be one more than the row's row
count if the row is open and its row count is greater than zero;
otherwise, let <var title="">delta</var> be one.</p>
</li>
<li>
<p>Let <var title="">ancestor</var> be the row.</p>
</li>
<li>
<p><i>Row count loop</i>: Let <var title="">ancestor</var> be
<var title="">ancestor</var>'s parent row, if any, or null if it
has none.</p>
</li>
<li>
<p>If <var title="">ancestor</var> is null, then decrement the
<span><code>datagrid</code> row count</span> by <var
title="">delta</var>. Otherwise, if <var title="">ancestor</var>
is open, then decrement its row count by <var
title="">delta</var>.</p>
</li>
<li>
<p>If <var title="">ancestor</var> is not null, then jump back
to the step labeled <i>row count loop</i> above.</p>
</li>
<li>
<p>Let <var title="">parent</var> be the row's parent, or the
<code>datagrid</code> if the row has no parent.</p>
</li>
<li>
<p>Decrement by one the natural order position of all rows whose
parent is <var title="">parent</var> and whose natural order
position is equal to or greater than the row's own natural order
position.</p>
</li>
<li>
<p>If the row is in the <span>display order sparse data
tree</span>, then decrement by one the display order position of
all rows whose parent is <var title="">parent</var> and whose
display order position is equal to or greater than the row's own
display order position.</p>
</li>
<li>
<p>Clear the row and its descendants from the
<code>Datagrid</code>.</p>
</li>
</ol>
</li>
<li>
<p>Invoke the <span><code>datagrid</code> update display
algorithm</span>.</p>
</li>
</ol>
<hr>
<p>The <dfn
title="dom-datagrid-clearRows"><code>clearRows()</code></dfn> method
must empty the <span>natural order sparse data tree</span>, reset
both the <span><code>datagrid</code> child count</span> and the
<span><code>datagrid</code> row count</span> to zero, and invoke the
<span><code>datagrid</code> update display algorithm</span>.</p>
<hr>
<p>The <dfn title="dom-datagrid-repaint"><code>repaint(<var
title="">row</var>, <var title="">column</var>)</code></dfn> method
must cause the user agent to clear its cache for the cell specified
by the identifier <var title="">row</var> and the column <var
title="">column</var>, if that column's type is <code
title="datagrid-type-custom">custom</code>. If the given column has
not been declared, or its type is not <code
title="datagrid-type-custom">custom</code>, then the user agent must
throw a <code>DATAGRID_MODEL_ERR</code> exception. If the given row
is not known, then the method must do nothing. If the cell is indeed
cleared, the user agent must reinvoke the previously registered
<code>RenderingContext2DCallback</code> callback when it needs to
repaint that row.</p>
<hr>
<p>If a row has a child count that isn't zero, then the user agent
should offer to the user the option of opening and closing the
row.</p>
<p>When a row is opened, if the row's row count is greater than
zero, then the user agent must increase the
<span><code>datagrid</code> row count</span> and the row counts of
any ancestor rows by the number of rows that the newly opened row
has in its row count<!- - we should also "update the <span>pending
<code>datagrid</code> rows list</span> and the <span>pending
<code>datagrid</code> cells list</span> accordingly" - ->, then must
mark the row as open, then may fill in the <span>display order
sparse data tree</span> with any information that the user agent has
cached about the display order positions of descendants of the newly
opened row, and then must invoke the <code
title="dom-listener-rowOpened">rowOpened()</code> method on the
current <code title="dom-datagrid-listener">listener</code> with as
its first argument a <code>RowID</code> object identifying the row
that was opened and as its second argument the boolean false, and
then must invoke the <span><code>datagrid</code> update display
algorithm</span>.</p>
<p>On the other hand, when a row is opened and the row's row count
is −1, then the user agent must mark the row as opening, and
then must invoke the <code
title="dom-listener-rowOpened">rowOpened()</code> method on the
current <code title="dom-datagrid-listener">listener</code> with as
its first argument a <code>RowID</code> object identifying the row
that was opened and as its second argument the boolean true.</p>
<p>When a row is closed, the user agent must decrease the
<span><code>datagrid</code> row count</span> and the row counts of
any ancestor rows by the number of rows that the newly closed row
has in its row count, and then must invoke the <code
title="dom-listener-rowOpened">rowOpened()</code> method on the
current <code title="dom-datagrid-listener">listener</code> with as
its first and only argument a <code>RowID</code> object identifying
the row that was opened.</p>
<h6>The cells</h6>
<p>Each row has one cell per column. Each cell has the same type as
its column. The <dfn>allowed <code>datagrid</code> column
types</dfn>, what they represent, and the requirements for when the
user interacts with them, are as follows:</p>
<dl>
<dt><dfn title="datagrid-type-text"><code>text</code></dfn></dt>
<dd>
<p>The cell represents some text and an optional image.</p>
</dd>
<dt><dfn title="datagrid-type-editable"><code>editable</code></dfn></dt>
<dd>
<p>The cells represents some editable text, an optional
<code>datalist</code> giving autocompletion hints, and an
optional image.</p>
<p>If there is a <code>datalist</code> element, the user agent
should offer the suggestions represented by that element to the
user. The user agent may use the suggestion's <span
title="concept-option-label">label</span> to identify the
suggestion. If the user selects a suggestion, then the editable
text must be set to the selected suggestion's <span
title="concept-option-value">value</span>, as if the user had
written that value himself.</p>
<p>When the user edits the value, either directly or using the
<code>datalist</code>, the user agent must invoke the <code
title="dom-listener-cellChanged">cellChanged()</code> method on
the current <code title="dom-datagrid-listener">listener</code>
with as its first argument a <code>RowID</code> identifying the
cell's row, as its second argument the identifier of the cell's
column, as its third argument the new value, and as its fourth
argument the previous value.</p>
</dd>
<dt><dfn title="datagrid-type-checkable"><code>checkable</code></dfn></dt>
<dd>
<p>The cell represents some text, a check box that optionally has
its value obscured as indeterminate, and an optional image.</p>
<p>When the user checks or unchecks the check box, the user agent
must change the check box's state appropriately and stop obscuring
the check box as indeterminate (if it is obscuring it), and then
must invoke the <code
title="dom-listener-cellChanged">cellChanged()</code> method on
the current <code title="dom-datagrid-listener">listener</code>
with as its first argument a <code>RowID</code> identifying the
cell's row, as its second argument the identifier of the cell's
column, as its third argument true if the check box is now checked
and false otherwise, and as its fourth argument true if the check
box was previously checked and false otherwise.</p>
</dd>
<dt><dfn title="datagrid-type-list"><code>list</code></dfn></dt>
<dd>
<p>The cell represents some text giving the current value selected
from a dropdown list of options, a <code>select</code> element
giving the list of options, and an optional image.</p>
<p>The user agent should allow the user to change the value of the
cell from its current value to one of the <span
title="concept-option-value">values</span> given by
<code>option</code> elements in the <span
title="concept-select-option-list">list of options</span> (if
any). The user agent may use the <code>option</code> elements'
<span title="concept-option-label">labels</span> to annotate each
option.</p>
<p>When the user selects a new value from the <code>select</code>
element's <span title="concept-select-option-list">list of
options</span>, the user agent must invoke the <code
title="dom-listener-cellChanged">cellChanged()</code> method on
the current <code title="dom-datagrid-listener">listener</code>
with as its first argument a <code>RowID</code> identifying the
cell's row, as its second argument the identifier of the cell's
column, as its third argument the new value, and as its fourth
argument the previous value.</p>
</dd>
<dt><dfn title="datagrid-type-progress"><code>progress</code></dfn></dt>
<dd>
<p>The cell represents a (determinate) progress bar whose value is
between 0.0, indicating no progress, and 1.0, indicating the task
is complete.</p>
</dd>
<dt><dfn title="datagrid-type-meter"><code>meter</code></dfn></dt>
<dd>
<p>The cell represents a gauge, described by one to six
numbers.</p>
<p>The gauge's actual value is given by the first number.</p>
<p>If there is a second number, then that number is the maximum
value. Otherwise, the maximum value is 1.0.</p>
<p>If there is a third number, then that number is the minimum
value. Otherwise, the minimum value is 1.0.</p>
<p>If there is a fourth number, then that number is the low
boundary. Otherwise, the low boundary is the minimum value.</p>
<p>If there is a fifth number, then that number is the high
boundary. Otherwise, the high boundary is the maximum value.</p>
<p>If there is a sixth number, then the optimal point is the sixth
number. Otherwise, the optimum point is the midpoint between the
minimum value and the maximum value.</p>
<!- - next two paragraphs copied from <meter>: - ->
<p>If the optimum point is equal to the low boundary or the high
boundary, or anywhere in between them, then the region between the
low and high boundaries of the gauge must be treated as the
optimum region, and the low and high parts, if any, must be
treated as suboptimal. Otherwise, if the optimum point is less
than the low boundary, then the region between the minimum value
and the low boundary must be treated as the optimum region, the
region between the low boundary and the high boundary must be
treated as a suboptimal region, and the region between the high
boundary and the maximum value must be treated as an even less
good region. Finally, if the optimum point is higher than the high
boundary, then the situation is reversed; the region between the
high boundary and the maximum value must be treated as the optimum
region, the region between the high boundary and the low boundary
must be treated as a suboptimal region, and the remaining region
between the low boundary and the minimum value must be treated as
an even less good region.</p>
<p>User agents should indicate the relative position of the actual
value to the minimum and maximum values, and the relationship
between the actual value and the three regions of the gauge.</p>
</dd>
<dt><dfn title="datagrid-type-custom"><code>custom</code></dfn></dt>
<dd>
<p>The cell represents a dynamically generated graphical image.</p>
<p>The cell will have minimum dimensions (specified in CSS
pixels), and a callback (in the form of a
<code>RenderingContext2DCallback</code> object) to get a rendering
for the cell.</p>
<p>The user agent should not allow the cell to be rendered with
dimensions less than the given minimum width and height.</p>
<p>When the user agent needs to render the cell, the user agent
must <span>queue a task</span> to invoke the
<span>RenderingContext2DCallback</span> callback, passing it a
newly created <code>CanvasRenderingContext2D</code> object whose
<code title="dom-context-2d-canvas">canvas</code> IDL attribute is
null as the first argument, the actual cell width in CSS pixels as
the second argument, and the actual cell height in CSS pixels as
the third argument.</p>
<p>If the user agent is able to render graphics, then it must
render the graphics commands that the callback executed on the
provided <code>CanvasRenderingContext2D</code> object onto the
cell once the callback returns. The image must be clipped to the
dimensions of the cell. The coordinate space of the cell must be
aligned with that used by the 2D context such that the top left
corner of the cell is the 0,0 origin, with the coordinate space
increasing its <var title="">x</var> dimension towards the right
of the cell and its <var title="">y</var> axis towards the bottom
of the cell, and with the image not scaled (so that one CSS pixel
on the final rendering matches one CSS pixel in the coordinate
space used by the 2D context).</p>
<p>The user agent must then decouple the
<code>CanvasRenderingContext2D</code> object and any objects that
it created (such as <code>CanvasPattern</code> objects or
<code>ImageData</code> objects) from any real drawing surface.</p>
<p>If the user agent is unable to render graphics, then it must
render the text string returned by the callback instead.</p>
</dd>
</dl>
<hr>
<p>When an algorithm requires the user agent to <dfn>apply a
<code>Row</code> object</dfn>, the user agent must run the following
steps:</p>
<ol>
<li>
<p>If the value of the <code>Row</code> object's second entry is
not −1, then run these substeps:</p>
<ol>
<li><p>If there is a row with the same parent as the row
specified by the <code>Row</code> object's <code>RowID</code>
object, whose display order position is currently the same as the
value of the <code>Row</code> object's second entry, then remove
that row from the <span>display order sparse data
tree</span>.</p></li>
<li><p>Set the display order position of the row specified by the
<code>Row</code> object's <code>RowID</code> to the value of the
<code>Row</code> object's second entry, updating its position in
the <span>display order sparse data tree</span>
accordingly.</p></li>
<li><p>If the row is in the <span>pending
<code>datagrid</code> rows list</span>, remove it.</p></li>
</ol>
</li>
<li>
<p>If the fourth entry in the <code>Row</code> object (a
<code>CellList</code> object, an array) is not empty, then for
each <code>Cell</code> object in that array update the cell that
corresponds to the column identified by the value of the first
entry of the <code>Cell</code> object, by using the appropriate
set of steps given below as determined by the type of the
column. Then, if the cell is in the <span>pending
<code>datagrid</code> cells list</span>, remove it.</p>
<dl>
<dt>If the column's type is <code title="datagrid-type-text">text</code></dt>
<dd>
<p>Update the cell's text to the value given in the
<code>Cell</code> object's second entry.</p>
<p>If the <code>Cell</code> object has three entries, then copy
the image data from the <code>img</code> element given in the
third entry, and let the cell's image be given by that image
data. Otherwise, update the cell to have no image.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-editable">editable</code></dt>
<dd>
<p>Update the cell's text to the value given in the
<code>Cell</code> object's second entry.</p>
<p>If the <code>Cell</code> object has three entries, then let
the <code>datalist</code> element given in the third entry be
the <code>datalist</code> element giving autocompletion
hints. Otherwise, update the cell to have no
<code>datalist</code> element.</p>
<p>If the <code>Cell</code> object has four entries, then copy
the image data from the <code>img</code> element given in the
fourth entry, and let the cell's image be given by that image
data. Otherwise, update the cell to have no image.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-checkable">checkable</code></dt>
<dd>
<p>Update the cell's text to the value given in the
<code>Cell</code> object's second entry.</p>
<p>Update the cell's checked state to match the value of the
third entry: checked if true, unchecked otherwise.</p>
<p>If the <code>Cell</code> object has four entries and the
fourth entry is true, then update the cell to be obscured as
indeterminate. Otherwise, the cell's state is not obscured.</p>
<p>If the <code>Cell</code> object has five entries, then copy
the image data from the <code>img</code> element given in the
fifth entry, and let the cell's image be given by that image
data. Otherwise, update the cell to have no image.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-list">list</code></dt>
<dd>
<p>Update the cell's text to the value given in the
<code>Cell</code> object's second entry, and the
<code>select</code> element to be the one given in the
<code>Cell</code> object's third entry</p>
<p>If the <code>Cell</code> object has four entries, then copy
the image data from the <code>img</code> element given in the
fourth entry, and let the cell's image be given by that image
data. Otherwise, update the cell to have no image.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-progress">progress</code></dt>
<dd>
<p>Update the cell to be a progress bar whose progress, on the
scale of 0.0 (no progress) to 1.0 (task complete) is given by
the value in the <code>Cell</code> object's second entry.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-meter">meter</code></dt>
<dd>
<p>Update the cell to be a gauge configured with the numbers
given by the second and subsequent entries of the
<code>Cell</code> object.</p>
</dd>
<dt>If the column's type is <code title="datagrid-type-custom">custom</code></dt>
<dd>
<p>Update the cell's minimum width to be the length in CSS
pixels given by the <code>Cell</code> object's second entry.</p>
<p>Update the cell's minimum height to be the length in CSS
pixels given by the <code>Cell</code> object's third entry.</p>
<p>Update the cell's callback to be the
<code>RenderingContext2DCallback</code> object given by the
<code>Cell</code> object's fourth entry.</p>
</dd>
</dl>
</li>
</ol>
<hr>
<p>When the user agent is to run the <dfn><code>datagrid</code>
update display algorithm</dfn>, the user agent must invoke the <code
title="dom-listener-getRows">getRows()</code> and <code
title="dom-listener-getCells">getCells()</code> methods on the
current <code title="dom-datagrid-listener">listener</code> such
that all the current visible rows in the <span>display order sparse
data list</span>, and all the cells in the currently visible columns
on all the currently visible rows, have been covered.</p>
<p>A row is considered covered if it is present in the <span>pending
<code>datagrid</code> rows list</span>, or if the <code
title="dom-listener-getRows">getRows()</code> method is invoked with
a range that includes the row in question.</p>
<p>A cell is considered covered if it is present in the
<span>pending <code>datagrid</code> cells list</span>, or if the
<code title="dom-listener-getRows">getRows()</code> method is
invoked with a range that includes the row in question and a list of
columns that includes the cell's column, or if the <code
title="dom-listener-getCells">getCells()</code> method is invoked
with a list of rows and columns that intersects the cell in
question. However, the <code
title="dom-listener-getCells">getCells()</code> method can only be
used if the row is already present in the <span>display order sparse
data list</span>.</p>
<p>The <code title="dom-listener-getRows">getRows()</code> method,
if used, must be invoked with five arguments. The first argument
must be the index in the <span>display order sparse data list</span>
to the first row that the user agent is requesting, known as the
<i>anchor row</i>. The second argument must be the number of
consecutive cells for which the user agent is requesting
information. The third argument must be the <code>RowID</code> of
the row that is the nearest ancestor in the <span>display order
sparse data <em>tree</em></span> of the anchor row. If this is the
<code>datagrid</code>, then the <code>RowID</code> object must be an
empty array. The fourth argument must be the display order position
of the anchor row in the <span>display order sparse data
tree</span>, assuming that the row identified in the third argument
is indeed the anchor row's parent row. The fifth and final argument
must be an array of the identifiers of the columns for which the
user agent is requesting information, in the order they were added
to the <code>datagrid</code>.</p>
<p>As the <code title="dom-listener-getRows">getRows()</code> method
is invoked, the <span>pending <code>datagrid</code> rows list</span>
must be updated to include the rows for which information has been
requested, excluding rows for which information is already
available; and the <span>pending <code>datagrid</code> cells
list</span> must be updated to include the cells for which
information has been requested on those rows.</p>
<p>The <code title="dom-listener-getCells">getCells()</code> method,
if used, must be invoked with two arguments. The first argument must
be an array of <code>RowID</code> objects identifying the rows for
which information is being requested. The second argument must be an
array of the identifiers of the columns for which the user agent is
requesting information, in the order they were added to the
<code>datagrid</code>.</p>
<p>As the <code title="dom-listener-getCells">getCells()</code>
method is invoked, the <span>pending <code>datagrid</code> cells
list</span> must be updated to include the cells for which
information has been requested.</p>
<p>Calls to these methods should be batched so that the rows and
cells to be covered are handled by the fewest number of calls to
these methods as possible. To this end, user agents may invoke the
<code title="dom-listener-getRows">getRows()</code> method for a set
of rows that includes some rows that are already in the
<span>display order sparse data list</span>, and similarly may
invoke the <code title="dom-listener-getCells">getCells()</code>
method with row/column combinations that cover some cells for which
data is already known. Generally, however, user agents should avoid
invoking these methods with arguments that cause information to be
requested when it has already been requested or is already
known.</p>
<div class="example">
<p>For example, consider a case represented by the following table,
where the cells marked "Yes" indicate that the data has already
been obtained, the cells marked "Pending" indicate that the data
has been previously requested but not yet obtained, and the cells
with just a dash indicate that no information has ever been
obtained, or any information that had been obtained has now been
discarded.</p>
<table>
<tr> <td> <th> Row <th> Column A <th> Column B
<tr> <th> Row 1 <td> - <td> - <td> -
<tr> <th> Row 2 <td> Yes <td> Yes <td> Yes
<tr> <th> Row 3 <td> Yes <td> Yes <td> Yes
<tr> <th> Row 4 <td> Yes <td> Yes <td> Yes
<tr> <th> Row 5 <td> - <td> - <td> -
<tr> <th> Row 6 <td> - <td> - <td> -
<tr> <th> Row 7 <td> Yes <td> Pending <td> -
<tr> <th> Row 8 <td> Yes <td> Pending <td> Pending
</table>
<p>Thus, rows 2, 3, 4, 7, and 8 are already covered, as are the
cells from those rows except for the cell in column B of row 7.</p>
<p>Now consider what happens if all of these rows become visible at
once. The user agent has several choices, including (but not
limited to) the following:</p>
<ul>
<li>Fire the <code title="dom-listener-getRows">getRows()</code>
method for rows 1 through 8 and columns A and B all at once.</li>
<li>Fire the <code title="dom-listener-getRows">getRows()</code>
method for row 1, then fire it again for rows 5 through 7.</li>
<li>Fire the <code title="dom-listener-getRows">getRows()</code>
method for row 1, then fire it again for rows 5 and 6, and then
fire the <code title="dom-listener-getCells">getCells()</code>
method for row 7 column B.</li>
</ul>
<p>All three options are allowed, but the latter two are preferable
to the former, as they minimise the amount of redundant information
requested.</p>
<p>In any case, the data model now looks like this:</p>
<table>
<tr> <td> <th> Row <th> Column A <th> Column B <th> Column C
<tr> <th> Row 1 <td> Pending <td> Pending <td> Pending <td> -
<tr> <th> Row 2 <td> Yes <td> Yes <td> Yes <td> -
<tr> <th> Row 3 <td> Yes <td> Yes <td> Yes <td> -
<tr> <th> Row 4 <td> Yes <td> Yes <td> Yes <td> -
<tr> <th> Row 5 <td> Pending <td> Pending <td> Pending <td> -
<tr> <th> Row 6 <td> Pending <td> Pending <td> Pending <td> -
<tr> <th> Row 7 <td> Yes <td> Pending <td> Pending <td> -
<tr> <th> Row 8 <td> Yes <td> Pending <td> Pending <td> -
</table>
<p>Now consider the case where a third column, column C, is added
to the data model. The user agent once again has several choices,
including (but not limited to) the following:</p>
<ul>
<li>Fire the <code title="dom-listener-getRows">getRows()</code>
method for rows 1 through 8 again, this time listing just column
C.</li>
<li>Fire the <code title="dom-listener-getRows">getRows()</code>
method for row 1, then fire it again for rows 5 and 6, and then
fire the <code title="dom-listener-getCells">getCells()</code>
method for the other rows (in all three cases, listing just column
C).</li>
</ul>
<p>The two options here are as bad as each other; the former
involves a lot of overlap, but the latter involves a lot of method
calls. Unfortunately the user agent can't do the obvious thing,
namely just to invoke the <code
title="dom-listener-getCells">getCells()</code> method for all the
rows listing just column C, because it doesn't have the row
information for all the rows yet (rows 1, 5 and 6 are still
pending).</p>
<p>In any case, the data model now looks like this:</p>
<table>
<tr> <td> <th> Row <th> Column A <th> Column B <th> Column C
<tr> <th> Row 1 <td> Pending <td> Pending <td> Pending <td> Pending
<tr> <th> Row 2 <td> Yes <td> Yes <td> Yes <td> Pending
<tr> <th> Row 3 <td> Yes <td> Yes <td> Yes <td> Pending
<tr> <th> Row 4 <td> Yes <td> Yes <td> Yes <td> Pending
<tr> <th> Row 5 <td> Pending <td> Pending <td> Pending <td> Pending
<tr> <th> Row 6 <td> Pending <td> Pending <td> Pending <td> Pending
<tr> <th> Row 7 <td> Yes <td> Pending <td> Pending <td> Pending
<tr> <th> Row 8 <td> Yes <td> Pending <td> Pending <td> Pending
</table>
<p>If at this point the user scrolls around anywhere within this
<code>datagrid</code>, the user agent won't fire the <code
title="dom-listener-getRows">getRows()</code> and <code
title="dom-listener-getCells">getCells()</code> methods, because
all of the rows and cells are covered.</p>
<p>Now consider the case where the user agent receives row
information, but no cell information, for rows 1, 5, and 6:</p>
<table>
<tr> <td> <th> Row <th> Column A <th> Column B <th> Column C
<tr> <th> Row 1 <td> Yes <td> Pending <td> Pending <td> Pending
<tr> <th> Row 2 <td> Yes <td> Yes <td> Yes <td> Pending
<tr> <th> Row 3 <td> Yes <td> Yes <td> Yes <td> Pending
<tr> <th> Row 4 <td> Yes <td> Yes <td> Yes <td> Pending
<tr> <th> Row 5 <td> Yes <td> Pending <td> Pending <td> Pending
<tr> <th> Row 6 <td> Yes <td> Pending <td> Pending <td> Pending
<tr> <th> Row 7 <td> Yes <td> Pending <td> Pending <td> Pending
<tr> <th> Row 8 <td> Yes <td> Pending <td> Pending <td> Pending
</table>
<p>The user agent still won't fire any methods when the user
scrolls, because the data is still covered. But if the script then
calls the <code title="dom-datagrid-renotify">renotify()</code>
method, the "Pending" flags would get reset, and the model would
now look like this:</p>
<table>
<tr> <td> <th> Row <th> Column A <th> Column B <th> Column C
<tr> <th> Row 1 <td> Yes <td> - <td> - <td> -
<tr> <th> Row 2 <td> Yes <td> Yes <td> Yes <td> -
<tr> <th> Row 3 <td> Yes <td> Yes <td> Yes <td> -
<tr> <th> Row 4 <td> Yes <td> Yes <td> Yes <td> -
<tr> <th> Row 5 <td> Yes <td> - <td> - <td> -
<tr> <th> Row 6 <td> Yes <td> - <td> - <td> -
<tr> <th> Row 7 <td> Yes <td> - <td> - <td> -
<tr> <th> Row 8 <td> Yes <td> - <td> - <td> -
</table>
<p>Now, assuming that all eight rows and all three columns are
still visible, the user agent has the following choices (amongst
others):</p>
<ul>
<li>Fire the <code title="dom-listener-getRows">getCells()</code>
method for rows 1 through 8, listing all three columns.</li>
<li>Fire the <code title="dom-listener-getRows">getCells()</code>
method for rows 1 and 5 through 8, listing all three columns, and
then fire the method for rows 2 through 4, listing just column
C.</li>
<li>Fire the <code title="dom-listener-getRows">getCells()</code>
method for rows 1 and 5 through 8, listing just columns A abd B,
and then fire the method for rows 1 through 8, listing just column
C.</li>
</ul>
<p>Here the latter two are preferable because they result in less
overlap than the first.</p>
</div>
<hr>
<p>The <span>task source</span> for tasks queued on behalf of a
<code>datagrid</code> is the <span>DOM manipulation task
source</span>.</p>
</div>
<h5>Listening to notifications from the <code>datagrid</code></h5>
<p><i>The conformance criteria in this section apply to any
implementation of the <code>DataGridListener</code> interface,
including (and most commonly) the content author's
implementation(s).</i></p>
<pre class="idl">// To be implemented by Web authors as a JS object
[NoInterfaceObject]
interface <dfn>DataGridListener</dfn> {
void <span title="dom-listener-initialize">initialize</span>(in <span>HTMLDataGridElement</span> datagrid);
void <span title="dom-listener-getRows">getRows</span>(in unsigned long rowIndex, in unsigned long rowCount, in <span>RowID</span> parentRow, in unsigned long position, in <span>ColumnList</span> columns);
void <span title="dom-listener-getCells">getCells</span>(in <span>RowIDList</span> rows, in <span>ColumnList</span> columns);
void <span title="dom-listener-rowOpened">rowOpened</span>(in <span>RowID</span> row, in boolean rowCountNeeded);
void <span title="dom-listener-rowClosed">rowClosed</span>(in <span>RowID</span> row);
void <span title="dom-listener-cellChanged">cellChanged</span>(in <span>RowID</span> row, in <span>Column</span> column, in any newValue, in any prevValue);
<span>HTMLMenuElement</span> <span title="dom-listener-getRowMenu">getRowMenu</span>(in <span>RowID</span> row);
<!- -vsDGDND
boolean <span title="dom-listener-canDrop">canDrop</span>(in <span>RowID</span> row, in <span>RowID</span> position, data);
boolean <span title="dom-listener-dropped">dropped</span>(in <span>RowID</span> row, in <span>RowID</span> position, data);
- -><!- -v2DGPA
void <span title="dom-listener-performAction">performAction</span>(in <span>RowID</span> row, in DOMString action);
- ->};</pre>
<p>The <code>DataGridListener</code> interface, once implemented by
an object in a script and hooked up to a <code>datagrid</code> using
the <code title="dom-datagrid-listener">listener</code> IDL
attribute, receives notifications when the <code>datagrid</code>
needs information (such as which rows exist) for display.</p>
<p>The following methods may be usefully implemented:</p>
<dl>
<dt><dfn title="dom-listener-initialize"><code>initialize(<var title="">datagrid</var>)</code></dfn></dt>
<dd>
<p>Called by the <code>datagrid</code> element (the one given by
the <var title="">datagrid</var> argument) when the <code
title="dom-datagrid-listener">listener</code> attribute is
set.</p>
</dd>
<dt><dfn title="dom-listener-getRows"><code>getRows(<var title="">rowIndex</var>, <var title="">rowCount</var>, <var title="">parentRow</var>, <var title="">position</var>, <var title="">columns</var>)</code></dfn></dt>
<dd>
<p>Called by the <code>datagrid</code> element when the user agent
finds itself needing to render rows for which it is lacking
information.</p>
<p>The <var title="">rowIndex</var> argument gives the flattened
index of the first row for which it needs information, ignoring
the tree structure of the <code>datagrid</code> model, where zero
is the first row of the entire tree.</p>
<p>The <var title="">rowCount</var> argument gives the number of
rows for which the user agent would like information.</p>
<p>The <var title="">parentRow</var> argument gives the
<code>RowID</code> object identifying the nearest ancestor of the
first row that the user agent is aware of. After the sort order
has changed, this will typically be the root of the tree
(identified by a <code>RowID</code> object consisting of an empty
array).
<p>The <var title="">columns</var> argument gives the columns for
which the user agent is lacking information, as an array of column
identifiers (as passed to <code
title="dom-datagrid-addColumn">addColumn()</code>).</p>
</dd>
<dt><dfn title="dom-listener-getCells"><code>getCells(<var title="">rows</var>, <var title="">columns</var>)</code></dfn></dt>
<dd>
<p>Called by the <code>datagrid</code> element when the user agent
finds itself needing to render cells for which it is lacking
information in rows that it does know about.</p>
<p>The <var title="">rows</var> argument gives an array of
<code>RowID</code> objects identifying the various rows for which
the user agent is lacking information.</p>
<p>The <var title="">columns</var> argument gives the columns for
which the user agent is lacking information, as an array of column
identifiers (as passed to <code
title="dom-datagrid-addColumn">addColumn()</code>).</p>
</dd>
<dt><dfn title="dom-listener-rowOpened"><code>rowOpened(<var title="">row</var>, <var title="">rowCountNeeded</var>)</code></dfn></dt>
<dd>
<p>Called by the <code>datagrid</code> element when the user has
opened a row.</p>
<p>The <var title="">row</var> argument gives an
<code>RowID</code> object identifying the row that was opened.</p>
<p>If the user agent also knows how many children that row has,
then the <var title="">rowCountNeeded</var> argument will be
false. Otherwise, the argument will be true, and the row will
remain closed until the <code
title="dom-datagrid-setRows">setRows()</code> method is called
with an accurate row count.</p>
</dd>
<dt><dfn title="dom-listener-rowClosed"><code>rowClosed(<var title="">row</var>)</code></dfn></dt>
<dd>
<p>Called by the <code>datagrid</code> element when the user has
opened a row.</p>
<p>The <var title="">row</var> argument gives an
<code>RowID</code> object identifying the row that was closed.</p>
</dd>
<dt><dfn title="dom-listener-cellChanged"><code>cellChanged(<var title="">row</var>, <var title="">column</var>, <var title="">newValue</var>, <var title="">prevValue</var>)</code></dfn></dt>
<dd>
<p>Called by the <code>datagrid</code> element when the user has
edited a cell or checked a check box in a cell.</p>
<p>The <var title="">row</var> argument gives an
<code>RowID</code> object identifying the row of the cell, and the
<var title="">column</var> argument gives the identifier of the
cell's column.</p>
<p>The <var title="">newValue</var> argument gives the new value,
and the <var title="">prevValue</var> argument gives the previous
value.</p>
</dd>
<dt><dfn title="dom-listener-getRowMenu"><code>getRowMenu(<var title="">row</var>)</code></dfn></dt>
<dd>Must return an <code>HTMLMenuElement</code> object that is to
be used as a context menu for row <var title="">row</var>, or null
if there is no particular context menu. May be omitted if none of
the rows have a special context menu. As this method is called
immediately before showing the menu in question, no precautions
need to be taken if the return value of this method changes.</dd>
<!- -v2DGDND, v2DFPA- ->
</dl>
<div class="impl">
<p>Objects that implement the <code>DataGridListener</code>
interface may omit any or all of the methods. When a method is
omitted, a user agent intending to call that method must instead
skip the method call, and must assume that the method's return value
is null.</p>
</div>
<!- - v2DGS: <datagrid> selection (search for the bits marked "..." to see what needs filling in, at a minimum)
<h5>The selection</h5>
<pre class="idl">interface <dfn>DataGridSelection</dfn> {
readonly attribute unsigned long <span title="dom-DataGridSelection-length">length</span>;
getter <span>RowID</span> <span title="dom-DataGridSelection-item">item</span>(in unsigned long index);
boolean <span title="dom-DataGridSelection-isSelected">isSelected</span>(in <span>RowID</span> row);
void <span title="dom-DataGridSelection-setSelected">setSelected</span>(in <span>RowID</span> row, in boolean selected);
void <span title="dom-DataGridSelection-selectAll">selectAll</span>();
void <span title="dom-DataGridSelection-clear">clear</span>();
};</pre>
<dl class="domintro">
...
</dl>
<div class="impl">
<p>Each <code>datagrid</code> element must keep track of which rows
are currently selected. Initially, no rows are selected. This can be
changed using the methods described in this section.</p>
<p>The selection of a <code>datagrid</code> is represented by its
<dfn title="dom-datagrid-selection"><code>selection</code></dfn> IDL
attribute, which must be a <code>DataGridSelection</code> object.</p>
<p><code>DataGridSelection</code> objects represent the rows in the
selection. In the selection the rows must be ordered in their
natural order (and not, e.g., the display order). A row with an
ancestor that is closed cannot be selected.</p>
<p>The <dfn
title="dom-DataGridSelection-length"><code>length</code></dfn>
attribute must return the number of rows currently present in the
selection. This is the <var
title="dom-DataGridSelection-length">length</var>.</p>
<p>The object's <span>indices of the supported indexed
properties</span> are the numbers in the range zero to <span title=""><var
title="dom-DataGridSelection-length">length</var>-1</span>, unless
the <var title="dom-DataGridSelection-length">length</var> is zero,
in which case there are no <span>supported indexed
properties</span>.</p>
<p>The <dfn title="dom-DataGridSelection-item"><code>item(<var
title="">index</var>)</code></dfn> method must return a
<code>RowID</code> object identifying the <var
title="">index</var>th row in the selection. If the argument is out
of range (less than zero or greater than the number of selected rows
minus one), then it must raise an <code>INDEX_SIZE_ERR</code>
exception. <a href="#refsDOMCORE">[DOMCORE]</a></p>
<p>The <dfn
title="dom-DataGridSelection-isSelected"><code>isSelected()</code></dfn>
method must return the selected state of the row specified by its
argument. If the specified row is in the <span>natural order sparse
data tree</span> and is selected, the method must return true,
otherwise it must return false.</p>
<p>The <dfn
title="dom-DataGridSelection-setSelected"><code>setSelected()</code></dfn>
method takes two arguments, <var title="">row</var> and <var
title="">selected</var>. When invoked, it must set the selection
state of row <var title="">row</var> to selected if <var
title="">selected</var> is true, and unselected if it is false. If
<var title="">row</var> does not specify a row in the <span>natural
order sparse data tree</span> ...
<p>The <dfn
title="dom-DataGridSelection-selectAll"><code>selectAll()</code></dfn>
method must ...
<p>The <dfn
title="dom-DataGridSelection-clear"><code>clear()</code></dfn>
method must mark all the rows in the <code>datagrid</code> as not
selected. After a call to <code
title="dom-DataGridSelection-clear">clear()</code>, the <code
title="dom-DataGridSelection-length">length</code> attribute will
return zero.</p>
<p>If the <code>datagrid</code> element has a <code
title="attr-datagrid-multiple">multiple</code> attribute, then the
user agent should allow the user to select any number of rows (zero
or more). If the attribute is not present, then the user agent
should allow the user to select a row, and must not allow the user
to select more than a single row at a time; selecting another one
must unselect all the other rows.</p>
<p class="note">This only applies to the user. Scripts can select
multiple rows even when the <code
title="attr-datagrid-multiple">multiple</code> attribute is
absent.</p>
...event on selection change?...
</div>
<p class="note">The <code>DataGridSelection</code> interface has no
relation to the <code>Selection</code> interface.</p>
- ->
<!- -vsDGDND
<h5>Drag and drop in <code>datagrid</code>s</h5>
<p><i>This section only applies to interactive user agents.</i></p>
...define drag and drop in datagrids; selectiondraggable...
- ->
-->
<h4 id="the-command">The <dfn><code>command</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Metadata content</span>.</dd>
<dd><span>Flow content</span>.</dd>
<dd><span>Phrasing content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>metadata content</span> is expected.</dd>
<dd>Where <span>phrasing content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Empty.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-command-type">type</code></dd>
<dd><code title="attr-command-label">label</code></dd>
<dd><code title="attr-command-icon">icon</code></dd>
<dd><code title="attr-command-disabled">disabled</code></dd>
<dd><code title="attr-command-checked">checked</code></dd>
<dd><code title="attr-command-radiogroup">radiogroup</code></dd>
<!--<dd><code title="attr-command-default">default</code></dd>-->
<dd>Also, the <code title="attr-command-title">title</code> attribute has special semantics on this element.</dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLCommandElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-command-type">type</span>;
attribute DOMString <span title="dom-command-label">label</span>;
attribute DOMString <span title="dom-command-icon">icon</span>;
attribute boolean <span title="dom-command-disabled">disabled</span>;
attribute boolean <span title="dom-command-checked">checked</span>;
attribute DOMString <span title="dom-command-radiogroup">radiogroup</span>;<!--
attribute boolean <span title="dom-command-default">default</span>;-->
};</pre>
</dd>
</dl>
<p>The <code>command</code> element represents a command that the user
can invoke.</p>
<p>The <dfn title="attr-command-type"><code>type</code></dfn>
attribute indicates the kind of command: either a normal command
with an associated action, or a state or option that can be toggled,
or a selection of one item from a list of items.</p>
<p>The attribute is an <span>enumerated attribute</span> with three
keywords and states. The "<dfn
title="attr-command-type-keyword-command"><code>command</code></dfn>"
keyword maps to the <span
title="attr-command-type-state-command">Command</span> state, the
"<dfn
title="attr-command-type-keyword-checkbox"><code>checkbox</code></dfn>"
keyword maps to the <span
title="attr-command-type-state-checkbox">Checkbox</span> state, and
the "<dfn
title="attr-command-type-keyword-radio"><code>radio</code></dfn>"
keyword maps to the <span
title="attr-command-type-state-radio">Radio</span> state. The
<i>missing value default</i> is the <span
title="attr-command-type-state-command">Command</span> state.</p>
<dl>
<dt>The <dfn title="attr-command-type-state-command">Command</dfn> state</dt>
<dd><p>The element <span>represents</span> a normal command with an associated action.</p></dd>
<dt>The <dfn title="attr-command-type-state-checkbox">Checkbox</dfn> state</dt>
<dd><p>The element <span>represents</span> a state or option that can be toggled.</p></dd>
<dt>The <dfn title="attr-command-type-state-radio">Radio</dfn> state</dt>
<dd><p>The element <span>represents</span> a selection of one item from a list of items.</p></dd>
</dl>
<p>The <dfn title="attr-command-label"><code>label</code></dfn>
attribute gives the name of the command, as shown to the user.</p>
<p>The <dfn title="attr-command-title"><code>title</code></dfn>
attribute gives a hint describing the command, which might be shown
to the user to help him.</p>
<p>The <dfn title="attr-command-icon"><code>icon</code></dfn>
attribute gives a picture that represents the command. If the
attribute is specified, the attribute's value must contain a
<span>valid URL</span>. <span class="impl">To obtain the
<span>absolute URL</span> of the icon, the attribute's value must be
<span title="resolve a url">resolved</span> relative to the
element.</span></p> <!-- this is affected by the base URL being
changed, so users of this should cache the image once they've
fetched it once, at least until the relative url changes again -->
<p>The <dfn
title="attr-command-disabled"><code>disabled</code></dfn> attribute
is a <span>boolean attribute</span> that, if present, indicates that
the command is not available in the current state.</p>
<p class="note">The distinction between <code
title="attr-command-disabled">disabled</code> and <code
title="attr-hidden">hidden</code> is subtle. A command would be
disabled if, in the same context, it could be enabled if only
certain aspects of the situation were changed. A command would be
marked as hidden if, in that situation, the command will never be
enabled. For example, in the context menu for a water faucet, the
command "open" might be disabled if the faucet is already open, but
the command "eat" would be marked hidden since the faucet could
never be eaten.</p>
<p>The <dfn title="attr-command-checked"><code>checked</code></dfn>
attribute is a <span>boolean attribute</span> that, if present,
indicates that the command is selected. The attribute must be
omitted unless the <code title="attr-command-type">type</code>
attribute is in either the <span
title="attr-command-type-state-checkbox">Checkbox</span> state or
the <span title="attr-command-type-state-radio">Radio</span>
state.</p>
<p>The <dfn
title="attr-command-radiogroup"><code>radiogroup</code></dfn>
attribute gives the name of the group of commands that will be
toggled when the command itself is toggled, for commands whose <code
title="attr-command-type">type</code> attribute has the value "<code
title="">radio</code>". The scope of the name is the child list of
the parent element. The attribute must be omitted unless the <code
title="attr-command-type">type</code> attribute is in the <span
title="attr-command-type-state-radio">Radio</span> state.</p>
<!--
<p>If the <code>command</code> element is used when <span
title="menu generation">generating</span> a <span>context
menu</span>, then the <dfn
title="attr-command-default"><code>default</code></dfn> attribute
indicates, if present, that the command is the one that would have
been invoked if the user had directly activated the menu's subject
instead of using its context menu. The <code
title="attr-command-default">default</code> attribute is a
<span>boolean attribute</span>. The attribute must be omitted unless
the <code title="attr-command-type">type</code> attribute is in the
<span title="attr-command-type-state-command">Command</span>
state.</p>
<div class="example">
...an example that shows an element that, if double-clicked,
invokes an action, but that also has a context menu, showing the
various <code>command</code> attributes off, and that has a default
command...
</div>
-->
<div class="impl">
<p>The <dfn title="dom-command-type"><code>type</code></dfn>, <dfn
title="dom-command-label"><code>label</code></dfn>, <dfn
title="dom-command-icon"><code>icon</code></dfn>, <dfn
title="dom-command-disabled"><code>disabled</code></dfn>, <dfn
title="dom-command-checked"><code>checked</code></dfn>, and <dfn
title="dom-command-radiogroup"><code>radiogroup</code></dfn><!--,
and <dfn title="dom-command-default"><code>default</code></dfn>-->
IDL attributes must <span>reflect</span> the respective content
attributes of the same name.</p>
<p>The element's <span>activation behavior</span> depends on the
value of the <code title="attr-command-type">type</code> attribute
of the element, as follows:</p>
<dl class="switch">
<dt>If the <code title="attr-command-type">type</code> attribute is
in the <span
title="attr-command-type-state-checkbox">Checkbox</span> state</dt>
<dd><p>If the element has a <code
title="attr-command-checked">checked</code> attribute, the UA must
remove that attribute. Otherwise, the UA must add a <code
title="attr-command-checked">checked</code> attribute, with the
literal value <code title="">checked</code>. The UA must then
<span>fire a <code title="event-click">click</code> event</span> at the
element.</p></dd>
<dt>If the <code title="attr-command-type">type</code> attribute is
in the <span
title="attr-command-type-state-radio">Radio</span> state</dt>
<dd><p>If the element has a parent, then the UA must walk the list
of child nodes of that parent element, and for each node that is a
<code>command</code> element, if that element has a <code
title="attr-command-radiogroup">radiogroup</code> attribute whose
value exactly matches the current element's (treating missing <code
title="attr-command-radiogroup">radiogroup</code> attributes as if
they were the empty string), and has a <code
title="attr-command-checked">checked</code> attribute, must remove
that attribute.</p>
<p>Then, the element's <code
title="attr-command-checked">checked</code> attribute attribute
must be set to the literal value <code title="">checked</code> and
the user agent must <span>fire a <code title="event-click">click</code>
event</span> at the element.</p></dd>
<dt>Otherwise</dt>
<dd><p>The element has no <span>activation behavior</span>.</p></dd>
</dl>
<p class="note">Firing a synthetic <code
title="event-click">click</code> event at the element does not cause
any of the actions described above to happen.</p>
<!-- v2COMMAND: the command="" attribute to make a <command> element
reflect the state of another command, so that the script can update
one place in the page and have context menus, toolbars, shortcuts,
etc, automatically update. Once we add this, expose the Triggers
facet again. -->
</div>
<p class="note"><code>command</code> elements are not rendered
unless they <span title="menu">form part of a menu</span>.</p>
<div class="example">
<p>Here is an example of a toolbar with three buttons that let the
user toggle between left, center, and right alignment. One could
imagine such a toolbar as part of a text editor. The toolbar also
has a separator followed by another button labeled "Publish",
though that button is disabled.</p>
<pre><menu type="toolbar">
<command type="radio" radiogroup="alignment" checked="checked"
label="Left" icon="icons/alL.png" onclick="setAlign('left')">
<command type="radio" radiogroup="alignment"
label="Center" icon="icons/alC.png" onclick="setAlign('center')">
<command type="radio" radiogroup="alignment"
label="Right" icon="icons/alR.png" onclick="setAlign('right')">
<hr>
<command type="command" disabled
label="Publish" icon="icons/pub.png" onclick="publish()">
</menu></pre>
</div>
<h4 id="menus">The <dfn><code>menu</code></dfn> element</h4>
<dl class="element">
<dt>Categories</dt>
<dd><span>Flow content</span>.</dd>
<dd>If the element's <code title="attr-menu-type">type</code> attribute is in the <span title="toolbar state">toolbar</span> state: <span>Interactive content</span>.</dd>
<dt>Contexts in which this element may be used:</dt>
<dd>Where <span>flow content</span> is expected.</dd>
<dt>Content model:</dt>
<dd>Either: Zero or more <code>li</code> elements.</dd>
<dd>Or: <span>Flow content</span>.</dd>
<dt>Content attributes:</dt>
<dd><span>Global attributes</span></dd>
<dd><code title="attr-menu-type">type</code></dd>
<dd><code title="attr-menu-label">label</code></dd>
<dt>DOM interface:</dt>
<dd>
<pre class="idl">interface <dfn>HTMLMenuElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-menu-type">type</span>;
attribute DOMString <span title="dom-menu-label">label</span>;
};</pre>
</dl>
<p>The <code>menu</code> element represents a list of commands.</p>
<!-- v2 idea: <menu> should get an icon, like <command> -->
<p>The <dfn title="attr-menu-type"><code>type</code></dfn> attribute
is an <span>enumerated attribute</span> indicating the kind of menu
being declared. The attribute has three states. The <code
title="attr-menu-type-context">context</code> keyword maps to the
<dfn title="context menu state">context menu</dfn> state, in which
the element is declaring a context menu. The <code
title="attr-menu-type-toolbar">toolbar</code> keyword maps to the
<dfn title="toolbar state">toolbar</dfn> state, in which the
element is declaring a toolbar. The attribute may also be
omitted. The <i>missing value default</i> is the <dfn title="list
state">list</dfn> state, which indicates that the element is merely
a list of commands that is neither declaring a context menu nor
defining a toolbar.</p>
<p>If a <code>menu</code> element's <code
title="attr-menu-type">type</code> attribute is in the <span
title="context menu state">context menu</span> state, then the
element <span>represents</span> the commands of a context menu, and
the user can only interact with the commands if that context menu is
activated.</p>
<p>If a <code>menu</code> element's <code
title="attr-menu-type">type</code> attribute is in the <span
title="toolbar state">toolbar</span> state, then the element
<span>represents</span> a list of active commands that the user can
immediately interact with.</p>
<p>If a <code>menu</code> element's <code
title="attr-menu-type">type</code> attribute is in the <span
title="list state">list</span> state, then the element either
<span>represents</span> an unordered list of items (each represented
by an <code>li</code> element), each of which represents a command
that the user can perform or activate, or, if the element has no
<code>li</code> element children, <span>flow content</span>
describing available commands.</p>
<p>The <dfn title="attr-menu-label"><code>label</code></dfn>
attribute gives the label of the menu. It is used by user agents to
display nested menus in the UI. For example, a context menu
containing another menu would use the nested menu's <code
title="attr-menu-label">label</code> attribute for the submenu's
menu label.</p>
<div class="impl">
<p>The <dfn title="dom-menu-type"><code>type</code></dfn> and <dfn
title="dom-menu-label"><code>label</code></dfn> IDL attributes must
<span>reflect</span> the respective content attributes of the same
name.</p>
</div>
<h5 id="menus-intro">Introduction</h5>
<p><i>This section is non-normative.</i></p>
<p>The <code>menu</code> element is used to define context menus and
toolbars.</p>
<p>For example, the following represents a toolbar with three menu
buttons on it, each of which has a dropdown menu with a series of
options:</p>
<pre><menu type="toolbar">
<li>
<menu label="File">
<button type="button" onclick="fnew()">New...</button>
<button type="button" onclick="fopen()">Open...</button>
<button type="button" onclick="fsave()">Save</button>
<button type="button" onclick="fsaveas()">Save as...</button>
</menu>
</li>
<li>
<menu label="Edit">
<button type="button" onclick="ecopy()">Copy</button>
<button type="button" onclick="ecut()">Cut</button>
<button type="button" onclick="epaste()">Paste</button>
</menu>
</li>
<li>
<menu label="Help">
<li><a href="help.html">Help</a></li>
<li><a href="about.html">About</a></li>
</menu>
</li>
</menu></pre>
<p>In a supporting user agent, this might look like this:</p>
<p><img src="images/sample-toolbar-1.png" alt="A toolbar with three buttons, labeled 'File', 'Edit', and 'Help'; where if you select the 'Edit' button you get a drop-down menu with three more options, 'Copy', 'Cut', and 'Paste'."></p>
<p>In a legacy user agent, the above would look like a bulleted list
with three items, the first of which has four buttons, the second of
which has three, and the third of which has two nested bullet points
with two items consisting of links.</p>
<hr>
<p>The following implements a similar toolbar, with a single button
whose values, when selected, redirect the user to Web sites.</p>
<pre><form action="redirect.cgi">
<menu type="toolbar">
<label for="goto">Go to...</label>
<menu label="Go">
<select id="goto"
onchange="if (this.options[this.selectedIndex].value)
window.location = this.options[this.selectedIndex].value">
<option value="" selected="selected"> Select site: </option>
<option value="http://www.apple.com/"> Apple </option>
<option value="http://www.mozilla.org/"> Mozilla </option>
<option value="http://www.opera.com/"> Opera </option>
</select>
<span><input type="submit" value="Go"></span>
</menu>
</menu>
</form></pre>
<p>The behavior in supporting user agents is similar to the example
above, but here the legacy behaviour consists of a single
<code>select</code> element with a submit button. The submit button
doesn't appear in the toolbar, because it is not a direct child of
the <code>menu</code> element or of its <code>li</code>
children.</p>
<div class="impl">
<h5><dfn>Building menus and toolbars</dfn></h5>
<p>A menu (or toolbar) consists of a list of zero or more of the
following components:</p>
<ul class="brief">
<li><span title="concept-command">Commands</span>, which can be marked as default commands</li>
<li>Separators</li>
<li>Other menus (which allows the list to be nested)</li>
</ul>
<p>The list corresponding to a particular <code>menu</code> element
is built by iterating over its child nodes. For each child node in
<span>tree order</span>, the required behavior depends on what the
node is, as follows:</p>
<dl class="switch">
<dt>An element that <span title="concept-command">defines a command</span></dt>
<dd>Append the command to the menu, respecting its <span
title="concept-facet">facets</span><!-- we might need to be
explicit about what this means for each facet, if testing shows
this isn't well-implemented. e.g.: If there's an Icon facet for the
command, it should be <span title="fetch">fetched</span> (this
would be http-origin privacy-sensitive), and then that image should
be associated with the command, such that each command only has its
image fetched once, to prevent changes to the base URL from having
effects after the image has been fetched once. (no need to resolve
the Icon facet, it's an absolute URL) -->. <!--If the element is a
<code>command</code> element with a <code
title="attr-command-default">default</code> attribute, mark the
command as being a default command.--></dd>
<dt>An <code>hr</code> element</dt>
<dt>An <code>option</code> element that has a <code
title="attr-option-value">value</code> attribute set to the empty
string, and has a <code
title="attr-option-disabled">disabled</code> attribute, and whose
<code>textContent</code> consists of a string of one or more
hyphens (U+002D HYPHEN-MINUS)</dt>
<dd>Append a separator to the menu.</dd>
<dt>An <code>li</code> element</dt>
<dt>A <code>label</code> element</dt>
<dd>Iterate over the children of the element.</dd>
<dt>A <code>menu</code> element with no <code title="attr-menu-label">label</code> attribute</dt>
<dt>A <code>select</code> element</dt>
<dd>Append a separator to the menu, then iterate over the children
of the <code>menu</code> or <code>select</code> element, then
append another separator.</dd>
<!-- v2: we might want to support <select> in <label> as giving a named submenu -->
<dt>A <code>menu</code> element with a <code title="attr-menu-label">label</code> attribute</dt>
<dt>An <code>optgroup</code> element with a <code title="attr-menu-label">label</code> attribute</dt>
<dd>Append a submenu to the menu, using the value of the element's
<code title="">label</code> attribute as the label of the menu. The
submenu must be constructed by taking the element and creating a
new menu for it using the complete process described in this
section.</dd>
<dt>Any other node</dt>
<dd><span>Ignore</span> the node.</dd>
</dl>
<p>Once all the nodes have been processed as described above, the
user agent must the post-process the menu as follows:</p>
<ol>
<li>Except for separators, any menu item with no label, or whose
label is the empty string, must be removed.</li>
<li>Any sequence of two or more separators in a row must be
collapsed to a single separator.</li>
<li>Any separator at the start or end of the menu must be
removed.</li>
</ol>
</div>
<h5><dfn>Context menus</dfn></h5>
<p>The <dfn title="attr-contextmenu"><code>contextmenu</code></dfn>
attribute gives the element's <span title="context menus">context
menu</span>. The value must be the ID of a <code>menu</code> element
in the DOM. <span class="impl">If the node that would be obtained by
the invoking the <code>getElementById()</code> method using the
attribute's value as the only argument is null or not a
<code>menu</code> element, then the element has no assigned context
menu. Otherwise, the element's assigned context menu is the element
so identified.</span></p>
<div class="impl">
<p>When an element's context menu is requested (e.g. by the user
right-clicking the element, or pressing a context menu key), the UA
must <span>fire a simple event</span> named <code
title="event-contextmenu">contextmenu</code> that bubbles and is
cancelable at the element for which the menu was requested.</p>
<p class="note">Typically, therefore, the firing of the <code
title="event-contextmenu">contextmenu</code> event will be the
default action of a <code title="mouseup">mouseup</code> or <code
title="event-keyup">keyup</code> event. The exact sequence of events
is UA-dependent, as it will vary based on platform conventions.</p>
<p>The default action of the <code
title="event-contextmenu">contextmenu</code> event depends on
whether the element or one of its ancestors has a context menu
assigned (using the <code
title="attr-contextmenu">contextmenu</code> attribute) or not. If
there is no context menu assigned, the default action must be for
the user agent to show its default context menu, if it has one.</p>
<p>If the element or one of its ancestors <em>does</em> have a
context menu assigned, then the user agent must <span>fire a simple
event</span> named <code title="event-show">show</code> at the
<code>menu</code> element of the context menu of the nearest
ancestor (including the element itself) with one assigned.</p>
<!-- v2: include modifier key information -->
<p>The default action of <em>this</em> event is that the user agent
must show a context menu <span title="building menus and
toolbars">built</span> from the <code>menu</code> element.</p>
<p>The user agent may also provide access to its default context
menu, if any, with the context menu shown. For example, it could
merge the menu items from the two menus together, or provide the
page's context menu as a submenu of the default menu.</p>
<p>If the user dismisses the menu without making a selection,
nothing in particular happens.</p>
<p>If the user selects a menu item that represents a <span
title="concept-command">command</span>, then the UA must invoke
that command's <span title="command-facet-Action">Action</span>.</p>
<p>Context menus must not, while being shown, reflect changes in the
DOM; they are constructed as the default action of the <code
title="event-show">show</code> event and must remain as constructed
until dismissed.</p>
<p>User agents may provide means for bypassing the context menu
processing model, ensuring that the user can always access the UA's
default context menus. For example, the user agent could handle
right-clicks that have the Shift key depressed in such a way that it
does not fire the <code title="event-contextmenu">contextmenu</code>
event and instead always shows the default context menu.</p>
<p>The <dfn title="dom-contextMenu"><code>contextMenu</code></dfn>
attribute must <span>reflect</span> the <code
title="attr-contextmenu">contextmenu</code> content attribute.</p>
</div>
<div class="example">
<p>Here is an example of a context menu for an input control:</p>
<pre><form name="npc">
<label>Character name: <input name=char type=text contextmenu=namemenu required></label>
<menu type=context id=namemenu>
<command label="Pick random name" onclick="document.forms.npc.elements.char.value = getRandomName()">
<command label="Prefill other fields based on name" onclick="prefillFields(document.forms.npc.elements.char.value)">
</menu>
</form></pre>
<p>This adds to items to the control's context menu, one called
"Pick random name", and one called "Prefill other fields based on
name". They invoke scripts that are not shown in the example
above.</p>
</div>
<div class="impl">
<h5><dfn>Toolbars</dfn></h5>
<p>When a <code>menu</code> element has a <code
title="attr-menu-type">type</code> attribute in the <span
title="toolbar state">toolbar</span> state, then the user agent
must <span title="building menus and toolbars">build</span> the
menu for that <code>menu</code> element, and use the result in the
rendering.</p>
<p>The user agent must reflect changes made to the
<code>menu</code>'s DOM, by immediately <span title="building menus
and toolbars">rebuilding</span> the menu.</p>
</div>
<h4 id="commands">Commands</h4>
<p>A <dfn title="concept-command">command</dfn> is the abstraction
behind menu items, buttons, and links.<!--v2COMMAND: Once a command
is defined, other parts of the interface can refer to the same
command, allowing many access points to a single feature to share
aspects such as the disabled state.--></p>
<p id="facets">Commands are defined to have the following
<dfn title="concept-facet">facets</dfn>:</p>
<dl>
<dt><dfn title="command-facet-Type">Type</dfn></dt>
<dd>The kind of command: "command", meaning it is a normal command;
"radio", meaning that triggering the command will, amongst other
things, set the <span title="command-facet-CheckedState">Checked
State</span> to true (and probably uncheck some other commands); or
"checkbox", meaning that triggering the command will, amongst other
things, toggle the value of the <span
title="command-facet-CheckedState">Checked State</span>.</dd>
<dt><dfn title="command-facet-ID">ID</dfn></dt>
<dd>The name of the command, for referring to the command from the
markup or from script. If a command has no ID, it is an
<dfn>anonymous command</dfn>.</dd>
<dt><dfn title="command-facet-Label">Label</dfn></dt>
<dd>The name of the command as seen by the user.</dd>
<dt><dfn title="command-facet-Hint">Hint</dfn></dt>
<dd>A helpful or descriptive string that can be shown to the
user.</dd>
<dt><dfn title="command-facet-Icon">Icon</dfn></dt>
<dd>An <span>absolute URL</span> identifying a graphical image that
represents the action. A command might not have an Icon.</dd> <!--
changing base URLs might change the icon -->
<dt><dfn title="command-facet-AccessKey">Access Key</dfn></dt>
<dd>A key combination selected by the user agent that triggers the
command. A command might not have an Access Key.</dd>
<dt><dfn title="command-facet-HiddenState">Hidden State</dfn></dt>
<dd>Whether the command is hidden or not (basically, whether it
should be shown in menus).</dd>
<dt><dfn title="command-facet-DisabledState">Disabled State</dfn></dt>
<dd>Whether the command is relevant and can be triggered or not.</dd>
<dt><dfn title="command-facet-CheckedState">Checked State</dfn></dt>
<dd>Whether the command is checked or not.</dd>
<dt><dfn title="command-facet-Action">Action</dfn></dt>
<dd>The actual effect that triggering the command will have. This
could be a scripted event handler, a <span>URL</span> to which to
<span>navigate</span>, or a form submission.</dd>
<!-- v2COMMAND
<dt><dfn title="command-facet-Triggers">Triggers</dfn></dt>
<dd>The list of elements that can trigger the command. The element
defining a command is always in the list of elements that can
trigger the command. For anonymous commands, only the element
defining the command is on the list, since other elements have no
way to refer to it.</dd>
-->
</dl>
<p>These facets are exposed on elements using the <dfn>command
API</dfn>:</p>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-command-ro-commandType">commandType</code></dt>
<dd>
<p>Exposes the <span title="command-facet-Type">Type</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-id">id</code></dt>
<dd>
<p>Exposes the <span title="command-facet-ID">ID</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-command-ro-label">label</code></dt>
<dd>
<p>Exposes the <span title="command-facet-Label">Label</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-title">title</code></dt>
<dd>
<p>Exposes the <span title="command-facet-Hint">Hint</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-command-ro-icon">icon</code></dt>
<dd>
<p>Exposes the <span title="command-facet-Icon">Icon</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-accessKeyLabel">accessKeyLabel</code></dt>
<dd>
<p>Exposes the <span title="command-facet-AccessKey">Access Key</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-hidden">hidden</code></dt>
<dd>
<p>Exposes the <span title="command-facet-HiddenState">Hidden State</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-command-ro-disabled">disabled</code></dt>
<dd>
<p>Exposes the <span title="command-facet-DisabledState">Disabled State</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-command-ro-checked">checked</code></dt>
<dd>
<p>Exposes the <span title="command-facet-CheckedState">Checked State</span> facet of the command.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-click">click</code>()</dt>
<dd>
<p>Triggers the <span title="command-facet-Action">Action</span> of the command.</p>
</dd>
<!--v2COMMAND
<dt><var title="">element</var> . <code title="dom-command-ro-triggers">triggers</code></dt>
<dd>
<p>Exposes the <span title="command-facet-Triggers">Triggers</span> facet of the command.</p>
</dd>
-->
</dl>
<div class="impl">
<p>The <dfn
title="dom-command-ro-commandType"><code>commandType</code></dfn>
attribute must return a string whose value is either "<code
title="">command</code>", "<code title="">radio</code>", or "<code
title="">checked</code>", depending on whether the <span
title="command-facet-Type">Type</span> of the command defined by the
element is "command", "radio", or "checked" respectively. If the
element does not define a command, it must return null.</p>
<p>The <dfn title="dom-command-ro-label"><code>label</code></dfn>
attribute must return the command's <span
title="command-facet-Label">Label</span>, or null if the element
does not define a command or does not specify a <span
title="command-facet-Label">Label</span>. This attribute will be
shadowed by the <code title="">label</code> IDL attribute on
<code>option</code> and <code>command</code> elements.</p>
<p>The <dfn title="dom-command-ro-icon"><code>icon</code></dfn>
attribute must return the <span>absolute URL</span> of the command's
<span title="command-facet-Icon">Icon</span>. If the element does
not specify an icon, or if the element does not define a command,
then the attribute must return null. This attribute will be shadowed
by the <code title="dom-command-icon">icon</code> IDL attribute on
<code>command</code> elements.</p>
<p>The <dfn
title="dom-command-ro-disabled"><code>disabled</code></dfn>
attribute must return true if the command's <span
title="command-facet-DisabledState">Disabled State</span> is that
the command is disabled, and false if the command is not
disabled. This attribute is not affected by the command's <span
title="command-facet-HiddenState">Hidden State</span>. If the
element does not define a command, the attribute must return
false. This attribute will be shadowed by the <code
title="">disabled</code> IDL attribute on <code>button</code>,
<code>input</code>, <code>option</code>, and <code>command</code>
elements.</p>
<p>The <dfn
title="dom-command-ro-checked"><code>checked</code></dfn> attribute
must return true if the command's <span
title="command-facet-CheckedState">Checked State</span> is that the
command is checked, and false if it is that the command is not
checked. If the element does not define a command, the attribute
must return false. This attribute will be shadowed by the <code
title="">checked</code> IDL attribute on <code>input</code> and
<code>command</code> elements.</p>
<!--v2COMMAND
<p>The <dfn
title="dom-command-ro-triggers"><code>triggers</code></dfn>
attribute must return a list containing the elements that can
trigger the command (the command's <span
title="command-facet-Triggers">Triggers</span>). The list must be
<span>live</span>. While the element does not define a command, the
list must be empty.</p>
-->
<p class="note">The <span title="command-facet-ID">ID</span> facet
is exposed by the <code title="dom-id">id</code> IDL attribute,
the <span title="command-facet-Hint">Hint</span> facet is exposed by
the <code title="dom-title">title</code> IDL attribute, the <span
title="command-facet-AccessKey">AccessKey</span> facet is exposed by
the <code title="dom-accessKeyLabel">accessKeyLabel</code> IDL
attribute, and the <span title="command-facet-HiddenState">Hidden
State</span> facet is exposed by the <code
title="dom-hidden">hidden</code> IDL attribute.</p>
</div>
<hr>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-commands">commands</code></dt>
<dd>
<p>Returns an <code>HTMLCollection</code> of the elements in the
<code>Document</code> that define commands and have IDs.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-document-commands"><code>commands</code></dfn> attribute
of the document's <code>HTMLDocument</code> interface must return an
<code>HTMLCollection</code> rooted at the <code>Document</code>
node, whose filter matches only elements that <span
title="concept-command">define commands</span> and have <span
title="command-facet-ID">IDs</span>.</p>
</div>
<hr>
<p>User agents may expose the <span
title="concept-command">commands</span> whose <span
title="command-facet-HiddenState">Hidden State</span> facet is false
(visible), e.g. in the user agent's menu bar. User agents are
encouraged to do this especially for commands that have <span
title="command-facet-AccessKey">Access Keys</span>, as a way to
advertise those keys to the user.</p>
<div class="impl">
<h5><dfn title="a-command">Using the <code>a</code> element to define a command</dfn></h5>
<p>An <code>a</code> element with an <code
title="attr-hyperlink-href">href</code> attribute <span
title="concept-command">defines a command</span>.</p>
<p>The <span title="command-facet-Type">Type</span> of the command
is "command".</p>
<p>The <span title="command-facet-ID">ID</span> of the command is
the value of the <code title="attr-id">id</code> attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an <span>anonymous command</span>.</p>
<p>The <span title="command-facet-Label">Label</span> of the command
is the string given by the element's <code>textContent</code> IDL
attribute.</p>
<p>The <span title="command-facet-Hint">Hint</span> of the command
is the value of the <code title="attr-title">title</code> attribute
of the element. If the attribute is not present, the <span
title="command-facet-Hint">Hint</span> is the empty string.</p>
<p>The <span title="command-facet-Icon">Icon</span> of the command
is the <span>absolute URL</span> obtained from <span title="resolve
a url">resolving</span> the value of the <code
title="attr-img-src">src</code> attribute of the first
<code>img</code> element descendant of the element, relative to that
element, if there is such an element and resolving its attribute is
successful. Otherwise, there is no <span
title="command-facet-Icon">Icon</span> for the command.</p>
<p>The <span title="command-facet-AccessKey">AccessKey</span> of the
command is the element's <span>assigned access key</span>, if
any.</p>
<p>The <span title="command-facet-HiddenState">Hidden State</span>
of the command is true (hidden) if the element has a <code
title="attr-hidden">hidden</code> attribute, and false
otherwise.</p>
<p>The <span title="command-facet-DisabledState">Disabled
State</span> facet of the command is always false. (The command is
always enabled.)</p>
<p>The <span title="command-facet-CheckedState">Checked State</span>
of the command is always false. (The command is never checked.)</p>
<p>The <span title="command-facet-Action">Action</span> of the
command is to <span title="fire a click event">fire a <code
title="event-click">click</code> event</span> at the element.</p>
<h5><dfn title="button-command">Using the <code>button</code> element to define a command</dfn></h5>
<p>A <code>button</code> element always <span
title="concept-command">defines a command</span>.</p>
<p>The <span title="command-facet-Type">Type</span>, <span
title="command-facet-ID">ID</span>, <span
title="command-facet-Label">Label</span>, <span
title="command-facet-Hint">Hint</span>, <span
title="command-facet-Icon">Icon</span>, <span
title="command-facet-AccessKey">Access Key</span>, <span
title="command-facet-HiddenState">Hidden State</span>, <span
title="command-facet-CheckedState">Checked State</span>, and <span
title="command-facet-Action">Action</span> facets of the command are
determined <span title="a-command">as for <code>a</code>
elements</span> (see the previous section).</p>
<p>The <span title="command-facet-DisabledState">Disabled
State</span> of the command mirrors the <span
title="concept-fe-disabled">disabled</span> state of the button.</p>
<h5><dfn title="input-command">Using the <code>input</code> element to define a command</dfn></h5>
<p>An <code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in one of the <span
title="attr-input-type-submit">Submit Button</span>, <span
title="attr-input-type-reset">Reset Button</span>, <span
title="attr-input-type-image">Image Button</span>, <span
title="attr-input-type-button">Button</span>, <span
title="attr-input-type-radio">Radio Button</span>, or <span
title="attr-input-type-checkbox">Checkbox</span> states <span
title="concept-command">defines a command</span>.</p>
<p>The <span title="command-facet-Type">Type</span> of the command
is "radio" if the <code title="attr-input-type">type</code>
attribute is in the <code title="attr-input-type-radio">Radio
Button</code> state, "checkbox" if the <code
title="attr-input-type">type</code> attribute is in the <code
title="attr-input-type-checkbox">Checkbox</code> state, and
"command" otherwise.</p>
<p>The <span title="command-facet-ID">ID</span> of the command is
the value of the <code title="attr-id">id</code> attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an <span>anonymous command</span>.</p>
<p>The <span title="command-facet-Label">Label</span> of the command
depends on the Type of the command:</p>
<p>If the <span title="command-facet-Type">Type</span> is "command",
then it is the string given by the <code
title="attr-input-value">value</code> attribute, if any, and a
UA-dependent, locale-dependent value that the UA uses to label the
button itself if the attribute is absent.</p>
<p>Otherwise, the <span title="command-facet-Type">Type</span> is
"radio" or "checkbox". If the element is a <span>labeled
control</span>, the <code>textContent</code> of the first
<code>label</code> element in <span>tree order</span> whose
<span>labeled control</span> is the element in question is the <span
title="command-facet-Label">Label</span> (in DOM terms, this is the
string given by <code><var
title="">element</var>.labels[0].textContent</code>). Otherwise,
the value of the <code title="attr-input-value">value</code>
attribute, if present, is the <span
title="command-facet-Label">Label</span>. Otherwise, the <span
title="command-facet-Label">Label</span> is the empty string.</p>
<p>The <span title="command-facet-Hint">Hint</span> of the command
is the value of the <code title="attr-title">title</code> attribute
of the <code>input</code> element. If the attribute is not present, the
<span title="command-facet-Hint">Hint</span> is the empty
string.</p>
<p>If the element's <code title="attr-input-type">type</code>
attribute is in the <span title="attr-input-type-image">Image
Button</span> state, and the element has a <code
title="attr-img-src">src</code> attribute, and that attribute's
value can be successfully <span title="resolve a
url">resolved</span> relative to the element, then the <span
title="command-facet-Icon">Icon</span> of the command is the
<span>absolute URL</span> obtained from resolving that attribute
that way. Otherwise, there is no <span
title="command-facet-Icon">Icon</span> for the command.</p>
<p>The <span title="command-facet-AccessKey">AccessKey</span> of the
command is the element's <span>assigned access key</span>, if
any.</p>
<p>The <span title="command-facet-HiddenState">Hidden State</span>
of the command is true (hidden) if the element has a <code
title="attr-hidden">hidden</code> attribute, and false
otherwise.</p>
<p>The <span title="command-facet-DisabledState">Disabled
State</span> of the command mirrors the <span
title="concept-fe-disabled">disabled</span> state of the
control.</p>
<p>The <span title="command-facet-CheckedState">Checked State</span>
of the command is true if the command is of <span
title="command-facet-Type">Type</span> "radio" or "checkbox" and the
element is <span title="concept-fe-checked">checked</span>
attribute, and false otherwise.</p>
<p>The <span title="command-facet-Action">Action</span> of the
command, if the element has a defined <span>activation
behavior</span>, is to <span>run synthetic click activation
steps</span> on the element. Otherwise, it is just to <span>fire a
<code title="event-click">click</code> event</span> at the
element.</p>
<h5><dfn title="option-command">Using the <code>option</code> element to define a command</dfn></h5>
<p>An <code>option</code> element with an ancestor
<code>select</code> element and either no <code
title="attr-option-value">value</code> attribute or a <code
title="attr-option-value">value</code> attribute that is not the
empty string <span title="concept-command">defines a
command</span>.</p>
<p>The <span title="command-facet-Type">Type</span> of the command
is "radio" if the <code>option</code>'s nearest ancestor
<code>select</code> element has no <code
title="attr-select-multiple">multiple</code> attribute, and
"checkbox" if it does.</p>
<p>The <span title="command-facet-ID">ID</span> of the command is
the value of the <code title="attr-id">id</code> attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an <span>anonymous command</span>.</p>
<p>The <span title="command-facet-Label">Label</span> of the command
is the value of the <code>option</code> element's <code
title="attr-option-label">label</code> attribute, if there is one,
or the value of the <code>option</code> element's
<code>textContent</code> IDL attribute if there isn't.</p>
<p>The <span title="command-facet-Hint">Hint</span> of the command
is the string given by the element's <code
title="attr-title">title</code> attribute, if any, and the empty
string if the attribute is absent.</p>
<p>There is no <span title="command-facet-Icon">Icon</span> for the
command.</p>
<p>The <span title="command-facet-AccessKey">AccessKey</span> of the
command is the element's <span>assigned access key</span>, if
any.</p>
<p>The <span title="command-facet-HiddenState">Hidden State</span>
of the command is true (hidden) if the element has a <code
title="attr-hidden">hidden</code> attribute, and false
otherwise.</p>
<p>The <span title="command-facet-DisabledState">Disabled
State</span> of the command is true (disabled) if the element is
<span title="concept-option-disabled">disabled</span> or if its
nearest ancestor <code>select</code> element is <span
title="concept-option-disabled">disabled</span>, and false
otherwise.</p>
<p>The <span title="command-facet-CheckedState">Checked State</span>
of the command is true (checked) if the element's <span
title="concept-option-selectedness">selectedness</span> is true, and
false otherwise.</p>
<p>The <span title="command-facet-Action">Action</span> of the
command depends on its <span
title="command-facet-Type">Type</span>. If the command is of <span
title="command-facet-Type">Type</span> "radio" then it must <span
title="concept-select-pick">pick</span> the <code>option</code>
element. Otherwise, it must <span
title="concept-select-toggle">toggle</span> the <code>option</code>
element.</p>
<h5>Using the <dfn
title="command-element"><code>command</code></dfn> element to define
a command</h5>
<p>A <code>command</code> element <span
title="concept-command">defines a command</span>.</p>
<p>The <span title="command-facet-Type">Type</span> of the command
is "radio" if the <code>command</code>'s <code
title="attr-command-type">type</code> attribute is
"<code>radio</code>", "checkbox" if the attribute's value is
"<code>checkbox</code>", and "command" otherwise.</p>
<p>The <span title="command-facet-ID">ID</span> of the command is
the value of the <code title="attr-id">id</code> attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an <span>anonymous command</span>.</p>
<p>The <span title="command-facet-Label">Label</span> of the command
is the value of the element's <code
title="attr-command-label">label</code> attribute, if there is one,
or the empty string if it doesn't.</p>
<p>The <span title="command-facet-Hint">Hint</span> of the command
is the string given by the element's <code
title="attr-command-title">title</code> attribute, if any, and the
empty string if the attribute is absent.</p>
<p>The <span title="command-facet-Icon">Icon</span> for the command
is the <span>absolute URL</span> obtained from <span title="resolve
a url">resolving</span> the value of the element's <code
title="attr-command-icon">icon</code> attribute, relative to the
element, if it has such an attribute and resolving it is
successful. Otherwise, there is no <span
title="command-facet-Icon">Icon</span> for the command.</p>
<p>The <span title="command-facet-AccessKey">AccessKey</span> of the
command is the element's <span>assigned access key</span>, if
any.</p>
<p>The <span title="command-facet-HiddenState">Hidden State</span>
of the command is true (hidden) if the element has a <code
title="attr-hidden">hidden</code> attribute, and false
otherwise.</p>
<p>The <span title="command-facet-DisabledState">Disabled
State</span> of the command is true (disabled) if the element has a
<code title="attr-command-disabled">disabled</code> attribute, and
false otherwise.</p>
<p>The <span title="command-facet-CheckedState">Checked State</span>
of the command is true (checked) if the element has a <code
title="attr-command-checked">checked</code> attribute, and false
otherwise.</p>
<p>The <span title="command-facet-Action">Action</span> of the
command, if the element has a defined <span>activation
behavior</span>, is to <span>run synthetic click activation
steps</span> on the element. Otherwise, it is just to <span>fire a
<code title="event-click">click</code> event</span> at the
element.</p>
<h5><dfn title="label-command">Using the <code title="attr-accesskey">accesskey</code> attribute on a <code>label</code> element to define a command</dfn></h5>
<p>A <code>label</code> element that has an <span>assigned access
key</span> and a <span>labeled control</span> and whose
<span>labeled control</span> <span title="concept-command">defines a
command</span>, itself <span title="concept-command">defines a
command</span>.</p>
<p>The <span title="command-facet-Type">Type</span> of the command
is "command".</p>
<p>The <span title="command-facet-ID">ID</span> of the command is
the value of the <code title="attr-id">id</code> attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an <span>anonymous command</span>.</p>
<p>The <span title="command-facet-Label">Label</span> of the command
is the string given by the element's <code>textContent</code> IDL
attribute.</p>
<p>The <span title="command-facet-Hint">Hint</span> of the command
is the value of the <code title="attr-title">title</code> attribute
of the element.</p>
<p>There is no <span title="command-facet-Icon">Icon</span> for the
command.</p>
<p>The <span title="command-facet-AccessKey">AccessKey</span> of the
command is the element's <span>assigned access key</span>.</p>
<p>The <span title="command-facet-HiddenState">Hidden State</span>,
<span title="command-facet-DisabledState">Disabled State</span>, and
<span title="command-facet-Action">Action</span> facets of the
command are the same as the respective facets of the element's
<span>labeled control</span>.</p>
<p>The <span title="command-facet-CheckedState">Checked State</span>
of the command is always false. (The command is never checked.)</p>
<h5><dfn title="legend-command">Using the <code title="attr-accesskey">accesskey</code> attribute on a <code>legend</code> element to define a command</dfn></h5>
<p>A <code>legend</code> element that has an <span>assigned access
key</span> and is a child of a <code>fieldset</code> element that
has a descendant that is not a descendant of the <code>legend</code>
element and is neither a <code>label</code> element nor a
<code>legend</code> element but that <span
title="concept-command">defines a command</span>, itself <span
title="concept-command">defines a command</span>.</p>
<p>The <span title="command-facet-Type">Type</span> of the command
is "command".</p>
<p>The <span title="command-facet-ID">ID</span> of the command is
the value of the <code title="attr-id">id</code> attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an <span>anonymous command</span>.</p>
<p>The <span title="command-facet-Label">Label</span> of the command
is the string given by the element's <code>textContent</code> IDL
attribute.</p>
<p>The <span title="command-facet-Hint">Hint</span> of the command
is the value of the <code title="attr-title">title</code> attribute
of the element.</p>
<p>There is no <span title="command-facet-Icon">Icon</span> for the
command.</p>
<p>The <span title="command-facet-AccessKey">AccessKey</span> of the
command is the element's <span>assigned access key</span>.</p>
<p>The <span title="command-facet-HiddenState">Hidden State</span>,
<span title="command-facet-DisabledState">Disabled State</span>, and
<span title="command-facet-Action">Action</span> facets of the
command are the same as the respective facets of the first element
in <span>tree order</span> that is a descendant of the parent of the
<code>legend</code> element that <span
title="concept-command">defines a command</span> but is not a
descendant of the <code>legend</code> element and is neither a
<code>label</code> nor a <code>legend</code> element.</p>
<p>The <span title="command-facet-CheckedState">Checked State</span>
of the command is always false. (The command is never checked.)</p>
<h5><dfn title="accesskey-command">Using the <code title="attr-accesskey">accesskey</code> attribute to define a command on other elements</dfn></h5>
<p>An element that has an <span>assigned access key</span> <span
title="concept-command">defines a command</span>.</p>
<p>If one of the other sections that define elements that <span
title="concept-command">define commands</span> define that this
element <span title="concept-command">defines a command</span>, then
that section applies to this element, and this section does
not. Otherwise, this section applies to that element.</p>
<p>The <span title="command-facet-Type">Type</span> of the command
is "command".</p>
<p>The <span title="command-facet-ID">ID</span> of the command is
the value of the <code title="attr-id">id</code> attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an <span>anonymous command</span>.</p>
<p>The <span title="command-facet-Label">Label</span> of the command
depends on the element. If the element is a <span>labeled
control</span>, the <code>textContent</code> of the first
<code>label</code> element in <span>tree order</span> whose
<span>labeled control</span> is the element in question is the <span
title="command-facet-Label">Label</span> (in DOM terms, this is the
string given by <code><var
title="">element</var>.labels[0].textContent</code>). Otherwise, the
<span title="command-facet-Label">Label</span> is the
<code>textContent</code> of the element itself.</p>
<p>The <span title="command-facet-Hint">Hint</span> of the command
is the value of the <code title="attr-title">title</code> attribute
of the element. If the attribute is not present, the <span
title="command-facet-Hint">Hint</span> is the empty string.</p>
<p>There is no <span title="command-facet-Icon">Icon</span> for the
command.</p>
<p>The <span title="command-facet-AccessKey">AccessKey</span> of the
command is the element's <span>assigned access key</span>.</p>
<p>The <span title="command-facet-HiddenState">Hidden State</span>
of the command is true (hidden) if the element has a <code
title="attr-hidden">hidden</code> attribute, and false
otherwise.</p>
<p>The <span title="command-facet-DisabledState">Disabled
State</span> facet of the command is always false. (The command is
always enabled.)</p>
<p>The <span title="command-facet-CheckedState">Checked State</span>
of the command is always false. (The command is never checked.)</p>
<p>The <span title="command-facet-Action">Action</span> of the
command is to run the following steps:</p>
<ol>
<li>If the element is <span>focusable</span>, run the
<span>focusing steps</span> for the element.</li>
<li>If the element has a defined <span>activation behavior</span>,
<span>run synthetic click activation steps</span> on the
element.</li>
<li>Otherwise, if the element does not have a defined
<span>activation behavior</span>, <span>fire a <code
title="event-click">click</code> event</span> at the element.</li>
</ol>
</div>
<h3>Common idioms without dedicated elements</h3>
<h4>Tag clouds</h4>
<p id="tag-cloud">This specification does not define any markup
specifically for marking up lists of keywords that apply to a group
of pages (also known as <i>tag clouds</i>). In general, authors are
encouraged to either mark up such lists using <code>ul</code>
elements with explicit inline counts that are then hidden and turned
into a presentational effect using a style sheet, or to use SVG.</p>
<div class="example">
<p>Here, three tags are included in a short tag cloud:</p>
<pre><style>
@media screen, print, handheld, tv {
/* should be ignored by non-visual browsers */
.tag-cloud > li > span { display: none; }
.tag-cloud > li { display: inline; }
.tag-cloud-1 { font-size: 0.7em; }
.tag-cloud-2 { font-size: 0.9em; }
.tag-cloud-3 { font-size: 1.1em; }
.tag-cloud-4 { font-size: 1.3em; }
.tag-cloud-5 { font-size: 1.5em; }
}
</style>
...
<ul class="tag-cloud">
<li class="tag-cloud-4"><a title="28 instances" href="/t/apple">apple</a> <span>(popular)</span>
<li class="tag-cloud-2"><a title="6 instances" href="/t/kiwi">kiwi</a> <span>(rare)</span>
<li class="tag-cloud-5"><a title="41 instances" href="/t/pear">pear</a> <span>(very popular)</span>
</ul></pre>
<p>The actual frequency of each tag is given using the <code
title="attr-title">title</code> attribute. A CSS style sheet is
provided to convert the markup into a cloud of differently-sized
words, but for user agents that do not support CSS or are not
visual, the markup contains annotations like "(popular)" or
"(rare)" to categorize the various tags by frequency, thus enabling
all users to benefit from the information.</p>
<p>The <code>ul</code> element is used (rather than
<code>ol</code>) because the order is not particular important:
while the list is in fact ordered alphabetically, it would convey
the same information if ordered by, say, the length of the tag.</p>
<p>The <code title="rel-tag">tag</code> <code
title="attr-hyperlink-rel">rel</code>-keyword is <em>not</em> used
on these <code>a</code> elements because they do not represent tags
that apply to the page itself; they are just part of an index
listing the tags themselves.</p>
</div>
<h4>Conversations</h4>
<!-- http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-September/022576.html -->
<p>This specification does not define a specific element for marking
up conversations, meeting minutes, chat transcripts, dialogues in
screenplays, instant message logs, and other situations where
different players take turns in discourse.</p>
<p>Instead, authors are encouraged to mark up conversations using
<code>p</code> elements and punctuation. Authors who need to mark
the speaker for styling purposes are encouraged to use
<code>span</code> or <code>b</code>. Paragraphs with their text
wrapped in the <code>i</code> element can be used for marking up
stage directions.</p>
<div class="example">
<p>This example demonstrates this using an extract from Abbot and
Costello's famous sketch, <cite>Who's on first</cite>:</p>
<pre><p> Costello: Look, you gotta first baseman?
<p> Abbott: Certainly.
<p> Costello: Who's playing first?
<p> Abbott: That's right.
<p> Costello becomes exasperated.
<p> Costello: When you pay off the first baseman every month, who gets the money?
<p> Abbott: Every dollar of it.</pre>
</div>
<div class="example">
<p>The following extract shows how an IM conversation log could be
marked up.</p>
<pre><p> <time>14:22</time> <b>egof</b> I'm not that nerdy, I've only seen 30% of the star trek episodes
<p> <time>14:23</time> <b>kaj</b> if you know what percentage of the star trek episodes you have seen, you are inarguably nerdy
<p> <time>14:23</time> <b>egof</b> it's unarguably
<p> <time>14:23</time> <i>* kaj blinks</i>
<p> <time>14:24</time> <b>kaj</b> you are not helping your case</pre>
<!-- with thanks to http://bash.org/?854262 -->
</div>
<h4 id="footnotes">Footnotes</h4>
<p>HTML does not have a dedicated mechanism for marking up
footnotes. Here are the recommended alternatives.</p>
<hr>
<p>For short inline annotations, the <code
title="attr-title">title</code> attribute should be used.</p>
<div class="example">
<p>In this example, two parts of a dialogue are annotated with
footnote-like content using the <code
title="attr-title">title</code> attribute.</p>
<pre><p> <b>Customer</b>: Hello! I wish to register a complaint. Hello. Miss?
<p> <b>Shopkeeper</b>: <strong><span title="Colloquial pronunciation of 'What do you'"</strong>
>Watcha</span> mean, miss?
<p> <b>Customer</b>: Uh, I'm sorry, I have a cold. I wish to make a complaint.
<p> <b>Shopkeeper</b>: Sorry, <span <strong>title="This is, of course, a lie."</strong>>we're
closing for lunch</span>.</pre>
</div>
<hr>
<p>For longer annotations, the <code>a</code> element should be
used, pointing to an element later in the document. The convention
is that the contents of the link be a number in square brackets.</p>
<div class="example">
<p>In this example, a footnote in the dialogue links to a paragraph
below the dialogue. The paragraph then reciprocally links back to the
dialogue, allowing the user to return to the location of the
footnote.</p>
<pre><p> Announcer: Number 16: The <i>hand</i>.
<p> Interviewer: Good evening. I have with me in the studio tonight
Mr Norman St John Polevaulter, who for the past few years has been
contradicting people. Mr Polevaulter, why <em>do</em> you
contradict people?
<p> Norman: I don't. <sup><a href="#fn1" id="r1">[1]</a></sup>
<p> Interviewer: You told me you did!
<em>...</em>
<section>
<p id="fn1"><a href="#r1">[1]</a> This is, naturally, a lie,
but paradoxically if it were true he could not say so without
contradicting the interviewer and thus making it false.</p>
</section></pre>
</div>
<hr>
<p>For side notes, longer annotations that apply to entire sections
of the text rather than just specific words or sentences, the
<code>aside</code> element should be used.</p>
<div class="example">
<p>In this example, a sidebar is given after a dialogue, giving it
some context.</p>
<pre><p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched.
<p> <span class="speaker">Shopkeeper</span>: I'm sorry?
<p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched.
<p> <span class="speaker">Shopkeeper</span>: No no no, this's'a tobacconist's.
<aside>
<p>In 1970, the British Empire lay in ruins, and foreign
nationalists frequented the streets — many of them Hungarians
(not the streets — the foreign nationals). Sadly, Alexander
Yalt has been publishing incompetently-written phrase books.
</aside></pre>
</div>
<hr>
<p>For figures or tables, footnotes can be included in the relevant
<code>dt</code> or <code>caption</code> element, or in surrounding
prose.</p>
<div class="example">
<p>In this example, a <!-- round --> table has cells with footnotes
that are given in prose. A <code>figure</code> element is used to
give a single legend to the combination of the table and its
footnotes.</p>
<pre><figure>
<dt>Table 1. Alternative activities for knights.</dt>
<dd>
<table>
<tr>
<th> Activity
<th> Location
<th> Cost
<tr>
<td> Dance
<td> Wherever possible
<td> £0<sup><a href="#fn1">1</a></sup>
<tr>
<td> Routines, chorus scenes<sup><a href="#fn2">2</a></sup>
<td> Undisclosed
<td> Undisclosed
<tr>
<td> Dining<sup><a href="#fn3">3</a></sup>
<td> Camelot
<td> Cost of ham, jam, and spam<sup><a href="#fn4">4</a></sup>
</table>
<p id="fn1">1. Assumed.</p>
<p id="fn2">2. Footwork impeccable.</p>
<p id="fn3">3. Quality described as "well".</p>
<p id="fn4">4. A lot.</p>
</dd>
</figure></pre>
</div>
<div class="impl">
<h3>Matching HTML elements using selectors</h3>
<p>There are a number of dynamic selectors that can be used with
HTML. This section defines when these selectors match HTML
elements.</p>
<dl>
<dt><dfn title="selector-link"><code>:link</code></dfn></dt>
<dt><dfn title="selector-visited"><code>:visited</code></dfn></dt>
<dd>
<p>All <code>a</code> elements that have an <code
title="attr-hyperlink-href">href</code> attribute, all
<code>area</code> elements that have an <code
title="attr-hyperlink-href">href</code> attribute, and all
<code>link</code> elements that have an <code
title="attr-link-href">href</code> attribute, must match one of
<code title="selector-link">:link</code> and <code
title="selector-visited">:visited</code>.</p>
</dd>
<dt><dfn title="selector-active"><code>:active</code></dfn></dt>
<dd>
<p>The <code title="selector-active">:active</code> pseudo-class
must match the following elements between the time the user begins
to activate the element and the time the user stops activating
the element:</p>
<ul>
<li><code>a</code> elements that have an <code
title="attr-hyperlink-href">href</code> attribute</li>
<li><code>area</code> elements that have an <code
title="attr-hyperlink-href">href</code> attribute</li>
<li><code>link</code> elements that have an <code
title="attr-link-href">href</code> attribute</li>
<li><code>button</code> elements that are not <span
title="concept-fe-disabled">disabled</span></li>
<li><code>input</code> elements whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-submit">Submit Button</span>, <span
title="attr-input-type-image">Image Button</span>, <span
title="attr-input-type-reset">Reset Button</span>, or <span
title="attr-input-type-button">Button</span> state</li>
<li><code>command</code> elements that do not have a <code
title="attr-command-disabled">disabled</code> attribute</li>
<li>any other element, if it is <span>specially
focusable</span></li>
</ul>
<p class="example">For example, if the user is using a keyboard to
push a <code>button</code> element by pressing the space bar, the
element would match this pseudo-class in between the time that the
element received the <code title="event-keydown">keydown</code>
event and the time the element received the <code
title="event-keyup">keyup</code> event.</p>
</dd>
<dt><dfn title="selector-enabled"><code>:enabled</code></dfn></dt>
<dd>
<p>The <code title="selector-enabled">:enabled</code> pseudo-class
must match the following elements:</p>
<ul>
<li><code>a</code> elements that have an <code
title="attr-hyperlink-href">href</code> attribute</li>
<li><code>area</code> elements that have an <code
title="attr-hyperlink-href">href</code> attribute</li>
<li><code>link</code> elements that have an <code
title="attr-link-href">href</code> attribute</li>
<li><code>button</code> elements that are not <span
title="concept-fe-disabled">disabled</span></li>
<li><code>input</code> elements whose <code
title="attr-input-type">type</code> attribute are not in the
<span title="attr-input-type-hidden">Hidden</span> state and that
are not <span title="concept-fe-disabled">disabled</span></li>
<li><code>select</code> elements that are not <span
title="concept-fe-disabled">disabled</span></li>
<li><code>textarea</code> elements that are not <span
title="concept-fe-disabled">disabled</span></li>
<li><code>option</code> elements that do not have a <code
title="attr-option-disabled">disabled</code> attribute</li>
<li><code>command</code> elements that do not have a <code
title="attr-command-disabled">disabled</code> attribute</li>
<li><code>li</code> elements that are children of
<code>menu</code> elements, and that have a child element that
defines a <span title="concept-command">command</span>, if the
first such element's <span
title="command-facet-disabledstate">Disabled State</span> facet
is false (not disabled)</li>
</ul>
</dd>
<dt><dfn title="selector-disabled"><code>:disabled</code></dfn></dt>
<dd>
<p>The <code title="selector-disabled">:disabled</code>
pseudo-class must match the following elements:</p>
<ul>
<li><code>button</code> elements that are <span
title="concept-fe-disabled">disabled</span></li>
<li><code>input</code> elements whose <code
title="attr-input-type">type</code> attribute are not in the
<span title="attr-input-type-hidden">Hidden</span> state and that
are <span title="concept-fe-disabled">disabled</span></li>
<li><code>select</code> elements that are <span
title="concept-fe-disabled">disabled</span></li>
<li><code>textarea</code> elements that are <span
title="concept-fe-disabled">disabled</span></li>
<li><code>option</code> elements that have a <code
title="attr-option-disabled">disabled</code> attribute</li>
<li><code>command</code> elements that have a <code
title="attr-command-disabled">disabled</code> attribute</li>
<li><code>li</code> elements that are children of
<code>menu</code> elements, and that have a child element that
defines a <span title="concept-command">command</span>, if the
first such element's <span
title="command-facet-disabledstate">Disabled State</span> facet
is true (disabled)</li>
</ul>
</dd>
<dt><dfn title="selector-checked"><code>:checked</code></dfn></dt>
<dd>
<p>The <code title="selector-checked">:checked</code> pseudo-class
must match the following elements:</p>
<ul>
<li><code>input</code> elements whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-checkbox">Checkbox</span> state and whose
<span title="concept-fe-checked">checkedness</span> state is
true</li>
<li><code>input</code> elements whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-radio">Radio Button</span> state and whose
<span title="concept-fe-checked">checkedness</span> state is
true</li>
<li><code>command</code> elements whose <code
title="attr-command-type">type</code> attribute is in the <span
title="attr-command-type-state-checkbox">Checkbox</span> state
and that have a <code title="attr-command-checked">checked</code>
attribute</li>
<li><code>command</code> elements whose <code
title="attr-command-type">type</code> attribute is in the <span
title="attr-command-type-state-radio">Radio</span> state and that
have a <code title="attr-command-checked">checked</code>
attribute</li>
</ul>
</dd>
<dt><dfn title="selector-indeterminate"><code>:indeterminate</code></dfn></dt>
<dd>
<p>The <code title="selector-indeterminate">:indeterminate</code>
pseudo-class must match <code>input</code> elements whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-checkbox">Checkbox</span> state and whose
<code title="dom-input-indeterminate">indeterminate</code> IDL
attribute is set to true.</p>
</dd>
<dt><dfn title="selector-default"><code>:default</code></dfn></dt>
<dd>
<p>The <code title="selector-default">:default</code> pseudo-class
must match the following elements:</p>
<ul>
<li><code>button</code> elements that are their form's
<span>default button</span></li>
<li><code>input</code> elements whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-submit">Submit Button</span> or <span
title="attr-input-type-image">Image Button</span> state, and that
are their form's <span>default button</span></li>
<!--
<li><code>command</code> elements that have a <code
title="attr-command-default">default</code> attribute</li>
-->
</ul>
</dd>
<dt><dfn title="selector-valid"><code>:valid</code></dfn></dt>
<dd>
<p>The <code title="selector-valid">:valid</code> pseudo-class
must match all elements that are <span title="candidate for
constraint validation">candidates for constraint validation</span>
and that <span title="concept-fv-valid">satisfy their
constraints</span>.</p>
</dd>
<dt><dfn title="selector-invalid"><code>:invalid</code></dfn></dt>
<dd>
<p>The <code title="selector-invalid">:invalid</code> pseudo-class
must match all elements that are <span title="candidate for
constraint validation">candidates for constraint validation</span>
but that do not <span title="concept-fv-valid">satisfy their
constraints</span>.</p>
</dd>
<dt><dfn title="selector-in-range"><code>:in-range</code></dfn></dt>
<dd>
<p>The <code title="selector-in-range">:in-range</code>
pseudo-class must match all elements that are <span
title="candidate for constraint validation">candidates for
constraint validation</span> and that are neither <span>suffering
from an underflow</span> nor <span>suffering from an
overflow</span>.</p>
</dd>
<dt><dfn title="selector-out-of-range"><code>:out-of-range</code></dfn></dt>
<dd>
<p>The <code title="selector-out-of-range">:out-of-range</code>
pseudo-class must match all elements that are <span
title="candidate for constraint validation">candidates for
constraint validation</span> and that are <span>suffering from an
underflow</span> or <span>suffering from an overflow</span>.</p>
</dd>
<dt><dfn title="selector-required"><code>:required</code></dfn></dt>
<dd>
<p>The <code title="selector-required">:required</code>
pseudo-class must match the following elements:</p>
<ul>
<li><code>input</code> elements that are <i
title="concept-input-required">required</i></li>
<li><code>textarea</code> elements that have a <code
title="attr-textarea-required">required</code>
attribute</li>
</ul>
</dd>
<dt><dfn title="selector-optional"><code>:optional</code></dfn></dt>
<dd>
<p>The <code title="selector-optional">:optional</code>
pseudo-class must match the following elements:</p>
<ul>
<li><code>button</code> elements</li>
<li><code>input</code> elements that are not <i
title="concept-input-required">required</i></li>
<li><code>select</code> elements</li>
<li><code>textarea</code> elements that do not have a <code
title="attr-textarea-required">required</code>
attribute</li>
</ul>
</dd>
<dt><dfn title="selector-read-only"><code>:read-only</code></dfn></dt>
<dt><dfn title="selector-read-write"><code>:read-write</code></dfn></dt>
<dd>
<p>The <code title="selector-read-write">:read-write</code>
pseudo-class must match the following elements:</p>
<ul>
<li><code>input</code> elements to which the <code
title="attr-input-readonly">readonly</code> attribute applies,
but that are not <i title="concept-input-immutable">immutable</i>
(i.e. that do not have the <code
title="attr-input-readonly">readonly</code> attribute specified
and that are not <span
title="concept-fe-disabled">disabled</span>)</li>
<li><code>textarea</code> elements that do not have a <code
title="attr-textarea-readonly">readonly</code> attribute, and
that are not <span
title="concept-fe-disabled">disabled</span></li>
<li>any element that is <span>editable</span></li>
</ul>
<p>The <code title="selector-read-only">:read-only</code>
pseudo-class must match all other <span>HTML elements</span>.</p>
</dd>
</dl>
<p class="note">Another section of this specification defines the
<i>target element</i> used with the <code
title="selector-target">:target</code> pseudo-class.</p>
<p class="note">This specification does not define when an element
matches the <code title="selector-hover">:hover</code>, <code
title="selector-focus">:focus</code>, or <code
title="selector-lang()">:lang()</code> dynamic pseudo-classes, as
those are all defined in sufficient detail in a language-agnostic
fashion in the Selectors specification. <a
href="#refsSELECTORS">[SELECTORS]</a></p>
</div>
<h2 id="microdata"><dfn>Microdata</dfn></h2>
<!-- v2
* <itemref itemprop="foo" src="url#id"> to import the item with
id="id" from url into the current microdata block as the value of
property foo?
* splitting the 'content' part of a property into multiple sub-bits,
as in:
<span itemprop="tel" item-content-in-bits>
Telephone:
<span content-bit>+44</span> (0) <span content-bit>1223 123 123</span>
</span>
maybe vocabs that need this can use a sub vocabulary specifically
for this:
<span itemprop="tel" itemscope itemtype="http://bits.example/">
Telephone:
<span itemprop=bit>+44</span> (0) <span itemprop=bit>1223 123 123</span>
</span>
-->
<h3>Introduction</h3>
<h4>Overview</h4>
<p><i>This section is non-normative.</i></p>
<p>Sometimes, it is desirable to annotate content with specific
machine-readable labels, e.g. to allow generic scripts to provide
services that are customised to the page, or to enable content from
a variety of cooperating authors to be processed by a single script
in a consistent manner.</p>
<p>For this purpose, authors can use the microdata features
described in this section. Microdata allows nested groups of
name-value pairs to be added to documents, in parallel with the
existing content.</p>
<!--START html--><!--START html5-->
<h4>The basic syntax</h4>
<p><i>This section is non-normative.</i></p>
<p>At a high level, microdata consists of a group of name-value
pairs. The groups are called <span
title="concept-item">items</span>, and each name-value pair is a
property. Items and properties are represented by regular
elements.</p>
<p>To create an item, the <code
title="attr-itemscope">itemscope</code> attribute is used.</p>
<p>To add a property to an item, the <code
title="attr-itemprop">itemprop</code> attribute is used on one of
the <span title="concept-item">item's</span> descendants.</p>
<div class="example">
<p>Here there are two items, each of which has the property "name":</p>
<pre><div itemscope>
<p>My name is <span itemprop="name">Elizabeth</span>.</p>
</div>
<div itemscope>
<p>My name is <span itemprop="name">Daniel</span>.</p>
</div></pre>
</div>
<p>Properties generally have values that are strings.</p>
<div class="example">
<p>Here the item has three properties:</p>
<pre><div itemscope>
<p>My name is <span itemprop="name">Neil</span>.</p>
<p>My band is called <span itemprop="band">Four Parts Water</span>.</p>
<p>I am <span itemprop="nationality">British</span>.</p>
</div></pre>
</div>
<p>Properties can also have values that are <span
title="URL">URLs</span>. This is achieved using the <code>a</code>
element and its <code title="attr-hyperlink-href">href</code>
attribute, the <code>img</code> element and its <code
title="attr-img-src">src</code> attribute, or other elements that
link to or embed external resources.</p>
<div class="example">
<p>In this example, the item has one property, "image", whose value
is a URL:</p>
<pre><div itemscope>
<img itemprop="image" src="google-logo.png" alt="Google">
</div></pre>
</div>
<p>Properties can also have values that are dates, times, or dates
and times. This is achieved using the <code>time</code> element and
its <code title="attr-time-datetime">datetime</code> attribute.</p>
<div class="example">
<p>In this example, the item has one property,
"birthday", whose value is a date:</p>
<pre><div itemscope>
I was born on <time itemprop="birthday" datetime="2009-05-10">May 10th 2009</time>.
</div></pre>
</div>
<p>Properties can also themselves be groups of name-value pairs, by
putting the <code title="attr-itemscope">itemscope</code> attribute
on the element that declares the property.</p>
<p>Items that are not part of others are called <span>top-level
microdata items</span>.</p>
<div class="example">
<p>In this example, the outer item represents a person, and the
inner one represents a band:</p>
<pre><div itemscope>
<p>Name: <span itemprop="name">Amanda</span></p>
<p>Band: <span itemprop="band" itemscope> <span itemprop="name">Jazz Band</span> (<span itemprop="size">12</span> players)</span></p>
</div></pre>
<p>The outer item here has two properties, "name" and
"band". The "name" is "Amanda", and the
"band" is an item in its own right, with two
properties, "name" and "size". The
"name" of the band is "Jazz Band", and the
"size" is "12".</p>
<p>The outer item in this example is a top-level microdata
item.</p>
</div>
<p>Properties that are not descendants of the element with the <code
title="attr-itemscope">itemscope</code> attribute can be associated
with the <span title="concept-item">item</span> using the <code
title="attr-itemref">itemref</code> attribute. This attribute takes
a list of IDs of elements to crawl in addition to crawling the
children of the element with the <code
title="attr-itemscope">itemscope</code> attribute.</p>
<div class="example">
<p>This example is the same as the previous one, but all the
properties are separated from their <span
title="concept-item">items</span>:</p>
<pre><div itemscope id="amanda" itemref="a b"></div>
<p id="a">Name: <span itemprop="name">Amanda</span></p>
<div id="b" itemprop="band" itemscope itemref="c"></div>
<div id="c">
<p>Band: <span itemprop="name">Jazz Band</span></p>
<p>Size: <span itemprop="size">12</span> players</p>
</div></pre>
<p>This gives the same result as the previous example. The first
item has two properties, "name", set to "Amanda", and "band", set
to another item. That second item has two further properties,
"name", set to "Jazz Band", and "size", set to "12".</p>
</div>
<p>An <span title="concept-item">item</span> can have multiple
properties with the same name and different values.</p>
<div class="example">
<p>This example describes an ice cream, with two flavors:</p>
<pre><div itemscope>
<p>Flavors in my favorite ice cream:</p>
<ul>
<li itemprop="flavor">Lemon sorbet</li>
<li itemprop="flavor">Apricot sorbet</li>
</ul>
</div></pre>
<p>This thus results in an item with two properties, both
"flavor", having the values "Lemon sorbet" and "Apricot
sorbet".</p>
</div>
<p>An element introducing a property can also introduce multiple
properties at once, to avoid duplication when some of the properties
have the same value.</p>
<div class="example">
<p>Here we see an item with two properties,
"favorite-color" and "favorite-fruit", both
set to the value "orange":</p>
<pre><div itemscope>
<span itemprop="favorite-color favorite-fruit">orange</span>
</div></pre>
</div>
<p>It's important to note that there is no relationship between the
microdata and the content of the document where the microdata is
marked up.</p>
<div class="example">
<p>There is no semantic difference, for instance, between the
following two examples:</p>
<pre><figure>
<dd><img src="castle.jpeg">
<dt><span itemscope><span itemprop="name">The Castle</span></span> (1986)
</figure></pre>
<pre><span itemscope><meta itemprop="name" content="The Castle"></span>
<figure>
<dd><img src="castle.jpeg">
<dt>The Castle (1986)
</figure></pre>
<p>Both have a figure with a caption, and both, completely
unrelated to the figure, have an item with a name-value pair with
the name "name" and the value "The Castle". The only
difference is that if the user drags the caption out of the
document, in the former case, the item will be included in the
drag-and-drop data. In neither case is the image in any way
associated with the item.</p>
</div>
<h4>Typed items</h4>
<p><i>This section is non-normative.</i></p>
<p>The examples in the previous section show how information could
be marked up on a page that doesn't expect its microdata to be
re-used. Microdata is most useful, though, when it is used in
contexts where other authors and readers are able to cooperate to
make new uses of the markup.</p>
<p>For this purpose, it is necessary to give each <span
title="concept-item">item</span> a type, such as
"http://example.com/person", or "http://example.org/cat", or
"http://band.example.net/". Types are identified as <span
title="URL">URLs</span>.</p>
<p>The type for an <span title="concept-item">item</span> is given
as the value of an <code title="attr-itemtype">itemtype</code>
attribute on the same element as the <code
title="attr-itemscope">itemscope</code> attribute.</p>
<div class="example">
<p>Here, the item is "http://example.org/animals#cat":</p>
<pre><section itemscope itemtype="http://example.org/animals#cat">
<h1 itemprop="name">Hedral</h1>
<p itemprop="desc">Hedral is a male american domestic
shorthair, with a fluffy black fur with white paws and belly.</p>
<img itemprop="img" src="hedral.jpeg" alt="" title="Hedral, age 18 months">
</section></pre>
<p>In this example the "http://example.org/animals#cat" item has three
properties, a "name" ("Hedral"), a "desc" ("Hedral is..."), and an
"img" ("hedral.jpeg").</p>
</div>
<p>An item can only have one type. The type gives the context for
the properties, thus defining a vocabulary: a property named "class"
given for an item with the type "http://census.example/person" might
refer to the economic class of an individual, while a property named
"class" given for an item with the type "http://example.com/school/teacher"
might refer to the classroom a teacher has been assigned.</p>
<h4>Global identifiers for items</h4>
<p><i>This section is non-normative.</i></p>
<p>Sometimes, an <span title="concept-item">item</span> gives
information about a topic that has a global identifier. For example,
books can be identified by their ISBN number.</p>
<p>Vocabularies (as identified by the <code
title="attr-itemtype">itemtype</code> attribute) can be designed
such that <span title="concept-item">items</span> get associated
with their global identifier in an unambiguous way by expressing the
global identifiers as <span title="URL">URLs</span> given in an
<code title="attr-itemid">itemid</code> attribute.</p>
<p>The exact meaning of the <span title="URL">URLs</span> given in
<code title="attr-itemid">itemid</code> attributes depends on the
vocabulary used.</p>
<div class="example">
<p>Here, an item is talking about a particular book:</p>
<pre><dl itemscope
itemtype="http://vocab.example.net/book"
<strong>itemid="urn:isbn:0-330-34032-8"</strong>>
<dt>Title
<dd itemprop="title">The Reality Dysfunction
<dt>Author
<dd itemprop="author">Peter F. Hamilton
<dt>Publication date
<dd><time itemprop="pubdate" datetime="1996-01-26">26 January 1996</time>
</dl></pre>
<p>The "<code title="">http://vocab.example.net/book</code>"
vocabulary in this example would define that the <code
title="attr-itemid">itemid</code> attribute takes a <code
title="">urn:</code> <span>URL</span> pointing to the ISBN of the
book.</p>
</div>
<!-- (commented out since itemtype="" defines the meaning of the
identifier for now)
<p>Although it is common practice, authors are encouraged not to use
the same URL to identify multiple topics; in particular, an HTTP URL
usually identifies a specific resource (such as an image or
document), and authors are encouraged to not use them to identify
people, non-Web resources like companies, movies, and products, or
other abstract concepts. Using an HTTP URL as a global identifier
for something other than the resource actually designated by the URL
leads to a situation where it is ambiguous whether the identifier,
and thus the set of properties specified in the microdata,
references the page or something else.</p>
-->
<h4>Selecting names when defining vocabularies</h4>
<p><i>This section is non-normative.</i></p>
<p>Using microdata means using a vocabulary. For some purposes, an
ad-hoc vocabulary is adequate. For others, a vocabulary will need to
be designed. Where possible, authors are encouraged to re-use
existing vocabularies, as this makes content re-use easier.</p>
<p>When designing new vocabularies, identifiers can be created
either using <span title="URL">URLs</span>, or, for properties, as
plain words (with no dots or colons). For URLs, conflicts with other
vocabularies can be avoided by only using identifiers that
correspond to pages that the author has control over.</p>
<div class="example">
<p>For instance, if Jon and Adam both write content at <code
title="">example.com</code>, at <code
title="">http://example.com/~jon/...</code> and <code
title="">http://example.com/~adam/...</code> respectively, then
they could select identifiers of the form
"http://example.com/~jon/name" and "http://example.com/~adam/name"
respectively.</p>
</div>
<p>Properties whose names are just plain words can only be used
within the context of the types for which they are intended;
properties named using URLs can be reused in items of any type. If
an item has no type, and is not part of another item, then if its
properties have names that are just plain words, they are not
intended to be globally unique, and are instead only intended for
limited use. Generally speaking, authors are encouraged to use
either properties with globally unique names (URLs) or ensure that
their items are typed.</p>
<div class="example">
<p>Here, an item is an "http://example.org/animals#cat", and most of the
properties have names that are words defined in the context of that
type. There are also a few additional properties whose names come
from other vocabularies.</p>
<pre><section itemscope itemtype="http://example.org/animals#cat">
<h1 itemprop="name http://example.com/fn">Hedral</h1>
<p itemprop="desc">Hedral is a male american domestic
shorthair, with a fluffy <span
itemprop="http://example.com/color">black</span> fur with <span
itemprop="http://example.com/color">white</span> paws and belly.</p>
<img itemprop="img" src="hedral.jpeg" alt="" title="Hedral, age 18 months">
</section></pre>
<p>This example has one item with the type "http://example.org/animals#cat"
and the following properties:</p>
<table>
<thead>
<tr>
<td>Property
<td>Value
<tbody>
<tr>
<td>name
<td>Hedral
<tr>
<td>http://example.com/fn
<td>Hedral
<tr>
<td>desc
<td>Hedral is a male american domestic shorthair, with a fluffy black fur with white paws and belly.
<tr>
<td>http://example.com/color
<td>black
<tr>
<td>http://example.com/color
<td>white
<tr>
<td>img
<td>.../hedral.jpeg
</table>
</div>
<h4>Using the microdata DOM API</h4>
<p><i>This section is non-normative.</i></p>
<p>The microdata becomes even more useful when scripts can use it to
expose information to the user, for example offering it in a form
that can be used by other applications.</p>
<p>The <code title="dom-document-getItems">document.getItems(<var
title="">typeNames</var>)</code> method provides access to the
<span>top-level microdata items</span>. It returns a
<code>NodeList</code> containing the items with the specified types,
or all types if no argument is specified.</p>
<p>Each <span title="concept-item">item</span> is represented in the
DOM by the element on which the relevant <code
title="attr-itemscope">itemscope</code> attribute is found. These
elements have their <code
title="dom-itemScope">element.itemScope</code> IDL attribute set to
true.</p>
<p>The type of <span title="concept-item">items</span> can be
obtained using the <code
title="dom-itemType">element.itemType</code> IDL attribute on the
element with the <code title="attr-itemscope">itemscope</code>
attribute.</p>
<div class="example">
<p>This sample shows how the <code
title="dom-document-getItems">getItems()</code> method can be used
to obtain a list of all the top-level microdata items of one type
given in the document:</p>
<pre>var cats = document.getItems("http://example.com/feline");</pre>
</div>
<p>Once an element representing an <span
title="concept-item">item</span> has been obtained, its properties
can be extracted using the <code
title="dom-properties">properties</code> IDL attribute. This
attribute returns an <code>HTMLPropertiesCollection</code>, which can
be enumerated to go through each element that adds one or more
properties to the item. It can also be indexed by name, which will
return an object with a list of the elements that add properties
with that name.</p>
<p>Each element that adds a property also has a <code
title="dom-itemValue">itemValue</code> IDL attribute that returns
its value.</p>
<div class="example">
<p>This sample gets the first item of type "http://example.net/user" and
then pops up an alert using the "name" property from
that item.</p>
<pre>var user = document.getItems('http://example.net/user')[0];
alert('Hello ' + user.properties['name'][0].content + '!');</pre>
</div>
<p>The <code>HTMLPropertiesCollection</code> object, when indexed by
name in this way, actually returns a <code>PropertyNodeList</code>
object with all the matching properties. The
<code>PropertyNodeList</code> object can be used to obtained all the
values at once using <em>its</em> <code
title="dom-PropertyNodeList-values">values</code> attribute, which
returns an array of all the values.</p>
<div class="example">
<p>In an earlier example, a "http://example.org/animals#cat" item had two
"http://example.com/color" values. This script looks up the first such
item and then lists all its values.</p>
<pre>var cat = document.getItems('http://example.com/animals#cat')[0];
var colors = cat.properties['http://example.com/color'].values;
var result;
if (colors.length == 0) {
result = 'Color unknown.';
} else if (colors.length == 1) {
result = 'Color: ' + colors[0];
} else {
result = 'Colors:';
for (var i = 0; i < colors.length; i += 1)
result += ' ' + colors[i];
}</pre>
</div>
<p>It's also possible to get a list of all the <span>property
names</span> using the object's <code
title="dom-HTMLPropertiesCollection-names">names</code> IDL
attribute.</p>
<div class="example">
<p>This example creates a big list with a nested list for each item
on the page, each with of all the property names used in that
item.</p>
<pre>var outer = document.createElement('ul');
var items = document.getItems();
for (var item = 0; item < items.length; item += 1) {
var itemLi = document.createElement('li');
var inner = document.createElement('ul');
for (var name = 0; name < items[item].properties.names.length; name += 1) {
var propLi = document.createElement('li');
propLi.appendChild(document.createTextNode(items[item].properties.names[name]));
inner.appendChild(propLi);
}
itemLi.appendChild(inner);
outer.appendChild(itemLi);
}
document.body.appendChild(outer);</pre>
<p>If faced with the following from an earlier example:</p>
<pre><section itemscope itemtype="http://example.org/animals#cat">
<h1 itemprop="name http://example.com/fn">Hedral</h1>
<p itemprop="desc">Hedral is a male american domestic
shorthair, with a fluffy <span
itemprop="http://example.com/color">black</span> fur with <span
itemprop="http://example.com/color">white</span> paws and belly.</p>
<img itemprop="img" src="hedral.jpeg" alt="" title="Hedral, age 18 months">
</section></pre>
<p>...it would result in the following output:</p>
<ul>
<li>
<ul>
<li>name</li>
<li>http://example.com/fn</li>
<li>desc</li>
<li>http://example.com/color</li>
<li>img</li>
</ul>
</li>
</ul>
<p>(The duplicate occurrence of "http://example.com/color" is not included
in the list.)</p>
</div>
<h3>Encoding microdata</h3>
<h4>The microdata model</h4>
<p>The microdata model consists of groups of name-value pairs known
as <span title="concept-item">items</span>.</p>
<p>Each group is known as an <span
title="concept-item">item</span>. Each <span
title="concept-item">item</span> can have an <span>item type</span>,
a <span>global identifier</span> (if the <span>item type</span>
<span title="support global identifiers for items">supports global
identifiers for its items</span>), and a list of name-value
pairs. Each name in the name-value pair is known as a <span
title="the properties of an item">property</span>, and each <span
title="the properties of an item">property</span> has one or more
<span title="concept-property-value">values</span>. Each <span title="concept-property-value">value</span> is either a string or itself a group of
name-value pairs (an <span title="concept-item">item</span>).</p>
<p>An <span title="concept-item">item</span> is said to be a
<dfn>typed item</dfn> when either it has an <span>item type</span>,
or it is the <span title="concept-property-value">value</span> of a <span title="the properties of an
item">property</span> of a <span>typed item</span>. The
<dfn>relevant type</dfn> for a <span>typed item</span> is the <span
title="concept-item">item</span>'s <span>item type</span>, if it has
one, or else is the <span>relevant type</span> of the <span
title="concept-item">item</span> for which it is a <span title="the
properties of an item">property</span>'s <span title="concept-property-value">value</span>.</p>
<h4>Items</h4>
<p>Every <span title="HTML elements">HTML element</span> may have an
<dfn title="attr-itemscope"><code>itemscope</code></dfn> attribute
specified. The <code title="attr-itemscope">itemscope</code>
attribute is a <span>boolean attribute</span>.</p>
<p>An element with the <code title="attr-itemscope">itemscope</code>
attribute specified creates a new <dfn
title="concept-item">item</dfn>, a group of name-value pairs.</p>
<hr>
<p>Elements with an <code title="attr-itemscope">itemscope</code>
attribute may have an <dfn
title="attr-itemtype"><code>itemtype</code></dfn> attribute
specified, to give the <span>item type</span> of the <span
title="concept-item">item</span>.</p>
<p>The <code title="attr-itemtype">itemtype</code> attribute, if
specified, must have a value that is a <span>valid URL</span> that
is an <span>absolute URL</span> for which the string "<code
title="">http://www.w3.org/1999/xhtml/microdata#</code>" is not a
<span>prefix match</span>.</p> <!-- we disallow that prefix so that
we have somewhere to put future extensions, e.g. if we ever support
short type names -->
<p>The <dfn>item type</dfn> of an <span
title="concept-item">item</span> is the value of its element's <code
title="attr-itemtype">itemtype</code> attribute, if it has one and
its value is not the empty string. If the <code
title="attr-itemtype">itemtype</code> attribute is missing or its
value is the empty string, the <span
title="concept-item">item</span> is said to have no <span>item
type</span>.</p>
<p>The <span>item type</span> must be a type defined in an <span
title="other applicable specifications">applicable
specification</span>.</p>
<p>The <code title="attr-itemtype">itemtype</code> attribute must
not be specified on elements that do not have an <code
title="attr-itemscope">itemscope</code> attribute specified.</p>
<hr>
<p>Elements with an <code title="attr-itemscope">itemscope</code>
attribute and an <code title="attr-itemtype">itemtype</code>
attribute that references a vocabulary that is defined to
<dfn>support global identifiers for items</dfn> may also have an
<dfn title="attr-itemid"><code>itemid</code></dfn> attribute
specified, to give a global identifier for the <span
title="concept-item">item</span>, so that it can be related to other
<span title="concept-item">items</span> on pages elsewhere on the
Web.</p>
<p>The <code title="attr-itemid">itemid</code> attribute, if
specified, must have a value that is a <span>valid URL</span>.</p>
<p>The <dfn>global identifier</dfn> of an <span
title="concept-item">item</span> is the value of its element's <code
title="attr-itemid">itemid</code> attribute, if it has one, <span
title="resolve a url">resolved</span> relative to the element on
which the attribute is specified. If the <code
title="attr-itemid">itemid</code> attribute is missing or if
resolving it fails, it is said to have no <span>global
identifier</span>.</p>
<p>The <code title="attr-itemid">itemid</code> attribute must not be
specified on elements that do not have both an <code
title="attr-itemscope">itemscope</code> attribute and an <code
title="attr-itemtype">itemtype</code> attribute specified, and must
not be specified on elements with an <code
title="attr-itemscope">itemscope</code> attribute whose <code
title="attr-itemtype">itemtype</code> attribute specifies a
vocabulary that does not <span>support global identifiers for
items</span>, as defined by that vocabulary's specification.</p>
<hr>
<p>Elements with an <code title="attr-itemscope">itemscope</code>
attribute may have an <dfn
title="attr-itemref"><code>itemref</code></dfn> attribute specified,
to give a list of additional elements to crawl to find the
name-value pairs of the <span title="concept-item">item</span>.</p>
<p>The <code title="attr-itemref">itemref</code> attribute, if
specified, must have a value that is an <span>unordered set of
unique space-separated tokens</span> consisting of <span
title="concept-ID">IDs</span> of elements in the same document; for
each one, the element's nearest ancestor element with an <code
title="attr-itemscope">itemscope</code> attribute specified, if any,
must not be the element with the referencing <code
title="attr-itemref">itemref</code> attribute specified.</p>
<p>The <code title="attr-itemref">itemref</code> attribute must not
be specified on elements that do not have an <code
title="attr-itemscope">itemscope</code> attribute specified.</p>
<h4>Names: the <dfn title="attr-itemprop"><code>itemprop</code></dfn> attribute</h4>
<p>Every <span title="HTML elements">HTML element</span> may have an
<code title="attr-itemprop">itemprop</code> attribute specified, if
doing so <span title="the properties of an item">adds a
property</span> to one or more <span
title="concept-item">items</span> (as defined below).</p>
<p>The <code title="attr-itemprop">itemprop</code> attribute, if
specified, must have a value that is an <span>unordered set of
unique space-separated tokens</span> representing the names of the
name-value pairs that it adds. The attribute's value must have at
least one token.</p>
<p>Each token must be either:</p>
<ul>
<li>A <span>valid URL</span> that is an <span>absolute URL</span>
for which the string "<code
title="">http://www.w3.org/1999/xhtml/microdata#</code>" is not a
<span>prefix match</span>, or</li>
<li>If the item is a <span>typed item</span>: a <dfn>defined
property name</dfn> allowed in this situation according to the
specification that defines the <span>relevant type</span> for the
item, or</li>
<li>If the item is not a <span>typed item</span>: a string that
contains no U+002E FULL STOP characters (.) and no U+003A COLON
characters (:).</li>
</ul>
<p>When an element with an <code
title="concept-itemprop">itemprop</code> attribute <span title="the
properties of an item">adds a property</span> to multiple <span
title="concept-item">items</span>, the requirement above regarding
the tokens applies for each <span title="concept-item">item</span>
individually.</p>
<!--
e.g.:
<div itemscope itemtype="http://example.com/a"> <ref refid="x"> </div>
<div itemscope itemtype="http://example.com/b"> <ref refid="x"> </div>
<meta id="x" itemprop="z" content="">
"z" had better be valid for both http://example.com/a and http://example.com/b
-->
<p>The <dfn>property names</dfn> of an element are the tokens that
the element's <code title="attr-itemprop">itemprop</code> attribute
is found to contain when its value is <span title="split a string on
spaces">split on spaces</span>, with the order preserved but with
duplicates removed (leaving only the first occurrence of each
name).</p>
<p>Within an <span title="concept-item">item</span>, the properties
are unordered with respect to each other, except for properties with
the same name, which are ordered in the order they are given by the
algorithm that defines <span>the properties of an item</span>.</p>
<div class="example">
<p>In the following example, the "a" property has the values "1"
and "2", <em>in that order</em>, but whether the "a" property comes
before the "b" property or not is not important:</p>
<pre><div itemscope>
<p itemprop="a">1</p>
<p itemprop="a">2</p>
<p itemprop="b">test</p>
</div></pre>
<p>Thus, the following is equivalent:</p>
<pre><div itemscope>
<p itemprop="b">test</p>
<p itemprop="a">1</p>
<p itemprop="a">2</p>
</div></pre>
<p>As is the following:</p>
<pre><div itemscope>
<p itemprop="a">1</p>
<p itemprop="b">test</p>
<p itemprop="a">2</p>
</div></pre>
<p>And the following:</p>
<pre><div itemscope itemref="x">
<p itemprop="b">test</p>
<p itemprop="a">2</p>
</div>
<div id="x">
<p itemprop="a">1</p>
</div>
</pre>
</div>
<h4>Values</h4>
<p>The <dfn title="concept-property-value">property value</dfn> of a
name-value pair added by an element with an <code
title="attr-itemprop">itemprop</code> attribute depends on the
element, as follows:</p>
<dl>
<dt>If the element also has an <code
title="attr-itemscope">itemscope</code> attribute</dt>
<dd><p>The value is the <span title="concept-item">item</span>
created by the element.</p></dd>
<dt>If the element is a <code>meta</code> element</dt>
<dd><p>The value is the value of the element's <code
title="attr-content">content</code> attribute, if any, or the empty
string if there is no such attribute.</p></dd>
<dt>If the element is an <code>audio</code>, <code>embed</code>,
<code>iframe</code>, <code>img</code>, <code>source</code>, or
<code>video</code> element</dt>
<dd><p>The value is the <span>absolute URL</span> that results from
<span title="resolve a url">resolving</span> the value of the
element's <code title="">src</code> attribute relative to the
element at the time the attribute is set, or the empty string if
there is no such attribute or if <span title="resolve a
url">resolving</span> it results in an error.</p></dd>
<dt>If the element is an <code>a</code>, <code>area</code>, or
<code>link</code> element</dt>
<dd><p>The value is the <span>absolute URL</span> that results from
<span title="resolve a url">resolving</span> the value of the
element's <code title="">href</code> attribute relative to the
element at the time the attribute is set, or the empty string if
there is no such attribute or if <span title="resolve a
url">resolving</span> it results in an error.</p></dd>
<dt>If the element is an <code>object</code> element</dt>
<dd><p>The value is the <span>absolute URL</span> that results from
<span title="resolve a url">resolving</span> the value of the
element's <code title="">data</code> attribute relative to the
element at the time the attribute is set, or the empty string if
there is no such attribute or if <span title="resolve a
url">resolving</span> it results in an error.</p></dd>
<dt>If the element is a <code>time</code> element with a <code
title="attr-datetime">datetime</code> attribute</dt>
<dd><p>The value is the value of the element's <code
title="attr-datetime">datetime</code> attribute.</p></dd>
<dt>Otherwise</dt>
<dd><p>The value is the element's
<code>textContent</code>.</p></dd>
</dl>
<p>The <dfn>URL property elements</dfn> are the <code>a</code>,
<code>area</code>, <code>audio</code>, <code>embed</code>,
<code>iframe</code>, <code>img</code>, <code>link</code>,
<code>object</code>, <code>source</code>, and <code>video</code>
elements.</p>
<p>If a property's <span title="concept-property-value">value</span>
is an <span>absolute URL</span>, the property must be specified
using an <span title="URL property elements">URL property
element</span>.</p>
<h4>Associating names with items</h4>
<p>To find <dfn>the properties of an item</dfn>, the user agent must
run the following steps:</p>
<ol>
<li><p>Let <var title="">root</var> be the element with the <code
title="attr-itemscope">itemscope</code> attribute.</p></li>
<li><p>Let <var title="">pending</var> be a stack of elements
initially containing the child elements of <var
title="">root</var>, if any, in <span>tree order</span> (so that
the first child element of <var title="">root</var> will be the
first one to be popped from the stack). This list will be the one
that holds the elements that still need to be crawled.</p></li>
<li><p>Let <var title="">properties</var> be an empty list of
elements. This list will be the result of the algorithm: a list of
elements with properties that apply to <var
title="">root</var>.</p></li>
<li><p>If <var title="">root</var> has an <code
title="attr-itemref">itemref</code> attribute, <span title="split a
string on spaces">split the value of that <code
title="attr-itemref">itemref</code> attribute on spaces</span>. For
each resulting token, <var title="">ID</var>, if there is an
element in the document with the <span title="concept-ID">ID</span>
<var title="">ID</var>, then push the first such element onto <var
title="">pending</var>.</p></li>
<li>
<p>For each element <var title="">candidate</var> in <var
title="">pending</var>, run the following substeps:</p>
<ol>
<li><p>Let <var title="">scope</var> be <var
title="">candidate</var>'s nearest ancestor element with an <code
title="attr-itemscope">itemscope</code> attribute
specified.</p></li>
<li><p>If one of the other elements in <var title="">pending</var>
is also <var title="">candidate</var>, then remove <var
title="">candidate</var> from <var title="">pending</var>
(i.e. remove duplicates).</p></li>
<li><p>Otherwise, if one of the other elements in <var
title="">pending</var> is an ancestor element of <var
title="">candidate</var>, and that element is <var
title="">scope</var>, then remove <var title="">candidate</var>
from <var title="">pending</var>.</p></li>
<li><p>Otherwise, if one of the other elements in <var
title="">pending</var> is an ancestor element of <var
title="">candidate</var>, and that element also has <var
title="">scope</var> as its nearest ancestor element with an
<code title="attr-itemscope">itemscope</code> attribute
specified, then remove <var title="">candidate</var> from <var
title="">pending</var>.</p></li>
</ol>
</li>
<li><p>Sort <var title="">pending</var> in <span>tree
order</span>.</p></li>
<li><p><i>Loop</i>: Pop the top element from <var
title="">pending</var> and let <var title="">current</var> be that
element.</p></li>
<li><p>If <var title="">current</var> has an <code
title="attr-itemprop">itemprop</code> attribute, then append <var
title="">current</var> to <var title="">properties</var>.</p></li>
<li><p>If <var title="">current</var> does not have an <code
title="attr-itemscope">itemscope</code> attribute, and <var
title="">current</var> is an element with child elements, then:
push all the child elements of <var title="">current</var> onto
<var title="">pending</var>, in <span>tree order</span> (so the first
child of <var title="">current</var> will be the next element to be
popped from <var title="">pending</var>).</p></li>
<li><p><i>End of loop</i>: If <var title="">pending</var> is not
empty, return to the step marked <i>loop</i>.</p></li>
<li><p>Return <var title="">properties</var>. That is the list of
<span title="the properties of an item">properties of the
item</span> <var title="">root</var>. By definition, this list is
in <span>tree order</span>.</p></li>
</ol>
<p>A document must not contain any elements that have an <code
title="attr-itemprop">itemprop</code> attribute that would not be
found to be a property of any of the <span
title="concept-item">items</span> in that document were their <span
title="the properties of an item">properties</span> all to be
determined.</p>
<p>An <span title="concept-item">item</span> is a <dfn
title="top-level microdata items">top-level microdata item</dfn> if
its element does not have an <code
title="attr-itemprop">itemprop</code> attribute.</p>
<h4>Examples</h4>
<p>Here is an example of some HTML using Microdata to express RDF
statements:</p>
<pre><dl itemscope
itemtype="http://purl.org/vocab/frbr/core#Work"
itemid="http://purl.oreilly.com/works/45U8QJGZSQKDH8N">
<dt>Title</dt>
<dd><cite itemprop="http://purl.org/dc/terms/title">Just a Geek</cite></dd>
<dt>By</dt>
<dd><span itemprop="http://purl.org/dc/terms/creator">Wil Wheaton</span></dd>
<dt>Format</dt>
<dd itemprop="http://purl.org/vocab/frbr/core#realization"
itemscope
itemtype="http://purl.org/vocab/frbr/core#Expression"
itemid="http://purl.oreilly.com/products/9780596007683.BOOK">
<link itemprop="http://purl.org/dc/terms/type" href="http://purl.oreilly.com/product-types/BOOK">
Print
</dd>
<dd itemprop="http://purl.org/vocab/frbr/core#realization"
itemscope
itemtype="http://purl.org/vocab/frbr/core#Expression"
itemid="http://purl.oreilly.com/products/9780596802189.EBOOK">
<link itemprop="http://purl.org/dc/terms/type" href="http://purl.oreilly.com/product-types/EBOOK">
Ebook
</dd>
</dl></pre>
<p>This is equivalent to the following Turtle:</p>
<pre>@prefix dc: <http://purl.org/dc/terms/> .
@prefix frbr: <http://purl.org/vocab/frbr/core#> .
<http://purl.oreilly.com/works/45U8QJGZSQKDH8N> a frbr:Work ;
dc:creator "Wil Wheaton"@en ;
dc:title "Just a Geek"@en ;
frbr:realization <http://purl.oreilly.com/products/9780596007683.BOOK>,
<http://purl.oreilly.com/products/9780596802189.EBOOK> .
<http://purl.oreilly.com/products/9780596007683.BOOK> a frbr:Expression ;
dc:type <http://purl.oreilly.com/product-types/BOOK> .
<http://purl.oreilly.com/products/9780596802189.EBOOK> a frbr:Expression ;
dc:type <http://purl.oreilly.com/product-types/EBOOK> .</pre>
<h3>Microdata DOM API</h3>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-getItems">getItems</code>( [ <var title="">types</var> ] )</dt>
<dd>
<p>Returns a <code>NodeList</code> of the elements in the <code>Document</code> that create <span title="concept-item">items</span>, that are not part of other <span title="concept-item">items</span>, and that are of one of the types given in the argument, if any are listed.</p>
<p>The <var title="">types</var> argument is interpreted as a space-separated list of types.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-properties">properties</code></dt>
<dd>
<p>If the element has an <code
title="attr-itemscope">itemscope</code> attribute, returns an
<code>HTMLPropertiesCollection</code> object with all the element's
properties. Otherwise, an empty
<code>HTMLPropertiesCollection</code> object.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-itemValue">itemValue</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the element's <span
title="concept-property-value">value</span>.</p>
<p>Can be set, to change the element's <span
title="concept-property-value">value</span>. Setting the <span
title="concept-property-value">value</span> when the element has
no <code title="attr-itemprop">itemprop</code> attribute or when
the element's value is an <span title="concept-item">item</span>
throws an <code>INVALID_ACCESS_ERR</code> exception.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-document-getItems"><code>document.getItems(<var
title="">typeNames</var>)</code></dfn> method takes an optional
string that contains an <span>unordered set of unique
space-separated tokens</span> representing types. When called, the
method must return a live <code>NodeList</code> object containing
all the elements in the document, in <span>tree order</span>, that
are each <span>top-level microdata items</span> with a <span
title="item type">type</span> equal to one of the types specified in
that argument, having obtained the types by <span title="split a
string on spaces">splitting the string on spaces</span>. If there
are no tokens specified in the argument, or if the argument is
missing, then the method must return a <code>NodeList</code>
containing all the <span>top-level microdata items</span> in the
document.</p>
<p>The <dfn title="dom-itemScope"><code>itemScope</code></dfn> IDL
attribute on <span>HTML elements</span> must <span>reflect</span>
the <code title="attr-itemscope">itemscope</code> content attribute.
The <dfn title="dom-itemType"><code>itemType</code></dfn> IDL
attribute on <span>HTML elements</span> must <span>reflect</span>
the <code title="attr-itemtype">itemtype</code> content attribute.
The <dfn title="dom-itemId"><code>itemId</code></dfn> IDL attribute
on <span>HTML elements</span> must <span>reflect</span> the <code
title="attr-itemid">itemid</code> content attribute. The <dfn
title="dom-itemProp"><code>itemProp</code></dfn> IDL attribute on
<span>HTML elements</span> must <span>reflect</span> the <code
title="attr-itemprop">itemprop</code> content attribute. The <dfn
title="dom-itemRef"><code>itemRef</code></dfn> IDL attribute on
<span>HTML elements</span> must <span>reflect</span> the <code
title="attr-itemref">itemref</code> content attribute.</p>
<p>The <dfn title="dom-properties"><code>properties</code></dfn> IDL
attribute on <span>HTML elements</span> must return an
<code>HTMLPropertiesCollection</code> rooted at the
<code>Document</code> node, whose filter matches only elements that
have <span>property names</span> and are <span title="the properties
of an item">the properties of the item</span> created by the element
on which the attribute was invoked, while that element is an <span
title="concept-item">item</span>, and matches nothing the rest of
the time.</p>
<p>The <dfn title="dom-itemValue"><code>itemValue</code></dfn> IDL
attribute's behavior depends on the element, as follows:</p>
<dl>
<dt>If the element has no <code title="attr-itemprop">itemprop</code> attribute</dt>
<dd><p>The attribute must return null on getting and must throw an
<code>INVALID_ACCESS_ERR</code> exception on setting.</p>
<dt>If the element has an <code title="attr-itemscope">itemscope</code> attribute</dt>
<dd><p>The attribute must return the element itself on getting and
must throw an <code>INVALID_ACCESS_ERR</code> exception on
setting.</p>
<dt>If the element is a <code>meta</code> element</dt>
<dd><p>The attribute must act as it would if it was <span
title="reflect">reflecting</span> the element's <code
title="attr-meta-content">content</code> content
attribute.</p></dd>
<dt>If the element is an <code>audio</code>, <code>embed</code>,
<code>iframe</code>, <code>img</code>, <code>source</code>, or
<code>video</code> element</dt>
<dd><p>The attribute must act as it would if it was <span
title="reflect">reflecting</span> the element's <code
title="">src</code> content attribute.</p></dd>
<dt>If the element is an <code>a</code>, <code>area</code>, or
<code>link</code> element</dt>
<dd><p>The attribute must act as it would if it was <span
title="reflect">reflecting</span> the element's <code
title="">href</code> content attribute.</p></dd>
<dt>If the element is an <code>object</code> element</dt>
<dd><p>The attribute must act as it would if it was <span
title="reflect">reflecting</span> the element's <code
title="">data</code> content attribute.</p></dd>
<dt>If the element is a <code>time</code> element with a <code
title="attr-datetime">datetime</code> attribute</dt>
<dd><p>The attribute must act as it would if it was <span
title="reflect">reflecting</span> the element's <code
title="">datetime</code> content attribute.</p></dd>
<dt>Otherwise</dt>
<dd><p>The attribute must act the same as the element's
<code>textContent</code> attribute.</p></dd>
</dl>
<p>When the <code title="dom-itemValue">itemValue</code> IDL
attribute is <span title="reflect">reflecting</span> a content
attribute or acting like the element's <code>textContent</code>
attribute, the user agent must, on setting, convert the new value to
the IDL <code title="">DOMString</code> value before using it
according to the mappings described above.</p>
</div>
<!--END html--><!--END html5-->
<h3>Microdata vocabularies</h3>
<!--START vocabs--><!--END complete-->
<h3 class="no-num no-toc">Table of contents</h3>
<!--toc-->
<hr>
<h4>Introduction</h4>
<p>This specification defines microdata vocabularies.
<a href="#refsHTML5">[HTML5]</a></p>
<!--START complete-->
<h4>vCard</h4>
<!--END vocabs--><!--END complete-->
<!--START vCard-->
<h4 class="no-num no-toc">Table of contents</h4>
<!--toc-->
<hr>
<h5>The vocabulary</h5>
<p>This section defines a microdata vocabulary. <a
href="#refsHTML5">[HTML5]</a></p>
<!--START vocabs--><!--START complete-->
<p>An item with the <span>item type</span> <dfn
title="md-vcard"><code>http://microformats.org/profile/hcard</code></dfn>
represents a person's or organization's contact information.</p>
<p>This vocabulary <span title="support global identifiers for
items">supports global identifiers for items</span>.</p>
<p>The following are the type's <span title="defined property
name">defined property names</span>. They are based on the
vocabulary defined in the vCard specification and its extensions,
where more information on how to interpret the values can be
found. <a href="#refsRFC2426">[RFC2426]</a> <a
href="#refsRFC4770">[RFC4770]</a></p>
<dl>
<dt><dfn title="md-vcard-fn"><code>fn</code></dfn></dt>
<dd>
<p>Gives the formatted text corresponding to the name of the
person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Exactly one property with the name <code
title="md-vcard-fn">fn</code> must be present within each <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-n"><code>n</code></dfn></dt>
<dd>
<p>Gives the structured name of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span title="concept-item">item</span> with zero or more of
each of the <code
title="md-vcard-n-family-name">family-name</code>, <code
title="md-vcard-n-given-name">given-name</code>, <code
title="md-vcard-n-additional-name">additional-name</code>, <code
title="md-vcard-n-honorific-prefix">honorific-prefix</code>, and
<code title="md-vcard-n-honorific-suffix">honorific-suffix</code>
properties.</p>
<p>Except when one of the conditions given below applies, exactly
one property with the name <code title="md-vcard-n">n</code> must
be present within each <span title="concept-item">item</span> with
the type <code title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
<p>If one of the following conditions does apply, then the <code
title="md-vcard-n">n</code> may be omitted:</p>
<dl>
<dt>The <span title="concept-item">item</span> with the type
<code title="">vcard</code> has both an <code
title="md-vcard-fn">fn</code> property and an <code
title="md-vcard-org">org</code> property, and they both have
<span title="concept-property-value">values</span> that are
strings and those strings are identical when compared in a
<span>case-sensitive</span> manner.</dt>
<dd>
<p>The contact information must be for an organization.</p>
</dd>
<dt>The <span title="concept-item">item</span> with the type
<code title="">vcard</code> has an <code
title="md-vcard-fn">fn</code> property whose <span
title="concept-property-value">value</span> consists of a string
with zero <span title="space character">space
characters</span>.</dt>
<dd>
<p>The <span title="concept-property-value">value</span> of the
<code title="md-vcard-fn">fn</code> property must be a
nickname.</p>
</dd>
<dt>The <span title="concept-item">item</span> with the type
<code title="">vcard</code> has an <code
title="md-vcard-fn">fn</code> property whose <span
title="concept-property-value">value</span> consists of a string
with exactly one sequence of <span title="space character">space
characters</span>, which occurs neither at the immediate start
nor the immediate end of the string.</dt>
<dd>
<p>The <span title="concept-property-value">value</span> of the
<code title="md-vcard-fn">fn</code> property must be a name in
one of the following forms:</p>
<ul class="brief">
<li>Last, First</li>
<li>Last F.</li>
<li>Last F</li>
<li>First Last</li>
</ul>
</dd>
</dl>
</dd>
<dt><dfn title="md-vcard-n-family-name"><code>family-name</code></dfn> (inside <code title="md-vcard-n">n</code>)</dt>
<dd>
<p>Gives the family name of the person, or the full name of the
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-n-family-name">family-name</code> may be present
within the <span title="concept-item">item</span> that forms the
<span title="concept-property-value">value</span> of the <code
title="md-vcard-n">n</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-n-given-name"><code>given-name</code></dfn> (inside <code title="md-vcard-n">n</code>)</dt>
<dd>
<p>Gives the given-name of the person.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-n-given-name">given-name</code> may be present
within the <span title="concept-item">item</span> that forms the
<span title="concept-property-value">value</span> of the <code
title="md-vcard-n">n</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-n-additional-name"><code>additional-name</code></dfn> (inside <code title="md-vcard-n">n</code>)</dt>
<dd>
<p>Gives the any additional names of the person.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-n-additional-name">additional-name</code> may be
present within the <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of the
<code title="md-vcard-n">n</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-n-honorific-prefix"><code>honorific-prefix</code></dfn> (inside <code title="md-vcard-n">n</code>)</dt>
<dd>
<p>Gives the honorific prefix of the person.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-n-honorific-prefix">honorific-prefix</code> may be
present within the <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of the
<code title="md-vcard-n">n</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-n-honorific-suffix"><code>honorific-suffix</code></dfn> (inside <code title="md-vcard-n">n</code>)</dt>
<dd>
<p>Gives the honorific suffix of the person.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-n-honorific-suffix">honorific-suffix</code> may be
present within the <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of the
<code title="md-vcard-n">n</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-nickname"><code>nickname</code></dfn></dt>
<dd>
<p>Gives the nickname of the person or organization.</p>
<!-- copied from vCard -->
<p class="note">The nickname is the descriptive name given instead
of or in addition to the one belonging to a person, place, or
thing. It can also be used to specify a familiar form of a proper
name specified by the <code title="md-vcard-fn">fn</code> or <code
title="md-vcard-n">n</code> properties.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-nickname">nickname</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-photo"><code>photo</code></dfn></dt>
<dd>
<p>Gives a photograph of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>Any number of properties with the name <code
title="md-vcard-photo">photo</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-bday"><code>bday</code></dfn></dt>
<dd>
<p>Gives the birth date of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be a
<span>valid date string</span>.</p>
<p>A single property with the name <code
title="md-vcard-bday">bday</code> may be present within each <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-adr"><code>adr</code></dfn></dt>
<dd>
<p>Gives the delivery address of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span title="concept-item">item</span> with zero or more <code
title="md-vcard-adr-type">type</code>, <code
title="md-vcard-adr-post-office-box">post-office-box</code>, <code
title="md-vcard-adr-extended-address">extended-address</code>, and
<code title="md-vcard-adr-street-address">street-address</code>
properties, and optionally a <code
title="md-vcard-adr-locality">locality</code> property, optionally
a <code title="md-vcard-adr-region">region</code> property,
optionally a <code
title="md-vcard-adr-postal-code">postal-code</code> property, and
optionally a <code
title="md-vcard-adr-country-name">country-name</code>
property.</p>
<p>If no <code title="md-vcard-adr-type">type</code> properties
are present within an <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of an
<code title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, then the <span>address type
strings</span> <code title="mv-vcard-type-adr-intl">intl</code>,
<code title="mv-vcard-type-adr-postal">postal</code>, <code
title="mv-vcard-type-adr-parcel">parcel</code>, and <code
title="mv-vcard-type-adr-work">work</code> are implied.</p>
<p>Any number of properties with the name <code
title="md-vcard-adr">adr</code> may be present within each <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-adr-type"><code>type</code></dfn> (inside <code title="md-vcard-adr">adr</code>)</dt>
<dd>
<p>Gives the type of delivery address.</p>
<p>The <span title="concept-property-value">value</span> must be
text that, when compared in a <span>case-sensitive</span> manner,
is equal to one of the <span>address type strings</span>.</p>
<p>Within each <span title="concept-item">item</span> with the
type <code title="md-vcard">http://microformats.org/profile/hcard</code>, there must be no more
than one <code title="md-vcard-adr">adr</code> property <span
title="concept-item">item</span> with a <code
title="md-vcard-adr-type">type</code> property whose value is
<code title="md-vcard-type-adr-pref">pref</code>.</p>
<p>Any number of properties with the name <code
title="md-vcard-adr-type">type</code> may be present within the
<span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of an <code
title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, but within each such <code
title="md-vcard-adr">adr</code> property <span
title="concept-item">item</span> there must only be one <code
title="md-vcard-adr-type">type</code> property per distinct
value.</p>
</dd>
<dt><dfn title="md-vcard-adr-post-office-box"><code>post-office-box</code></dfn> (inside <code title="md-vcard-adr">adr</code>)</dt>
<dd>
<p>Gives the post office box component of the delivery address of
the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-adr-post-office-box">post-office-box</code> may be
present within the <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of an
<code title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-adr-extended-address"><code>extended-address</code></dfn> (inside <code title="md-vcard-adr">adr</code>)</dt>
<dd>
<p>Gives an additional component of the delivery address of the
person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-adr-extended-address">extended-address</code> may
be present within the <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of an
<code title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-adr-street-address"><code>street-address</code></dfn> (inside <code title="md-vcard-adr">adr</code>)</dt>
<dd>
<p>Gives the street address component of the delivery address of
the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-adr-street-address">street-address</code> may be
present within the <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of an
<code title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-adr-locality"><code>locality</code></dfn> (inside <code title="md-vcard-adr">adr</code>)</dt>
<dd>
<p>Gives the locality component (e.g. city) of the delivery
address of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>A single property with the name <code
title="md-vcard-adr-locality">locality</code> may be present
within the <span title="concept-item">item</span> that forms the
<span title="concept-property-value">value</span> of an <code
title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-adr-region"><code>region</code></dfn> (inside <code title="md-vcard-adr">adr</code>)</dt>
<dd>
<p>Gives the region component (e.g. state or province) of the
delivery address of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>A single property with the name <code
title="md-vcard-adr-region">region</code> may be present within
the <span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of an <code
title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-adr-postal-code"><code>postal-code</code></dfn> (inside <code title="md-vcard-adr">adr</code>)</dt>
<dd>
<p>Gives the postal code component of the delivery address of the
person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>A single property with the name <code
title="md-vcard-adr-postal-code">postal-code</code> may be present
within the <span title="concept-item">item</span> that forms the
<span title="concept-property-value">value</span> of an <code
title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-adr-country-name"><code>country-name</code></dfn> (inside <code title="md-vcard-adr">adr</code>)</dt>
<dd>
<p>Gives the country name component of the delivery address of the
person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>A single property with the name <code
title="md-vcard-adr-country-name">country-name</code> may be
present within the <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of an
<code title="md-vcard-adr">adr</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-label"><code>label</code></dfn></dt>
<dd>
<p>Gives the formatted text corresponding to the delivery address
of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
either text or an <span title="concept-item">item</span> with zero
or more <code title="md-vcard-label-type">type</code> properties
and exactly one <code title="md-vcard-label-value">value</code>
property.</p>
<p>If no <code title="md-vcard-label-type">type</code> properties
are present within an <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of a
<code title="md-vcard-label">label</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, or if the <span
title="concept-property-value">value</span> of such a <code
title="md-vcard-label">label</code> property is text, then the
<span>address type strings</span> <code
title="mv-vcard-type-adr-intl">intl</code>, <code
title="mv-vcard-type-adr-postal">postal</code>, <code
title="mv-vcard-type-adr-parcel">parcel</code>, and <code
title="mv-vcard-type-adr-work">work</code> are implied.</p>
<p>Any number of properties with the name <code
title="md-vcard-label">label</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-label-type"><code>type</code></dfn> (inside <code title="md-vcard-label">label</code>)</dt>
<dd>
<p>Gives the type of delivery address.</p>
<p>The <span title="concept-property-value">value</span> must be
text that, when compared in a <span>case-sensitive</span> manner,
is equal to one of the <span>address type strings</span>.</p>
<p>Within each <span title="concept-item">item</span> with the
type <code title="md-vcard">http://microformats.org/profile/hcard</code>, there must be no more
than one <code title="md-vcard-label">label</code> property <span
title="concept-item">item</span> with a <code
title="md-vcard-label-type">type</code> property whose value is
<code title="md-vcard-type-adr-pref">pref</code>.</p>
<p>Any number of properties with the name <code
title="md-vcard-label-type">type</code> may be present within the
<span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of a <code
title="md-vcard-label">label</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, but within each such <code
title="md-vcard-label">label</code> property <span
title="concept-item">item</span> there must only be one <code
title="md-vcard-label-type">type</code> property per distinct
value.</p>
</dd>
<dt><dfn title="md-vcard-label-value"><code>value</code></dfn> (inside <code title="md-vcard-label">label</code>)</dt>
<dd>
<p>Gives the actual formatted text corresponding to the delivery
address of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Exactly one property with the name <code
title="md-vcard-label-value">value</code> must be present within
the <span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of a <code
title="md-vcard-label">label</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-tel"><code>tel</code></dfn></dt>
<dd>
<p>Gives the telephone number of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
either text that can be interpreted as a telephone number as
defined in the CCITT specifications E.163 and X.121, or an <span
title="concept-item">item</span> with zero or more <code
title="md-vcard-tel-type">type</code> properties and exactly one
<code title="md-vcard-tel-value">value</code> property. <a
href="#refsE163">[E163]</a> <a href="#refsX121">[X121]</a></p>
<p>If no <code title="md-vcard-tel-type">type</code> properties
are present within an <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of a
<code title="md-vcard-tel">tel</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, or if the <span
title="concept-property-value">value</span> of such a <code
title="md-vcard-tel">tel</code> property is text, then the <span
title="telephone type strings">telephone type string</span> <code
title="mv-vcard-type-tel-voice">voice</code> is implied.</p>
<p>Any number of properties with the name <code
title="md-vcard-tel">tel</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-tel-type"><code>type</code></dfn> (inside <code title="md-vcard-tel">tel</code>)</dt>
<dd>
<p>Gives the type of telephone number.</p>
<p>The <span title="concept-property-value">value</span> must be
text that, when compared in a <span>case-sensitive</span> manner,
is equal to one of the <span>telephone type strings</span>.</p>
<p>Within each <span title="concept-item">item</span> with the
type <code title="md-vcard">http://microformats.org/profile/hcard</code>, there must be no more
than one <code title="md-vcard-tel">tel</code> property <span
title="concept-item">item</span> with a <code
title="md-vcard-tel-type">type</code> property whose value is
<code title="md-vcard-type-tel-pref">pref</code>.</p>
<p>Any number of properties with the name <code
title="md-vcard-tel-type">type</code> may be present within the
<span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of a <code
title="md-vcard-tel">tel</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, but within each such <code
title="md-vcard-tel">tel</code> property <span
title="concept-item">item</span> there must only be one <code
title="md-vcard-tel-type">type</code> property per distinct
value.</p>
</dd>
<dt><dfn title="md-vcard-tel-value"><code>value</code></dfn> (inside <code title="md-vcard-tel">tel</code>)</dt>
<dd>
<p>Gives the actual telephone number of the person or
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text that can be interpreted as a telephone number as defined in
the CCITT specifications E.163 and X.121. <a
href="#refsE163">[E163]</a> <a href="#refsX121">[X121]</a></p>
<p>Exactly one property with the name <code
title="md-vcard-tel-value">value</code> must be present within the
<span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of a <code
title="md-vcard-tel">tel</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-email"><code>email</code></dfn></dt>
<dd>
<p>Gives the e-mail address of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
either text or an <span title="concept-item">item</span> with zero
or more <code title="md-vcard-email-type">type</code> properties
and exactly one <code title="md-vcard-email-value">value</code>
property.</p>
<p>If no <code title="md-vcard-email-type">type</code> properties
are present within an <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of an
<code title="md-vcard-email">email</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, or if the <span
title="concept-property-value">value</span> of such an <code
title="md-vcard-email">email</code> property is text, then the
<span title="e-mail type strings">e-mail type string</span> <code
title="mv-vcard-type-email-internet">internet</code> is
implied.</p>
<p>Any number of properties with the name <code
title="md-vcard-email">email</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-email-type"><code>type</code></dfn> (inside <code title="md-vcard-email">email</code>)</dt>
<dd>
<p>Gives the type of e-mail address.</p>
<p>The <span title="concept-property-value">value</span> must be
text that, when compared in a <span>case-sensitive</span> manner,
is equal to one of the <span>e-mail type strings</span>.</p>
<p>Within each <span title="concept-item">item</span> with the
type <code title="md-vcard">http://microformats.org/profile/hcard</code>, there must be no more
than one <code title="md-vcard-email">email</code> property <span
title="concept-item">item</span> with a <code
title="md-vcard-email-type">type</code> property whose value is
<code title="md-vcard-type-email-pref">pref</code>.</p>
<p>Any number of properties with the name <code
title="md-vcard-email-type">type</code> may be present within the
<span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of an <code
title="md-vcard-email">email</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, but within each such <code
title="md-vcard-email">email</code> property <span
title="concept-item">item</span> there must only be one <code
title="md-vcard-email-type">type</code> property per distinct
value.</p>
</dd>
<dt><dfn title="md-vcard-email-value"><code>value</code></dfn> (inside <code title="md-vcard-email">email</code>)</dt>
<dd>
<p>Gives the actual e-mail address of the person or
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Exactly one property with the name <code
title="md-vcard-email-value">value</code> must be present within
the <span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of an <code
title="md-vcard-email">email</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-mailer"><code>mailer</code></dfn></dt>
<dd>
<p>Gives the name of the e-mail software used by the person or
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-mailer">mailer</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-tz"><code>tz</code></dfn></dt>
<dd>
<p>Gives the time zone of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text and must match the following syntax:</p>
<ol>
<li>Either a U+002B PLUS SIGN character (+) or a U+002D
HYPHEN-MINUS character (-).</li>
<li>A <span>valid non-negative integer</span> that is exactly two
digits long and that represents a number in the range
00..23.</li>
<li>A U+003A COLON character (:).</li>
<li>A <span>valid non-negative integer</span> that is exactly two
digits long and that represents a number in the range
00..59.</li>
</ol>
<p>Any number of properties with the name <code
title="md-vcard-tz">tz</code> may be present within each <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-geo"><code>geo</code></dfn></dt>
<dd>
<p>Gives the geographical position of the person or
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text and must match the following syntax:</p>
<ol>
<li>Optionally, either a U+002B PLUS SIGN character (+) or a
U+002D HYPHEN-MINUS character (-).</li>
<li>One or more digits in the range U+0030 DIGIT ZERO (0) to
U+0039 DIGIT NINE (9).</li>
<li>Optionally*, a U+002E FULL STOP character (.) followed by one
or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
NINE (9).</li>
<li>A U+003B SEMICOLON character (;).</li>
<li>Optionally, either a U+002B PLUS SIGN character (+) or a
U+002D HYPHEN-MINUS character (-).</li>
<li>One or more digits in the range U+0030 DIGIT ZERO (0) to U+0039
DIGIT NINE (9).</li>
<li>Optionally*, a U+002E FULL STOP character (.) followed by one
or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
NINE (9).</li>
</ol>
<p>The optional components marked with an asterisk (*) should be
included, and should have six digits each.</p>
<!-- copied from vCard -->
<p class="note">The value specifies latitude and longitude, in
that order (i.e., "LAT LON" ordering), in decimal degrees. The
longitude represents the location east and west of the prime
meridian as a positive or negative real number, respectively. The
latitude represents the location north and south of the equator as
a positive or negative real number, respectively.</p>
<p>Any number of properties with the name <code
title="md-vcard-geo">geo</code> may be present within each <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-title"><code>title</code></dfn></dt>
<dd>
<p>Gives the job title, functional position or function of the
person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-title">title</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-role"><code>role</code></dfn></dt>
<dd>
<p>Gives the role, occupation, or business category of the person
or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-role">role</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-logo"><code>logo</code></dfn></dt>
<dd>
<p>Gives the logo of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>Any number of properties with the name <code
title="md-vcard-logo">logo</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-agent"><code>agent</code></dfn></dt>
<dd>
<p>Gives the contact information of another person who will act on
behalf of the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
either an <span title="concept-item">item</span> with the type
<code title="md-vcard">http://microformats.org/profile/hcard</code>, or an <span>absolute
URL</span>, or text.</p>
<p>Any number of properties with the name <code
title="md-vcard-logo">logo</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-org"><code>org</code></dfn></dt>
<dd>
<p>Gives the name and units of the organization.</p>
<p>The <span title="concept-property-value">value</span> must be
either text or an <span title="concept-item">item</span> with one
<code
title="md-vcard-org-organization-name">organization-name</code>
property and zero or more <code
title="md-vcard-n-organization-unit">organization-unit</code>
properties.</p>
<p>Any number of properties with the name <code
title="md-vcard-org">org</code> may be present within each <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-org-organization-name"><code>organization-name</code></dfn> (inside <code title="md-vcard-org">org</code>)</dt>
<dd>
<p>Gives the name of the organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Exactly one property with the name <code
title="md-vcard-org-organization-name">organization-name</code>
must be present within the <span title="concept-item">item</span>
that forms the <span title="concept-property-value">value</span>
of an <code title="md-vcard-org">org</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-org-organization-unit"><code>organization-unit</code></dfn> (inside <code title="md-vcard-org">org</code>)</dt>
<dd>
<p>Gives the name of the organization unit.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-org-organization-unit">organization-unit</code>
may be present within the <span title="concept-item">item</span>
that forms the <span title="concept-property-value">value</span>
of the <code title="md-vcard-org">org</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-categories"><code>categories</code></dfn></dt>
<dd>
<p>Gives the name of a category or tag that the person or
organization could be classified as.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-categories">categories</code> may be present
within each <span title="concept-item">item</span> with the type
<code title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-note"><code>note</code></dfn></dt>
<dd>
<p>Gives supplemental information or a comment about the person or
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-note">note</code> may be present
within each <span title="concept-item">item</span> with the type
<code title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<!-- PRODID not included -->
<dt><dfn title="md-vcard-rev"><code>rev</code></dfn></dt>
<dd>
<p>Gives the revision date and time of the contact
information.</p>
<p>The <span title="concept-property-value">value</span> must be
text that is a <span>valid global date and time string</span>.</p>
<!-- copied from vCard -->
<p class="note">The value distinguishes the current revision of
the information for other renditions of the information.</p>
<p>Any number of properties with the name <code
title="md-vcard-rev">rev</code> may be present within each <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-sort-string"><code>sort-string</code></dfn></dt>
<dd>
<p>Gives the string to be used for sorting the person or
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vcard-sort-string">sort-string</code> may be present
within each <span title="concept-item">item</span> with the type
<code title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-sound"><code>sound</code></dfn></dt>
<dd>
<p>Gives a sound file relating to the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>Any number of properties with the name <code
title="md-vcard-sound">sound</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<!-- UID not included - use "itemid" -->
<dt><dfn title="md-vcard-url"><code>url</code></dfn></dt>
<dd>
<p>Gives a <span>URL</span> relating to the person or
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>Any number of properties with the name <code
title="md-vcard-url">url</code> may be present within each <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<!-- VERSION not included - always 3.0 -->
<dt><dfn title="md-vcard-class"><code>class</code></dfn></dt>
<dd>
<p>Gives the access classification of the information regarding
the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
text with one of the following values:</p>
<ul class="brief">
<li><code title="">public</code></li>
<li><code title="">private</code></li>
<li><code title="">confidential</code></li>
</ul>
<p class="warning">This is merely advisory and cannot be
considered a confidentiality measure.</p>
<p>Any number of properties with the name <code
title="md-vcard-class">class</code> may be present
within each <span title="concept-item">item</span> with the type
<code title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<!-- KEY not included - no way to include binary data at this time -->
<!-- IMPP is from RFC4770 -->
<dt><dfn title="md-vcard-impp"><code>impp</code></dfn></dt>
<dd>
<p>Gives a <span>URL</span> for instant messaging and presence
protocol communications with the person or organization.</p>
<p>The <span title="concept-property-value">value</span> must be
either an <span>absolute URL</span> or an <span
title="concept-item">item</span> with zero or more <code
title="md-vcard-impp-type">type</code> properties and exactly one
<code title="md-vcard-impp-value">value</code> property.</p>
<p>If no <code title="md-vcard-impp-type">type</code> properties
are present within an <span title="concept-item">item</span> that
forms the <span title="concept-property-value">value</span> of an
<code title="md-vcard-impp">impp</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, or if the <span
title="concept-property-value">value</span> of such an <code
title="md-vcard-impp">impp</code> property is an <span>absolute
URL</span>, then no <span>IMPP type strings</span> are
implied.</p>
<p>Any number of properties with the name <code
title="md-vcard-impp">impp</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
<dt><dfn title="md-vcard-impp-type"><code>type</code></dfn> (inside <code title="md-vcard-impp">impp</code>)</dt>
<dd>
<p>Gives the intended use of the IMPP <span>URL</span>.</p>
<p>The <span title="concept-property-value">value</span> must be
text that, when compared in a <span>case-sensitive</span> manner,
is equal to one of the <span>IMPP type strings</span>.</p>
<p>Within each <span title="concept-item">item</span> with the
type <code title="md-vcard">http://microformats.org/profile/hcard</code>, there must be no more
than one <code title="md-vcard-impp">impp</code> property <span
title="concept-item">item</span> with a <code
title="md-vcard-impp-type">type</code> property whose value is
<code title="md-vcard-type-impp-pref">pref</code>.</p>
<p>Any number of properties with the name <code
title="md-vcard-impp-type">type</code> may be present within the
<span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of an <code
title="md-vcard-impp">impp</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>, but within each such <code
title="md-vcard-impp">impp</code> property <span
title="concept-item">item</span> there must only be one <code
title="md-vcard-impp-type">type</code> property per distinct
value.</p>
</dd>
<dt><dfn title="md-vcard-impp-value"><code>value</code></dfn> (inside <code title="md-vcard-impp">impp</code>)</dt>
<dd>
<p>Gives the actual <span>URL</span> for instant messaging and
presence protocol communications with the person or
organization.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>Exactly one property with the name <code
title="md-vcard-impp-value">value</code> must be present within
the <span title="concept-item">item</span> that forms the <span
title="concept-property-value">value</span> of an <code
title="md-vcard-impp">impp</code> property of an <span
title="concept-item">item</span> with the type <code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p>
</dd>
</dl>
<p>The <dfn>address type strings</dfn> are:</p>
<dl>
<dt><dfn title="md-vcard-type-adr-dom"><code>dom</code></dfn></dt>
<dd>
<p>Indicates a domestic delivery address.</p>
<dd>
<dt><dfn title="md-vcard-type-adr-intl"><code>intl</code></dfn></dt>
<dd>
<p>Indicates an international delivery address.</p>
<dd>
<dt><dfn title="md-vcard-type-adr-postal"><code>postal</code></dfn></dt>
<dd>
<p>Indicates a postal delivery address.</p>
<dd>
<dt><dfn title="md-vcard-type-adr-parcel"><code>parcel</code></dfn></dt>
<dd>
<p>Indicates a parcel delivery address.</p>
<dd>
<dt><dfn title="md-vcard-type-adr-home"><code>home</code></dfn></dt>
<dd>
<p>Indicates a residential delivery address.</p>
<dd>
<dt><dfn title="md-vcard-type-adr-work"><code>work</code></dfn></dt>
<dd>
<p>Indicates a delivery address for a place of work.</p>
<dd>
<dt><dfn title="md-vcard-type-adr-pref"><code>pref</code></dfn></dt>
<dd>
<p>Indicates the preferred delivery address when multiple
addresses are specified.</p>
<dd>
</dl>
<p>The <dfn>telephone type strings</dfn> are:</p>
<dl>
<dt><dfn title="md-vcard-type-tel-home"><code>home</code></dfn></dt>
<dd>
<p>Indicates a residential number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-msg"><code>msg</code></dfn></dt>
<dd>
<p>Indicates a telephone number with voice messaging support.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-work"><code>work</code></dfn></dt>
<dd>
<p>Indicates a telephone number for a place of work.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-voice"><code>voice</code></dfn></dt>
<dd>
<p>Indicates a voice telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-fax"><code>fax</code></dfn></dt>
<dd>
<p>Indicates a facsimile telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-cell"><code>cell</code></dfn></dt>
<dd>
<p>Indicates a cellular telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-video"><code>video</code></dfn></dt>
<dd>
<p>Indicates a video conferencing telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-pager"><code>pager</code></dfn></dt>
<dd>
<p>Indicates a paging device telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-bbs"><code>bbs</code></dfn></dt>
<dd>
<p>Indicates a bulletin board system telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-modem"><code>modem</code></dfn></dt>
<dd>
<p>Indicates a MODEM-connected telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-car"><code>car</code></dfn></dt>
<dd>
<p>Indicates a car-phone telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-isdn"><code>isdn</code></dfn></dt>
<dd>
<p>Indicates an ISDN service telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-pcs"><code>pcs</code></dfn></dt>
<dd>
<p>Indicates a personal communication services telephone number.</p>
<dd>
<dt><dfn title="md-vcard-type-tel-pref"><code>pref</code></dfn></dt>
<dd>
<p>Indicates the preferred telephone number when multiple
telephone numbers are specified.</p>
<dd>
</dl>
<p>The <dfn>e-mail type strings</dfn> are:</p>
<dl>
<dt><dfn title="md-vcard-type-email-internet"><code>internet</code></dfn></dt>
<dd>
<p>Indicates an Internet e-mail address.</p>
<dd>
<dt><dfn title="md-vcard-type-email-x400"><code>x400</code></dfn></dt>
<dd>
<p>Indicates a X.400 addressing type.</p>
<dd>
<dt><dfn title="md-vcard-type-email-pref"><code>pref</code></dfn></dt>
<dd>
<p>Indicates the preferred e-mail address when multiple e-mail
addresses are specified.</p>
<dd>
</dl>
<p>The <dfn>IMPP type strings</dfn> are:</p>
<dl>
<dt><dfn title="md-vcard-type-impp-personal"><code>personal</code></dfn></dt>
<dt><dfn title="md-vcard-type-impp-business"><code>business</code></dfn></dt>
<dd>
<p>Indicates the type of communication for which this IMPP
<span>URL</span> is appropriate.</p>
<dd>
<dt><dfn title="md-vcard-type-impp-home"><code>home</code></dfn></dt>
<dt><dfn title="md-vcard-type-impp-work"><code>work</code></dfn></dt>
<dt><dfn title="md-vcard-type-impp-mobile"><code>mobile</code></dfn></dt>
<dd>
<p>Indicates the location of a device associated with this IMPP
<span>URL</span>.</p>
<dd>
<dt><dfn title="md-vcard-type-impp-pref"><code>pref</code></dfn></dt>
<dd>
<p>Indicates the preferred address when multiple IMPP
<span>URL</span>s are specified.</p>
<dd>
</dl>
<h5>Conversion to vCard</h5>
<p>Given a list of nodes <var title="">nodes</var> in a
<code>Document</code>, a user agent must run the following algorithm
to <dfn title="extracting a vCard">extract any vCard data
represented by those nodes</dfn> (only the first vCard is
returned):</p>
<ol>
<li><p>If none of the nodes in <var title="">nodes</var> are <span
title="concept-item">items</span> with the <span>item type</span>
<code
title="md-vcard">http://microformats.org/profile/hcard</code>, then
there is no vCard. Abort the algorithm, returning nothing.</p></li>
<li><p>Let <var title="">node</var> be the first node in <var
title="">nodes</var> that is an <span
title="concept-item">item</span> with the <span>item type</span>
<code
title="md-vcard">http://microformats.org/profile/hcard</code>.</p></li>
<li><p>Let <var title="">output</var> be an empty string.</p></li>
<li><p><span>Add a vCard line</span> with the type "<code
title="">BEGIN</code>" and the value "<code title="">VCARD</code>"
to <var title="">output</var>.</p></li>
<li><p><span>Add a vCard line</span> with the type "<code
title="">PROFILE</code>" and the value "<code
title="">VCARD</code>" to <var title="">output</var>.</p></li>
<li><p><span>Add a vCard line</span> with the type "<code
title="">VERSION</code>" and the value "<code title="">3.0</code>"
to <var title="">output</var>.</p></li>
<li><p><span>Add a vCard line</span> with the type "<code
title="">SOURCE</code>" and the result of <span>escaping the vCard
text string</span> that is <span>the document's current
address</span> as the value to <var title="">output</var>.</p></li>
<li><p>If <span>the <code>title</code> element</span> is not null,
<span>add a vCard line</span> with the type "<code
title="">NAME</code>" and with the result of <span>escaping the
vCard text string</span> obtained from the <code>textContent</code>
of <span>the <code>title</code> element</span> as the value to <var
title="">output</var>.</p></li>
<li><p>If <var title="">node</var> has a <span>global
identifier</span>, <span>add a vCard line</span> with the type
"<code title="">UID</code>" and with the result of <span>escaping
the vCard text string</span> of that <span>global identifier</span>
as the value to <var title="">output</var>.</p></li>
<li><p>Let <var title="">first-n</var>, <var
title="">first-org</var>, and <var title="">first-fn</var> be
null.</p></li>
<li>
<p>For each element <var title="">element</var> that is <span
title="the properties of an item">a property of the item</span>
<var title="">node</var>: for each name <var title="">name</var>
in <var title="">element</var>'s <span>property names</span>, run
the following substeps:</p>
<ol>
<li><p>Let <var title="">parameters</var> be an empty set of
name-value pairs.</p></li>
<li>
<p>Run the appropriate set of substeps from the following
list. The steps will set a variable <var title="">value</var>,
which is used in the next step.</p>
<dl>
<dt>If the property's <span
title="concept-property-value">value</span> is an <span
title="concept-item">item</span> <var title="">subitem</var>
and <var title="">name</var> is <code
title="md-vcard-n">n</code></dt>
<dd>
<ol>
<li><p>If <var title="">first-n</var> is null, let <var
title="">first-n</var> be <var title="">element</var>.</p></li>
<li><p>Let <var title="">n1</var> be the <span
title="concept-property-value">value</span> of the first
property named <code
title="md-vcard-n-family-name">family-name</code> in <var
title="">subitem</var>, or the empty string if there is no
such property or the property's value is itself an <span
title="concept-item">item</span>.</p></li>
<li><p>Let <var title="">n2</var> be the <span
title="concept-property-value">value</span> of the first
property named <code
title="md-vcard-n-given-name">given-name</code> in <var
title="">subitem</var>, or the empty string if there is no
such property or the property's value is itself an <span
title="concept-item">item</span>.</p></li>
<li><p>Let <var title="">n3</var> be the <span
title="concept-property-value">value</span> of the first
property named <code
title="md-vcard-n-additional-name">additional-name</code> in
<var title="">subitem</var>, or the empty string if there is
no such property or the property's value is itself an <span
title="concept-item">item</span>.</p></li>
<li><p>Let <var title="">n4</var> be the <span
title="concept-property-value">value</span> of the first
property named <code
title="md-vcard-n-honorific-prefix">honorific-prefix</code>
in <var title="">subitem</var>, or the empty string if there
is no such property or the property's value is itself an
<span title="concept-item">item</span>.</p></li>
<li><p>Let <var title="">n5</var> be the <span
title="concept-property-value">value</span> of the first
property named <code
title="md-vcard-n-honorific-suffix">honorific-suffix</code>
in <var title="">subitem</var>, or the empty string if there
is no such property or the property's value is itself an
<span title="concept-item">item</span>.</p></li>
<li>
<p>Let <var title="">value</var> be the concatenation of the
following, in this order:</p>
<ol class="brief">
<li>The result of <span>escaping the vCard text string</span> <var title="">n1</var></li>
<li>A U+003B SEMICOLON character (;)</li>
<li>The result of <span>escaping the vCard text string</span> <var title="">n2</var></li>
<li>A U+003B SEMICOLON character (;)</li>
<li>The result of <span>escaping the vCard text string</span> <var title="">n3</var></li>
<li>A U+003B SEMICOLON character (;)</li>
<li>The result of <span>escaping the vCard text string</span> <var title="">n4</var></li>
<li>A U+003B SEMICOLON character (;)</li>
<li>The result of <span>escaping the vCard text string</span> <var title="">n5</var></li>
</ol>
</li>
</ol>
</dd>
<dt>If the property's <span
title="concept-property-value">value</span> is an <span
title="concept-item">item</span> <var title="">subitem</var>
and <var title="">name</var> is <code
title="md-vcard-adr">adr</code></dt>
<dd>
<ol>
<li><p>Let <var title="">value</var> be the empty
string.</p></li>
<li><p>Append to <var title="">value</var> the result of
<span>collecting vCard subproperties</span> named <code
title="md-vcard-adr-post-office-box">post-office-box</code>
in <var title="">subitem</var>.</p>
<li>Append a U+003B SEMICOLON character (;) to <var
title="">value</var>.</li>
<li><p>Append to <var title="">value</var> the result of
<span>collecting vCard subproperties</span> named <code
title="md-vcard-adr-extended-address">extended-address</code>
in <var title="">subitem</var>.</p>
<li>Append a U+003B SEMICOLON character (;) to <var
title="">value</var>.</li>
<li><p>Append to <var title="">value</var> the result of
<span>collecting vCard subproperties</span> named <code
title="md-vcard-adr-street-address">street-address</code> in
<var title="">subitem</var>.</p>
<li>Append a U+003B SEMICOLON character (;) to <var
title="">value</var>.</li>
<li><p>Append to <var title="">value</var> the result of
<span>collecting the first vCard subproperty</span> named
<code title="md-vcard-adr-locality">locality</code> in <var
title="">subitem</var>.</p>
<li>Append a U+003B SEMICOLON character (;) to <var
title="">value</var>.</li>
<li><p>Append to <var title="">value</var> the result of
<span>collecting the first vCard subproperty</span> named
<code title="md-vcard-adr-region">region</code> in <var
title="">subitem</var>.</p>
<li>Append a U+003B SEMICOLON character (;) to <var
title="">value</var>.</li>
<li><p>Append to <var title="">value</var> the result of
<span>collecting the first vCard subproperty</span> named
<code title="md-vcard-adr-postal-code">postal-code</code> in
<var title="">subitem</var>.</p>
<li>Append a U+003B SEMICOLON character (;) to <var
title="">value</var>.</li>
<li><p>Append to <var title="">value</var> the result of
<span>collecting the first vCard subproperty</span> named
<code title="md-vcard-adr-country-name">country-name</code>
in <var title="">subitem</var>.</p>
<li><p>If there is a property named <code
title="md-vcard-adr-type">type</code> in <var
title="">subitem</var>, and the first such property has a
<span title="concept-property-value">value</span> that is not
an <span title="concept-item">item</span> and whose value
consists only of <span>alphanumeric ASCII characters</span>,
then add a parameter named "<code title="">TYPE</code>" whose
value is the <span
title="concept-property-value">value</span> of that property
to <var title="">parameters</var>.</p></li>
</ol>
</dd>
<dt>If the property's <span
title="concept-property-value">value</span> is an <span
title="concept-item">item</span> <var title="">subitem</var>
and <var title="">name</var> is <code
title="md-vcard-org">org</code></dt>
<dd>
<ol>
<li><p>If <var title="">first-org</var> is null, let <var
title="">first-org</var> be <var
title="">element</var>.</p></li>
<li><p>Let <var title="">value</var> be the empty
string.</p></li>
<li><p>Append to <var title="">value</var> the result of
<span>collecting the first vCard subproperty</span> named
<code
title="md-vcard-org-organization-name">organization-name</code>
in <var title="">subitem</var>.</p>
<li>
<p>For each property named <code
title="md-vcard-org-organization-unit">organization-unit</code>
in <var title="">subitem</var>, run the following steps:</p>
<ol>
<li><p>If the <span
title="concept-property-value">value</span> of the property
is an <span title="concept-item">item</span>, then skip
this property.</p></li>
<li><p>Append a U+003B SEMICOLON character (;) to <var
title="">value</var>.</p></li>
<li><p>Append the result of <span>escaping the vCard text
string</span> given by the <span
title="concept-property-value">value</span> of the property
to <var title="">value</var>.</p></li>
</ol>
</li>
</ol>
</dd>
<dt>If the property's <span
title="concept-property-value">value</span> is an <span
title="concept-item">item</span> <var title="">subitem</var>
with the <span>item type</span> <code
title="md-vcard">http://microformats.org/profile/hcard</code>
and <var title="">name</var> is <code
title="md-vcard-agent">agent</code></dt>
<dd>
<ol>
<li><p>Let <var title="">value</var> be the result of
<span>escaping the vCard text string</span> obtained from
<span>extracting a vCard</span> from the element that
represents <var title="">subitem</var>.</p></li>
<li><p>Add a parameter named "<code title="">VALUE</code>"
whose value is "<code title="">VCARD</code>" to <var
title="">parameters</var>.</p></li>
</ol>
</dd>
<dt>If the property's <span
title="concept-property-value">value</span> is an <span
title="concept-item">item</span> and <var title="">name</var>
is none of the above</dt>
<dd>
<ol>
<li><p>Let <var title="">value</var> the result of
<span>collecting the first vCard subproperty</span> named
<code title="">value</code> in <var
title="">subitem</var>.</p>
<li><p>If there is a property named <code
title="">type</code> in <var title="">subitem</var>, and the
first such property has a <span
title="concept-property-value">value</span> that is not an
<span title="concept-item">item</span> and whose value
consists only of <span>alphanumeric ASCII characters</span>,
then add a parameter named "<code title="">TYPE</code>" whose
value is the <span
title="concept-property-value">value</span> of that property
to <var title="">parameters</var>.</p></li>
</ol>
</dd>
<dt>Otherwise (the property's <span
title="concept-property-value">value</span> is not an <span
title="concept-item">item</span>)</dt>
<dd>
<ol>
<li>
<p>If <var title="">name</var> is <code
title="md-vcard-fn">fn</code> and <var
title="">first-fn</var> is null, let <var
title="">first-fn</var> be <var
title="">element</var>.</p>
<p>Otherwise, if <var title="">name</var> is <code
title="md-vcard-org">org</code> and <var
title="">first-org</var> is null, let <var
title="">first-org</var> be <var
title="">element</var>.</p>
</li>
<li><p>Let <var title="">value</var> be the property's <span
title="concept-property-value">value</span>.</p></li>
<li><p>If <var title="">element</var> is one of the <span>URL
property elements</span>, add a parameter with the name "<code
title="">VALUE</code>" and the value "<code
title="">URI</code>" to <var
title="">parameters</var>.</p></li>
<li><p>Otherwise, if <var title="">element</var> is a
<code>time</code> element and the <var title="">value</var> is
a <span>valid date string</span>, add a parameter with the name
"<code title="">VALUE</code>" and the value "<code
title="">DATE</code>" to <var
title="">parameters</var>.</p></li>
<li><p>Otherwise, if <var title="">element</var> is a
<code>time</code> element and the <var title="">value</var> is
a <span>valid global date and time string</span>, add a
parameter with the name "<code title="">VALUE</code>" and the
value "<code title="">DATE-TIME</code>" to <var
title="">parameters</var>.</p></li>
<li><p>Prefix every U+005C REVERSE SOLIDUS character (\) in
<var title="">value</var> with another U+005C REVERSE SOLIDUS
character (\).</p></li>
<li><p>Prefix every U+002C COMMA character (,) in <var
title="">value</var> with a U+005C REVERSE SOLIDUS character
(\).</p></li>
<li><p>Unless <var title="">name</var> is <code
title="md-vcard-geo">geo</code>, prefix every U+003B SEMICOLON
character (;) in <var title="">value</var> with a U+005C
REVERSE SOLIDUS character (\).</p></li>
<li><p>Replace every U+000D CARRIAGE RETURN U+000A LINE FEED
character pair (CRLF) in <var title="">value</var> with a
U+005C REVERSE SOLIDUS character (\) followed by a U+006E
LATIN SMALL LETTER N character (n).</p></li>
<li><p>Replace every remaining U+000D CARRIAGE RETURN (CR) or
U+000A LINE FEED (LF) character in <var title="">value</var>
with a U+005C REVERSE SOLIDUS character (\) followed by a
U+006E LATIN SMALL LETTER N character (n).</p></li>
</ol>
</dd>
</dl>
</li>
<li>
<p><span>Add a vCard line</span> with the type <var
title="">name</var>, the parameters <var
title="">parameters</var>, and the value <var
title="">value</var> to <var title="">output</var>.</p>
</li>
</ol>
</li>
<li>
<p>If <var title="">first-n</var> is null, then run the following
substeps:</p>
<ol>
<li><p>If <var title="">first-fn</var> is also null, then skip
the remainder of these substeps.</p></li>
<li><p>If <var title="">first-fn</var> has a <span
title="concept-property-value">value</span> that is an <span
title="concept-item">item</span>, then skip the remainder of
these substeps.</p></li>
<li><p>If <var title="">first-org</var> is not null, and the
<span title="concept-property-value">value</span> of <var
title="">first-org</var> is not an <span
title="concept-item">item</span> and is equal to <var
title="">first-fn</var>, then <span>add a vCard line</span> with
the type "<code title="">N</code>" whose value is four U+003B
SEMICOLON characters ("<code title="">;;;;</code>") to <var
title="">output</var>. Then, skip the remainder of these
substeps.</p></li>
<li><p>If the <span title="space character">space
characters</span> in <var title="">first-fn</var>, if any, are
not all contiguous, then skip the remainder of these
substeps.</p></li>
<li><p><span title="split a string on spaces">Split <var
title="">first-fn</var> on spaces</span>, and let <var
title="">part one</var> be the first resulting token, and <var
title="">part two</var> be the second, if any, or the empty
string if there is no second token. (There cannot be three, given
the previous step.)</p></li>
<li>
<p>If the last character of <var title="">part one</var> is a
U+002C COMMA character (,), then remove that character from <var
title="">part one</var> and <span>add a vCard line</span> with
the type "<code title="">N</code>" whose value is the
concatenation of the following strings:</p>
<ol class="brief">
<li>The result of <span>escaping the vCard text string</span> <var title="">part one</var></li>
<li>A U+003B SEMICOLON character (;)</li>
<li>The result of <span>escaping the vCard text string</span> <var title="">part two</var></li>
<li>Three U+003B SEMICOLON characters (;)</li>
</ol>
<p>Then, skip the remainder of these substeps.</p>
</li>
<li>
<p>If <var title="">part two</var> is two Unicode code-points
long and its second character is a U+002E FULL STOP character
(.), then <span>add a vCard line</span> with the type "<code
title="">N</code>" whose value is the concatenation of the
following strings:</p>
<ol class="brief">
<li>The result of <span>escaping the vCard text string</span> <var title="">part one</var></li>
<li>A U+003B SEMICOLON character (;)</li>
<li>The result of <span>escaping the vCard text string</span> consisting of the first character of <var title="">part two</var></li>
<li>Three U+003B SEMICOLON characters (;)</li>
</ol>
<p>Then, skip the remainder of these substeps.</p>
</li>
<li>
<p>If <var title="">part two</var> is one Unicode code-point
long, then <span>add a vCard line</span> with the type "<code
title="">N</code>" whose value is the concatenation of the
following strings:</p>
<ol class="brief">
<li>The result of <span>escaping the vCard text string</span> <var title="">part one</var></li>
<li>A U+003B SEMICOLON character (;)</li>
<li>The result of <span>escaping the vCard text string</span> <var title="">part two</var></li>
<li>Three U+003B SEMICOLON characters (;)</li>
</ol>
<p>Then, skip the remainder of these substeps.</p>
</li>
<li>
<p><span>Add a vCard line</span> with the type "<code
title="">N</code>" whose value is the concatenation of the
following strings:</p>
<ol class="brief">
<li>The result of <span>escaping the vCard text string</span> <var title="">part two</var></li>
<li>A U+003B SEMICOLON character (;)</li>
<li>The result of <span>escaping the vCard text string</span> <var title="">part one</var></li>
<li>Three U+003B SEMICOLON characters (;)</li>
</ol>
</li>
</ol>
</li>
<li><p><span>Add a vCard line</span> with the type "<code
title="">END</code>" and the value "<code title="">VCARD</code>"
to <var title="">output</var>.</p></li>
</ol>
<p>When the above algorithm says that the user agent is to <dfn>add
a vCard line</dfn> consisting of a type <var title="">type</var>,
optionally some parameters, and a value <var title="">value</var> to
a string <var title="">output</var>, it must run the following
steps:</p>
<ol>
<li><p>Let <var title="">line</var> be an empty string.
<li><p>Append <var title="">type</var>, <span>converted to
ASCII uppercase</span>, to <var title="">line</var>.</p></li>
<li>
<p>If there are any parameters, then for each parameter, in the
order that they were added, run these substeps:</p>
<ol>
<li><p>Append a U+003B SEMICOLON character (;) to <var
title="">line</var>.</p></li>
<li><p>Append the parameter's name to <var
title="">line</var>.</p></li>
<li><p>Append a U+003D EQUALS SIGN character (=) to <var
title="">line</var>.</p></li>
<li><p>Append the parameter's value to <var
title="">line</var>.</p></li>
</ol>
</li>
<li><p>Append a U+003A COLON character (:) to <var
title="">line</var>.</p></li>
<li><p>Append <var title="">value</var> to <var
title="">line</var>.</p></li>
<li><p>Let <var title="">maximum length</var> be 75.</p></li>
<li>
<p>If and while <var title="">line</var> is longer than <var
title="">maximum length</var> Unicode code points long, run the
following substeps:</p>
<ol>
<li><p>Append the first <var title="">maximum length</var>
Unicode code points of <var title="">line</var> to <var
title="">output</var>.</p></li>
<li><p>Remove the first <var title="">maximum length</var>
Unicode code points from <var title="">line</var>.</p></li>
<li><p>Append a U+000D CARRIAGE RETURN character (CR) to <var
title="">output</var>.</p></li>
<li><p>Append a U+000A LINE FEED character (LF) to <var
title="">output</var>.</p></li>
<li><p>Append a U+0020 SPACE character to <var
title="">output</var>.</p></li>
<li><p>Let <var title="">maximum length</var> be 74.</p></li>
</ol>
</li>
<li><p>Append (what remains of) <var title="">line</var> to <var
title="">output</var>.</p></li>
<li><p>Append a U+000D CARRIAGE RETURN character (CR) to <var
title="">output</var>.</p></li>
<li><p>Append a U+000A LINE FEED character (LF) to <var
title="">output</var>.</p></li>
</ol>
<p>When the steps above require the user agent to obtain the result
of <dfn>collecting vCard subproperties</dfn> named <var
title="">subname</var> in <var title="">subitem</var>, the user
agent must run the following steps:</p>
<ol>
<li><p>Let <var title="">value</var> be the empty string.</p></li>
<li>
<p>For each property named <var title="">subname</var> in the item
<var title="">subitem</var>, run the following substeps:</p>
<ol>
<li><p>If the <span title="concept-property-value">value</span>
of the property is itself an <span
title="concept-item">item</span>, then skip this
property.</p></li>
<li><p>If this is not the first property named <var
title="">subname</var> in <var title="">subitem</var> (ignoring
any that were skipped by the previous step), then append a U+002C
COMMA character (,) to <var title="">value</var>.</p></li>
<li><p>Append the result of <span>escaping the vCard text
string</span> given by the <span
title="concept-property-value">value</span> of the property to
<var title="">value</var>.</p></li>
</ol>
</li>
<li><p>Return <var title="">value</var>.</p></li>
</ol>
<p>When the steps above require the user agent to obtain the result
of <dfn>collecting the first vCard subproperty</dfn> named <var
title="">subname</var> in <var title="">subitem</var>, the user
agent must run the following steps:</p>
<ol>
<li><p>If there are no properties named <var title="">subname</var>
in <var title="">subitem</var>, then abort these substeps,
returning the empty string.</p></li>
<li><p>If the <span title="concept-property-value">value</span> of
the first property named <var title="">subname</var> in <var
title="">subitem</var> is an <span
title="concept-item">item</span>, then abort these substeps,
returning the empty string.</p></li>
<li><p>Return the result of <span>escaping the vCard text
string</span> given by the <span
title="concept-property-value">value</span> of the first property
named <var title="">subname</var> in <var
title="">subitem</var>.</p></li>
</ol>
<p>When the above algorithms say the user agent is to <dfn
title="escaping the vCard text string">escape the vCard text
string</dfn> <var title="">value</var>, the user agent must use the
following steps:</p>
<ol>
<li><p>Prefix every U+005C REVERSE SOLIDUS character (\) in <var
title="">value</var> with another U+005C REVERSE SOLIDUS character
(\).</p></li>
<li><p>Prefix every U+002C COMMA character (,) in <var
title="">value</var> with a U+005C REVERSE SOLIDUS character
(\).</p></li>
<li><p>Prefix every U+003B SEMICOLON character (;) in <var
title="">value</var> with a U+005C REVERSE SOLIDUS character
(\).</p></li>
<li><p>Replace every U+000D CARRIAGE RETURN U+000A LINE FEED
character pair (CRLF) in <var title="">value</var> with a U+005C
REVERSE SOLIDUS character (\) followed by a U+006E LATIN SMALL
LETTER N character (n).</p></li>
<li><p>Replace every remaining U+000D CARRIAGE RETURN (CR) or
U+000A LINE FEED (LF) character in <var title="">value</var> with a
U+005C REVERSE SOLIDUS character (\) followed by a U+006E LATIN
SMALL LETTER N character (n).</p></li>
<li><p>Return the mutated <var title="">value</var>.</p></li>
</ol>
<p class="note">This algorithm can generate invalid vCard output, if
the input does not conform to the rules described for the <code
title="md-vcard">http://microformats.org/profile/hcard</code>
<span>item type</span> and <span title="defined property
name">defined property names</span>.</p> <!-- of course since vcard
doesn't define error handling, this is somewhat problematic. -->
<h5>Examples</h5>
<div class="example">
<p>Here is a long example vCard for a fictional character called
"Jack Bauer":</p>
<pre><section id="jack" itemscope itemtype="http://microformats.org/profile/hcard">
<h1 itemprop="fn">Jack Bauer</h1>
<img itemprop="photo" alt="" src="jack-bauer.jpg">
<p itemprop="org" itemscope>
<span itemprop="organization-name">Counter-Terrorist Unit</span>
(<span itemprop="organization-unit">Los Angeles Division</span>)
</p>
<p>
<span itemprop="adr" itemscope>
<span itemprop="street-address">10201 W. Pico Blvd.</span><br>
<span itemprop="locality">Los Angeles</span>,
<span itemprop="region">CA</span>
<span itemprop="postal-code">90064</span><br>
<span itemprop="country-name">United States</span><br>
</span>
<span itemprop="geo">34.052339;-118.410623</span>
</p>
<h2>Assorted Contact Methods</h2>
<ul>
<li itemprop="tel" itemscope><span itemprop="value">+1 (310)
597 3781</span> <span itemprop="type">work</span> <meta
itemprop="type" content="pref"></li>
<li><a itemprop="url"
href="http://en.wikipedia.org/wiki/Jack_Bauer">I'm on
Wikipedia</a> so you can leave a message on my user talk
page.</li>
<li><a itemprop="url"
href="http://www.jackbauerfacts.com/">Jack Bauer Facts</a></li>
<li itemprop="email"><a
href="mailto:j.bauer@la.ctu.gov.invalid">j.bauer@la.ctu.gov.invalid</a></li>
<li itemprop="tel" itemscope><span itemprop="value">+1 (310) 555
3781</span> <span><meta itemprop="type" content="cell">mobile
phone</span></li>
</ul>
<p itemprop="note">If I'm out in the field, you may be better off
contacting <span itemprop="agent" itemscope
itemtype="http://microformats.org/profile/hcard"><a
itemprop="email" href="mailto:c.obrian@la.ctu.gov.invalid"><span
itemprop="fn">Chloe O'Brian</span></a></span> if it's about
work, or ask <span itemprop="agent">Tony Almeida</span> if
you're interested in the CTU five-a-side football team we're trying
to get going.</p>
<ins datetime="2008-07-20T21:00:00+0100">
<span itemprop="rev" itemscope>
<meta itemprop="type" content="date-time">
<meta itemprop="value" content="2008-07-20T21:00:00+0100">
</span>
<p itemprop="tel" itemscope><strong>Update!</strong>
My new <span itemprop="type">home</span> phone number is
<span itemprop="value">01632 960 123</span>.
</ins>
</section></pre>
</div>
<div class="example">
<p>This example shows a site's contact details (using the
<code>address</code> element) containing an address with two street
components:</p>
<pre><address itemscope itemtype="http://microformats.org/profile/hcard">
<strong title="fn">Alfred Person</strong> <br>
<span itemprop="adr" itemscope>
<span itemprop="street-address">1600 Amphitheatre Parkway</span> <br>
<span itemprop="street-address">Building 43, Second Floor</span> <br>
<span itemprop="locality">Mountain View</span>,
<span itemprop="region">CA</span> <span itemprop="postal-code">94043</span>
</span>
</address></pre>
</div>
<div class="example">
<p>The vCard vocabulary can be used to just mark up people's
names:</p>
<pre><span itemscope itemtype="http://microformats.org/profile/hcard"
><span itemprop=fn>George Washington</span></span></pre>
<p>This creates a single item with a single name-value pair, with
the name "fn" and the value "George Washington". This is defined to
map to the following vCard:</p>
<pre>BEGIN:VCARD
PROFILE:VCARD
VERSION:3.0
SOURCE:<var title="">document's address</var>
FN:George Washington
N:Washington;George;;;
END:VCARD</pre>
</div>
<!--END vCard-->
<h4>vEvent</h4>
<!--END vocabs--><!--END complete-->
<!--START vEvent-->
<h4 class="no-num no-toc">Table of contents</h4>
<!--toc-->
<hr>
<h5>The vocabulary</h5>
<p>This section defines a microdata vocabulary. <a
href="#refsHTML5">[HTML5]</a></p>
<!--START vocabs--><!--START complete-->
<p>An item with the <span>item type</span> <dfn
title="md-vevent"><code>http://microformats.org/profile/hcalendar#vevent</code></dfn>
represents an event.</p>
<p>This vocabulary <span title="support global identifiers for
items">supports global identifiers for items</span>.</p>
<p>The following are the type's <span title="defined property
name">defined property names</span>. They are based on the
vocabulary defined in the iCalendar specification, where more
information on how to interpret the values can be found. <a
href="#refsRFC2445">[RFC2445]</a></p>
<p class="note">Only the parts of the iCalendar vocabulary relating
to events are used here; this vocabulary cannot express a complete
iCalendar instance.</p>
<dl>
<dt><dfn title="md-vevent-attach"><code>attach</code></dfn></dt>
<dd>
<p>Gives the address of an associated document for the event.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>Any number of properties with the name <code
title="md-vevent-attach">attach</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-categories"><code>categories</code></dfn></dt>
<dd>
<p>Gives the name of a category or tag that the event could be
classified as.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vevent-categories">categories</code> may be present
within each <span title="concept-item">item</span> with the type
<code title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-class"><code>class</code></dfn></dt>
<dd>
<p>Gives the access classification of the information regarding
the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text with one of the following values:</p>
<ul class="brief">
<li><code title="">public</code></li>
<li><code title="">private</code></li>
<li><code title="">confidential</code></li>
</ul>
<p class="warning">This is merely advisory and cannot be
considered a confidentiality measure.</p>
<p>A single property with the name <code
title="md-vevent-class">class</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-comment"><code>comment</code></dfn></dt>
<dd>
<p>Gives a comment regarding the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>Any number of properties with the name <code
title="md-vevent-comment">comment</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-description"><code>description</code></dfn></dt>
<dd>
<p>Gives a detailed description of the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>A single property with the name <code
title="md-vevent-description">description</code> may be present
within each <span title="concept-item">item</span> with the type
<code title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-geo"><code>geo</code></dfn></dt>
<dd>
<p>Gives the geographical position of the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text and must match the following syntax:</p>
<ol>
<li>Optionally, either a U+002B PLUS SIGN character (+) or a
U+002D HYPHEN-MINUS character (-).</li>
<li>One or more digits in the range U+0030 DIGIT ZERO (0) to U+0039
DIGIT NINE (9).</li>
<li>Optionally*, a U+002E FULL STOP character (.) followed by one
or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
NINE (9).</li>
<li>A U+003B SEMICOLON character (;).</li>
<li>Optionally, either a U+002B PLUS SIGN character (+) or a
U+002D HYPHEN-MINUS character (-).</li>
<li>One or more digits in the range U+0030 DIGIT ZERO (0) to U+0039
DIGIT NINE (9).</li>
<li>Optionally*, a U+002E FULL STOP character (.) followed by one
or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
NINE (9).</li>
</ol>
<p>The optional components marked with an asterisk (*) should be
included, and should have six digits each.</p> <!-- iCalendar
actually limits the range to -91.0 < lat < 91.0; -181.0 < long <
181.0, which seems weird. It also gives special meanings to
+90/-90 lat, and +180 long. -->
<!-- copied from vcard (not icalendar!) -->
<p class="note">The value specifies latitude and longitude, in
that order (i.e., "LAT LON" ordering), in decimal degrees. The
longitude represents the location east and west of the prime
meridian as a positive or negative real number, respectively. The
latitude represents the location north and south of the equator as
a positive or negative real number, respectively.</p>
<p>A single property with the name <code
title="md-vevent-geo">geo</code> may be present within each <span
title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-location"><code>location</code></dfn></dt>
<dd>
<p>Gives the location of the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p> <!-- v2: support vcard here -->
<p>A single property with the name <code
title="md-vevent-location">location</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<!-- PRIORITY not included - always 0 - doesn't make sense for single events -->
<dt><dfn title="md-vevent-resources"><code>resources</code></dfn></dt>
<dd>
<p>Gives a resource that will be needed for the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p> <!-- v2: support vcard here -->
<p>Any number of properties with the name <code
title="md-vevent-resources">resources</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-status"><code>status</code></dfn></dt>
<dd>
<p>Gives the confirmation status of the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text with one of the following values:</p>
<ul class="brief">
<li><code title="">tentative</code></li>
<li><code title="">confirmed</code></li>
<li><code title="">cancelled</code></li> <!-- two Ls as per iCalendar spec -->
</ul>
<p>A single property with the name <code
title="md-vevent-status">status</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-summary"><code>summary</code></dfn></dt>
<dd>
<p>Gives a short summary of the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p>
<p>User agents should replace U+000A LINE FEED (LF) characters in
the <span title="concept-property-value">value</span> by U+0020
SPACE characters when using the value.</p>
<p>A single property with the name <code
title="md-vevent-summary">summary</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-dtend"><code>dtend</code></dfn></dt>
<dd>
<p>Gives the date and time by which the event ends.</p>
<p>If the property with the name <code
title="md-vevent-dtend">dtend</code> is present within an <span
title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>
that has a property with the name <code
title="md-vevent-dtstart">dtstart</code> whose value is a
<span>valid date string</span>, then the <span
title="concept-property-value">value</span> of the property with
the name <code title="md-vevent-dtend">dtend</code> must be text
that is a <span>valid date string</span> also. Otherwise, the
<span title="concept-property-value">value</span> of the property
must be text that is a <span>valid global date and time
string</span>.</p>
<p>In either case, the <span
title="concept-property-value">value</span> be later in time than
the value of the <code title="md-event-dtstart">dtstart</code>
property of the same <span title="concept-item">item</span>.</p>
<p class="note">The time given by the <code
title="md-vevent-dtend">dtend</code> property is not
inclusive. For day-long events, therefore, the <code
title="md-vevent-dtend">dtend</code> property's <span
title="concept-property-value">value</span> will be the day
<em>after</em> the end of the event.</p>
<p>A single property with the name <code
title="md-vevent-dtend">dtend</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>,
so long as that <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>
does not have a property with the name <code
title="md-vevent-duration">duration</code>.</p>
</dd>
<dt><dfn title="md-vevent-dtstart"><code>dtstart</code></dfn></dt>
<dd>
<p>Gives the date and time at which the event starts.</p>
<p>The <span title="concept-property-value">value</span> must be
text that is either a <span>valid date string</span> or a
<span>valid global date and time string</span>.</p>
<p>Exactly one property with the name <code
title="md-vevent-dtstart">dtstart</code> must be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-duration"><code>duration</code></dfn></dt>
<dd>
<p>Gives the date and time at which the event starts.</p>
<p>The <span title="concept-property-value">value</span> must be
text that is a <span>valid vevent duration string</span>.</p>
<p>The duration represented is the sum of all the durations
represented by integers in the value.</p>
<p>A single property with the name <code
title="md-vevent-duration">duration</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>,
so long as that <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>
does not have a property with the name <code
title="md-vevent-dtend">dtend</code>.</p>
</dd>
<dt><dfn title="md-vevent-transp"><code>transp</code></dfn></dt>
<dd>
<p>Gives whether the event is to be considered as consuming time
on a calendar, for the purpose of free-busy time searches.</p>
<p>The <span title="concept-property-value">value</span> must be
text with one of the following values:</p>
<ul class="brief">
<li><code title="">opaque</code></li>
<li><code title="">transparent</code></li>
</ul>
<p>A single property with the name <code
title="md-vevent-transp">transp</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<!-- ATTENDEE not included; iCalendar says MUST NOT be included in
published events -->
<dt><dfn title="md-vevent-contact"><code>contact</code></dfn></dt>
<dd>
<p>Gives the contact information for the event.</p>
<p>The <span title="concept-property-value">value</span> must be
text.</p> <!-- v2: support vcard here -->
<p>Any number of properties with the name <code
title="md-vevent-contact">contact</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<!-- ORGANIZER not included, as it is calendar-system-specific
(gives a CAL-ADDRESS value); use CONTACT instead -->
<!-- RECURRENCE-ID not included... unclear how to make it usefully
work here -->
<!-- RELATED-TO not included, as it only makes sense for complete
calendars -->
<dt><dfn title="md-vevent-url"><code>url</code></dfn></dt>
<dd>
<p>Gives a <span>URL</span> for the event.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>A single property with the name <code
title="md-vevent-url">url</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<!-- UID not included - use "itemid" -->
<dt><dfn title="md-vevent-exdate"><code>exdate</code></dfn></dt>
<dd>
<p>Gives a date and time at which the event does not occur despite
the recurrence rules.</p>
<p>The <span title="concept-property-value">value</span> must be
text that is either a <span>valid date string</span> or a
<span>valid global date and time string</span>.</p>
<p>Any number of properties with the name <code
title="md-vevent-exdate">exdate</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-exrule"><code>exrule</code></dfn></dt>
<dd>
<p>Gives a rule for finding dates and times at which the event
does not occur despite the recurrence rules.</p>
<p>The <span title="concept-property-value">value</span> must be
text that matches the RECUR value type defined in the iCalendar
specification. <a href="#refsRFC2445">[RFC2445]</a></p>
<p>Any number of properties with the name <code
title="md-vevent-exrule">exrule</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-rdate"><code>rdate</code></dfn></dt>
<dd>
<p>Gives a date and time at which the event recurs.</p>
<p>The <span title="concept-property-value">value</span> must be
text that is one of the following:
<ul>
<li>A <span>valid date string</span>.</li>
<li>A <span>valid global date and time string</span>.</li>
<li>A <span>valid global date and time string</span> followed by
a U+002F SOLIDUS character (/) followed by a second <span>valid
global date and time string</span> representing a later time.</li>
<li>A <span>valid global date and time string</span> followed by
a U+002F SOLIDUS character (/) followed by a <span>valid vevent
duration string</span>.</li>
</ul>
<p>Any number of properties with the name <code
title="md-vevent-rdate">rdate</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-rrule"><code>rrule</code></dfn></dt>
<dd>
<p>Gives a rule for finding dates and times at which the event
occurs.</p>
<p>The <span title="concept-property-value">value</span> must be
text that matches the RECUR value type defined in the iCalendar
specification. <a href="#refsRFC2445">[RFC2445]</a></p>
<p>Any number of properties with the name <code
title="md-vevent-rrule">rrule</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-created"><code>created</code></dfn></dt>
<dd>
<p>Gives the date and time at which the event information was first
created in a calendaring system.</p>
<p>The <span title="concept-property-value">value</span> must be
text that is a <span>valid global date and time string</span>.</p>
<p>A single property with the name <code
title="md-vevent-created">created</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<!-- DTSTAMP not included, it gets added when serialising -->
<dt><dfn title="md-vevent-last-modified"><code>last-modified</code></dfn></dt>
<dd>
<p>Gives the date and time at which the event information was last
modified in a calendaring system.</p>
<p>The <span title="concept-property-value">value</span> must be
text that is a <span>valid global date and time string</span>.</p>
<p>A single property with the name <code
title="md-vevent-last-modified">last-modified</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<dt><dfn title="md-vevent-sequence"><code>sequence</code></dfn></dt>
<dd>
<p>Gives a revision number for the event information.</p>
<p>The <span title="concept-property-value">value</span> must be
text that is a <span>valid non-negative integer</span>.</p>
<p>A single property with the name <code
title="md-vevent-sequence">sequence</code> may be present within
each <span title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>.</p>
</dd>
<!-- REQUEST-STATUS not included, calendaring system interop
feature -->
</dl>
<p>A string is a <dfn>valid vevent duration string</dfn> if it
matches the following pattern:</p>
<ol>
<li>A U+0050 LATIN CAPITAL LETTER P character (P).</li>
<li>One of the following:
<ul>
<li> A <span>valid non-negative integer</span> followed by a
U+0057 LATIN CAPITAL LETTER W character (W). The integer
represents a duration of that number of weeks. </li>
<li> At least one, and possible both in this order, of the
following:
<ol>
<li> A <span>valid non-negative integer</span> followed by a
U+0044 LATIN CAPITAL LETTER D character (D). The integer
represents a duration of that number of days. </li>
<li> A U+0054 LATIN CAPITAL LETTER T character (T) followed by
any one of the following, or the first and second of the
following in that order, or the second and third of the
following in that order, or all three of the following in this
order:
<ol>
<li> A <span>valid non-negative integer</span> followed by a
U+0048 LATIN CAPITAL LETTER H character (H). The integer
represents a duration of that number of hours. </li>
<li> A <span>valid non-negative integer</span> followed by a
U+004D LATIN CAPITAL LETTER M character (M). The integer
represents a duration of that number of minutes. </li>
<li> A <span>valid non-negative integer</span> followed by a
U+0053 LATIN CAPITAL LETTER S character (S). The integer
represents a duration of that number of seconds. </li>
</ol>
</ol>
</li>
</ul>
</li>
</ol>
<h5>Conversion to iCalendar</h5>
<p>Given a list of nodes <var title="">nodes</var> in a
<code>Document</code>, a user agent must run the following algorithm
to <dfn title="extracting vEvent data">extract any vEvent data
represented by those nodes</dfn>:</p>
<ol>
<li><p>If none of the nodes in <var title="">nodes</var> are <span
title="concept-item">items</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>,
then there is no vEvent data. Abort the algorithm, returning
nothing.</p></li>
<li><p>Let <var title="">output</var> be an empty string.</p></li>
<li><p><span>Add an iCalendar line</span> with the type "<code
title="">BEGIN</code>" and the value "<code
title="">VCALENDAR</code>" to <var title="">output</var>.</p></li>
<li><p><span>Add an iCalendar line</span> with the type "<code
title="">PRODID</code>" and the value equal to a
user-agent-specific string representing the user agent to <var
title="">output</var>.</p></li>
<li><p><span>Add an iCalendar line</span> with the type "<code
title="">VERSION</code>" and the value "<code title="">2.0</code>"
to <var title="">output</var>.</p></li>
<li>
<p>For each node <var title="">node</var> in <var
title="">nodes</var> that is an <span
title="concept-item">item</span> with the type <code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>,
run the following steps:</p>
<ol>
<li><p><span>Add an iCalendar line</span> with the type "<code
title="">BEGIN</code>" and the value "<code
title="">VEVENT</code>" to <var title="">output</var>.</p></li>
<li><p><span>Add an iCalendar line</span> with the type "<code
title="">DTSTAMP</code>" and a value consisting of an iCalendar
DATE-TIME string representing the current date and time, with the
annotation "<code title="">VALUE=DATE-TIME</code>", to <var
title="">output</var>. <a
href="#refsRFC2445">[RFC2445]</a></p></li>
<li><p>If the <span title="concept-item">item</span> has a
<span>global identifier</span>, <span>add an iCalendar
line</span> with the type "<code title="">UID</code>" and that
<span>global identifier</span> as the value to <var
title="">output</var>.</p></li>
<li>
<p>For each element <var title="">element</var> that is <span
title="the properties of an item">a property of the item</span>
<var title="">node</var>: for each name <var title="">name</var>
in <var title="">element</var>'s <span>property names</span>,
run the appropriate set of substeps from the following list:</p>
<dl>
<dt>If the property's <span
title="concept-property-value">value</span> is an <span
title="concept-item">item</span></dt>
<dd>
<p>Skip the property.</p>
</dd>
<dt>If <var title="">element</var> is a <code>time</code>
element</dt>
<dd>
<p>Let <var title="">value</var> be the result of stripping
all U+002D HYPHEN-MINUS (-) and U+003A COLON (:) characters
from the property's <span
title="concept-property-value">value</span>.</p>
<p>If the property's <span
title="concept-property-value">value</span> is a <span>valid
date string</span> then <span>add an iCalendar line</span>
with the type <var title="">name</var> and the value <var
title="">value</var> to <var title="">output</var>, with the
annotation "<code title="">VALUE=DATE</code>".</p>
<p>Otherwise, if the property's <span
title="concept-property-value">value</span> is a <span>valid
global date and time string</span> then <span>add an iCalendar
line</span> with the type <var title="">name</var> and the
value <var title="">value</var> to <var title="">output</var>,
with the annotation "<code
title="">VALUE=DATE-TIME</code>".</p>
<p>Otherwise skip the property.</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p><span>Add an iCalendar line</span> with the type <var
title="">name</var> and the value <var title="">value</var> to
<var title="">output</var>.</p>
</dd>
</dl>
</li>
<li><p><span>Add an iCalendar line</span> with the type "<code
title="">END</code>" and the value "<code title="">VEVENT</code>"
to <var title="">output</var>.</p></li>
</ol>
</li>
<li><p><span>Add an iCalendar line</span> with the type "<code
title="">END</code>" and the value "<code
title="">VCALENDAR</code>" to <var title="">output</var>.</p></li>
</ol>
<p>When the above algorithm says that the user agent is to <dfn>add
an iCalendar line</dfn> consisting of a type <var
title="">type</var>, a value <var title="">value</var>, and
optionally an annotation, to a string <var title="">output</var>, it
must run the following steps:</p>
<ol>
<li><p>Let <var title="">line</var> be an empty string.</p></li>
<li><p>Append <var title="">type</var>, <span>converted to
ASCII uppercase</span>, to <var title="">line</var>.</p></li>
<li>
<p>If there is an annotation:</p>
<ol>
<li><p>Append a U+003B SEMICOLON character (;) to <var
title="">line</var>.</p></li>
<li><p>Append the annotation to <var
title="">line</var>.</p></li>
</ol>
</li>
<li><p>Append a U+003A COLON character (:) to <var
title="">line</var>.</p></li>
<li><p>Prefix every U+005C REVERSE SOLIDUS character (\) in
<var title="">value</var> with another U+005C REVERSE SOLIDUS
character (\).</p></li>
<li><p>Prefix every U+002C COMMA character (,) in <var
title="">value</var> with a U+005C REVERSE SOLIDUS character
(\).</p></li>
<li><p>Prefix every U+003B SEMICOLON character (;) in <var
title="">value</var> with a U+005C REVERSE SOLIDUS character
(\).</p></li>
<li><p>Replace every U+000D CARRIAGE RETURN U+000A LINE FEED
character pair (CRLF) in <var title="">value</var> with a U+005C
REVERSE SOLIDUS character (\) followed by a U+006E LATIN SMALL
LETTER N character (n).</p></li>
<li><p>Replace every remaining U+000D CARRIAGE RETURN (CR) or
U+000A LINE FEED (LF) character in <var title="">value</var> with a
U+005C REVERSE SOLIDUS character (\) followed by a U+006E LATIN
SMALL LETTER N character (n).</p></li>
<li><p>Append <var title="">value</var> to <var
title="">line</var>.</p></li>
<li><p>Let <var title="">maximum length</var> be 75.</p></li>
<li>
<p>If and while <var title="">line</var> is longer than <var
title="">maximum length</var> Unicode code points long, run the
following substeps:</p>
<ol>
<li><p>Append the first <var title="">maximum length</var>
Unicode code points of <var title="">line</var> to <var
title="">output</var>.</p></li>
<li><p>Remove the first <var title="">maximum length</var>
Unicode code points from <var title="">line</var>.</p></li>
<li><p>Append a U+000D CARRIAGE RETURN character (CR) to <var
title="">output</var>.</p></li>
<li><p>Append a U+000A LINE FEED character (LF) to <var
title="">output</var>.</p></li>
<li><p>Append a U+0020 SPACE character to <var
title="">output</var>.</p></li>
<li><p>Let <var title="">maximum length</var> be 74.</p></li>
</ol>
</li>
<li><p>Append (what remains of) <var title="">line</var> to <var
title="">output</var>.</p></li>
<li><p>Append a U+000D CARRIAGE RETURN character (CR) to <var
title="">output</var>.</p></li>
<li><p>Append a U+000A LINE FEED character (LF) to <var
title="">output</var>.</p></li>
</ol>
<p class="note">This algorithm can generate invalid iCalendar
output, if the input does not conform to the rules described for the
<code
title="md-vevent">http://microformats.org/profile/hcalendar#vevent</code>
<span>item type</span> and <span title="defined property
name">defined property names</span>.</p> <!-- of course since
iCalendar doesn't define error handling, this is somewhat
problematic. -->
<h5>Examples</h5>
<!-- get more from http://www.ietf.org/rfc/rfc2445.txt -->
<div class="example">
<p>Here is an example of a page that uses the vEvent vocabulary to
mark up an event:</p>
<pre><body itemscope itemtype="http://microformats.org/profile/hcalendar#vevent">
...
<h1 itemprop="summary">Bluesday Tuesday: Money Road</h1>
...
<time itemprop="dtstart" datetime="2009-05-05T19:00:00Z">May 5th @ 7pm</time>
(until <time itemprop="dtend" datetime="2009-05-05T21:00:00Z">9pm</time>)
...
<a href="http://livebrum.co.uk/2009/05/05/bluesday-tuesday-money-road"
rel="bookmark" itemprop="url">Link to this page</a>
...
<p>Location: <span itemprop="location">The RoadHouse</span></p>
...
<p><input type=button value="Add to Calendar"
onclick="location = getCalendar(this)"></p>
...
<meta itemprop="description" content="via livebrum.co.uk">
</body></pre>
<p>The "<code title="">getCalendar()</code>" method could look like
this:</p>
<pre>function getCalendar(node) {
while (node && (!node.nodeScope || !node.itemType == 'http://microformats.org/profile/hcalendar#vevent'))
node = node.parentNode;
if (!node) {
alert('No event data found.');
return;
}
var stamp = new Date();
var stampString = '' + stamp.getUTCFullYear() + (stamp.getUTCMonth() + 1) + stamp.getUTCDate() + 'T' +
stamp.getUTCHours() + stamp.getUTCMinutes() + stamp.getUTCSeconds() + 'Z';
var calendar = 'BEGIN:VCALENDAR\r\nPRODID:HTML\r\nVERSION:2.0\r\nBEGIN:VEVENT\r\nDTSTAMP:' + stampString + '\r\n';
if (node.itemId)
calendar += 'UID:' + node.itemId + '\r\n';
for (var propIndex = 0; propIndex < node.properties.length; propIndex += 1) {
var prop = node.properties[propIndex];
var value = prop.itemValue;
var parameters = '';
if (prop.localName == 'time') {
value = value.replace(/[:-]/g, '');
if (prop.date && prop.time)
parameters = ';VALUE=DATE';
else
parameters = ';VALUE=DATE-TIME';
} else {
value = value.replace(/\\/g, '\\n');
value = value.replace(/;/g, '\\;');
value = value.replace(/,/g, \\,');
value = value.replace(/\n/g, '\\n');
}
for (var nameIndex = 0; nameIndex < prop.itemProp.length; nameIndex += 1) {
var name = prop.itemProp[nameIndex];
if (!name.match(':') && !name.match('.'))
calendar += name.toUpperCase() + parameters + ':' + value + '\r\n';
}
}
calendar += 'END:VEVENT\r\nEND:VCALENDAR\r\n';
return 'data:text/calendar;component=vevent,' + encodeURI(calendar);
}</pre>
<p>The same page could offer some markup, such as the following,
for copy-and-pasting into blogs:</p>
<pre><div itemscope itemtype="http://microformats.org/profile/hcalendar#vevent">
<p>I'm going to
<strong itemprop="summary">Bluesday Tuesday: Money Road</strong>,
<time itemprop="dtstart" datetime="2009-05-05T19:00:00Z">May 5th at 7pm</time>
to <time itemprop="dtend" content="2009-05-05T21:00:00Z">9pm</time>,
at <span itemprop="location">The RoadHouse</span>!</p>
<p><a href="http://livebrum.co.uk/2009/05/05/bluesday-tuesday-money-road"
itemprop="url">See this event on livebrum.co.uk</a>.</p>
<meta itemprop="description" content="via livebrum.co.uk">
</div></pre>
</div>
<!--END vEvent-->
<h4>Licensing works</h4>
<!--END vocabs--><!--END complete-->
<!--START work-->
<h4 class="no-num no-toc">Table of contents</h4>
<!--toc-->
<hr>
<h5>The vocabulary</h5>
<p>This section defines a microdata vocabulary. <a
href="#refsHTML5">[HTML5]</a></p>
<!--START vocabs--><!--START complete-->
<p>An item with the <span>item type</span> <dfn
title="md-work"><code>http://n.whatwg.org/work</code></dfn>
represents a work (e.g. an article, an image, a video, a song,
etc). This type is primarily intended to allow authors to include
licensing information for works.</p>
<p>The following are the type's <span title="defined property
name">defined property names</span>.</p>
<dl>
<dt><dfn title="md-work-work"><code>work</code></dfn></dt>
<dd>
<p>Identifies the work being described.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>Exactly one property with the name <code
title="md-work-work">work</code> must be present within each <span
title="concept-item">item</span> with the type <code
title="md-work">http://n.whatwg.org/work</code>.</p>
</dd>
<dt><dfn title="md-work-title"><code>title</code></dfn></dt>
<dd>
<p>Gives the name of the work.</p>
<p>A single property with the name <code
title="md-work-title">title</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-work">http://n.whatwg.org/work</code>.</p>
</dd>
<dt><dfn title="md-work-author"><code>author</code></dfn></dt>
<dd>
<p>Gives the name or contact information of one of the authors or
creators of the work.</p>
<p>The <span title="concept-property-value">value</span> must be
either an <span title="concept-item">item</span> with the type
<code
title="md-vcard">http://microformats.org/profile/hcard</code>, or
text.</p>
<p>Any number of properties with the name <code
title="md-work-author">author</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-work">http://n.whatwg.org/work</code>.</p>
</dd>
<dt><dfn title="md-work-license"><code>license</code></dfn></dt>
<dd>
<p>Identifies one of the licenses under which the work is
available.</p>
<p>The <span title="concept-property-value">value</span> must be
an <span>absolute URL</span>.</p>
<p>Any number of properties with the name <code
title="md-work-license">license</code> may be present within each
<span title="concept-item">item</span> with the type <code
title="md-work">http://n.whatwg.org/work</code>.</p>
</dd>
</dl>
<h5>Conversion to RDF</h5>
<p>For the purposes of RDF processors, blank nodes that are the
subject of a triple with the predicate "<code
title="">http://www.w3.org/1999/xhtml/microdata#http%3A%2F%2Fn.whatwg.org%2Fwork%23%3Awork</code>"
and the object <var title="">s</var> must be treated as if the node
was identified by <var title="">s</var>.</p>
<p>For the purposes of RDF processors, the predicate "<code
title="">http://www.w3.org/1999/xhtml/microdata#http%3A%2F%2Fn.whatwg.org%2Fwork%23%3Atitle</code>"
must be considered equivalent to the predicate "<code
title="">http://purl.org/dc/elements/1.1/title</code>".
<p>For the purposes of RDF processors, the predicate "<code
title="">http://www.w3.org/1999/xhtml/microdata#http%3A%2F%2Fn.whatwg.org%2Fwork%23%3Aauthor</code>"
must be considered equivalent to the predicate "<code
title="">http://creativecommons.org/ns#attributionName</code>".
<p>For the purposes of RDF processors, the predicate "<code
title="">http://www.w3.org/1999/xhtml/microdata#http%3A%2F%2Fn.whatwg.org%2Fwork%23%3Alicense</code>"
must be considered equivalent to the predicate "<code
title="">http://www.w3.org/1999/xhtml/vocab#license</code>".
<h5>Examples</h5>
<div class="example">
<p>This example shows an embedded image entitled <cite>My
Pond</cite>, licensed under the Creative Commons Attribution-Share
Alike 3.0 United States License and the MIT license
simultaneously.</p>
<pre><figure <strong>itemscope itemtype="http://n.whatwg.org/work"</strong>>
<dd><img <strong>itemprop="work"</strong> src="mypond.jpeg">
<dt>
<p><cite <strong>itemprop="title"</strong>>My Pond</cite></p>
<p><small>Licensed under the <a <strong>itemprop="license"</strong>
href="http://creativecommons.org/licenses/by-sa/3.0/us/">Creative
Commons Attribution-Share Alike 3.0 United States License</a>
and the <a <strong>itemprop="license"</strong>
href="http://www.opensource.org/licenses/mit-license.php">MIT
license</a>.</small>
</figure></pre>
</div>
<!--END work-->
<!--END vocabs-->
<!--START html--><!--START html5-->
<div class="impl">
<h3>Converting HTML to other formats</h3>
<h4>JSON</h4>
<p>Given a list of nodes <var title="">nodes</var> in a
<code>Document</code>, a user agent must run the following algorithm
to <dfn title="extracting JSON">extract the microdata from those
nodes into a JSON form</dfn>:</p>
<ol>
<li><p>Let <var title="">result</var> be an empty object.</p></li>
<li><p>Let <var title="">items</var> be an empty array.</p></li>
<li><p>For each <var title="">node</var> in <var
title="">nodes</var>, check if the element is a <span
title="top-level microdata items">top-level microdata item</span>,
and if it is then <span>get the object</span> for that element and
add it to <var title="">items</var>.</p></li>
<li><p>Add an entry to <var title="">result</var> called "<code
title="">items</code>" whose value is the array <var
title="">items</var>.</p></li>
<li><p>Return the result of serializing <var title="">result</var>
to JSON.</p></li>
</ol>
<p>When the user agent is to <dfn>get the object</dfn> for an item
<var title="">item</var>, it must run the following substeps:</p>
<ol>
<li><p>Let <var title="">result</var> be an empty object.</p></li>
<li><p>If the <var title="">item</var> has an <span>item
type</span>, add an entry to <var title="">result</var> called
"<code title="">type</code>" whose value is the <span>item
type</span> of <var title="">item</var>.</p></li>
<li><p>If the <var title="">item</var> has an <span>global
identifier</span>, add an entry to <var title="">result</var>
called "<code title="">id</code>" whose value is the <span>global
identifier</span> of <var title="">item</var>.</p></li>
<li><p>Let <var title="">properties</var> be an empty
object.</p></li>
<li>
<p>For each element <var title="">element</var> that has one or
more <span>property names</span> and is one of <span title="the
properties of an item">the properties of the item</span> <var
title="">item</var>, in the order those elements are given by the
algorithm that returns <span>the properties of an item</span>, run
the following substeps:</p>
<ol>
<li><p>Let <var title="">value</var> be the <span
title="concept-property-value">property value</span> of <var
title="">element</var>.</p></li>
<li><p>If <var title="">value</var> is an <span
title="concept-item">item</span>, then <span>get the
object</span> for <var title="">value</var>, and then replace
<var title="">value</var> with the object returned from those
steps.</p></li>
<li>
<p>For each name <var title="">name</var> in <var
title="">element</var>'s <span>property names</span>, run the
following substeps:</p>
<ol>
<li><p>If there is no entry named <var title="">name</var> in
<var title="">properties</var>, then add an entry named <var
title="">name</var> to <var title="">properties</var> whose
value is an empty array.</p></li>
<li><p>Append <var title="">value</var> to the entry named <var
title="">name</var> in <var title="">properties</var>.</p></li>
</ol>
</li>
</ol>
</li>
<li><p>Add an entry to <var title="">result</var> called "<code
title="">properties</code>" whose value is the object <var
title="">properties</var>.</p></li>
<li><p>Return <var title="">result</var>.</p></li>
</ol>
<h4>RDF</h4>
<p>To convert a <code>Document</code> to RDF, a user agent must run
the following algorithm:</p>
<ol>
<li>
<p>If <span>the <code>title</code> element</span> is not null,
then generate the following triple:</p>
<dl class="triple">
<dt>subject <dd> <span>the document's current address</span>
<dt>predicate <dd> <code title="">http://purl.org/dc/terms/title</code>
<dt>object <dd> the concatenation of the data of all the child <span title="text node">text nodes</span> of <span>the <code>title</code> element</span>, in <span>tree order</span>, as a plain literal, with the language information set from the <span>language</span> of <span>the <code>title</code> element</span>, if it is not unknown.
</dl>
</li>
<li>
<p>For each <code>a</code>, <code>area</code>, and
<code>link</code> element in the <code>Document</code>, run these
substeps:</p>
<ol>
<li><p>If the element does not have a <code title="">rel</code>
attribute, then skip this element.</p></li>
<li><p>If the element does not have an <code title="">href</code>
attribute, then skip this element.</p></li>
<li><p>If <span title="resolve a URL">resolving</span> the
element's <code title="">href</code> attribute relative to the
element is not successful, then skip this element.</p></li>
<li><p>Otherwise, <span title="split a string on spaces">split
the value of the element's <code title="">rel</code> attribute on
spaces</span>, obtaining <var title="">list of tokens</var>.</p></li>
<li><p><span title="converted to ASCII lowercase">Convert each token in
<var title="">list of tokens</var> to ASCII lowercase</span>.</p></li>
<li><p>If <var title="">list of tokens</var> contains more than
one instance of the token <code title="rel-up">up</code>, then
remove all such tokens.</p></li>
<li><p>Coalesce duplicate tokens in <var title="">list of
tokens</var>.</p></li>
<li><p>If <var title="">list of tokens</var> contains both the
tokens <code title="rel-alternate">alternate</code> and <code
title="rel-stylesheet">stylesheet</code>, then remove them both
and replace them with the single (uppercase) token <code
title="">ALTERNATE-STYLESHEET</code>.</p></li>
<li>
<p>For each token <var title="">token</var> in <var
title="">list of tokens</var> that contains no U+003A COLON
characters (:), generate the following triple:</p>
<dl class="triple">
<dt>subject <dd> <span>the document's current address</span>
<dt>predicate <dd> the concatenation of the string "<code title="">http://www.w3.org/1999/xhtml/vocab#</code>" and <var title="">token</var>, with any characters in <var title="">token</var> that are not valid in the <ifragment> production of the IRI syntax being %-escaped <a href="#refsRFC3987">[RFC3987]</a>
<dt>object <dd> the <span>absolute URL</span> that results from <span title="resolve a URL">resolving</span> the value of the element's <code title="">href</code> attribute relative to the element
</dl>
<p>For each token <var title="">token</var> in <var
title="">list of tokens</var> that is an <span>absolute
URL</span>, generate the following triple:</p>
<dl class="triple">
<dt>subject <dd> <span>the document's current address</span>
<dt>predicate <dd> <var title="">token</var>
<dt>object <dd> the <span>absolute URL</span> that results from <span title="resolve a URL">resolving</span> the value of the element's <code title="">href</code> attribute relative to the element
</dl>
</li>
</ol>
</li>
<li>
<p>For each <code>meta</code> element in the <code>Document</code>
that has a <code title="attr-meta-name">name</code> attribute and
a <code title="attr-meta-content">content</code> attribute, if the
value of the <code title="attr-meta-name">name</code> attribute
contains no U+003A COLON characters (:), generate the following
triple:</p>
<dl class="triple">
<dt>subject <dd> <span>the document's current address</span>
<dt>predicate <dd> the concatenation of the string "<code title="">http://www.w3.org/1999/xhtml/vocab#</code>" and the value of the element's <code title="attr-meta-name">name</code> attribute, <span>converted to ASCII lowercase</span>, with any characters in the value that are not valid in the <ifragment> production of the IRI syntax being %-escaped <a href="#refsRFC3987">[RFC3987]</a>
<dt>object <dd> the value of the element's <code title="attr-meta-content">content</code> attribute, as a plain literal, with the language information set from the <span>language</span> of the element, if it is not unknown
</dl>
<p>For each <code>meta</code> element in the <code>Document</code>
that has a <code title="attr-meta-name">name</code> attribute and
a <code title="attr-meta-content">content</code> attribute, if the
value of the <code title="attr-meta-name">name</code> attribute is
an <span>absolute URL</span>, generate the following triple:</p>
<dl class="triple">
<dt>subject <dd> <span>the document's current address</span>
<dt>predicate <dd> the value of the element's <code title="attr-meta-name">name</code> attribute
<dt>object <dd> the value of the element's <code title="attr-meta-content">content</code> attribute, as a plain literal, with the language information set from the <span>language</span> of the element, if it is not unknown
</dl>
</li>
<li>
<p>For each <code>blockquote</code> and <code>q</code> element in
the <code>Document</code> that has a <code title="">cite</code>
attribute that <span title="resolve a url">resolves</span>
successfully relative to the element, generate the following
triple:</p>
<dl class="triple">
<dt>subject <dd> <span>the document's current address</span>
<dt>predicate <dd> <code title="">http://purl.org/dc/terms/source</code>
<dt>object <dd> the <span>absolute URL</span> that results from <span title="resolve a URL">resolving</span> the value of the element's <code title="">cite</code> attribute relative to the element
</dl>
</li>
<li>
<p>For each element that is also a <span title="top-level
microdata items">top-level microdata item</span>, run the
following steps:</p>
<ol>
<li>
<p><span title="generate the triples for an item">Generate the
triples for the item</span>. Let <var title="">item</var> be the
subject returned.</p>
</li>
<li>
<p>Generate the following triple:</p>
<dl class="triple">
<dt>subject <dd> <span>the document's current address</span>
<dt>predicate <dd> <code title="">http://www.w3.org/1999/xhtml/microdata#item</code>
<dt>object <dd> <var title="">item</var>
</dl>
</li>
</ol>
</li>
</ol>
<p>When the user agent is to <dfn>generate the triples for an
item</dfn> <var title="">item</var>, it must follow the following
steps:</p>
<ol>
<li><p>If <var title="">item</var> has a <span>global
identifier</span> and that <span>global identifier</span> is an
<span>absolute URL</span>, let <var title="">subject</var> be that
<span>global identifier</span>. Otherwise, let <var
title="">subject</var> be a new blank node.</p></li>
<li><p>If <var title="">item</var> has an <span>item type</span>
and that <span>item type</span> is an <span>absolute URL</span>,
let <var title="">type</var> be that <span>item
type</span>. Otherwise, let <var title="">type</var> be the empty
string.</p></li>
<li>
<p>If <var title="">type</var> is not the empty string, generate
the following triple:</p>
<dl class="triple">
<dt>subject <dd> <var title="">subject</var>
<dt>predicate <dd> <code title="">http://www.w3.org/1999/02/22-rdf-syntax-ns#type</code>
<dt>object <dd> <var title="">type</var>
</dl>
</li>
<li>
<p>For each element <var title="">element</var> that has one or
more <span>property names</span> and is one of <span title="the
properties of an item">the properties of the item</span> <var
title="">item</var>, in the order those elements are given by the
algorithm that returns <span>the properties of an item</span>, run
the following substeps:</p>
<ol>
<li><p>Let <var title="">value</var> be the <span
title="concept-property-value">property value</span> of <var
title="">element</var>.</p></li>
<li><p>If <var title="">value</var> is an <span
title="concept-item">item</span>, then <span title="generate the
triples for an item">generate the triples</span> for <var
title="">value</var>, and then replace <var title="">value</var>
with the subject returned from those steps.</p></li>
<!-- could support <time> here somehow, though we'd have to
reserialise it, check if the <time> was valid, check if it had a
date, a time, a timezone, etc. -->
<li><p>Otherwise, if <var title="">element</var> is not one of
the <span>URL property elements</span>, let <var
title="">value</var> be a plain literal, with the language
information set from the <span>language</span> of the element, if
it is not unknown.</p></li>
<li>
<p>For each name <var title="">name</var> in <var
title="">element</var>'s <span>property names</span>, run the
appropriate substeps from the following list:</p>
<dl>
<dt>If <var title="">name</var> is an <span>absolute
URL</span></dt>
<dd>
<p>Generate the following triple:</p>
<dl class="triple">
<dt>subject <dd> <var title="">subject</var>
<dt>predicate <dd> <var title="">name</var>
<dt>object <dd> <var title="">value</var>
</dl>
</dd>
<dt>If <var title="">name</var> contains no U+003A COLON
character (:)</dt>
<dd>
<ol>
<li><p>If <var title="">type</var> is the empty string, then
abort these substeps.</p></li>
<li><p>Let <var title="">predicate</var> have the same value
as <var title="">type</var>.</p></li>
<li><p>If <var title="">predicate</var> does not contain a
U+0023 NUMBER SIGN character (#), then append a U+0023 NUMBER
SIGN character (#) to <var title="">predicate</var>.</p></li>
<li><p>Append a U+003A COLON character (:) to <var
title="">predicate</var>.</p></li> <!-- has to be something
not in /name/, so ":", so that a different type/name
combination couldn't generate the same string -->
<li><p>Append the value of <var title="">name</var> to <var
title="">predicate</var>, with any characters in <var
title="">name</var> that are not valid in the <ifragment>
production of the IRI syntax being %-escaped.</p></li>
<li>
<p>Generate the following triple:</p>
<dl class="triple">
<dt>subject <dd> <var title="">subject</var>
<dt>predicate <dd> the concatenation of the string "<code title="">http://www.w3.org/1999/xhtml/microdata#</code>" and <var title="">predicate</var>, with any characters in <var title="">predicate</var> that are not valid in the <ifragment> production of the IRI syntax being %-escaped <a href="#refsRFC3987">[RFC3987]</a>
<dt>object <dd> <var title="">value</var>
</dl>
</li>
</ol>
</dd>
</dl>
</li>
</ol>
</li>
<li><p>Return <var title="">subject</var>.</p></li>
</ol>
<h4>Atom</h4>
<p>Given a <code>Document</code> <var title="">source</var>, a user
agent must run the following algorithm to <dfn title="extracting
Atom">extract an Atom feed</dfn>:</p>
<ol>
<li><p>If the <code>Document</code> <var title="">source</var> does
not contain any <code>article</code> elements, then return nothing
and abort these steps. This algorithm can only be used with
documents that contain distinct articles.</p>
<li><p>Let <var title="">R</var> be an empty <span title="XML
documents">XML</span> <code>Document</code> object whose <span
title="the document's address">address</span> is user-agent
defined.</p></li>
<li><p>Append a <code title="">feed</code> element in the
<span>Atom namespace</span> to <var title="">R</var>.</p></li>
<li>
<p>For each <code>meta</code> element with a <code
title="attr-meta-name">name</code> attribute and a <code
title="attr-meta-content">content</code> attribute and whose <code
title="attr-meta-name">name</code> attribute's value is <code
title="meta-author">author</code>, run the following substeps:</p>
<ol>
<li><p>Append an <code title="">author</code> element in the
<span>Atom namespace</span> to the root element of <var
title="">R</var>.</p></li>
<li><p>Append a <code title="">name</code> element in the
<span>Atom namespace</span> to the element created in the
previous step.</p>
<li><p>Append a text node whose data is the value of the
<code>meta</code> element's <code
title="attr-meta-content">content</code> attribute to the element
created in the previous step.</p></li>
</ol>
<!-- could use vCards instead, and get <atom:email> and <atom:uri>
elements out of this instead of just <atom:name> -->
</li>
<li>
<p>If there is a <code>link</code> element whose <code
title="attr-link-rel">rel</code> attribute's value includes the
keyword <code title="rel-icon">icon</code>, and that element also
has an <code title="attr-link-href">href</code> attribute whose
value successfully <span title="resolve a url">resolves</span>
relative to the <code>link</code> element, then append an <code
title="">icon</code> element in the <span>Atom namespace</span> to
the root element of <var title="">R</var> whose contents is a text
node with its data set to the <span>absolute URL</span> resulting
from <span title="resolve a url">resolving</span> the value of the
<code title="attr-link-href">href</code> attribute.</p>
<!-- could check ratio, could check type... -->
</li>
<li>
<p>Append an <code title="">id</code> element in the <span>Atom
namespace</span> to the root element of <var title="">R</var>
whose contents is a text node with its data set to <span>the
document's current address</span>.</p>
</li>
<li>
<p>Optionally: Let <var title="">x</var> be a <code
title="">link</code> element in the <span>Atom
namespace</span>. Add a <code title="">rel</code> attribute whose
value is the string "<code title="">self</code>" to <var
title="">x</var>. Append a text node with its data set to the
(user-agent-defined) <span title="the document's
address">address</span> of <var title="">R</var> to <var
title="">x</var>. Append <var title="">x</var> to the root element
of <var title="">R</var>.</p>
<p class="note">This step would be skipped when the document <var
title="">R</var> has no convenient <span title="the document's
address">address</span>. The presence of the <code
title="">rel="self"</code> link is a "should"-level requirement in
the Atom specification.</p>
</li>
<li>
<p>Let <var title="">x</var> be a <code title="">link</code>
element in the <span>Atom namespace</span>. Add a <code
title="">rel</code> attribute whose value is the string "<code
title="">alternate</code>" to <var title="">x</var>. If the
document being converted is an <span title="HTML documents">HTML
document</span>, add a <code title="">type</code> attribute whose
value is the string "<code>text/html</code>" to <var
title="">x</var>. Otherwise, the document being converted is an
<span title="XML documents">XML document</span>; add a <code
title="">type</code> attribute whose value is the string
"<code>application/xhtml+xml</code>" to <var
title="">x</var>. Append a text node with its data set to
<span>the document's current address</span> to <var
title="">x</var>. Append <var title="">x</var> to the root element
of <var title="">R</var>.</p>
</li>
<li><p>Let <var title="">subheading text</var> be the empty
string.</p></li>
<li><p>Let <var title="">heading</var> be the first element of
<span>heading content</span> whose nearest ancestor of
<span>sectioning content</span> is <span>the body
element</span>, if any, or null if there is none.</p></li>
<li>
<p>Take the appropriate action from the following list, as
determined by the type of the <var title="">heading</var>
element:</p>
<dl>
<dt>If <var title="">heading</var> is null</dt>
<dd>
<p>Let <var title="">heading text</var> be the
<code>textContent</code> of <span>the <code>title</code>
element</span>, if there is one, or the empty string
otherwise.</p>
</dd>
<dt>If <var title="">heading</var> is a <code>hgroup</code> element</dt>
<dd>
<p>If <var title="">heading</var> contains no child
<code>h1</code>–<code>h6</code> elements, let <var
title="">heading text</var> be the empty string.</p>
<p>Otherwise, let <var title="">headings list</var> be a list of
all the <code>h1</code>–<code>h6</code> element children
of <var title="">heading</var>, sorted first by descending
<span>rank</span> and then in <span>tree order</span> (so
<code>h1</code>s first, then <code>h2</code>s, etc, with each
group in the order they appear in the document). Then, let <var
title="">heading text</var> be the <code>textContent</code> of
the first entry in <var title="">headings list</var>, and if
there are multiple entries, let <var title="">subheading
text</var> be the <code>textContent</code> of the second entry
in <var title="">headings list</var>.</p>
</dd>
<dt>If <var title="">heading</var> is an <code>h1</code>–<code>h6</code> element</dt>
<dd>
<p>Let <var title="">heading text</var> be the
<code>textContent</code> of <var title="">heading</var>.</p>
</dd>
</dl>
</li>
<li>
<p>Append a <code title="">title</code> element in the <span>Atom
namespace</span> to the root element of <var title="">R</var>
whose contents is a text node with its data set to <var
title="">heading text</var>.</p>
</li>
<li>
<p>If <var title="">subheading text</var> is not the empty string,
append a <code title="">subtitle</code> element in the <span>Atom
namespace</span> to the root element of <var title="">R</var>
whose contents is a text node with its data set to <var
title="">subheading text</var>.</p>
</li>
<li><p>Let <var title="">global update date</var> have no
value.</p></li>
<li>
<p>For each <code>article</code> element <var
title="">article</var> that does not have an ancestor
<code>article</code> element, run the following steps:</p>
<ol>
<li><p>Let <var title="">E</var> be an <code
title="">entry</code> element in the <span>Atom namespace</span>,
and append <var title="">E</var> to the root element of <var
title="">R</var>.</p></li>
<li><p>Let <var title="">heading</var> be the first element of
<span>heading content</span> whose nearest ancestor of
<span>sectioning content</span> is <var title="">article</var>,
if any, or null if there is none.</p></li>
<li>
<p>Take the appropriate action from the following list, as
determined by the type of the <var title="">heading</var>
element:</p>
<dl>
<dt>If <var title="">heading</var> is null</dt>
<dd>
<p>Let <var title="">heading text</var> be the empty
string.</p>
</dd>
<dt>If <var title="">heading</var> is a <code>hgroup</code> element</dt>
<dd>
<p>If <var title="">heading</var> contains no child
<code>h1</code>–<code>h6</code> elements, let <var
title="">heading text</var> be the empty string.</p>
<p>Otherwise, let <var title="">headings list</var> be a list
of all the <code>h1</code>–<code>h6</code> element
children of <var title="">heading</var>, sorted first by
descending <span>rank</span> and then in <span>tree
order</span> (so <code>h1</code>s first, then
<code>h2</code>s, etc, with each group in the order they
appear in the document). Then, let <var title="">heading
text</var> be the <code>textContent</code> of the first entry
in <var title="">headings list</var>.</p>
</dd>
<dt>If <var title="">heading</var> is an <code>h1</code>–<code>h6</code> element</dt>
<dd>
<p>Let <var title="">heading text</var> be the
<code>textContent</code> of <var title="">heading</var>.</p>
</dd>
</dl>
</li>
<li>
<p>Append a <code title="">title</code> element in the
<span>Atom namespace</span> to <var title="">E</var> whose
contents is a text node with its data set to <var
title="">heading text</var>.</p>
</li>
<!-- <atom:author> is required either at the feed level (above)
or the entry level (here) but we don't provide it -->
<li>
<p>Clone <var title="">article</var> and its descendants into an
environment that has <span title="concept-bc-noscript">scripting
disabled</span>, has no <span title="plugin">plugins</span>, and
fails any attempt to <span title="fetch">fetch</span> any
resources. Let <var title="">cloned article</var> be the
resulting clone <code>article</code> element.</p>
</li>
<li>
<p>Remove from the subtree rooted at <var title="">cloned
article</var> any <code>article</code> elements other than the
<var title="">cloned article</var> itself, any
<code>header</code>, <code>footer</code>, or <code>nav</code>
elements whose nearest ancestor of <span>sectioning
content</span> is the <var title="">cloned article</var>, and
the first element of <span>heading content</span> whose nearest
ancestor of <span>sectioning content</span> is the <var
title="">cloned article</var>, if any.</p>
</li>
<li>
<p>If <var title="">cloned article</var> contains any
<code>ins</code> or <code>del</code> elements with <code
title="attr-mod-datetime">datetime</code> attributes whose
values <span title="parse a global date and time string">parse
as global date and time strings</span> without errors, then let
<var title="">update date</var> be the value of the <code
title="attr-mod-datetime">datetime</code> attribute that parses
to the newest <span title="concept-datetime">global date and
time</span>.</p>
<p>Otherwise, let <var title="">update date</var> have no
value.</p>
<p class="note">This value is used below; it is calculated here
because in certain cases the next step mutates the <var
title="">cloned article</var>.</p>
</li>
<li>
<p>If the document being converted is an <span title="HTML
documents">HTML document</span>, then: Let <var title="">x</var>
be a <code title="">content</code> element in the <span>Atom
namespace</span>. Add a <code title="">type</code> attribute
whose value is the string "<code title="">html</code>" to <var
title="">x</var>. Append a text node with its data set to the
result of running the <span>HTML fragment serialization
algorithm</span> on <var title="">cloned article</var> to <var
title="">x</var>. Append <var title="">x</var> to <var
title="">E</var>.</p>
<p>Otherwise, the document being converted is an <span
title="XML documents">XML document</span>: Let <var
title="">x</var> be a <code title="">content</code> element in
the <span>Atom namespace</span>. Add a <code
title="">type</code> attribute whose value is the string "<code
title="">xml</code>" to <var title="">x</var>. Append a
<code>div</code> element to <var title="">x</var>. Move all the
child nodes of the <var title="">cloned article</var> node to
that <code>div</code> element, preserving their relative
order. Append <var title="">x</var> to <var
title="">E</var>.</p>
</li>
<li>
<p>Establish the value of <var title="">id</var> and <var
title="">has-alternate</var> from the first of the following to
apply:</p>
<dl>
<dt>If the <var title="">article</var> node has a descendant
<code>a</code> or <code>area</code> element with an <code
title="attr-hyperlink-href">href</code> attribute that
successfully <span title="resolve a url">resolves</span>
relative to that descendant and a <code
title="attr-a-rel">rel</code> attribute whose value includes
the <code title="rel-bookmark">bookmark</code> keyword</dt>
<dd>Let <var title="">id</var> be the <span>absolute URL</span>
resulting from <span title="resolve a url">resolving</span> the
value of the <code title="attr-hyperlink-href">href</code>
attribute of the first such <code>a</code> or <code>area</code>
element, relative to the element. Let <var
title="">has-alternate</var> be true.</dd>
<dt>If the <var title="">article</var> node has an <code
title="attr-id">id</code> attribute</dt>
<dd>Let <var title="">id</var> be <span>the document's current
address</span>, with the fragment identifier (if any) removed,
and with a new fragment identifier specified, consisting of the
value of the <var title="">article</var> element's <code
title="attr-id">id</code> attribute. Let <var
title="">has-alternate</var> be false.</dd>
<dt>Otherwise</dt>
<dd>Let <var title="">id</var> be a user-agent-defined
undereferenceable yet globally unique <span title="valid
URL">valid</span> <span>absolute URL</span>. The same
<span>absolute URL</span> should be generated for each run of
this algorithm when given the same input. Let <var
title="">has-alternate</var> be false.</dd>
</dl>
</li>
<li>
<p>Append an <code title="">id</code> element in the <span>Atom
namespace</span> to <var title="">E</var> whose contents is a
text node with its data set to <var title="">id</var>.</p>
</li>
<li>
<p>If <var title="">has-alternate</var> is true: Let <var
title="">x</var> be a <code title="">link</code> element in the
<span>Atom namespace</span>. Add a <code title="">rel</code>
attribute whose value is the string "<code
title="">alternate</code>" to <var title="">x</var>. Append a
text node with its data set to <var title="">id</var> to <var
title="">x</var>. Append <var title="">x</var> to <var
title="">E</var>.</p>
</li>
<li>
<p>If <var title="">article</var> has a <code>time</code>
element descendant that has a <code
title="attr-time-pubdate">pubdate</code> attribute and whose
nearest ancestor <code>article</code> element is <var
title="">article</var>, and the first such element's <span
title="concept-time-date">date</span> is not unknown, then run
the following substeps, with <var title="">e</var> being the
first such element:</p>
<ol>
<li><p>Let <var title="">datetime</var> be a <span
title="concept-datetime">global date and time</span> whose date
component is the <span title="concept-time-date">date</span> of
<var title="">e</var>.</p></li>
<li><p>If <var title="">e</var>'s <span
title="concept-time-time">time</span> and <span
title="concept-time-timezone">time-zone offset</span> are not
unknown, then let <var title="">datetime</var>'s time and
time-zone offset components be the <span
title="concept-time-time">time</span> and <span
title="concept-time-timezone">time-zone offset</span> of <var
title="">e</var>. Otherwise, let them be midnight and no offset
respectively ("<code title="">00:00Z</code>").</p></li>
<li><p>Let <var title="">publication date</var> be the
<span>best representation of the global date and time
string</span> <var title="">datetime</var>.</p></li>
</ol>
<p>Otherwise, let <var title="">publication date</var> have no
value.</p>
</li>
<li>
<p>If <var title="">update date</var> has no value but <var
title="">publication date</var> does, then let <var
title="">update date</var> have the value of <var
title="">publication date</var>.</p>
<p>Otherwise, if <var title="">publication date</var> has no
value but <var title="">update date</var> does, then let <var
title="">publication date</var> have the value of <var
title="">update date</var>.</p>
</li>
<li>
<p>If <var title="">update date</var> has a value, and <var
title="">global update date</var> has no value or is less recent
than <var title="">update date</var>, then let <var
title="">global update date</var> have the value of <var
title="">update date</var>.</p>
</li>
<li>
<p>If <var title="">publication date</var> and <var
title="">update date</var> both still have no value, then let
them both value a value that is a <span>valid global date and
time string</span> representing the <span
title="concept-datetime">global date and time</span> of the
moment that this algorithm was invoked.</p>
</li>
<li>
<p>Append an <code title="">published</code> element in the
<span>Atom namespace</span> to <var title="">E</var> whose
contents is a text node with its data set to <var
title="">publication date</var>.</p>
</li>
<li>
<p>Append an <code title="">updated</code> element in the
<span>Atom namespace</span> to <var title="">E</var> whose
contents is a text node with its data set to <var
title="">update date</var>.</p>
</li>
</ol>
</li>
<li>
<p>If <var title="">global update date</var> has no value, then
let it have a value that is a <span>valid global date and time
string</span> representing the <span
title="concept-datetime">global date and time</span> of the date
and time of the <code>Document</code>'s source file's last
modification, if it is known, or else of the moment that this
algorithm was invoked.</p>
</li>
<li>
<p>Insert an <code title="">updated</code> element in the
<span>Atom namespace</span> into the root element of <var
title="">R</var> before the first <code title="">entry</code> in
the <span>Atom namespace</span> whose contents is a text node with
its data set to <var title="">global update date</var>.</p>
</li>
<li><p>Return the Atom document <var title="">R</var>.</p></li>
</ol>
<p>The <dfn>Atom namespace</dfn> is: <code>http://www.w3.org/2005/Atom</code></p>
</div>
<h2 id="browsers">Web browsers</h2>
<div class="impl">
<p>This section describes features that apply most directly to Web
browsers. Having said that, except where specified otherwise, the
requirements defined in this section <em>do</em> apply to all user
agents, whether they are Web browsers or not.</p>
</div>
<h3 id="windows">Browsing contexts</h3>
<p>A <dfn>browsing context</dfn> is an environment in which
<code>Document</code> objects are presented to the user.</p>
<p class="note">A tab or window in a Web browser typically contains
a <span>browsing context</span>, as does an <code>iframe</code><span
class="impl"> or <code>frame</code>s in a
<code>frameset</code></span>.</p>
<p>Each <span>browsing context</span> has a corresponding
<code>WindowProxy</code> object.</p>
<p>A <span>browsing context</span> has a <span>session
history</span>, which lists the <code>Document</code> objects that
that <span>browsing context</span> has presented, is presenting, or
will present. At any time, one <code>Document</code> in each
<span>browsing context</span> is designated the <dfn>active
document</dfn>.</p>
<p>Each <code>Document</code> has a collection of one or more <span
title="view">views</span>.</p>
<p>A <dfn>view</dfn> is a user agent interface tied to a particular
media used for the presentation of a particular
<code>Document</code> object in some media. A view may be
interactive. Each view is represented by an
<code>AbstractView</code> object. <a
href="#refsDOMVIEWS">[DOMVIEWS]</a></p>
<p>The main <span>view</span> through which a user primarily
interacts with a user agent is the <dfn>default view</dfn>. The
<code>AbstractView</code> object that represents this view <span
class="impl">must also implement the <code>Window</code> interface,
and</span> is referred to as the <code>Document</code>'s
<code>Window</code> object. <code>WindowProxy</code> objects forward
everything to the <span>active document</span>'s <span>default
view</span>'s <code>Window</code> object.</p>
<div class="impl">
<p>The <code title="dom-document-defaultView">defaultView</code>
attribute on the <code>Document</code> object's
<code>DocumentView</code> interface must return the <span>browsing
context</span>'s <code>WindowProxy</code> object, not the actual
<code>AbstractView</code> object of the <span>default
view</span>. <a href="#refsDOMVIEWS">[DOMVIEWS]</a></p>
</div>
<p class="note">The <code title="dom-document">document</code>
attribute of an <code>AbstractView</code> object representing a
<span>view</span> gives the view's corresponding
<code>Document</code> object. <a
href="#refsDOMVIEWS">[DOMVIEWS]</a></p>
<p class="note">In general, there is a 1-to-1 mapping from the
<code>Window</code> object to the <code>Document</code> object. In
one particular case, a set of <span title="view">views</span> can be
reused for the presentation of a second <code>Document</code> in the
same <span>browsing context</span>, such that the mapping is then
2:1. This occurs when a <span>browsing context</span> is <span
title="navigate">navigated</span> from the initial
<code>about:blank</code> <code>Document</code> to another, with
<span>replacement enabled</span>.</p>
<div class="impl">
<p>Events that use the <code>UIEvent</code> interface are related to
a specific <span>view</span> (the view in which the event happened);
when that <span>view</span> is the <span>default view</span>, the
event object's <code title="">view</code> attribute's must return
the <code>WindowProxy</code> object of the <span>browsing
context</span> of that <span>view</span>, not the actual
<code>AbstractView</code> object of the <span>default
view</span>. <a href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
</div>
<p class="note">A typical Web browser has one obvious
<span>view</span> per <code>Document</code>: the browser's window
(screen media). This is typically the <span>default view</span>. If
a page is printed, however, a second view becomes evident, that of
the print media. The two views always share the same underlying
<code>Document</code> object, but they have a different presentation
of that object. A speech browser might have a different
<span>default view</span>, using the speech media.</p>
<p class="note">A <code>Document</code> does not necessarily have a
<span>browsing context</span> associated with it. In particular,
data mining tools are likely to never instantiate browsing
contexts.</p>
<hr>
<p>A <span>browsing context</span> can have a <dfn>creator browsing
context</dfn>, the <span>browsing context</span> that was
responsible for its creation. <span class="impl">Except when
otherwise specified, a <span>browsing context</span> has no
<span>creator browsing context</span>.</span></p>
<p>If a <span>browsing context</span> <var title="">A</var> has a
<span>creator browsing context</span>, then the
<code>Document</code> that was the <span>active document</span> of
that <span>creator browsing context</span> at the time <var
title="">A</var> was created is the <dfn>creator
<code>Document</code></dfn>.</p>
<div class="impl">
<p>When a <span>browsing context</span> is first created, it must be
created with a single <code>Document</code> in its session history,
whose <span title="the document's address">address</span> is
<code>about:blank</code>, which is marked as being an <span
title="HTML documents">HTML document</span>, and whose <span
title="document's character encoding">character encoding</span> is
UTF-8. The <code>Document</code> must have a single child
<code>html</code> node, which itself has a single child
<code>body</code> node.</p>
<p class="note">If the <span>browsing context</span> is created
specifically to be immediately navigated, then that initial
navigation will have <span>replacement enabled</span>.</p>
<p id="about-blank-origin">The <span>origin</span> of the
<code>about:blank</code> <code>Document</code> is set when the
<code>Document</code> is created. If the new <span>browsing
context</span> has a <span>creator browsing context</span>, then the
<span>origin</span> of the <code>about:blank</code>
<code>Document</code> is the <span>origin</span> of the
<span>creator <code>Document</code></span>. Otherwise, the
<span>origin</span> of the <code>about:blank</code>
<code>Document</code> is a globally unique identifier assigned when
the new <span>browsing context</span> is created.</p>
</div>
<h4>Nested browsing contexts</h4>
<p>Certain elements (for example, <code>iframe</code> elements) can
instantiate further <span title="browsing context">browsing
contexts</span>. These are called <dfn title="nested browsing
context">nested browsing contexts</dfn>. If a browsing context <var
title="">P</var> has an element <var title="">E</var> in one of its
<code>Document</code>s <var title="">D</var> that nests another
browsing context <var title="">C</var> inside it, then <var
title="">P</var> is said to be the <dfn>parent browsing
context</dfn> of <var title="">C</var>, <var title="">C</var> is
said to be a <dfn>child browsing context</dfn> of <var
title="">P</var>, <var title="">C</var> is said to be <dfn
title="browsing context nested through">nested through</dfn> <var
title="">D</var>, and <var title="">E</var> is said to be the
<dfn>browsing context container</dfn> of <var title="">C</var>.</p>
<p>A browsing context <var title="">A</var> is said to be an
ancestor of a browsing context <var title="">B</var> if there exists
a browsing context <var title="">A'</var> that is a <span>child
browsing context</span> of <var title="">A</var> and that is itself
an ancestor of <var title="">B</var>, or if there is a browsing
context <var title="">P</var> that is a <span>child browsing
context</span> of <var title="">A</var> and that is the <span>parent
browsing context</span> of <var title="">B</var>.</p>
<p>The browsing context with no <span>parent browsing context</span>
is the <dfn>top-level browsing context</dfn> of all the browsing
contexts <span title="nested browsing context">nested</span> within
it (either directly or indirectly through other nested browsing
contexts).</p>
<p>The transitive closure of <span title="parent browsing
context">parent browsing contexts</span> for a <span>nested browsing
context</span> gives the list of <dfn title="ancestor browsing
context">ancestor browsing contexts</dfn>.</p>
<p>A <code>Document</code> is said to be <dfn>fully active</dfn>
when it is the <span>active document</span> of its <span>browsing
context</span>, and either its browsing context is a <span>top-level
browsing context</span>, or the <code>Document</code> <span
title="browsing context nested through">through which</span> that
browsing context is <span title="nested browsing
context">nested</span> is itself <span>fully active</span>.</p>
<p>Because they are nested through an element, <span title="child
browsing context">child browsing contexts</span> are always tied to
a specific <code>Document</code> in their <span>parent browsing
context</span>. User agents must not allow the user to interact with
<span title="child browsing context">child browsing contexts</span>
of elements that are in <code>Document</code>s that are not
themselves <span>fully active</span>.</p>
<p>A <span>nested browsing context</span> can have a <span>seamless
browsing context flag</span> set, if it is embedded through an
<code>iframe</code> element with a <code
title="attr-iframe-seamless">seamless</code> attribute.</p>
<h5>Navigating nested browsing contexts in the DOM</h5>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-top">top</code></dt>
<dd>
<p>Returns the <code>WindowProxy</code> for the <span>top-level browsing context</span>.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-parent">parent</code></dt>
<dd>
<p>Returns the <code>WindowProxy</code> for the <span>parent browsing context</span>.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-frameElement">frameElement</code></dt>
<dd>
<p>Returns the <code>Element</code> for the <span>browsing context container</span>.</p>
<p>Returns null if there isn't one.</p>
<p>Throws a <code>SECURITY_ERR</code> exception in cross-origin situations.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-top"><code>top</code></dfn> IDL attribute on
the <code>Window</code> object of a <code>Document</code> in a
<span>browsing context</span> <var title="">b</var> must return the
<code>WindowProxy</code> object of its <span>top-level browsing
context</span> (which would be its own <code>WindowProxy</code>
object if it was a <span>top-level browsing context</span>
itself).</p>
<p>The <dfn title="dom-parent"><code>parent</code></dfn> IDL
attribute on the <code>Window</code> object of a
<code>Document</code> in a <span>browsing context</span> <var
title="">b</var> must return the <code>WindowProxy</code> object of
the <span>parent browsing context</span>, if there is one (i.e. if
<var title="">b</var> is a <span>child browsing context</span>), or
the <code>WindowProxy</code> object of the <span>browsing
context</span> <var title="">b</var> itself, otherwise (i.e. if it
is a <span>top-level browsing context</span>).</p>
<p>The <dfn title="dom-frameElement"><code>frameElement</code></dfn>
IDL attribute on the <code>Window</code> object of a
<code>Document</code> <var title="">d</var>, on getting, must run
the following algorithm:</p>
<ol>
<li><p>If <var title="">d</var> is not a <code>Document</code> in a
<span>child browsing context</span>, return null and abort these
steps.</p></li>
<li><p>If the <span>parent browsing context</span>'s <span>active
document</span> does not have the <span title="same
origin">same</span> <span>effective script origin</span> as the
<span>first script</span>, then throw a <code>SECURITY_ERR</code>
exception.</p></li>
<li><p>Otherwise, return the <span>browsing context
container</span> for <var title="">b</var>.</p></li>
</ol>
</div>
<h4>Auxiliary browsing contexts</h4>
<p>It is possible to create new browsing contexts that are related
to a <span>top-level browsing context</span> without being nested
through an element. Such browsing contexts are called <dfn
title="auxiliary browsing context">auxiliary browsing
contexts</dfn>. Auxiliary browsing contexts are always <span
title="top-level browsing context">top-level browsing
contexts</span>.</p>
<p>An <span>auxiliary browsing context</span> has an <dfn>opener
browsing context</dfn>, which is the <span>browsing context</span>
from which the <span>auxiliary browsing context</span> was created,
and it has a <dfn>furthest ancestor browsing context</dfn>, which is
the <span>top-level browsing context</span> of the <span>opener
browsing context</span> when the <span>auxiliary browsing
context</span> was created.</p>
<h5>Navigating auxiliary browsing contexts in the DOM</h5>
<p>The <dfn title="dom-opener"><code>opener</code></dfn> IDL
attribute on the <code>Window</code> object must return the
<code>WindowProxy</code> object of the <span>browsing context</span>
from which the current <span>browsing context</span> was created
(its <span>opener browsing context</span>), if there is one and it
is still available.</p>
<h4>Secondary browsing contexts</h4>
<p>User agents may support <dfn title="secondary browsing
context">secondary browsing contexts</dfn>, which are <span
title="browsing context">browsing contexts</span> that form part of
the user agent's interface, apart from the main content area.</p>
<div class="impl">
<h4>Security</h4>
<p>A <span>browsing context</span> <var title="">A</var> is
<dfn>allowed to navigate</dfn> a second <span>browsing
context</span> <var title="">B</var> if one of the following
conditions is true:</p>
<ul>
<li>Either the <span>origin</span> of the <span>active
document</span> of <var title="">A</var> is the <span title="same
origin">same</span> as the <span>origin</span> of the <span>active
document</span> of <var title="">B</var>, or</li>
<li>The browsing context <var title="">A</var> is a <span>nested
browsing context</span> and its <span>top-level browsing
context</span> is <var title="">B</var>, or</li>
<li>The browsing context <var title="">B</var> is an
<span>auxiliary browsing context</span> and <var title="">A</var>
is <span>allowed to navigate</span> <var title="">B</var>'s
<span>opener browsing context</span>, or</li>
<li>The browsing context <var title="">B</var> is not a
<span>top-level browsing context</span>, but there exists an
<span>ancestor browsing context</span> of <var title="">B</var>
whose <span>active document</span> has the <span title="same
origin">same</span> <span>origin</span> as the <span>active
document</span> of <var title="">A</var> (possibly in fact being
<var title="">A</var> itself).</li>
</ul>
<hr>
<p>An element has a <dfn>browsing context scope origin</dfn> if its
<code>Document</code>'s <span>browsing context</span> is a
<span>top-level browsing context</span> or if all of its
<code>Document</code>'s <span title="ancestor browsing
context">ancestor browsing contexts</span> all have <span
title="active document">active documents</span> whose
<span>origin</span> are the <span>same origin</span> as the
element's <code>Document</code>'s <span>origin</span>. If an element
has a <span>browsing context scope origin</span>, then its value is
the <span>origin</span> of the element's <code>Document</code>.</p>
</div>
<div class="impl">
<h4>Groupings of browsing contexts</h4>
<p>Each <span>browsing context</span> is defined as having a list of
zero or more <dfn>directly reachable browsing contexts</dfn>. These
are:</p>
<ul>
<li>All the <span>browsing context</span>'s <span title="child
browsing context">child browsing contexts</span>.</li>
<li>The <span>browsing context</span>'s <span>parent browsing
context</span>.</li>
<li>All the <span title="browsing context">browsing contexts</span>
that have the <span>browsing context</span> as their <span>opener
browsing context</span>.</li>
<li>The <span>browsing context</span>'s <span>opener browsing
context</span>.</li>
</ul>
<p>The transitive closure of all the <span title="browsing
context">browsing contexts</span> that are <span>directly reachable
browsing contexts</span> forms a <dfn>unit of related browsing
contexts</dfn>.</p>
<p>Each <span>unit of related browsing contexts</span> is then
further divided into the smallest number of groups such that every
member of each group has an <span>effective script origin</span>
that, through appropriate manipulation of the <code
title="dom-document-domain">document.domain</code> attribute, could
be made to be the same as other members of the group, but could not
be made the same as members of any other group. Each such group is a
<dfn>unit of related similar-origin browsing contexts</dfn>.</p>
<p>Each <span>unit of related similar-origin browsing
contexts</span> can have a <dfn>first script</dfn> which is used to
obtain, amongst other things, the <span>script's base URL</span> to
<span title="resolve a url">resolve</span> relative <span
title="URL">URLs</span> used in scripts running in that <span>unit
of related similar-origin browsing contexts</span>. Initially, there
is no <span>first script</span>.</p>
<p class="note">There is at most one <span>event loop</span> per
<span>unit of related similar-origin browsing contexts</span>.</p>
</div>
<h4>Browsing context names</h4>
<p>Browsing contexts can have a <dfn>browsing context name</dfn>. By
default, a browsing context has no name (its name is not set).</p>
<p>A <dfn>valid browsing context name</dfn> is any string with at
least one character that does not start with a U+005F LOW LINE
character. (Names starting with an underscore are reserved for
special keywords.)</p>
<p>A <dfn>valid browsing context name or keyword</dfn> is any string
that is either a <span>valid browsing context name</span> or that is
an <span>ASCII case-insensitive</span> match for one of: <code
title="">_blank</code>, <code title="">_self</code>, <code
title="">_parent</code>, or <code title="">_top</code>.</p>
<div class="impl">
<p><dfn>The rules for choosing a browsing context given a browsing
context name</dfn> are as follows. The rules assume that they are
being applied in the context of a <span>browsing context</span>.</p>
<ol>
<li><p>If the given browsing context name is the empty string or
<code title="">_self</code>, then the chosen browsing context must
be the current one.</p></li>
<li><p>If the given browsing context name is <code
title="">_parent</code>, then the chosen browsing context must be
the <span><em>parent</em> browsing context</span> of the current
one, unless there isn't one, in which case the chosen browsing
context must be the current browsing context.</p></li>
<li><p>If the given browsing context name is <code
title="">_top</code>, then the chosen browsing context must be the
most <span>top-level browsing context</span> of the current
one.</p></li>
<li>
<p>If the given browsing context name is not <code
title="">_blank</code> and there exists a browsing context whose
<span title="browsing context name">name</span> is the same as the
given browsing context name, and the current browsing context is
<span>allowed to navigate</span> that browsing context, and the
user agent determines that the two browsing contexts are related
enough that it is ok if they reach each other, then that browsing
context must be the chosen one. If there are multiple matching
browsing contexts, the user agent should select one in some
arbitrary consistent manner, such as the most recently opened,
most recently focused, or more closely related.</p>
</li>
<li>
<p>Otherwise, a new browsing context is being requested, and what
happens depends on the user agent's configuration and/or
abilities:</p>
<dl>
<dt id="sandboxWindowOpen">If the current browsing context has
the <span>sandboxed navigation browsing context flag</span>
set.</dt>
<dd><p>The user agent may offer to create a new <span>top-level
browsing context</span> or reuse an existing <span>top-level
browsing context</span>. If the user picks one of those options,
then the designated browsing context must be the chosen one (the
browsing context's name isn't set to the given browsing context
name). Otherwise (if the user agent doesn't offer the option to
the user, or if the user declines to allow a browsing context to
be used) there must not be a chosen browsing context.</p></dd>
<dt id="noopener">If the user agent has been configured such that
in this instance it will create a new browsing context, and the
browsing context is being requested as part of <span
title="following hyperlinks">following a hyperlink</span> whose
<a href="#linkTypes">link types</a> include the <code
title="rel-noreferrer">noreferrer</code> keyword</dt>
<dd><p>A new <span>top-level browsing context</span> must be
created. If the given browsing context name is not <code
title="">_blank</code>, then the new top-level browsing context's
name must be the given browsing context name (otherwise, it has
no name). The chosen browsing context must be this new browsing
context.</p>
<p class="note">If it is immediately <span
title="navigate">navigated</span>, then the navigation will be
done with <span>replacement enabled</span>.</p></dd>
<dt>If the user agent has been configured such that in this
instance it will create a new browsing context, and the <code
title="rel-noreferrer">noreferrer</code> keyword doesn't
apply</dt>
<dd><p>A new <span>auxiliary browsing context</span> must be
created, with the <span>opener browsing context</span> being the
current one. If the given browsing context name is not <code
title="">_blank</code>, then the new auxiliary browsing context's
name must be the given browsing context name (otherwise, it has
no name). The chosen browsing context must be this new browsing
context.</p>
<p>If it is immediately <span title="navigate">navigated</span>,
then the navigation will be done with <span>replacement
enabled</span>.</p></dd>
<dt>If the user agent has been configured such that in this
instance it will reuse the current browsing context</dt>
<dd><p>The chosen browsing context is the current browsing
context.</p></dd>
<dt>If the user agent has been configured such that in this
instance it will not find a browsing context</dt>
<dd><p>There must not be a chosen browsing context.</p></dd>
</dl>
<p>User agent implementors are encouraged to provide a way for
users to configure the user agent to always reuse the current
browsing context.</p>
</li>
</ol>
</div>
<div class="impl">
<h3>The <code>WindowProxy</code> object</h3>
<p>As mentioned earlier, each <span>browsing context</span> has a
<dfn><code>WindowProxy</code></dfn> object. This object is unusual
in that all operations that would be performed on it must be
performed on the <code>Window</code> object of the <span>browsing
context</span>'s <span>active document</span> instead. It is thus
indistinguishable from that <code>Window</code> object in every way
until the <span>browsing context</span> is navigated.</p>
<p>There is no <code>WindowProxy</code> interface object.</p>
<p class="note">The <code>WindowProxy</code> object allows scripts
to act as if each <span>browsing context</span> had a single
<code>Window</code> object, while still keeping separate
<code>Window</code> objects for each <code>Document</code>.</p>
<div class="example">
<p>In the following example, the variable <var title="">x</var> is
set to the <code>WindowProxy</code> object returned by the <code
title="dom-window">window</code> accessor on the global object. All
of the expressions following the assignment return true, because in
every respect, the <code>WindowProxy</code> object acts like the
underlying <code>Window</code> object.</p>
<pre>var x = window;
x instanceof Window; // true
x === this; // true</pre>
</div>
</div>
<h3>The <code>Window</code> object</h3>
<pre class="idl">[OverrideBuiltins]
interface <dfn>Window</dfn> {
// the current browsing context
readonly attribute <span>WindowProxy</span> <span title="dom-window">window</span>;
readonly attribute <span>WindowProxy</span> <span title="dom-self">self</span>;
attribute DOMString <span title="dom-name">name</span>;
[PutForwards=href] readonly attribute <span>Location</span> <span title="dom-location">location</span>;
readonly attribute <span>History</span> <span title="dom-history">history</span>;
readonly attribute <span>UndoManager</span> <span title="dom-undoManager">undoManager</span>;
<span>Selection</span> <span title="dom-getSelection">getSelection</span>();
[Replaceable] readonly attribute <span>BarProp</span> <span title="dom-window-locationbar">locationbar</span>;
[Replaceable] readonly attribute <span>BarProp</span> <span title="dom-window-menubar">menubar</span>;
[Replaceable] readonly attribute <span>BarProp</span> <span title="dom-window-personalbar">personalbar</span>;
[Replaceable] readonly attribute <span>BarProp</span> <span title="dom-window-scrollbars">scrollbars</span>;
[Replaceable] readonly attribute <span>BarProp</span> <span title="dom-window-statusbar">statusbar</span>;
[Replaceable] readonly attribute <span>BarProp</span> <span title="dom-window-toolbar">toolbar</span>;<!--
[Replaceable] readonly attribute <span>BarProp</span> <span title="dom-window-directories">directories</span>; // legacy (Gecko-only) -->
void <span title="dom-window-close">close</span>();
void <span title="dom-window-focus">focus</span>();
void <span title="dom-window-blur">blur</span>();
// other browsing contexts
[Replaceable] readonly attribute <span>WindowProxy</span> <span title="dom-frames">frames</span>;
[Replaceable] readonly attribute unsigned long <span title="dom-length">length</span>;
readonly attribute <span>WindowProxy</span> <span title="dom-top">top</span>;
[Replaceable] readonly attribute <span>WindowProxy</span> <span title="dom-opener">opener</span>;
readonly attribute <span>WindowProxy</span> <span title="dom-parent">parent</span>;
readonly attribute <span>Element</span> <span title="dom-frameElement">frameElement</span>;
<span>WindowProxy</span> <span title="dom-open">open</span>(in optional DOMString url, in optional DOMString target, in optional DOMString features, in optional DOMString replace);
<span title="dom-window-item">getter</span> <span>WindowProxy</span> (in unsigned long index);
<span title="dom-window-namedItem">getter</span> <span>WindowProxy</span> (in DOMString name);
// the user agent
readonly attribute <span>Navigator</span> <span title="dom-navigator">navigator</span>; <!-- IE also has window.clientInformation === window.navigator -->
readonly attribute <span>ApplicationCache</span> <span title="dom-applicationCache">applicationCache</span>;
// user prompts
void <span title="dom-alert">alert</span>(in DOMString message);
boolean <span title="dom-confirm">confirm</span>(in DOMString message);
DOMString <span title="dom-prompt">prompt</span>(in DOMString message, in optional DOMString default);
void <span title="dom-print">print</span>();
any <span title="dom-showModalDialog">showModalDialog</span>(in DOMString url, in optional any argument<!--, in optional DOMString features-->);
// <span>cross-document messaging</span>
void <span title="dom-window-postMessage-2">postMessage</span>(in any message, in DOMString targetOrigin);
void <span title="dom-window-postMessage-3">postMessage</span>(in any message, in <span>MessagePortArray</span> ports, in DOMString targetOrigin);
// <span>event handler IDL attributes</span>
attribute <span>Function</span> <span title="handler-onabort">onabort</span>;
attribute <span>Function</span> <span title="handler-window-onafterprint">onafterprint</span>;
attribute <span>Function</span> <span title="handler-window-onbeforeprint">onbeforeprint</span>;
attribute <span>Function</span> <span title="handler-window-onbeforeunload">onbeforeunload</span>;
attribute <span>Function</span> <span title="handler-window-onblur">onblur</span>;
attribute <span>Function</span> <span title="handler-oncanplay">oncanplay</span>;
attribute <span>Function</span> <span title="handler-oncanplaythrough">oncanplaythrough</span>;
attribute <span>Function</span> <span title="handler-onchange">onchange</span>;
attribute <span>Function</span> <span title="handler-onclick">onclick</span>;
attribute <span>Function</span> <span title="handler-oncontextmenu">oncontextmenu</span>;
attribute <span>Function</span> <span title="handler-ondblclick">ondblclick</span>;
attribute <span>Function</span> <span title="handler-ondrag">ondrag</span>;
attribute <span>Function</span> <span title="handler-ondragend">ondragend</span>;
attribute <span>Function</span> <span title="handler-ondragenter">ondragenter</span>;
attribute <span>Function</span> <span title="handler-ondragleave">ondragleave</span>;
attribute <span>Function</span> <span title="handler-ondragover">ondragover</span>;
attribute <span>Function</span> <span title="handler-ondragstart">ondragstart</span>;
attribute <span>Function</span> <span title="handler-ondrop">ondrop</span>;
attribute <span>Function</span> <span title="handler-ondurationchange">ondurationchange</span>;
attribute <span>Function</span> <span title="handler-onemptied">onemptied</span>;
attribute <span>Function</span> <span title="handler-onended">onended</span>;
attribute <span>Function</span> <span title="handler-window-onerror">onerror</span>;
attribute <span>Function</span> <span title="handler-window-onfocus">onfocus</span>;
attribute <span>Function</span> <span title="handler-onformchange">onformchange</span>;
attribute <span>Function</span> <span title="handler-onforminput">onforminput</span>;
attribute <span>Function</span> <span title="handler-window-onhashchange">onhashchange</span>;
attribute <span>Function</span> <span title="handler-oninput">oninput</span>;
attribute <span>Function</span> <span title="handler-oninvalid">oninvalid</span>;
attribute <span>Function</span> <span title="handler-onkeydown">onkeydown</span>;
attribute <span>Function</span> <span title="handler-onkeypress">onkeypress</span>;
attribute <span>Function</span> <span title="handler-onkeyup">onkeyup</span>;
attribute <span>Function</span> <span title="handler-window-onload">onload</span>;
attribute <span>Function</span> <span title="handler-onloadeddata">onloadeddata</span>;
attribute <span>Function</span> <span title="handler-onloadedmetadata">onloadedmetadata</span>;
attribute <span>Function</span> <span title="handler-onloadstart">onloadstart</span>;
attribute <span>Function</span> <span title="handler-window-onmessage">onmessage</span>;
attribute <span>Function</span> <span title="handler-onmousedown">onmousedown</span>;
attribute <span>Function</span> <span title="handler-onmousemove">onmousemove</span>;
attribute <span>Function</span> <span title="handler-onmouseout">onmouseout</span>;
attribute <span>Function</span> <span title="handler-onmouseover">onmouseover</span>;
attribute <span>Function</span> <span title="handler-onmouseup">onmouseup</span>;
attribute <span>Function</span> <span title="handler-onmousewheel">onmousewheel</span>;
attribute <span>Function</span> <span title="handler-window-onoffline">onoffline</span>;
attribute <span>Function</span> <span title="handler-window-ononline">ononline</span>;
attribute <span>Function</span> <span title="handler-onpause">onpause</span>;
attribute <span>Function</span> <span title="handler-onplay">onplay</span>;
attribute <span>Function</span> <span title="handler-onplaying">onplaying</span>;
attribute <span>Function</span> <span title="handler-window-onpagehide">onpagehide</span>;
attribute <span>Function</span> <span title="handler-window-onpageshow">onpageshow</span>;
attribute <span>Function</span> <span title="handler-window-onpopstate">onpopstate</span>;
attribute <span>Function</span> <span title="handler-onprogress">onprogress</span>;
attribute <span>Function</span> <span title="handler-onratechange">onratechange</span>;
attribute <span>Function</span> <span title="handler-onreadystatechange">onreadystatechange</span>;
attribute <span>Function</span> <span title="handler-window-onredo">onredo</span>;
attribute <span>Function</span> <span title="handler-window-onresize">onresize</span>;
attribute <span>Function</span> <span title="handler-onscroll">onscroll</span>;
attribute <span>Function</span> <span title="handler-onseeked">onseeked</span>;
attribute <span>Function</span> <span title="handler-onseeking">onseeking</span>;
attribute <span>Function</span> <span title="handler-onselect">onselect</span>;
attribute <span>Function</span> <span title="handler-onshow">onshow</span>;
attribute <span>Function</span> <span title="handler-onstalled">onstalled</span>;
attribute <span>Function</span> <span title="handler-window-onstorage">onstorage</span>;
attribute <span>Function</span> <span title="handler-onsubmit">onsubmit</span>;
attribute <span>Function</span> <span title="handler-onsuspend">onsuspend</span>;
attribute <span>Function</span> <span title="handler-ontimeupdate">ontimeupdate</span>;
attribute <span>Function</span> <span title="handler-window-onundo">onundo</span>;
attribute <span>Function</span> <span title="handler-window-onunload">onunload</span>;
attribute <span>Function</span> <span title="handler-onvolumechange">onvolumechange</span>;
attribute <span>Function</span> <span title="handler-onwaiting">onwaiting</span>;
};
<span>Window</span> implements <span>EventTarget</span>;</pre>
<!-- for more features to add here, look here:
http://msdn.microsoft.com/workshop/author/dhtml/reference/objects/obj_window.asp
http://www.mozilla.org/docs/dom/domref/dom_window_ref.html
http://lxr.mozilla.org/mozilla/source/dom/public/idl/base/nsIDOMWindow.idl - scrollBy, etc
http://lxr.mozilla.org/mozilla/source/dom/public/idl/base/nsIDOMWindowInternal.idl - DOM level 0
-->
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-window">window</code></dt>
<dt><var title="">window</var> . <code title="dom-frames">frames</code></dt>
<dt><var title="">window</var> . <code title="dom-self">self</code></dt>
<dd>
<p>These attributes all return <var title="">window</var>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-window"><code>window</code></dfn>, <dfn
title="dom-frames"><code>frames</code></dfn>, and <dfn
title="dom-self"><code>self</code></dfn> IDL attributes must all
return the <code>Window</code> object's <span>browsing
context</span>'s <code>WindowProxy</code> object.</p>
</div>
<div class="impl">
<h4>Security</h4>
<p>User agents must raise a <code>SECURITY_ERR</code> exception
whenever any of the members of a <code>Window</code> object are
accessed by scripts whose <span>effective script origin</span> is
not the same as the <code>Window</code> object's
<code>Document</code>'s <span>effective script origin</span>, with
the following exceptions:</p>
<ul>
<li>The <code title="dom-location">location</code> object
<li>The <code title="dom-window-postMessage-2">postMessage()</code>
method with two arguments
<li>The <code title="dom-window-postMessage-3">postMessage()</code>
method with three arguments
<li>The <code title="dom-frames">frames</code> attribute
<li>The <span>dynamic nested browsing context properties</span>
</ul>
<p>When a script whose <span>effective script origin</span> is not
the same as the <code>Window</code> object's <code>Document</code>'s
<span>effective script origin</span> attempts to access that
<code>Window</code> object's methods or attributes, the user agent
must act as if any changes to the <code>Window</code> object's
properties, getters, setters, etc, were not present.</p>
<p>For members that return objects (including function objects),
each distinct <span>effective script origin</span> that is not the
same as the <code>Window</code> object's <code>Document</code>'s
<span>effective script origin</span> must be provided with a
separate set of objects. These objects must have the prototype chain
appropriate for the script for which the objects are created (not
those that would be appropriate for scripts whose <span>script's
global object</span> is the <code>Window</code> object in
question).</p>
<div class="example">
<p>For instance, if two frames containing <code>Document</code>s
from different <span title="origin">origins</span> access the same
<code>Window</code> object's <code
title="dom-window-postMessage-2">postMessage()</code> method, they
will get distinct objects that are not equal.</p>
</div>
</div>
<h4>APIs for creating and navigating browsing contexts by name</h4>
<dl class="domintro">
<dt><var title="">window</var> = <var title="">window</var> . <code title="dom-open">open</code>( [ <var title="">url</var> [, <var title="">target</var> [, <var title="">features</var> [, <var title="">replace</var> ] ] ] ] )</dt>
<dd>
<p>Opens a window to show <var title="">url</var> (defaults to
<code>about:blank</code>), and returns it. The <var
title="">target</var> argument gives the name of the new
window. If a window exists with that name already, it is
reused. The <var title="">replace</var> attribute, if true, means
that whatever page is currently open in that window will be
removed from the window's session history. The <var
title="">features</var> argument is ignored.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-name">name</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the name of the window.</p>
<p>Can be set, to change the name.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-close">close</code>()</dt>
<dd>
<p>Closes the window.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-open"><code>open()</code></dfn> method on
<code>Window</code> objects provides a mechanism for <span
title="navigate">navigating</span> an existing <span>browsing
context</span> or opening and navigating an <span>auxiliary browsing
context</span>.</p>
<p>The method has four arguments, though they are all optional.</p>
<p>The first argument, <var title="">url</var>, must be a
<span>valid URL</span> for a page to load in the browsing
context. If no arguments are provided, or if the first argument is
the empty string, then the <var title="">url</var> argument defaults
to "<code>about:blank</code>". The argument must be <span
title="resolve a url">resolved</span> to an <span>absolute
URL</span> (or an error), relative to the <span>first
script</span>'s <span title="script's base URL">base URL</span>,
when the method is invoked.</p>
<p>The second argument, <var title="">target</var>, specifies the
<span title="browsing context name">name</span> of the browsing
context that is to be navigated. It must be a <span>valid browsing
context name or keyword</span>. If fewer than two arguments are
provided, then the <var title="">name</var> argument defaults to the
value "<code>_blank</code>".</p>
<p>The third argument, <var title="">features</var>, has no effect
and is supported for historical reasons only.</p>
<p>The fourth argument, <var title="">replace</var>, specifies
whether or not the new page will <span title="replacement
enabled">replace</span> the page currently loaded in the browsing
context, when <var title="">target</var> identifies an existing
browsing context (as opposed to leaving the current page in the
browsing context's <span>session history</span>). When three or
fewer arguments are provided, <var title="">replace</var> defaults
to false.</p>
<p>When the method is invoked, the user agent must first select a
<span>browsing context</span> to navigate by applying <span>the
rules for choosing a browsing context given a browsing context
name</span> using the <var title="">target</var> argument as the
name and the <span>browsing context</span> of the script as the
context in which the algorithm is executed, unless the user has
indicated a preference, in which case the browsing context to
navigate may instead be the one indicated by the user.</p>
<p class="example">For example, suppose there is a user agent that
supports control-clicking a link to open it in a new tab. If a user
clicks in that user agent on an element whose <code
title="handler-onclick">onclick</code> handler uses the <code
title="dom-open">window.open()</code> API to open a page in an
iframe, but, while doing so, holds the control key down, the user
agent could override the selection of the target browsing context to
instead target a new tab.</p>
<p>Then, the user agent must <span>navigate</span> the selected
<span>browsing context</span> to the <span>absolute URL</span> (or
error) obtained from <span title="resolve a url">resolving</span>
<var title="">url</var> earlier. If the <var title="">replace</var>
is true, then <span title="replacement enabled">replacement must be
enabled</span>; otherwise, it must not be enabled unless the
<span>browsing context</span> was just created as part of
<span>the rules for choosing a browsing context given a browsing
context name</span>. The navigation must be done with the <span
title="script's browsing context">browsing context</span> of the
<span>first script</span> as the <span>source browsing
context</span>.</p>
<p>The method must return the <code>WindowProxy</code> object of the
<span>browsing context</span> that was navigated, or null if no
browsing context was navigated.</p>
<hr>
<p>The <dfn title="dom-name"><code>name</code></dfn> attribute of
the <code>Window</code> object must, on getting, return the current
name of the <span>browsing context</span>, and, on setting, set the
name of the <span>browsing context</span> to the new value.</p>
<p class="note">The name <a href="#resetBCName">gets reset</a> when
the browsing context is navigated to another domain.</p>
<hr>
<p>The <dfn title="dom-window-close"><code>close()</code></dfn>
method on <code>Window</code> objects should, if the corresponding
<span>browsing context</span> <var title="">A</var> is an
<span>auxiliary browsing context</span> that was created by a script
(as opposed to by an action of the user), and if the <span
title="script's browsing context">browsing context</span> of the
<span title="concept-script">script</span> that invokes the method
is <span>allowed to navigate</span> the <span>browsing
context</span> <var title="">A</var>, close the <span>browsing
context</span> <var title="">A</var> (and may <span title="a
browsing context is discarded">discard</span> it too).</p>
</div>
<h4>Accessing other browsing contexts</h4>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-length">length</code></dt>
<dd>
<p>Returns the number of <span title="child browsing
context">child browsing contexts</span>.</p>
</dd>
<dt><var title="">window</var>[<var title="">index</var>]</dt>
<dd>
<p>Returns the indicated <span>child browsing context</span>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-length"><code>length</code></dfn> IDL
attribute on the <code>Window</code> interface must return the
number of <span title="child browsing context">child browsing
contexts</span> of the <span>active document</span> of that
<code>Window</code> object, if that <code>Window</code>'s
<span>browsing context</span> shares the same <span>event
loop</span> as the <span>script's browsing context</span> of the
<span>first script</span> accessing the IDL attribute; otherwise, it
must return zero.</p>
<!-- in other words, frames are only accessible to same-thread processes -->
<p>The <span>indices of the supported indexed properties</span> on
the <code>Window</code> object at any instant are the numbers in the
range 0 .. <span title=""><var title="">n</var>-1</span>, where <var
title="">n</var> is the number returned by the <code
title="dom-length">length</code> IDL attribute. If <var
title="">n</var> is zero then there are no <span>supported indexed
properties</span>.</p>
<p>When a <code>Window</code> object is <dfn
title="dom-window-item">indexed to retrieve an indexed
property</dfn> <var title="">index</var>, the value returned must be
the <var title="">index</var>th <span>child browsing context</span>
of the <code>Document</code>, sorted in the <span>tree order</span>
of the elements nesting those <span title="browsing
context">browsing contexts</span>.</p>
<p>These properties are the <dfn>dynamic nested browsing context
properties</dfn>.</p>
</div>
<h4>Named access on the <code>Window</code> object</h4>
<dl class="domintro">
<dt><var title="">window</var>[<var title="">name</var>]</dt>
<dd>
<p>Returns the indicated <span>child browsing context</span>.</p>
</dd>
</dl>
<div class="impl">
<p>The <code>Window</code> interface <span title="support named
properties">supports named properties</span>. The <span>names of the
supported named properties</span> at any moment consist of:</p>
<ul>
<li>The value of the <code title="">name</code> content attribute
for all <code>a</code>, <code>applet</code>, <code>area</code>,
<code>embed</code>, <code>frame</code>, <code>frameset</code>,
<code>form</code>, <code>iframe</code>, <code>img</code>, and
<code>object</code> elements in the <span>active document</span>
that have a <code title="">name</code> content attribute, and,</li>
<li>The value of the <code title="attr-id">id</code> content
attribute of any <span title="HTML elements">HTML element</span> in
the <span>active document</span> with an <code
title="attr-id">id</code> content attribute.</li>
</ul>
<p>When <dfn title="dom-window-namedItem">the <code>Window</code>
object is indexed for property retrieval</dfn> using a name <var
title="">name</var>, then the user agent must return the value
obtained using the following steps:</p>
<ol>
<li>
<p>Let <var title="">elements</var> be the list of <span
title="dom-window-namedItem-filter">named elements</span> with the
name <var title="">name</var> in the <span>active document</span>.
<p class="note">There will be at least one such element, by
definition.<!-- (If there wasn't, then this algorithm wouldn't
have been invoked by Web IDL.) --></p>
</li>
<li>
<p>If <var title="">elements</var> contains an <code>iframe</code>
element, then return the <code>WindowProxy</code> object of the
<span>nested browsing context</span> represented by the first such
<code>iframe</code> element in <span>tree order</span>, and abort
these steps.</p>
</li>
<li>
<p>Otherwise, if <var title="">elements</var> has only one
element, return that element and abort these steps.</p>
</li>
<li>
<p>Otherwise return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only <span
title="dom-window-namedItem-filter">named elements</span> with
the name <var title="">name</var>.</p> <!-- the same one each time
is returned, because of the rule under collections -->
</li>
</ol>
<p><dfn title="dom-window-nameditem-filter">Named elements</dfn>
with the name <var title="">name</var>, for the purposes of the
above algorithm, are those that are either:</p>
<ul>
<li><code>a</code>, <code>applet</code>, <code>area</code>,
<code>embed</code>, <code>form</code>, <code>frame</code>,
<code>frameset</code>, <code>iframe</code>, <code>img</code>, or
<code>object</code> elements that have a <code
title="attr-name">name</code> content attribute whose value is <var
title="">name</var>, or</li>
<li><span>HTML elements</span> elements that have an <code
title="attr-id">id</code> content attribute whose value is <var
title="">name</var>.</li>
</ul>
</div>
<div class="impl">
<h4>Garbage collection and browsing contexts</h4>
<p>A <span>browsing context</span> has a strong reference to each of
its <code>Document</code>s and its <code>WindowProxy</code> object,
and the user agent itself has a strong reference to its <span
title="top-level browsing context">top-level browsing
contexts</span>.</p>
<p>A <code>Document</code> has a strong reference to each of its
<span title="view">views</span> and their <code>AbstractView</code>
objects.</p>
<p>When a <span>browsing context</span> is to <dfn>discard a
<code>Document</code></dfn>, that means that it is to lose the
strong reference from the <code>Document</code>'s <span>browsing
context</span> to the <code>Document</code>, and that any <span
title="concept-task">tasks</span> associated with the
<code>Document</code> in any <span>task source</span> must be
removed without being run.</p>
<p class="note">The <span>browsing context</span>'s <span>default
view</span>'s <code>Window</code> object <span title="implied strong
reference">has a strong reference</span> to its
<code>Document</code> object through the <code
title="dom-document">document</code> attribute of the
<code>AbstractView</code> interface. Thus, references from other
scripts to either of those objects will keep both alive. <a
href="#refsDOMVIEWS">[DOMVIEWS]</a></p>
<p class="note">Whenever a <code>Document</code> object is <span
title="discard a Document">discarded</span>, it is also removed from
the list of <span>the worker's <code>Document</code>s</span> of each
worker whose list contains that <code>Document</code>.</p>
<p>When <dfn>a <em><span>browsing context</span></em> is
discarded</dfn>, the strong reference from the user agent itself to
the <span>browsing context</span> must be severed, and all the
<code>Document</code> objects for all the entries in the
<span>browsing context</span>'s session history must be <span
title="discard a document">discarded</span> as well.</p>
<p>User agents may <span title="a browsing context is
discarded">discard</span> <span title="top-level browsing
context">top-level browsing contexts</span> at any time (typically,
in response to user requests, e.g. when a user closes a window
containing one or more <span title="top-level browsing
context">top-level browsing contexts</span>). Other <span
title="browsing context">browsing contexts</span> must be discarded
once their <code>WindowProxy</code> object is eligible for garbage
collection.</p>
</div>
<h4>Browser interface elements</h4>
<p>To allow Web pages to integrate with Web browsers, certain Web
browser interface elements are exposed in a limited way to scripts
in Web pages.</p>
<p>Each interface element is represented by a <code>BarProp</code>
object:</p>
<pre class="idl">interface <dfn>BarProp</dfn> {
attribute boolean <span title="dom-BarProp-visible">visible</span>;
};</pre>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-window-locationbar">locationbar</code> . <code title="dom-BarProp-visible">visible</code></dt>
<dd>
<p>Returns true if the location bar is visible; otherwise, returns false.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-window-menubar">menubar</code> . <code title="dom-BarProp-visible">visible</code></dt>
<dd>
<p>Returns true if the menu bar is visible; otherwise, returns false.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-window-personalbar">personalbar</code> . <code title="dom-BarProp-visible">visible</code></dt>
<!--<dt><var title="">window</var> . <code title="dom-window-directories">directories</code> . <code title="dom-BarProp-visible">visible</code></dt>-->
<dd>
<p>Returns true if the personal bar is visible; otherwise, returns false.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-window-scrollbars">scrollbars</code> . <code title="dom-BarProp-visible">visible</code></dt>
<dd>
<p>Returns true if the scroll bars are visible; otherwise, returns false.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-window-statusbar">statusbar</code> . <code title="dom-BarProp-visible">visible</code></dt>
<dd>
<p>Returns true if the status bar is visible; otherwise, returns false.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-window-toolbar">toolbar</code> . <code title="dom-BarProp-visible">visible</code></dt>
<dd>
<p>Returns true if the toolbar is visible; otherwise, returns false.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-BarProp-visible">visible</dfn> attribute, on
getting, must return either true or a value determined by the user
agent to most accurately represent the visibility state of the user
interface element that the object represents, as described below. On
setting, the new value must be discarded.</p>
<p>The following <code>BarProp</code> objects exist for each
<code>Document</code> object in a <span>browsing
context</span>. Some of the user interface elements represented by
these objects might have no equivalent in some user agents; for
those user agents, except when otherwise specified, the object must
act as if it was present and visible (i.e. its <code
title="dom-BarProp-visible">visible</code> attribute must return
true).</p>
<dl>
<dt><dfn>The location bar <code>BarProp</code> object</dfn></dt>
<dd>Represents the user interface element that contains a control
that displays the <span>URL</span> of the <span>active
document</span>, or some similar interface concept.</dd>
<dt><dfn>The menu bar <code>BarProp</code> object</dfn></dt>
<dd>Represents the user interface element that contains a list of
commands in menu form, or some similar interface concept.</dd>
<dt><dfn>The personal bar <code>BarProp</code> object</dfn></dt>
<dd>Represents the user interface element that contains links to
the user's favorite pages, or some similar interface concept.</dd>
<dt><dfn>The scrollbar <code>BarProp</code> object</dfn></dt>
<dd>Represents the user interface element that contains a scrolling
mechanism, or some similar interface concept.</dd>
<dt><dfn>The status bar <code>BarProp</code> object</dfn></dt>
<dd>Represents a user interface element found immediately below or
after the document, as appropriate for the <span>default
view</span>'s media. If the user agent has no such user interface
element, then the object may act as if the corresponding user
interface element was absent (i.e. its <code
title="dom-BarProp-visible">visible</code> attribute may return
false).</dd>
<dt><dfn>The toolbar <code>BarProp</code> object</dfn></dt>
<dd>Represents the user interface element found immediately above
or before the document, as appropriate for the <span>default
view</span>'s media. If the user agent has no such user interface
element, then the object may act as if the corresponding user
interface element was absent (i.e. its <code
title="dom-BarProp-visible">visible</code> attribute may return
false).</dd>
</dl>
<p>The <dfn
title="dom-window-locationbar"><code>locationbar</code></dfn>
attribute must return <span>the location bar <code>BarProp</code>
object</span>.</p>
<p>The <dfn title="dom-window-menubar"><code>menubar</code></dfn>
attribute must return <span>the menu bar <code>BarProp</code>
object</span>.</p>
<p>The <dfn
title="dom-window-personalbar"><code>personalbar</code></dfn>
attribute must return <span>the personal bar <code>BarProp</code>
object</span>.</p>
<p>The <dfn
title="dom-window-scrollbars"><code>scrollbars</code></dfn>
attribute must return <span>the scrollbar <code>BarProp</code>
object</span>.</p>
<p>The <dfn
title="dom-window-statusbar"><code>statusbar</code></dfn> attribute
must return <span>the status bar <code>BarProp</code>
object</span>.</p>
<p>The <dfn title="dom-window-toolbar"><code>toolbar</code></dfn>
attribute must return <span>the toolbar <code>BarProp</code>
object</span>.</p>
<!--
<p>For legacy reasons, the <dfn
title="dom-window-directories"><code>directories</code></dfn>
attribute must also return <span>the personal bar
<code>BarProp</code> object</span>.</p>
-->
</div>
<div class="impl">
<h3>Origin</h3>
<!-- Hallowed are the Ori -->
<p>The <dfn>origin</dfn> of a resource and the <dfn>effective script
origin</dfn> of a resource are both either opaque identifiers or
tuples consisting of a scheme component, a host component, a port
component, and optionally extra data.</p>
<p class="note">The extra data could include the certificate of the
site when using encrypted connections, to ensure that if the site's
secure certificate changes, the origin is considered to change as
well.</p>
<p>These characteristics are defined as follows:</p>
<dl>
<dt>For URLs</dt>
<dd>
<p>The <span>origin</span> and <span>effective script
origin</span> of the <span>URL</span> is whatever is returned by
the following algorithm:</p>
<ol>
<li><p>Let <var title="">url</var> be the <span>URL</span> for
which the <span>origin</span> is being determined.</p></li>
<li><p><span title="parse a url">Parse</span> <var
title="">url</var>.</p></li>
<li><p>If <var title="">url</var> identifies a resource that is
its own trust domain (e.g. it identifies an e-mail on an IMAP
server or a post on an NNTP server) then return a globally unique
identifier specific to the resource identified by <var
title="">url</var>, so that if this algorithm is invoked again
for <span title="URL">URLs</span> that identify the same resource,
the same identifier will be returned.</p></li>
<li><p>If <var title="">url</var> does not use a server-based
naming authority, or if parsing <var title="">url</var> failed,
or if <var title="">url</var> is not an <span>absolute
URL</span>, then return a new globally unique
identifier.</p></li>
<li><p>Let <var title="">scheme</var> be the <span
title="url-scheme"><scheme></span> component of <var
title="">url</var>, <span>converted to ASCII lowercase</span>.</p></li>
<li><p>If the UA doesn't support the protocol given by <var
title="">scheme</var>, then return a new globally unique
identifier.</p></li>
<li><p>If <var title="">scheme</var> is "<code
title="">file</code>", then the user agent may return a
UA-specific value.</p></li>
<li><p>Let <var title="">host</var> be the <span
title="url-host"><host></span> component of <var
title="">url</var>.</p></li>
<li>
<p>Apply the IDNA ToASCII algorithm to <var title="">host</var>,
with both the AllowUnassigned and UseSTD3ASCIIRules flags
set. Let <var title="">host</var> be the result of the ToASCII
algorithm.</p>
<p>If ToASCII fails to convert one of the components of the
string, e.g. because it is too long or because it contains
invalid characters, then return a new globally unique
identifier. <a href="#refsRFC3490">[RFC3490]</a></p>
</li>
<li><p>Let <var title="">host</var> be the result of converting
<var title="">host</var> <span title="converted to ASCII lowercase">to
ASCII lowercase</span>.</p></li>
<li><p>If there is no <span title="url-port"><port></span>
component, then let <var title="">port</var> be the default port
for the protocol given by <var title="">scheme</var>. Otherwise,
let <var title="">port</var> be the <span
title="url-port"><port></span> component of <var
title="">url</var>.</p></li>
<li><p>Return the tuple (<var title="">scheme</var>, <var
title="">host</var>, <var title="">port</var>).</p></li>
</ol>
<p>In addition, if the <span>URL</span> is in fact associated with
a <code>Document</code> object that was created by parsing the
resource obtained from fetching <span>URL</span>, and this was
done over a secure connection, then the server's secure
certificate may be added to the origin as additional data.</p>
</dd>
<dt>For scripts</dt>
<dd>
<p>The <span>origin</span> and <span>effective script
origin</span> of a script are determined from another resource,
called the <i>owner</i>:</p>
<dl class="switch">
<dt>If a script is in a <code>script</code> element</dt>
<dd>The owner is the <code>Document</code> to which the
<code>script</code> element belongs.</dd>
<dt>If a script is in an <span title="event handler content
attributes">event handler content attribute</span></dt>
<dd>The owner is the <code>Document</code> to which the
attribute node belongs.</dd>
<dt>If a script is a function or other code reference created by
another script</dt>
<dd>The owner is the script that created it.</dd>
<dt>If a script is a <span title="javascript protocol"><code
title="">javascript:</code> URL</span> that was returned as the
location of an HTTP redirect (<span
title="concept-http-equivalent-codes">or equivalent</span> in
other protocols)</dt>
<dd>The owner is the <span>URL</span> that redirected to the
<span title="javascript protocol"><code
title="">javascript:</code> URL</span>.</dd>
<dt>If a script is a <span title="javascript protocol"><code
title="">javascript:</code> URL</span> in an attribute</dt>
<dd>The owner is the <code>Document</code> of the element on
which the attribute is found.</dd>
<dt>If a script is a <span title="javascript protocol"><code
title="">javascript:</code> URL</span> in a style sheet</dt>
<dd>The owner is the <span>URL</span> of the style sheet.</dd>
<dt>If a script is a <span title="javascript protocol"><code
title="">javascript:</code> URL</span> to which a <span>browsing
context</span> is being <span title="navigate">navigated</span>,
the URL having been provided by the user (e.g. by using a
<i>bookmarklet</i>)</dt>
<dd>The owner is the <code>Document</code> of the <span>browsing
context</span>'s <span>active document</span>.</dd>
<dt>If a script is a <span title="javascript protocol"><code
title="">javascript:</code> URL</span> to which a <span>browsing
context</span> is being <span title="navigate">navigated</span>,
the URL having been declared in markup</dt>
<dd>The owner is the <code>Document</code> of the element
(e.g. an <code>a</code> or <code>area</code> element) that
declared the URL.</dd>
<dt>If a script is a <span title="javascript protocol"><code
title="">javascript:</code> URL</span> to which a <span>browsing
context</span> is being <span title="navigate">navigated</span>,
the URL having been provided by script</dt>
<dd>The owner is the script that provided the URL.</dd>
</dl>
<p>The <span>origin</span> of the script is then equal to the
<span>origin</span> of the owner, and the <span>effective script
origin</span> of the script is equal to the <span>effective script
origin</span> of the owner.</p>
</dd>
<dt>For <code>Document</code> objects and images</dt>
<dd>
<dl class="switch">
<dt id="sandboxOrigin">If a <code>Document</code> is in a
<span>browsing context</span> whose <span>sandboxed origin
browsing context flag</span> was set when the
<code>Document</code> was created</dt>
<dd>The <span>origin</span> is a globally unique identifier
assigned when the <code>Document</code> is created.</dd>
<dt>If a <code>Document</code> or image was returned by the
<code>XMLHttpRequest</code> API</dt>
<dd>The <span>origin</span> is equal to the <span>XMLHttpRequest
origin</span> of the <code>XMLHttpRequest</code> object. <a
href="#refsXHR">[XHR]</a></dd>
<dt>If a <code>Document</code> or image was generated from a
<span title="javascript protocol"><code>javascript:</code>
URL</span></dt>
<dd>The <span>origin</span> is equal to the <span>origin</span>
of the script of that <span title="javascript
protocol"><code>javascript:</code> URL</span>.</dd>
<dt>If a <code>Document</code> or image was served over the
network and has an address that uses a URL scheme with a
server-based naming authority</dt>
<dd>The <span>origin</span> is the <span>origin</span> of the
<span title="the document's address">address</span> of the
<code>Document</code> or the <span>URL</span> of the image, as
appropriate.</dd>
<dt>If a <code>Document</code> or image was generated from a
<code title="">data:</code> URL that was returned as the location
of an HTTP redirect (<span
title="concept-http-equivalent-codes">or equivalent</span> in
other protocols)</dt>
<dd>The <span>origin</span> is the <span>origin</span> of the
<span>URL</span> that redirected to the <code
title="">data:</code> URL.</dd>
<dt>If a <code>Document</code> or image was generated from a
<code title="">data:</code> URL found in another
<code>Document</code> or in a script</dt>
<dd>The <span>origin</span> is the <span>origin</span> of the
<code>Document</code> or script in which the <code
title="">data:</code> URL was found.</dd>
<dt>If a <code>Document</code> has the <span title="the
document's address">address</span>
"<code>about:blank</code>"</dt>
<dd>The <span>origin</span> of the <code>Document</code> is <a
href="#about-blank-origin">the <span>origin</span> it was
assigned when its browsing context was created</a>.</dd>
<dt>If a <code>Document</code> or image was obtained in some
other manner (e.g. a <code title="">data:</code> URL typed in by
the user, a <code>Document</code> created using the <code
title="dom-DOMImplementation-createDocument">createDocument()</code>
API, etc)</dt>
<dd>The <span>origin</span> is a globally unique identifier
assigned when the <code>Document</code> or image is created.</dd>
</dl>
<p>When a <code>Document</code> is created, its <span>effective
script origin</span> is initialized to the <span>origin</span> of
the <code>Document</code>. However, the <code
title="dom-document-domain">document.domain</code> attribute can
be used to change it.</p>
</dd>
<dt>For <code>audio</code> and <code>video</code> elements</dt>
<dd>
<p>If value of the <span>media element</span>'s <code
title="dom-media-currentSrc">currentSrc</code> attribute is the
empty string, the <span>origin</span> is the same as the
<span>origin</span> of the element's <code>Document</code>'s
<span>origin</span>.</p>
<p>Otherwise, the <span>origin</span> is equal to the
<span>origin</span> of the <span>absolute URL</span> given by the
<span>media element</span>'s <code
title="dom-media-currentSrc">currentSrc</code> attribute.</p>
</dd>
</dl>
<p>The <dfn>Unicode serialization of an origin</dfn> is the string
obtained by applying the following algorithm to the given
<span>origin</span>:</p>
<ol>
<li><p>If the <span>origin</span> in question is not a
scheme/host/port tuple, then return the literal string "<code
title="">null</code>" and abort these steps.</p></li>
<li><p>Otherwise, let <var title="">result</var> be the scheme part
of the <span>origin</span> tuple.</p></li>
<li><p>Append the string "<code title="">://</code>" to <var
title="">result</var>.</p></li>
<li><p>Apply the IDNA ToUnicode algorithm to each component of the
host part of the <span>origin</span> tuple, and append the results
— each component, in the same order, separated by U+002E FULL
STOP characters (.) — to <var title="">result</var>. <a
href="#refsRFC3490">[RFC3490]</a></p></li>
<li><p>If the port part of the <span>origin</span> tuple gives a port
that is different from the default port for the protocol given by
the scheme part of the <span>origin</span> tuple, then append a
U+003A COLON character (:) and the given port, in base ten, to
<var title="">result</var>.</p></li>
<li><p>Return <var title="">result</var>.</p></li>
</ol>
<p>The <dfn>ASCII serialization of an origin</dfn> is the string
obtained by applying the following algorithm to the given
<span>origin</span>:</p>
<ol>
<li><p>If the <span>origin</span> in question is not a
scheme/host/port tuple, then return the literal string "<code
title="">null</code>" and abort these steps.</p></li>
<li><p>Otherwise, let <var title="">result</var> be the scheme part
of the <span>origin</span> tuple.</p></li>
<li><p>Append the string "<code title="">://</code>" to <var
title="">result</var>.</p></li>
<li>
<p>Apply the IDNA ToASCII algorithm the host part of the
<span>origin</span> tuple, with both the AllowUnassigned and
UseSTD3ASCIIRules flags set, and append the results <var
title="">result</var>.</p>
<p>If ToASCII fails to convert one of the components of the
string, e.g. because it is too long or because it contains invalid
characters, then return the empty string and abort these steps. <a
href="#refsRFC3490">[RFC3490]</a></p>
</li>
<li><p>If the port part of the <span>origin</span> tuple gives a port
that is different from the default port for the protocol given by
the scheme part of the <span>origin</span> tuple, then append a
U+003A COLON character (:) and the given port, in base ten, to
<var title="">result</var>.</p></li>
<li><p>Return <var title="">result</var>.</p></li>
</ol>
<p>Two <span title="origin">origins</span> are said to be the
<dfn>same origin</dfn> if the following algorithm returns true:</p>
<ol>
<li><p>Let <var title="">A</var> be the first <span>origin</span>
being compared, and <var title="">B</var> be the second
<span>origin</span> being compared.</p></li>
<li><p>If <var title="">A</var> and <var title="">B</var> are both
opaque identifiers, and their value is equal, then return
true.</p></li>
<li><p>Otherwise, if either <var title="">A</var> or <var
title="">B</var> or both are opaque identifiers, return
false.</p></li>
<li><p>If <var title="">A</var> and <var title="">B</var> have
scheme components that are not identical, return false.</p></li>
<li><p>If <var title="">A</var> and <var title="">B</var> have host
components that are not identical, return false.</p></li>
<li><p>If <var title="">A</var> and <var title="">B</var> have port
components that are not identical, return false.</p></li>
<li><p>If either <var title="">A</var> or <var title="">B</var>
have additional data, but that data is not identical for both,
return false.</p></li>
<li><p>Return true.</p></li>
</ol>
</div>
<h4>Relaxing the same-origin restriction</h4>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-domain">domain</code> [ = <var title="">domain</var> ]</dt>
<dd>
<p>Returns the current domain used for security checks.</p>
<p>Can be set to a value that removes subdomains, to allow pages
on other subdomains of the same domain (if they do the same thing)
to access each other.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-document-domain"><code>domain</code></dfn>
attribute on <code>Document</code> objects must be initialized to
<span>the document's domain</span>, if it has one, and the empty
string otherwise. If the value is an IPv6 address, then the square
brackets from the host portion of the <span
title="url-host"><host></span> component must be omitted from
the attribute's value.</p>
<p>On getting, the attribute must return its current
value, unless the document was created by
<code>XMLHttpRequest</code>, in which case it must throw an
<code>INVALID_ACCESS_ERR</code> exception.</p>
<p>On setting, the user agent must run the following algorithm:</p>
<ol>
<li>
<p>If the document was created by <code>XMLHttpRequest</code>,
throw an <code>INVALID_ACCESS_ERR</code> exception and abort these
steps.</p>
</li>
<li>
<p>If the new value is an IP address, let <var title="">new
value</var> be the new value. Otherwise, apply the IDNA ToASCII
algorithm to the new value, with both the AllowUnassigned and
UseSTD3ASCIIRules flags set, and let <var title="">new value</var>
be the result of the ToASCII algorithm.</p>
<p>If ToASCII fails to convert one of the components of the
string, e.g. because it is too long or because it contains invalid
characters, then throw a <code>SECURITY_ERR</code> exception and abort
these steps. <a href="#refsRFC3490">[RFC3490]</a></p>
</li>
<li>
<p>If <var title="">new value</var> is not exactly equal to the
current value of the <code
title="dom-document-domain">document.domain</code> attribute, then
run these substeps:</p>
<ol>
<li>
<p>If the current value is an IP address, throw a
<code>SECURITY_ERR</code> exception and abort these steps.</p>
</li>
<li>
<p>If <var title="">new value</var>, prefixed by a U+002E FULL
STOP (.), does not exactly match the end of the current value,
throw a <code>SECURITY_ERR</code> exception and abort these
steps.</p>
</li>
<li>
<p>If <var title="">new value</var> matches a suffix in the
Public Suffix List, or, if <var title="">new value</var>,
prefixed by a U+002E FULL STOP (.), matches the end of a
suffix in the Public Suffix List, then throw a
<code>SECURITY_ERR</code> exception and abort these steps. <a
href="#refsPSL">[PSL]</a></p>
<p>Suffixes must be compared after applying the IDNA ToASCII
algorithm to them, with both the AllowUnassigned and
UseSTD3ASCIIRules flags set, in an <span>ASCII
case-insensitive</span> manner. <a
href="#refsRFC3490">[RFC3490]</a></p>
</li>
</ol>
</li>
<li><p>Release the <span>storage mutex</span>.</p></li>
<li>
<p>Set the attribute's value to <var title="">new value</var>.</p>
</li>
<li>
<p>Set the host part of the <span>effective script origin</span>
tuple of the <code>Document</code> to <var title="">new
value</var>.</p>
</li>
<li>
<p>Set the port part of the <span>effective script origin</span>
tuple of the <code>Document</code> to "manual override" (a value
that, for the purposes of <span title="same origin">comparing
origins</span>, is identical to "manual override" but not
identical to any other value).</p>
</li>
</ol>
<p>The <dfn title="the document's domain">domain</dfn> of a
<code>Document</code> is the host part of the document's
<span>origin</span>, if that is a scheme/host/port tuple. If it
isn't, then the document does not have a domain.</p>
</div>
<p class="note">The <code title="dom-document-domain">domain</code>
attribute is used to enable pages on different hosts of a domain to
access each others' DOMs.</p>
<p class="warning">Do not use the <code
title="dom-document-domain">document.domain</code> attribute when
using shared hosting. If an untrusted third party is able to host an
HTTP server at the same IP address but on a different port, then the
same-origin protection that normally protects two different sites on
the same host will fail, as the ports are ignored when comparing
origins after the <code
title="dom-document-domain">document.domain</code> attribute has
been used.</p>
<h3 id="scripting">Scripting</h3>
<h4>Introduction</h4>
<p>Various mechanisms can cause author-provided executable code to
run in the context of a document. These mechanisms include, but are
probably not limited to:</p>
<ul>
<li>Processing of <code>script</code> elements.</li>
<li>Processing of inline <code title="javascript
protocol">javascript:</code> URLs (e.g. the <code
title="attr-img-src">src</code> attribute of <code>img</code>
elements, or an <code title="">@import</code> rule in a CSS
<code>style</code> element block).</li>
<li>Event handlers, whether registered through the DOM using <code
title="">addEventListener()</code>, by explicit <span>event handler
content attributes</span>, by <span>event handler IDL
attributes</span>, or otherwise.</li>
<li>Processing of technologies like XBL or SVG that have their own
scripting features.</li>
</ul>
<div class="impl">
<h4>Enabling and disabling scripting</h4>
<p><dfn title="concept-bc-script">Scripting is enabled</dfn> in a
<em><span>browsing context</span></em> when all of the
following conditions are true:</p>
<ul>
<li>The user agent supports scripting.</li>
<li>The user has not disabled scripting for this <span>browsing
context</span> at this time. (User agents may provide users with
the option to disable scripting globally, or in a finer-grained
manner, e.g. on a per-origin basis.)</li>
<li id="sandboxScriptBlocked">The <span>browsing context</span>
does not have the <span>sandboxed scripts browsing context
flag</span> set.</li>
</ul>
<p><dfn title="concept-bc-noscript">Scripting is disabled</dfn> in a
<span>browsing context</span> when any of the above conditions are
false (i.e. when scripting is not <span
title="concept-bc-script">enabled</span>).</p>
<hr>
<p><dfn title="concept-n-script">Scripting is enabled</dfn> for a
<em>node</em> if the <code>Document</code> object of the node (the
node itself, if it is itself a <code>Document</code> object) has an
associated <span>browsing context</span>, and <span
title="concept-bc-script">scripting is enabled</span> in that
<span>browsing context</span>.</p>
<p><dfn title="concept-n-noscript">Scripting is disabled</dfn> for a
node if there is no such <span>browsing context</span>, or if <span
title="concept-bc-noscript">scripting is disabled</span> in that
<span>browsing context</span>.</p>
</div>
<div class="impl">
<!-- SCRIPT EXEC (marks areas related to creation of scripts) -->
<h4>Processing model</h4>
<h5>Definitions</h5>
<p>A <dfn title="concept-script">script</dfn> has:</p>
<dl>
<dt>A <dfn>script execution environment</dfn></dt>
<dd>
<p>The characteristics of the script execution environment depend
on the language, and are not defined by this specification.</p>
<p class="example">In JavaScript, the script execution environment
consists of the interpreter, the stack of <i>execution
contexts</i>, the <i>global code</i> and <i>function code</i> and
the Function objects resulting, and so forth.</p>
</dd>
<dt>A <dfn>list of code entry-points</dfn></dt>
<dd>
<p>Each code entry-point represents a block of executable code
that the script exposes to other scripts and to the user
agent.</p>
<p class="example">Each Function object in a JavaScript
<span>script execution environment</span> has a corresponding code
entry-point, for instance.</p>
<p>The main program code of the script, if any, is the
<dfn><i>initial code entry-point</i></dfn>. Typically, the code
corresponding to this entry-point is executed immediately after
the script is parsed.</p>
<p class="example">In JavaScript, this corresponds to the
execution context of the global code.</p>
</dd>
<dt>A relationship with the <dfn>script's global object</dfn></dt>
<dd>
<p>An object that provides the APIs that the code can use.</p>
<p class="example">This is typically a <code>Window</code>
object. In JavaScript, this corresponds to the <i>global
object</i>.</p>
<p class="note">When a <span>script's global object</span> is an
empty object, it can't do anything that interacts with the
environment.</p>
<p>If the <span>script's global object</span> is a
<code>Window</code> object, then in JavaScript, the <code
title="">this</code> keyword in the global scope must return the
<code>Window</code> object's <code>WindowProxy</code> object.</p>
<p class="note">This is a <span>willful violation</span> of the
JavaScript specification current at the time of writing
(ECMAScript edition 3). The JavaScript specification requires that
the <code title="">this</code> keyword in the global scope return
the global object, but this is not compatible with the security
design prevalent in implementations as specified herein. <a
href="#refsECMA262">[ECMA262]</a></p>
</dd>
<dt>A relationship with the <dfn>script's browsing context</dfn></dt>
<dd>
<p>A <span>browsing context</span> that is assigned responsibility
for actions taken by the script.</p>
<p class="example">When a script creates and <span
title="navigate">navigates</span> a new <span>top-level browsing
context</span>, the <code title="dom-opener">opener</code>
attribute of the new <span>browsing context</span>'s
<code>Window</code> object will be set to the <span>script's
browsing context</span>'s <code>WindowProxy</code> object.</p>
</dd>
<dt>A <dfn title="script's URL character encoding">URL character encoding</dfn></dt>
<dd>
<p>A character encoding, set when the script is created, used to
encode URLs. <span id="sce-not-copy">If the character encoding is
set from another source, e.g. a <span>document's character
encoding</span>, then the <span>script's URL character
encoding</span> must follow the source, so that if the source's
changes, so does the script's.</span></p>
</dd>
<dt>A <dfn title="script's base URL">base URL</dfn></dt>
<dd>
<p>A <span>URL</span>, set when the script is created, used to
resolve relative URLs. <span id="sbu-not-copy">If the base URL is
set from another source, e.g. a <span>document base URL</span>,
then the <span>script's base URL</span> must follow the source, so
that if the source's changes, so does the script's.</span></p>
</dd>
</dl>
</div>
<div class="impl">
<h5>Calling scripts</h5>
<p>When a user agent is to <dfn>jump to a code entry-point</dfn> for
a <span title="concept-script">script</span>, for example to invoke
an event listener defined in that <span
title="concept-script">script</span>, the user agent must run the
following steps:</p>
<ol>
<li><p>If the <span>script's global object</span> is a
<code>Window</code> object whose <code>Document</code> object is
not <span>fully active</span>, then abort these steps without doing
anything. The callback is not fired.</p>
<li><p>Set the <span>first script</span> to be the <span
title="concept-script">script</span> being invoked.</p></li>
<li><p>Make the <span title="script execution environment">script
execution environment</span> for the <span
title="concept-script">script</span> execute the code for the given
code entry-point.</p></li>
<li><p>Set the <span>first script</span> back to whatever it was
when this algorithm started.</p></li>
</ol>
<p>This algorithm is not invoked by one script calling another.</p>
</div>
<div class="impl">
<h5 id="creating-scripts">Creating scripts</h5>
<p>When the specification says that a <span
title="concept-script">script</span> is to be <dfn title="create a
script">created</dfn>, given some script source, its scripting
language, a global object, a browsing context, a URL character
encoding, and a base URL, the user agent must run the following
steps:</p>
<ol>
<li><p>If <span title="concept-bc-noscript">scripting is
disabled</span> for <span>browsing context</span> passed to this
algorithm, then abort these steps, as if the script did nothing but
return void.</p>
<li><p>Set up a <span>script execution environment</span> as
appropriate for the scripting language.</p></li>
<li><p>Parse/compile/initialize the source of the script using the
<span>script execution environment</span>, as appropriate for the
scripting language, and thus obtain the <span>list of code
entry-points</span> for the script. If the semantics of the
scripting language and the given source code are such that there is
executable code to be immediately run, then the <i>initial code
entry-point</i> is the entry-point for that code.</p></li>
<li><p>Set up the <span>script's global object</span>, the
<span>script's browsing context</span>, the <span>script's URL
character encoding</span>, and the <span>script's base URL</span>
from the settings passed to this algorithm.</p></li>
<li><p><span title="jump to a code entry-point">Jump</span> to the
<span title="concept-script">script</span>'s <i>initial code
entry-point</i>.</p></li>
</ol>
<hr>
<p>When the user agent is to <dfn>create an impotent script</dfn>,
given some script source, its scripting language, and a browsing
context, the user agent must <span>create a script</span>, using the
given script source and scripting language, using a new empty object
as the global object, and using the given browsing context as the
browsing context. The URL character encoding and base URL for the
resulting <span title="concept-script">script</span> are not
important as no APIs are exposed to the script.</p>
<hr>
<p>When the specification says that a <span
title="concept-script">script</span> is to be <dfn title="create a
script from a node">created from a node</dfn> <var
title="">node</var>, given some script source and its scripting
language, the user agent must <span>create a script</span>, using
the given script source and scripting language, and using <span>the
script settings determined from the node</span> <var
title="">node</var>.</p>
<p><dfn>The script settings determined from the node</dfn> <var
title="">node</var> are computed as follows:</p>
<ol>
<li><p>Let <var title="">document</var> be the
<code>Document</code> of <var title="">node</var> (or <var
title="">node</var> itself if it is a
<code>Document</code>).</p></li>
<li><p>The browsing context is the <span>browsing context</span> of
<var title="">document</var>.</p>
<li><p>The global object is the <code>Window</code> object of
<var title="">document</var>.</p></li>
<li><p>The URL character encoding is the <span title="document's
character encoding">character encoding</span> of <var
title="">document</var>. (<a href="#sce-not-copy">This is a
reference, not a copy</a>.)</p></li>
<li><p>The base URL is the <span title="document base URL">base
URL</span> of <var title="">document</var>. (<a
href="#sbu-not-copy">This is a reference, not a copy</a>.)</p></li>
</ol>
</div>
<div class="impl">
<h5>Killing scripts</h5>
<p>User agents may impose resource limitations on scripts, for
example CPU quotas, memory limits, total execution time limits, or
bandwidth limitations. When a script exceeds a limit, the user agent
may either throw a <code>QUOTA_EXCEEDED_ERR</code> exception, abort
the script without an exception, prompt the user, or throttle script
execution.</p>
<div class="example">
<p>For example, the following script never terminates. A user agent
could, after waiting for a few seconds, prompt the user to either
terminate the script or let it continue.</p>
<pre><script>
while (true) { /* loop */ }
</script></pre>
</div>
<p>User agents are encouraged to allow users to disable scripting
whenever the user is prompted either by a script (e.g. using the
<code title="dom-alert">window.alert()</code> API) or because of a
script's actions (e.g. because it has exceeded a time limit).</p>
<p>If scripting is disabled while a script is executing, the script
should be terminated immediately.</p>
</div>
<div class="impl">
<h4>Event loops</h4>
<h5>Definitions</h5>
<p>To coordinate events, user interaction, scripts, rendering,
networking, and so forth, user agents must use <dfn title="event
loop">event loops</dfn> as described in this section.</p>
<p>There must be at least one <span>event loop</span> per user
agent, and at most one <span>event loop</span> per <span>unit of
related similar-origin browsing contexts</span>.</p>
<p>An <span>event loop</span> always has at least one <span>browsing
context</span>. If an <span>event loop</span>'s <span
title="browsing context">browsing contexts</span> all go away, then
the <span>event loop</span> goes away as well. A <span>browsing
context</span> always has an <span>event loop</span> coordinating
its activities.</p>
<!--END complete-->
<p class="note">Other specifications can define new kinds of event
loops that aren't associated with browsing contexts; in particular,
the Web Workers specification does so.</p>
<!--START complete-->
<p>An <span>event loop</span> has one or more <dfn title="task
queue">task queues</dfn>. A <span>task queue</span> is an ordered
list of <dfn title="concept-task">tasks</dfn>, which can be:</p>
<dl>
<dt>Events</dt>
<dd>
<p>Asynchronously dispatching an <code>Event</code> object at a
particular <code>EventTarget</code> object is a task.</p>
<p class="note">Not all events are dispatched using the <span>task
queue</span>, many are dispatched synchronously during other
tasks.</p>
</dd>
<dt>Parsing</dt>
<dd><p>The <span>HTML parser</span> tokenizing a single byte, and
then processing any resulting tokens, is a task.</p></dd>
<dt>Callbacks</dt>
<dd><p>Calling a callback asynchronously is a task.</p></dd>
<dt>Using a resource</dt>
<dd><p>When an algorithm <span title="fetch">fetches</span> a
resource, if the fetching occurs asynchronously then the processing
of the resource once some or all of the resource is available is a
task.</p></dd>
<dt>Reacting to DOM manipulation</dt>
<dd><p>Some elements have tasks that trigger in response to DOM
manipulation, e.g. when that element is <span title="insert an
element into a document">inserted into the document</span>.</p>
</dl>
<p>When a user agent is to <dfn>queue a task</dfn>, it must add the
given task to one of the <span title="task queue">task queues</span>
of the relevant <span>event loop</span>. All the tasks from one
particular <dfn>task source</dfn> (e.g. the callbacks generated by
timers, the events dispatched for mouse movements, the tasks queued
for the parser) must always be added to the same <span>task
queue</span>, but tasks from different <span title="task
source">task sources</span> may be placed in different <span
title="task queue">task queues</span>.</p>
<p class="example">For example, a user agent could have one
<span>task queue</span> for mouse and key events (the <span>user
interaction task source</span>), and another for everything
else. The user agent could then give keyboard and mouse events
preference over other tasks three quarters of the time, keeping the
interface responsive but not starving other task queues, and never
processing events from any one <span>task source</span> out of
order.</p>
<p>Each <span title="concept-task">task</span> that is <span
title="queue a task">queued</span> onto a <span>task queue</span> of
an <span>event loop</span> defined by this specification is
associated with a <code>Document</code>; if the task was queued in
the context of an element, then it is the element's
<code>Document</code>; if the task was queued in the context of a
<span>browsing context</span>, then it is the <span>browsing
context</span>'s <span>active document</span> at the time the task
was queued; if the task was queued by or for a <span
title="concept-script">script</span> then the document is the
<span>script's browsing context</span>'s <span>active
document</span> at the time the task was queued.</p>
<p>A user agent is required to have one <dfn>storage
mutex</dfn>. This mutex is used to control access to shared state
like cookies. At any one point, the <span>storage mutex</span> is
either free, or owned by a particular <span>event loop</span> or
instance of the <span title="fetch">fetching</span> algorithm.</p>
<p>Whenever a <span title="concept-script">script</span> calls into
a <span>plugin</span>, and whenever a <span>plugin</span> calls into
a <span title="concept-script">script</span>, the user agent must
release the <span>storage mutex</span>.</p>
<h5>Processing model</h5>
<p>An <span>event loop</span> must continually run through the
following steps for as long as it exists:</p>
<ol>
<li><p>Run the oldest <span title="concept-task">task</span> on one
of the <span>event loop</span>'s <span title="task queue">task
queues</span>, ignoring tasks whose associated
<code>Document</code>s are not <span>fully active</span>. The user
agent may pick any <span>task queue</span>.</p></li>
<li><p>If the <span>storage mutex</span> is now owned by the
<span>event loop</span>, release it so that it is once again
free.</p>
<li><p>Remove that task from its <span>task queue</span>.</p></li>
<li><p>If any asynchronously-running algorithms are <dfn
title="await a stable state">awaiting a stable state</dfn>, then
run their <dfn>synchronous section</dfn> and then resume running
their asynchronous algorithm.</p>
<p class="note">A <span>synchronous section</span> never mutates
the DOM, runs any script, or has any other side-effects.</p>
<p class="note">Steps in <span title="synchronous
section">synchronous sections</span> are marked with
⌛.</p></li>
<li><p>If necessary, update the rendering or user interface of any
<code>Document</code> or <span>browsing context</span> to reflect
the current state.</p></li>
<li><p>Return to the first step of the <span>event
loop</span>.</p></li>
</ol>
<hr>
<p>When an algorithm says to <dfn>spin the event loop</dfn> until
a condition <var title="">goal</var> is met, the user agent must run
the following steps:</p>
<ol>
<li><p>Let <var title="">task source</var> be the <span>task
source</span> of the currently running <span
title="concept-task">task</span>.</p></li>
<li><p>Stop the currently running <span
title="concept-task">task</span>, allowing the <span>event
loop</span> to resume, but continue these steps
asynchronously.</p></li>
<li><p>Wait until the condition <var title="">goal</var> is
met.</p></li>
<li><p><span>Queue a task</span> to continue running these steps,
using the <span>task source</span> <var title="">task
source</var>. Wait until this task runs before continuing these
steps.</p></li>
<li><p>Return to the caller.</p></li>
</ol>
<hr>
<p>Some of the algorithms in this specification, for historical
reasons, require the user agent to <dfn>pause</dfn> while running a
<span title="concept-task">task</span> until some condition has been
met. While a user agent has a paused <span
title="concept-task">task</span>, the corresponding <span>event
loop</span> must not run further <span
title="concept-task">tasks</span>, and any script in the currently
running <span title="concept-task">task</span> must block. User
agents should remain responsive to user input while paused, however,
albeit in a reduced capacity since the <span>event loop</span> will
not be doing anything.</p>
<hr>
<p>When a user agent is to <dfn>obtain the storage mutex</dfn> as
part of running a <span title="concept-task">task</span>, it must
run through the following steps:</p>
<ol>
<li><p>If the <span>storage mutex</span> is already owned by this
<span title="concept-task">task</span>'s <span>event loop</span>,
then abort these steps.</p></li>
<li><p>Otherwise, <span>pause</span> until the <span>storage
mutex</span> can be taken by the <span>event loop</span>.</p></li>
<li><p>Take ownership of the <span>storage mutex</span>.</p></li>
</ol>
</div>
<div class="impl">
<h5>Generic task sources</h5>
<p>The following <span title="task source">task sources</span> are
used by a number of mostly unrelated features in this and other
specifications.</p>
<dl>
<dt>The <dfn>DOM manipulation task source</dfn></dt>
<dd>
<p>This <span>task source</span> is used for features that react
to DOM manipulations, such as things that happen asynchronously
when an element is <span title="insert an element into a
document">inserted into the document</span>.</p>
<!--
<p>Asynchronous mutation events must be dispatched using <span
title="concept-task">tasks</span> <span title="queue a
task">queued</span> with the <span>DOM manipulation task
source</span>. <a href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
-->
</dd>
<dt>The <dfn>user interaction task source</dfn></dt>
<dd>
<p>This <span>task source</span> is used for features that react
to user interaction, for example keyboard or mouse input.</p>
<p>Asynchronous events sent in response to user input (e.g. <span
title="event-click">click</span> events) must be dispatched using
<span title="concept-task">tasks</span> <span title="queue a
task">queued</span> with the <span>user interaction task
source</span>. <a href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
</dd>
<dt>The <dfn>networking task source</dfn></dt>
<dd>
<p>This <span>task source</span> is used for features that trigger
in response to network activity.</p>
<!-- XHR should use this -->
</dd>
</dl>
</div>
<div class="impl">
<!-- SCRIPT EXEC -->
<h4 id="javascript-protocol"><dfn title="javascript protocol">The <code title="">javascript:</code> protocol</dfn></h4>
<p>When a <span>URL</span> using the <code
title="">javascript:</code> protocol is <dfn
title="concept-js-deref">dereferenced</dfn>, the user agent must run
the following steps:</p>
<ol>
<li><p>Let the script source be the string obtained using the
content retrieval operation defined for <code
title="">javascript:</code> URLs. <a
href="#refsJSURL">[JSURL]</a></p></li>
<li>
<p>Use the appropriate step from the following list:</p>
<dl>
<dt>If a <span>browsing context</span> is being <span
title="navigate">navigated</span> to a <code>javascript:</code>
URL, and the <span>active document</span> of that browsing
context has the <span>same origin</span> as the script given by
that URL</dt>
<dd>
<!-- http://www.hixie.ch/tests/adhoc/html/navigation/javascript-url/ -->
<p>Let <var title="">address</var> be the <span title="the
document's address">address</span> of the <span>active
document</span> of the <span>browsing context</span> being
navigated.</p>
<p>If <var title="">address</var> is <code>about:blank</code>,
and the <span>browsing context</span> being navigated has a
<span>creator browsing context</span>, then let <var
title="">address</var> be the <span title="the document's
address">address</span> of the <span>creator
<code>Document</code></span> instead.</p>
<p><span title="create a script from a node">Create a
script</span> from the <code>Document</code> node of the
<span>active document</span>, using the aforementioned script
source, and assuming the scripting language is JavaScript.</p>
<p>Let <var title="">result</var> be the return value of the
<i>initial code entry-point</i> of this <span
title="concept-script">script</span>. If an exception was
raised, let <var title="">result</var> be void instead. (The
result will be void also if <span
title="concept-bc-noscript">scripting is disabled</span>.)</p>
<p>When it comes time to <span>set the document's address</span>
in the <span title="navigate">navigation algorithm</span>, use
<var title="">address</var> as the <span>override
URL</span>.</p>
</dd>
<dt>If the <code>Document</code> object of the element,
attribute, or style sheet from which the <code>javascript:</code>
URL was reached has an associated <span>browsing
context</span></dt>
<dd>
<p><span>Create an impotent script</span> using the
aforementioned script source, with the scripting language set to
JavaScript, and with the <code>Document</code>'s object's
<span>browsing context</span> as the browsing context.</p>
<p>Let <var title="">result</var> be the return value of the
<i>initial code entry-point</i> of this <span
title="concept-script">script</span>. If an exception was
raised, let <var title="">result</var> be void instead. (The
result will be void also if <span
title="concept-bc-noscript">scripting is disabled</span>.)</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p>Let <var title="">result</var> be void.</p>
</dd>
</dl>
</li>
<li>
<p>If the result of executing the script is void (there is no
return value), then the URL must be treated in a manner equivalent
to an HTTP resource with an HTTP 204 No Content response.</p>
<p>Otherwise, the URL must be treated in a manner equivalent to an
HTTP resource with a 200 OK response whose <span
title="Content-Type">Content-Type metadata</span> is
<code>text/html</code> and whose response body is the return value
converted to a string value.</p>
<p class="note">Certain contexts, in particular <code>img</code>
elements, ignore the <span title="Content-Type">Content-Type
metadata</span>.</p>
</li>
</ol>
<div class="example">
<p>So for example a <code title="">javascript:</code> URL for a
<code title="attr-img-src">src</code> attribute of an
<code>img</code> element would be evaluated in the context of an
empty object as soon as the attribute is set; it would then be
sniffed to determine the image type and decoded as an image.</p>
<p>A <code title="">javascript:</code> URL in an <code
title="attr-hyperlink-href">href</code> attribute of an <code>a</code>
element would only be evaluated when the link was <span
title="following hyperlinks">followed</span>.</p>
<p>The <code title="attr-iframe-src">src</code> attribute of an
<code>iframe</code> element would be evaluated in the context of
the <code>iframe</code>'s own <span>browsing context</span>; once
evaluated, its return value (if it was not void) would replace that
<span>browsing context</span>'s document, thus changing the
variables visible in that <span>browsing context</span>.</p>
</div>
</div>
<h4>Events</h4>
<div class="impl">
<h5 id="event-handler-attributes">Event handlers</h5>
</div>
<!--test: <a href="http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A...%3Cscript%3E%0Aw(a%3Ddocument.implementation.createDocument(null%2C%20null%2C%20null))%3B%0Aw(a.appendChild(a.createElementNS('http%3A%2F%2Fwww.w3.org%2F1999%2Fxhtml'%2C%20'html')))%3B%0Aw(b%3Da.firstChild.appendChild(a.createElementNS('http%3A%2F%2Fwww.w3.org%2F1999%2Fxhtml'%2C%20'body')))%3B%0Aw(b.test%20%3D%20w)%3B%0Aw(b.setAttribute('onclick'%2C%20'test(%22fire%3A%20%22%20%2B%20event)'))%3B%0Aw(b.onclick)%3B%0Aw(e%3Da.createEvent('Event'))%3B%0Aw(e.initEvent('click'%2C%20false%2C%20false))%3B%0Aw(b.dispatchEvent(e))%3B%0A%3C%2Fscript%3E">test</a>-->
<p>Many objects can have <dfn>event handlers</dfn> specified. These
act as bubbling event listeners for the object on which they are
specified.</p>
<p>An <span title="event handlers">event handler</span> can either
have the value null or be set to a <code>Function</code>
object. <span class="impl">Initially, event handlers must be set to
null.</span></p>
<p>Event handlers are exposed in one or two ways.</p>
<p>The first way, common to all event handlers, is as an <span
title="event handler IDL attributes">event handler IDL
attribute</span>.</p>
<p>The second way is as an <span title="event handler content
attributes">event handler content attribute</span>. Event handlers
on <span>HTML elements</span> and some of the event handlers on
<code>Window</code> objects are exposed in this way.</p>
<div class="impl">
<hr>
<p><dfn>Event handler IDL attributes</dfn>, on setting, must set the
corresponding event handler to their new value, and on
getting, must return whatever the current value of the corresponding
event handler is (possibly null).</p>
<p>If an <span title="event handler IDL attributes">event handler
IDL attribute</span> exposes an <span title="event handlers">event
handler</span> of an object that doesn't exist, it must always
return null on getting and must do nothing on setting.</p>
<p class="note">This can happen in particular for <span title="event
handler IDL attributes">event handler IDL attribute</span> on
<code>body</code> elements that do not have corresponding
<code>Window</code> objects.</p>
<p class="note">Certain event handler IDL attributes have additional
requirements, in particular the <code
title="handler-MessagePort-onmessage">onmessage</code> attribute of
<code>MessagePort</code> objects.</p>
<hr>
</div>
<p><dfn>Event handler content attributes</dfn>, when specified, must
contain valid JavaScript code matching the <code
title="">FunctionBody</code> production. <a
href="#refsECMA262">[ECMA262]</a></p>
<div class="impl">
<!-- SCRIPT EXEC -->
<p>When an event handler content attribute is set, if the element is
owned by a <code>Document</code> that is in a <span>browsing
context</span>, and <span title="concept-bc-script">scripting is
enabled</span> for that <span>browsing context</span>, the user
agent must run the following steps to create a <span
title="concept-script">script</span> after setting the content
attribute to its new value:</p>
<ol>
<li><p>Set up a <span>script execution environment</span> for
JavaScript.</p></li>
<li>
<p>Using this script execution environment, interpret the
attribute's new value as the body of an anonymous function, with
the function's arguments set as follows:</p>
<dl class="switch">
<dt>If the attribute is the <code
title="handler-window-onerror">onerror</code> attribute of the
<code>Window</code> object</dt>
<dd>Let the function have three arguments, named <code
title="">event</code>, <code title="">source</code>, and <code
title="">fileno</code>.</dd>
<dt>Otherwise</dt>
<dd>Let the function have a single argument called <code
title="">event</code>.</dd>
</dl>
<p>Link the new function's scope chain from the activation object
of the handler, to the element's object, to the element's
<span>form owner</span>, if it has one, to the element's
<code>Document</code> object, to the <code>Window</code> object of
that <code>Document</code>. Set the function's <code>this</code>
parameter to the <code>Element</code> object representing the
element. Let this function be the only entry in the script's
<span>list of code entry-points</span>.</p>
<p class="note">See ECMA262 Edition 3, sections 10.1.6 and 10.2.3,
for more details on activation objects. <a
href="#refsECMA262">[ECMA262]</a></p>
</li>
<li><p>If the previous steps failed to compile the script, then set
the corresponding <span title="event handlers">event handler</span>
to null and abort these steps.</p></li>
<li><p>Set up the <span>script's global object</span>, the
<span>script's browsing context</span>, the <span>script's URL
character encoding</span>, and the <span>script's base URL</span>
from <span>the script settings determined from the node</span> on
which the attribute is being set.</p></li>
<li><p>Set the corresponding <span title="event handlers">event
handler</span> to the aforementioned function.</p></li>
</ol>
<p>When an event handler content attribute is removed, the user
agent must set the corresponding <span title="event handlers">event
handler</span> to null.</p>
<!--
http://software.hixie.ch/utilities/js/live-dom-viewer/saved/245 onload
http://software.hixie.ch/utilities/js/live-dom-viewer/saved/247 onclick
see http://www.w3.org/Bugs/Public/show_bug.cgi?id=7626#c5 for reasoning
-->
</div>
<p class="note">When an <span title="event handler content
attributes">event handler content attribute</span> is set on an
element owned by a <code>Document</code> that is not in a
<span>browsing context</span>, the corresponding event handler is
not changed.</p>
<!-- v2: we should probably support HTML4's Content-Script-Type header here. -->
<div class="impl">
<hr>
<p>All <span>event handlers</span> on an element, whether
set to null or to a <code>Function</code> object, must be registered
as event listeners on the element, as if the <code
title="dom-EventTarget-addEventListenerNS">addEventListenerNS()</code>
method on the <code>Element</code> object's <code>EventTarget</code>
interface had been invoked when the event handler's
element or object was created, with the event type (<var
title="dom-event-type">type</var> argument) equal to the type
corresponding to the event handler (the <dfn>event handler
event type</dfn>), the namespace (<var
title="dom-event-namespaceURI">namespaceURI</var> argument) set to
null, the listener set to be a target and bubbling phase listener
(<var title="dom-event-useCapture">useCapture</var> argument set to
false), the event group set to the default group (<var
title="dom-event-evtGroup">evtGroup</var> argument set to null), and
the event listener itself (<var
title="dom-event-listener">listener</var> argument) set to do
nothing while the event handler's value is not a
<code>Function</code> object, and set to invoke the <code
title="dom-function-call">call()</code> callback of the
<code>Function</code> object associated with the event handler otherwise.</p>
<p class="note">The <var title="dom-event-listener">listener</var>
argument is emphatically <em>not</em> the <span title="event
handlers">event handler</span> itself.</p>
<p class="note">The interfaces implemented by the event object do
not affect whether an <span title="event handlers">event
handler</span> is used or not.</p>
<p>When an <span title="event handlers">event handler</span>'s
<code>Function</code> object is invoked, its <code
title="dom-function-call">call()</code> callback must be invoked
with one argument, set to the <code>Event</code> object of the event
in question.</p>
<p>The handler's return value must then be processed as follows:</p>
<dl class="switch">
<dt>If the event type is <code class="event-mouseover">mouseover</code></dt>
<dd><p>If the return value is a boolean with the value true, then
the event must be canceled.</p></dd>
<dt>If the event object is a <code>BeforeUnloadEvent</code> object</dt>
<dd><p>If the return value is a string, and the event object's
<code title="dom-BeforeUnloadEvent-returnValue">returnValue</code>
attribute's value is the empty string, then set the <code
title="dom-BeforeUnloadEvent-returnValue">returnValue</code>
attribute's value to the return value.</p></dd>
<dt>Otherwise</dt>
<dd><p>If the return value is a boolean with the value false, then
the event must be canceled.</p></dd>
</dl>
<!-- IE actually uncancels the event if the function returns true -->
<hr>
<p>The <code>Function</code> interface represents a function in the
scripting language being used. It is represented in IDL as
follows:</p>
<pre class="idl">[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>Function</dfn> {
any <span title="dom-function-call">call</span>(in any... arguments);
};</pre>
<p>The <dfn title="dom-function-call"><code>call(...)</code></dfn>
method is the object's callback.</p>
<p class="note">In JavaScript, any <code title="">Function</code>
object implements this interface.</p>
</div>
<div class="impl">
<h5>Event handlers on elements, <code>Document</code> objects, and <code>Window</code> objects</h5>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported by all <span>HTML
elements</span>, as both content attributes and IDL attributes, and
on <code>Document</code> and <code>Window</code> objects, as IDL
attributes.</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-onabort"><code>onabort</code></dfn> <td> <code title="event-abort">abort</code>
<tr><td><dfn title="handler-oncanplay"><code>oncanplay</code></dfn> <td> <code title="event-media-canplay">canplay</code>
<tr><td><dfn title="handler-oncanplaythrough"><code>oncanplaythrough</code></dfn> <td> <code title="event-media-canplaythrough">canplaythrough</code>
<tr><td><dfn title="handler-onchange"><code>onchange</code></dfn> <td> <code title="event-change">change</code> <!-- widely used -->
<tr><td><dfn title="handler-onclick"><code>onclick</code></dfn> <td> <code title="event-click">click</code> <!-- widely used -->
<tr><td><dfn title="handler-oncontextmenu"><code>oncontextmenu</code></dfn> <td> <code title="event-contextmenu">contextmenu</code> <!-- widely used -->
<tr><td><dfn title="handler-ondblclick"><code>ondblclick</code></dfn> <td> <code title="event-dblclick">dblclick</code> <!-- widely used -->
<tr><td><dfn title="handler-ondrag"><code>ondrag</code></dfn> <td> <code title="event-drag">drag</code>
<tr><td><dfn title="handler-ondragend"><code>ondragend</code></dfn> <td> <code title="event-dragend">dragend</code>
<tr><td><dfn title="handler-ondragenter"><code>ondragenter</code></dfn> <td> <code title="event-dragenter">dragenter</code>
<tr><td><dfn title="handler-ondragleave"><code>ondragleave</code></dfn> <td> <code title="event-dragleave">dragleave</code>
<tr><td><dfn title="handler-ondragover"><code>ondragover</code></dfn> <td> <code title="event-dragover">dragover</code>
<tr><td><dfn title="handler-ondragstart"><code>ondragstart</code></dfn> <td> <code title="event-dragstart">dragstart</code> <!-- widely used -->
<tr><td><dfn title="handler-ondrop"><code>ondrop</code></dfn> <td> <code title="event-drop">drop</code>
<tr><td><dfn title="handler-ondurationchange"><code>ondurationchange</code></dfn> <td> <code title="event-media-durationchange">durationchange</code>
<tr><td><dfn title="handler-onemptied"><code>onemptied</code></dfn> <td> <code title="event-media-emptied">emptied</code>
<tr><td><dfn title="handler-onended"><code>onended</code></dfn> <td> <code title="event-media-ended">ended</code>
<tr><td><dfn title="handler-onformchange"><code>onformchange</code></dfn> <td> <code title="event-formchange">formchange</code>
<tr><td><dfn title="handler-onforminput"><code>onforminput</code></dfn> <td> <code title="event-forminput">forminput</code>
<tr><td><dfn title="handler-oninput"><code>oninput</code></dfn> <td> <code title="event-input">input</code>
<tr><td><dfn title="handler-oninvalid"><code>oninvalid</code></dfn> <td> <code title="event-invalid">invalid</code>
<tr><td><dfn title="handler-onkeydown"><code>onkeydown</code></dfn> <td> <code title="event-keydown">keydown</code> <!-- widely used -->
<tr><td><dfn title="handler-onkeypress"><code>onkeypress</code></dfn> <td> <code title="event-keypress">keypress</code> <!-- widely used -->
<tr><td><dfn title="handler-onkeyup"><code>onkeyup</code></dfn> <td> <code title="event-keyup">keyup</code> <!-- widely used -->
<tr><td><dfn title="handler-onloadeddata"><code>onloadeddata</code></dfn> <td> <code title="event-media-loadeddata">loadeddata</code>
<tr><td><dfn title="handler-onloadedmetadata"><code>onloadedmetadata</code></dfn> <td> <code title="event-media-loadedmetadata">loadedmetadata</code>
<tr><td><dfn title="handler-onloadstart"><code>onloadstart</code></dfn> <td> <code title="event-media-loadstart">loadstart</code>
<tr><td><dfn title="handler-onmousedown"><code>onmousedown</code></dfn> <td> <code title="event-mousedown">mousedown</code> <!-- widely used -->
<tr><td><dfn title="handler-onmousemove"><code>onmousemove</code></dfn> <td> <code title="event-mousemove">mousemove</code> <!-- widely used -->
<tr><td><dfn title="handler-onmouseout"><code>onmouseout</code></dfn> <td> <code title="event-mouseout">mouseout</code> <!-- widely used -->
<tr><td><dfn title="handler-onmouseover"><code>onmouseover</code></dfn> <td> <code title="event-mouseover">mouseover</code> <!-- widely used -->
<tr><td><dfn title="handler-onmouseup"><code>onmouseup</code></dfn> <td> <code title="event-mouseup">mouseup</code> <!-- widely used -->
<tr><td><dfn title="handler-onmousewheel"><code>onmousewheel</code></dfn> <td> <code title="event-mousewheel">mousewheel</code> <!-- widely used -->
<tr><td><dfn title="handler-onpause"><code>onpause</code></dfn> <td> <code title="event-media-pause">pause</code>
<tr><td><dfn title="handler-onplay"><code>onplay</code></dfn> <td> <code title="event-media-play">play</code>
<tr><td><dfn title="handler-onplaying"><code>onplaying</code></dfn> <td> <code title="event-media-playing">playing</code>
<tr><td><dfn title="handler-onprogress"><code>onprogress</code></dfn> <td> <code title="event-media-progress">progress</code>
<tr><td><dfn title="handler-onratechange"><code>onratechange</code></dfn> <td> <code title="event-media-ratechange">ratechange</code>
<tr><td><dfn title="handler-onreadystatechange"><code>onreadystatechange</code></dfn> <td> <code title="event-readystatechange">readystatechange</code>
<tr><td><dfn title="handler-onscroll"><code>onscroll</code></dfn> <td> <code title="event-scroll">scroll</code> <!-- widely used --> <!-- [CSSOM] -->
<tr><td><dfn title="handler-onseeked"><code>onseeked</code></dfn> <td> <code title="event-media-seeked">seeked</code>
<tr><td><dfn title="handler-onseeking"><code>onseeking</code></dfn> <td> <code title="event-media-seeking">seeking</code>
<tr><td><dfn title="handler-onselect"><code>onselect</code></dfn> <td> <code title="event-select">select</code> <!-- widely used --> <!-- [CSSOM] -->
<tr><td><dfn title="handler-onshow"><code>onshow</code></dfn> <td> <code title="event-show">show</code>
<tr><td><dfn title="handler-onstalled"><code>onstalled</code></dfn> <td> <code title="event-media-stalled">stalled</code>
<tr><td><dfn title="handler-onsubmit"><code>onsubmit</code></dfn> <td> <code title="event-submit">submit</code> <!-- widely used -->
<tr><td><dfn title="handler-onsuspend"><code>onsuspend</code></dfn> <td> <code title="event-media-suspend">suspend</code>
<tr><td><dfn title="handler-ontimeupdate"><code>ontimeupdate</code></dfn> <td> <code title="event-media-timeupdate">timeupdate</code>
<tr><td><dfn title="handler-onvolumechange"><code>onvolumechange</code></dfn> <td> <code title="event-media-volumechange">volumechange</code>
<tr><td><dfn title="handler-onwaiting"><code>onwaiting</code></dfn> <td> <code title="event-media-waiting">waiting</code>
<!-- not supported, use dnd: -->
<!--<tr><td><dfn title="handler-onbeforecopy"><code>onbeforecopy</code></dfn> <td> <code title="event-beforecopy">beforecopy</code>--> <!-- widely used -->
<!--<tr><td><dfn title="handler-oncopy"><code>oncopy</code></dfn> <td> <code title="event-copy">copy</code>--> <!-- widely used -->
<!--<tr><td><dfn title="handler-onpaste"><code>onpaste</code></dfn> <td> <code title="event-paste">paste</code>--> <!-- widely used -->
<!-- not supported yet (v2?): -->
<!--<tr><td><dfn title="handler-onselectstart"><code>onselectstart</code></dfn> <td> <code title="event-selectstart">selectstart</code>--> <!-- widely used -->
</table>
<hr>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported by all <span>HTML
elements</span> other than <code>body</code>, as both content
attributes and IDL attributes, and on <code>Document</code> objects,
as IDL attributes:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-onblur"><code>onblur</code></dfn> <td> <code title="event-blur">blur</code> <!-- widely used -->
<tr><td><dfn title="handler-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
<tr><td><dfn title="handler-onfocus"><code>onfocus</code></dfn> <td> <code title="event-focus">focus</code> <!-- widely used -->
<tr><td><dfn title="handler-onload"><code>onload</code></dfn> <td> <code title="event-load">load</code>
</table>
<hr>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported by <code>Window</code>
objects, as IDL attributes on the <code>Window</code> object, and
with corresponding content attributes and IDL attributes exposed on
the <code>body</code> and <code>frameset</code> elements:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-window-onafterprint"><code>onafterprint</code></dfn> <td> <code title="event-afterprint">afterprint</code>
<tr><td><dfn title="handler-window-onbeforeprint"><code>onbeforeprint</code></dfn> <td> <code title="event-beforeprint">beforeprint</code>
<tr><td><dfn title="handler-window-onbeforeunload"><code>onbeforeunload</code></dfn> <td> <code title="event-beforeunload">beforeunload</code>
<tr><td><dfn title="handler-window-onblur"><code>onblur</code></dfn> <td> <code title="event-blur">blur</code>
<tr><td><dfn title="handler-window-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
<tr><td><dfn title="handler-window-onfocus"><code>onfocus</code></dfn> <td> <code title="event-focus">focus</code>
<tr><td><dfn title="handler-window-onhashchange"><code>onhashchange</code></dfn> <td> <code title="event-hashchange">hashchange</code> <!-- new -->
<tr><td><dfn title="handler-window-onload"><code>onload</code></dfn> <td> <code title="event-load">load</code> <!-- widely used -->
<tr><td><dfn title="handler-window-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code> <!-- new for postMessage -->
<tr><td><dfn title="handler-window-onoffline"><code>onoffline</code></dfn> <td> <code title="event-offline">offline</code> <!-- new -->
<tr><td><dfn title="handler-window-ononline"><code>ononline</code></dfn> <td> <code title="event-online">online</code> <!-- new -->
<tr><td><dfn title="handler-window-onpagehide"><code>onpagehide</code></dfn> <td> <code title="event-pagehide">pagehide</code> <!-- new -->
<tr><td><dfn title="handler-window-onpageshow"><code>onpageshow</code></dfn> <td> <code title="event-pageshow">pageshow</code> <!-- new -->
<tr><td><dfn title="handler-window-onpopstate"><code>onpopstate</code></dfn> <td> <code title="event-popstate">popstate</code> <!-- new -->
<tr><td><dfn title="handler-window-onredo"><code>onredo</code></dfn> <td> <code title="event-redo">redo</code> <!-- new -->
<tr><td><dfn title="handler-window-onresize"><code>onresize</code></dfn> <td> <code title="event-resize">resize</code> <!-- widely used --> <!-- [CSSOM] -->
<tr><td><dfn title="handler-window-onstorage"><code>onstorage</code></dfn> <td> <code title="event-storage">storage</code> <!-- new -->
<tr><td><dfn title="handler-window-onundo"><code>onundo</code></dfn> <td> <code title="event-undo">undo</code> <!-- new -->
<tr><td><dfn title="handler-window-onunload"><code>onunload</code></dfn> <td> <code title="event-unload">unload</code> <!-- widely used -->
</table>
<p class="note">The <code title="handler-window-onerror">onerror</code>
handler is also used for <a
href="#runtime-script-errors">reporting script errors</a>.</p>
</div>
<div class="impl">
<h5>Event firing</h5>
<p>Certain operations and methods are defined as firing events on
elements. For example, the <code title="dom-click">click()</code>
method on the <code>HTMLElement</code> interface is defined as
firing a <code title="event-click">click</code> event on the
element. <a href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p><dfn title="fire a click event">Firing a <code
title="event-click">click</code> event</dfn> means that a <code
title="event-click">click</code> event, which bubbles and is
cancelable, and which uses the <code>MouseEvent</code> interface,
must be dispatched at the given target. The event object must have
its <code title="">screenX</code>, <code title="">screenY</code>,
<code title="">clientX</code>, <code title="">clientY</code>, and
<code title="">button</code> attributes set to 0, its <code
title="">ctrlKey</code>, <code title="">shiftKey</code>, <code
title="">altKey</code>, and <code title="">metaKey</code> attributes
set according to the current state of the key input device, if any
(false for any keys that are not available), its <code
title="">detail</code> attribute set to 1, and its <code
title="">relatedTarget</code> attribute set to null. The <code
title="">getModifierState()</code> method on the object must return
values appropriately describing the state of the key input device at
the time the event is created.</p>
<p><dfn title="fire a simple event">Firing a simple event named <var
title="">e</var></dfn> means that an event with the name <var
title="">e</var>, which does not bubble (except where otherwise
stated) and is not cancelable (except where otherwise stated), and
which uses the <code>Event</code> interface, must be dispatched at
the given target.</p>
<!--
<p><dfn title="fire a progress event">Firing a progress event named
<var title="">e</var></dfn>, optionally in the context of a
particular instance of the <span title="fetch">fetching
algorithm</span>, means that an event with the name <var
title="">e</var>, which does not bubble (except where otherwise
stated) and is not cancelable (except where otherwise stated), and
which uses the <code>ProgressEvent</code> interface, must be
dispatched at the given target element. If there is a <span
title="fetch">fetching algorithm</span>, and the <span>URL</span>
being <span title="fetch">fetched</span> has the <span>same
origin</span> as the <code>Document</code> of the target element,
then the <code
title="dom-ProgressEvents-lengthComputable">lengthComputable</code>
attribute must be set to true if the <span title="fetch">fetching
algorithm</span>'s subject has a known <span
title="concept-fetch-total">size</span>; the <code
title="dom-ProgressEvents-total">total</code> attribute must be set
to the subject's <span title="concept-fetch-total">size</span> if it
is known and zero otherwise; and the <code
title="dom-ProgressEvents-loaded">loaded</code> attribute must be
set to the <span title="concept-fetch-loaded">number of bytes
downloaded</span>, excluding HTTP headers <span
title="concept-http-equivalent-headers">or
equivalent</span>. Otherwise, the <code
title="dom-ProgressEvents-lengthComputable">lengthComputable</code>
attribute must be set to false, and the <code
title="dom-ProgressEvents-total">total</code> and the <code
title="dom-ProgressEvents-loaded">loaded</code> attributes must be
set to zero. <a href="#r-e-f-sPROGRESS">[PROGRESS]</a></p>
(also fix reference in line above)-->
<p>The default action of these event is to do nothing where where
otherwise stated.</p>
</div>
<div class="impl">
<h5>Events and the <code>Window</code> object</h5>
<p>When an event is dispatched at a DOM node in a
<code>Document</code> in a <span>browsing context</span>, if the
event is not a <code title="event-load">load</code> event, the user
agent must also dispatch the event to the <code>Window</code>, as
follows:</p>
<ol>
<li>In the capture phase, the event must propagate to the
<code>Window</code> object before propagating to any of the nodes,
as if the <code>Window</code> object was the parent of the
<code>Document</code> in the dispatch chain.</li>
<li>In the bubble phase, the event must propagate up to the
<code>Window</code> object at the end of the phase, unless bubbling
has been prevented, again as if the <code>Window</code> object was
the parent of the <code>Document</code> in the dispatch chain.</li>
</ol>
</div>
<div class="impl">
<h5 id="runtime-script-errors">Runtime script errors</h5>
<p><i>This section only applies to user agents that support
scripting in general and JavaScript in particular.</i></p>
<p>Whenever an uncaught runtime script error occurs in one of the
scripts associated with a <code>Document</code>, the user agent must
<span>report the error</span> using the <code
title="handler-window-onerror">onerror</code> <span title="event
handlers">event handler</span> of the <span>script's global
object</span>. If the error is still <i
title="concept-error-nothandled">not handled</i> after this, then
the error should be reported to the user.</p>
<hr>
<p>When the user agent is required to <dfn title="report the
error">report an error</dfn> <var title="">error</var> using the
<span title="event handlers">event handler</span> <var
title="">onerror</var>, it must run these steps, after which the
error is either <dfn
title="concept-error-handled"><i>handled</i></dfn> or <dfn
title="concept-error-nothandled"><i>not handled</i></dfn>:</p>
<dl class="switch">
<dt>If the value of <var title="">onerror</var> is a
<code>Function</code></dt>
<dd>
<p>The function must be invoked with three arguments. The three
arguments passed to the function are all <code>DOMString</code>s;
the first must give the message that the UA is considering
reporting, the second must give the <span>absolute URL</span> of
the resource in which the error occurred, and the third must give
the line number in that resource on which the error occurred.</p>
<p>If the function returns false, then the error is <i
title="concept-error-handled">handled</i>. Otherwise, the error is
<i title="concept-error-nothandled">not handled</i>.</p>
<p>Any uncaught exceptions thrown or errors caused by this
function must be reported to the user immediately after the error
that the function was called for, without using the <span
title="report the error">report an error</span> algorithm
again.</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p>The error is <i title="concept-error-nothandled">not handled</i>.</p>
</dd>
</dl>
</div>
<h3 id="timers">Timers</h3>
<p>The <code title="dom-windowtimers-setTimeout">setTimeout()</code>
and <code title="dom-windowtimers-setInterval">setInterval()</code>
methods allow authors to schedule timer-based callbacks.</p>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <dfn>WindowTimers</dfn> {
long <span title="dom-windowtimers-setTimeout">setTimeout</span>(in any handler, in optional any timeout, in any... args);
void <span title="dom-windowtimers-clearTimeout">clearTimeout</span>(in long handle);
long <span title="dom-windowtimers-setInterval">setInterval</span>(in any handler, in optional any timeout, in any... args);
void <span title="dom-windowtimers-clearInterval">clearInterval</span>(in long handle);
};
<span>Window</span> implements <span>WindowTimers</span>;</pre>
<dl class="domintro">
<dt><var title="">handle</var> = <var title="">window</var> . <code title="dom-windowtimers-setTimeout">setTimeout</code>( <var title="">handler</var> [, <var title="">timeout</var> [, <var title="">arguments</var> ] ] )</dt>
<dd>
<p>Schedules a timeout to run <var title="">handler</var> after
<var title="">timeout</var> milliseconds. Any <var
title="">arguments</var> are passed straight through to the <var
title="">handler</var>.</p>
</dd>
<dt><var title="">handle</var> = <var title="">window</var> . <code title="dom-windowtimers-setTimeout">setTimeout</code>( <var title="">code</var> [, <var title="">timeout</var> ] )</dt>
<dd>
<p>Schedules a timeout to compile and run <var title="">code</var>
after <var title="">timeout</var> milliseconds.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-windowtimers-clearTimeout">clearTimeout</code>( <var title="">handle</var> )</dt>
<dd>
<p>Cancels the timeout set with <code title="dom-windowtimers-setTimeout">setTimeout()</code> identified by <var title="">handle</var>.</p>
</dd>
<dt><var title="">handle</var> = <var title="">window</var> . <code title="dom-windowtimers-setInterval">setInterval</code>( <var title="">handler</var> [, <var title="">timeout</var> [, <var title="">arguments</var> ] ] )</dt>
<dd>
<p>Schedules a timeout to run <var title="">handler</var> every
<var title="">timeout</var> milliseconds. Any <var
title="">arguments</var> are passed straight through to the <var
title="">handler</var>.</p>
</dd>
<dt><var title="">handle</var> = <var title="">window</var> . <code title="dom-windowtimers-setInterval">setInterval</code>( <var title="">code</var> [, <var title="">timeout</var> ] )</dt>
<dd>
<p>Schedules a timeout to compile and run <var title="">code</var>
every <var title="">timeout</var> milliseconds.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-windowtimers-clearInterval">clearInterval</code>( <var title="">handle</var> )</dt>
<dd>
<p>Cancels the timeout set with <code title="dom-windowtimers-setInterval">setInterval()</code> identified by <var title="">handle</var>.</p>
</dd>
</dl>
<p class="note">This API does not guarantee that timers will fire
exactly on schedule. Delays due to CPU load, other tasks, etc, are
to be expected.</p>
<div class="impl">
<p class="note">The <code>WindowTimers</code> interface adds to the
<code>Window</code> interface and the <code>WorkerUtils</code>
interface (part of Web Workers).</p>
<p>Each object that implements the <code>WindowTimers</code>
interface has a <dfn>list of active timeouts</dfn> and a <dfn>list
of active intervals</dfn>. Each entry in these lists is identified
by a number, which must be unique within its list for the lifetime
of the object that implements the <code>WindowTimers</code>
interface.</p>
<hr>
<p>The <dfn
title="dom-windowtimers-setTimeout"><code>setTimeout()</code></dfn>
method must run the following steps:
<ol>
<li><p><span>Get the timed task</span>, and let <var
title="">task</var> be the result.</p></li>
<li><p><span>Get the timeout</span>, and let <var
title="">timeout</var> be the result.</p></li>
<li><p>If the currently running <span
title="concept-task">task</span> is a task that was created by
either the <code
title="dom-windowtimers-setTimeout">setTimeout()</code> method, and
<var title="">timeout</var> is less than 4, then increase <var
title="">timeout</var> to 4.</p></li>
<li><p>Add an entry to the <span>list of active timeouts</span>,
identified by a user-agent-defined integer that is greater than
zero.</p></li>
<li><p>Return the number identifying the newly added entry in the
<span>list of active timeouts</span>, and then continue running
this algorithm asynchronously.</p></li>
<li>
<p>If <var title="">context</var> is a <code>Window</code> object,
wait until the <code>Document</code> associated with <var
title="">context</var> has been <span>fully active</span> for a
further <var title="">timeout</var> milliseconds (not necessarily
consecutively).</p>
<p>Otherwise, if <var title="">context</var> is a
<code>WorkerUtils</code> object, wait until <var
title="">timeout</var> milliseconds have passed with the worker
not suspended (not necessarily consecutively).</p>
<p>Otherwise, act as described in the specification that defines
that the <code>WindowTimers</code> interface is implemented by
some other object.</p>
</li>
<li><p>Wait until any invocations of this algorithm started before
this one whose <var title="">timeout</var> is equal to or less than
this one's have completed.</p></li>
<li><p>If the entry in the <span>list of active timeouts</span>
that was added in the earlier step has been cleared, then abort
this algorithm.</p></li>
<li><p><span title="queue a task">Queue</span> the <var
title="">task</var> <span
title="concept-task">task</span>.</p></li>
</ol>
<p>The <dfn
title="dom-windowtimers-clearTimeout"><code>clearTimeout()</code></dfn>
method must clear the entry identified as <var title="">handle</var>
from the <span>list of active timeouts</span> of the
<code>WindowTimers</code> object on which the method was invoked,
where <var title="">handle</var> is the argument passed to the
method.</p>
<hr>
<p>The <dfn
title="dom-windowtimers-setInterval"><code>setInterval()</code></dfn>
method must run the following steps:
<ol>
<li><p><span>Get the timed task</span>, and let <var
title="">task</var> be the result.</p></li>
<li><p><span>Get the timeout</span>, and let <var
title="">timeout</var> be the result.</p></li>
<li><p>If <var title="">timeout</var> is less than 10, then
increase <var title="">timeout</var> to 10.</p></li> <!-- (but see
note below about IE) -->
<li><p>Add an entry to the <span>list of active intervals</span>,
identified by a user-agent-defined integer that is greater than
zero.</p></li>
<li><p>Return the number identifying the newly added entry in the
<span>list of active intervals</span>, and then continue running
this algorithm asynchronously.</p></li>
<!-- Note: IE doesn't actually run intervals with duration zero, it
aborts roughly here in the algorithm for them. -->
<li>
<p><i>Wait</i>: If <var title="">context</var> is a
<code>Window</code> object, wait until the <code>Document</code>
associated with <var title="">context</var> has been <span>fully
active</span> for a further <var title="">interval</var>
milliseconds (not necessarily consecutively).</p>
<p>Otherwise, if <var title="">context</var> is a
<code>WorkerUtils</code> object, wait until <var
title="">interval</var> milliseconds have passed with the worker
not suspended (not necessarily consecutively).</p>
<p>Otherwise, act as described in the specification that defines
that the <code>WindowTimers</code> interface is implemented by
some other object.</p>
</li>
<li><p>If the entry in the <span>list of active intervals</span>
that was added in the earlier step has been cleared, then abort
this algorithm.</p></li>
<li><p><span title="queue a task">Queue</span> the <var
title="">task</var> <span
title="concept-task">task</span>.</p></li>
<li><p>Return to the step labeled <i>wait</i>.</p></li>
</ol>
<p>The <dfn
title="dom-windowtimers-clearInterval"><code>clearInterval()</code></dfn>
method must clear the entry identified as <var title="">handle</var>
from the <span>list of active intervals</span> of the
<code>WindowTimers</code> object on which the method was invoked,
where <var title="">handle</var> is the argument passed to the
method.</p>
<hr>
<p>When the above methods are to <dfn>get the timed task</dfn>, they
must run the following steps:</p>
<ol>
<li>
<p>If the first argument to the method is an object that has an
internal [[Call]] method, then return a <span
title="concept-task">task</span> that calls that [[Call]] method
with as its arguments the third and subsequent arguments to the
method (if any), and abort these steps.</p>
<p>Otherwise, continue with the remaining steps.</p>
</li>
<li><p>Apply the ToString() conversion operator to the first
argument to the method, and let <var title="">script source</var>
be the result.</p></li>
<li><p>Let <var title="">script language</var> be
JavaScript.</p></li>
<li><p>Let <var title="">context</var> be the object on which the
method is implemented (a <code>Window</code> or
<code>WorkerUtils</code> object).</p></li>
<li>
<p>If <var title="">context</var> is a <code>Window</code> object,
let <var title="">global object</var> be <var
title="">context</var>, let <var title="">browsing context</var>
be the <span>browsing context</span> with which <var
title="">global object</var> is associated, let <var
title="">character encoding</var> be the <span title="document's
character encoding">character encoding</span> of the
<code>Document</code> associated with <var title="">global
object</var> (<a href="#sce-not-copy">this is a reference, not a
copy</a>), and let <var title="">base URL</var> be the <span
title="document base URL">base URL</span> of the
<code>Document</code> associated with <var title="">global
object</var> (<a href="#sbu-not-copy">this is a reference, not a
copy</a>).</p>
<p>Otherwise, if <var title="">context</var> is a
<code>WorkerUtils</code> object, let <var title="">global
object</var>, <var title="">browsing context</var>, <var
title="">character encoding</var>, and <var title="">base
URL</var> be the <span>script's global object</span>,
<span>script's browsing context</span>, <span>script's URL
character encoding</span>, and <span>script's base URL</span>
(respectively) of the <span title="concept-script">script</span>
that the <span>run a worker</span> algorithm created when it
created <var title="">context</var>.</p>
<p>Otherwise, act as described in the specification that defines
that the <code>WindowTimers</code> interface is implemented by
some other object.</p>
</li>
<li><p>Return a <span title="concept-task">task</span> that <span
title="create a script">creates a script</span> using <var
title="">script source</var> as the script source, <var
title="">scripting language</var> as the scripting language, <var
title="">global object</var> as the global object, <var
title="">browsing context</var> as the browsing context, <var
title="">character encoding</var> as the URL character encoding,
and <var title="">base URL</var> as the base URL.</p></li>
</ol>
<p>When the above methods are to <dfn>get the timeout</dfn>, they
must run the following steps:</p>
<ol>
<li><p>Let <var title="">timeout</var> be the second argument to
the method, or zero if the argument was omitted.</p></li>
<li><p>Apply the ToString() conversion operator to <var
title="">timeout</var>, and let <var title="">timeout</var>
be the result.</p></li>
<li><p>Apply the ToNumber() conversion operator to <var
title="">timeout</var>, and let <var title="">timeout</var> be the
result.</p></li>
<li><p>If <var title="">timeout</var> is an Infinity value, a
Not-a-Number (NaN) value, or negative, let <var
title="">timeout</var> be zero.</p></li>
<li><p>Round <var title="">timeout</var> down to the nearest
integer, and let <var title="">timeout</var> be the
result.</p></li>
<li><p>Return <var title="">timeout</var>.</p></li>
</ol>
<hr>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <dfn>timer task
source</dfn>.</p>
</div>
<h3>User prompts</h3>
<!--
v2 ideas:
* in-window modal dialogs
- escape/enter handling
- dragging the window out of the tab
* in-window non-modal palettes
- with a solution for the mobile space
-->
<h4>Simple dialogs</h4>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-alert">alert</code>(<var title="">message</var>)</dt>
<dd>
<p>Displays a modal alert with the given message, and waits for the user to dismiss it.</p>
<p>A call to the <code
title="dom-navigator-yieldForStorageUpdates">navigator.yieldForStorageUpdates()</code>
method is implied when this method is invoked.</p>
</dd>
<dt><var title="">result</var> = <var title="">window</var> . <code title="dom-confirm">confirm</code>(<var title="">message</var>)</dt>
<dd>
<p>Displays a modal OK/Cancel prompt with the given message, waits
for the user to dismiss it, and returns true if the user clicks OK
and false if the user clicks Cancel.</p>
<p>A call to the <code
title="dom-navigator-yieldForStorageUpdates">navigator.yieldForStorageUpdates()</code>
method is implied when this method is invoked.</p>
</dd>
<dt><var title="">result</var> = <var title="">window</var> . <code title="dom-prompt">prompt</code>(<var title="">message</var> [, <var title="">default</var>] )</dt>
<dd>
<p>Displays a modal text field prompt with the given message,
waits for the user to dismiss it, and returns the value that the
user entered. If the user cancels the prompt, then returns null
instead. If the second argument is present, then the given value
is used as a default.</p>
<p>A call to the <code
title="dom-navigator-yieldForStorageUpdates">navigator.yieldForStorageUpdates()</code>
method is implied when this method is invoked.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-alert"><code>alert(<var
title="">message</var>)</code></dfn> method, when invoked, must
release the <span>storage mutex</span> and show the given <var
title="">message</var> to the user. The user agent may make the
method wait for the user to acknowledge the message before
returning; if so, the user agent must <span>pause</span> while the
method is waiting.</p>
<p>The <dfn title="dom-confirm"><code>confirm(<var
title="">message</var>)</code></dfn> method, when invoked, must
release the <span>storage mutex</span> and show the given <var
title="">message</var> to the user, and ask the user to respond with
a positive or negative response. The user agent must then
<span>pause</span> as the method waits for the user's response. If
the user responds positively, the method must return true, and if
the user responds negatively, the method must return false.</p>
<p>The <dfn title="dom-prompt"><code>prompt(<var
title="">message</var>, <var title="">default</var>)</code></dfn>
method, when invoked, must release the <span>storage mutex</span>,
show the given <var title="">message</var> to the user, and ask the
user to either respond with a string value or abort. The user agent
must then <span>pause</span> as the method waits for the user's
response. The second argument is optional. If the second argument
(<var title="">default</var>) is present, then the response must be
defaulted to the value given by <var title="">default</var>. If the
user aborts, then the method must return null; otherwise, the method
must return the string that the user responded with.</p>
</div>
<h4>Printing</h4>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-print">print</code>()</dt>
<dd>
<p>Prompts the user to print the page.</p>
<p>A call to the <code
title="dom-navigator-yieldForStorageUpdates">navigator.yieldForStorageUpdates()</code>
method is implied when this method is invoked.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-print"><code>print()</code></dfn> method,
when invoked, must run the <span>printing steps</span>.</p>
<p>User agents should also run the <span>printing steps</span>
whenever the user asks for the opportunity to <span>obtain a
physical form</span> (e.g. printed copy), or the representation of a
physical form (e.g. PDF copy), of a document.</p>
<p>The <dfn>printing steps</dfn> are as follows:</p>
<ol>
<li>
<p>The user agent may display a message to the user and/or may
abort these steps.</p>
<p class="example">For instance, a kiosk browser could silently
ignore any invocations of the <code
title="dom-print">print()</code> method.</p>
<p class="example">For instance, a browser on a mobile device
could detect that there are no printers in the vicinity and
display a message saying so before continuing to offer a "save to
PDF" option.</p>
</li>
<li>
<p>The user agent must <span>fire a simple event</span> named
<code title="event-beforeprint">beforeprint</code> at the
<code>Window</code> object of the <code>Document</code> that is
being printed, as well as any <span title="nested browsing
context">nested browsing contexts</span> in it.</p>
<p class="example">The <code
title="event-beforeprint">beforeprint</code> event can be used
to annotate the printed copy, for instance adding the time at
which the document was printed.</p>
</li>
<li>
<p>The user agent must release the <span>storage mutex</span>.</p>
</li>
<li>
<p>The user agent should offer the user the opportunity to
<span>obtain a physical form</span> (or the representation of a
physical form) of the document. The user agent may wait for the
user to either accept or decline before returning; if so, the user
agent must <span>pause</span> while the method is waiting. Even if
the user agent doesn't wait at this point, the user agent must use
the state of the relevant documents as they are at this point in
the algorithm if and when it eventually creates the alternate
form.</p>
</li>
<li>
<p>The user agent must <span>fire a simple event</span> named
<code title="event-afterprint">afterprint</code> at the
<code>Window</code> object of the <code>Document</code> that is
being printed, as well as any <span title="nested browsing
context">nested browsing contexts</span> in it.</p>
<p class="example">The <code
title="event-afterprint">afterprint</code> event can be used
to revert annotations added in the earlier event, as well as
showing post-printing UI. For instance, if a page is walking the
user through the steps of applying for a home loan, the script
could automatically advance to the next step after having printed
a form or other.</p>
</li>
</ol>
</div>
<h4>Dialogs implemented using separate documents</h4>
<dl class="domintro">
<dt><var title="">result</var> = <var title="">window</var> . <code title="dom-showModalDialog">showModalDialog</code>(<var title="">url</var> [, <var title="">argument</var>] )</dt>
<dd>
<p>Prompts the user with the given page, waits for that page to
close, and returns the return value.</p>
<p>A call to the <code
title="dom-navigator-yieldForStorageUpdates">navigator.yieldForStorageUpdates()</code>
method is implied when this method is invoked.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-showModalDialog"><code>showModalDialog(<var
title="">url</var>, <var title="">argument</var><!--, <var
title="">features</var>-->)</code></dfn> method, when invoked, must
cause the user agent to run the following steps:</p>
<ol>
<li>
<p><span title="resolve a url">Resolve</span> <var
title="">url</var> relative to the <span>first script</span>'s
<span title="script's base URL">base URL</span>.</p>
<p>If this fails, then throw a <code>SYNTAX_ERR</code> exception
and abort these steps.</p>
</li>
<li>
<p>Release the <span>storage mutex</span>.</p>
</li>
<li>
<p>If the user agent is configured such that this invocation of
<code title="dom-showModalDialog">showModalDialog()</code> is
somehow disabled, then return the empty string and abort these
steps.</p>
<p class="note">User agents are expected to disable this method in
certain cases to avoid user annoyance (e.g. as part of their popup
blocker feature). For instance, a user agent could require that a
site be white-listed before enabling this method, or the user
agent could be configured to only allow one modal dialog at a
time.</p>
</li>
<li>
<p>Let <var title="">the list of background browsing
contexts</var> be a list of all the browsing contexts that:</p>
<ul>
<li>are part of the same <span>unit of related browsing
contexts</span> as the browsing context of the
<code>Window</code> object on which the <code
title="dom-showModalDialog">showModalDialog()</code> method was
called, and that</li>
<li>have an <span>active document</span> whose
<span>origin</span> is the <span title="same origin">same</span>
as the <span>origin</span> of the <span
title="concept-script">script</span> that called the <code
title="dom-showModalDialog">showModalDialog()</code> method at
the time the method was called,</li> <!-- Note that changing
document.domain to talk to another domain doesn't make you able
to block that domain -->
</ul>
<p>...as well as any browsing contexts that are nested inside any
of the browsing contexts matching those conditions.</p>
</li>
<li>
<p>Disable the user interface for all the browsing contexts in
<var title="">the list of background browsing contexts</var>. This
should prevent the user from navigating those browsing contexts,
causing events to be sent to those browsing context, or editing
any content in those browsing contexts. However, it does not
prevent those browsing contexts from receiving events from sources
other than the user, from running scripts, from running
animations, and so forth.</p>
</li>
<li>
<p>Create a new <span>auxiliary browsing context</span>, with the
<span>opener browsing context</span> being the browsing context of
the <code>Window</code> object on which the <code
title="dom-showModalDialog">showModalDialog()</code> method was
called. The new auxiliary browsing context has no name.</p>
<p class="note">This <span>browsing context</span>'s
<code>Document</code>s' <code>Window</code> objects all implement
the <code>WindowModal</code> interface.</p>
</li>
<li>
<p>Let the <span>dialog arguments</span> of the new browsing
context be set to the value of <var title="">argument</var>, or
the 'undefined' value if the argument was omitted.</p>
</li>
<li>
<p>Let the <span>dialog arguments' origin</span> be the
<span>origin</span> of the <span
title="concept-script">script</span> that called the <code
title="dom-showModalDialog">showModalDialog()</code> method.</p>
</li>
<li>
<p><span>Navigate</span> the new <span>browsing context</span> to
the <span>absolute URL</span> that resulted from <span
title="resolve a url">resolving</span> <var title="">url</var>
earlier, with <span>replacement enabled</span>, and with the <span
title="script's browsing context">browsing context</span> of the
<span title="concept-script">script</span> that invoked the method
as the <span>source browsing context</span>.</p>
</li>
<li>
<p><span>Spin the event loop</span> until the new <span>browsing
context</span> is closed. (The user agent must allow the user to
indicate that the <span>browsing context</span> is to be
closed.)</p>
</li>
<li>
<p>Reenable the user interface for all the browsing contexts in
<var title="">the list of background browsing contexts</var>.</p>
</li>
<li>
<p>Return the <span>auxiliary browsing context</span>'s
<span>return value</span>.</p>
</li>
</ol>
<p>The <code>Window</code> objects of <code>Document</code>s hosted
by <span title="browsing context">browsing contexts</span> created
by the above algorithm must all have the <code>WindowModal</code>
interface added to their <code>Window</code> interface:</p>
</div>
<pre class="idl">[Supplemental, NoInterfaceObject] interface <dfn>WindowModal</dfn> {
readonly attribute any <span title="dom-WindowModal-dialogArguments">dialogArguments</span>;
attribute DOMString <span title="dom-WindowModal-returnValue">returnValue</span>;
};
<span>Window</span> implements <span>WindowModal</span>; /* sometimes */</pre>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-WindowModal-dialogArguments">dialogArguments</code></dt>
<dd>
<p>Returns the <var title="">argument</var> argument that was
passed to the <code
title="dom-showModalDialog">showModalDialog()</code> method.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-WindowModal-returnValue">returnValue</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current return value for the window.</p>
<p>Can be set, to change the value that will be returned by the
<code title="dom-showModalDialog">showModalDialog()</code>
method.</p>
</dd>
</dl>
<div class="impl">
<p>Such browsing contexts have associated <dfn>dialog
arguments</dfn>, which are stored along with the <dfn>dialog
arguments' origin</dfn>. These values are set by the <code
title="dom-showModalDialog">showModalDialog()</code> method in the
algorithm above, when the browsing context is created, based on the
arguments provided to the method.</p>
<p>The <dfn
title="dom-WindowModal-dialogArguments"><code>dialogArguments</code></dfn>
IDL attribute, on getting, must check whether its browsing context's
<span>active document</span>'s <span>origin</span> is the <span
title="same origin">same</span> as the <span>dialog arguments'
origin</span>. If it is, then the browsing context's <span>dialog
arguments</span> must be returned unchanged. Otherwise, if the
<span>dialog arguments</span> are an object, then the empty string
must be returned, and if the <span>dialog arguments</span> are not
an object, then the stringification of the <span>dialog
arguments</span> must be returned.
<p>These browsing contexts also have an associated <dfn>return
value</dfn>. The <span>return value</span> of a browsing context
must be initialized to the empty string when the browsing context is
created.</p>
<p>The <dfn
title="dom-WindowModal-returnValue"><code>returnValue</code></dfn>
IDL attribute, on getting, must return the <span>return value</span>
of its browsing context, and on setting, must set the <span>return
value</span> to the given new value.</p>
</div>
<p class="note">The <code
title="dom-window-close">window.close()</code> method can be used to
close the browsing context.</p>
<h3>System state and capabilities</h3>
<div class="impl">
<p>The <dfn title="dom-navigator"><code>navigator</code></dfn>
attribute of the <code>Window</code> interface must return an
instance of the <code>Navigator</code> interface, which represents
the identity and state of the user agent (the client), and allows
Web pages to register themselves as potential protocol and content
handlers:</p>
</div>
<pre class="idl">interface <dfn>Navigator</dfn> {
// objects implementing this interface also implement the interfaces given below
};
<span>Navigator</span> implements <span>NavigatorID</span>;
<span>Navigator</span> implements <span>NavigatorOnLine</span>;
<span>Navigator</span> implements <span>NavigatorAbilities</span>;
[Supplemental, NoInterfaceObject]
interface <dfn>NavigatorID</dfn> {<!--
readonly attribute DOMString <span title="dom-navigator-appCodeName">appCodeName</span>;-->
readonly attribute DOMString <span title="dom-navigator-appName">appName</span>;
readonly attribute DOMString <span title="dom-navigator-appVersion">appVersion</span>;
readonly attribute DOMString <span title="dom-navigator-platform">platform</span>;
readonly attribute DOMString <span title="dom-navigator-userAgent">userAgent</span>;
};
[Supplemental, NoInterfaceObject]
interface <dfn>NavigatorOnLine</dfn> {
readonly attribute boolean <span title="dom-navigator-onLine">onLine</span>;
};
[Supplemental, NoInterfaceObject]
interface <dfn>NavigatorAbilities</dfn> {
// content handler registration
void <span title="dom-navigator-registerProtocolHandler">registerProtocolHandler</span>(in DOMString scheme, in DOMString url, in DOMString title);
void <span title="dom-navigator-registerContentHandler">registerContentHandler</span>(in DOMString mimeType, in DOMString url, in DOMString title);
void <span title="dom-navigator-yieldForStorageUpdates">yieldForStorageUpdates</span>();
<!-- v2: cookieEnabled geolocator javaEnabled mozIsLocallyAvailable preference
readonly attribute <span>MimeTypeArray</span> <span title="dom-navigator-mimeTypes">mimeTypes</span>;
readonly attribute <span>PluginArray</span> <span title="dom-navigator-plugins">plugins</span>;
(the latter is used in a <video> element demo now, so we might need to pull this forward from v2!)
-->};</pre>
<div class="impl">
<p>These interfaces are defined separately so that other
specifications can re-use parts of the <code>Navigator</code>
interface.</p>
<!-- v2: also, see window.external.AddSearchProvider() and similar DOM APIs from IE -->
<!-- v2: also, could expose languages:
<dt><dfn title="dom-navigator-browserLanguage"><code>browserLanguage</code></dfn></dt> <!- - Opera and IE only - ->
<dd><p>Must return either null or a language code representing the language the browser uses in its interface.</p></dd>
<dt><dfn title="dom-navigator-userLanguage"><code>userLanguage</code></dfn></dt> <!- - Opera and IE only - ->
<dt><dfn title="dom-navigator-language"><code>language</code></dfn></dt> <!- - Opera, Safari, and Mozilla only - ->
<dd><p>Must return either null or a language code representing the user's preferred language.</p></dd>
-->
</div>
<h4>Client identification</h4>
<p>In certain cases, despite the best efforts of the entire
industry, Web browsers have bugs and limitations that Web authors
are forced to work around.</p>
<p>This section defines a collection of attributes that can be used
to determine, from script, the kind of user agent in use, in order
to work around these issues.</p>
<p>Client detection should always be limited to detecting known
current versions; future versions and unknown versions should always
be assumed to be fully compliant.</p>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-navigator">navigator</code> . <code title="dom-navigator-appName">appName</code></dt>
<dd>
<p>Returns the name of the browser.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-navigator">navigator</code> . <code title="dom-navigator-appVersion">appVersion</code></dt>
<dd>
<p>Returns the version of the browser.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-navigator">navigator</code> . <code title="dom-navigator-platform">platform</code></dt>
<dd>
<p>Returns the name of the platform.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-navigator">navigator</code> . <code title="dom-navigator-userAgent">userAgent</code></dt>
<dd>
<p>Returns the complete User-Agent header.</p>
</dd>
</dl>
<div class="impl">
<dl>
<!-- redundant
<dt><dfn title="dom-navigator-appCodeName"><code>appCodeName</code></dfn></dt>
<dd><p>Must return the string "<code title="">Mozilla</code>".</p></dd>
-->
<!-- appMinorVersion: IE only. In IE8b1, returns " Beta" (with the space) -->
<dt><dfn title="dom-navigator-appName"><code>appName</code></dfn></dt>
<dd><p>Must return either the string "<code title="">Netscape</code>" or the full name of the browser, e.g. "<code title="">Mellblom Browsernator</code>".</p></dd>
<dt><dfn title="dom-navigator-appVersion"><code>appVersion</code></dfn></dt>
<dd><p>Must return either the string "<code title="">4.0</code>" or a string representing the version of the browser in detail, e.g. "<code title="">1.0 (VMS; en-US) Mellblomenator/9000</code>".</p></dd>
<!-- buildID: Mozilla only -->
<!-- oscpu: Mozilla only -->
<dt><dfn title="dom-navigator-platform"><code>platform</code></dfn></dt>
<dd><p>Must return either the empty string or a string representing the platform on which the browser is executing, e.g. "<code title="">MacIntel</code>", "<code title="">Win32</code>", "<code title="">FreeBSD i386</code>", "<code title="">WebTV OS</code>".</p></dd>
<!-- product: Mozilla and Safari only; always returns "Gecko" -->
<!-- productSub: Mozilla and Safari only; returns same as buildID in Mozilla, and returns the fixed string "20030107" in Safari -->
<!-- securityPolicy: Mozilla only; always returns "" -->
<!-- taintEnabled(): Opera, IE and Mozilla have this function as one that always returns false -->
<dt><dfn title="dom-navigator-userAgent"><code>userAgent</code></dfn></dt>
<dd><p>Must return the string used for the value of the "<code title="">User-Agent</code>" header in HTTP requests, or the empty string if no such header is ever sent.</p></dd>
<!-- vendor: Mozilla and Safari only; always returns "" in Mozilla, and returns the fixed string "Apple Computer, Inc." in Safari -->
<!-- vendorSub: Mozilla and Safari only; always returns "" -->
</dl>
</div>
<h4 id="custom-handlers">Custom scheme and content handlers</h4>
<p>The <dfn
title="dom-navigator-registerProtocolHandler"><code>registerProtocolHandler()</code></dfn>
method allows Web sites to register themselves as possible handlers
for particular schemes. For example, an online fax service could
register itself as a handler of the <code>fax:</code> scheme (<a
href="#refsRFC2806">[RFC2806]</a>), so that if the user clicks on
such a link, he is given the opportunity to use that Web
site. Analogously, the <dfn
title="dom-navigator-registerContentHandler"><code>registerContentHandler()</code></dfn>
method allows Web sites to register themselves as possible handlers
for content in a particular <span>MIME type</span>. For example, the same online
fax service could register itself as a handler for
<code>image/g3fax</code> files (<a
href="#refsRFC1494">[RFC1494]</a>), so that if the user has no
native application capable of handling G3 Facsimile byte streams,
his Web browser can instead suggest he use that site to view the
image.</p>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-navigator">navigator</code> . <code title="dom-navigator-registerProtocolHandler">registerProtocolHandler</code>(<var title="">scheme</var>, <var title="">url</var>, <var title="">title</var>)</dt>
<dt><var title="">window</var> . <code title="dom-navigator">navigator</code> . <code title="dom-navigator-registerContentHandler">registerContentHandler</code>(<var title="">mimeType</var>, <var title="">url</var>, <var title="">title</var>)</dt>
<dd>
<p>Registers a handler for the given scheme or content type, at
the given URL, with the given title.</p>
<p>The string "<code title="">%s</code>" in the URL is used as a
placeholder for where to put the URL of the content to be
handled.</p>
<p>Throws a <code>SECURITY_ERR</code> exception if the user agent
blocks the registration (this might happen if trying to register
as a handler for "http", for instance).</p>
<p>Throws a <code>SYNTAX_ERR</code> if the "<code
title="">%s</code>" string is missing in the URL.</p>
</dd>
</dl>
<div class="impl">
<p>User agents may, within the constraints described in this
section, do whatever they like when the methods are called. A UA
could, for instance, prompt the user and offer the user the
opportunity to add the site to a shortlist of handlers, or make the
handlers his default, or cancel the request. UAs could provide such
a UI through modal UI or through a non-modal transient notification
interface. UAs could also simply silently collect the information,
providing it only when relevant to the user.</p>
<p>User agents should keep track of which sites have registered
handlers (even if the user has declined such registrations) so that
the user is not repeatedly prompted with the same request.</p>
<p>The arguments to the methods have the following meanings and
corresponding implementation requirements:</p>
<dl>
<dt><var title="">protocol</var> (<code title="dom-navigator-registerProtocolHandler">registerProtocolHandler()</code> only)</dt>
<dd>
<p>A scheme, such as <code>ftp</code> or <code>fax</code>. The
scheme must be compared in an <span>ASCII case-insensitive</span>
manner by user agents for the purposes of comparing with the
scheme part of URLs that they consider against the list of
registered handlers.</p>
<p>The <var title="">scheme</var> value, if it contains a colon
(as in "<code>ftp:</code>"), will never match anything, since
schemes don't contain colons.</p>
<p class="note">This feature is not intended to be used with
non-standard protocols.</p>
</dd>
<dt><var title="">mimeType</var> (<code title="dom-navigator-registerContentHandler">registerContentHandler()</code> only)</dt>
<dd>
<p>A <span>MIME type</span>, such as <code>model/vrml</code> or
<code>text/richtext</code>. The <span>MIME type</span> must be
compared in an <span>ASCII case-insensitive</span> manner by user
agents for the purposes of comparing with MIME types of documents
that they consider against the list of registered handlers.</p>
<p>User agents must compare the given values only to the MIME
type/subtype parts of content types, not to the complete type
including parameters. Thus, if <var title="">mimeType</var> values
passed to this method include characters such as commas or
whitespace, or include MIME parameters, then the handler being
registered will never be used.</p>
<p class="note">The type is compared to the <span>MIME type</span> used by the
user agent <em>after</em> the sniffing algorithms have been
applied.</p>
</dd>
<dt><var title="">url</var></dt>
<dd>
<p>The <span>URL</span> of the page that will handle the
requests.</p>
<p>When the user agent uses this URL, it must replace the first
occurrence of the exact literal string "<code title="">%s</code>"
with an escaped version of the <span>absolute URL</span> of the
content in question (as defined below), then <span title="resolve
a url">resolve</span> the resulting URL, relative to the <span
title="script's base URL">base URL</span> of the <span>first
script</span> at the time the <code
title="dom-navigator-registerContentHandler">registerContentHandler()</code>
or <code
title="dom-navigator-registerProtocolHandler">registerProtocolHandler()</code>
methods were invoked, and then <span>navigate</span> an
appropriate <span>browsing context</span> to the resulting URL
using the GET method (<span title="concept-http-equivalent-get">or
equivalent</span> for non-HTTP URLs).</p>
<p>To get the escaped version of the <span>absolute URL</span> of
the content in question, the user agent must replace every
character in that <span>absolute URL</span> that doesn't match the
<query> production defined in RFC 3986 by the
percent-encoded form of that character. <a
href="#refsRFC3986">[RFC3986]</a></p>
<div class="example">
<p>If the user had visited a site at <code
title="">http://example.com/</code> that made the following
call:</p>
<pre>navigator.registerContentHandler('application/x-soup', 'soup?url=%s', 'SoupWeb™')</pre>
<p>...and then, much later, while visiting <code
title="">http://www.example.net/</code>, clicked on a link such
as:</p>
<pre><a href="chickenkïwi.soup">Download our Chicken Kïwi soup!</a></pre>
<p>...then, assuming this <code>chickenkïwi.soup</code> file
was served with the <span>MIME type</span> <code>application/x-soup</code>,
the UA might navigate to the following URL:</p>
<pre>http://example.com/soup?url=http://www.example.net/chickenk%C3%AFwi.soup</pre>
<p>This site could then fetch the <code>chickenkïwi.soup</code>
file and do whatever it is that it does with soup (synthesize it
and ship it to the user, or whatever).</p>
</div>
</dd>
<dt><var title="">title</var></dt>
<dd>
<p>A descriptive title of the handler, which the UA might use to
remind the user what the site in question is.</p>
</dd>
</dl>
<p>User agents should raise <code>SECURITY_ERR</code> exceptions if
the methods are called with <var title="">scheme</var> or <var
title="">mimeType</var> values that the UA deems to be
"privileged". For example, a site attempting to register a handler
for <code>http</code> URLs or <code>text/html</code> content in a
Web browser would likely cause an exception to be raised.</p>
<p>User agents must raise a <code>SYNTAX_ERR</code> exception if the
<var title="">url</var> argument passed to one of these methods does
not contain the exact literal string "<code>%s</code>", or if <span
title="resolve a url">resolving</span> the <var title="">url</var>
argument with the first occurrence of the string "<code
title="">%s</code>" removed, relative to the <span>first
script</span>'s <span title="script's base URL">base URL</span>, is
not successful.</p>
<p>User agents must not raise any other exceptions (other than
binding-specific exceptions, such as for an incorrect number of
arguments in an JavaScript implementation).</p>
<p>This section does not define how the pages registered by these
methods are used, beyond the requirements on how to process the <var
title="">url</var> value (see above). To some extent, the <span
title="navigate">processing model for navigating across
documents</span> defines some cases where these methods are
relevant, but in general UAs may use this information wherever they
would otherwise consider handing content to native plugins or helper
applications.</p>
<p>UAs must not use registered content handlers to handle content
that was returned as part of a non-GET transaction (or rather, as
part of any non-idempotent transaction), as the remote site would
not be able to fetch the same data.</p>
</div>
<div class="impl">
<h5>Security and privacy</h5>
<p>These mechanisms can introduce a number of concerns, in
particular privacy concerns.</p>
<p><strong>Hijacking all Web usage.</strong> User agents should not
allow schemes that are key to its normal operation, such as
<code>http</code> or <code>https</code>, to be rerouted through
third-party sites. This would allow a user's activities to be
trivially tracked, and would allow user information, even in secure
connections, to be collected.</p>
<p><strong>Hijacking defaults.</strong> It is strongly recommended
that user agents do not automatically change any defaults, as this
could lead the user to send data to remote hosts that the user is
not expecting. New handlers registering themselves should never
automatically cause those sites to be used.</p>
<p><strong>Registration spamming.</strong> User agents should
consider the possibility that a site will attempt to register a
large number of handlers, possibly from multiple domains (e.g. by
redirecting through a series of pages each on a different domain,
and each registering a handler for <code>video/mpeg</code> —
analogous practices abusing other Web browser features have been
used by pornography Web sites for many years). User agents should
gracefully handle such hostile attempts, protecting the user.</p>
<p><strong>Misleading titles.</strong> User agents should not rely
wholly on the <var title="">title</var> argument to the methods when
presenting the registered handlers to the user, since sites could
easily lie. For example, a site <code>hostile.example.net</code>
could claim that it was registering the "Cuddly Bear Happy Content
Handler". User agents should therefore use the handler's domain in
any UI along with any title.</p>
<p><strong>Hostile handler metadata.</strong> User agents should
protect against typical attacks against strings embedded in their
interface, for example ensuring that markup or escape characters in
such strings are not executed, that null bytes are properly handled,
that over-long strings do not cause crashes or buffer overruns, and
so forth.</p>
<p><strong>Leaking Intranet URLs.</strong> The mechanism described
in this section can result in secret Intranet URLs being leaked, in
the following manner:</p>
<ol>
<li>The user registers a third-party content handler as the default
handler for a content type.</li>
<li>The user then browses his corporate Intranet site and accesses
a document that uses that content type.</li>
<li>The user agent contacts the third party and hands the third
party the URL to the Intranet content.</li>
</ol>
<p>No actual confidential file data is leaked in this manner, but
the URLs themselves could contain confidential information. For
example, the URL could be
<code>http://www.corp.example.com/upcoming-aquisitions/the-sample-company.egf</code>,
which might tell the third party that Example Corporation is
intending to merge with The Sample Company. Implementors might wish
to consider allowing administrators to disable this feature for
certain subdomains, content types, or schemes.</p>
<p><strong>Leaking secure URLs.</strong> User agents should not send
HTTPS URLs to third-party sites registered as content handlers, in
the same way that user agents do not send <code
title="http-referer">Referer</code> (sic) HTTP headers from secure
sites to third-party sites.</p>
<p><strong>Leaking credentials.</strong> User agents must never send
username or password information in the URLs that are escaped and
included sent to the handler sites. User agents may even avoid
attempting to pass to Web-based handlers the URLs of resources
that are known to require authentication to access, as such sites
would be unable to access the resources in question without
prompting the user for credentials themselves (a practice that would
require the user to know whether to trust the third-party handler, a
decision many users are unable to make or even understand).</p>
</div>
<div class="impl">
<h5 id="sample-handler-impl">Sample user interface</h5>
<p><i>This section is non-normative.</i></p>
<p>A simple implementation of this feature for a desktop Web browser
might work as follows.</p>
<p>The <code
title="dom-navigator-registerContentHandler">registerContentHandler()</code>
method could display a modal dialog box:</p>
<pre>||[ Content Handler Registration ]||||||||||||||||||||||||||||
| |
| This Web page: |
| |
| Kittens at work |
| http://kittens.example.org/ |
| |
| ...would like permission to handle files of type: |
| |
| application/x-meowmeow |
| |
| using the following Web-based application: |
| |
| Kittens-at-work displayer |
| http://kittens.example.org/?show=%s |
| |
| Do you trust the administrators of the "kittens.example. |
| org" domain? |
| |
| ( Trust kittens.example.org ) (( Cancel )) |
|____________________________________________________________|</pre>
<p>...where "Kittens at work" is the title of the page that invoked
the method, "http://kittens.example.org/" is the URL of that page,
"application/x-meowmeow" is the string that was passed to the <code
title="dom-navigator-registerContentHandler">registerContentHandler()</code>
method as its first argument (<var title="">mimeType</var>),
"http://kittens.example.org/?show=%s" was the second argument (<var
title="">url</var>), and "Kittens-at-work displayer" was the third
argument (<var title="">title</var>).</p>
<p>If the user clicks the Cancel button, then nothing further
happens. If the user clicks the "Trust" button, then the handler is
remembered.</p>
<p>When the user then attempts to fetch a URL that uses the
"application/x-meowmeow" <span>MIME type</span>, then it might display a dialog
as follows:</p>
<pre>||[ Unknown File Type ]|||||||||||||||||||||||||||||||||||||||
| |
| You have attempted to access: |
| |
| data:application/x-meowmeow;base64,S2l0dGVucyBhcmUgd |
| GhlIGN1dGVzdCE%3D |
| |
| How would you like FerretBrowser to handle this resource? |
| |
| (o) Contact the FerretBrowser plugin registry to see if |
| there is an official way to handle this resource. |
| |
| ( ) Pass this URL to a local application: |
| [ /no application selected/ ] ( Choose ) |
| |
| ( ) Pass this URL to the "Kittens-at-work displayer" |
| application at "kittens.example.org". |
| |
| [ ] Always do this for resources using the "application/ |
| x-meowmeow" type in future. |
| |
| ( Ok ) (( Cancel )) |
|____________________________________________________________|</pre>
<p>...where the third option is the one that was primed by the site
registering itself earlier.</p>
<p>If the user does select that option, then the browser, in
accordance with the requirements described in the previous two
sections, will redirect the user to
"http://kittens.example.org/?show=data%3Aapplication/x-meowmeow;base64,S2l0dGVucyBhcmUgdGhlIGN1dGVzdCE%253D".</p>
<p>The <code
title="dom-navigator-registerProtocolHandler">registerProtocolHandler()</code>
method would work equivalently, but for schemes instead of unknown
content types.</p>
</div>
<h4>Manually releasing the storage mutex</h4>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-navigator">navigator</code> . <code title="dom-navigator-yieldForStorageUpdates">yieldForStorageUpdates</code>()</dt>
<dd>
<p>If a script uses the <code
title="dom-document-cookie">document.cookie</code> API, or the
<code title="dom-localStorage">localStorage</code> API, the
browser will block other scripts from accessing cookies or storage
until the first script finishes.</p>
<p>Calling the <code
title="dom-navigator-yieldForStorageUpdates">navigator.yieldForStorageUpdates()</code>
method tells the user agent to unblock any other scripts that may
be blocked, even though the script hasn't returned.</p>
<p>Values of cookies and items in the <code>Storage</code> objects
of <code title="dom-localStorage">localStorage</code> attributes
can change after calling this method, whence its name.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-navigator-yieldForStorageUpdates"><code>yieldForStorageUpdates()</code></dfn>
method, when invoked, must, if the <span>storage mutex</span> is
owned by the <span>event loop</span> of the <span
title="concept-task">task</span> that resulted in the method being
called, release the <span>storage mutex</span> so that it is once
again free. Otherwise, it must do nothing.</p>
</div>
<h3 id="offline">Offline Web applications</h3>
<!-- v2 ideas for appcache:
* A way to limit what gets download when the user agent is
updating the application cache and it turns out the server has
changed EVERY page because every page has a dynamic "site last
modified" date on it.
http://groups.google.com/group/gears-users/browse_thread/thread/efbd808325df607a/c73adb34f9b63cf7?hl=en&q=whatwg#c73adb34f9b63cf7
* Multiuser appcaches.
If the application code (HTML, JS, CSS) is all the same for two
users, then appcache works for multiple users by just having
the data for the users separate from the logic.
This is the expected model for most apps. For example, your
typical blog has just one set of CSS for all users.
For systems where the user affects what HTML, JS, and CSS is
served back, the spec as written pretty much requires that
there be one app per user, and one generic "login" app that
then redirects to one of those other apps - and where each app
has a different base URL, separate manifest, etc.
An alternative that we could explore in a future version is to
have the manifest include a manifest name, and then have script
that allows you to "activate" a particular manifest name for a
given appcache.
So each appcache group would be futher subdivided into named
subgroups, and for a given manifest URL with such a group of
subgroups, one subgroup would be the default one at a time. The
inactive ones would just lie dormant, but and the active ones
would act like now, but there'd be a scripted way to change the
default (and maybe query what available variants exist for the
current appcache), so that you could log back in as someone
else by just making the script pick the other user's variant,
and then reloading.
-->
<h4>Introduction</h4>
<p><i>This section is non-normative.</i></p>
<p>In order to enable users to continue interacting with Web
applications and documents even when their network connection is
unavailable — for instance, because they are traveling outside
of their ISP's coverage area — authors can provide a manifest
which lists the files that are needed for the Web application to
work offline and which causes the user's browser to keep a copy of
the files for use offline.</p>
<p>To illustrate this, consider a simple clock applet consisting of
an HTML page "<code title="">clock.html</code>", a CSS style sheet
"<code title="">clock.css</code>", and a JavaScript script "<code
title="">clock.js</code>".</p>
<p>Before adding the manifest, these three files might look like
this:</p>
<pre>EXAMPLE offline/clock/clock1.html</pre>
<pre>EXAMPLE offline/clock/clock1.css</pre>
<pre>EXAMPLE offline/clock/clock1.js</pre>
<p>If the user tries to open the "<code title="">clock.html</code>"
page while offline, though, the user agent (unless it happens to
have it still in the local cache) will fail with an error.</p>
<p>The author can instead provide a manifest of the three files:</p>
<pre>EXAMPLE offline/clock/clock2.manifest</pre>
<p>With a small change to the HTML file, the manifest (served as
<code>text/cache-manifest</code>) is linked to the application:</p>
<pre>EXAMPLE offline/clock/clock2.html</pre>
<p>Now, if the user goes to the page, the browser will cache the
files and make them available even when the user is offline.</p>
<p class="note">Authors are encouraged to include the main page in
the manifest also, but in practice the page that referenced the
manifest is automatically cached even if it isn't explicitly
mentioned.</p>
<h5 id="appcacheevents">Event summary</h5>
<p><i>This section is non-normative.</i></p>
<p>When the user visits a page that declares a manifest, the browser
will try to update the cache. It does this by fetching a copy of the
manifest and, if the manifest has changed since the user agent last
saw it, redownloading all the resources it mentions and caching them
anew.</p>
<p>As this is going on, a number of events get fired to keep the
script updated as to the state of the cache update, so that the user
can be notified appropriately. The events are as follows:</p>
<table>
<thead>
<tr>
<th> Event name
<th> Interface
<th> Dispatched when...
<th> Next events
<tbody>
<tr>
<td> <dfn title="event-appcache-checking"><code>checking</code></dfn>
<td> <code>Event</code>
<td> The user agent is checking for an update, or attempting to download the manifest for the first time.
<td> <code title="event-appcache-noupdate">noupdate</code>, <code title="event-appcache-downloading">downloading</code>, <code title="event-appcache-obsolete">obsolete</code>, <code title="event-appcache-error">error</code>
<tr>
<td> <dfn title="event-appcache-noupdate"><code>noupdate</code></dfn>
<td> <code>Event</code>
<td> The manifest hadn't changed.
<td> (Last event in sequence.)
<tr>
<td> <dfn title="event-appcache-downloading"><code>downloading</code></dfn>
<td> <code>Event</code>
<td> The user agent has found an update and is fetching it, or is downloading the resources listed by the manifest for the first time.
<td> <code title="event-appcache-progress">progress</code>, <code title="event-appcache-error">error</code>, <code title="event-appcache-cached">cached</code>, <code title="event-appcache-updateready">updateready</code>
<tr>
<td> <dfn title="event-appcache-progress"><code>progress</code></dfn>
<td> <code>ProgressEvent</code>
<td> The user agent is downloading resources listed by the manifest.
<td> <code title="event-appcache-progress">progress</code>, <code title="event-appcache-error">error</code>, <code title="event-appcache-cached">cached</code>, <code title="event-appcache-updateready">updateready</code>
<tr>
<td> <dfn title="event-appcache-cached"><code>cached</code></dfn>
<td> <code>Event</code>
<td> The resources listed in the manifest have been downloaded, and the application is now cached.
<td> Last event in sequence.
<tr>
<td> <dfn title="event-appcache-updateready"><code>updateready</code></dfn>
<td> <code>Event</code>
<td> The resources listed in the manifest have been newly redownloaded, and the script can use <code title="dom-appcache-swapCache">swapCache()</code> to switch to the new cache.
<td> Last event in sequence.
<tr>
<td> <dfn title="event-appcache-obsolete"><code>obsolete</code></dfn>
<td> <code>Event</code>
<td> The manifest was found to have become a 404 or 410 page, so the application cache is being deleted.
<td> Last event in sequence.
<tr>
<td rowspan=4> <dfn title="event-appcache-error"><code>error</code></dfn>
<td rowspan=4> <code>Event</code>
<td> The manifest was a 404 or 410 page, so the attempt to cache the application has been aborted.
<td rowspan=3> Last event in sequence.
<tr>
<td> The manifest hadn't changed, but the page referencing the manifest failed to download properly.
<tr>
<td> A fatal error occurred while fetching the resources listed in the manifest.
<tr>
<td> The manifest changed while the update was being run.
<td> The user agent will try fetching the files again momentarily.
</table>
<div class="impl">
<h4 id="appcache">Application caches</h4>
<p>An <dfn>application cache</dfn> is a set of cached resources
consisting of:</p>
<ul>
<li>
<p>One or more resources (including their out-of-band metadata,
such as HTTP headers, if any), identified by URLs, each falling
into one (or more) of the following categories:</p>
<dl>
<dt><dfn title="concept-appcache-master">Master entries</dfn>
<dd>Documents that were added to the cache because a
<span>browsing context</span> was <span
title="navigate">navigated</span> to that document and the
document indicated that this was its cache, using the <code
title="attr-html-manifest">manifest</code> attribute.
<dt><dfn title="concept-appcache-manifest">The manifest</dfn>
<dd>The resource corresponding to the URL that was given in a
master entry's <code>html</code> element's <code
title="attr-html-manifest">manifest</code> attribute. The
manifest is fetched and processed during the <span>application
cache download process</span>. All the <span
title="concept-appcache-master">master entries</span> have
the <span title="same origin">same origin</span> as the manifest.
<dt><dfn title="concept-appcache-explicit">Explicit entries</dfn>
<dd>Resources that were listed in the cache's <span
title="concept-appcache-manifest">manifest</span> in an <span
title="concept-appcache-manifest-explicit">explicit
section</span>. Explicit entries can also be marked as <dfn
title="concept-appcache-foreign">foreign</dfn>, which means that
they have a <code title="attr-html-manifest">manifest</code>
attribute but that it doesn't point at this cache's <span
title="concept-appcache-manifest">manifest</span>.
<dt><dfn title="concept-appcache-fallback">Fallback entries</dfn>
<dd>Resources that were listed in the cache's <span
title="concept-appcache-manifest">manifest</span> in a <span
title="concept-appcache-manifest-fallback">fallback
section</span>.
</dl>
<p class="note">A URL in the list can be flagged with multiple
different types, and thus an entry can end up being categorized as
multiple entries. For example, an entry can be a manifest entry
and an explicit entry at the same time, if the manifest is listed
within the manifest.</p>
</li>
<li>Zero or more <dfn title="concept-appcache-fallback-ns">fallback
namespaces</dfn>: URLs, used as <span
title="concept-appcache-matches-fallback">prefix match
patterns</span>, each of which is mapped to a <span
title="concept-appcache-fallback">fallback entry</span>. Each
namespace URL has the <span>same origin</span> as <span
title="concept-appcache-manifest">the manifest</span>.</li>
<li>Zero or more URLs that form the <dfn
title="concept-appcache-onlinewhitelist">online whitelist
namespaces</dfn>.
<li>An <dfn
title="concept-appcache-onlinewhitelist-wildcard">online whitelist
wildcard flag</dfn>, which is either <i title="">open</i> or <i
title="">blocking</i>.</li>
</ul>
<p>Each <span>application cache</span> has a <dfn
title="concept-appcache-completeness">completeness flag</dfn>, which is
either <i>complete</i> or <i>incomplete</i>.</p>
<hr>
<p>An <dfn>application cache group</dfn> is a group of <span
title="application cache">application caches</span>, identified by
the <span>absolute URL</span> of a resource <span
title="concept-appcache-manifest">manifest</span> which is used to
populate the caches in the group.</p>
<p>An <span>application cache</span> is <dfn
title="concept-appcache-newer">newer</dfn> than another if it was
created after the other (in other words, <span title="application
cache">application caches</span> in an <span>application cache
group</span> have a chronological order).</p>
<p>Only the newest <span>application cache</span> in an
<span>application cache group</span> can have its <span
title="concept-appcache-completeness">completeness flag</span> set to
<i>incomplete</i>, the others are always all <i>complete</i>.</p>
<p>Each <span>application cache group</span> has an <dfn
title="concept-appcache-status">update status</dfn>, which is one of
the following: <i>idle</i>, <i>checking</i>, <i>downloading</i>.</p>
<p>A <dfn>relevant application cache</dfn> is an <span>application
cache</span> that is the <span
title="concept-appcache-newer">newest</span> in its <span
title="application cache group">group</span> to be
<i>complete</i>.</p>
<p>Each <span>application cache group</span> has a <dfn
title="concept-appcache-pending-masters">list of pending master
entries</dfn>. Each entry in this list consists of a resource and a
corresponding <code>Document</code> object. It is used during the
<span>application cache download process</span> to ensure that new
master entries are cached even if the <span>application cache
download process</span> was already running for their
<span>application cache group</span> when they were loaded.</p>
<p>An <span>application cache group</span> can be marked as <dfn
title="concept-appcache-obsolete">obsolete</dfn>, meaning that it
must be ignored when looking at what <span title="application cache
group">application cache groups</span> exist.</p>
<hr>
<p>A <dfn>cache host</dfn> is a <code>Document</code> or a
<code>SharedWorkerGlobalScope</code> object. A <span>cache
host</span> can be associated with an <span>application
cache</span>.
<!--END complete-->
<a href="#refsWEBWORKERS">[WEBWORKERS]</a>
<!--START complete-->
</p>
<p>A <code>Document</code> initially is not associated with an
<span>application cache</span>, but can become associated with one
early during the page load process, when steps <a
href="#parser-appcache">in the parser</a> and in the <span
title="navigate">navigation</span> sections cause <span
title="concept-appcache-init">cache selection</span> to occur.</p>
<p>A <code>SharedWorkerGlobalScope</code> can be associated with an
<span>application cache</span> when it is created.
<!--END complete-->
<a href="#refsWEBWORKERS">[WEBWORKERS]</a>
<!--START complete-->
</p>
<p>Each <span>cache host</span> has an associated
<code>ApplicationCache</code> object.</p>
<hr>
<p>Multiple <span title="application cache">application
caches</span> in different <span title="application cache
group">application cache groups</span> can contain the same
resource, e.g. if the manifests all reference that resource. If the
user agent is to <dfn title="concept-appcache-selection">select an
application cache</dfn> from a list of <span title="relevant
application cache">relevant application caches</span> that contain a
resource, the user agent must use the application cache that the
user most likely wants to see the resource from, taking into account
the following:</p>
<ul>
<li>which application cache was most recently updated,
<li>which application cache was being used to display the
resource from which the user decided to look at the new resource,
and
<li>which application cache the user prefers.
</ul>
<hr>
<p>A URL <dfn title="concept-appcache-matches-fallback">matches a
fallback namespace</dfn> if there exists a <span>relevant
application cache</span> whose <span
title="concept-appcache-manifest">manifest</span>'s URL has the
<span>same origin</span> as the URL in question, and that has a
<span title="concept-appcache-fallback-ns">fallback namespace</span>
that is a <span>prefix match</span> for the URL being examined. If
multiple fallback namespaces match the same URL, the longest one is
the one that matches. A URL looking for a fallback namespace can
match more than one application cache at a time, but only matches
one namespace in each cache.</p>
<div class="example">
<p>If a manifest <code
title="">http://example.com/app1/manifest</code> declares that
<code title="">http://example.com/resources/images</code> is a
fallback namespace, and the user navigates to <code
title="">HTTP://EXAMPLE.COM:80/resources/images/cat.png</code>,
then the user agent will decide that the application cache
identified by <code
title="">http://example.com/app1/manifest</code> contains a
namespace with a match for that URL.</p>
<!-- "resolve a url" canonicalises the case for the scheme and host
and removes the port if it is the default -->
</div>
</div>
<h4 id="manifests">The cache manifest syntax</h4>
<h5>A sample manifest</h5>
<p><i>This section is non-normative.</i></p>
<p>This example manifest requires two images and a style sheet to be
cached and whitelists a CGI script.</p>
<pre>CACHE MANIFEST
# the above line is required
# this is a comment
# there can be as many of these anywhere in the file
# they are all ignored
# comments can have spaces before them
# but must be alone on the line
# blank lines are ignored too
# these are files that need to be cached they can either be listed
# first, or a "CACHE:" header could be put before them, as is done
# lower down.
images/sound-icon.png
images/background.png
# note that each file has to be put on its own line
# here is a file for the online whitelist -- it isn't cached, and
# references to this file will bypass the cache, always hitting the
# network (or trying to, if the user is offline).
NETWORK:
comm.cgi
# here is another set of files to cache, this time just the CSS file.
CACHE:
style/default.css</pre>
<p>It could equally well be written as follows:</p>
<pre>CACHE MANIFEST
NETWORK:
comm.cgi
CACHE:
style/default.css
images/sound-icon.png
images/background.png</pre>
<hr>
<p>The following manifest defines a catch-all error page that is
displayed for any page on the site while the user is offline. It
also specifies that the <span
title="concept-appcache-onlinewhitelist-wildcard">online whitelist
wildcard flag</span> is <i title="">open</i>, meaning that accesses
to resources on other sites will not be blocked. (Resources on the
same site are already not blocked because of the catch-all fallback
namespace.)</p>
<p>So long as all pages on the site reference this manifest, they
will get cached locally as they are fetched, so that subsequent hits
to the same page will load the page immediately from the
cache. Until the manifest is changed, those pages will not be
fetched from the server again. When the manifest changes, then all
the files will be redownloaded.</p>
<p>Subresources, such as style sheets, images, etc, would only be
cached using the regular HTTP caching semantics, however.</p>
<pre>CACHE MANIFEST
FALLBACK:
/ /offline.html
NETWORK:
*</pre>
<h5>Writing cache manifests</h5>
<p>Manifests must be served using the
<code>text/cache-manifest</code> <span>MIME type</span>. All
resources served using the <code>text/cache-manifest</code>
<span>MIME type</span> must follow the syntax of application cache
manifests, as described in this section.</p>
<p>An application cache manifest is a text file, whose text is
encoded using UTF-8. Data in application cache manifests is
line-based. Newlines must be represented by U+000A LINE FEED (LF)
characters, U+000D CARRIAGE RETURN (CR) characters, or U+000D
CARRIAGE RETURN (CR) U+000A LINE FEED (LF) pairs.</p>
<p class="note">This is a <span>willful violation</span> of two
aspects of RFC 2046, which requires all <code title="">text/*</code>
types to support an open-ended set of character encodings and only
allows CRLF line breaks. These requirements, however, are outdated;
UTF-8 is now widely used, such that supporting other encodings is no
longer necessary, and use of CR, LF, and CRLF line breaks is
commonly supported and indeed sometimes CRLF is <em>not</em>
supported by text editors. <a href="#refsRFC2046">[RFC2046]</a></p>
<!-- also RFC 2045 for charset -->
<p>The first line of an application cache manifest must consist of
the string "CACHE", a single U+0020 SPACE character, the string
"MANIFEST", and either a U+0020 SPACE character, a U+0009 CHARACTER
TABULATION (tab) character, a U+000A LINE FEED (LF) character, or a
U+000D CARRIAGE RETURN (CR) character. The first line may optionally
be preceded by a U+FEFF BYTE ORDER MARK (BOM) character. If any
other text is found on the first line, it is ignored.</p>
<p>Subsequent lines, if any, must all be one of the following:</p>
<dl>
<dt>A blank line
<dd>
<p>Blank lines must consist of zero or more U+0020 SPACE and
U+0009 CHARACTER TABULATION (tab) characters only.</p>
<dt>A comment
<dd>
<p>Comment lines must consist of zero or more U+0020 SPACE and
U+0009 CHARACTER TABULATION (tab) characters, followed by a single
U+0023 NUMBER SIGN character (#), followed by zero or more
characters other than U+000A LINE FEED (LF) and U+000D CARRIAGE
RETURN (CR) characters.</p>
<p class="note">Comments must be on a line on their own. If they
were to be included on a line with a URL, the "#" would be
mistaken for part of a fragment identifier.</p>
<dt>A section header
<dd>
<p>Section headers change the current section. There are three
possible section headers:
<dl>
<dt><code>CACHE:</code>
<dd>Switches to the <dfn title="concept-appcache-manifest-explicit">explicit section</dfn>.
<dt><code>FALLBACK:</code>
<dd>Switches to the <dfn title="concept-appcache-manifest-fallback">fallback section</dfn>.
<dt><code>NETWORK:</code>
<dd>Switches to the <dfn title="concept-appcache-manifest-network">online whitelist section</dfn>.
</dl>
<p>Section header lines must consist of zero or more U+0020 SPACE
and U+0009 CHARACTER TABULATION (tab) characters, followed by one
of the names above (including the U+003A COLON character (:))
followed by zero or more U+0020 SPACE and U+0009 CHARACTER
TABULATION (tab) characters.</p>
<p>Ironically, by default, the current section is the
<span title="concept-appcache-manifest-explicit">explicit section</span>.</p>
<dt>Data for the current section
<dd>
<p>The format that data lines must take depends on the current
section.</p>
<p>When the current section is the <span
title="concept-appcache-manifest-explicit">explicit
section</span>, data lines must consist of zero or more U+0020
SPACE and U+0009 CHARACTER TABULATION (tab) characters, a
<span>valid URL</span> identifying a resource other than the
manifest itself, and then zero or more U+0020 SPACE and U+0009
CHARACTER TABULATION (tab) characters.</p>
<p>When the current section is the <span
title="concept-appcache-manifest-fallback">fallback
section</span>, data lines must consist of zero or more U+0020
SPACE and U+0009 CHARACTER TABULATION (tab) characters, a
<span>valid URL</span> identifying a resource other than the
manifest itself, one or more U+0020 SPACE and U+0009 CHARACTER
TABULATION (tab) characters, another <span>valid URL</span>
identifying a resource other than the manifest itself, and then
zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab)
characters.</p>
<p>When the current section is the <span
title="concept-appcache-manifest-network">online whitelist
section</span>, data lines must consist of zero or more U+0020
SPACE and U+0009 CHARACTER TABULATION (tab) characters, either a
single U+002A ASTERISK character (*) <!--
concept-appcache-onlinewhitelist-wildcard --> or a <span>valid
URL</span> identifying a resource other than the manifest itself,
and then zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION
(tab) characters.</p>
<!--
<p class="note">The URLs in data lines can't be empty strings,
since those would be relative URLs to the manifest itself. Such
lines would be confused with blank or invalid lines, anyway.</p>
-->
</dl>
<p>Manifests may contain sections more than once. Sections may be
empty.</p>
<p>URLs that are to be fallback pages associated with <span
title="concept-appcache-fallback-ns">fallback namespaces</span>, and
those namespaces themselves, must be given in <span
title="concept-appcache-manifest-fallback">fallback sections</span>,
with the namespace being the first URL of the data line, and the
corresponding fallback page being the second URL. All the other
pages to be cached must be listed in <span
title="concept-appcache-manifest-explicit">explicit
sections</span>.</p>
<p><span title="concept-appcache-fallback-ns">Fallback
namespaces</span> and <span
title="concept-appcache-fallback">fallback entries</span> must have
the <span>same origin</span> as the manifest itself.</p>
<p>A <span title="concept-appcache-fallback-ns">fallback
namespace</span> must not be listed more than once.</p>
<p>Namespaces that the user agent is to put into the <span
title="concept-appcache-onlinewhitelist">online whitelist</span>
must all be specified in <span
title="concept-appcache-manifest-network">online whitelist
sections</span>. (This is needed for any URL that the page is
intending to use to communicate back to the server.) To specify that
all URLs are automatically whitelisted in this way, a U+002A
ASTERISK character character (*) may be specified as one of the
URLs. <!-- concept-appcache-onlinewhitelist-wildcard --></p>
<p>Authors should not include namespaces in the <span
title="concept-appcache-onlinewhitelist">online whitelist</span> for
which another namespace in the <span
title="concept-appcache-onlinewhitelist">online whitelist</span> is
a <span>prefix match</span>.</p>
<p>Relative URLs must be given relative to the manifest's own
URL. All URLs in the manifest must have the same <span
title="url-scheme"><scheme></span> as the manifest itself
(either explicitly or implicitly, through the use of relative
URLs).</p>
<p>URLs in manifests must not have fragment identifiers (i.e. the
U+0023 NUMBER SIGN character isn't allowed in URLs in
manifests).</p>
<p><span title="concept-appcache-fallback-ns">Fallback
namespaces</span> and namespaces in the <span
title="concept-appcache-onlinewhitelist">online whitelist</span> are
matched by <span>prefix match</span>.</p>
<div class="impl">
<h5>Parsing cache manifests</h5>
<p>When a user agent is to <dfn>parse a manifest</dfn>, it means
that the user agent must run the following steps:</p>
<ol>
<li><p>The user agent must decode the byte stream corresponding with
the manifest to be parsed, treating it as UTF-8. Bytes or sequences
of bytes that are not valid UTF-8 sequences must be interpreted as
a U+FFFD REPLACEMENT CHARACTER. <!--All U+0000 NULL characters must
be replaced by U+FFFD REPLACEMENT CHARACTERs. (this isn't black-box
testable since neither U+0000 nor U+FFFD are valid anywhere in the
syntax and thus both will be treated the same anyway)--></p></li>
<li><p>Let <var title="">base URL</var> be the <span>absolute
URL</span> representing the manifest.</p></li>
<li><p>Let <var title="">explicit URLs</var> be an initially empty
list of <span title="absolute URL">absolute URLs</span> for <span
title="concept-appcache-explicit">explicit entries</span>.</p></li>
<li><p>Let <var title="">fallback URLs</var> be an initially empty
mapping of <span title="concept-appcache-fallback-ns">fallback
namespaces</span> to <span title="absolute URL">absolute
URLs</span> for <span title="concept-appcache-fallback">fallback
entries</span>.</p></li>
<li><p>Let <var title="">online whitelist namespaces</var> be an
initially empty list of <span title="absolute URL">absolute
URLs</span> for an <span
title="concept-appcache-onlinewhitelist">online
whitelist</span>.</p></li>
<li><p>Let <var title="">online whitelist wildcard flag</var> be <i
title="">blocking</i>. <!--
concept-appcache-onlinewhitelist-wildcard --></p></li>
<li><p>Let <var title="">input</var> be the decoded text of the
manifest's byte stream.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the first
character.</p></li>
<li><p>If <var title="">position</var> is pointing at a U+FEFF BYTE
ORDER MARK (BOM) character, then advance <var
title="">position</var> to the next character.</p></li>
<li><p>If the characters starting from <var title="">position</var>
are "CACHE", followed by a U+0020 SPACE character, followed by
"MANIFEST", then advance <var title="">position</var> to the next
character after those. Otherwise, this isn't a cache manifest;
abort this algorithm with a failure while checking for the magic
signature.</p></li>
<li><p>If the character at <var title="">position</var> is neither
a U+0020 SPACE character, a U+0009 CHARACTER TABULATION (tab)
character, U+000A LINE FEED (LF) character, nor a U+000D CARRIAGE
RETURN (CR) character, then this isn't a cache manifest; abort this
algorithm with a failure while checking for the magic
signature.</p></li>
<li><p>This is a cache manifest. The algorithm cannot fail beyond
this point (though bogus lines can get ignored).</p></li>
<li><p><span>Collect a sequence of characters</span> that are
<em>not</em> U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR)
characters, and ignore those characters. (Extra text on the first
line, after the signature, is ignored.)</p></li>
<li><p>Let <var title="">mode</var> be "explicit".</p></li>
<li><p><i>Start of line</i>: If <var title="">position</var> is
past the end of <var title="">input</var>, then jump to the last
step. Otherwise, <span>collect a sequence of characters</span> that
are U+000A LINE FEED (LF), U+000D CARRIAGE RETURN (CR), U+0020
SPACE, or U+0009 CHARACTER TABULATION (tab) characters.</p></li>
<!-- strips leading spaces, ignores space-only lines, ignores blank lines -->
<li><p>Now, <span>collect a sequence of characters</span> that are
<em>not</em> U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR)
characters, and let the result be <var
title="">line</var>.</p></li>
<li><p>Drop any trailing U+0020 SPACE and U+0009 CHARACTER
TABULATION (tab) characters at the end of <var
title="">line</var>.</p></li>
<li><p>If <var title="">line</var> is the empty string, then jump
back to the step labeled "start of line".</p></li>
<li><p>If the first character in <var title="">line</var> is a
U+0023 NUMBER SIGN character (#), then jump back to the step
labeled "start of line".</p></li>
<li><p>If <var title="">line</var> equals "CACHE:" (the word
"CACHE" followed by a U+003A COLON character (:)), then set <var
title="">mode</var> to "explicit" and jump back to the step
labeled "start of line".</p></li>
<li><p>If <var title="">line</var> equals "FALLBACK:" (the word
"FALLBACK" followed by a U+003A COLON character (:)), then set <var
title="">mode</var> to "fallback" and jump back to the step
labeled "start of line".</p></li>
<li><p>If <var title="">line</var> equals "NETWORK:" (the word
"NETWORK" followed by a U+003A COLON character (:)), then set <var
title="">mode</var> to "online whitelist" and jump back to the step
labeled "start of line".</p></li>
<li><p>If <var title="">line</var> ends with a U+003A COLON
character (:), then set <var title="">mode</var> to "unknown" and
jump back to the step labeled "start of line".</p></li>
<li><p>This is either a data line or it is syntactically
incorrect.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">line</var>, initially pointing at the start of the
string.</p></li>
<li><p>Let <var title="">tokens</var> be a list of strings,
initially empty.</p></li>
<li>
<p>While <var title="">position</var> doesn't point past the end
of <var title="">line</var>:</p>
<ol>
<li><p>Let <var title="">current token</var> be an empty
string.</p></li>
<li><p>While <var title="">position</var> doesn't point past the
end of <var title="">line</var> and the character at <var
title="">position</var> is neither a U+0020 SPACE nor a U+0009
CHARACTER TABULATION (tab) character, add the character at <var
title="">position</var> to <var title="">current token</var> and
advance <var title="">position</var> to the next character in
<var title="">input</var>.</p></li>
<li><p>Add <var title="">current token</var> to the <var
title="">tokens</var> list.</p></li>
<li><p>While <var title="">position</var> doesn't point past the
end of <var title="">line</var> and the character at <var
title="">position</var> is either a U+0020 SPACE or a U+0009
CHARACTER TABULATION (tab) character, advance <var
title="">position</var> to the next character in <var
title="">input</var>.</p></li>
</ol>
</li>
<li>
<p>Process <var title="">tokens</var> as follows:</p>
<dl class="switch">
<dt>If <var title="">mode</var> is "explicit"</dt>
<dd>
<p><span title="resolve a url">Resolve</span> the first item in
<var title="">tokens</var>, relative to <var title="">base
URL</var>; ignore the rest.</p>
<p>If this fails, then jump back to the step labeled "start of
line".</p>
<p>If the resulting <span>absolute URL</span> has a different
<span title="url-scheme"><scheme></span> component than
the manifest's URL (compared in an <span>ASCII
case-insensitive</span> manner), then jump back to the step
labeled "start of line".</p>
<p>Drop the <span title="url-fragment"><fragment></span>
component of the resulting <span>absolute URL</span>, if it has
one.</p>
<p>Add the resulting <span>absolute URL</span> to the <var
title="">explicit URLs</var>.</p>
</dd>
<dt>If <var title="">mode</var> is "fallback"</dt>
<dd>
<p>Let <var title="">part one</var> be the first token in <var
title="">tokens</var>, and let <var title="">part two</var> be
the second token in <var title="">tokens</var>.</p>
<p><span title="resolve a url">Resolve</span> <var title="">part
one</var> and <var title="">part two</var>, relative to <var
title="">base URL</var>.</p>
<p>If either fails, then jump back to the step labeled "start of
line".</p>
<p>If the <span>absolute URL</span> corresponding to either <var
title="">part one</var> or <var title="">part two</var> does not
have the <span>same origin</span> as the manifest's URL, then
jump back to the step labeled "start of line".</p> <!-- SECURITY
-->
<p>Drop any the <span
title="url-fragment"><fragment></span> components of the
resulting <span title="absolute URL">absolute URLs</span>.</p>
<p>If the <span>absolute URL</span> corresponding to <var
title="">part one</var> is already in the <var title="">fallback
URLs</var> mapping as a <span
title="concept-appcache-fallback-ns">fallback namespace</span>,
then jump back to the step labeled "start of line".</p>
<p>Otherwise, add the <span>absolute URL</span> corresponding to
<var title="">part one</var> to the <var title="">fallback
URLs</var> mapping as a <span
title="concept-appcache-fallback-ns">fallback namespace</span>,
mapped to the <span>absolute URL</span> corresponding to <var
title="">part two</var> as the <span
title="concept-appcache-fallback">fallback entry</span>.</p>
</dd>
<dt>If <var title="">mode</var> is "online whitelist"</dt>
<dd>
<p>If the first item in <var title="">tokens</var> is a U+002A
ASTERISK character (*), then set <var title="">online whitelist
wildcard flag</var> to <i title="">open</i> and jump back to the
step labeled "start of line".</p>
<p>Otherwise, <span title="resolve a url">resolve</span> the
first item in <var title="">tokens</var>, relative to <var
title="">base URL</var>; ignore the rest.</p>
<p>If this fails, then jump back to the step labeled "start of
line".</p>
<p>If the resulting <span>absolute URL</span> has a different
<span title="url-scheme"><scheme></span> component than
the manifest's URL (compared in an <span>ASCII
case-insensitive</span> manner), then jump back to the step
labeled "start of line".</p>
<p>Drop the <span title="url-fragment"><fragment></span>
component of the resulting <span>absolute URL</span>, if it has
one.</p>
<p>Add the resulting <span>absolute URL</span> to the <var
title="">online whitelist namespaces</var>.</p>
</dd>
<dt>If <var title="">mode</var> is "unknown"</dt>
<dd>
<p>Do nothing. The line is ignored.</p>
</dd>
</dl>
</li>
<li><p>Jump back to the step labeled "start of line". (That step
jumps to the next, and last, step when the end of the file is
reached.)</p></li>
<li><p>Return the <var title="">explicit URLs</var> list, the <var
title="">fallback URLs</var> mapping, the <var title="">online
whitelist namespaces</var>, and the <var title="">online whitelist
wildcard flag</var>.</p></li>
</ol>
<div class="note">
<p>If a resource is listed in the <span
title="concept-appcache-manifest-explicit">explicit section</span>
or as a <span title="concept-appcache-fallback">fallback
entry</span> in the <span
title="concept-appcache-manifest-fallback">fallback section</span>,
the resource will always be taken from the cache, regardless of any
other matching entries in the <span
title="concept-appcache-fallback-ns">fallback namespaces</span> or
<span title="concept-appcache-onlinewhitelist">online whitelist
namespaces</span>.</p>
<p>When a <span title="concept-appcache-fallback-ns">fallback
namespace</span> and an <span
title="concept-appcache-onlinewhitelist">online whitelist
namespace</span> overlap, the <span
title="concept-appcache-onlinewhitelist">online whitelist
namespace</span> has priority.</p>
<p>The <span
title="concept-appcache-onlinewhitelist-wildcard">online whitelist
wildcard flag</span> is applied last, only for URLs that match
neither the <span title="concept-appcache-onlinewhitelist">online
whitelist namespace</span> nor the <span
title="concept-appcache-fallback-ns">fallback namespace</span> and
that are not listed in the <span
title="concept-appcache-manifest-explicit">explicit
section</span>.</p>
</div>
<h4>Downloading or updating an application cache</h4>
<p>When the user agent is required (by other parts of this
specification) to start the <dfn>application cache download
process</dfn> for an <span>absolute URL</span> purported to identify
a <span title="concept-appcache-manifest">manifest</span>, or for an
<span>application cache group</span>, potentially given a particular
<span>cache host</span>, and potentially given a <span
title="concept-appcache-master">master</span> resource, the user
agent must run the steps below.</p>
<p>Some of these steps have requirements that only apply if the user
agent <dfn>shows caching progress</dfn>. Support for this is
optional. Caching progress UI could consist of a progress bar or
message panel in the user agent's interface, or an overlay, or
something else. Certain events fired during the <span>application
cache download process</span> allow the script to override the display
of such an interface. The goal of this is to allow Web applications
to provide more seamless update mechanisms, hiding from the user the
mechanics of the application cache mechanism. User agents may
display user interfaces independent of this, but are encouraged to
not show prominent update progress notifications for applications
that cancel the relevant events.</p>
<p>The <span>application cache download process</span> steps are as
follows:
<ol>
<li><p>Optionally, wait until the permission to start the
<span>application cache download process</span> has been obtained
from the user and until the user agent is confident that the
network is available. This could include doing nothing until the
user explicitly opts-in to caching the site, or could involve
prompting the user for permission. The algorithm might never get
past this point. (This step is particularly intended to be used by
user agents running on severely space-constrained devices or in
highly privacy-sensitive environments).</p></li>
<li>
<p>Atomically, so as to avoid race conditions, perform the
following substeps:</p>
<ol>
<li>
<p>Pick the appropriate substeps:</p>
<dl class="switch">
<dt>If these steps were invoked with an <span>absolute
URL</span> purported to identify a <span
title="concept-appcache-manifest">manifest</span></dt>
<dd>
<p>Let <var title="">manifest URL</var> be that <span>absolute
URL</span>.</p>
<p>If there is no <span>application cache group</span>
identified by <var title="">manifest URL</var>, then create a
new <span>application cache group</span> identified by <var
title="">manifest URL</var>. Initially, it has no <span
title="application cache">application caches</span>. One will
be created later in this algorithm.</p>
</dd>
<dt>If these steps were invoked with an <span>application cache
group</span></dt>
<dd>
<p>Let <var title="">manifest URL</var> be the <span>absolute
URL</span> of the <span
title="concept-appcache-manifest">manifest</span> used to
identify the <span>application cache group</span> to be
updated.</p>
</dd>
</dl>
</li>
<li><p>Let <var title="">cache group</var> be the
<span>application cache group</span> identified by <var
title="">manifest URL</var>.</p></li>
<li><p>If these steps were invoked with a <span
title="concept-appcache-master">master</span> resource, then add
the resource, along with the resource's <code>Document</code>, to
<var title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>.</p></li>
<li><p>If these steps were invoked with a <span>cache
host</span>, and the <span
title="concept-appcache-status">status</span> of <var
title="">cache group</var> is <i>checking</i> or
<i>downloading</i>, then <span>queue a task</span> to <span>fire
a simple event</span> named <code
title="event-appcache-checking">checking</code> that is
cancelable at the <code>ApplicationCache</code> singleton of that
<span>cache host</span>. The default action of this event must
be, if the user agent <span>shows caching progress</span>, the
display of some sort of user interface indicating to the user
that the user agent is checking to see if it can download the
application.</p></li>
<li><p>If these steps were invoked with a <span>cache
host</span>, and the <span
title="concept-appcache-status">status</span> of <var
title="">cache group</var> is <i>downloading</i>, then also
<span>queue a task</span> to <span>fire a simple event</span>
named <code
title="event-appcache-downloading">downloading</code> that is
cancelable at the <code>ApplicationCache</code> singleton of that
<span>cache host</span>. The default action of this event must
be, if the user agent <span>shows caching progress</span>, the
display of some sort of user interface indicating to the user the
application is being downloaded.</p></li>
<li><p>If the <span title="concept-appcache-status">status</span>
of the <var title="">cache group</var> is either <i>checking</i>
or <i>downloading</i>, then abort this instance of the
<span>application cache download process</span>, as an update is
already in progress.</p></li>
<li><p>Set the <span
title="concept-appcache-status">status</span> of <var
title="">cache group</var> to <i>checking</i>.</p>
<li><p>For each <span>cache host</span> associated with an
<span>application cache</span> in <var title="">cache
group</var>, <span>queue a task</span> to <span>fire a simple
event</span> that is cancelable named <code
title="event-appcache-checking">checking</code> at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span>. The default action of these events must be, if the
user agent <span>shows caching progress</span>, the display of
some sort of user interface indicating to the user that the user
agent is checking for the availability of updates.</p></li>
</ol>
<p>The remainder of the steps run asynchronously.</p>
<p>If <var title="">cache group</var> already has an
<span>application cache</span> in it, then this is an <dfn
title="concept-appcache-upgrade">upgrade attempt</dfn>. Otherwise,
this is a <dfn title="concept-appcache-cache">cache
attempt</dfn>.</p>
</li>
<li><p>If this is a <span title="concept-appcache-cache">cache
attempt</span>, then this algorithm was invoked with a <span>cache
host</span>; <span>queue a task</span> to <span>fire a simple
event</span> named <code
title="event-appcache-checking">checking</code> that is cancelable
at the <code>ApplicationCache</code> singleton of that <span>cache
host</span>. The default action of this event must be, if the user
agent <span>shows caching progress</span>, the display of some sort
of user interface indicating to the user that the user agent is
checking for the availability of updates.</p></li>
<li>
<p><i>Fetching the manifest</i>: <span>Fetch</span> the resource
from <var title="">manifest URL</var>, and let <var
title="">manifest</var> be that resource.</p> <!-- http-origin
privacy sensitive, though it doesn't matter, since this can never
be cross-origin -->
<p>If the resource is labeled with the <span>MIME type</span>
<code>text/cache-manifest</code>, parse <var
title="">manifest</var> according to the <span title="parse a
manifest">rules for parsing manifests</span>, obtaining a list of
<span title="concept-appcache-explicit">explicit entries</span>,
<span title="concept-appcache-fallback">fallback entries</span>
and the <span title="concept-appcache-fallback-ns">fallback
namespaces</span> that map to them, entries for the <span
title="concept-appcache-onlinewhitelist">online whitelist</span>,
and a value for the <span
title="concept-appcache-onlinewhitelist-wildcard">online whitelist
wildcard flag</span>.</p>
</li>
<li>
<p>If <i>fetching the manifest</i> fails due to a 404 or 410
response <span title="concept-http-equivalent-codes">or
equivalent</span>, then run these substeps:</p>
<ol>
<li><p>Mark <var title="">cache group</var> as <span
title="concept-appcache-obsolete">obsolete</span>. This <var
title="">cache group</var> no longer exists for any purpose other
than the processing of <code>Document</code> objects already
associated with an <span>application cache</span> in the <var
title="">cache group</var>.</p></li>
<li><p>Let <var title="">task list</var> be an empty list of
<span title="concept-task">tasks</span>.</p>
<li><p>For each <span>cache host</span> associated with an
<span>application cache</span> in <var title="">cache
group</var>, create a <span title="concept-task">task</span> to
<span>fire a simple event</span> named <code
title="event-appcache-obsolete">obsolete</code> that is
cancelable at the <code>ApplicationCache</code> singleton of the
<span>cache host</span>, and add it to <var title="">task
list</var>. The default action of these events must be, if the
user agent <span>shows caching progress</span>, the display of
some sort of user interface indicating to the user that the
application is no longer available for offline use.</p></li>
<li><p>For each entry in <var title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>, create a <span title="concept-task">task</span>
to <span>fire a simple event</span> that is cancelable named
<code title="event-appcache-error">error</code> (not <code
title="event-appcache-obsolete">obsolete</code>!) at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span> the <code>Document</code> for this entry, if there
still is one, and add it to <var title="">task list</var>. The
default action of this event must be, if the user agent
<span>shows caching progress</span>, the display of some sort of
user interface indicating to the user that the user agent failed
to save the application for offline use.</p></li>
<li><p>If <var title="">cache group</var> has an
<span>application cache</span> whose <span
title="concept-appcache-completeness">completeness flag</span> is
<i>incomplete</i>, then discard that <span>application
cache</span>.</p>
<li><p>If appropriate, remove any user interface indicating that
an update for this cache is in progress.</p></li>
<li><p>Let the <span
title="concept-appcache-status">status</span> of <var
title="">cache group</var> be <i>idle</i>.</p></li>
<li><p>For each <span title="concept-task">task</span> in <var
title="">task list</var>, <span title="queue a task">queue</span>
that task.</p></li>
<li><p>Abort the <span>application cache download
process</span>.</p></li>
</ol>
</li>
<li>
<p>Otherwise, if <i>fetching the manifest</i> fails in some other
way (e.g. the server returns another 4xx or 5xx response <span
title="concept-http-equivalent-codes">or equivalent</span>, or
there is a DNS error, or the connection times out, or the user
cancels the download, or the parser for manifests fails when
checking the magic signature), or if the server returned a
redirect, or if the resource is labeled with a <span>MIME
type</span> other than <code>text/cache-manifest</code>, then run
the <span>cache failure steps</span>.</p>
</li>
<li>
<p>If this is an <span title="concept-appcache-upgrade">upgrade
attempt</span> and the newly downloaded <var
title="">manifest</var> is byte-for-byte identical to the manifest
found in the <span title="concept-appcache-newer">newest</span>
<span>application cache</span> in <var title="">cache group</var>,
or the server reported it as "304 Not Modified" <span
title="concept-http-equivalent-codes">or equivalent</span>, then
run these substeps:</p>
<ol>
<li><p>Let <var title="">cache</var> be the <span
title="concept-appcache-newer">newest</span> <span>application
cache</span> in <var title="">cache group</var>.</p></li>
<li><p>Let <var title="">task list</var> be an empty list of
<span title="concept-task">tasks</span>.</p>
<li>
<p>For each entry in <var title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>, wait for the resource for this entry to have
either completely downloaded or failed.</p>
<p>If the download failed (e.g. the connection times out, or the
user cancels the download), then create a <span
title="concept-task">task</span> to <span>fire a simple
event</span> that is cancelable named <code
title="event-appcache-error">error</code> at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span> the <code>Document</code> for this entry, if there
still is one, and add it to <var title="">task list</var>. The
default action of this event must be, if the user agent
<span>shows caching progress</span>, the display of some sort of
user interface indicating to the user that the user agent failed
to save the application for offline use.</p>
<p>Otherwise, associate the <code>Document</code> for this entry
with <var title="">cache</var>; store the resource for this
entry in <var title="">cache</var>, if it isn't already there,
and categorize its entry as a <span
title="concept-appcache-master">master entry</span>. If the
resource's <span>URL</span> has a <span
title="url-fragment"><fragment></span> component, it must
be removed from the entry in <var title="">cache</var>
(application caches never include fragment identifiers).</p>
<p class="note">HTTP caching rules, such as <code
title="">Cache-Control: no-store</code>, are ignored for the
purposes of the <span>application cache download
process</span>.</p>
</li>
<li><p>For each <span>cache host</span> associated with an
<span>application cache</span> in <var title="">cache
group</var>, create a <span title="concept-task">task</span> to
<span>fire a simple event</span> that is cancelable named <code
title="event-appcache-noupdate">noupdate</code> at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span>, and add it to <var title="">task list</var>. The
default action of these events must be, if the user agent
<span>shows caching progress</span>, the display of some sort of
user interface indicating to the user that the application is up
to date.</p></li>
<li><p>Empty <var title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>.</p></li>
<li><p>If appropriate, remove any user interface indicating that
an update for this cache is in progress.</p></li>
<li><p>Let the <span
title="concept-appcache-status">status</span> of <var
title="">cache group</var> be <i>idle</i>.</p></li>
<li><p>For each <span title="concept-task">task</span> in <var
title="">task list</var>, <span title="queue a task">queue</span>
that task.</p></li>
<li><p>Abort the <span>application cache download
process</span>.</p></li>
</ol>
</li>
<li><p>Let <var title="">new cache</var> be a newly created
<span>application cache</span> in <var title="">cache
group</var>. Set its <span
title="concept-appcache-completeness">completeness flag</span> to
<i>incomplete</i>.</p></li>
<li><p>For each entry in <var title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>, associate the <code>Document</code> for this entry
with <var title="">new cache</var>.</p></li>
<li><p>Set the <span title="concept-appcache-status">status</span>
of <var title="">cache group</var> to <i>downloading</i>.</p></li>
<li><p>For each <span>cache host</span> associated with an
<span>application cache</span> in <var title="">cache group</var>,
<span>queue a task</span> to <span>fire a simple event</span> that
is cancelable named <code
title="event-appcache-downloading">downloading</code> at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span>. The default action of these events must be, if the
user agent <span>shows caching progress</span>, the display of some
sort of user interface indicating to the user that a new version is
being downloaded.</p></li>
<li><p>Let <var title="">file list</var> be an empty list of
URLs with flags.</p></li>
<li><p>Add all the URLs in the list of <span
title="concept-appcache-explicit">explicit entries</span> obtained
by parsing <var title="">manifest</var> to <var title="">file
list</var>, each flagged with "explicit entry".</p></li>
<li><p>Add all the URLs in the list of <span
title="concept-appcache-fallback">fallback entries</span> obtained
by parsing <var title="">manifest</var> to <var title="">file
list</var>, each flagged with "fallback entry".</p></li>
<li><p>If this is an <span title="concept-appcache-upgrade">upgrade
attempt</span>, then add all the URLs of <span
title="concept-appcache-master">master entries</span> in the <span
title="concept-appcache-newer">newest</span> <span>application
cache</span> in <var title="">cache group</var> whose <span
title="concept-appcache-completeness">completeness flag</span> is
<i>complete</i> to <var title="">file list</var>, each flagged with
"master entry".</p></li>
<li><p>If any URL is in <var title="">file list</var> more than
once, then merge the entries into one entry for that URL, that
entry having all the flags that the original entries had.</p></li>
<li>
<p>For each URL in <var title="">file list</var>, run the
following steps. These steps may be run in parallel for two or
more of the URLs at a time.</p>
<ol>
<li>
<p>If the resource URL being processed was flagged as neither an
"explicit entry" nor or a "fallback entry", then the user agent
may skip this URL.</p>
<p class="note">This is intended to allow user agents to expire
resources not listed in the manifest from the cache. Generally,
implementors are urged to use an approach that expires
lesser-used resources first.</p>
</li>
<li><p>For each <span>cache host</span> associated with an
<span>application cache</span> in <var title="">cache
group</var>, <span>queue a task</span> to fire an event with the
name <code title="event-appcache-progress">progress</code>, which
does not bubble, which is cancelable, and which uses the
<code>ProgressEvent</code> interface, at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span>. The <code
title="dom-ProgressEvents-lengthComputable">lengthComputable</code>
attribute must be set to true, the <code
title="dom-ProgressEvents-total">total</code> attribute must be
set to the number of files in <var title="">file list</var>, and
the <code title="dom-ProgressEvents-loaded">loaded</code>
attribute must be set to the number of number of files in <var
title="">file list</var> that have been either downloaded or
skipped so far. The default action of these events must be, if
the user agent <span>shows caching progress</span>, the display
of some sort of user interface indicating to the user that a file
is being downloaded in preparation for updating the
application. <a href="#refsPROGRESS">[PROGRESS]</a></p></li>
<li>
<p><span>Fetch</span> the resource, from the <span>origin</span>
of the <span>URL</span> <var title="">manifest URL</var>. If
this is an <span title="concept-appcache-upgrade">upgrade
attempt</span>, then use the <span
title="concept-appcache-newer">newest</span> <span>application
cache</span> in <var title="">cache group</var> as an HTTP
cache, and honor HTTP caching semantics (such as expiration,
ETags, and so forth) with respect to that cache. User agents may
also have other caches in place that are also honored.</p> <!--
not http-origin privacy sensitive -->
<p class="note">If the resource in question is already being
downloaded for other reasons then the existing download process
can sometimes be used for the purposes of this step, as defined
by the <span title="fetch">fetching</span> algorithm.</p>
<p class="example">An example of a resource that might already
be being downloaded is a large image on a Web page that is being
seen for the first time. The image would get downloaded to
satisfy the <code>img</code> element on the page, as well as
being listed in the cache manifest. According to the rules for
<span title="fetch">fetching</span> that image only need be
downloaded once, and it can be used both for the cache and for
the rendered Web page.</p>
</li>
<li>
<p>If the previous step fails (e.g. the server returns a 4xx or
5xx response <span title="concept-http-equivalent-codes">or
equivalent</span>, or there is a DNS error, or the connection
times out, or the user cancels the download), or if the server
returned a redirect, then run the first appropriate step from
the following list:</p>
<dl class="switch">
<dt>If the URL being processed was flagged as an "explicit
entry" or a "fallback entry"</dt>
<dd>
<p>Run the <span>cache failure steps</span>.</p>
<p class="note">Redirects are fatal because they are either
indicative of a network problem (e.g. a captive portal); or
would allow resources to be added to the cache under URLs that
differ from any URL that the networking model will allow
access to, leaving orphan entries; or would allow resources to
be stored under URLs different than their true URLs. All of
these situations are bad.</p>
</dd>
<dt>If the error was a 404 or 410 HTTP response <span
title="concept-http-equivalent-codes">or equivalent</span></dt>
<dd>
<p>Skip this resource. It is dropped from the cache.</p>
</dd>
<dt>Otherwise</dt>
<dd>
<p>Copy the resource and its metadata from the <span
title="concept-appcache-newer">newest</span> <span>application
cache</span> in <var title="">cache group</var> whose <span
title="concept-appcache-completeness">completeness flag</span>
is <i>complete</i>, and act as if that was the fetched
resource, ignoring the resource obtained from the network.</p>
</dd>
</dl>
<p>User agents may warn the user of these errors as an aid to
development.</p>
<p class="note">These rules make errors for resources listed in
the manifest fatal, while making it possible for other resources
to be removed from caches when they are removed from the server,
without errors, and making non-manifest resources survive
server-side errors.</p>
</li>
<li><p>Otherwise, the fetching succeeded. Store the resource in
the <var title="">new cache</var>.</p></li>
<li><p>If the URL being processed was flagged as an "explicit
entry" in <var title="">file list</var>, then categorize the
entry as an <span title="concept-appcache-explicit">explicit
entry</span>.</p></li>
<li><p>If the URL being processed was flagged as a "fallback
entry" in <var title="">file list</var>, then categorize the
entry as a <span title="concept-appcache-fallback">fallback
entry</span>.</p></li>
<li><p>If the URL being processed was flagged as an "master
entry" in <var title="">file list</var>, then categorize the
entry as a <span title="concept-appcache-master">master
entry</span>.</p></li>
<li><p>As an optimization, if the resource is an HTML or XML file
whose root element is an <code>html</code> element with a <code
title="attr-html-manifest">manifest</code> attribute whose value
doesn't match the manifest URL of the application cache being
processed, then the user agent should mark the entry as being
<span title="concept-appcache-foreign">foreign</span>.</p>
</ol>
</li>
<li><p>For each <span>cache host</span> associated with an
<span>application cache</span> in <var title="">cache group</var>,
<span>queue a task</span> to fire an event with the name <code
title="event-appcache-progress">progress</code>, which does not
bubble, which is cancelable, and which uses the
<code>ProgressEvent</code> interface, at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span>. The <code
title="dom-ProgressEvents-lengthComputable">lengthComputable</code>
attribute must be set to true, the <code
title="dom-ProgressEvents-total">total</code> and the <code
title="dom-ProgressEvents-loaded">loaded</code> attributes must be
set to the number of number of files in <var title="">file
list</var>. The default action of these events must be, if the user
agent <span>shows caching progress</span>, the display of some sort
of user interface indicating to the user that all the files have
been downloaded. <a href="#refsPROGRESS">[PROGRESS]</a></p></li>
<li><p>Store the list of <span
title="concept-appcache-fallback-ns">fallback namespaces</span>,
and the URLs of the <span
title="concept-appcache-fallback">fallback entries</span> that they
map to, in <var title="">new cache</var>.</p></li>
<li><p>Store the URLs that form the new <span
title="concept-appcache-onlinewhitelist">online whitelist</span> in
<var title="">new cache</var>.</p></li>
<li><p>Store the value of the new <span
title="concept-appcache-onlinewhitelist-wildcard">online whitelist
wildcard flag</span> in <var title="">new cache</var>.</p></li>
<li>
<p>For each entry in <var title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>, wait for the resource for this entry to have
either completely downloaded or failed.</p>
<p>If the download failed (e.g. the connection times out, or the
user cancels the download), then run these substeps:</p>
<ol>
<li><p>Unassociate the <code>Document</code> for this entry from
<var title="">new cache</var>.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> that is cancelable named <code
title="event-appcache-error">error</code> at the
<code>ApplicationCache</code> singleton of the
<code>Document</code> for this entry, if there still is one. The
default action of this event must be, if the user agent
<span>shows caching progress</span>, the display of some sort of
user interface indicating to the user that the user agent failed
to save the application for offline use.</p>
<li>
<p>If this is a <span title="concept-appcache-cache">cache
attempt</span> and this entry is the last entry in <var
title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>, then run these further substeps:</p>
<ol>
<li><p>Discard <var title="">cache group</var> and its only
<span>application cache</span>, <var title="">new
cache</var>.</p>
<li><p>If appropriate, remove any user interface indicating
that an update for this cache is in progress.</p></li>
<li><p>Abort the <span>application cache download
process</span>.</p></li>
</ol>
</li>
<li><p>Otherwise, remove this entry from <var title="">cache
group</var>'s <span title="concept-appcache-pending-masters">list
of pending master entries</span>.</p></li>
</ol>
<p>Otherwise, store the resource for this entry in <var
title="">new cache</var>, if it isn't already there, and
categorize its entry as a <span
title="concept-appcache-master">master entry</span>.</p>
</li>
<li>
<p><span>Fetch</span> the resource from <var title="">manifest
URL</var> again, and let <var title="">second manifest</var> be
that resource.</p> <!-- http-origin privacy sensitive, though it
doesn't matter, since this can never be cross-origin -->
</li>
<li>
<p>If the previous step failed for any reason, or if the fetching
attempt involved a redirect, or if <var title="">second
manifest</var> and <var title="">manifest</var> are not
byte-for-byte identical, then schedule a rerun of the entire
algorithm with the same parameters after a short delay, and run
the <span>cache failure steps</span>.</p>
</li>
<li>
<p>Otherwise, store <var title="">manifest</var> in <var
title="">new cache</var>, if it's not there already, and
categorize its entry as <span
title="concept-appcache-manifest">the manifest</span>.</p>
</li>
<li><p>Set the <span
title="concept-appcache-completeness">completeness flag</span> of
<var title="">new cache</var> to <i>complete</i>.</p></li>
<li><p>Let <var title="">task list</var> be an empty list of <span
title="concept-task">tasks</span>.</p>
<li>
<p>If this is a <span title="concept-appcache-cache">cache
attempt</span>, then for each <span>cache host</span> associated
with an <span>application cache</span> in <var title="">cache
group</var>, create a <span title="concept-task">task</span> to
<span>fire a simple event</span> that is cancelable named <code
title="event-appcache-cached">cached</code> at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span>, and add it to <var title="">task list</var>. The
default action of these events must be, if the user agent
<span>shows caching progress</span>, the display of some sort of
user interface indicating to the user that the application has
been cached and that they can now use it offline.</p>
<p>Otherwise, it is an <span
title="concept-appcache-upgrade">upgrade attempt</span>. For each
<span>cache host</span> associated with an <span>application
cache</span> in <var title="">cache group</var>, create a <span
title="concept-task">task</span> to <span>fire a simple
event</span> that is cancelable named <code
title="event-appcache-updateready">updateready</code> at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span>, and add it to <var title="">task list</var>. The
default action of these events must be, if the user agent
<span>shows caching progress</span>, the display of some sort of
user interface indicating to the user that a new version is
available and that they can activate it by reloading the page.</p>
</li>
<li><p>If appropriate, remove any user interface indicating that
an update for this cache is in progress.</p></li>
<li><p>Set the <span title="concept-appcache-status">update
status</span> of <var title="">cache group</var> to
<i>idle</i>.</p></li>
<li><p>For each <span title="concept-task">task</span> in <var
title="">task list</var>, <span title="queue a task">queue</span>
that task.</p></li>
</ol>
<p>The <dfn>cache failure steps</dfn> are as follows:</p>
<ol>
<li><p>Let <var title="">task list</var> be an empty list of <span
title="concept-task">tasks</span>.</p>
<li>
<p>For each entry in <var title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>, run the following further substeps. These steps
may be run in parallel for two or more entries at a time.</p>
<ol>
<li><p>Wait for the resource for this entry to have either
completely downloaded or failed.</p>
<li><p>Unassociate the <code>Document</code> for this entry from
its <span>application cache</span>, if it has one.</p></li>
<li><p>Create a <span title="concept-task">task</span> to
<span>fire a simple event</span> that is cancelable named <code
title="event-appcache-error">error</code> at the
<code>ApplicationCache</code> singleton of the
<code>Document</code> for this entry, if there still is one, and
add it to <var title="">task list</var>. The default action of
these events must be, if the user agent <span>shows caching
progress</span>, the display of some sort of user interface
indicating to the user that the user agent failed to save the
application for offline use.</p>
</ol>
</li>
<li><p>For each <span>cache host</span> still associated with an
<span>application cache</span> in <var title="">cache group</var>,
create a <span title="concept-task">task</span> to <span>fire a
simple event</span> that is cancelable named <code
title="event-appcache-error">error</code> at the
<code>ApplicationCache</code> singleton of the <span>cache
host</span>, and add it to <var title="">task list</var>. The
default action of these events must be, if the user agent
<span>shows caching progress</span>, the display of some sort of
user interface indicating to the user that the user agent failed to
save the application for offline use.</p></li>
<li><p>Empty <var title="">cache group</var>'s <span
title="concept-appcache-pending-masters">list of pending master
entries</span>.</p></li>
<li><p>If <var title="">cache group</var> has an <span>application
cache</span> whose <span
title="concept-appcache-completeness">completeness flag</span> is
<i>incomplete</i>, then discard that <span>application
cache</span>.</p>
<li><p>If appropriate, remove any user interface indicating that an
update for this cache is in progress.</p></li>
<li><p>Let the <span title="concept-appcache-status">status</span>
of <var title="">cache group</var> be <i>idle</i>.</p></li>
<li><p>If this was a <span title="concept-appcache-cache">cache
attempt</span>, discard <var title="">cache group</var>
altogether.</p>
<li><p>For each <span title="concept-task">task</span> in <var
title="">task list</var>, <span title="queue a task">queue</span>
that task.</p></li>
<li><p>Abort the <span>application cache download
process</span>.</p></li>
</ol>
<p>Attempts to <span>fetch</span> resources as part of the
<span>application cache download process</span> may be done with
cache-defeating semantics, to avoid problems with stale or
inconsistent intermediary caches.</p>
<hr>
<p>User agents may invoke the <span>application cache download
process</span>, in the background, for any <span>application
cache</span>, at any time (with no <span>cache host</span>). This
allows user agents to keep caches primed and to update caches even
before the user visits a site.</p>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <span>networking task
source</span>.</p>
<h4>The application cache selection algorithm</h4>
<p>When the <dfn title="concept-appcache-init">application cache
selection algorithm</dfn> algorithm is invoked with a
<code>Document</code> <var title="">document</var> and optionally a
manifest <span>URL</span> <var title="">manifest URL</var>, the user
agent must run the first applicable set of steps from the following
list:</p>
<dl class="switch">
<dt>If there is a <var title="">manifest URL</var>, and <var
title="">document</var> was loaded from an <span>application
cache</span>, and the URL of the <span
title="concept-appcache-manifest">manifest</span> of that cache's
<span>application cache group</span> is <em>not</em> the same as
<var title="">manifest URL</var></dt>
<dd>
<p>Mark the entry for the resource from which <var
title="">document</var> was taken in the <span>application
cache</span> from which it was loaded as <span
title="concept-appcache-foreign">foreign</span>.</p>
<p>Restart the current navigation from the top of the <span
title="navigate">navigation algorithm</span>, undoing any changes
that were made as part of the initial load (changes can be avoided
by ensuring that the step to <span>update the session history with
the new page</span> is only ever completed <em>after</em> this
<span title="concept-appcache-init">application cache selection
algorithm</span> is run, though this is not required).</p>
<p class="note">The navigation will not result in the same
resource being loaded, because "foreign" entries are never picked
during navigation.</p>
<p>User agents may notify the user of the inconsistency between
the cache manifest and the document's own metadata, to aid in
application development.</p>
</dd>
<dt>If <var title="">document</var> was loaded from an
<span>application cache</span><!--[redundant], and either there is
no <var title="">manifest URL</var>, or the URL of the <span
title="concept-appcache-manifest">manifest</span> of the cache's
<span>application cache group</span> is the same as <var
title="">manifest URL</var>--></dt>
<dd>
<p>Associate <var title="">document</var> with the
<span>application cache</span> from which it was loaded. Invoke
the <span>application cache download process</span> for that
<span>application cache</span>'s <span>application cache
group</span>, with <var title="">document</var> as the <span>cache
host</span>.</p>
</dd>
<dt>If <var title="">document</var> <!--[redundant] was not loaded
from an <span>application cache</span>, but it--> was loaded using
HTTP GET <span title="concept-http-equivalent-get">or
equivalent</span>, and, there is a <var title="">manifest
URL</var>, and <var title="">manifest URL</var> has the <span>same
origin</span> as <var title="">document</var></dt>
<dd>
<p>Invoke the <span>application cache download process</span> for
<var title="">manifest URL</var>, with <var
title="">document</var> as the <span>cache host</span> and with
the resource from which <var title="">document</var> was parsed as
the <span title="concept-appcache-master">master</span>
resource.</p>
</dd>
<dt>Otherwise</dt> <!-- not from cache and either no <var
title="">manifest URL</var>, or non-GET, or wrong-origin manifest -->
<dd>
<p>The <code>Document</code> is not associated with any
<span>application cache</span>.</p>
<p>If there was a <var title="">manifest URL</var>, the user agent
may report to the user that it was ignored, to aid in application
development.</p>
</dd>
</dl>
<h4 id="changesToNetworkingModel">Changes to the networking model</h4>
<p>When a <span>cache host</span> is associated with an
<span>application cache</span> whose <span
title="concept-appcache-completeness">completeness flag</span> is
<i>complete</i>, any and all loads for resources related to that
<span>cache host</span> other than those for <span title="child
browsing context">child browsing contexts</span> must go through the
following steps instead of immediately invoking the mechanisms
appropriate to that resource's scheme:</p>
<ol>
<li><p>If the resource is not to be fetched using the HTTP GET
mechanism <span title="concept-http-equivalent-get">or
equivalent</span>, or if its <span>URL</span> has a different <span
title="url-scheme"><scheme></span> component than the
<span>application cache</span>'s <span
title="concept-appcache-manifest">manifest</span>, then
<span>fetch</span> the resource normally and abort these
steps.</p></li>
<li><p>If the resource's URL is <span
title="concept-appcache-master">a master entry</span>, <span
title="concept-appcache-manifest">the manifest</span>, <span
title="concept-appcache-explicit">an explicit entry</span>, or
<span title="concept-appcache-fallback">a fallback entry</span> in
the <span>application cache</span>, then get the resource from the
cache (instead of fetching it), and abort these steps.</p></li>
<li><p>If there is an entry in the <span>application cache</span>'s
<span title="concept-appcache-onlinewhitelist">online
whitelist</span> that has the <span>same origin</span> as the
resource's URL and that is a <span>prefix match</span> for the
resource's URL, then <span>fetch</span> the resource normally and
abort these steps.</p></li>
<li>
<p>If the resource's URL has the <span>same origin</span> as the
manifest's URL, and there is a <span
title="concept-appcache-fallback-ns">fallback namespace</span>
<var title="">f</var> in the <span>application cache</span> that
is a <span>prefix match</span> for the resource's URL, then:</p>
<p><span>Fetch</span> the resource normally. If this results in a
redirect to a resource with another <span>origin</span>
(indicative of a captive portal), or a 4xx or 5xx status code
<span title="concept-http-equivalent-codes">or equivalent</span>,
or if there were network errors (but not if the user canceled the
download), then instead get, from the cache, the resource of the
<span title="concept-appcache-fallback">fallback entry</span>
corresponding to the <span
title="concept-appcache-fallback-ns">fallback namespace</span>
<var title="">f</var>. Abort these steps.</p>
</li>
<li><p>If the <span>application cache</span>'s <span
title="concept-appcache-onlinewhitelist-wildcard">online whitelist
wildcard flag</span> is <i title="">open</i>, then
<span>fetch</span> the resource normally and abort these
steps.</p></li>
<li><p>Fail the resource load.</p></li>
</ol>
<p class="note">The above algorithm ensures that so long as the
<span title="concept-appcache-onlinewhitelist-wildcard">online
whitelist wildcard flag</span> is <i title="">blocking</i>,
resources that are not present in the <span
title="concept-appcache-manifest">manifest</span> will always fail
to load (at least, after the <span>application cache</span> has been
primed the first time), making the testing of offline applications
simpler.</p>
</div>
<h4>Expiring application caches</h4>
<p>As a general rule, user agents should not expire application
caches, except on request from the user, or after having been left
unused for an extended period of time.</p>
<p>Application caches and cookies have similar implications with
respect to privacy (e.g. if the site can identify the user when
providing the cache, it can store data in the cache that can be used
for cookie resurrection). Implementors are therefore encouraged to
expose application caches in a manner related to HTTP cookies,
allowing caches to be expunged together with cookies and other
origin-specific data.</p>
<p class="example">For example, a user agent could have a "delete
site-specific data" feature that clears all cookies, application
caches, local storage, databases, etc, from an origin all at
once.</p>
<h4>Application cache API</h4>
<pre class="idl">interface <dfn>ApplicationCache</dfn> {
// <span title="concept-appcache-status">update status</span>
const unsigned short <span title="dom-appcache-UNCACHED">UNCACHED</span> = 0;
const unsigned short <span title="dom-appcache-IDLE">IDLE</span> = 1;
const unsigned short <span title="dom-appcache-CHECKING">CHECKING</span> = 2;
const unsigned short <span title="dom-appcache-DOWNLOADING">DOWNLOADING</span> = 3;
const unsigned short <span title="dom-appcache-UPDATEREADY">UPDATEREADY</span> = 4;
const unsigned short <span title="dom-appcache-OBSOLETE">OBSOLETE</span> = 5;
readonly attribute unsigned short <span title="dom-appcache-status">status</span>;
// updates
void <span title="dom-appcache-update">update</span>();
void <span title="dom-appcache-swapCache">swapCache</span>();
// events
attribute <span>Function</span> <span title="handler-appcache-onchecking">onchecking</span>;
attribute <span>Function</span> <span title="handler-appcache-onerror">onerror</span>;
attribute <span>Function</span> <span title="handler-appcache-onnoupdate">onnoupdate</span>;
attribute <span>Function</span> <span title="handler-appcache-ondownloading">ondownloading</span>;
attribute <span>Function</span> <span title="handler-appcache-onprogress">onprogress</span>;
attribute <span>Function</span> <span title="handler-appcache-onupdateready">onupdateready</span>;
attribute <span>Function</span> <span title="handler-appcache-oncached">oncached</span>;
attribute <span>Function</span> <span title="handler-appcache-onobsolete">onobsolete</span>;
};
<span>ApplicationCache</span> implements <span>EventTarget</span>;</pre>
<dl class="domintro">
<dt><var title="">cache</var> = <var title="">window</var> . <code title="dom-applicationCache">applicationCache</code></dt>
<dd>
<p>(In a window.) Returns the <code>ApplicationCache</code> object that applies to the <span>active document</span> of that <code>Window</code>.</p>
</dd>
<dt><var title="">cache</var> = <var title="">self</var> . <code title="dom-applicationCache">applicationCache</code></dt>
<dd>
<p>(In a shared worker.) Returns the <code>ApplicationCache</code> object that applies to the current shared worker.</p>
</dd>
<dt><var title="">cache</var> . <code title="dom-appcache-status">status</code></dt>
<dd>
<p>Returns the current status of the application cache, as given by the constants defined below.</p>
</dd>
<dt><var title="">cache</var> . <code title="dom-appcache-update">update</code>()</dt>
<dd>
<p>Invokes the <span>application cache download process</span>.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if there is no application cache to update.</p>
</dd>
<dt><var title="">cache</var> . <code title="dom-appcache-swapCache">swapCache</code>()</dt>
<dd>
<p>Switches to the most recent application cache, if there is a
newer one. If there isn't, throws an
<code>INVALID_STATE_ERR</code> exception.</p>
<p>This does not cause previously-loaded resources to be reloaded;
for example, images do not suddenly get reloaded and style sheets
and scripts do not get reparsed or reevaluated. The only change is
that subsequent requests for cached resources will obtain the
newer copies.</p>
</dd>
</dl>
<div class="impl">
<p>There is a one-to-one mapping from <span title="cache host">cache
hosts</span> to <code>ApplicationCache</code> objects. The <dfn
title="dom-applicationCache"><code>applicationCache</code></dfn>
attribute on <code>Window</code> objects must return the
<code>ApplicationCache</code> object associated with the
<code>Window</code> object's <span>active document</span>. The <dfn
title="dom-SharedWorkerGlobalScope-applicationCache"><code>applicationCache</code></dfn>
attribute on <code>SharedWorkerGlobalScope</code> objects must
return the <code>ApplicationCache</code> object associated with the
worker.
<!--END complete-->
<a href="#refsWEBWORKERS">[WEBWORKERS]</a>
<!--START complete-->
</p>
<p class="note">A <code>Window</code> or
<code>SharedWorkerGlobalScope</code> object has an associated
<code>ApplicationCache</code> object even if that <span>cache
host</span> has no actual <span>application cache</span>.</p>
<hr>
<p>The <dfn title="dom-appcache-status"><code>status</code></dfn>
attribute, on getting, must return the current state of the
<span>application cache</span> that the
<code>ApplicationCache</code> object's <span>cache host</span> is
associated with, if any. This must be the appropriate value from the
following list:</p>
</div>
<dl>
<dt><dfn title="dom-appcache-UNCACHED"><code>UNCACHED</code></dfn>
(numeric value 0)</dt>
<dd><p>The <code>ApplicationCache</code> object's <span>cache
host</span> is not associated with an <span>application
cache</span> at this time.</p></dd>
<dt><dfn title="dom-appcache-IDLE"><code>IDLE</code></dfn>
(numeric value 1)</dt>
<dd><p>The <code>ApplicationCache</code> object's <span>cache
host</span> is associated with an <span>application cache</span>
whose <span>application cache group</span>'s <span
title="concept-appcache-status">update status</span> is
<i>idle</i>, and that <span>application cache</span> is the <span
title="concept-appcache-newer">newest</span> cache in its
<span>application cache group</span>, and the <span>application
cache group</span> is not marked as <span
title="concept-appcache-obsolete">obsolete</span>.</p></dd>
<dt><dfn title="dom-appcache-CHECKING"><code>CHECKING</code></dfn>
(numeric value 2)</dt>
<dd><p>The <code>ApplicationCache</code> object's <span>cache
host</span> is associated with an <span>application cache</span>
whose <span>application cache group</span>'s <span
title="concept-appcache-status">update status</span> is
<i>checking</i>.</p></dd>
<dt><dfn title="dom-appcache-DOWNLOADING"><code>DOWNLOADING</code></dfn>
(numeric value 3)</dt>
<dd><p>The <code>ApplicationCache</code> object's <span>cache
host</span> is associated with an <span>application cache</span>
whose <span>application cache group</span>'s <span
title="concept-appcache-status">update status</span> is
<i>downloading</i>.</p></dd>
<dt><dfn title="dom-appcache-UPDATEREADY"><code>UPDATEREADY</code></dfn>
(numeric value 4)</dt>
<dd><p>The <code>ApplicationCache</code> object's <span>cache
host</span> is associated with an <span>application cache</span>
whose <span>application cache group</span>'s <span
title="concept-appcache-status">update status</span> is
<i>idle</i>, and whose <span>application cache group</span> is not
marked as <span title="concept-appcache-obsolete">obsolete</span>,
but that <span>application cache</span> is <em>not</em> the <span
title="concept-appcache-newer">newest</span> cache in its
group.</p></dd>
<dt><dfn title="dom-appcache-OBSOLETE"><code>OBSOLETE</code></dfn>
(numeric value 5)</dt>
<dd><p>The <code>ApplicationCache</code> object's <span>cache
host</span> is associated with an <span>application cache</span>
whose <span>application cache group</span> is marked as <span
title="concept-appcache-obsolete">obsolete</span>.</p></dd>
</dl>
<div class="impl">
<hr>
<p>If the <dfn
title="dom-appcache-update"><code>update()</code></dfn> method is
invoked, the user agent must invoke the <span>application cache
download process</span>, in the background, for the <span>application
cache</span> with which the <code>ApplicationCache</code> object's
<span>cache host</span> is associated, but without giving that
<span>cache host</span> to the algorithm. If there is no such
<span>application cache</span>, or if it is marked as <span
title="concept-appcache-obsolete">obsolete</span>, then the method
must raise an <code>INVALID_STATE_ERR</code> exception instead.</p>
<p>If the <dfn
title="dom-appcache-swapCache"><code>swapCache()</code></dfn> method
is invoked, the user agent must run the following steps:
<ol>
<li><p>Check that <code>ApplicationCache</code> object's
<span>cache host</span> is associated with an <span>application
cache</span>. If it is not, then raise an
<code>INVALID_STATE_ERR</code> exception and abort these
steps.</p></li>
<li><p>Let <var title="">cache</var> be the <span>application
cache</span> with which the <code>ApplicationCache</code> object's
<span>cache host</span> is associated. (By definition, this is the
same as the one that was found in the previous step.)</p></li>
<li><p>If <var title="">cache</var>'s <span>application cache
group</span> is marked as <span
title="concept-appcache-obsolete">obsolete</span>, then unassociate
the <code>ApplicationCache</code> object's <span>cache host</span>
from <var title="">cache</var> and abort these steps. (Resources
will now load from the network instead of the cache.)</p></li>
<li><p>Check that there is an application cache in the same
<span>application cache group</span> as <var title="">cache</var>
whose <span title="concept-appcache-completeness">completeness
flag</span> is <i>complete</i> and that is <span
title="concept-appcache-newer">newer</span> than <var
title="">cache</var>. If there is not, then raise an
<code>INVALID_STATE_ERR</code> exception and abort these
steps.</p></li>
<li><p>Let <var title="">new cache</var> be the <span
title="concept-appcache-newer">newest</span> <span>application
cache</span> in the same <span>application cache group</span> as
<var title="">cache</var> whose <span
title="concept-appcache-completeness">completeness flag</span> is
<i>complete</i>.</p></li>
<li><p>Unassociate the <code>ApplicationCache</code> object's
<span>cache host</span> from <var title="">cache</var> and instead
associate it with <var title="">new cache</var>.</p></li>
</ol>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as IDL attributes, by
all objects implementing the <code>ApplicationCache</code>
interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-appcache-onchecking"><code>onchecking</code></dfn> <td> <code title="event-appcache-checking">checking</code>
<tr><td><dfn title="handler-appcache-onerror"><code>onerror</code></dfn> <td> <code title="event-appcache-error">error</code>
<tr><td><dfn title="handler-appcache-onnoupdate"><code>onnoupdate</code></dfn> <td> <code title="event-appcache-noupdate">noupdate</code>
<tr><td><dfn title="handler-appcache-ondownloading"><code>ondownloading</code></dfn> <td> <code title="event-appcache-downloading">downloading</code>
<tr><td><dfn title="handler-appcache-onprogress"><code>onprogress</code></dfn> <td> <code title="event-appcache-progress">progress</code>
<tr><td><dfn title="handler-appcache-onupdateready"><code>onupdateready</code></dfn> <td> <code title="event-appcache-updateready">updateready</code>
<tr><td><dfn title="handler-appcache-oncached"><code>oncached</code></dfn> <td> <code title="event-appcache-cached">cached</code>
<tr><td><dfn title="handler-appcache-onobsolete"><code>onobsolete</code></dfn> <td> <code title="event-appcache-obsolete">obsolete</code>
</table>
</div>
<h4>Browser state</h4>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-navigator">navigator</code> . <code title="dom-navigator-onLine">onLine</code></dt>
<dd>
<p>Returns false if the user agent is definitely offline
(disconnected from the network). Returns true if the user agent
might be online.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-navigator-onLine"><code>navigator.onLine</code></dfn>
attribute must return false if the user agent will not contact the
network when the user follows links or when a script requests a
remote page (or knows that such an attempt would fail), and must
return true otherwise.</p>
<p>When the value that would be returned by the <code
title="dom-navigator-onLine">navigator.onLine</code> attribute of
the <code>Window</code> changes from true to false, the user agent
must <span>queue a task</span> to <span>fire a simple event</span>
named <dfn title="event-offline"><code>offline</code></dfn> at the
<code>Window</code> object.</p>
<p>On the other hand, when the value that would be returned by the
<code title="dom-navigator-onLine">navigator.onLine</code> attribute
of the <code>Window</code> changes from false to true, the user
agent must <span>queue a task</span> to <span>fire a simple
event</span> named <dfn
title="event-online"><code>online</code></dfn> at the
<code>Window</code> object.</p>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <span>networking task
source</span>.</p>
</div>
<p class="note">This attribute is inherently unreliable. A computer
can be connected to a network without having Internet access.</p>
<h3 id="history">Session history and navigation</h3>
<h4>The session history of browsing contexts</h4>
<p>The sequence of <code>Document</code>s in a <span>browsing
context</span> is its <dfn>session history</dfn>.</p>
<p><code>History</code> objects provide a representation of the
pages in the session history of <span title="browsing
context">browsing contexts</span>. Each <span>browsing
context</span>, including <span>nested browsing context</span>, has
a distinct session history.</p>
<p>Each <code>Document</code> object in a <span>browsing
context</span>'s <span>session history</span> is associated with a
unique instance of the <code>History</code> object, although they
all must model the same underlying <span>session history</span>.</p>
<div class="impl">
<p>The <dfn title="dom-history"><code>history</code></dfn> attribute
of the <code>Window</code> interface must return the object
implementing the <code>History</code> interface for that
<code>Window</code> object's <code>Document</code>.</p>
</div>
<p><code>History</code> objects represent their <span>browsing
context</span>'s session history as a flat list of <span
title="session history entry">session history entries</span>. Each
<dfn>session history entry</dfn> consists of either a
<span>URL</span> or a <span>state object</span>, or both<span
class="impl">, and may in addition have a title, a
<code>Document</code> object, form data, a scroll position, and
other information associated with it</span>.</p>
<div class="impl">
<p class="note">This does not imply that the user interface need be
linear. See the <a href="#history-notes">notes below</a>.</p>
</div>
<p class="note">Titles associated with <span title="session history
entry">session history entries</span> need not have any relation
with the current <code>title</code> of the
<code>Document</code>. The title of a <span>session history
entry</span> is intended to explain the state of the document at
that point, so that the user can navigate the document's
history.</p>
<p>URLs without associated <span title="state object">state
objects</span> are added to the session history as the user (or
script) navigates from page to page.</p>
<p>A <dfn>state object</dfn> is an object representing a user
interface state.</p>
<p>Pages can <span title="dom-history-pushState">add</span> <span
title="state object">state objects</span> between their entry in the
session history and the next ("forward") entry. These are then <span
title="event-popstate">returned to the script</span> when the user
(or script) goes back in the history, thus enabling authors to use
the "navigation" metaphor even in one-page applications.</p>
<p>At any point, one of the entries in the session history is the
<dfn>current entry</dfn>. This is the entry representing the
<span>active document</span> of the <span>browsing
context</span>. The <span>current entry</span> is usually an entry
for the <span title="dom-location-href">location</span> of the
<code>Document</code>. However, it can also be one of the entries
for <span title="state object">state objects</span> added to the
history by that document.</p>
<p>Entries that consist of <span title="state object">state
objects</span> share the same <code>Document</code> as the entry for
the page that was active when they were added.</p>
<p>Contiguous entries that differ just by fragment identifier also
share the same <code>Document</code>.</p>
<p class="note">All entries that share the same
<code>Document</code> (and that are therefore merely different
states of one particular document) are contiguous by definition.</p>
<div class="impl">
<p>User agents may <span title="discard a Document">discard</span>
the <code>Document</code> objects of entries other than the
<span>current entry</span> that are not referenced from any script,
reloading the pages afresh when the user or script navigates back to
such pages. This specification does not specify when user agents
should discard <code>Document</code> objects and when they should
cache them.</p>
<p>Entries that have had their <code>Document</code> objects
discarded must, for the purposes of the algorithms given below, act
as if they had not. When the user or script navigates back or
forwards to a page which has no in-memory DOM objects, any other
entries that shared the same <code>Document</code> object with it
must share the new object as well.</p>
</div>
<h4>The <code>History</code> interface</h4>
<pre class="idl">interface <dfn>History</dfn> {
readonly attribute long <span title="dom-history-length">length</span>;
void <span title="dom-history-go">go</span>(in optional long delta);
void <span title="dom-history-back">back</span>();
void <span title="dom-history-forward">forward</span>();
void <span title="dom-history-pushState">pushState</span>(in any data, in DOMString title, in optional DOMString url);
void <span title="dom-history-replaceState">replaceState</span>(in any data, in DOMString title, in optional DOMString url);
};</pre>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-history">history</code> . <code title="dom-history-length">length</code></dt>
<dd>
<p>Returns the number of entries in the <span>joint session history</span>.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-history">history</code> . <code title="dom-history-go">go</code>( [ <var title="">delta</var> ] )</dt>
<dd>
<p>Goes back or forward the specified number of steps in the <span>joint session history</span>.</p>
<p>A zero delta will reload the current page.</p>
<p>If the delta is out of range, does nothing.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-history">history</code> . <code title="dom-history-back">back</code>()</dt>
<dd>
<p>Goes back one step in the <span>joint session history</span>.</p>
<p>If there is no previous page, does nothing.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-history">history</code> . <code title="dom-history-forward">forward</code>()</dt>
<dd>
<p>Goes forward one step in the <span>joint session history</span>.</p>
<p>If there is no next page, does nothing.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-history">history</code> . <code title="dom-history-pushState">pushState</code>(<var title="">data</var>, <var title="">title</var> [, <var title="">url</var> ] )</dt>
<dd>
<p>Pushes the given data onto the session history, with the given title, and, if provided, the given URL.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-history">history</code> . <code title="dom-history-replaceState">replaceState</code>(<var title="">data</var>, <var title="">title</var> [, <var title="">url</var> ] )</dt>
<dd>
<p>Updates the current entry in the session histor to have the given data, title, and, if provided, URL.</p>
</dd>
</dl>
<p>The <dfn>joint session history</dfn> of a <code>History</code>
object is the union of all the <span title="session history">session
histories</span> of all <span title="browsing context">browsing
contexts</span> of all the <span>fully active</span>
<code>Document</code> objects that share the <code>History</code>
object's <span>top-level browsing context</span>, with all the
entries that are <span title="current entry">current entries</span>
in their respective <span title="session history">session
histories</span> removed except for the <span>current entry of the
joint session history</span>.</p>
<p>The <dfn>current entry of the joint session history</dfn> is the
entry that was the most recently became a <span>current entry</span>
in its <span>session history</span>.</p>
<p>Entries in the <span>joint session history</span> are ordered
chronologically by the time they were added to their respective
<span title="session history">session histories</span>. (Since all
these <span title="browsing context">browsing contexts</span> by
definition share an <span>event loop</span>, there is always a
well-defined sequential order in which their <span title="session
history">session histories</span> had their entries added.) Each
entry has an index; the earliest entry has index 0, and the
subsequent entries are numbered with consecutively increasing
integers (1, 2, 3, etc).</p>
<div class="impl">
<p>The <dfn title="dom-history-length"><code>length</code></dfn>
attribute of the <code>History</code> interface must return the
number of entries in the <span>joint session history</span>.</p>
<p>The actual entries are not accessible from script.</p>
<p>The <dfn title="dom-history-go"><code>go(<var
title="">delta</var>)</code></dfn> method causes the UA to run the
following steps:</p>
<ol>
<li><p>If the argument to the method was omitted or has the value
zero, then act as if the <code
title="dom-location-reload">location.reload()</code> method was
called instead, and abort these steps.</p>
<li><p>Let <var title="">delta</var> be the argument to the
method.</p></li>
<li><p>If the index of the <span>current entry of the joint session
history</span> plus <var title="">delta</var> is less than zero or
greater than or equal to the number of items in the <span>joint
session history</span>, then the user agent must do nothing.</p>
<li><p>Let <var title="">specified entry</var> be the entry in the
<span>joint session history</span> whose index is the sum of <var
title="">delta</var> and the index of the <span>current entry of
the joint session history</span>.</p></li>
<li><p>Let <var title="">specified browsing context</var> be the
<span>browsing context</span> of the <var title="">specified
entry</var>.</p></li>
<li><p><span>Traverse the history</span> of the <var
title="">specified browsing context</var> to the <var
title="">specified entry</var>.</p>
</ol>
<p>When the user navigates through a <span>browsing context</span>,
e.g. using a browser's back and forward buttons, the user agent must
translate this action into the equivalent invocations of the <code
title="dom-history-go">history.go(<var title="">delta</var>)</code>
method on the various affected <code
title="dom-window">window</code> objects.</p>
<p>Some of the other members of the <code>History</code> interface
are defined in terms of the <code title="dom-history-go">go()</code>
method, as follows:</p>
<table>
<tr>
<th>Member</th>
<th>Definition</th>
</tr>
<tr>
<td><dfn title="dom-history-back"><code>back()</code></dfn></td>
<td>Must do the same as <code title="dom-history-go">go(-1)</code></td>
</tr>
<tr>
<td><dfn title="dom-history-forward"><code>forward()</code></dfn></td>
<td>Must do the same as <code title="dom-history-go">go(1)</code></td>
</tr>
</table>
<hr>
<p>The <dfn title="dom-history-pushState"><code>pushState(<var
title="">data</var>, <var title="">title</var>, <var
title="">url</var>)</code></dfn> method adds a state object to the
history.</p>
<p>The <dfn title="dom-history-replaceState"><code>replaceState(<var
title="">data</var>, <var title="">title</var>, <var
title="">url</var>)</code></dfn> method updates the <span>current
entry</span> in the history to have a state object.</p>
<p>When either of these methods are invoked, the user agent must run
the following steps:</p>
<ol>
<li><p>Let <var title="">clone data</var> be a <span>structured
clone</span> of the specified <var title="">data</var>. If this
throws an exception, then rethrow that exception and abort these
steps.</p></li>
<li>
<p>If a third argument is specified, run these substeps:</p>
<ol>
<li><span title="resolve a url">Resolve</span> the value of the
third argument, relative to the <span>first script</span>'s <span
title="script's base URL">base URL</span>.</li>
<li>If that fails, raise a <code>SECURITY_ERR</code> exception
and abort these steps.</li>
<li>Compare the resulting <span>absolute URL</span> to <span>the
document's address</span>. If any part of these two <span
title="URL">URLs</span> differ other than the <span
title="url-path"><path></span>, <span
title="url-query"><query></span>, and <span
title="url-fragment"><fragment></span> components, then
raise a <code>SECURITY_ERR</code> exception and abort these
steps.</li>
</ol>
<p>For the purposes of the comparison in the above substeps, the
<span title="url-path"><path></span> and <span
title="url-query"><query></span> components can only be the
same if the URLs use a hierarchical <span
title="url-scheme"><scheme></span>.</p>
</li>
<li>
<p>If the method invoked was the <code
title="dom-history-pushState">pushState()</code> method:</p>
<ol>
<li><p>Remove from the <span>session history</span> any entries for
the <code>Document</code> from the entry after the <span>current
entry</span> up to the last entry in the session history that
references the same <code>Document</code> object, if any. If the
<span>current entry</span> is the last entry in the session
history, or if there are no entries after the <span>current
entry</span> that reference the same <code>Document</code> object,
then no entries are removed.</p></li>
<li><p>Add a state object entry to the session history, after the
<span>current entry</span>, with <var title="">cloned data</var> as
the state object, the given <var title="">title</var> as the title,
and, if the third argument is present, the <span>absolute
URL</span> that was found earlier in this algorithm as the
<span>URL</span> of the entry.</p></li>
<li><p>Update the <span>current entry</span> to be the this newly
added entry.</p></li>
</ol>
<p>Otherwise, if the method invoked was the <code
title="dom-history-replaceState">replaceState()</code> method:</p>
<ol>
<li><p>Update the <span>current entry</span> in the session
history so that <var title="">cloned data</var> is the entry's
new state object, the given <var title="">title</var> is the new
title, and, if the third argument is present, the <span>absolute
URL</span> that was found earlier in this algorithm is the
entry's new <span>URL</span>.</p></li>
</ol>
</li>
<li>
<p>If the third argument is present, set <span>the document's
current address</span> to the <span>absolute URL</span> that was
found earlier in this algorithm.</p>
<p class="note">Since this is neither a <span
title="navigate">navigation</span> of the <span>browsing
context</span> nor a <span title="traverse the history">history
traversal</span>, it does not cause a <code
title="event-hashchange">hashchange</code> event to be fired.</p>
</li>
</ol>
<p class="note">The <var title="">title</var> is purely
advisory. User agents might use the title in the user interface.</p>
<p>User agents may limit the number of state objects added to the
session history per page. If a page hits the UA-defined limit, user
agents must remove the entry immediately after the first entry for
that <code>Document</code> object in the session history after
having added the new entry. (Thus the state history acts as a FIFO
buffer for eviction, but as a LIFO buffer for navigation.)</p>
</div>
<div class="example">
<p>Consider a game where the user can navigate along a line, such
that the user is always at some coordinate, and such that the user
can bookmark the page corresponding to a particular coordinate, to
return to it later.</p>
<p>A static page implementing the x=5 position in such a game could
look like the following:</p>
<pre><!DOCTYPE HTML>
<!-- this is http://example.com/line?x=5 -->
<title>Line Game - 5</title>
<p>You are at coordinate 5 on the line.</p>
<p>
<a href="?x=6">Advance to 6</a> or
<a href="?x=4">retreat to 4</a>?
</p></pre>
<p>The problem with such a system is that each time the user
clicks, the whole page has to be reloaded. Here instead is another
way of doing it, using script:</p>
<pre><!DOCTYPE HTML>
<!-- this starts off as http://example.com/line?x=5 -->
<title>Line Game - 5</title>
<p>You are at coordinate <span id="coord">5</span> on the line.</p>
<p>
<a href="?x=6" onclick="go(1)">Advance to 6</a> or
<a href="?x=4" onclick="go(-1)">retreat to 4</a>?
</p>
<script>
var currentPage = 5; // prefilled by server
function go(d) {
history.pushState(currentPage, 'Line Game - ' + currentPage, '?x=' + currentPage);
setupPage(currentPage + d);
}
onpopstate = function(event) {
setupPage(event.state);
}
function setupPage(page) {
currentPage = page;
document.title = 'Line Game - ' + currentPage;
document.getElementById('coord').textContent = currentPage;
document.links[0].href = '?x=' + (currentPage+1);
document.links[0].textContent = 'Advance to ' + (currentPage+1);
document.links[1].href = '?x=' + (currentPage-1);
document.links[1].textContent = 'retreat to ' + (currentPage-1);
}
</script></pre>
<p>In systems without script, this still works like the previous
example. However, users that <em>do</em> have script support can
now navigate much faster, since there is no network access for the
same experience. Furthermore, contrary to the experience the user
would have with just a naïve script-based approach,
bookmarking and navigating the session history still work.</p>
<p>In the example above, the <var title="">data</var> argument to
the <code title="dom-history-pushState">pushState()</code> method
is the same information as would be sent to the server, but in a
more convenient form, so that the script doesn't have to parse the
URL each time the user navigates.</p>
</div>
<div class="example">
<p>Applications might not use the same title for a <span>session
history entry</span> as the value of the document's
<code>title</code> element at that time. For example, here is a
simple page that shows a block in the <code>title</code> element.
Clearly, when navigating backwards to a previous state the user
does not go back in time, and therefore it would be inappropriate
to put the time in the session history title.</p>
<pre><!DOCTYPE HTML>
<TITLE>Line</TITLE>
<SCRIPT>
setInterval(function () { document.title = 'Line - ' + new Date(); }, 1000);
var i = 1;
function inc() {
set(i+1);
history.pushState(i, 'Line - ' + i);
}
function set(newI) {
i = newI;
document.forms.F.I.value = newI;
}
</SCRIPT>
<BODY ONPOPSTATE="recover(event.state)">
<FORM NAME=F>
State: <OUTPUT NAME=I>1</OUTPUT> <INPUT VALUE="Increment" TYPE=BUTTON ONCLICK="inc()">
</FORM></pre>
</div>
<h4><dfn title="activate the state object">Activating state object entries</dfn></h4>
<div class="impl">
<p>When an entry in the session history is activated (which happens
during <span title="traverse the history">session history
traversal</span>), the user agent must run the following steps:</p>
<ol><!-- only called for the first entry of a Document set and for
state object entries, not for frag id change entries -->
<li><p>If the entry is a <span>state object</span> entry, let <var
title="">state</var> be a <span>structured clone</span> of that
state object. Otherwise, let <var title="">state</var> be
null.</p></li>
<li>
<p>Run the appropriate steps according to the conditions
described:</p>
<dl class="switch">
<dt>If the <span>current document readiness</span> is set to the
string "complete"</dt>
<dd><p>Synchronously fire a <dfn
title="event-popstate"><code>popstate</code></dfn> event on the
<code>Window</code> object of the <code>Document</code>, using
the <code>PopStateEvent</code> interface, with the <code
title="dom-PopStateEvent-state">state</code> attribute set to the
value of <var title="">state</var>. This event must bubble but
not be cancelable and has no default action.</p></dd>
<dt>Otherwise</dt>
<dd><p>Let the <code>Document</code>'s <dfn>pending state
object</dfn> be <var title="">state</var>. (If there was already
a <span>pending state object</span>, the previous one is
discarded.)</p>
<p class="note">The event will then be fired just after the <code
title="event-load">load</code> event.</p></dd>
</dl>
</li>
</ol>
<p>The <span>pending state object</span> must be initially null.</p>
<hr>
</div>
<pre class="idl">interface <dfn>PopStateEvent</dfn> : Event {
readonly attribute any <span title="dom-PopStateEvent-state">state</span>;
void <span title="dom-PopStateEvent-initPopStateEvent">initPopStateEvent</span>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any stateArg);
};</pre>
<dl class="domintro">
<dt><var title="">event</var> . <code title="dom-PopStateEvent-state">state</code></dt>
<dd>
<p>Returns the information that was provided to <code
title="dom-history-pushState">pushState()</code> or <code
title="dom-history-replaceState">replaceState()</code>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-PopStateEvent-initPopStateEvent"><code>initPopStateEvent()</code></dfn>
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. <a
href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p>The <dfn title="dom-PopStateEvent-state"><code>state</code></dfn>
attribute represents the context information for the event, or null,
if the state represented is the initial state of the
<code>Document</code>.</p>
</div>
<h4>The <code>Location</code> interface</h4>
<p>Each <code>Document</code> object in a <span>browsing
context</span>'s session history is associated with a unique
instance of a <code>Location</code> object.</p>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-location">location</code> [ = <var title="">value</var> ]</dt>
<dt><var title="">window</var> . <code title="dom-location">location</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns a <code>Location</code> object with the current page's location.</p>
<p>Can be set, to navigate to another page.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-document-location"><code>location</code></dfn> attribute
of the <code>HTMLDocument</code> interface must return the
<code>Location</code> object for that <code>Document</code> object,
if it is in a <span>browsing context</span>, and null otherwise.</p>
<p>The <dfn title="dom-location"><code>location</code></dfn>
attribute of the <code>Window</code> interface must return the
<code>Location</code> object for that <code>Window</code> object's
<code>Document</code>.</p>
</div>
<p><code>Location</code> objects provide a representation of <span
title="the document's current address">their document's current
address</span>, and allow the <span>current entry</span> of the
<span>browsing context</span>'s session history to be changed, by
adding or replacing entries in the <code
title="dom-history">history</code> object.</p>
<pre class="idl">interface <dfn>Location</dfn> {
stringifier readonly attribute DOMString <span title="dom-location-href">href</span>;
void <span title="dom-location-assign">assign</span>(in DOMString url);
void <span title="dom-location-replace">replace</span>(in DOMString url);
void <span title="dom-location-reload">reload</span>();
// <span>URL decomposition IDL attributes</span> <!-- blame brendan for these "innovative" names -->
attribute DOMString <span title="dom-location-protocol">protocol</span>;
attribute DOMString <span title="dom-location-host">host</span>;
attribute DOMString <span title="dom-location-hostname">hostname</span>;
attribute DOMString <span title="dom-location-port">port</span>;
attribute DOMString <span title="dom-location-pathname">pathname</span>;
attribute DOMString <span title="dom-location-search">search</span>;
attribute DOMString <span title="dom-location-hash">hash</span>;
// resolving relative URLs
DOMString <span title="dom-location-resolveURL">resolveURL</span>(in DOMString url);
};</pre>
<dl class="domintro">
<dt><var title="">location</var> . <code title="dom-location-href">href</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current page's location.</p>
<p>Can be set, to navigate to another page.</p>
</dd>
<dt><var title="">location</var> . <code title="dom-location-assign">assign</code>(<var title="">url</var>)</dt>
<dd>
<p>Navigates to the given page.</p>
</dd>
<dt><var title="">location</var> . <code title="dom-location-replace">replace</code>(<var title="">url</var>)</dt>
<dd>
<p>Removes the current page from the session history and navigates to the given page.</p>
</dd>
<dt><var title="">location</var> . <code title="dom-location-reload">reload</code>()</dt>
<dd>
<p>Reloads the current page.</p>
</dd>
<dt><var title="">url</var> = <var title="">location</var> . <code title="dom-location-resolveURL">resolveURL</code>(<var title="">url</var>)</dt>
<dd>
<p>Resolves the given relative URL to an absolute URL.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-location-href"><code>href</code></dfn>
attribute must return <span title="the document's current
address">the current address</span> of the associated
<code>Document</code> object, as an <span>absolute URL</span>.</p>
<p>On setting, <!-- READ ME WHEN EDITING THIS: Mozilla does this,
but IE doesn't. What should we do?: the behavior depends on the
context in which the script that set the attribute is running. If
the script ran as the direct result of the execution of a
<code>script</code> element in the document represented by the
<code>Location</code> object's associated <code>Document</code>
object, then the user agent must act as if the <code
title="dom-location-replace">replace()</code> method had been called
with the new value as its argument. Otherwise,--> the user agent
must act as if the <code title="dom-location-assign">assign()</code>
method had been called with the new value as its argument.</p><!--
v2: may wish to allow replace instead as a UI improvement -->
<!-- we could change the magic .location setter to simply refer
straight to assign(), so we don't have two levels of indirection -->
<p>When the <dfn title="dom-location-assign"><code>assign(<var
title="">url</var>)</code></dfn> method is invoked, the UA must
<span title="resolve a url">resolve</span> the argument, relative to
the <span>first script</span>'s <span title="script's base URL">base
URL</span>, and if that is successful, must <span>navigate</span>
the <span>browsing context</span> to the specified <var
title="">url</var>. If the <span>browsing context</span>'s
<span>session history</span> contains only one
<code>Document</code>, and that was the <code>about:blank</code>
<code>Document</code> created when the <span>browsing context</span>
was created, then the navigation must be done with
<span>replacement enabled</span>.</p> <!-- READ ME WHEN EDITING
THIS: IE and Firefox only seem to treat it that way if the DOM is
still a virgin DOM; Safari doesn't check that. Thus this might need
changing if testing shows the IE/Firefox behaviour is required
here. -->
<p>When the <dfn title="dom-location-replace"><code>replace(<var
title="">url</var>)</code></dfn> method is invoked, the UA must
<span title="resolve a url">resolve</span> the argument, relative to
the <span>first script</span>'s <span title="script's base URL">base
URL</span>, and if that is successful, <span>navigate</span> the
<span>browsing context</span> to the specified <var
title="">url</var> with <span>replacement enabled</span>.</p>
<p>Navigation for the <code
title="dom-location-assign">assign()</code> and <code
title="dom-location-replace">replace()</code> methods must be done
with the <span title="script's browsing context">browsing
context</span> of the script that invoked the method as the
<span>source browsing context</span>.</p>
<p>If the <span title="resolve a url">resolving</span> step of the
<code title="dom-location-assign">assign()</code> and <code
title="dom-location-replace">replace()</code> methods is not
successful, then the user agent must instead throw a
<code>SYNTAX_ERR</code> exception.</p>
<p>When the <dfn
title="dom-location-reload"><code>reload()</code></dfn> method is
invoked, the user agent must run the appropriate steps from the
following list:</p>
<dl class="switch">
<dt>If the currently executing <span
title="concept-task">task</span> is the dispatch of a <code
title="event-resize">resize</code> event in response to the user
resizing the <span>browsing context</span></dt>
<dd><p>Repaint the <span>browsing context</span> and abort these
steps.</p></dd> <!-- this theoretically would have no effect but in
practice can be useful to work around rendering bugs. -->
<dt>Otherwise</dt>
<dd><p><span>Navigate</span> the <span>browsing context</span> to
<span>the document's current address</span> with
<span>replacement enabled</span>. The <span>source browsing
context</span> must be the <span>browsing context</span> being
navigated.</p></dd> <!-- it appears that document.reload() always
uses GET and does not, e.g., re-POST. -->
<!-- http://software.hixie.ch/utilities/js/live-dom-viewer/saved/141 -->
</dl>
<p>When a user requests that the current page be reloaded through a
user interface element, the user agent should <span>navigate</span>
the <span>browsing context</span> to the same resource as
<code>Document</code>, with <span>replacement enabled</span>. In the
case of non-idempotent methods (e.g. HTTP POST), the user agent
should prompt the user to confirm the operation first, since
otherwise transactions (e.g. purchases or database modifications)
could be repeated. User agents may allow the user to explicitly
override any caches when reloading.</p>
</div>
<p>The <code>Location</code> interface also has the complement of
<span>URL decomposition IDL attributes</span>, <dfn
title="dom-location-protocol"><code>protocol</code></dfn>, <dfn
title="dom-location-host"><code>host</code></dfn>, <dfn
title="dom-location-port"><code>port</code></dfn>, <dfn
title="dom-location-hostname"><code>hostname</code></dfn>, <dfn
title="dom-location-pathname"><code>pathname</code></dfn>, <dfn
title="dom-location-search"><code>search</code></dfn>, and <dfn
title="dom-location-hash"><code>hash</code></dfn>. <span
class="impl">These must follow the rules given for URL decomposition IDL
attributes, with the <span title="concept-uda-input">input</span>
being <span title="the document's current address">the current
address</span> of the associated <code>Document</code> object, as an
<span>absolute URL</span> (same as the <code
title="dom-location-href">href</code> attribute), and the <span
title="concept-uda-setter">common setter action</span> being the
same as setting the <code title="dom-location-href">href</code>
attribute to the new output value.</span></p>
<div class="impl">
<hr>
<p>The <dfn title="dom-location-resolveURL"><code>resolveURL(<var
title="">url</var>)</code></dfn> method must <span title="resolve a
url">resolve</span> its <var title="">url</var> argument, relative
to the <span>first script</span>'s <span title="script's base
URL">base URL</span>, and if that succeeds, return the resulting
<span>absolute URL</span>. If it fails, it must throw a
<code>SYNTAX_ERR</code> exception instead.</p>
</div>
<div class="impl">
<h5>Security</h5>
<p>User agents must raise a <code>SECURITY_ERR</code> exception whenever
any of the members of a <code>Location</code> object are accessed by
scripts whose <span>effective script origin</span> is not the <span
title="same origin">same</span> as the <code>Location</code>
object's associated <code>Document</code>'s <span>effective script
origin</span>, with the following exceptions:</p>
<ul>
<li>The <code title="dom-location-href">href</code> setter, if the
script is running in a <span>browsing context</span> that is
<span>allowed to navigate</span> the browsing context with which
the <code>Location</code> object is associated
<li>The <code title="dom-location-replace">replace()</code> method,
if the script is running in a <span>browsing context</span> that is
<span>allowed to navigate</span> the browsing context with which
the <code>Location</code> object is associated
</ul>
</div>
<div class="impl">
<h4 id="history-notes">Implementation notes for session history</h4>
<!-- don't change the ID without updating multiple internal links -->
<p><i>This section is non-normative.</i></p>
<p>The <code>History</code> interface is not meant to place
restrictions on how implementations represent the session history to
the user.</p>
<p>For example, session history could be implemented in a tree-like
manner, with each page having multiple "forward" pages. This
specification doesn't define how the linear list of pages in the
<code title="dom-history">history</code> object are derived from the
actual session history as seen from the user's perspective.</p>
<p>Similarly, a page containing two <code>iframe</code>s has a <code
title="dom-history">history</code> object distinct from the
<code>iframe</code>s' <code title="dom-history">history</code>
objects, despite the fact that typical Web browsers present the user
with just one "Back" button, with a session history that interleaves
the navigation of the two inner frames and the outer page.</p>
<p><strong>Security</strong>: It is suggested that to avoid letting
a page "hijack" the history navigation facilities of a UA by abusing
<code title="dom-history-pushState">pushState()</code>, the UA
provide the user with a way to jump back to the previous page
(rather than just going back to the previous state). For example,
the back button could have a drop down showing just the pages in the
session history, and not showing any of the states. Similarly, an
aural browser could have two "back" commands, one that goes back to
the previous state, and one that jumps straight back to the previous
page.</p>
<p>In addition, a user agent could ignore calls to <code
title="dom-history-pushState">pushState()</code> that are invoked on
a timer, or from event listeners that are not triggered in response
to a clear user action, or that are invoked in rapid succession.</p>
</div>
<h3>Browsing the Web</h3>
<div class="impl">
<h4>Navigating across documents</h4>
<p>Certain actions cause the <span>browsing context</span> to
<i>navigate</i> to a new resource. Navigation always involves
<dfn>source browsing context</dfn>, which is the browsing context
which was responsible for starting the navigation.</p>
<p class="example">For example, <span title="following
hyperlinks">following a hyperlink</span>, <span
title="concept-form-submit">form submission</span>, and the <code
title="dom-open">window.open()</code> and <code
title="dom-location-assign">location.assign()</code> methods can all
cause a browsing context to navigate.</p>
<p>A user agent may provide various ways for the user to explicitly
cause a browsing context to navigate, in addition to those defined
in this specification.</p>
<p>When a browsing context is <dfn title="navigate">navigated</dfn>
to a new resource, the user agent must run the following steps:</p>
<ol>
<li><p>Release the <span>storage mutex</span>.</p></li>
<li id="sandboxLinks"><p>If the <span>source browsing
context</span> is not the same as the <span>browsing context</span>
being navigated, and the <span>source browsing context</span> is
not one of the <span title="ancestor browsing context">ancestor
browsing contexts</span> of the <span>browsing context</span> being
navigated, and the <span>source browsing context</span> has its
<span>sandboxed navigation browsing context flag</span> set, then
abort these steps. The user agent may offer to open the new
resource in a new <span>top-level browsing context</span> or in the
<span>top-level browsing context</span> of the <span>source
browsing context</span>, at the user's option, in which case the
user agent must <span>navigate</span> that designated
<span>top-level browsing context</span> to the new resource as if
the user had requested it independently.</p></li>
<li id="seamlessLinks"><p>If the <span>source browsing
context</span> is the same as the <span>browsing context</span>
being navigated, and this browsing context has its <span>seamless
browsing context flag</span> set, then find the nearest
<span>ancestor browsing context</span> that does not have its
<span>seamless browsing context flag</span> set, and continue these
steps as if <em>that</em> <span>browsing context</span> was the one
that was going to be <span title="navigate">navigated</span>
instead.</p></li>
<li><p>If there is a preexisting attempt to navigate the
<span>browsing context</span>, and the <span>source browsing
context</span> is the same as the <span>browsing context</span>
being navigated, and that attempt is currently
running the <span>unload a document</span> algorithm, and the
<span>origin</span> of the <span>URL</span> of the resource being
loaded in that navigation is not the <span>same origin</span> as
the <span>origin</span> of the <span>URL</span> of the resource
being loaded in <em>this</em> navigation, then abort these steps
without affecting the preexisting attempt to navigate the
<span>browsing context</span>.</p></li>
<!-- http://www.hixie.ch/tests/adhoc/html/navigation/unload/ -->
<li><p>If there is a preexisting attempt to navigate the
<span>browsing context</span>, and either that attempt has not yet
<span title="concept-navigate-mature">matured</span> (i.e. it has
not passed the point of making its <code>Document</code> the
<span>active document</span>), or that navigation's resource is not
to be fetched using HTTP GET <span
title="concept-http-equivalent-get">or equivalent</span>, or its
resource's <span>absolute URL</span> differs from this attempt's by
more than the presence, absence, or value of the <span
title="url-fragment"><fragment></span> component, then cancel
that preexisting attempt to navigate the <span>browsing
context</span>.</p></li>
<li id="navigate-fragid-step"><p><i>Fragment identifiers</i>: If
the <span>absolute URL</span> of the new resource is the same as
the <span title="the document's address">address</span> of the
<span>active document</span> of the <span>browsing context</span>
being navigated, ignoring any <span
title="url-fragment"><fragment></span> components of those
<span title="URL">URLs</span>, and the new resource is to be
fetched using HTTP GET <span title="concept-http-equivalent-get">or
equivalent</span>, and the <span>absolute URL</span> of the new
resource has a <span title="url-fragment"><fragment></span>
component (even if it is empty), then <span
title="navigate-fragid">navigate to that fragment identifier</span>
and abort these steps.</p></li>
<li><p>Cancel <em>any</em> preexisting attempt to navigate the
<span>browsing context</span>.</p></li>
<li><p>If the new resource is to be handled using a mechanism that
does not affect the browsing context, e.g. ignoring the navigation
request altogether because the specified scheme is not one of the
supported protocols, then abort these steps and proceed with that
mechanism instead.</p></li>
<li><p><span title="prompt to unload a document">Prompt to
unload</span> the <code>Document</code> object. If the user
<span>refused to allow the document to be unloaded</span>, then
these steps must be aborted.</p></li>
<li>
<p>If the new resource is to be handled by displaying some sort of
inline content, e.g. an error message because the specified scheme
is not one of the supported protocols, or an inline prompt to
allow the user to select <span
title="dom-navigator-registerProtocolHandler">a registered
handler</span> for the given scheme, then <span
title="navigate-ua-inline">display the inline content</span> and
abort these steps.</p>
<p class="note">In the case of a registered handler being used,
the algorithm will be reinvoked with a new URL to handle the
request.</p>
</li>
<li>
<p>If the new resource is to be fetched using HTTP GET <span
title="concept-http-equivalent-get">or equivalent</span>, then
check if there are any <span title="relevant application
cache">relevant application caches</span> that are identified by a
URL with the <span>same origin</span> as the URL in question, and
that have this URL as one of their entries, excluding entries
marked as <span
title="concept-appcache-foreign">foreign</span>. If so, then the
user agent must then get the resource from the <span
title="concept-appcache-selection">most appropriate application
cache</span> of those that match.</p>
<p class="example">For example, imagine an HTML page with an
associated application cache displaying an image and a form, where
the image is also used by several other application caches. If the
user right-clicks on the image and chooses "View Image", then the
user agent could decide to show the image from any of those
caches, but it is likely that the most useful cache for the user
would be the one that was used for the aforementioned HTML
page. On the other hand, if the user submits the form, and the
form does a POST submission, then the user agent will not use an
application cache at all; the submission will be made to the
network.</p>
<p>Otherwise, <span>fetch</span> the new resource, if it has not
already been obtained<!-- it's obtained by <object>, for instance
-->.</p>
<p>If the resource is being fetched using a method other than one
<span title="concept-http-equivalent-get">equivalent to</span>
HTTP's GET<!-- or HEAD (but that can't happen) -->, or, if the
<span title="navigate">navigation algorithm</span> was invoked as
a result of the <span title="concept-form-submit">form submission
algorithm</span>, then the <span title="fetch">fetching
algorithm</span> must be invoked from the <span>origin</span> of
the <span>active document</span> of the <span>source browsing
context</span>, if any.</p> <!-- potentially http-origin privacy
sensitive -->
<p>If the <span>browsing context</span> being navigated is a
<span>child browsing context</span> for an <code>iframe</code> or
<code>object</code> element, then the <span title="fetch">fetching
algorithm</span> must be invoked from the <code>iframe</code> or
<code>object</code> element's <span>browsing context scope
origin</span>, if it has one.</p> <!-- potentially http-origin
privacy sensitive -->
</li>
<li>
<p>If fetching the resource is synchronous (i.e. for
<code>about:blank</code>), then this must be synchronous, but if
fetching the resource depends on external resources, as it usually
does for URLs that use HTTP or other networking protocols, then at
this point the user agents must yield to whatever <span
title="concept-script">script</span> invoked the navigation steps,
if they were invoked by script.</p>
</li>
<li>
<p>If fetching the resource results in a redirect, return to <a
href="#navigate-fragid-step">the step labeled "fragment
identifiers"</a> with the new resource.</p>
</li>
<li><p>Wait for one or more bytes to be available or for the user
agent to establish that the resource in question is empty. During
this time, the user agent may allow the user to cancel this
navigation attempt or start other navigation attempts.</p></li>
<li>
<p>If the resource was not fetched from an <span>application
cache</span>, and was to be fetched using HTTP GET <span
title="concept-http-equivalent-get">or equivalent</span>, and its
URL <span title="concept-appcache-matches-fallback">matches the
fallback namespace</span> of one or more <span title="relevant
application cache">relevant application caches</span>, and the
user didn't cancel the navigation attempt during the previous
step, and the navigation attempt failed (e.g. the server returned
a 4xx or 5xx status code <span
title="concept-http-equivalent-codes">or equivalent</span>, or
there was a DNS error), then:</p> <!-- note that a redirect can
never reach this point as it is handled earlier, meaning that a
captive portal captures URLs in fallback namespaces and you can't
ever get to the fallback file of a resource if you have a captive
portal -->
<p>Let <var title="">candidate</var> be the <span
title="concept-appcache-fallback">fallback resource</span>
specified for the <span
title="concept-appcache-fallback-ns">fallback namespace</span> in
question. If multiple application caches match, the user agent
must use the fallback of the <span
title="concept-appcache-selection">most appropriate application
cache</span> of those that match.</p>
<p>If <var title="">candidate</var> is not marked as <span
title="concept-appcache-foreign">foreign</span>, then the user
agent must discard the failed load and instead continue along
these steps using <var title="">candidate</var> as the
resource. <span>The document's address</span>, if appropriate,
will still be the originally requested URL, not the fallback URL,
but the user agent may indicate to the user that the original page
load failed, that the page used was a fallback resource, and what
the URL of the fallback resource actually is.</p>
</li>
<li><p>If the document's out-of-band metadata (e.g. HTTP headers),
not counting any <span title="Content-Type">type information</span>
(such as the Content-Type HTTP header), requires some sort of
processing that will not affect the browsing context, then perform
that processing and abort these steps.</p>
<div class="note">
<p>Such processing might be triggered by, amongst other things, the
following:</p>
<ul class="brief">
<li>HTTP status codes (e.g. 204 No Content or 205 Reset Content)</li>
<li>HTTP Content-Disposition headers</li>
<li>Network errors</li>
</ul>
</div>
<!-- theorectically, HTTP 205 processing would occur here,
resetting all forms with no other effect. However, it seems nobody
actually wants to use this ability, so requiring it here seems
like unnecessary work. -->
<p>HTTP 401 responses that do not include a challenge recognized
by the user agent must be processed as if they had no challenge,
e.g. rendering the entity body as if the response had been 200
OK.</p>
<p>User agents may show the entity body of an HTTP 401 response
even when the response do include a recognized challenge, with the
option to login being included in a non-modal fashion, to enable
the information provided by the server to be used by the user
before authenticating. Similarly, user agents should allow the
user to authenticate (in a non-modal fashion) against
authentication challenges included in other responses such as HTTP
200 OK responses, effectively allowing resources to present HTTP
login forms without requiring their use.</p>
</li>
<li><p>Let <var title="">type</var> be <span title="Content-Type
sniffing">the sniffed type of the resource</span>.</p></li>
<li><p>If the user agent has been configured to process resources
of the given <var title="">type</var> using some mechanism other
than rendering the content in a <span>browsing context</span>, then
skip this step. Otherwise, if the <var title="">type</var> is one
of the following types, jump to the appropriate entry in the
following list, and process the resource as described there:</p>
<dl class="switch">
<dt>"<code>text/html</code>"</dt>
<dd>Follow the steps given in the <span
title="navigate-html">HTML document</span> section, and abort
these steps.</dd>
<!-- an <span>XML MIME type</span> -->
<dt>Any type ending in "<code title="">+xml</code>"</dt> <!-- no need to say that the _subtype_ ends in "+xml" so long as the "sniffed type" algorithm continues to drop parameters -->
<dt>"<code>application/xml</code>"</dt>
<dt>"<code>text/xml</code>"</dt>
<dd>Follow the steps given in the <span title="navigate-xml">XML
document</span> section. If that section determines that the
content is <em>not</em> to be displayed as a generic XML
document, then proceed to the next step in this overall set of
steps. Otherwise, abort these steps.</dd>
<dt>"<code>text/plain</code>"</dt>
<dd>Follow the steps given in the <span
title="navigate-text">plain text file</span> section, and abort
these steps.</dd>
<dt>A supported image type</dt>
<dd>Follow the steps given in the <span
title="navigate-image">image</span> section, and abort these
steps.</dd>
<dt>A type that will use an external application to render the
content in the <span>browsing context</span></dt>
<dd>Follow the steps given in the <span
title="navigate-plugin">plugin</span> section, and abort these
steps.</dd>
</dl>
<p><dfn title="set the document's address">Setting the document's
address</dfn>: If there is no <dfn>override URL</dfn>, then any
<code>Document</code> created by these steps must have its <span
title="the document's address">address</span> set to the
<span>URL</span> that was originally to be <span
title="fetch">fetched</span>, ignoring any other data that was
used to obtain the resource (e.g. the entity body in the case of a
POST submission is not part of <span>the document's
address</span>, nor is the URL of the fallback resource in the
case of the original load having failed and that URL having been
found to match a <span
title="concept-appcache-fallback-ns">fallback
namespace</span>). However, if there <em>is</em> an <span>override
URL</span>, then any <code>Document</code> created by these steps
must have its <span title="the document's address">address</span>
set to that <span>URL</span> instead.</p>
<p class="note">An <span title="override URL">override URL</span>
is set when <span title="concept-js-deref">dereferencing a
<code>javascript:</code> URL</span>.</p>
<p><dfn title="create a Document object">Creating a new
<code>Document</code> object</dfn>: When a <code>Document</code>
is created as part of the above steps, a new set of <span
title="view">views</span> along with the associated
<code>Window</code> object must be created and associated with the
<code>Document</code>, with one exception: if the <span>browsing
context</span>'s only entry in its <span>session history</span> is
the <code>about:blank</code> <code>Document</code> that was added
when the <span>browsing context</span> was created, and navigation
is occurring with <span>replacement enabled</span>, and that
<code>Document</code> has the <span>same origin</span> as the new
<code>Document</code>, then the <code>Window</code> object and
associated <span title="view">views</span> of that
<code>Document</code> must be used instead, and the <code
title="dom-document">document</code> attribute of the
<code>AbstractView</code> objects of those <span
title="view">views</span> must be changed to point to the new
<code>Document</code> instead.</p>
</li>
<li id="navigate-non-Document">
<p><i>Non-document content</i>: If, given <var
title="">type</var>, the new resource is to be handled by
displaying some sort of inline content, e.g. a native rendering of
the content, an error message because the specified type is not
supported, or an inline prompt to allow the user to select <span
title="dom-navigator-registerContentHandler">a registered
handler</span> for the given type, then <span
title="navigate-ua-inline">display the inline content</span> and
abort these steps.</p>
<p class="note">In the case of a registered handler being used,
the algorithm will be reinvoked with a new URL to handle the
request.</p>
</li>
<li><p>Otherwise, the document's <var title="">type</var> is such
that the resource will not affect the browsing context,
e.g. because the resource is to be handed to an external
application. Process the resource appropriately.</p>
</ol>
<hr>
<p>Some of the sections below, to which the above algorithm defers
in certain cases, require the user agent to <dfn>update the session
history with the new page</dfn>. When a user agent is required to do
this, it must <span>queue a task</span> to run the following
steps:</p>
<ol>
<li><p><span title="unload a document">Unload</span> the
<code>Document</code> object of the <span>current entry</span>,
with the <var title="">recycle</var> parameter set to
false.</p></li>
<li>
<dl>
<dt>If the navigation was initiated for <dfn>entry update</dfn> of
an entry</dt>
<dd>
<ol>
<li><p>Replace the entry being updated with a new entry
representing the new resource and its <code>Document</code>
object and related state. The user agent may propagate state from
the old entry to the new entry (e.g. scroll position).</p></li>
<li><p><span>Traverse the history</span> to the new
entry.</p></li>
</ol>
</dd>
<dt>Otherwise</dt>
<dd>
<ol>
<li><p>Remove all the entries after the <span>current
entry</span> in the <span>browsing context</span>'s
<code>Document</code> object's <code>History</code> object.</p>
<p class="note">This <a href="#history-notes">doesn't
necessarily have to affect</a> the user agent's user
interface.</p> </li>
<li><p>Append a new entry at the end of the <code>History</code>
object representing the new resource and its
<code>Document</code> object and related state.</p></li>
<li><p><span>Traverse the history</span> to the new entry. If
the navigation was initiated with <span>replacement
enabled</span>, then the traversal must itself be initiated
with <span>replacement enabled</span>.</p>
</li>
</ol>
</dd>
</dl>
</li>
<li><p>The <span title="navigate">navigation algorithm</span> has
now <dfn title="concept-navigate-mature">matured</dfn>.</p></li>
<li><p><i>Fragment identifier loop</i>: Wait for a
user-agent-defined amount of time, as desired by the user agent
implementor. (This is intended to allow the user agent to optimize
the user experience in the face of performance concerns.)</p></li>
<li><p>If the <code>Document</code> object has no parser, or its
parser has <span title="stop parsing">stopped parsing</span>, or
the user agent has reason to believe the user is no longer
interested in scrolling to the fragment identifier, then abort
these steps.</p></li>
<li><p><span>Scroll to the fragment identifier</span> given in
<span>the document's current address</span>. If this fails to find
<span title="the indicated part of the document">an indicated part
of the document</span>, then return to the first step of these
substeps.</p></li>
</ol>
<p>The <span>task source</span> for this <span
title="concept-task">task</span> is the <span>networking task
source</span>.</p>
<h4 id="read-html"><dfn title="navigate-html">Page load processing model for HTML files</dfn></h4>
<p>When an HTML document is to be loaded in a <span>browsing
context</span>, the user agent must <span>create a
<code>Document</code> object</span>, mark it as being an <span
title="HTML documents">HTML document</span>, create an <span>HTML
parser</span>, associate it with the document, and begin to use the
bytes provided for the document as the <span>input stream</span> for
that parser.</p>
<p class="note">The <span>input stream</span> converts bytes into
characters for use in the <span
title="tokenization">tokenizer</span>. This process relies, in part,
on character encoding information found in the real <span
title="Content-Type">Content-Type metadata</span> of the resource;
the "sniffed type" is not used for this purpose.</p>
<!-- next two paragraphs are nearly identical to the navigate-text
section, keep them in sync -->
<p>When no more bytes are available, an EOF character is implied,
which eventually causes a <code title="event-load">load</code> event
to be fired.</p>
<p>After creating the <code>Document</code> object, but before any
script execution, certainly before the parser <span title="stop
parsing">stops</span>, the user agent must <span>update the session
history with the new page</span>.</p>
<p class="note"><span title="concept-appcache-init">Application
cache selection</span> happens <a href="#parser-appcache">in the
HTML parser</a>.</p>
<h4 id="read-xml"><dfn title="navigate-xml">Page load processing model for XML files</dfn></h4>
<p>When faced with displaying an XML file inline, user agents must
first <span>create a <code>Document</code> object</span>, following
the requirements of the XML and Namespaces in XML recommendations,
RFC 3023, DOM3 Core, and other relevant specifications. <a
href="#refsXML">[XML]</a> <a href="#refsXMLNS">[XMLNS]</a> <a
href="#refsRFC3023">[RFC3023]</a> <a
href="#refsDOMCORE">[DOMCORE]</a></p>
<p>The actual HTTP headers and other metadata, not the headers as
mutated or implied by the algorithms given in this specification,
are the ones that must be used when determining the character
encoding according to the rules given in the above
specifications. Once the character encoding is established, the
<span>document's character encoding</span> must be set to that
character encoding.</p>
<p>If the root element, as parsed according to the XML
specifications cited above, is found to be an <code>html</code>
element with an attribute <code
title="attr-html-manifest">manifest</code>, then, as soon as the
element is <span title="insert an element into a document">inserted
into the document</span>, the user agent must <span title="resolve a
url">resolve</span> the value of that attribute relative to that
element, and if that is successful, must run the <span
title="concept-appcache-init">application cache selection
algorithm</span> with the resulting <span>absolute URL</span> with
any <span title="url-fragment"><fragment></span> component
removed as the manifest URL, and passing in the newly-created
<code>Document</code>. Otherwise, if the attribute is absent or
resolving it fails, then as soon as the root element is <span
title="insert an element into a document">inserted into the
document</span>, the user agent must run the <span
title="concept-appcache-init">application cache selection
algorithm</span> with no manifest, and passing in the
<code>Document</code>.</p>
<p class="note">Because the processing of the <code
title="attr-html-manifest">manifest</code> attribute happens
only once the root element is parsed, any URLs referenced by
processing instructions before the root element (such as <code
title=""><?xml-stylesheet?></code> and <code
title=""><?xbl?></code> PIs) will be fetched from the network and
cannot be cached.</p><!-- v2: fix this somehow -->
<p>User agents may examine the namespace of the root
<code>Element</code> node of this <code>Document</code> object to
perform namespace-based dispatch to alternative processing tools,
e.g. determining that the content is actually a syndication feed and
passing it to a feed handler. If such processing is to take place,
abort the steps in this section, and jump to <a
href="#navigate-non-Document">the next step</a> (labeled
"non-document content") in the <span>navigate</span> steps
above.</p>
<p>Otherwise, then, with the newly created <code>Document</code>,
the user agents must <span>update the session history with the new
page</span>. User agents may do this before the complete document
has been parsed (thus achieving <i>incremental rendering</i>), and
must do this before any scripts are to be executed.</p>
<p>Error messages from the parse process (e.g. XML namespace
well-formedness errors) may be reported inline by mutating the
<code>Document</code>.</p>
<h4 id="read-text"><dfn title="navigate-text">Page load processing model for text files</dfn></h4>
<p>When a plain text document is to be loaded in a <span>browsing
context</span>, the user agent should <span>create a
<code>Document</code> object</span>, mark it as being an <span
title="HTML documents">HTML document</span>, create an <span>HTML
parser</span>, associate it with the document, act as if the
tokenizer had emitted a start tag token with the tag name "pre",
switch the <span>HTML parser</span>'s tokenizer to the
<span>PLAINTEXT state</span>, and begin to pass the stream of
characters in the plain text document to that tokenizer.</p>
<p>The rules for how to convert the bytes of the plain text document
into actual characters are defined in RFC 2046, RFC 2646, and
subsequent versions thereof. <a href="#refsRFC2046">[RFC2046]</a> <a
href="#refsRFC2646">[RFC2646]</a></p>
<p>The <span>document's character encoding</span> must be set to the
character encoding used to decode the document.</p>
<p>Upon creation of the <code>Document</code> object, the user agent
must run the <span title="concept-appcache-init">application cache
selection algorithm</span> with no manifest, and passing in the
newly-created <code>Document</code>.</p>
<!-- next two paragraphs are nearly identical to the navigate-html
section and similar to the "navigate-ua-inline" section, and the
next three are similar to the navigate-image and navigate-plugin
sections; keep them all in sync -->
<p>When no more characters are available, an EOF character is
implied, which eventually causes a <code
title="event-load">load</code> event to be fired.</p>
<p>After creating the <code>Document</code> object, but potentially
before the page has finished parsing, the user agent must
<span>update the session history with the new page</span>.</p>
<p>User agents may add content to the <code>head</code> element of
the <code>Document</code>, e.g. linking to a style sheet or an XBL
binding, providing script, giving the document a <code>title</code>,
etc.</p>
<h4 id="read-image"><dfn title="navigate-image">Page load processing model for images</dfn></h4>
<p>When an image resource is to be loaded in a <span>browsing
context</span>, the user agent should <span>create a
<code>Document</code> object</span>, mark it as being an <span
title="HTML documents">HTML document</span>, append an
<code>html</code> element to the <code>Document</code>, append a
<code>head</code> element and a <code>body</code> element to the
<code>html</code> element, append an <code>img</code> to the
<code>body</code> element, and set the <code
title="attr-img-src">src</code> attribute of the <code>img</code>
element to the address of the image.</p>
<!-- next three paragraphs are similar to the navigate-text section,
keep them in sync -->
<p>Then, the user agent must act as if it had <span title="stop
parsing">stopped parsing</span>.</p>
<p>Upon creation of the <code>Document</code> object, the user agent
must run the <span title="concept-appcache-init">application cache
selection algorithm</span> with no manifest, and passing in the
newly-created <code>Document</code>.</p>
<p>After creating the <code>Document</code> object, but potentially
before the page has finished fully loading, the user agent must
<span>update the session history with the new page</span>.</p>
<p>User agents may add content to the <code>head</code> element of
the <code>Document</code>, or attributes to the <code>img</code>
element, e.g. to link to a style sheet or an XBL binding, to provide
a script, to give the document a <code>title</code>, etc.</p>
<h4 id="read-plugin"><dfn title="navigate-plugin">Page load processing model for content that uses plugins</dfn></h4>
<p>When a resource that requires an external resource to be rendered
is to be loaded in a <span>browsing context</span>, the user agent
should <span>create a <code>Document</code> object</span>, mark it
as being an <span title="HTML documents">HTML document</span>,
append an <code>html</code> element to the <code>Document</code>,
append a <code>head</code> element and a <code>body</code> element
to the <code>html</code> element, append an <code>embed</code> to
the <code>body</code> element, and set the <code
title="attr-embed-src">src</code> attribute of the
<code>embed</code> element to the address of the resource.</p>
<!-- next three paragraphs are similar to the navigate-text section,
keep them in sync -->
<p>Then, the user agent must act as if it had <span title="stop
parsing">stopped parsing</span>.</p>
<p>Upon creation of the <code>Document</code> object, the user agent
must run the <span title="concept-appcache-init">application cache
selection algorithm</span> with no manifest, and passing in the
newly-created <code>Document</code>.</p>
<p>After creating the <code>Document</code> object, but potentially
before the page has finished fully loading, the user agent must
<span>update the session history with the new page</span>.</p>
<p>User agents may add content to the <code>head</code> element of
the <code>Document</code>, or attributes to the <code>embed</code>
element, e.g. to link to a style sheet or an XBL binding, or to give
the document a <code>title</code>.</p>
<p class="note" id="sandboxPluginNavigate">If the <span>sandboxed
plugins browsing context flag</span> is set on the <span>browsing
context</span>, the synthesized <code>embed</code> element will <a
href="#sandboxPluginEmbed">fail to render the content</a>.</p>
<h4 id="read-ua-inline"><dfn title="navigate-ua-inline">Page load processing model for inline content that doesn't have a DOM</dfn></h4>
<p>When the user agent is to display a user agent page inline in a
<span>browsing context</span>, the user agent should <span>create a
<code>Document</code> object</span>, mark it as being an <span
title="HTML documents">HTML document</span>, and then either
associate that <code>Document</code> with a custom rendering that is
not rendered using the normal <code>Document</code> rendering rules,
or mutate that <code>Document</code> until it represents the content
the user agent wants to render.</p>
<!-- next two paragraphs are similar to the navigate-text section,
keep them in sync -->
<p>Once the page has been set up, the user agent must act as if it
had <span title="stop parsing">stopped parsing</span>.</p>
<p>Upon creation of the <code>Document</code> object, the user agent
must run the <span title="concept-appcache-init">application cache
selection algorithm</span> with no manifest, passing in the
newly-created <code>Document</code>.</p>
<p>After creating the <code>Document</code> object, but potentially
before the page has been completely set up, the user agent must
<span>update the session history with the new page</span>.</p>
<h4 id="scroll-to-fragid"><dfn title="navigate-fragid">Navigating to a fragment identifier</dfn></h4>
<p>When a user agent is supposed to navigate to a fragment
identifier, then the user agent must <span>queue a task</span> to
run the following steps:</p>
<ol>
<li><p>Remove all the entries after the <span>current entry</span>
in the <span>browsing context</span>'s <code>Document</code>
object's <code>History</code> object.</p> <p class="note">This <a
href="#history-notes">doesn't necessarily have to affect</a> the
user agent's user interface.</p> </li>
<li><p>Append a new entry at the end of the <code>History</code>
object representing the new resource and its <code>Document</code>
object and related state, and set its URL to the address to which
the user agent was <span title="navigate">navigating</span>. (This
will be the same as <span>the document's address</span>, but with a
new fragment identifier.)</p></li>
<li><p><span>Traverse the history</span> to the new entry. This
will <span>scroll to the fragment identifier</span> given in
<span>the document's current address</span>.</p></li>
</ol>
<p class="note">If the scrolling fails because the relevant ID has
not yet been parsed, then the original <span
title="navigate">navigation</span> algorithm will take care of the
scrolling instead, as the last few steps of its <span>update the
session history with the new page</span> algorithm.</p>
<hr>
<p>When the user agent is required to <dfn>scroll to the fragment
identifier</dfn>, it must change the scrolling position of the
document, or perform some other action, such that <span>the
indicated part of the document</span> is brought to the user's
attention. If there is no indicated part, then the user agent must
not scroll anywhere.</p>
<p><dfn>The indicated part of the document</dfn> is the one that the
fragment identifier, if any, identifies. The semantics of the
fragment identifier in terms of mapping it to a specific DOM Node is
defined by the specification that defines the <span>MIME type</span>
used by the <code>Document</code> (for example, the processing of
fragment identifiers for <span title="XML MIME type">XML MIME
types</span> is the responsibility of RFC3023).</p>
<p>For HTML documents (and the <code>text/html</code> <span>MIME type</span>),
the following processing model must be followed to determine what
<span>the indicated part of the document</span> is.</p>
<ol>
<li><p><span title="parse a url">Parse</span> the <span>URL</span>,
and let <var title="">fragid</var> be the <span
title="url-fragment"><fragment></span> component of the
URL.</p></li><!-- parsing can't fail, since we checked earlier on
when navigating -->
<li><p>If <var title="">fragid</var> is the empty string, then the
indicated part of the document is the top of the document.</p></li>
<li><p>Let <var title="">decoded fragid</var> be the result of
expanding any sequences of percent-encoded octets in <var
title="">fragid</var> that are valid UTF-8 sequences into Unicode
characters as defined by UTF-8. If any percent-encoded octets in
that string are not valid UTF-8 sequences, then skip this step and
the next one.</p>
<li><p>If this step was not skipped and there is an element in the
DOM that has an ID exactly equal to <var title="">decoded
fragid</var>, then the first such element in tree order is
<span>the indicated part of the document</span>; stop the algorithm
here.</p></li>
<li><p>If there is an <code>a</code> element in the DOM that has a
<code title="attr-a-name">name</code> attribute whose value is
exactly equal to <var title="">fragid</var> (<em>not</em> <var
title="">decoded fragid</var>), then the first such element in tree
order is <span>the indicated part of the document</span>; stop the
algorithm here.</p></li>
<li><p>Otherwise, there is no indicated part of the
document.</p></li>
</ol>
<p>For the purposes of the interaction of HTML with Selectors' <code
title="selector-target">:target</code> pseudo-class, the
<dfn><i>target element</i></dfn> is <span>the indicated part of the
document</span>, if that is an element; otherwise there is no
<i>target element</i>. <a href="#refsSELECTORS">[SELECTORS]</a></p>
<h4>History traversal</h4>
<p>When a user agent is required to <dfn>traverse the history</dfn>
to a <i>specified entry</i>, optionally with <span>replacement
enabled</span>, the user agent must act as follows:</p>
<ol>
<li><p>If there is no longer a <code>Document</code> object for the
entry in question, the user agent must <span>navigate</span> the
browsing context to the location for that entry to perform an
<span>entry update</span> of that entry, and abort these steps. The
"<span>navigate</span>" algorithm reinvokes this "traverse"
algorithm to complete the traversal, at which point there
<em>is</em> a <code>Document</code> object and so this step gets
skipped. The navigation must be done using the same <span>source
browsing context</span> as was used the first time this entry was
created. (This can never happen with <span>replacement
enabled</span>.)</p></li>
<li><p>Release the <span>storage mutex</span>.</p></li>
<li>
<p>If appropriate, update the <span>current entry</span> in the
<span>browsing context</span>'s <code>Document</code> object's
<code>History</code> object to reflect any state that the user
agent wishes to persist. The entry is then said to be <dfn>an
entry with persisted user state</dfn>.</p>
<p class="example">For example, some user agents might want to
persist the scroll position, or the values of form controls.</p>
</li>
<li><p>If the <i>specified entry</i> has a different
<code>Document</code> object than the <span>current entry</span>
then the user agent must run the following substeps:</p>
<ol>
<li>If the browsing context is a <span>top-level browsing
context</span> (and not an <span>auxiliary browsing
context</span>), and the <span>origin</span> of the
<code>Document</code> of the <i>specified entry</i> is not the
<span title="same origin">same</span> as the <span>origin</span>
of the <code>Document</code> of the <span>current entry</span>,
then the following sub-sub-steps must be run:
<ol>
<li>The current <span>browsing context name</span> must be
stored with all the entries in the history that are associated
with <code>Document</code> objects with the <span>same
origin</span> as the <span>active document</span> <em>and</em>
that are contiguous with the <span>current entry</span>.</li>
<li id="resetBCName">The browsing context's <span>browsing
context name</span> must be unset.</li>
</ol>
</li>
<li id="appcache-history-2">The user agent must make the
<i>specified entry</i>'s <code>Document</code> object the
<span>active document</span> of the <span>browsing
context</span>.</li>
<li>If the <i>specified entry</i> has a <span>browsing
context name</span> stored with it, then the following
sub-sub-steps must be run:
<ol>
<li>The browsing context's <span>browsing context name</span>
must be set to the name stored with the specified entry.</li>
<li>Any <span>browsing context name</span> stored with the
entries in the history that are associated with
<code>Document</code> objects with the <span>same origin</span>
as the new <span>active document</span>, and that are
contiguous with the specified entry, must be cleared.</li>
</ol>
</li>
<li id="history-autocomplete"><p>If the <i>specified entry</i>'s
<code>Document</code> has any <code>input</code> elements whose
<span>resulting autocompletion state</span> is <i
title="">off</i>, invoke the <span
title="concept-form-reset-control">reset algorithm</span> of each
of those elements.</p></li>
<li><p>If the <span>current document readiness</span> of the
<i>specified entry</i>'s <code>Document</code> is "complete",
<span>queue a task</span> to <span>fire a simple event</span>
named <code title="event-pageshow">pageshow</code> at that
<code>Document</code>'s <code>Window</code> object.</p></li>
</ol>
</li>
<li><p>Set <span>the document's current address</span> to the URL
of the <i>specified entry</i>.</p></li>
<li><p>If the <i>specified entry</i> has a URL that differs from
the <span>current entry</span>'s only by its fragment identifier,
and the two share the same <code>Document</code> object, then let
<var title="">hash changed</var> be true. Otherwise, let <var
title="">hash changed</var> be false.</p></li>
<li><p>If the traversal was initiated with <dfn>replacement
enabled</dfn>, remove the entry immediately before the
<var title="">specified entry</var> in the session history.</p>
<li><p>If <var title="">hash changed</var> is true, then, if the
new URL has a fragment identifier, <span>scroll to the fragment
identifier</span>.</p></li>
<li><p>If the entry is <span>an entry with persisted user
state</span>, the user agent may update aspects of the document
view, for instance the scroll position or values of form fields,
that it had previously recorded.</p></li>
<li><p>If the <i>specified entry</i> is a state object or the
first entry for a <code>Document</code>, the user agent must <span
title="activate the state object">activate that
entry</span>.</p></li>
<li><p>If <var title="">hash changed</var> is true, then
synchronously <span>fire a simple event</span> with the name <code
title="event-hashchange">hashchange</code> at the <span>browsing
context</span>'s <code>Window</code> object.</p></li>
<li><p>Release the <span>storage mutex</span> again.</p></li>
<li><p>The <span>current entry</span> is now the <i>specified
entry</i>.</p></li>
</ol>
</div>
<h4>Unloading documents</h4>
<div class="impl">
<p>A <code>Document</code> has a <var title="">salvageable</var>
state, which is initially true.</p>
<hr>
<p>When a user agent is to <dfn>prompt to unload a document</dfn>,
it must run the following steps.</p>
<ol>
<li><p>Let <var title="">event</var> be a new
<code>BeforeUnloadEvent</code> event object with the name <code
title="event-beforeunload">beforeunload</code>, which does not
bubble but is cancelable.</p></li>
<li><p>Dispatch <var title="">event</var> at the
<code>Document</code>'s <code>Window</code> object.</p></li>
<li><p>Release the <span>storage mutex</span>.</p></li>
<li><p>If any event listeners were triggered by the previous step,
then set the <code>Document</code>'s <var
title="">salvageable</var> state to false.</p></li>
<li>
<p>If the <code
title="dom-BeforeUnloadEvent-returnValue">returnValue</code>
attribute of the <var title="">event</var> object is not the empty
string, or if the event was canceled, then the user agent should
ask the user to confirm that they wish to unload the document.</p>
<p>The prompt shown by the user agent may include the string of
the <code
title="dom-BeforeUnloadEvent-returnValue">returnValue</code>
attribute, or some leading subset thereof. (A user agent may want
to truncate the string to 1024 characters for display, for
instance.)</p>
<p>The user agent must <span>pause</span> while waiting for the
user's response.</p>
<p>If the user did not confirm the page navigation, then the user
agent <dfn>refused to allow the document to be unloaded</dfn>.</p>
</li>
</ol>
<hr>
<p>When a user agent is to <dfn>unload a document</dfn>, it must run
the following steps. These steps are passed an argument, <var
title="">recycle</var>, which is either true or false, indicating
whether the <code>Document</code> object is going to be
re-used. (This is set by the <code
title="dom-document-open">document.open()</code> method.)</p>
<ol>
<li><p><span>Fire a simple event</span> named <code
title="event-pagehide">pagehide</code> at the
<code>Document</code>'s <code>Window</code> object.</p></li>
<li><p><span>Fire a simple event</span> named <code
title="event-unload">unload</code> at the <code>Document</code>'s
<code>Window</code> object.</p></li>
<li><p>Release the <span>storage mutex</span>.</p></li>
<li><p>If any event listeners were triggered by the previous step,
then set the <code>Document</code> object's <var
title="">salvageable</var> state to false.</p></li>
<li><p>If there are any outstanding transactions that have
callbacks that involve <span title="concept-script">scripts</span>
whose <span title="script's global object">global object</span> is
the <code>Document</code>'s <code>Window</code> object, roll them
back (without invoking any of the callbacks) and set <var
title="">salvageable</var> to false.</p>
<li><p>Empty the <code>Document</code>'s <code>Window</code>'s
<span>list of active timeouts</span> and its <span>list of active
intervals</span>.</p></li>
<li><p>If <var title="">salvageable</var> and <var
title="">recycle</var> are both false, <span title="discard a
document">discard the <code>Document</code></span>.</p></li>
</ol>
<h5>Event definition</h5>
</div>
<pre class="idl">interface <dfn>BeforeUnloadEvent</dfn> : Event {
attribute DOMString <span title="dom-BeforeUnloadEvent-returnValue">returnValue</span>;
};</pre>
<dl class="domintro">
<dt><var title="">event</var> . <code title="dom-BeforeUnloadEvent-returnValue">returnValue</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the current return value of the event (the message to show the user).</p>
<p>Can be set, to update the message.</p>
</dd>
</dl>
<p class="note">There are no <code>BeforeUnloadEvent</code>-specific
initialization methods.</p>
<div class="impl">
<p>The <dfn
title="dom-BeforeUnloadEvent-returnValue"><code>returnValue</code></dfn>
attribute represents the message to show the user. When the event is
created, the attribute must be set to the empty string. On getting,
it must return the last value it was set to. On setting, the
attribute must be set to the new value.</p>
</div>
<h4>Aborting a document load</h4>
<p>If the user cancels any instance of the <span
title="fetch">fetching algorithm</span> in the context of a
<code>Document</code> in a <span>browsing context</span>, then, if
that <code>Document</code> is an <span>active document</span>, the
user agent must <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-abort">abort</code> at that
<code>Document</code>'s <code>Window</code> object.</p>
<!-- I'd love to make this more precise, anyone have any suggestions
on what it should say? -->
<h3 id="links">Links</h3>
<h4>Hyperlink elements</h4>
<p>The <code>a</code>, <code>area</code>, and <code>link</code>
elements can, in certain situations described in the definitions of
those elements, represent <dfn
title="hyperlink">hyperlinks</dfn>.</p>
<p>The <dfn title="attr-hyperlink-href"><code>href</code></dfn>
attribute on a hyperlink element must have a value that is a
<span>valid URL</span>. This URL is the <em>destination
resource</em> of the hyperlink.</p>
<div class="note">
<p>The <code title="attr-hyperlink-href">href</code> attribute on
<code>a</code> and <code>area</code> elements is not required; when
those elements do not have <code
title="attr-hyperlink-href">href</code> attributes they do not
represent hyperlinks.</p>
<p>The <code title="attr-link-href">href</code> attribute on the
<code>link</code> element <em>is</em> required, but whether a
<code>link</code> element represents a hyperlink or not depends on
the value of the <code title="attr-link-rel">rel</code> attribute
of that element.</p>
</div>
<p>The <dfn title="attr-hyperlink-target"><code>target</code></dfn>
attribute, if present, must be a <span>valid browsing context name
or keyword</span>. It gives the name of the <span>browsing
context</span> that will be used. <span class="impl">User agents use
this name when <span>following hyperlinks</span>.</span></p>
<p>The <dfn id="ping"
title="attr-hyperlink-ping"><code>ping</code></dfn> attribute, if
present, gives the URLs of the resources that are interested in
being notified if the user follows the hyperlink. The value must be
a <span>set of space-separated tokens</span>, each of which must be a
<span title="valid URL">valid URL</span>. <span class="impl">The
value is used by the user agent for <span>hyperlink
auditing</span>.</span></p>
<p>For <code>a</code> and <code>area</code> elements that represent
hyperlinks, the relationship between the document containing the
hyperlink and the destination resource indicated by the hyperlink is
given by the value of the element's <dfn
title="attr-hyperlink-rel"><code>rel</code></dfn> attribute, which
must be a <span>set of space-separated tokens</span>. The <a
href="#linkTypes">allowed values and their meanings</a> are defined
below. The <code title="attr-hyperlink-rel">rel</code> attribute has
no default value. If the attribute is omitted or if none of the
values in the attribute are recognized by the user agent, then the
document has no particular relationship with the destination
resource other than there being a hyperlink between the two.</p>
<p>The <dfn title="attr-hyperlink-media"><code>media</code></dfn>
attribute describes for which media the target document was
designed. It is purely advisory. The value must be a <span>valid
media query</span>. The default, if the <code
title="attr-hyperlink-media">media</code> attribute is omitted, is
"<code title="">all</code>".</p>
<p>The <dfn
title="attr-hyperlink-hreflang"><code>hreflang</code></dfn>
attribute on hyperlink elements, if present, gives the language of
the linked resource. It is purely advisory. The value must be a
valid BCP 47 language code. <a href="#refsBCP47">[BCP47]</a>
<span class="impl">User agents must not consider this attribute
authoritative — upon fetching the resource, user agents must
use only language information associated with the resource to
determine its language, not metadata included in the link to the
resource.</span></p>
<p>The <dfn title="attr-hyperlink-type"><code>type</code></dfn>
attribute, if present, gives the <span>MIME type</span> of the linked
resource. It is purely advisory. The value must be a <span>valid
MIME type</span>, optionally with parameters. <span
class="impl">User agents must not consider the <code
title="attr-hyperlink-type">type</code> attribute authoritative
— upon fetching the resource, user agents must not use
metadata included in the link to the resource to determine its
type.</span></p>
<div class="impl">
<h4><dfn>Following hyperlinks</dfn></h4>
<p>When a user <em>follows a hyperlink</em>, the user agent must
<span title="resolve a url">resolve</span> the <span>URL</span>
given by the <code title="attr-hyperlink-href">href</code> attribute
of that hyperlink, relative to the hyperlink element, and if that is
successful, must <span>navigate</span> a <span>browsing
context</span> to the resulting <span>absolute URL</span>. In the
case of server-side image maps, the URL of the hyperlink must
further have its <var>hyperlink suffix</var> appended to it.</p>
<p>If <span title="resolve a url">resolving</span> the
<span>URL</span> fails, the user agent may report the error to the
user in a user-agent-specific manner, may navigate to an error page
to report the error, or may ignore the error and do nothing.</p>
<p>If the user indicated a specific <span>browsing context</span>
when following the hyperlink, or if the user agent is configured to
follow hyperlinks by navigating a particular browsing context, then
that must be the <span>browsing context</span> that is
navigated.</p>
<p>Otherwise, if the hyperlink element is an <code>a</code> or
<code>area</code> element that has a <code
title="attr-hyperlink-target">target</code> attribute, then the
<span>browsing context</span> that is navigated must be chosen by
applying <span>the rules for choosing a browsing context given a
browsing context name</span>, using the value of the <code
title="attr-hyperlink-target">target</code> attribute as the
browsing context name. If these rules result in the creation of a
new <span>browsing context</span>, it must be navigated with
<span>replacement enabled</span>.</p>
<p>Otherwise, if the hyperlink element is a <span
title="rel-sidebar-hyperlink">sidebar hyperlink</span> and the user
agent implements a feature that can be considered a secondary
browsing context, such a secondary browsing context may be selected
as the browsing context to be navigated.</p>
<p>Otherwise, if the hyperlink element is an <code>a</code> or
<code>area</code> element with no <code
title="attr-hyperlink-target">target</code> attribute, but one of
the child nodes of <span>the <code>head</code> element</span> is a
<code>base</code> element with a <code
title="attr-base-target">target</code> attribute, then the browsing
context that is navigated must be chosen by applying <span>the rules
for choosing a browsing context given a browsing context name</span>,
using the value of the <code title="attr-base-target">target</code>
attribute of the first such <code>base</code> element as the
browsing context name. If these rules result in the creation of a
new <span>browsing context</span>, it must be navigated with
<span>replacement enabled</span>.</p>
<p>Otherwise, the browsing context that must be navigated is the
same browsing context as the one which the hyperlink element itself
is in.</p>
<p>The navigation must be done with the <span>browsing
context</span> that contains the <code>Document</code> object with
which the hyperlink's element in question is associated as the
<span>source browsing context</span>.</p>
<h5><dfn>Hyperlink auditing</dfn></h5>
<p>If an <code>a</code> or <code>area</code> hyperlink element has a
<code title="attr-hyperlink-ping">ping</code> attribute, and the
user follows the hyperlink, and the hyperlink's <span>URL</span> can
be <span title="resolve a url">resolved</span>, relative to the
hyperlink element, without failure, then the user agent must take
the <code title="attr-hyperlink-ping">ping</code> attribute's value,
<span title="split a string on spaces">split that string on
spaces</span>, <span title="resolve a url">resolve</span> each
resulting token relative to the hyperlink element, and then should
send a request (as described below) to each of the resulting <span
title="absolute URL">absolute URLs</span>. (Tokens that fail to
resolve are ignored.) This may be done in parallel with the primary
request, and is independent of the result of that request.</p>
<p>User agents should allow the user to adjust this behavior, for
example in conjunction with a setting that disables the sending of
HTTP <code title="http-referer">Referer</code> (sic) headers. Based
on the user's preferences, UAs may either <span>ignore</span> the
<code title="attr-hyperlink-ping">ping</code> attribute altogether,
or selectively ignore URLs in the list (e.g. ignoring any
third-party URLs).</p>
<p>For URLs that are HTTP URLs, the requests must be performed by
<span title="fetch">fetching</span> the specified URLs using the
POST method, with an entity body with the <span>MIME type</span>
<code>text/ping</code> consisting of the four-character string
"<code title="">PING</code>", from the <span>origin</span> of the
<code>Document</code> containing the <span>hyperlink</span>. <!--
not http-origin privacy sensitive --> All relevant cookie and HTTP
authentication headers must be included in the request. Which other
headers are required depends on the URLs involved.</p>
<dl class="switch">
<dt>If both the <span title="the document's address">address</span>
of the <code>Document</code> object containing the hyperlink being
audited and the ping URL have the <span>same origin</span></dt>
<dd>The request must include a <code
title="http-ping-from">Ping-From</code> HTTP header with, as its
value, the <span title="the document's address">address</span> of
the document containing the hyperlink, and a <code
title="http-ping-to">Ping-To</code> HTTP header with, as its value,
the address of the <span>absolute URL</span> of the target of the
hyperlink. The request must not include a <code
title="http-referer">Referer</code> (sic) HTTP header. <!-- because
otherwise it would look like a trustable same-origin POST --></dd>
<dt>Otherwise, if the origins are different, but the document
containing the hyperlink being audited was not retrieved over an
encrypted connection</dt>
<dd>The request must include a <code title="">Referer</code> (sic)
HTTP header [sic] with, as its value, the <span title="the
document's current address">current address</span> of the document
containing the hyperlink, a <code
title="http-ping-from">Ping-From</code> HTTP header with the same
value, and a <code title="http-ping-to">Ping-To</code> HTTP header
with, as its value, the address of the target of the
hyperlink.</dd>
<dt>Otherwise, the origins are different and the document
containing the hyperlink being audited was retrieved over an
encrypted connection</dt>
<dd>The request must include a <code
title="http-ping-to">Ping-To</code> HTTP header with, as its value,
the address of the target of the hyperlink. The request must
neither include a <code title="">Referer</code> (sic) HTTP header
nor include a <code title="http-ping-from">Ping-From</code> HTTP
header.</dd>
</dl>
<p class="note">To save bandwidth, implementors might also wish to
consider omitting optional headers such as <code>Accept</code> from
these requests.</p>
<p>User agents must, unless otherwise specified by the user, honor
the HTTP headers (including, in particular, redirects and HTTP
cookie headers), but must ignore any entity bodies returned in the
responses. User agents may close the connection prematurely once
they start receiving an entity body. <a
href="#refsCOOKIES">[COOKIES]</a></p>
<p>For URLs that are not HTTP URLs, the requests must be performed
by <span title="fetch">fetching</span> the specified URL normally,
and discarding the results.</p>
<p>When the <code title="attr-hyperlink-ping">ping</code> attribute is
present, user agents should clearly indicate to the user that
following the hyperlink will also cause secondary requests to be
sent in the background, possibly including listing the actual target
URLs.</p>
<p class="example">For example, a visual user agent could include
the hostnames of the target ping URLs along with the hyperlink's
actual URL in a status bar or tooltip.</p>
</div>
<div class="note">
<p>The <code title="attr-hyperlink-ping">ping</code> attribute is redundant
with pre-existing technologies like HTTP redirects and JavaScript
in allowing Web pages to track which off-site links are most
popular or allowing advertisers to track click-through rates.</p>
<p>However, the <code title="attr-hyperlink-ping">ping</code> attribute
provides these advantages to the user over those alternatives:</p>
<ul>
<li>It allows the user to see the final target URL
unobscured.</li>
<li>It allows the UA to inform the user about the out-of-band
notifications.</li>
<li>It allows the user to disable the notifications without losing
the underlying link functionality.</li>
<li>It allows the UA to optimize the use of available network
bandwidth so that the target page loads faster.</li>
</ul>
<p>Thus, while it is possible to track users without this feature,
authors are encouraged to use the <code
title="attr-hyperlink-ping">ping</code> attribute so that the user
agent can make the user experience more transparent.</p>
</div>
<!-- resolving ping urls happens at audit time, so base URL changes
affect the values of ping attributes -->
<h4 id="linkTypes">Link types</h4>
<p>The following table summarizes the link types that are defined by
this specification. This table is non-normative; the actual
definitions for the link types are given in the next few
sections.</p>
<p>In this section, the term <i>referenced document</i> refers to
the resource identified by the element representing the link, and
the term <i>current document</i> refers to the resource within
which the element representing the link finds itself.</p>
<div class="impl">
<p>To determine which link types apply to a <code>link</code>,
<code>a</code>, or <code>area</code> element, the element's <code
title="">rel</code> attribute must be <span title="split a string on
spaces">split on spaces</span>. The resulting tokens are the link
types that apply to that element.</p>
</div>
<p>Except where otherwise specified, a keyword must not be specified
more than once per <code title="attr-rel-hyperlink">rel</code>
attribute.</p>
<p>The link types are <span>ASCII case-insensitive</span>
values<span class="impl">, and must be compared as such</span>.</p>
<p class="example">Thus, <code title="">rel="next"</code> is the
same as <code title="">rel="NEXT"</code>.</p>
<table>
<thead>
<tr>
<th rowspan="2">Link type</th>
<th colspan="2">Effect on...</th>
<th rowspan="2">Brief description</th>
</tr>
<tr>
<th><code>link</code></th>
<th><code>a</code> and <code>area</code></th>
</tr>
</thead>
<tbody>
<tr>
<td><code title="rel-alternate">alternate</code></td> <!-- second most used <link rel> value -->
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Gives alternate representations of the current document.</td>
</tr>
<tr>
<td><code title="rel-archives">archives</code></td>
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Provides a link to a collection of records, documents, or other materials of historical interest.</td>
</tr>
<tr>
<td><code title="rel-author">author</code></td>
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Gives a link to the current document's author.</td>
</tr>
<tr>
<td><code title="rel-bookmark">bookmark</code></td> <!-- fourth most used <a rel> value -->
<td><em>not allowed</em></td>
<td><span>Hyperlink</span></td>
<td>Gives the permalink for the nearest ancestor section.</td>
</tr>
<!-- (commented out on the assumption that rel=contact is really XFN)
<tr>
<td><code title="rel-contact">contact</code></td> <!- 8th most used <a rel> value ->
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Gives a link to contact information for the current document.</td>
</tr>
-->
<tr>
<td><code title="rel-external">external</code></td> <!-- fifth and sixth most used <a rel> value (sixth is "external nofollow") -->
<td><em>not allowed</em></td>
<td><span>Hyperlink</span></td>
<td>Indicates that the referenced document is not part of the same site as the current document.</td>
</tr>
<tr>
<td><code title="rel-first">first</code></td>
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Indicates that the current document is a part of a series, and that the first document in the series is the referenced document.</td>
</tr>
<tr>
<td><code title="rel-help">help</code></td>
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Provides a link to context-sensitive help.</td>
</tr>
<tr>
<td><code title="rel-icon">icon</code></td> <!-- link rel="shortcut icon" and its ilk are the fourth, sixth, and ninth most used values -->
<td><span title="external resource link">External Resource</span></td>
<td><em>not allowed</em></td>
<td>Imports an icon to represent the current document.</td>
</tr>
<tr>
<td><code title="rel-index">index</code></td> <!-- used more than "top" and "contents" on <link> (though on <a>, "contents" wins) -->
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Gives a link to the document that provides a table of contents or index listing the current document.</td>
</tr>
<tr>
<td><code title="rel-last">last</code></td>
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Indicates that the current document is a part of a series, and that the last document in the series is the referenced document.</td>
</tr>
<tr>
<td><code title="rel-license">license</code></td> <!-- seventh most used <a rel> value -->
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Indicates that the main content of the current document is covered by the copyright license described by the referenced document.</td>
</tr>
<tr>
<td><code title="rel-next">next</code></td>
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Indicates that the current document is a part of a series, and that the next document in the series is the referenced document.</td>
</tr>
<tr>
<td><code title="rel-nofollow">nofollow</code></td> <!-- most used <a rel> value (and sixth most used is "external nofollow") -->
<td><em>not allowed</em></td>
<td><span>Hyperlink</span></td>
<td>Indicates that the current document's original author or publisher does not endorse the referenced document.</td>
</tr>
<tr>
<td><code title="rel-noreferrer">noreferrer</code></td>
<td><em>not allowed</em></td>
<td><span>Hyperlink</span></td>
<td>Requires that the user agent not send an HTTP <code title="">Referer</code> (sic) header if the user follows the hyperlink.</td>
</tr>
<tr>
<td><code title="rel-pingback">pingback</code></td>
<td><span title="external resource link">External Resource</span></td>
<td><em>not allowed</em></td>
<td>Gives the address of the pingback server that handles pingbacks to the current document.</td>
</tr>
<tr>
<td><code title="rel-prefetch">prefetch</code></td>
<td><span title="external resource link">External Resource</span></td>
<td><em>not allowed</em></td>
<td>Specifies that the target resource should be preemptively cached.</td>
</tr>
<tr>
<td><code title="rel-prev">prev</code></td> <!-- prev is used more than previous -->
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Indicates that the current document is a part of a series, and that the previous document in the series is the referenced document.</td>
</tr>
<tr>
<td><code title="rel-search">search</code></td> <!-- used quite a bit -->
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Gives a link to a resource that can be used to search through the current document and its related pages.</td>
</tr>
<tr>
<td><code title="rel-stylesheet">stylesheet</code></td> <!-- most commonly used <link rel> value, variants came in 7th, 8th, 12th, 17th... -->
<td><span title="external resource link">External Resource</span></td>
<td><em>not allowed</em></td>
<td>Imports a stylesheet.</td>
</tr>
<tr>
<td><code title="rel-sidebar">sidebar</code></td> <!-- used quite a bit -->
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Specifies that the referenced document, if retrieved, is intended to be shown in the browser's sidebar (if it has one).</td>
</tr>
<tr>
<td><code title="rel-tag">tag</code></td> <!-- second and third most used <a rel> value (third is technically "category tag"). -->
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Gives a tag (identified by the given address) that applies to the current document.</td>
</tr>
<tr>
<td><code title="rel-up">up</code></td>
<td><span title="hyperlink link">Hyperlink</span></td>
<td><span>Hyperlink</span></td>
<td>Provides a link to a document giving the context for the current document.</td>
</tr>
</tbody>
</table>
<div class="impl">
<p>Some of the types described below list synonyms for these
values. These <!--<span class="impl">-->are to be handled as
specified by user agents, but<!--</span>--> must not be used in
documents.</p>
</div>
<!-- v2 ideas:
* rel="script"
* rel="related" // see also
* http://microformats.org/wiki/rel-enclosure
-->
<h5>Link type "<dfn title="rel-alternate"><code>alternate</code></dfn>"</h5>
<p>The <code title="rel-alternate">alternate</code> keyword may be
used with <code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, if the <code
title="attr-link-rel">rel</code> attribute does not also contain the
keyword <code title="rel-stylesheet">stylesheet</code>, it creates a
<span title="hyperlink link">hyperlink</span>; but if it
<em>does</em> also contain the keyword <code
title="rel-stylesheet">stylesheet</code>, the <code
title="rel-alternate">alternate</code> keyword instead modifies the
meaning of the <code title="rel-stylesheet">stylesheet</code>
keyword in the way described for that keyword, and the rest of this
subsection doesn't apply.</p>
<p>The <code title="rel-alternate">alternate</code> keyword
indicates that the referenced document is an alternate
representation of the current document.</p>
<p>The nature of the referenced document is given by the <code
title="attr-hyperlink-media">media</code>, <code
title="attr-hyperlink-hreflang">hreflang</code>, and <code
title="attr-hyperlink-type">type</code> attributes.</p>
<p>If the <code title="rel-alternate">alternate</code> keyword is
used with the <code title="attr-hyperlink-media">media</code>
attribute, it indicates that the referenced document is intended for
use with the media specified.</p>
<p>If the <code title="rel-alternate">alternate</code> keyword is
used with the <code title="attr-hyperlink-hreflang">hreflang</code>
attribute, and that attribute's value differs from the <span>root
element</span>'s <span>language</span>, it indicates that the
referenced document is a translation.</p>
<p>If the <code title="rel-alternate">alternate</code> keyword is
used with the <code title="attr-hyperlink-type">type</code>
attribute, it indicates that the referenced document is a
reformulation of the current document in the specified format.</p>
<p>The <code title="attr-hyperlink-media">media</code>, <code
title="attr-hyperlink-hreflang">hreflang</code>, and <code
title="attr-hyperlink-type">type</code> attributes can be combined
when specified with the <code title="rel-alternate">alternate</code>
keyword.</p>
<div class="example">
<p>For example, the following link is a French translation that
uses the PDF format:</p>
<pre><link rel=alternate type=application/pdf hreflang=fr href=manual-fr></pre>
</div>
<div class="impl">
<p>If the <code title="rel-alternate">alternate</code> keyword is
used with the <code title="attr-hyperlink-type">type</code>
attribute set to the value <code title="">application/rss+xml</code>
or the value <code title="">application/atom+xml</code>, then it
indicates that the referenced document is a syndication feed (though
not necessarily syndicating exactly the same content as the current
page).</p>
<div class="impl">
<p>The first <code>link</code>, <code>a</code>, or <code>area</code>
element in the document (in tree order) with the <code
title="rel-alternate">alternate</code> keyword used with the <code
title="attr-hyperlink-type">type</code> attribute set to the value
<code title="">application/rss+xml</code> or the value <code
title="">application/atom+xml</code> must be treated as the default
syndication feed for the purposes of feed autodiscovery.</p>
<div class="example">
<p>The following <code>link</code> element gives the syndication
feed for the current page:</p>
<pre><link rel="alternate" type="application/atom+xml" href="data.xml"></pre>
<p>The following extract offers various different syndication
feeds:</p>
<pre><p>You can access the planets database using Atom feeds:</p>
<ul>
<li><a href="recently-visited-planets.xml" rel="alternate" type="application/atom+xml">Recently Visited Planets</a></li>
<li><a href="known-bad-planets.xml" rel="alternate" type="application/atom+xml">Known Bad Planets</a></li>
<li><a href="unexplored-planets.xml" rel="alternate" type="application/atom+xml">Unexplored Planets</a></li>
</ul></pre>
</div>
</div>
</div>
<p>The <code title="rel-alternate">alternate</code> link
relationship is transitive — that is, if a document links to
two other documents with the link type "<code
title="rel-alternate">alternate</code>", then, in addition to
implying that those documents are alternative representations of the
first document, it is also implying that those two documents are
alternative representations of each other.</p>
<h5>Link type "<dfn title="rel-archives"><code>archives</code></dfn>"</h5>
<p>The <code title="rel-archives">archives</code> keyword may be
used with <code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-archives">archives</code> keyword indicates
that the referenced document describes a collection of records,
documents, or other materials of historical interest.</p>
<p class="example">A blog's index page could link to an index of the
blog's past posts with <code title="">rel="archives"</code>.</p>
<div class="impl">
<p><strong>Synonyms</strong>: For historical reasons, user agents
must also treat the keyword "<code title="">archive</code>" like the
<code title="rel-archives">archives</code> keyword.</p>
</div>
<h5>Link type "<dfn title="rel-author"><code>author</code></dfn>"</h5>
<p>The <code title="rel-author">author</code> keyword may be
used with <code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>For <code>a</code> and <code>area</code> elements, the <code
title="rel-author">author</code> keyword indicates that the
referenced document provides further information about the author of
the nearest <code>article</code> element ancestor of the element
defining the hyperlink, if there is one, or of the page as a whole,
otherwise.</p>
<p>For <code>link</code> elements, the <code
title="rel-author">author</code> keyword indicates that the
referenced document provides further information about the author
for the page as a whole.</p>
<p class="note">The "referenced document" can be, and often is, a
<code title="">mailto:</code> URL giving the e-mail address of the
author. <a href="#refsMAILTO">[MAILTO]</a></p>
<div class="impl">
<p><strong>Synonyms</strong>: For historical reasons, user agents
must also treat <code>link</code>, <code>a</code>, and
<code>area</code> elements that have a <code title="">rev</code>
attribute with the value "<code>made</code>" as having the <code
title="rel-author">author</code> keyword specified as a link
relationship.</p>
</div>
<h5>Link type "<dfn title="rel-bookmark"><code>bookmark</code></dfn>"</h5>
<p>The <code title="rel-bookmark">bookmark</code> keyword may be
used with <code>a</code> and <code>area</code> elements.</p>
<p>The <code title="rel-bookmark">bookmark</code> keyword gives a
permalink for the nearest ancestor <code>article</code> element of
the linking element in question, or of <a
href="#associatedSection">the section the linking element is most
closely associated with</a>, if there are no ancestor
<code>article</code> elements.</p>
<div class="example">
<p>The following snippet has three permalinks. A user agent could
determine which permalink applies to which part of the spec by
looking at where the permalinks are given.</p>
<pre> ...
<body>
<h1>Example of permalinks</h1>
<div id="a">
<h2>First example</h2>
<p><a href="a.html" rel="bookmark">This</a> permalink applies to
only the content from the first H2 to the second H2. The DIV isn't
exactly that section, but it roughly corresponds to it.</p>
</div>
<h2>Second example</h2>
<article id="b">
<p><a href="b.html" rel="bookmark">This</a> permalink applies to
the outer ARTICLE element (which could be, e.g., a blog post).</p>
<article id="c">
<p><a href="c.html" rel="bookmark">This</a> permalink applies to
the inner ARTICLE element (which could be, e.g., a blog comment).</p>
</article>
</article>
</body>
...</pre>
</div>
<!-- (commented out on the assumption that rel=contact is really XFN)
<h5>Link type "<dfn title="rel-contact"><code>contact</code></dfn>"</h5>
<p>The <code title="rel-contact">contact</code> keyword may be used
with <code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>For <code>a</code> and <code>area</code> elements, the <code
title="rel-contact">contact</code> keyword indicates that the
referenced document provides further contact information for the
author of the nearest <code>article</code> element ancestor of the
element defining the hyperlink, if there is one, or of the page as a
whole, otherwise.</p>
<div class="impl">
<p>User agents must treat any hyperlink in an <code>address</code>
element as having the <code title="rel-contact">contact</code> link
type specified.</p>
</div>
<p>For <code>link</code> elements, the <code
title="rel-contact">contact</code> keyword indicates that the
referenced document provides further contact information for the
page as a whole.</p>
-->
<h5>Link type "<dfn title="rel-external"><code>external</code></dfn>"</h5>
<p>The <code title="rel-external">external</code> keyword may be
used with <code>a</code> and <code>area</code> elements.</p>
<p>The <code title="rel-external">external</code> keyword indicates
that the link is leading to a document that is not part of the site
that the current document forms a part of.</p>
<h5>Link type "<dfn title="rel-help"><code>help</code></dfn>"</h5>
<p>The <code title="rel-help">help</code> keyword may be used with
<code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>For <code>a</code> and <code>area</code> elements, the <code
title="rel-help">help</code> keyword indicates that the referenced
document provides further help information for the parent of the
element defining the hyperlink, and its children.</p>
<div class="example">
<p>In the following example, the form control has associated
context-sensitive help. The user agent could use this information,
for example, displaying the referenced document if the user presses
the "Help" or "F1" key.</p>
<pre> <p><label> Topic: <input name=topic> <a href="help/topic.html" rel="help">(Help)</a></label></p></pre>
</div>
<p>For <code>link</code> elements, the <code
title="rel-help">help</code> keyword indicates that the referenced
document provides help for the page as a whole.</p>
<h5 id=rel-icon>Link type "<dfn title="rel-icon"><code>icon</code></dfn>"</h5>
<p>The <code title="rel-icon">icon</code> keyword may be used with
<code>link</code> elements, for which it creates an <span
title="external resource link">external resource link</span>.</p>
<div class="impl">
<p>The specified resource is an icon representing the page or site,
and should be used by the user agent when representing the page in
the user interface.</p>
</div>
<p>Icons could be auditory icons, visual icons, or other kinds of
icons. <span class="impl">If multiple icons are provided, the user
agent must select the most appropriate icon according to the <code
title="attr-link-type">type</code>, <code
title="attr-link-media">media</code>, and <code
title="attr-link-sizes">sizes</code> attributes. If there are
multiple equally appropriate icons, user agents must use the last
one declared in <span>tree order</span>. If the user agent tries to
use an icon but that icon is determined, upon closer examination, to
in fact be inappropriate (e.g. because it uses an unsupported
format), then the user agent must try the next-most-appropriate icon
as determined by the attributes.</span></p>
<div class="impl">
<p>There is no default type for resources given by the <code
title="rel-icon">icon</code> keyword. However, for the purposes of
<a href="#concept-link-type-sniffing">determining the type of the
resource</a>, user agents must expect the resource to be an image.</p>
</div>
<p>The <dfn title="attr-link-sizes"><code>sizes</code></dfn>
attribute gives the sizes of icons for visual media.</p>
<p>If specified, the attribute must have a value that is an
<span>unordered set of unique space-separated tokens</span>. The
values must all be either <code
title="attr-link-sizes-any">any</code> or a value that consists of
two <span title="valid non-negative integer">valid non-negative
integers</span> that do not have a leading U+0030 DIGIT ZERO (0)
character and that are separated by a single U+0078 LATIN SMALL
LETTER X character (x).</p>
<p>The keywords represent icon sizes.</p>
<div class="impl">
<p>To parse and process the attribute's value, the user agent must
first <span title="split a string on spaces">split the attribute's
value on spaces</span>, and must then parse each resulting keyword
to determine what it represents.</p>
</div>
<p>The <dfn title="attr-link-sizes-any"><code>any</code></dfn> keyword
represents that the resource contains a scalable icon, e.g. as
provided by an SVG image.</p>
<div class="impl">
<p>Other keywords must be further parsed as follows to determine
what they represent:</p>
<ul>
<li><p>If the keyword doesn't contain exactly one U+0078 LATIN
SMALL LETTER X character (x), then this keyword doesn't represent
anything. Abort these steps for that keyword.</p></li>
<li><p>Let <var title="">width string</var> be the string before
the "<code title="">x</code>".</p></li>
<li><p>Let <var title="">height string</var> be the string after the
"<code title="">x</code>".</p></li>
<li><p>If either <var title="">width string</var> or <var
title="">height string</var> start with a U+0030 DIGIT ZERO (0)
character or contain any characters other than characters in the
range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then this
keyword doesn't represent anything. Abort these steps for that
keyword.</p></li>
<li><p>Apply the <span>rules for parsing non-negative
integers</span> to <var title="">width string</var> to obtain <var
title="">width</var>.</p></li>
<li><p>Apply the <span>rules for parsing non-negative
integers</span> to <var title="">height string</var> to obtain <var
title="">height</var>.</p></li>
<li><p>The keyword represents that the resource contains a bitmap
icon with a width of <var title="">width</var> device pixels and a
height of <var title="">height</var> device pixels.</p></li>
</ul>
</div>
<p>The keywords specified on the <code
title="attr-link-sizes">sizes</code> attribute must not represent
icon sizes that are not actually available in the linked
resource.</p>
<div class="impl">
<p>If the attribute is not specified, then the user agent must
assume that the given icon is appropriate, but less appropriate than
an icon of a known and appropriate size.</p>
</div>
<div class="example">
<p>The following snippet shows the top part of an application with
several icons.</p>
<pre><!DOCTYPE HTML>
<html>
<head>
<title>lsForums — Inbox</title>
<link rel=icon href=favicon.png sizes="16x16">
<link rel=icon href=windows.ico sizes="32x32 48x48">
<link rel=icon href=mac.icns sizes="128x128 512x512 8192x8192 32768x32768">
<link rel=icon href=iphone.png sizes="59x60">
<link rel=icon href=gnome.svg sizes="any">
<link rel=stylesheet href=lsforums.css>
<script src=lsforums.js></script>
<meta name=application-name content="lsForums">
</head>
<body>
...</pre>
</div>
<h5>Link type "<dfn title="rel-license"><code>license</code></dfn>"</h5>
<p>The <code title="rel-license">license</code> keyword may be used
with <code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-license">license</code> keyword indicates
that the referenced document provides the copyright license terms
under which the main content of the current document is
provided.</p>
<p>This specification does not specify how to distinguish between
the main content of a document and content that is not deemed to be
part of that main content. The distinction should be made clear to
the user.</p>
<div class="example">
<p>Consider a photo sharing site. A page on that site might
describe and show a photograph, and the page might be marked up as
follows:</p>
<pre><!DOCTYPE HTML>
<html>
<head>
<title>Exampl Pictures: Kissat</title>
<link rel="stylesheet" href="/style/default">
</head>
<body>
<h1>Kissat</h1>
<nav>
<a href="../">Return to photo index</a>
</nav>
<figure>
<dd><img src="/pix/39627052_fd8dcd98b5.jpg">
<dt>Kissat
</figure>
<p>One of them has six toes!</p>
<p><small><a rel="license" href="http://www.opensource.org/licenses/mit-license.php">MIT Licensed</a></small></p>
<footer>
<a href="/">Home</a> | <a href="../">Photo index</a>
<p><small>© copyright 2009 Exampl Pictures. All Rights Reserved.</small></p>
</footer>
</body>
</html></pre>
<p>In this case the <code title="rel-license">license</code>
applies to just the photo (the main content of the document), not
the whole document. In particular not the design of the page
itself, which is covered by the copyright given at the bottom of
the document. This could be made clearer in the styling
(e.g. making the license link prominently positioned near the
photograph, while having the page copyright in light small text at
the foot of the page.</p>
</div>
<div class="impl">
<p><strong>Synonyms</strong>: For historical reasons, user agents
must also treat the keyword "<code title="">copyright</code>" like
the <code title="rel-license">license</code> keyword.</p>
</div>
<h5>Link type "<dfn title="rel-nofollow"><code>nofollow</code></dfn>"</h5>
<p>The <code title="rel-nofollow">nofollow</code> keyword may be
used with <code>a</code> and <code>area</code> elements.</p>
<p>The <code title="rel-nofollow">nofollow</code> keyword indicates
that the link is not endorsed by the original author or publisher of
the page, or that the link to the referenced document was included
primarily because of a commercial relationship between people
affiliated with the two pages.</p>
<h5>Link type "<dfn title="rel-noreferrer"><code>noreferrer</code></dfn>"</h5>
<p>The <code title="rel-noreferrer">noreferrer</code> keyword may be
used with <code>a</code> and <code>area</code> elements.</p>
<p>It indicates that no referrer information is to be leaked when
following the link.</p>
<div class="impl">
<p>If a user agent follows a link defined by an <code>a</code> or
<code>area</code> element that has the <code
title="rel-noreferrer">noreferrer</code> keyword, the user agent
must not include a <code title="">Referer</code> (sic) HTTP header
(<span title="concept-http-equivalent-headers">or equivalent</span>
for other protocols) in the request.</p>
<p>This keyword also <a href="#noopener">causes the <code
title="dom-opener">opener</code> attribute to remain null</a> if the
hyperlink creates a new <span>browsing context</span>.</p>
</div>
<!-- v2: Would be nice to apply this to other elements too,
e.g. letting <img> or CSS or <video> hide the referrer -->
<h5>Link type "<dfn title="rel-pingback"><code>pingback</code></dfn>"</h5>
<p>The <code title="rel-pingback">pingback</code> keyword may be
used with <code>link</code> elements, for which it creates an <span
title="external resource link">external resource link</span>.</p>
<p>For the semantics of the <code
title="rel-pingback">pingback</code> keyword, see the Pingback 1.0
specification. <a href="#refsPINGBACK">[PINGBACK]</a></p>
<h5>Link type "<dfn title="rel-prefetch"><code>prefetch</code></dfn>"</h5>
<p>The <code title="rel-prefetch">prefetch</code> keyword may be
used with <code>link</code> elements, for which it creates an <span
title="external resource link">external resource link</span>.</p>
<p>The <code title="rel-prefetch">prefetch</code> keyword indicates
that preemptively fetching and caching the specified resource is
likely to be beneficial, as it is highly likely that the user will
require this resource.</p>
<p>There is no default type for resources given by the <code
title="rel-prefetch">prefetch</code> keyword.</p>
<h5>Link type "<dfn title="rel-search"><code>search</code></dfn>"</h5>
<p>The <code title="rel-search">search</code> keyword may be used
with <code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-search">search</code> keyword indicates that
the referenced document provides an interface specifically for
searching the document and its related resources.</p>
<p class="note">OpenSearch description documents can be used with
<code>link</code> elements and the <code
title="rel-search">search</code> link type to enable user agents to
autodiscover search interfaces. <a
href="#refsOPENSEARCH">[OPENSEARCH]</a></p>
<h5>Link type "<dfn title="rel-stylesheet"><code>stylesheet</code></dfn>"</h5>
<p>The <code title="rel-stylesheet">stylesheet</code> keyword may be
used with <code>link</code> elements, for which it creates an <span
title="external resource link">external resource link</span> that
contributes to the <span>styling processing model</span>.</p>
<p>The specified resource is a resource that describes how to
present the document. Exactly how the resource is to be processed
depends on the actual type of the resource.</p>
<p>If the <code title="rel-alternate">alternate</code> keyword is
also specified on the <code>link</code> element, then <dfn>the link
is an alternative stylesheet</dfn>; in this case, the <code
title="attr-title">title</code> attribute must be specified on the
<code>link</code> element, with a non-empty value.</p>
<p>The default type for resources given by the <code
title="rel-stylesheet">stylesheet</code> keyword is <code
title="">text/css</code>.</p>
<div class="impl">
<p><strong>Quirk</strong>: If the document has been set to
<span>quirks mode</span> and the <span
title="Content-Type">Content-Type metadata</span> of the external
resource is not a supported style sheet type, the user agent must
instead assume it to be <code title="">text/css</code>.</p>
</div>
<h5>Link type "<dfn title="rel-sidebar"><code>sidebar</code></dfn>"</h5>
<p>The <code title="rel-sidebar">sidebar</code> keyword may be used
with <code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-sidebar">sidebar</code> keyword indicates
that the referenced document, if retrieved, is intended to be shown
in a <span>secondary browsing context</span> (if possible), instead
of in the current <span>browsing context</span>.</p>
<p>A <span title="hyperlink">hyperlink element</span> with the <code
title="rel-sidebar">sidebar</code> keyword specified is a <dfn
title="rel-sidebar-hyperlink">sidebar hyperlink</dfn>.</p>
<h5>Link type "<dfn title="rel-tag"><code>tag</code></dfn>"</h5>
<p>The <code title="rel-tag">tag</code> keyword may be used
with <code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-tag">tag</code> keyword indicates that the
<em>tag</em> that the referenced document represents applies to the
current document.</p>
<p class="note">Since it indicates that the tag <em>applies to the
current document</em>, it would be inappropriate to use this keyword
in the markup of a <a href="#tag-cloud">tag cloud</a>, which lists
the popular tag across a set of pages.</p>
<h5>Hierarchical link types</h5>
<p>Some documents form part of a hierarchical structure of
documents.</p>
<p>A hierarchical structure of documents is one where each document
can have various subdocuments. The document of which a document is a
subdocument is said to be the document's <em>parent</em>. A document
with no parent forms the top of the hierarchy.</p>
<p>A document may be part of multiple hierarchies.</p>
<h6>Link type "<dfn title="rel-index"><code>index</code></dfn>"</h6>
<p>The <code title="rel-index">index</code> keyword may be used with
<code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-index">index</code> keyword indicates that
the document is part of a hierarchical structure, and that the link
is leading to the document that is the top of the hierarchy. It
conveys more information when used with the <code
title="rel-up">up</code> keyword (q.v.).</p>
<div class="impl">
<p><strong>Synonyms</strong>: For historical reasons, user agents
must also treat the keywords "<code title="">top</code>", "<code
title="">contents</code>", and "<code title="">toc</code>" like the
<code title="rel-index">index</code> keyword.</p>
</div>
<h6>Link type "<dfn title="rel-up"><code>up</code></dfn>"</h6>
<p>The <code title="rel-up">up</code> keyword may be used with
<code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-up">up</code> keyword indicates that the
document is part of a hierarchical structure, and that the link is
leading to a document that is an ancestor of the current
document.</p>
<p>The <code title="rel-up">up</code> keyword may be repeated within
a <code title="attr-hyperlink-rel">rel</code> attribute to indicate
the hierarchical distance from the current document to the
referenced document. If it occurs only once, then the link is
leading to the current document's parent; each additional occurrence
of the keyword represents one further level. If the <code
title="rel-index">index</code> keyword is also present, then the
number of <code title="rel-up">up</code> keywords is the depth of
the current page relative to the top of the hierarchy. Only one link
is created for the set of one or more <code title="rel-up">up</code>
keywords and, if present, the <code title="rel-index">index</code>
keyword.</p>
<p>If the page is part of multiple hierarchies, then they should be
described in different <span
title="paragraph">paragraphs</span>. <span class="impl">User agents
must scope any interpretation of the <code title="rel-up">up</code>
and <code title="rel-index">index</code> keywords together
indicating the depth of the hierarchy to the <span>paragraph</span>
in which the link finds itself, if any, or to the document
otherwise.</span></p>
<div class="impl">
<p>When two links have both the <code title="rel-up">up</code> and
<code title="rel-index">index</code> keywords specified together in
the same scope and contradict each other by having a different
number of <code title="rel-up">up</code> keywords, the link with the
greater number of <code title="rel-up">up</code> keywords must be
taken as giving the depth of the document.</p>
</div>
<div class="example">
<p>This can be used to mark up a navigation style sometimes known
as bread crumbs. In the following example, the current page can be
reached via two paths.</p>
<pre><nav>
<p>
<a href="/" rel="index up up up">Main</a> >
<a href="/products/" rel="up up">Products</a> >
<a href="/products/dishwashers/" rel="up">Dishwashers</a> >
<a>Second hand</a>
</p>
<p>
<a href="/" rel="index up up">Main</a> >
<a href="/second-hand/" rel="up">Second hand</a> >
<a>Dishwashers</a>
</p>
</nav></pre>
</div>
<p class="note">The <code title="dom-a-relList">relList</code> IDL
attribute (e.g. on the <code>a</code> element) does not currently
represent multiple <code title="rel-up">up</code> keywords (the
interface hides duplicates).</p>
<h5>Sequential link types</h5>
<p>Some documents form part of a sequence of documents.</p>
<p>A sequence of documents is one where each document can have a
<em>previous sibling</em> and a <em>next sibling</em>. A document
with no previous sibling is the start of its sequence, a document
with no next sibling is the end of its sequence.</p>
<p>A document may be part of multiple sequences.</p>
<h6>Link type "<dfn title="rel-first"><code>first</code></dfn>"</h6>
<p>The <code title="rel-first">first</code> keyword may be used with
<code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-first">first</code> keyword indicates that
the document is part of a sequence, and that the link is leading to
the document that is the first logical document in the sequence.</p>
<div class="impl">
<p><strong>Synonyms</strong>: For historical reasons, user agents
must also treat the keywords "<code title="">begin</code>" and
"<code title="">start</code>" like the <code
title="rel-first">first</code> keyword.</p>
</div>
<h6>Link type "<dfn title="rel-last"><code>last</code></dfn>"</h6>
<p>The <code title="rel-last">last</code> keyword may be used with
<code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-last">last</code> keyword indicates that the
document is part of a sequence, and that the link is leading to the
document that is the last logical document in the sequence.</p>
<div class="impl">
<p><strong>Synonyms</strong>: For historical reasons, user agents
must also treat the keyword "<code title="">end</code>" like the
<code title="rel-last">last</code> keyword.</p>
</div>
<h6>Link type "<dfn title="rel-next"><code>next</code></dfn>"</h6>
<p>The <code title="rel-next">next</code> keyword may be used with
<code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-next">next</code> keyword indicates that the
document is part of a sequence, and that the link is leading to the
document that is the next logical document in the sequence.</p>
<h6>Link type "<dfn title="rel-prev"><code>prev</code></dfn>"</h6>
<p>The <code title="rel-prev">prev</code> keyword may be used with
<code>link</code>, <code>a</code>, and <code>area</code>
elements. For <code>link</code> elements, it creates a <span
title="hyperlink link">hyperlink</span>.</p>
<p>The <code title="rel-prev">prev</code> keyword indicates that the
document is part of a sequence, and that the link is leading to the
document that is the previous logical document in the sequence.</p>
<div class="impl">
<p><strong>Synonyms</strong>: For historical reasons, user agents
must also treat the keyword "<code title="">previous</code>" like
the <code title="rel-prev">prev</code> keyword.</p>
</div>
<h5>Other link types</h5>
<p><dfn title="concept-rel-extensions">Extensions to the predefined
set of link types</dfn> may be registered in the <a
href="http://wiki.whatwg.org/wiki/RelExtensions">WHATWG Wiki
RelExtensions page</a>. <a
href="#refsWHATWGWIKI">[WHATWGWIKI]</a></p>
<p>Anyone is free to edit the WHATWG Wiki RelExtensions page at any
time to add a type. Extension types must be specified with the
following information:</p>
<dl>
<dt>Keyword</dt>
<dd><p>The actual value being defined. The value should not be
confusingly similar to any other defined value (e.g. differing only
in case).</p></dd>
<dt>Effect on... <code>link</code></dt>
<dd>
<p>One of the following:</p>
<dl>
<dt>not allowed</dt>
<dd>The keyword is not allowed to be specified on
<code>link</code> elements.</dd>
<dt>Hyperlink</dt>
<dd>The keyword may be specified on a <code>link</code> element;
it creates a <span title="hyperlink link">hyperlink
link</span>.</dd>
<dt>External Resource</dt>
<dd>The keyword may be specified on a <code>link</code> element;
it creates a <span title="external resource link">external
resource link</span>.</dd>
</dl>
</dd>
<dt>Effect on... <code>a</code> and <code>area</code></dt>
<dd>
<p>One of the following:</p>
<dl>
<dt>not allowed</dt>
<dd>The keyword is not allowed to be specified on <code>a</code>
and <code>area</code> elements.</dd>
<dt>Hyperlink</dt>
<dd>The keyword may be specified on <code>a</code> and
<code>area</code> elements.</dd>
</dl>
</dd>
<dt>Brief description</dt>
<dd><p>A short non-normative description of what the keyword's
meaning is.</p></dd>
<dt>Specification</dt>
<dd><p>A link to a more detailed description of the keyword's
semantics and requirements. It could be another page on the Wiki,
or a link to an external page.</p></dd>
<dt>Synonyms</dt>
<dd><p>A list of other keyword values that have exactly the same
processing requirements. Authors should not use the values defined
to be synonyms, they are only intended to allow user agents to
support legacy content. Anyone may remove synonyms that are not
used in practice; only names that need to be processed as synonyms
for compatibility with legacy content are to be registered in this
way.</p></dd>
<dt>Status</dt>
<dd>
<p>One of the following:</p>
<dl>
<dt>Proposed</dt>
<dd>The keyword has not received wide peer review and
approval. Someone has proposed it and is, or soon will be, using
it.</dd>
<dt>Ratified</dt>
<dd>The keyword has received wide peer review and approval. It
has a specification that unambiguously defines how to handle
pages that use the keyword, including when they use it in
incorrect ways.</dd>
<dt>Discontinued</dt>
<dd>The keyword has received wide peer review and it has been
found wanting. Existing pages are using this keyword, but new
pages should avoid it. The "brief description" and
"specification" entries will give details of what authors should
use instead, if anything.</dd>
</dl>
<p>If a keyword is found to be redundant with existing values, it
should be removed and listed as a synonym for the existing
value.</p>
<p>If a keyword is registered in the "proposed" state for a
period of a month or more without being used or specified, then it
may be removed from the registry.</p>
<p>If a keyword is added with the "proposed" status and found to
be redundant with existing values, it should be removed and listed
as a synonym for the existing value. If a keyword is added with
the "proposed" status and found to be harmful, then it should be
changed to "discontinued" status.</p>
<p>Anyone can change the status at any time, but should only do so
in accordance with the definitions above.</p>
</dd>
</dl>
<div class="impl">
<p>Conformance checkers must use the information given on the WHATWG
Wiki RelExtensions page to establish if a value is allowed or not:
values defined in this specification or marked as "proposed" or
"ratified" must be accepted when used on the elements for which they
apply as described in the "Effect on..." field, whereas values
marked as "discontinued" or not listed in either this specification
or on the aforementioned page must be rejected as invalid.
Conformance checkers may cache this information (e.g. for
performance reasons or to avoid the use of unreliable network
connectivity).</p>
<p>When an author uses a new type not defined by either this
specification or the Wiki page, conformance checkers should offer to
add the value to the Wiki, with the details described above, with
the "proposed" status.</p>
</div>
<p>Types defined as extensions in the <a
href="http://wiki.whatwg.org/wiki/RelExtensions">WHATWG Wiki
RelExtensions page</a> with the status "proposed" or "ratified" may
be used with the <code title="">rel</code> attribute on
<code>link</code>, <code>a</code>, and <code>area</code> elements in
accordance to the "Effect on..." field. <a
href="#refsWHATWGWIKI">[WHATWGWIKI]</a></p>
<!--END html--><!--END html5-->
<!--END complete-->
<h2 id="storage-and-database">Structured client-side storage APIs</h2>
<!--START complete-->
<!--FIXUP -1-->
<h3 id="webstorage">Web Storage</h3>
<!--START storage-->
<h4>Introduction</h4>
<p><i>This section is non-normative.</i></p>
<p>This specification introduces two related mechanisms, similar to
HTTP session cookies, for storing structured data on the client
side. <a href="#refsCOOKIES">[COOKIES]</a></p>
<p>The first is designed for scenarios where the user is carrying
out a single transaction, but could be carrying out multiple
transactions in different windows at the same time.</p>
<p>Cookies don't really handle this case well. For example, a user
could be buying plane tickets in two different windows, using the
same site. If the site used cookies to keep track of which ticket
the user was buying, then as the user clicked from page to page in
both windows, the ticket currently being purchased would "leak" from
one window to the other, potentially causing the user to buy two
tickets for the same flight without really noticing.</p>
<p>To address this, this specification introduces the <code
title="dom-sessionStorage">sessionStorage</code> IDL attribute.
Sites can add data to the session storage, and it will be accessible
to any page from the same site opened in that window.</p> <!-- we're
not using xrefs here because this is just an intro -->
<div class="example">
<p>For example, a page could have a checkbox that the user ticks to
indicate that he wants insurance:</p>
<pre><label>
<input type="checkbox" onchange="sessionStorage.insurance = checked">
I want insurance on this trip.
</label></pre>
<p>A later page could then check, from script, whether the user had
checked the checkbox or not:</p>
<pre>if (sessionStorage.insurance) { ... }</pre>
<p>If the user had multiple windows opened on the site, each one
would have its own individual copy of the session storage object.</p>
</div>
<!--
sessionStorage.flightDeparture = 'OSL';
sessionStorage.flightArrival = 'NYC';
for (var i in forms[0].elements)
sessionStorage["data_" + i.name] = i.value;
if (!sessionStorage[documents])
sessionStorage[documents] = {};
sessionStorage[documents][filename] = <document/>;
-->
<p>The second storage mechanism is designed for storage that spans
multiple windows, and lasts beyond the current session. In
particular, Web applications may wish to store megabytes of user
data, such as entire user-authored documents or a user's mailbox, on
the client side for performance reasons.</p>
<p>Again, cookies do not handle this case well, because they are
transmitted with every request.</p>
<p>The <code title="dom-localStorage">localStorage</code> IDL
attribute is used to access a page's local storage area.</p>
<div class="example">
<p>The site at example.com can display a count of how many times
the user has loaded its page by putting the following at the bottom
of its page:</p>
<pre><p>
You have viewed this page
<span id="count">an untold number of</span>
time(s).
</p>
<script>
if (!localStorage.pageLoadCount)
localStorage.pageLoadCount = 0;
localStorage.pageLoadCount += 1;
document.getElementById('count').textContent = localStorage.pageLoadCount;
</script></pre>
</div>
<p>Each site has its own separate storage area.</p>
<!--END complete-->
<!--BOILERPLATE middle-w3c-api-intro-->
<!--BOILERPLATE middle-w3c-js-disclaimer-->
<!--START complete-->
<h4 id="storage">The API</h4>
<h5>The <code>Storage</code> interface</h5>
<pre class="idl">interface <dfn>Storage</dfn> {
readonly attribute unsigned long <span title="dom-Storage-length">length</span>;
getter DOMString <span title="dom-Storage-key">key</span>(in unsigned long index);
getter any <span title="dom-Storage-getItem">getItem</span>(in DOMString key);
setter creator void <span title="dom-Storage-setItem">setItem</span>(in DOMString key, in any data);
deleter void <span title="dom-Storage-removeItem">removeItem</span>(in DOMString key);
void <span title="dom-Storage-clear">clear</span>();
};</pre>
<!-- v2 ideas:
a getInfo() method that returns an object that tells you:
- when the key was added
- when the key was last modified
- which page was the last to modify the key
[-Mihai Sucan]
-->
<p>Each <code>Storage</code> object provides access to a list of
key/value pairs, which are sometimes called items. Keys are
strings. Any string (including the empty string) is a valid
key. Values can be any data type supported by the <span>structured
clone</span> algorithm.</p>
<p>Each <code>Storage</code> object is associated with a list of
key/value pairs when it is created, as defined in the sections on
the <code title="dom-sessionStorage">sessionStorage</code> and <code
title="dom-localStorage">localStorage</code> attributes. Multiple
separate objects implementing the <code>Storage</code> interface can
all be associated with the same list of key/value pairs
simultaneously.</p>
<p>The object's <span>indices of the supported indexed
properties</span> are the numbers in the range zero to one less than
the number of key/value pairs currently present in the list
associated with the object. If the list is empty, then there are no
<span>supported indexed properties</span>.</p>
<p>The <dfn title="dom-Storage-length"><code>length</code></dfn>
attribute must return the number of key/value pairs currently
present in the list associated with the object.</p>
<p>The <dfn title="dom-Storage-key"><code>key(<var
title="">n</var>)</code></dfn> method must return the name of the
<var title="">n</var>th key in the list. The order of keys is
user-agent defined, but must be consistent within an object so long
as the number of keys doesn't change. (Thus, <span
title="dom-Storage-setItem">adding</span> or <span
title="dom-Storage-removeItem">removing</span> a key may change the
order of the keys, but merely changing the value of an existing key
must not.) <!--The order of keys may differ between instances of the
<code>Storage</code> interface accessing the same list. [removed for
now for clarity, but if people ask, put it back. this is part of the
spec.]--> If <var title="">n</var> is <!--less than zero or [can't,
unsigned]--> greater than or equal to the number of key/value pairs
in the object, then this method must return null.</p>
<p>The <span>names of the supported named properties</span> on a
<code>Storage</code> object are the keys of each key/value pair
currently present in the list associated with the object.</p>
<p>The <dfn title="dom-Storage-getItem"><code>getItem(<var
title="">key</var>)</code></dfn> method must return a
<span>structured clone</span> of the current value associated with
the given <var title="">key</var>. If the given <var
title="">key</var> does not exist in the list associated with the
object then this method must return null.</p>
<p>The <dfn title="dom-Storage-setItem"><code>setItem(<var
title="">key</var>, <var title="">value</var>)</code></dfn> method
must first create a <span>structured clone</span> of the given <var
title="">value</var>. If this raises an exception, then the
exception must be thrown and the list associated with the object is
left unchanged. If constructing the stuctured clone would involve
constructing a new <code>ImageData</code> object, then throw a
<code>NOT_SUPPORTED_ERR</code> exception instead.</p>
<!-- ImageData isn't supported because reading such objects is
synchronous, and getData() is synchronous, and therefore if the
stored data is in deep storage, it would be very painful to have a
script grab the value and immediately try to read the image
data. -->
<p>Otherwise, the user agent must then check if a key/value pair
with the given <var title="">key</var> already exists in the list
associated with the object.</p>
<p>If it does not, then a new key/value pair must be added to the
list, with the given <var title="">key</var> and with its value set
to the newly obtained clone of <var title="">value</var>.</p>
<p>If the given <var title="">key</var> <em>does</em> exist in the
list, then it must have its value updated to the newly obtained
clone of <var title="">value</var>.</p>
<p>If it couldn't set the new value, the method must raise an
<code>QUOTA_EXCEEDED_ERR</code> exception. (Setting could fail if,
e.g., the user has disabled storage for the site, or if the quota
has been exceeded.)</p>
<p>The <dfn title="dom-Storage-removeItem"><code>removeItem(<var
title="">key</var>)</code></dfn> method must cause the key/value
pair with the given <var title="">key</var> to be removed from the
list associated with the object, if it exists. If no item with that
key exists, the method must do nothing.</p>
<p>The <code title="dom-Storage-setItem">setItem()</code> and <code
title="dom-Storage-removeItem">removeItem()</code> methods must be
atomic with respect to failure. In the case of failure, the method
does nothing. That is, changes to the data storage area must either
be successful, or the data storage area must not be changed at
all.</p>
<p>The <dfn title="dom-Storage-clear"><code>clear()</code></dfn>
method must atomically cause the list associated with the object to
be emptied of all key/value pairs, if there are any. If there are
none, then the method must do nothing.</p>
<p class="note">When the <code
title="dom-Storage-setItem">setItem()</code>, <code
title="dom-Storage-removeItem">removeItem()</code>, and <code
title="dom-Storage-clear">clear()</code> methods are invoked, events
are fired on other <code>HTMLDocument</code> objects that can access
the newly stored or removed data, as defined in the sections on the
<code title="dom-sessionStorage">sessionStorage</code> and <code
title="dom-localStorage">localStorage</code> attributes.</p> <!--
not normative, see the sections below for the normative statement
-->
<p class="note">This specification does not require that the above
methods wait until the data has been physically written to
disk. Only consistency in what different scripts accessing the same
underlying list of key/value pairs see is required.</p>
<h5>The <code title="dom-sessionStorage">sessionStorage</code> attribute</h5>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <span>WindowSessionStorage</span> {
readonly attribute <span>Storage</span> <span title="dom-sessionStorage">sessionStorage</span>;
};
<span>Window</span> implements <span>WindowSessionStorage</span>;</pre>
<p>The <dfn
title="dom-sessionStorage"><code>sessionStorage</code></dfn>
attribute represents the set of storage areas specific to the
current <span>top-level browsing context</span>.</p>
<p>Each <span>top-level browsing context</span> has a unique set of
session storage areas, one for each <span>origin</span>.</p>
<p>User agents should not expire data from a browsing context's
session storage areas, but may do so when the user requests that
such data be deleted, or when the UA detects that it has limited
storage space, or for security reasons. User agents should always
avoid deleting data while a script that could access that data is
running. When a top-level browsing context is destroyed (and
therefore permanently inaccessible to the user) the data stored in
its session storage areas can be discarded with it, as the API
described in this specification provides no way for that data to
ever be subsequently retrieved.</p>
<p class="note">The lifetime of a browsing context can be unrelated
to the lifetime of the actual user agent process itself, as the user
agent may support resuming sessions after a restart.</p>
<p>When a new <code>HTMLDocument</code> is created, the user agent
must check to see if the document's <span>top-level browsing
context</span> has allocated a session storage area for that
document's <span>origin</span>. If it has not, a new storage area
for that document's <span>origin</span> must be created.</p>
<p>The <code title="dom-sessionStorage">sessionStorage</code>
attribute must return the <code>Storage</code> object associated
with that session storage area. Each <code>Document</code> object
must have a separate object for its <code>Window</code>'s <code
title="dom-sessionStorage">sessionStorage</code> attribute.</p>
<p>When a new <span>top-level browsing context</span> is created by
cloning an existing <span>browsing context</span>, the new browsing
context must start with the same session storage areas as the
original, but the two sets must from that point on be considered
separate, not affecting each other in any way.</p>
<p>When a new <span>top-level browsing context</span> is created by
a <span title="concept-script">script</span> in an existing
<span>browsing context</span>, or by the user following a link in an
existing browsing context, or in some other way related to a
specific <code>HTMLDocument</code>, then the session storage area of
the <span>origin</span> of that <code>HTMLDocument</code> must be
copied into the new browsing context when it is created. From that
point on, however, the two session storage areas must be considered
separate, not affecting each other in any way.</p>
<p id="sessionStorageEvent">When the <code
title="dom-Storage-setItem">setItem()</code>, <code
title="dom-Storage-removeItem">removeItem()</code>, and <code
title="dom-Storage-clear">clear()</code> methods are called on a
<code>Storage</code> object <var title="">x</var> that is associated
with a session storage area, if the methods did something, then in
every <code>HTMLDocument</code> object whose <code>Window</code>
object's <code title="dom-sessionStorage">sessionStorage</code>
attribute's <code>Storage</code> object is associated with the same
storage area, other than <var title="">x</var>, a <code
title="event-storage">storage</code> event must be fired, as <span
title="event-storage">described below</span>.</p>
<h5>The <code title="dom-localStorage">localStorage</code> attribute</h5>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <span>WindowLocalStorage</span> {
readonly attribute <span>Storage</span> <span title="dom-localStorage">localStorage</span>;
};
<span>Window</span> implements <span>WindowLocalStorage</span>;</pre>
<p>The <dfn title="dom-localStorage"><code>localStorage</code></dfn>
object provides a <code>Storage</code> object for an
<span>origin</span>.</p>
<p>User agents must have a set of local storage areas, one for each
<span>origin</span>.</p>
<p>User agents should expire data from the local storage areas only
for security reasons or when requested to do so by the user. User
agents should always avoid deleting data while a script that could
access that data is running.</p>
<p>When the <code title="dom-localStorage">localStorage</code>
attribute is accessed, the user agent must run the following steps:</p>
<ol>
<li><p>The user agent may raise a <code>SECURITY_ERR</code>
exception instead of returning a <code>Storage</code> object if the
request violates a policy decision (e.g. if the user agent is
configured to not allow the page to persist data).</p></li>
<li><p>If the <code>Document</code>'s <span>effective script
origin</span> is not the <span>same origin</span> as the
<code>Document</code>'s <span>origin</span>, then throw a
<code>SECURITY_ERR</code> exception and abort these steps.</p></li>
<li><p>Check to see if the user agent has allocated a local storage
area for the <span>origin</span> of the <code>Document</code> of
the <code>Window</code> object on which the method was invoked. If
it has not, create a new storage area for that
<span>origin</span>.</p></li>
<li><p>Return the <code>Storage</code> object associated with that
origin's local storage area. Each <code>Document</code> object must
have a separate object for its <code>Window</code>'s <code
title="dom-localStorage">localStorage</code> attribute.</p>
</ol>
<p id="localStorageEvent">When the <code
title="dom-Storage-setItem">setItem()</code>, <code
title="dom-Storage-removeItem">removeItem()</code>, and <code
title="dom-Storage-clear">clear()</code> methods are called on a
<code>Storage</code> object <var title="">x</var> that is associated
with a local storage area, if the methods did something, then in
every <code>HTMLDocument</code> object whose <code>Window</code>
object's <code title="dom-localStorage">localStorage</code>
attribute's <code>Storage</code> object is associated with the same
storage area, other than <var title="">x</var>, a <code
title="event-storage">storage</code> event must be fired, as <span
title="event-storage">described below</span>.</p>
<p id="localStorageMutex">Whenever the properties of a <code
title="dom-localStorage">localStorage</code> attribute's
<code>Storage</code> object are to be examined, returned, set, or
deleted, whether as part of a direct property access, when checking
for the presence of a property, during property enumeration, when
determining the number of properties present, or as part of the
execution of any of the methods or attributes defined on the
<code>Storage</code> interface. the user agent must first
<span>obtain the storage mutex</span>.</p>
<h5>The <code title="event-storage">storage</code> event</h5>
<p>The <dfn title="event-storage"><code>storage</code></dfn> event
is fired when a storage area changes, as described in the previous
two sections (<a href="#sessionStorageEvent">for session
storage</a>, <a href="#localStorageEvent">for local
storage</a>).</p>
<p>When this happens, the user agent must <span>queue a task</span>
to fire an event with the name <code>storage</code>, which does not
bubble and is not cancelable, and which uses the
<code>StorageEvent</code> interface, at each <code>Window</code>
object whose <code>Document</code> object has a <code>Storage</code>
object that is affected.</p>
<p class="note">This includes <code>Document</code> objects that are
not <span>fully active</span>, but events fired on those are ignored
by the <span>event loop</span> until the <code>Document</code>
becomes <span>fully active</span> again.</p>
<p>The <span>task source</span> for this task is the <span>DOM
manipulation task source</span>.</p>
<p>If the event is being fired due to an invocation of the <code
title="dom-Storage-setItem">setItem()</code> or <code
title="dom-Storage-removeItem">removeItem()</code> methods, the
event must have its <code title="dom-StorageEvent-key">key</code>
attribute set to the name of the key in question, its <code
title="dom-StorageEvent-oldValue">oldValue</code> attribute set to a
<span>structured clone</span> of the old value of the key in
question, or null if the key is newly added, and its <code
title="dom-StorageEvent-newValue">newValue</code> attribute set to a
<span>structured clone</span> of the new value of the key in
question, or null if the key was removed.</p>
<p>Otherwise, if the event is being fired due to an invocation of
the <code title="dom-Storage-clear">clear()</code> method, the event
must have its <code title="dom-StorageEvent-key">key</code>, <code
title="dom-StorageEvent-oldValue">oldValue</code>, and <code
title="dom-StorageEvent-newValue">newValue</code> attributes set to
null.</p>
<p>In addition, the event must have its <code
title="dom-StorageEvent-url">url</code> attribute set to <span
title="the document's address">the address of the document</span>
whose <code>Storage</code> object was affected; and its <code
title="dom-StorageEvent-storageArea">storageArea</code> attribute
set to the <code>Storage</code> object from the <code>Window</code>
object of the target <code>Document</code> that represents the same
kind of <code>Storage</code> area as was affected (i.e. session or
local).</p>
<h6>Event definition</h6>
<pre class="idl">interface <dfn>StorageEvent</dfn> : Event {
readonly attribute DOMString <span title="dom-StorageEvent-key">key</span>;
readonly attribute any <span title="dom-StorageEvent-oldValue">oldValue</span>;
readonly attribute any <span title="dom-StorageEvent-newValue">newValue</span>;
readonly attribute DOMString <span title="dom-StorageEvent-url">url</span>;
readonly attribute <span>Storage</span> <span title="dom-StorageEvent-storageArea">storageArea</span>;
void <span title="dom-StorageEvent-initStorageEvent">initStorageEvent</span>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString keyArg, in any oldValueArg, in any newValueArg, in DOMString urlArg, in <span>Storage</span> storageAreaArg);
};</pre>
<p>The <dfn
title="dom-StorageEvent-initStorageEvent"><code>initStorageEvent()</code></dfn>
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. <a
href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p>The <dfn title="dom-StorageEvent-key"><code>key</code></dfn>
attribute represents the key being changed.</p>
<p>The <dfn
title="dom-StorageEvent-oldValue"><code>oldValue</code></dfn>
attribute represents the old value of the key being changed.</p>
<p>The <dfn
title="dom-StorageEvent-newValue"><code>newValue</code></dfn>
attribute represents the new value of the key being changed.</p>
<p>The <dfn title="dom-StorageEvent-url"><code>url</code></dfn>
attribute represents the address of the document whose key
changed.</p>
<p>The <dfn
title="dom-StorageEvent-storageArea"><code>storageArea</code></dfn>
attribute represents the <code>Storage</code> object that was
affected.</p>
<h5>Threads</h5>
<p>Because of <a href="#localStorageMutex">the use</a> of the
<span>storage mutex</span>, multiple browsing contexts will be able
to access the local storage areas simultaneously in such a manner
that scripts cannot detect any concurrent script execution.</p>
<p>Thus, the <code title="dom-Storage-length">length</code>
attribute of a <code>Storage</code> object, and the value of the
various properties of that object, cannot change while a script is
executing, other than in a way that is predictable by the script
itself.</p>
<!--END storage-->
<!--END complete-->
<h3>Web SQL Database</h3>
<!--START database-->
<!-- Feature requests for future versions (v2):
* deleting databases
* determining how much storage room is left
* handling the database getting corrupted
-->
<h4>Introduction</h4>
<p><i>This section is non-normative.</i></p>
<p>This specification introduces a set of APIs to manipulate
client-side databases using SQL.</p>
<p>The API is asynchronous, so authors are likely to find anonymous
functions (lambdas) very useful in using this API.</p>
<p>Here is an example of a script using this API. First, a function
<code title="">prepareDatabase()</code> is defined. This function
tries to create the database if necessary, giving it one table
called "docids" with two columns ("id" and "name"). If it is
successful, or if the table doesn't need creating, it calls a
section function, <code title="">getDatabase()</code>, which obtains
a handle to the database, and then calls the function to do the
actual work, in this case <code title="">showDocCount()</code>.</p>
<pre>function prepareDatabase(ready, error) {
return openDatabase('documents', '1.0', 'Offline document storage', 5*1024*1024, function (db) {
db.changeVersion('', '1.0', function (t) {
t.executeSql('CREATE TABLE docids (id, name)');
}, error);
});
}
function showDocCount(db, span) {
db.readTransaction(function (t) {
t.executeSql('SELECT COUNT(*) AS c FROM docids', [], function (t, r) {
span.textContent = r.rows[0].c;
}, function (t, e) {
// couldn't read database
span.textContent = '(unknown: ' + e.message + ')';
});
});
}
prepareDatabase(function(db) {
// got database
var span = document.getElementById('doc-count');
showDocCount(db, span);
}, function (e) {
// error getting database
alert(e.message);
});</pre>
<hr>
<p>The <code
title="dom-sqltransaction-executeSql">executeSql()</code> method has
an argument intended to allow variables to be substituted into
statements without risking SQL injection vulnerabilities:</p>
<pre>db.readTransaction(function (t) {
t.executeSql('SELECT title, author FROM docs WHERE id=?', [id], function (t, data) {
report(data.rows[0].title, data.rows[0].author);
});
});</pre>
<hr>
<p>Sometimes, there might be an arbitrary number of variables to
substitute in. Even in these case, the right solution is to
construct the query using only "?" characters, and then to pass the
variables in as the second argument:</p>
<pre>function findDocs(db, resultCallback) {
var q = "";
for each (var i in labels)
q += (q == "" ? "" : ", ") + "?";
db.readTransaction(function (t) {
t.executeSql('SELECT id FROM docs WHERE label IN (' + q + ')', labels, function (t, data) {
resultCallback(data);
});
});
}</pre>
<!--BOILERPLATE middle-w3c-api-intro-->
<!--BOILERPLATE middle-w3c-js-disclaimer-->
<h4 id="sql">The API</h4>
<h5>Databases</h5>
<p>Each <i>origin</i> has an associated set of databases. Each
database has a name and a current version. There is no way to
enumerate or delete the databases available for an origin from this
API.</p>
<p class="note">Each database has one version at a time; a database
can't exist in multiple versions at once. Versions are intended to
allow authors to manage schema changes incrementally and
non-destructively, and without running the risk of old code (e.g. in
another browser window) trying to write to a database with incorrect
assumptions.</p>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <span>WindowDatabase</span> {
<span>Database</span> <span title="dom-opendatabase">openDatabase</span>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize, in optional <span>DatabaseCallback</span> creationCallback);
};
<span>Window</span> implements <span>WindowDatabase</span>;
[Supplemental, NoInterfaceObject]
interface <span>WorkerUtilsDatabase</span> {
<span>Database</span> <span title="dom-opendatabase">openDatabase</span>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize, in optional <span>DatabaseCallback</span> creationCallback);
<span>DatabaseSync</span> <span title="dom-opendatabase-sync">openDatabaseSync</span>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize, in optional <span>DatabaseCallback</span> creationCallback);
};
<span>WorkerUtils</span> implements <span>WorkerUtilsDatabase</span>;
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>DatabaseCallback</dfn> {
void <span title="dom-databasecallback-handleEvent">handleEvent</span>(in <span>Database</span> database);
};</pre>
<p>The <dfn
title="dom-opendatabase"><code>openDatabase()</code></dfn> method on
the <code>Window</code> and <code>WorkerUtils</code> interfaces and
the <dfn
title="dom-opendatabase-sync"><code>openDatabaseSync()</code></dfn>
method on the <code>WorkerUtils</code> interface take the following
arguments: a database name, a database version, a display name, an
estimated size — in bytes — of the data that will be
stored in the database, and optionally a callback to be invoked if
the database has not yet been created. The callback, if provided, is
intended to be used to call <code
title="dom-database-changeVersion">changeVersion()</code>; the
callback is invoked with the database having the empty string as its
version regardless of the given database version. If the callback is
not provided, the database is created with the given database
version as its version.</p>
<p>When invoked, these methods must run the following steps, with all
but the last two steps being run atomically:</p>
<ol>
<li>
<p>The user agent may raise a <code>SECURITY_ERR</code> exception
instead of returning a <code>Database</code> object if the request
violates a policy decision (e.g. if the user agent is configured
to not allow the page to open databases).</p>
</li>
<li>
<p>For the method on the <code>Window</code> object: let <var
title="">origin</var> be the <span>origin</span> of the
<span>active document</span> of the <span>browsing context</span>
of the <code>Window</code> object on which the method was
invoked.</p>
<p>For the methods on the <code>WorkerUtils</code> object: let
<var title="">origin</var> be the <span>origin</span> of the
scripts in the worker.</p>
</li>
<li><p>If the database version provided is not the empty string,
and there is already a database with the given name from the origin
<var title="">origin</var>, but the database has a different
version than the version provided, then throw an
<code>INVALID_STATE_ERR</code> exception and abort these
steps.</p></li>
<li>
<p>If no database with the given name from the origin <var
title="">origin</var> exists, then create the database and let
<var title="">created</var> be true. If a callback was passed to
the method, then set the new database's version to the empty
string. Otherwise, set the new database's version to the given
database version.</p>
<p>Otherwise, if a database with the given name already exists,
let <var title="">created</var> be false.</p>
</li>
<li>
<p>For the <code title="dom-opendatabase">openDatabase()</code>
methods: let <var title="">result</var> be a newly constructed
<code>Database</code> object representing the database with the
given database name from the origin <var
title="">origin</var>.</p>
<p>For the <code
title="dom-opendatabase-sync">openDatabaseSync()</code> method:
let <var title="">result</var> be a newly constructed
<code>DatabaseSync</code> object representing the database with
the given database name from the origin <var
title="">origin</var>.</p>
</li>
<li>
<p>If <var title="">created</var> is false or if no callback was
passed to the method, skip this step. Otherwise:</p>
<p>For the <code title="dom-opendatabase">openDatabase()</code>
methods: <span>queue a task</span> to to invoke the callback with
<var title="">result</var> as its only argument.</p>
<p>For the <code
title="dom-opendatabase-sync">openDatabaseSync()</code> method:
invoke the callback with <var title="">result</var> as its only
argument. If the callback throws an exception, rethrow that
exception and abort these steps.</p>
</li>
<li>
<p>Return <var title="">result</var>.</p>
</li>
</ol>
<p>All strings including the empty string are valid database
names. Database names must be compared in a
<span>case-sensitive</span> manner.</p>
<p class="note">Implementations can support this even in
environments that only support a subset of all strings as database
names by mapping database names (e.g. using a hashing algorithm) to
the supported set of names.</p>
<p>The version that the database was opened with is the <dfn
title="concept-database-expected-version">expected version</dfn> of
this <code>Database</code> or <code>DatabaseSync</code> object. It
can be the empty string, in which case there is no expected version
— any version is fine.</p>
<p>User agents are expected to use the display name and the
estimated database size to optimize the user experience. For
example, a user agent could use the estimated size to suggest an
initial quota to the user. This allows a site that is aware that it
will try to use hundreds of megabytes to declare this upfront,
instead of the user agent prompting the user for permission to
increase the quota every five megabytes.</p>
<h5>Parsing and processing SQL statements</h5>
<p>When the user agent is to <dfn title="preprocess the SQL
statement">preprocess a SQL statement</dfn> <var
title="">sqlStatement</var> with an array of arguments <var
title="">arguments</var>, it must run the following steps:</p>
<ol>
<li><p>Parse <var title="">sqlStatement</var> as a SQL statement,
with the exception that U+003F QUESTION MARK characters (?) can be
used in place of SQL literals in the statement. <a
href="#refsSQL">[SQL]</a></p></li>
<li>
<p>Bind each <code title="">?</code> placeholder with the value of
the argument in the <var title="">arguments</var> array with the
same position. (So the first <code title="">?</code> placeholder
gets bound to the first value in the <var title="">arguments</var>
array, and generally the <var title="">n</var>th <code
title="">?</code> placeholder gets bound to the <var
title="">n</var>th value in the <var title="">arguments</var>
array.)</p>
<p class="note">Binding the <code title="">?</code> placeholders
is done at the literal level, not as string concatenations, so
this provides a way to dynamically insert parameters into a
statement without risk of a SQL injection attack.</p>
<p>The result is <var title="">the statement</var>.</p>
</li>
<li><p>If the <code>Database</code> object that the
<code>SQLTransaction</code> or <code>SQLTransactionSync</code>
object was created from has an <span
title="concept-database-expected-version">expected version</span>
that is neither the empty string nor the actual version of the
database, then mark <var title="">the statement</var> as
bogus. (<span title="dom-sqlerror-code-2">Error code
2</span>.)</p></li>
<li>
<p>Otherwise, if the syntax of <var title="">sqlStatement</var> is
not valid (except for the use of <code title="">?</code>
characters in the place of literals), or the statement uses
features that are not supported (e.g. due to security reasons), or
the number of items in the <var title="">arguments</var> array is
not equal to the number of <code title="">?</code> placeholders in
the statement, or the statement cannot be parsed for some other
reason, then mark <var title="">the statement</var> as
bogus. (<span title="dom-sqlerror-code-5">Error code
5</span>.)</p>
<p>User agents must consider statements that use the <code
title="">BEGIN</code>, <code title="">COMMIT</code>, and <code
title="">ROLLBACK</code> SQL features as being unsupported (and thus
will mark them as bogus), so as to not let these statements
interfere with the explicit transactions managed by the database API
itself.</p>
</li>
<li id="modifications-fail-if-read-only">
<p>Otherwise, if the <i>mode</i> that was used to create the
<code>SQLTransaction</code> or <code>SQLTransactionSync</code>
object is read-only but the statement's main verb can modify the
database, mark the statement as bogus. (<span
title="dom-sqlerror-code-5">Error code 5</span>.)</p>
<p class="note">Only the statement's main verb (e.g. <code
title="">UPDATE</code>, <code title="">SELECT</code>, <code
title="">DROP</code>) is considered here. Thus, a statement like
"<code title="">UPDATE test SET id=0 WHERE 0=1</code>" would be
treated as potentially modifying the database for the purposes
of this step, even though it could never in fact have any
side-effects.</p>
</li>
<li><p>Return <var title="">the statement</var>.</p></li>
</ol>
<p>The user agent must act as if the database was hosted in an
otherwise completely empty environment with no resources. For
example, attempts to read from or write to the file system will
fail.</p>
<p class="note">A future version of this specification will probably
define the exact SQL subset required in more detail.</p>
<h5>Asynchronous database API</h5>
<pre class="idl">interface <dfn>Database</dfn> {
void <span title="dom-database-transaction">transaction</span>(in <span>SQLTransactionCallback</span> callback, in optional <span>SQLTransactionErrorCallback</span> errorCallback, in optional <span>SQLVoidCallback</span> successCallback);
void <span title="dom-database-readTransaction">readTransaction</span>(in <span>SQLTransactionCallback</span> callback, in optional <span>SQLTransactionErrorCallback</span> errorCallback, in optional <span>SQLVoidCallback</span> successCallback);
readonly attribute DOMString <span title="dom-database-version">version</span>;
void <span title="dom-database-changeVersion">changeVersion</span>(in DOMString oldVersion, in DOMString newVersion, in optional <span>SQLTransactionCallback</span> callback, in optional <span>SQLTransactionErrorCallback</span> errorCallback, in optional <span>SQLVoidCallback</span> successCallback);
};
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>SQLVoidCallback</dfn> {
void <span title="dom-sqlvoidcallback-handleEvent">handleEvent</span>();
};
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>SQLTransactionCallback</dfn> {
void <span title="dom-sqltransactioncallback-handleEvent">handleEvent</span>(in <span>SQLTransaction</span> transaction);
};
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>SQLTransactionErrorCallback</dfn> {
void <span title="dom-sqltransactionerrorcallback-handleEvent">handleEvent</span>(in <span>SQLError</span> error);
};</pre>
<p>The <dfn
title="dom-database-transaction"><code>transaction()</code></dfn>
and <dfn
title="dom-database-readTransaction"><code>readTransaction()</code></dfn>
methods takes one to three arguments. When called, these methods must
immediately return and then asynchronously run the <span>transaction
steps</span> with the <i>transaction callback</i> being the first
argument, the <i>error callback</i> being the second argument, if
any, the <i>success callback</i> being the third argument, if any,
and with no <i>preflight operation</i> or <i>postflight
operation</i>.</p>
<p>For the <code
title="dom-database-transaction">transaction()</code> method, the
<i>mode</i> must be read/write. For the <code
title="dom-database-readTransaction">readTransaction()</code>
method, the <i>mode</i> must be read-only.</p>
<p>On getting, the <dfn
title="dom-database-version"><code>version</code></dfn> attribute
must return the current version of the database (as opposed to the
<span title="concept-database-expected-version">expected
version</span> of the <code>Database</code> object).</p>
<p>The <dfn
title="dom-database-changeVersion"><code>changeVersion()</code></dfn>
method allows scripts to atomically verify the version number and
change it at the same time as doing a schema update. When the method
is invoked, it must immediately return, and then asynchronously run
the <span>transaction steps</span> with the <i>transaction
callback</i> being the third argument, the <i>error callback</i>
being the fourth argument, the <i>success callback</i> being the
fifth argument, the <i>preflight operation</i> being the
following:</p>
<ol>
<li><p>Check that the value of the first argument to the <code
title="dom-database-changeVersion">changeVersion()</code> method
exactly matches the database's actual version. If it does not, then
the <i>preflight operation</i> fails.</li>
</ol>
<p>...the <i>postflight operation</i> being the following:</p>
<ol>
<li>Change the database's actual version to the value of the second
argument to the <code
title="dom-database-changeVersion">changeVersion()</code>
method.</li>
<li>Change the <code>Database</code> object's expected version to
the value of the second argument to the <code
title="dom-database-changeVersion">changeVersion()</code>
method.</li>
</ol>
<p>...and the <i>mode</i> being read/write.</p>
<p>If any of the optional arguments are omitted, then they must be
treated as if they were null.</p>
<h6>Executing SQL statements</h6>
<p>The <code title="dom-database-transaction">transaction()</code>,
<code title="dom-database-readTransaction">readTransaction()</code>,
and <code title="dom-database-changeVersion">changeVersion()</code>
methods invoke callbacks with <code>SQLTransaction</code>
objects.</p>
<pre class="idl">typedef sequence<any> <dfn>ObjectArray</dfn>;
interface <dfn>SQLTransaction</dfn> {
void <span title="dom-sqltransaction-executeSql">executeSql</span>(in DOMString sqlStatement, in optional <span>ObjectArray</span> arguments, in optional <span>SQLStatementCallback</span> callback, in optional <span>SQLStatementErrorCallback</span> errorCallback);
};
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>SQLStatementCallback</dfn> {
void <span title="dom-sqlstatementcallback-handleEvent">handleEvent</span>(in <span>SQLTransaction</span> transaction, in <span>SQLResultSet</span> resultSet);
};
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>SQLStatementErrorCallback</dfn> {
boolean <span title="dom-sqlstatementerrorcallback-handleEvent">handleEvent</span>(in <span>SQLTransaction</span> transaction, in <span>SQLError</span> error);
};</pre>
<p>When the <dfn
title="dom-sqltransaction-executeSql"><code>executeSql(<var
title="">sqlStatement</var>, <var title="">arguments</var>, <var
title="">callback</var>, <var
title="">errorCallback</var>)</code></dfn> method is invoked, the
user agent must run the following algorithm. (This algorithm is
relatively simple in that it doesn't actually execute any SQL
— the bulk of the work is actually done as part of the
<span>transaction steps</span>.)</p>
<ol>
<li><p>If the method was not invoked during the execution of a
<code>SQLTransactionCallback</code>,
<code>SQLStatementCallback</code>, or
<code>SQLStatementErrorCallback</code> then raise an
<code>INVALID_STATE_ERR</code> exception. (Calls from inside a
<code>SQLTransactionErrorCallback</code> thus raise an
exception. The <code>SQLTransactionErrorCallback</code> handler is
only called once a transaction has failed, and no SQL statements
can be added to a failed transaction.)</p></li>
<li>
<p><span>Preprocess the SQL statement</span> given as the first
argument to the method (<var title="">sqlStatement</var>), using
the second argument to the method as the <var
title="">arguments</var> array, to obtain <var title="">the
statement</var>.</p>
<p>If the second argument is omitted or null, then treat the <var
title="">arguments</var> array as empty.</p>
</li>
<li><p>Queue up <var title="">the statement</var> in the
transaction, along with the third argument (if any) as the
statement's result set callback and the fourth argument (if any) as
the error callback.</p></li>
</ol>
<h6>Processing model</h6>
<p>The <dfn>transaction steps</dfn> are as follows. These steps must
be run asynchronously. These steps are invoked with a <i>transaction
callback</i>, optionally an <i>error callback</i>, optionally a
<i>success callback</i>, optionally a <i>preflight operation</i>,
optionally a <i>postflight operation</i>, and with a <i>mode</i>
that is either read/write or read-only.</p>
<ol>
<li><p>Open a new SQL transaction to the database, and create a
<code>SQLTransaction</code> object that represents that
transaction. If the <i>mode</i> is read/write, the transaction must
have an exclusive write lock over the entire database. If the
<i>mode</i> is read-only, the transaction must have a shared read
lock over the entire database. The user agent should wait for an
appropriate lock to be available.</p></li>
<li><p>If an error occurred in the opening of the transaction
(e.g. if the user agent failed to obtain an appropriate lock after
an appropriate delay), jump to the last step.</p></li>
<li><p>If a <i>preflight operation</i> was defined for this
instance of the transaction steps, run that. If it fails, then jump
to the last step. (This is basically a hook for the <code
title="dom-database-changeVersion">changeVersion()</code>
method.)</p></li>
<li><p>If the <i>transaction callback</i> is not null, <span>queue
a task</span> to invoke the <i>transaction callback</i> with the
aforementioned <code>SQLTransaction</code> object as its only
argument, and wait for that task to be run.</p></li>
<li><p>If the callback raised an exception, jump to the last
step.</p></li>
<li><p>While there are any statements queued up in the transaction,
perform the following steps for each queued up statement in the
transaction, oldest first. Each statement has a statement,
optionally a result set callback, and optionally an error
callback.</p>
<ol>
<li><p>If the statement is marked as bogus, jump to the "in case
of error" steps below.</p></li>
<li><p>Execute the statement in the context of the transaction.
<a href="#refsSQL">[SQL]</a></p>
<li><p>If the statement failed, jump to the "in case of error"
steps below.</p></li>
<li><p>Create a <code>SQLResultSet</code> object that represents
the result of the statement.</p></li>
<li><p>If the statement has a result set callback that is not
null, <span>queue a task</span> to invoke it with the
<code>SQLTransaction</code> object as its first argument and the
new <code>SQLResultSet</code> object as its second argument, and
wait for that task to be run.</p></li>
<li><p>If the callback was invoked and raised an exception, jump
to the last step in the overall steps.</p></li>
<li><p>Move on to the next statement, if any, or onto the next
overall step otherwise.</p></li>
</ol>
<p>In case of error (or more specifically, if the above substeps
say to jump to the "in case of error" steps), run the following
substeps:</p>
<ol>
<li><p>If the statement had an associated error callback that is
not null, then <span>queue a task</span> to invoke that error
callback with the <code>SQLTransaction</code> object and a newly
constructed <code>SQLError</code> object that represents the
error that caused these substeps to be run as the two arguments,
respectively, and wait for the task to be run.</p></li>
<li><p>If the error callback returns false, then move on to the
next statement, if any, or onto the next overall step
otherwise.</p></li>
<li><p>Otherwise, the error callback did not return false, or
there was no error callback. Jump to the last step in the overall
steps.</p></li>
</ol>
</li>
<li>
<p>If a <i>postflight operation</i> was defined for this instance
of the transaction steps, then: as one atomic operation, commit
the transaction and run the <i>postflight operation</i>. If either
fails, then do neither, and instead jump to the last step. (This
is basically a hook for the <code
title="dom-database-changeVersion">changeVersion()</code>
method.)</p>
<p>Otherwise: commit the transaction and run the <i>postflight
operation</i>. If an error occurred in the committing of the
transaction, jump to the last step.</p>
</li>
<li><p><span>Queue a task</span> to invoke the <i>success
callback</i>, if it is not null.</p></li>
<li><p>End these steps. The next step is only used when something
goes wrong.</p></li>
<li><p><span>Queue a task</span> to invoke the transaction's
<i>error callback</i>, if it is not null, with a newly constructed
<code>SQLError</code> object that represents the last error to have
occurred in this transaction. Rollback the transaction. Any
still-pending statements in the transaction are discarded.</p></li>
</ol>
<p>The <span>task source</span> for these <span
title="concept-task">tasks</span> is the <dfn>database access task
source</dfn>.</p>
<h5>Synchronous database API</h5>
<pre class="idl">interface <dfn>DatabaseSync</dfn> {
void <span title="dom-database-sync-transaction">transaction</span>(in <span>SQLTransactionSyncCallback</span> callback);
void <span title="dom-database-sync-readTransaction">readTransaction</span>(in <span>SQLTransactionSyncCallback</span> callback);
readonly attribute DOMString <span title="dom-database-sync-version">version</span>;
void <span title="dom-database-sync-changeVersion">changeVersion</span>(in DOMString oldVersion, in DOMString newVersion, in optional <span>SQLTransactionSyncCallback</span> callback);
};
[Callback=FunctionOnly, NoInterfaceObject]
interface <dfn>SQLTransactionSyncCallback</dfn> {
void <span title="dom-sqltransactionsynccallback-handleEvent">handleEvent</span>(in <span>SQLTransactionSync</span> transaction);
};</pre>
<p>The <dfn
title="dom-database-sync-transaction"><code>transaction()</code></dfn>
and <dfn
title="dom-database-sync-readTransaction"><code>readTransaction()</code></dfn>
methods must run the following steps:</p>
<ol>
<li><p>If the method was the <code
title="dom-database-sync-transaction">transaction()</code> method,
<span>create a <code>SQLTransactionSync</code> object</span> for a
read/write transaction. Otherwise, <span>create a
<code>SQLTransactionSync</code> object</span> for a read-only
transaction. In either case, if this throws an exception, then
rethrow it and abort these steps. Otherwise, let <var
title="">transaction</var> be the newly created
<code>SQLTransactionSync</code> object.</p></li>
<li><p>If the first argument is null, rollback the transaction,
throw a <code>SQLException</code> exception, and abort these
steps. (<span title="dom-sqlerror-code-0">Error code
0</span>.)</p></li>
<li><p>Invoke the callback given by the first argument, passing it
the <var title="">transaction</var> object as its only
argument.</p></li>
<li><p>Mark the <code>SQLTransactionSync</code> object as <i
title="">stale</i>.</p>
<li><p>If the callback was terminated by an exception, then
rollback the transaction, rethrow that exception, and abort these
steps.</p></li>
<li><p>Commit the transaction.</p></li>
<li><p>If an error occurred in the committing of the transaction,
rollback the transaction, throw a <code>SQLException</code>
exception, and abort these steps.</p></li>
</ol>
<p>On getting, the <dfn
title="dom-database-sync-version"><code>version</code></dfn>
attribute must return the current version of the database (as
opposed to the <span
title="concept-database-expected-version">expected version</span> of
the <code>DatabaseSync</code> object).</p>
<p>The <dfn
title="dom-database-sync-changeVersion"><code>changeVersion()</code></dfn>
method allows scripts to atomically verify the version number and
change it at the same time as doing a schema update. When the method
is invoked, it must run the following steps:</p>
<ol>
<li><p><span>Create a <code>SQLTransactionSync</code> object</span>
for a read/write transaction. If this throws an exception, then
rethrow it and abort these steps. Otherwise, let <var
title="">transaction</var> be the newly created
<code>SQLTransactionSync</code> object.</p></li>
<li><p>Check that the value of the first argument to the <code
title="dom-database-sync-changeVersion">changeVersion()</code>
method exactly matches the database's actual version. If it does
not, then throw a <code>SQLException</code> exception and abort
these steps. (<span title="dom-sqlerror-code-2">Error code
2</span>.)</p></li>
<li><p>If the third argument is not null, invoke the callback given
by the third argument, passing it the <var
title="">transaction</var> object as its only argument.</p></li>
<li><p>Mark the <code>SQLTransactionSync</code> object as <i
title="">stale</i>.</p>
<li><p>If the callback was terminated by an exception, then
rollback the transaction, rethrow the exception, and abort these
steps.</p></li>
<li><p>Commit the transaction.</p></li>
<li><p>If an error occurred in the committing of the transaction,
rollback the transaction, throw a <code>SQLException</code>
exception, and abort these steps.</p></li>
<li>Change the database's actual version to the value of the second
argument to the <code
title="dom-database-sync-changeVersion">changeVersion()</code>
method.</li>
<li>Change the <code>Database</code> object's expected version to
the value of the second argument to the <code
title="dom-database-sync-changeVersion">changeVersion()</code>
method.</li>
</ol>
<hr>
<p>When the user agent is to <dfn>create a
<code>SQLTransactionSync</code> object</dfn> for a transaction that
is either read/write or read-only, it must run the following
steps:</p>
<ol>
<li><p>Open a new SQL transaction to the database, and create a
<code>SQLTransactionSync</code> object that represents that
transaction. If the <i>mode</i> is read/write, the transaction must
have an exclusive write lock over the entire database. If the
<i>mode</i> is read-only, the transaction must have a shared read
lock over the entire database. The user agent should wait for an
appropriate lock to be available.</p></li>
<li><p>If an error occurred in the opening of the transaction
(e.g. if the user agent failed to obtain an appropriate lock after
an appropriate delay), throw a <code>SQLException</code> exception
and abort these steps.</p></li>
<li><p>Return the newly created <code>SQLTransactionSync</code>
object.</p></li>
</ol>
<h6>Executing SQL statements</h6>
<p>The <code
title="dom-database-sync-transaction">transaction()</code>, <code
title="dom-database-sync-readTransaction">readTransaction()</code>,
and <code
title="dom-database-sync-changeVersion">changeVersion()</code>
methods invoke callbacks that are passed
<code>SQLTransactionSync</code> objects.</p>
<pre class="idl">// typedef sequence<any> <span>ObjectArray</span>;
interface <dfn>SQLTransactionSync</dfn> {
<span>SQLResultSet</span> <span title="dom-sqltransaction-sync-executeSql">executeSql</span>(in DOMString sqlStatement, in optional <span>ObjectArray</span> arguments);
};</pre>
<p>A <code>SQLTransactionSync</code> object is initially <i
title="">fresh</i>, but it will be marked as <i title="">stale</i>
once it has been committed or rolled back.</p>
<p>When the <dfn
title="dom-sqltransaction-sync-executeSql"><code>executeSql(<var
title="">sqlStatement</var>, <var
title="">arguments</var>)</code></dfn> method is invoked, the user
agent must run the following algorithm:</p>
<ol>
<li><p>If the <code>SQLTransactionSync</code> object is <i
title="">stale</i>, then throw an <code>INVALID_STATE_ERR</code>
exception.</p></li>
<li>
<p><span>Preprocess the SQL statement</span> given as the first
argument to the method (<var title="">sqlStatement</var>), using
the second argument to the method as the <var
title="">arguments</var> array, to obtain <var title="">the
statement</var>.</p>
<p>If the second argument is omitted or null, then treat the <var
title="">arguments</var> array as empty.</p>
</li>
<li><p>If the statement is marked as bogus, throw a
<code>SQLException</code> exception.</p></li>
<li><p>Execute the statement in the context of the transaction.
<a href="#refsSQL">[SQL]</a></p>
<li><p>If the statement failed, throw a <code>SQLException</code>
exception.</p></li>
<li><p>Create a <code>SQLResultSet</code> object that represents
the result of the statement.</p></li>
<li><p>Return the newly created <code>SQLResultSet</code>
object.</p></li>
</ol>
<h5>Database query results</h5>
<p>The <code title="dom-sqltransaction-executeSql">executeSql()</code>
method invokes its callback with a <code>SQLResultSet</code> object
as an argument.</p>
<pre class="idl">interface <dfn>SQLResultSet</dfn> {
readonly attribute long <span title="dom-SQLResultSet-insertId">insertId</span>;
readonly attribute long <span title="dom-SQLResultSet-rowsAffected">rowsAffected</span>;
readonly attribute <span>SQLResultSetRowList</span> <span title="dom-SQLResultSet-rows">rows</span>;
};</pre>
<p>The <dfn
title="dom-SQLResultSet-insertId"><code>insertId</code></dfn>
attribute must return the row ID of the row that the
<code>SQLResultSet</code> object's SQL statement inserted into the
database, if the statement inserted a row. If the statement inserted
multiple rows, the ID of the last row must be the one returned. If
the statement did not insert a row, then the attribute must instead
raise an <code>INVALID_ACCESS_ERR</code> exception.</p>
<p>The <dfn
title="dom-SQLResultSet-rowsAffected"><code>rowsAffected</code></dfn>
attribute must return the number of rows that were changed by the
SQL statement. If the statement did not affected any rows, then the
attribute must return zero. For "SELECT" statements, this returns
zero (querying the database doesn't affect any rows).</p>
<p>The <dfn title="dom-SQLResultSet-rows"><code>rows</code></dfn>
attribute must return a <code>SQLResultSetRowList</code>
representing the rows returned, in the order returned by the
database. If no rows were returned, then the object will be empty
(its <code title="dom-SQLResultSetRowList-length">length</code> will
be zero).</p>
<pre class="idl">interface <dfn>SQLResultSetRowList</dfn> {
readonly attribute unsigned long <span title="dom-SQLResultSetRowList-length">length</span>;
getter <span>any</span> <span title="dom-SQLResultSetRowList-item">item</span>(in unsigned long index);
};</pre>
<p class="note">For the asynchronous API, implementors are
encouraged to prefetch all the data for
<code>SQLResultSetRowList</code> objects when the object is
constructed (before the result set callback is invoked), rather than
on-demand, for better responsiveness. For the synchronous API, an
on-demand lazy evaluation implementation strategy is encouraged
instead, for better performance.</p>
<p><code>SQLResultSetRowList</code> objects have a <dfn
title="dom-SQLResultSetRowList-length"><code>length</code></dfn>
attribute that must return the number of rows it represents (the
number of rows returned by the database). This is the <var
title="dom-SQLResultSetRowList-length">length</var>.</p>
<p class="note">Fetching the <code
title="dom-SQLResultSetRowList-length">length</code> might be
expensive, and authors are thus encouraged to avoid using it (or
enumerating over the object, which implicitly uses it) where
possible.</p>
<p>The object's <span>indices of the supported indexed
properties</span> are the numbers in the range zero to <span title=""><var
title="dom-SQLResultSetRowList-length">length</var>-1</span>, unless
the <var title="dom-SQLResultSetRowList-length">length</var> is
zero, in which case there are no <span>supported indexed
properties</span>.</p>
<p>The <dfn title="dom-SQLResultSetRowList-item"><code>item(<var
title="">index</var>)</code></dfn> attribute must return the row
with the given index <var title="">index</var>. If there is no such
row, then the method must return null.</p>
<p>Each row must be represented by a native ordered dictionary data
type. In the JavaScript binding, this must be <code>Object</code>.
Each row object must have one property (or dictionary entry) per
column, with those properties enumerating in the order that these
columns were returned by the database. Each property must have the
name of the column and the value of the cell, as they were returned
by the database.</p>
<h5>Errors and exceptions</h5>
<p>Errors in the asynchronous database API are reported using
callbacks that have a <code>SQLError</code> object as one of their
arguments.</p>
<pre class="idl">interface <dfn>SQLError</dfn> {
const unsigned short <span title="dom-SQLException-code-UNKNOWN">UNKNOWN_ERR</span> = 0;
const unsigned short <span title="dom-SQLException-code-DATABASE">DATABASE_ERR</span> = 1;
const unsigned short <span title="dom-SQLException-code-VERSION">VERSION_ERR</span> = 2;
const unsigned short <span title="dom-SQLException-code-TOO_LARGE">TOO_LARGE_ERR</span> = 3;
const unsigned short <span title="dom-SQLException-code-QUOTA">QUOTA_ERR</span> = 4;
const unsigned short <span title="dom-SQLException-code-SYNTAX">SYNTAX_ERR</span> = 5;
const unsigned short <span title="dom-SQLException-code-CONSTRAINT">CONSTRAINT_ERR</span> = 6;
const unsigned short <span title="dom-SQLException-code-TIMEOUT">TIMEOUT_ERR</span> = 7;
readonly attribute unsigned short <span title="dom-SQLError-code">code</span>;
readonly attribute DOMString <span title="dom-SQLError-message">message</span>;
};</pre>
<p>The <dfn title="dom-SQLError-code"><code>code</code></dfn> IDL
attribute must return the most appropriate code from the table
below.</p>
<p>The <dfn title="dom-SQLError-message"><code>message</code></dfn>
IDL attribute must return an error message describing the error
encountered. The message should be localized to the user's
language.</p>
<hr>
<p>Errors in the synchronous database API are reported using
<code>SQLException</code> exceptions:</p>
<pre class="idl">exception <dfn>SQLException</dfn> {
const unsigned short <span title="dom-SQLException-code-UNKNOWN">UNKNOWN_ERR</span> = 0;
const unsigned short <span title="dom-SQLException-code-DATABASE">DATABASE_ERR</span> = 1;
const unsigned short <span title="dom-SQLException-code-VERSION">VERSION_ERR</span> = 2;
const unsigned short <span title="dom-SQLException-code-TOO_LARGE">TOO_LARGE_ERR</span> = 3;
const unsigned short <span title="dom-SQLException-code-QUOTA">QUOTA_ERR</span> = 4;
const unsigned short <span title="dom-SQLException-code-SYNTAX">SYNTAX_ERR</span> = 5;
const unsigned short <span title="dom-SQLException-code-CONSTRAINT">CONSTRAINT_ERR</span> = 6;
const unsigned short <span title="dom-SQLException-code-TIMEOUT">TIMEOUT_ERR</span> = 7;
unsigned short <span title="dom-SQLException-code">code</span>;
DOMString <span title="dom-SQLException-message">message</span>;
};</pre>
<p>The <dfn title="dom-SQLException-code"><code>code</code></dfn>
IDL attribute must return the most appropriate code from the table
below.</p>
<p>The <dfn
title="dom-SQLException-message"><code>message</code></dfn> IDL
attribute must return an error message describing the error
encountered. The message should be localized to the user's
language.</p>
<hr>
<p>The error codes are as follows:</p>
<table>
<thead>
<tr>
<th>Constant
<th>Code
<th>Situation
<tbody>
<tr>
<td><dfn title="dom-SQLException-code-UNKNOWN"><code>UNKNOWN_ERR</code></dfn>
<td><dfn title="dom-sqlerror-code-0">0</dfn>
<td>The transaction failed for reasons unrelated to the database
itself and not covered by any other error code.
<tr>
<td><dfn title="dom-SQLException-code-DATABASE"><code>DATABASE_ERR</code></dfn>
<td><dfn title="dom-sqlerror-code-1">1</dfn>
<td>The statement failed for database reasons not covered by any
other error code.
<tr>
<td><dfn title="dom-SQLException-code-VERSION"><code>VERSION_ERR</code></dfn>
<td><dfn title="dom-sqlerror-code-2">2</dfn>
<td>The operation failed because the actual database version was
not what it should be. For example, a statement found that the
actual database version no longer matched the <span
title="concept-database-expected-version">expected version</span>
of the <code>Database</code> or <code>DatabaseSync</code> object,
or the <code
title="dom-database-changeversion">Database.changeVersion()</code>
or <code
title="dom-database-sync-changeversion">DatabaseSync.changeVersion()</code>
methods were passed a version that doesn't match the actual
database version.
<tr>
<td><dfn title="dom-SQLException-code-TOO_LARGE"><code>TOO_LARGE_ERR</code></dfn>
<td><dfn title="dom-sqlerror-code-3">3</dfn>
<td>The statement failed because the data returned from the
database was too large. The SQL "LIMIT" modifier might be useful
to reduce the size of the result set.
<tr>
<td><dfn title="dom-SQLException-code-QUOTA"><code>QUOTA_ERR</code></dfn>
<td><dfn title="dom-sqlerror-code-4">4</dfn>
<td>The statement failed because there was not enough remaining
storage space, or the storage quota was reached and the user
declined to give more space to the database.
<tr>
<td><dfn title="dom-SQLException-code-SYNTAX"><code>SYNTAX_ERR</code></dfn>
<td><dfn title="dom-sqlerror-code-5">5</dfn>
<td>The statement failed because of a syntax error, or the number
of arguments did not match the number of <code title="">?</code>
placeholders in the statement, or the statement tried to use a
statement that is not allowed, such as <code
title="">BEGIN</code>, <code title="">COMMIT</code>, or <code
title="">ROLLBACK</code>, or the statement tried to use a verb
that could modify the database but the transaction was read-only.
<tr>
<td><dfn title="dom-SQLException-code-CONSTRAINT"><code>CONSTRAINT_ERR</code></dfn>
<td><dfn title="dom-sqlerror-code-6">6</dfn>
<td>An <code title="">INSERT</code>, <code
title="">UPDATE</code>, or <code title="">REPLACE</code>
statement failed due to a constraint failure. For example,
because a row was being inserted and the value given for the
primary key column duplicated the value of an existing row.
<tr>
<td><dfn title="dom-SQLException-code-TIMEOUT"><code>TIMEOUT_ERR</code></dfn>
<td><dfn title="dom-sqlerror-code-7">7</dfn>
<td>A lock for the transaction could not be obtained in a
reasonable time.
</table>
<h4>Web SQL</h4>
<p>User agents must implement the SQL dialect supported by Sqlite 3.6.19.</p>
<p>When converting bound arguments to SQL data types, the JavaScript
ToPrimitive operator must be applied to obtain the raw value to be
processed. <a href="#refsECMA262">[ECMA262]</a>.</p>
<!--END database-->
<!--END complete--> <!-- the next <h3> section needs reworking if we re-add database to complete -->
<h3>Common concerns</h3>
<!--START complete-->
<!--START database-->
<!--START storage-->
<h4>Disk space</h4>
<p>User agents should limit the total amount of space allowed for
<!--END database-->
storage areas.
<!--END storage-->
<!--END complete-->
<!--START database-->
databases.
<!--END database-->
these storage features.
<!--START complete-->
<!--START database-->
<!--START storage-->
</p>
<p>User agents should guard against sites storing data under the
origins other affiliated sites, e.g. storing up to the limit in
a1.example.com, a2.example.com, a3.example.com, etc, circumventing
the main example.com storage limit.</p>
<p>User agents may prompt the user when quotas are reached, allowing
the user to grant a site more space. This enables sites to store
many user-created documents on the user's computer, for
instance.</p>
<p>User agents should allow users to see how much space each domain
is using.</p>
<!--END database-->
<!--<p>If the storage area space limit is reached during a <code
title="dom-Storage-setItem">setItem()</code> call, the method will
raise an exception.</p>-->
<!--START database-->
<p>A mostly arbitrary limit of five megabytes per
<span>origin</span> is recommended. Implementation feedback is
welcome and will be used to update this suggestion in the
future.</p>
<h4>Privacy</h4>
<h5>User tracking</h5>
<p>A third-party advertiser (or any entity capable of getting
content distributed to multiple sites) could use a unique identifier
stored in its
<!--END database-->
local storage area
<!--END storage-->
<!--END complete-->
or its
<!--START database-->
client-side databases
<!--START complete-->
<!--START storage-->
to track a user across multiple sessions, building a profile of the
user's interests to allow for highly targeted advertising. In
conjunction with a site that is aware of the user's real identity
(for example an e-commerce site that requires authenticated
credentials), this could allow oppressive groups to target
individuals with greater accuracy than in a world with purely
anonymous Web usage.</p>
<p>There are a number of techniques that can be used to mitigate the
risk of user tracking:</p>
<dl>
<dt>Blocking third-party storage</dt>
<dd>
<p>User agents may restrict access to
<!--END database-->
the <code title="dom-localStorage">localStorage</code> objects
<!--END storage-->
<!--END complete-->
and
<!--START database-->
the database objects
<!--START complete-->
<!--START storage-->
to scripts originating at the domain of the top-level document of
the <span>browsing context</span>, for instance denying access to
the API for pages from other domains running in
<code>iframe</code>s.</p>
</dd>
<dt>Expiring stored data</dt>
<dd>
<p>User agents may, if so configured by the user, automatically
delete stored data after a period of time.</p>
<!--END database-->
<p>For example, a user agent could be configured to treat
third-party local storage areas as session-only storage, deleting
the data once the user had closed all the <span title="browsing
context">browsing contexts</span> that could access it.</p>
<!--START database-->
<p>This can restrict the ability of a site to track a user, as the
site would then only be able to track the user across multiple
sessions when he authenticates with the site itself (e.g. by
making a purchase or logging in to a service).</p>
<p>However, this also reduces the usefulness of the API as a
long-term storage mechanism. It can also put the user's data at
risk, if the user does not fully understand the implications of
data expiration.</p>
<!--END database-->
<!--v2 consider adding an explicit way for sites to state when
data should expire, as in localStorage.expireData(365); -->
<!--START database-->
</dd>
<dt>Treating persistent storage as cookies</dt>
<dd>
<p>If users attempt to protect their privacy by clearing cookies
without also clearing data stored in the
<!--END database-->
local storage area,
<!--END storage-->
<!--END complete-->
<!--START database-->
relevant databases,
<!--END database-->
local storage area and relevant databases,
<!--START complete-->
<!--START database-->
<!--START storage-->
sites can defeat those attempts by using the two features as
redundant backup for each other. User agents should present the
interfaces for clearing these in a way that helps users to
understand this possibility and enables them to delete data in all
persistent storage features simultaneously. <a
href="#refsCOOKIES">[COOKIES]</a></p>
</dd>
<dt>Site-specific white-listing of access to
<!--END database-->
local storage areas
<!--END storage-->
<!--END complete-->
and
<!--START database-->
databases
<!--START complete-->
<!--START storage-->
</dt>
<dd>
<!--END database-->
<p>User agents may allow sites to access session storage areas in
an unrestricted manner, but require the user to authorize access
to local storage areas.</p>
<!--END storage-->
<!--END complete-->
<!--START database-->
<p>User agents may require the user to authorize access to
databases before a site can use the feature.</p>
<!--START complete-->
<!--START storage-->
</dd>
<dt>Origin-tracking of stored data</dt>
<dd>
<p>User agents may record the <span title="origin">origins</span>
of sites that contained content from third-party origins that
caused data to be stored.</p>
<p>If this information is then used to present the view of data
currently in persistent storage, it would allow the user to make
informed decisions about which parts of the persistent storage to
prune. Combined with a blacklist ("delete this data and prevent
this domain from ever storing data again"), the user can restrict
the use of persistent storage to sites that he trusts.</p>
</dd>
<dt>Shared blacklists</dt>
<dd>
<p>User agents may allow users to share their persistent storage
domain blacklists.</p>
<p>This would allow communities to act together to protect their
privacy.</p>
</dd>
</dl>
<p>While these suggestions prevent trivial use of this API for user
tracking, they do not block it altogether. Within a single domain, a
site can continue to track the user during a session, and can then
pass all this information to the third party along with any
identifying information (names, credit card numbers, addresses)
obtained by the site. If a third party cooperates with multiple
sites to obtain such information, a profile can still be
created.</p>
<p>However, user tracking is to some extent possible even with no
cooperation from the user agent whatsoever, for instance by using
session identifiers in URLs, a technique already commonly used for
innocuous purposes but easily repurposed for user tracking (even
retroactively). This information can then be shared with other
sites, using using visitors' IP addresses and other user-specific
data (e.g. user-agent headers and configuration settings) to combine
separate sessions into coherent user profiles.</p>
<h5>Sensitivity of data</h5>
<p>User agents should treat persistently stored data as potentially
sensitive; it's quite possible for e-mails, calendar appointments,
health records, or other confidential documents to be stored in this
mechanism.</p>
<p>To this end, user agents should ensure that when deleting data,
it is promptly deleted from the underlying storage.</p>
<h4>Security</h4>
<h5>DNS spoofing attacks</h5>
<p>Because of the potential for DNS spoofing attacks, one cannot
guarantee that a host claiming to be in a certain domain really is
from that domain. To mitigate this, pages can use SSL. Pages using
SSL can be sure that only pages using SSL that have certificates
identifying them as being from the same domain can access their
<!--END database-->
storage areas.
<!--END storage-->
<!--END complete-->
<!--START database-->
databases.
<!--END database-->
storage areas and databases.
<!--START complete-->
<!--START database-->
<!--START storage-->
</p>
<h5>Cross-directory attacks</h5>
<p>Different authors sharing one host name, for example users
hosting content on <code>geocities.com</code>, all share one
<!--END database-->
local storage object.
<!--END storage-->
<!--END complete-->
<!--START database-->
set of databases.
<!--END database-->
common set of storage objects and databases.
<!--START complete-->
<!--START database-->
<!--START storage-->
There is no feature to restrict the access by pathname. Authors on
shared hosts are therefore recommended to avoid using these
features, as it would be trivial for other authors to read the data
and overwrite it.</p>
<p class="note">Even if a path-restriction feature was made
available, the usual DOM scripting security model would make it
trivial to bypass this protection and access the data from any
path.</p>
<h5>Implementation risks</h5>
<p>The two primary risks when implementing these persistent storage
features are letting hostile sites read information from other
domains, and letting hostile sites write information that is then
read from other domains.</p>
<p>Letting third-party sites read data that is not supposed to be
read from their domain causes <em>information leakage</em>, For
example, a user's shopping wishlist on one domain could be used by
another domain for targeted advertising; or a user's
work-in-progress confidential documents stored by a word-processing
site could be examined by the site of a competing company.</p>
<p>Letting third-party sites write data to the persistent storage of
other domains can result in <em>information spoofing</em>, which is
equally dangerous. For example, a hostile site could add items to a
user's wishlist; or a hostile site could set a user's session
identifier to a known ID that the hostile site can then use to track
the user's actions on the victim site.</p>
<p>Thus, strictly following the <span>origin</span> model described
in this specification is important for user security.</p>
<!--END storage-->
<!--END complete-->
<h5>SQL and user agents</h5>
<p>User agent implementors are strongly encouraged to audit all
their supported SQL statements for security implications. For
example, <code title="">LOAD DATA INFILE</code> is likely to pose
security risks and there is little reason to support it.</p>
<p>In general, it is recommended that user agents not support
features that control how databases are stored on disk. For example,
there is little reason to allow Web authors to control the character
encoding used in the disk representation of the data, as all data in
JavaScript is implicitly UTF-16.</p>
<h5>SQL injection</h5>
<p>Authors are strongly recommended to make use of the <code
title="">?</code> placeholder feature of the <code
title="dom-sqltransaction-executeSql">executeSql()</code> method,
and to never construct SQL statements on the fly.</p>
<!--END database-->
<!--START complete-->
<!--FIXUP +1-->
<!--START html--><!--START html5-->
<h2 id="editing"><dfn>User Interaction</dfn></h2>
<p>This section describes various features that allow authors to
enable users to edit documents and parts of documents
interactively.</p>
<h3>The <dfn title="attr-hidden"><code>hidden</code></dfn> attribute</h3>
<p>All <span>HTML elements</span> may have the <code
title="attr-hidden">hidden</code> content attribute set. The <code
title="attr-hidden">hidden</code> attribute is a <span>boolean
attribute</span>. When specified on an element, it indicates that
the element is not yet, or is no longer, relevant. <span
class="impl">User agents should not render elements that have the
<code title="attr-hidden">hidden</code> attribute
specified.</span></p>
<div class="example">
<p>In the following skeletal example, the attribute is used to hide
the Web game's main screen until the user logs in:</p>
<pre> <h1>The Example Game</h1>
<section id="login">
<h2>Login</h2>
<form>
...
<!-- calls login() once the user's credentials have been checked -->
</form>
<script>
function login() {
// switch screens
document.getElementById('login').hidden = true;
document.getElementById('game').hidden = false;
}
</script>
</section>
<section id="game" hidden>
...
</section></pre>
</div>
<p>The <code title="attr-hidden">hidden</code> attribute must not be
used to hide content that could legitimately be shown in another
presentation. For example, it is incorrect to use <code
title="attr-hidden">hidden</code> to hide panels in a tabbed dialog,
because the tabbed interface is merely a kind of overflow
presentation — showing all the form controls in one big page
with a scrollbar would be equivalent, and no less correct.</p>
<p>Elements in a section hidden by the <code
title="attr-hidden">hidden</code> attribute are still active,
e.g. scripts and form controls in such sections still render execute
and submit respectively. Only their presentation to the user
changes.</p>
<div class="impl">
<p>The <dfn title="dom-hidden"><code>hidden</code></dfn> IDL
attribute must <span>reflect</span> the content attribute of the
same name.</p>
</div>
<h3>Activation</h3>
<!-- v2 idea: HTMLImageElement.click(x, y); or clickPoint(), if
click() can't be done in IE; can this be emulated in IE by
posting a synthetic mouse click event with those X and Y
coords? (ack Csaba Gabor)
-->
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-click">click</code>()</dt>
<dd>
<p>Acts as if the element was clicked.</p>
</dd>
</dl>
<div class="impl">
<p>Each element has a <var title="">click in progress</var> flag,
initially set to false.</p>
<p>The <dfn title="dom-click"><code>click()</code></dfn> method must
run these steps:</p>
<ol>
<li><p>If the element's <var title="">click in progress</var> flag
is set to true, then abort these steps.</p></li>
<li><p>Set the <var title="">click in progress</var> flag on the
element to true.</p></li>
<li><p>If the element has a defined <span>activation behavior</span>,
<span>run synthetic click activation steps</span> on the
element. Otherwise, <span>fire a <code>click</code> event</span> at
the element.</p></li>
<li><p>Set the <var title="">click in progress</var> flag on the
element to false.</p></li>
</ol>
</div>
<h3>Scrolling elements into view</h3> <!-- maybe this should move to [CSSOM] -->
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-scrollIntoView">scrollIntoView</code>( [ <var title="">top</var> ] )</dt>
<dd>
<p>Scrolls the element into view. If the <var title="">top</var>
argument is true, then the element will be scrolled to the top of
the viewport, otherwise it'll be scrolled to the bottom. The
default is the top.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-scrollIntoView"><code>scrollIntoView([<var
title="">top</var>])</code></dfn> method, when called, must cause
the element on which the method was called to have the attention of
the user called to it.</p>
<p class="note">In a speech browser, this could happen by having the
current playback position move to the start of the given
element.</p>
<p>In visual user agents, if the argument is present and has the
value false, the user agent should scroll the element into view such
that both the bottom and the top of the element are in the viewport,
with the bottom of the element aligned with the bottom of the
viewport. If it isn't possible to show the entire element in that
way, or if the argument is omitted or is true, then the user agent
should instead align the top of the element with the top of the
viewport. If the entire scrollable part of the content is visible
all at once (e.g. if a page is shorter than the viewport), then the
user agent should not scroll anything. Visual user agents should
further scroll horizontally as necessary to bring the element to the
attention of the user.</p>
<p>Non-visual user agents may ignore the argument, or may treat it
in some media-specific manner most useful to the user.</p>
</div>
<h3>Focus</h3>
<!-- http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%20%0A...%3Cform%3E%3Cinput%20name%3Da%20onfocus%3D%22value%2B%3D1%3Bd.name%3D%27a%27%3Bname%3D%27d%27%3Bb.focus()%22%3E%0A%3Cinput%20name%3Db%20onfocus%3D%22value%2B%3D1%3Bc.focus()%22%3E%0A%3Cinput%20name%3Dc%20onfocus%3D%22value%2B%3D1%3Bd.focus()%22%3E%0A%3Cinput%20name%3Dd%20onfocus%3D%22value%2B%3D1%3Ba.focus()%22%3E -->
<!-- http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A...%3Cform%3E%0A%3Ctextarea%20name%3Dt%20cols%3D100%20rows%3D3%3E%3C%2Ftextarea%3E%3Cp%3E%0A%3Cinput%20name%3Da%20onfocus%3D%22t.value%2B%3D%27af1%20%27%3Bb.focus()%3Balert(document.activeElement.name)%3Bt.value%2B%3D%27af2%20%27%3B%22%20onblur%3D%22t.value%2B%3D%27ab%20%27%3B%22%3E%0A%3Cinput%20name%3Db%20onfocus%3D%22t.value%2B%3D%27bf1%20%27%3Bc.focus()%3Bt.value%2B%3D%27bf2%20%27%3B%22%20onblur%3D%22t.value%2B%3D%27bb%20%27%3B%22%3E%0A%3Cinput%20name%3Dc%20onfocus%3D%22t.value%2B%3D%27cf1%20%27%3Bc.focus()%3Bt.value%2B%3D%27cf2%20%27%3B%22%20onblur%3D%22t.value%2B%3D%27cb%20%27%3B%22%3E%0A -->
<!-- http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%3Cbody%20onload%3D%22document.forms%5B0%5D.a.focus()%22%3E%0A...%3Cform%3E%0A%3Ctextarea%20name%3Dt%20cols%3D100%20rows%3D3%3E%3C%2Ftextarea%3E%3Cp%3E%0A%3Cinput%20name%3Da%20onblur%3D%22t.value%2B%3D'ab%20'%3B%20b.focus()%3B%22%3E%0A%3Cinput%20name%3Db%20onfocus%3D%22t.value%2B%3D'bf1%20'%3Ba.focus()%3Bt.value%2B%3D'bf2%20'%3B%22%20onblur%3D%22t.value%2B%3D'bb%20'%3B%22%3E -->
<!-- http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%3Cbody%3E...%3Cform%3E%0A%3Ctextarea%20name%3Dt%20cols%3D100%20rows%3D3%3E%3C%2Ftextarea%3E%3Cp%3E%0A%3Cinput%20name%3Da%20onfocus%3D%22t.value%2B%3D%27af%20%27%3B%22%20onblur%3D%22t.value%2B%3D%27ab1%20%27%3Bb.focus()%3Bt.value%2B%3D%27ab2%20%27%3B%22%3E%0A%3Cinput%20name%3Db%20onfocus%3D%22t.value%2B%3D%27bf1%20%27%3Ba.focus()%3Bt.value%2B%3D%27bf2%20%27%3B%22%20onblur%3D%22t.value%2B%3D%27bb%20%27%3B%22%3E -->
<!-- v2: more things to define, if no other specs define them:
- define onfocus/onblur behaviour for Window
- Other things to look at are IE's focus APIs (HTMLElement.setActive(),
onBeforeActivate, onActivate, onBeforeDeactivate, onDeactivate):
https://bugzilla.mozilla.org/show_bug.cgi?id=296471
https://bugzilla.mozilla.org/show_bug.cgi?id=296469
http://msdn.microsoft.com/workshop/author/dhtml/reference/methods/setactive.asp
http://msdn.microsoft.com/workshop/author/dhtml/reference/events/onbeforeactivate.asp
-->
<div class="impl">
<p>When an element is <i>focused</i>, key events received by the
document must be targeted at that element. There may be no element
focused; when no element is focused, key events received by the
document must be targeted at <span>the body element</span>.</p>
<p>User agents may track focus for each <span>browsing
context</span> or <code>Document</code> individually, or may support
only one focused element per <span>top-level browsing context</span>
— user agents should follow platform conventions in this
regard.</p>
<p>Which elements within a <span>top-level browsing context</span>
currently have focus must be independent of whether or not the
<span>top-level browsing context</span> itself has the <i>system
focus</i>.</p>
<p class="note">When an element is focused, the element matches the
CSS <code>:focus</code> pseudo-class.</p>
</div>
<h4>Sequential focus navigation</h4>
<p>The <dfn title="attr-tabindex"><code>tabindex</code></dfn>
content attribute specifies whether the element is focusable,
whether it can be reached using sequential focus navigation, and the
relative order of the element for the purposes of sequential focus
navigation. The name "tab index" comes from the common use of the
"tab" key to navigate through the focusable elements. The term
"tabbing" refers to moving forward through the focusable elements
that can be reached using sequential focus navigation.</p>
<p>The <code title="attr-tabindex">tabindex</code> attribute, if
specified, must have a value that is a <span>valid
integer</span>.</p>
<div class="impl">
<p>If the attribute is specified, it must be parsed using the
<span>rules for parsing integers</span>. The attribute's values have
the following meanings:</p>
<dl>
<dt>If the attribute is omitted or parsing the value returns an
error</dt>
<dd>
<p>The user agent should follow platform conventions to determine if
the element is to be focusable and, if so, whether the element can
be reached using sequential focus navigation, and if so, what its
relative order should be.</p>
</dd>
<dt id="negative-tabindex">If the value is a negative integer</dt>
<dd>
<p>The user agent must allow the element to be focused, but should
not allow the element to be reached using sequential focus
navigation.</p>
</dd>
<dt>If the value is a zero</dt>
<dd>
<p>The user agent must allow the element to be focused, should
allow the element to be reached using sequential focus navigation,
and should follow platform conventions to determine the element's
relative order.</p>
</dd>
<dt>If the value is greater than zero</dt>
<dd>
<p>The user agent must allow the element to be focused, should
allow the element to be reached using sequential focus navigation,
and should place the element in the sequential focus navigation
order so that it is:</p>
<ul>
<li>before any focusable element whose <code
title="attr-tabindex">tabindex</code> attribute has been
omitted or whose value, when parsed, returns an error,</li>
<li>before any focusable element whose <code
title="attr-tabindex">tabindex</code> attribute has a value equal
to or less than zero,</li>
<li>after any element whose <code
title="attr-tabindex">tabindex</code> attribute has a value
greater than zero but less than the value of the <code
title="attr-tabindex">tabindex</code> attribute on the
element,</li>
<li>after any element whose <code
title="attr-tabindex">tabindex</code> attribute has a value equal
to the value of the <code title="attr-tabindex">tabindex</code>
attribute on the element but that is earlier in the document in
<span>tree order</span> than the element,</li>
<li>before any element whose <code
title="attr-tabindex">tabindex</code> attribute has a value equal
to the value of the <code title="attr-tabindex">tabindex</code>
attribute on the element but that is later in the document in
<span>tree order</span> than the element, and</li>
<li>before any element whose <code
title="attr-tabindex">tabindex</code> attribute has a value
greater than the value of the <code
title="attr-tabindex">tabindex</code> attribute on the
element.</li>
</ul>
</dd>
</dl>
<p>An element is <dfn>specially focusable</dfn> if the <code
title="attr-tabindex">tabindex</code> attribute's definition above
defines the element to be focusable.</p>
<p>An element that is <span>specially focusable</span> but does not
otherwise have an <span>activation behavior</span> defined has an
<span>activation behavior</span> that does nothing.</p>
<p class="note">This means that an element that is only focusable
because of its <code title="attr-tabindex">tabindex</code> attribute
will fire a <code title="event-click">click</code> event in response
to a non-mouse activation (e.g. hitting the "enter" key while the
element is focused).</p>
<p>The <dfn title="dom-tabIndex"><code>tabIndex</code></dfn> IDL
attribute must <span>reflect</span> the value of the <code
title="attr-tabindex">tabindex</code> content attribute. If the
attribute is not present, or parsing its value returns an error,
then the IDL attribute must return 0 for elements that are focusable
and −1 for elements that are not focusable.</p>
</div>
<div class="impl">
<h4 id="focus-management">Focus management</h4>
<p>An element is <dfn>focusable</dfn> if the user agent's default
behavior allows it to be focusable or if the element is
<span>specially focusable</span>, but only if the element is either
<span>being rendered</span> or <!-- CANVAS-FOCUS-FALLBACK --> is a
descendant of a <code>canvas</code> element that
<span>represents</span> <span>embedded content</span>.</p>
<p>User agents should make the following elements
<span>focusable</span>, unless platform conventions dictate
otherwise:</p>
<ul>
<li><code>a</code> elements that have an <code
title="attr-hyperlink-href">href</code> attribute</li>
<li><code>link</code> elements that have an <code
title="attr-link-href">href</code> attribute</li>
<li><code>button</code> elements that are not <span
title="concept-fe-disabled">disabled</span></li>
<li><code>input</code> elements whose <code
title="attr-input-type">type</code> attribute are not in the
<span title="attr-input-type-hidden">Hidden</span> state and that
are not <span title="concept-fe-disabled">disabled</span></li>
<li><code>select</code> elements that are not <span
title="concept-fe-disabled">disabled</span></li>
<li><code>textarea</code> elements that are not <span
title="concept-fe-disabled">disabled</span></li>
<li><code>command</code> elements that do not have a <code
title="attr-command-disabled">disabled</code> attribute</li>
<li>Elements with a <code title="attr-draggable">draggable</code>
attribute set, if that would enable the user agent to allow the
user to begin a drag operations for those elements without the use
of a pointing device</li>
</ul>
<p>In addition, each shape that is generated for an
<code>area</code> element should be <span>focusable</span>, unless
platform conventions dictate otherwise. (A single <code>area</code>
element can correspond to multiple shapes, since image maps can be
reused with multiple images on a page.)</p>
<hr>
<p>The <dfn>focusing steps</dfn> are as follows:</p>
<ol>
<li><p>If focusing the element will remove the focus from another
element, then run the <span>unfocusing steps</span> for that
element.</p></li>
<li>
<p>Make the element the currently focused element in its
<span>top-level browsing context</span>.</p>
<p>Some elements, most notably <code>area</code>, can correspond
to more than one distinct focusable area. If a particular area was
indicated when the element was focused, then that is the area that
must get focus; otherwise, e.g. when using the <code
title="dom-focus">focus()</code> method, the first such region in
tree order is the one that must be focused.</p>
</li>
<li><p><span>Fire a simple event</span> named <code
title="event-focus">focus</code> at the element.</p></li>
</ol>
<p>User agents must synchronously run the <span>focusing
steps</span> for an element whenever the user moves the focus to a
<span>focusable</span> element.</p>
<p>The <dfn>unfocusing steps</dfn> are as follows:</p>
<ol>
<li><p>If the element is an <code>input</code> element, and the
<code title="event-input-change">change</code> event applies to the
element, and the element does not have a defined <span>activation
behavior</span>, and the user has changed the element's <span
title="concept-fe-value">value</span> or its list of <span
title="concept-input-type-file-selected">selected files</span>
while the control was focused without committing that change, then
<span>fire a simple event</span> that bubbles named <code
title="event-change">change</code> at the element, then
<span>broadcast <code title="event-formchange">formchange</code>
events</span> at the element's <span>form owner</span>.</p>
<li><p>Unfocus the element.</p></li>
<li><p><span>Fire a simple event</span> named <code
title="event-blur">blur</code> at the element.</p></li>
</ol>
<p>When an element that is focused stops being a
<span>focusable</span> element, or stops being focused without
another element being explicitly focused in its stead, the user
agent should synchronously run the <span>focusing steps</span> for
<span>the body element</span>, if there is one; if there is not,
then the user agent should synchronously run the <span>unfocusing
steps</span> for the affected element only.</p>
<p class="example">For example, this might happen because the
element is removed from its <code>Document</code>, or has a <code
title="attr-hidden">hidden</code> attribute added. It would also
happen to an <code>input</code> element when the element gets <span
title="concept-fe-disabled">disabled</span>.</p>
</div>
<h4>Document-level focus APIs</h4>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-activeElement">activeElement</code></dt>
<dd>
<p>Returns the currently focused element.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-hasFocus">hasFocus</code>()</dt>
<dd>
<p>Returns true if the document has focus; otherwise, returns false.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-window-focus">focus</code>()</dt>
<dd>
<p>Focuses the window. Use of this method is discouraged. Allow the user to control window focus instead.</p>
</dd>
<dt><var title="">window</var> . <code title="dom-window-blur">blur</code>()</dt>
<dd>
<p>Unfocuses the window. Use of this method is discouraged. Allow the user to control window focus instead.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-document-activeElement"><code>activeElement</code></dfn>
attribute on <code>DocumentHTML</code> objects must return the
element in the document that is focused. If no element in the
<code>Document</code> is focused, this must return <span>the body
element</span>.</p>
<p>The <dfn
title="dom-document-hasFocus"><code>hasFocus()</code></dfn> method
on <code>DocumentHTML</code> objects must return true if the
document's <span>browsing context</span> is focused, and all its
<span title="ancestor browsing context">ancestor browsing
contexts</span> are also focused, and the <span>top-level browsing
context</span> has the <i>system focus</i>.</p>
<p>The <dfn title="dom-window-focus"><code>focus()</code></dfn>
method on the <code>Window</code> object, when invoked, provides a
hint to the user agent that the script believes the user might be
interested in the contents of the <span>browsing context</span> of
the <code>Window</code> object on which the method was invoked.</p>
<p>User agents are encouraged to have this <code
title="dom-window-focus">focus()</code> method trigger some kind of
notification.</p>
<p>The <dfn title="dom-window-blur"><code>blur()</code></dfn> method
on the <code>Window</code> object, when invoked, provides a hint to
the user agent that the script believes the user probably is not
currently interested in the contents of the <span>browsing
context</span> of the <code>Window</code> object on which the method
was invoked, but that the contents might become interesting again in
the future.</p>
<p>User agents are encouraged to ignore calls to this <code
title="dom-window-blur">blur()</code> method entirely.</p>
<p class="note">Historically the <code
title="dom-window-blur">focus()</code> and <code
title="dom-window-blur">blur()</code> methods actually affected the
system focus, but hostile sites widely abuse this behavior to the
user's detriment.</p>
</div>
<h4>Element-level focus APIs</h4>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-focus">focus</code>()</dt>
<dd>
<p>Focuses the element.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-blur">blur</code>()</dt>
<dd>
<p>Unfocuses the element. Use of this method is discouraged. Focus another element instead.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-focus"><code>focus()</code></dfn> method,
when invoked, must run the following algorithm:</p>
<ol>
<li><p>If the element is marked as <i>locked for focus</i>, then abort
these steps.</p></li>
<li><p>If the element is not <span>focusable</span>, then abort these
steps.</p></li>
<li><p>Mark the element as <dfn>locked for focus</dfn>.</p></li>
<li><p>If the element is not already focused, run the <span>focusing
steps</span> for the element.</p></li>
<li><p>Unmark the element as <i>locked for focus</i>.</p></li>
</ol>
<p>The <dfn title="dom-blur"><code>blur()</code></dfn> method, when
invoked, should run the <span>focusing steps</span> for <span>the
body element</span>, if there is one; if there is not, then it
should run the <span>unfocusing steps</span> for the element on
which the method was called instead. User agents may selectively or
uniformly ignore calls to this method for usability reasons.</p>
</div>
<h3>The <dfn title="attr-accesskey"><code>accesskey</code></dfn> attribute</h3>
<p>All <span>HTML elements</span> may have the <code
title="attr-accesskey">accesskey</code> content attribute set. The
<code title="attr-accesskey">accesskey</code> attribute's value is
used by the user agent as a guide for creating a keyboard shortcut
that activates or focuses the element.</p>
<p>If specified, the value must be an <span>ordered set of unique
space-separated tokens</span>, each of which must be exactly one
Unicode code point in length.</p>
<div class="impl">
<p>An element's <dfn>assigned access key</dfn> is a key combination
derived from the element's <code
title="attr-accesskey">accesskey</code> content attribute as
follows:</p>
<ol>
<li><p>If the element has no <code
title="attr-accesskey">accesskey</code> attribute, then skip to the
<i>fallback</i> step below.</p></li>
<li><p>Otherwise, the user agent must must <span title="split a
string on spaces">split the attribute's value on spaces</span>, and
let <var title="">keys</var> be the resulting tokens.</p></li>
<li>
<p>For each value in <var title="">keys</var> in turn, in the
order the tokens appeared in the attribute's value, run the
following substeps:</p>
<ol>
<li><p>If the value is not a string exactly one Unicode code
point in length, then skip the remainder of these steps for this
value.</p></li>
<li><p>If the value does not correspond to a key on the system's
keyboard, then skip the remainder of these steps for this
value.</p></li>
<li><p>If the user agent can find a combination of modifier keys
that, with the key that corresponds to the value given in the
attribute, can be used as a shortcut key, then the user agent may
assign that combination of keys as the element's <span>assigned
access key</span> and abort these steps.</p></li>
</ol>
</li>
<li><p><i>Fallback</i>: Optionally, the user agent may assign a key
combination of its choosing as the element's <span>assigned access
key</span> and then abort these steps.</p></li>
<li><p>If this step is reached, the element has no <span>assigned
access key</span>.</p></li>
</ol>
<p>Once a user agent has selected and assigned an access key for an
element, the user agent should not change the element's
<span>assigned access key</span> unless the <code
title="attr-accesskey">accesskey</code> content attribute is changed
or the element is moved to another <code>Document</code>.</p>
<p>When the user presses the key combination corresponding to the
<span>assigned access key</span> for an element, if the element
<span title="concept-command">defines a command</span>, and the
command's <span title="command-facet-HiddenState">Hidden
State</span> facet is false (visible), and the command's <span
title="command-facet-DisabledState">Disabled State</span> facet is
also false (enabled), then the user agent must trigger the <span
title="command-facet-Action">Action</span> of the command.</p>
<p>User agents may expose elements that have an <code
title="attr-accesskey">accesskey</code> attribute in other ways as
well, e.g. in a menu displayed in response to a specific key
combination.</p>
</div>
<div class="impl">
<p>The <dfn title="dom-accessKey"><code>accessKey</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-accesskey">accesskey</code> content attribute.</p>
<p>The <dfn
title="dom-accessKeyLabel"><code>accessKeyLabel</code></dfn> IDL
attribute must return a string that represents the element's
<span>assigned access key</span>, if any. If the element does not
have one, then the IDL attribute must return the empty string.</p>
</div>
<div class="example">
<p>In the following example, a variety of links are given with
access keys so that keyboard users familiar with the site can
more quickly navigate to the relevant pages:</p>
<pre><nav>
<p>
<a title="Consortium Activities" accesskey="A" href="/Consortium/activities">Activities</a> |
<a title="Technical Reports and Recommendations" accesskey="T" href="/TR/">Technical Reports</a> |
<a title="Alphabetical Site Index" accesskey="S" href="/Consortium/siteindex">Site Index</a> |
<a title="About This Site" accesskey="B" href="/Consortium/">About Consortium</a> |
<a title="Contact Consortium" accesskey="C" href="/Consortium/contact">Contact</a>
</p>
</nav></pre>
</div>
<div class="example">
<p>In the following example, the search field is given two possible
access keys, "s" and "0" (in that order). A user agent on a device
with a full keyboard might pick
<kbd><kbd>Ctrl</kbd>+<kbd>Alt</kbd>+<kbd>S</kbd></kbd> as the
shortcut key, while a user agent on a small device with just a
numeric keypad might pick just the plain unadorned key
<kbd><kbd>0</kbd></kbd>:</p>
<pre><form action="/search">
<label>Search: <input type="search" name="q" accesskey="s 0"></label>
<input type="submit">
</form></pre>
</div>
<div class="example">
<p>In the following example, a button has possible access keys
described. A script then tries to update the button's label to
advertise the key combination the user agent selected.</p>
<pre><input type=submit accesskey="N @ 1" value="Compose">
...
<script>
function labelButton(button) {
if (button.accessKeyLabel)
button.value += ' (' + button.accessKeyLabel + ')';
}
var inputs = document.getElementsByTagName('input');
for (var i = 0; i < inputs.length; i += 1) {
if (inputs[i].type == "submit")
labelButton(inputs[i]);
}
</script></pre>
<p>On one user agent, the button's label might become
"<samp>Compose (⌘N)</samp>". On another, it might become
"<samp>Compose (Alt+⇧+1)</samp>". If the user agent doesn't
assign a key, it will be just "<samp>Compose</samp>". The exact
string depends on what the <span>assigned access key</span> is, and
on how the user agent represents that key combination.</p>
</div>
<h3 id="selection">The text selection APIs</h3>
<p>Every <span>browsing context</span> has <dfn title="the
selection">a selection</dfn>. The selection can be empty, and the
selection can have more than one range (a disjointed selection). The
user agent should allow the user to change the selection. User
agents are not required to let the user select more than one range,
and may collapse multiple ranges in the selection to a single range
when the user interacts with the selection. (But, of course, the
user agent may let the user create selections with multiple
ranges.)</p>
<p>This one selection must be shared by all the content of the
browsing context (though not by nested <span title="browsing
context">browsing contexts</span>), including any editing hosts in
the document. (Editing hosts that are not inside a document cannot
have a selection.)</p>
<div class="impl">
<p>If the selection is empty (collapsed, so that it has only one
segment and that segment's start and end points are the same) then
the selection's position should equal the caret position. When the
selection is not empty, this specification does not define the caret
position; user agents should follow platform conventions in deciding
whether the caret is at the start of the selection, the end of the
selection, or somewhere else.</p>
<p>On some platforms (such as those using Wordstar editing
conventions), the caret position is totally independent of the start
and end of the selection, even when the selection is empty. On such
platforms, user agents may ignore the requirement that the cursor
position be linked to the position of the selection altogether.</p>
</div>
<p>Mostly for historical reasons, in addition to the <span>browsing
context</span>'s <span title="the selection">selection</span>, each
<code>textarea</code> and <code>input</code> element has an
independent selection. These are the <dfn title="text field
selection">text field selections</dfn>.</p>
<div class="impl">
<p>User agents may selectively ignore attempts to use the API to
adjust the selection made after the user has modified the
selection. For example, if the user has just selected part of a
word, the user agent could ignore attempts to use the API call to
immediately unselect the selection altogether, but could allow
attempts to change the selection to select the entire word.</p>
<p>User agents may also allow the user to create selections that are
not exposed to the API.</p>
</div>
<!-- v2DATAGRID v2DGS:
<p>The <code>datagrid</code> and <code>select</code> elements also
have selections, indicating which items have been picked by the
user. These are not discussed in this section.</p>
-->
<p>The <code>select</code> element also has a selection, indicating
which items have been picked by the user. This is not discussed in
this section.</p>
<p class="note">This specification does not specify how selections
are presented to the user. The Selectors specification, in
conjunction with CSS, can be used to style text selections using the
<code title="selector-selection">::selection</code>
pseudo-element. <a href="#refsSELECTORS">[SELECTORS]</a> <a
href="#refsCSS">[CSS]</a></p>
<h4 id="documentSelection">APIs for the browsing context selection</h4>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-getSelection">getSelection</code>()</dt>
<dt><var title="">document</var> . <code title="dom-document-getSelection">getSelection</code>()</dt>
<dd>
<p>Returns the <code>Selection</code> object for the window, which
stringifies to the text of the current selection.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-getSelection"><code>getSelection()</code></dfn> method on
the <code>Window</code> interface must return the
<code>Selection</code> object representing <span>the
selection</span> of that <code>Window</code> object's
<span>browsing context</span>.
<p>For historical reasons, the <dfn
title="dom-document-getSelection"><code>getSelection()</code></dfn>
method on the <code>HTMLDocument</code> interface must return the
same <code>Selection</code> object.</p>
</div>
<pre class="idl">interface <dfn>Selection</dfn> {
readonly attribute Node <span title="dom-selection-anchorNode">anchorNode</span>;
readonly attribute long <span title="dom-selection-anchorOffset">anchorOffset</span>;
readonly attribute Node <span title="dom-selection-focusNode">focusNode</span>;
readonly attribute long <span title="dom-selection-focusOffset">focusOffset</span>;
readonly attribute boolean <span title="dom-selection-isCollapsed">isCollapsed</span>;
void <span title="dom-selection-collapse">collapse</span>(in Node parentNode, in long offset);
void <span title="dom-selection-collapseToStart">collapseToStart</span>();
void <span title="dom-selection-collapseToEnd">collapseToEnd</span>();
void <span title="dom-selection-selectAllChildren">selectAllChildren</span>(in Node parentNode);
void <span title="dom-selection-deleteFromDocument">deleteFromDocument</span>();
readonly attribute long <span title="dom-selection-rangeCount">rangeCount</span>;
Range <span title="dom-selection-getRangeAt">getRangeAt</span>(in long index);
void <span title="dom-selection-addRange">addRange</span>(in Range range);
void <span title="dom-selection-removeRange">removeRange</span>(in Range range);
void <span title="dom-selection-removeAllRanges">removeAllRanges</span>();
<span title="dom-selection-toString">stringifier</span> DOMString ();
};</pre>
<!--
See also:
http://lxr.mozilla.org/mozilla/source/content/base/public/nsISelection.idl
This spec doesn't have everything from there yet, in particular
selectionLanguageChange() and containsNode() are missing. They are missing
because I couldn't work out how to define them in terms of Ranges.
I also haven't included extend():
void <span title="dom-selection-extend">extend</span>(in Node parentNode, in long offset);
// raise if no range
// raise WRONG_DOCUMENT_ERR if parentNode not in document
// do something
...mostly because I can't work out how to describe what it does quickly.
-->
<p>The <code>Selection</code> interface is represents a list of
<code>Range</code> objects. The first item in the list has index 0,
and the last item has index <var title="">count</var>-1, where
<var title="">count</var> is the number of ranges in the list. <a
href="#refsDOMRANGE">[DOMRANGE]</a></p>
<p>All of the members of the <code>Selection</code> interface are
defined in terms of operations on the <code>Range</code> objects
represented by this object. These operations can raise exceptions,
as defined for the <code>Range</code> interface; this can therefore
result in the members of the <code>Selection</code> interface
raising exceptions as well, in addition to any explicitly called out
below.</p>
<dl class="domintro">
<dt><var title="">selection</var> . <code title="dom-selection-anchorNode">anchorNode</code></dt>
<dd>
<p>Returns the element that contains the start of the selection.</p>
<p>Returns null if there's no selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-anchorOffset">anchorOffset</code></dt>
<dd>
<p>Returns the offset of the start of the selection relative to the element that contains the start of the selection.</p>
<p>Returns 0 if there's no selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-focusNode">focusNode</code></dt>
<dd>
<p>Returns the element that contains the end of the selection.</p>
<p>Returns null if there's no selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-focusOffset">focusOffset</code></dt>
<dd>
<p>Returns the offset of the end of the selection relative to the element that contains the end of the selection.</p>
<p>Returns 0 if there's no selection.</p>
</dd>
<dt><var title="">collapsed</var> = <var title="">selection</var> . <code title="dom-selection-isCollapsed">isCollapsed</code>()</dt>
<dd>
<p>Returns true if there's no selection or if the selection is empty. Otherwise, returns false.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-collapsed">collapsed</code>(<var title="">parentNode</var>, <var title="">offset</var>)</dt>
<dd>
<p>Replaces the selection with an empty one at the given position.</p>
<p>Throws a <code>WRONG_DOCUMENT_ERR</code> exception if the given node is in a different document.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-collapseToStart">collapseToStart</code>()</dt>
<dd>
<p>Replaces the selection with an empty one at the position of the start of the current selection.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if there is no selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-collapseToEnd">collapseToEnd</code>()</dt>
<dd>
<p>Replaces the selection with an empty one at the position of the end of the current selection.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if there is no selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-selectAllChildren">selectAllChildren</code>(<var title="">parentNode</var>)</dt>
<dd>
<p>Replaces the selection with one that contains all the contents of the given element.</p>
<p>Throws a <code>WRONG_DOCUMENT_ERR</code> exception if the given node is in a different document.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-deleteFromDocument">deleteFromDocument</code>()</dt>
<dd>
<p>Deletes the selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-rangeCount">rangeCount</code></dt>
<dd>
<p>Returns the number of ranges in the selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-getRangeAt">getRangeAt</code>(<var title="">index</var>)</dt>
<dd>
<p>Returns the given range.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> exception if the value is out of range.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-addRange">addRange</code>(<var title="">range</var>)</dt>
<dd>
<p>Adds the given range to the selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-removeRange">removeRange</code>(<var title="">range</var>)</dt>
<dd>
<p>Removes the given range from the selection, if the range was one of the ones in the selection.</p>
</dd>
<dt><var title="">selection</var> . <code title="dom-selection-removeAllRanges">removeAllRanges</code>()</dt>
<dd>
<p>Removes all the ranges in the selection.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-selection-anchorNode"><code>anchorNode</code></dfn>
attribute must return the value returned by the <code
title="">startContainer</code> attribute of the last
<code>Range</code> object in the list, or null if the list is
empty.</p>
<p>The <dfn
title="dom-selection-anchorOffset"><code>anchorOffset</code></dfn>
attribute must return the value returned by the <code
title="">startOffset</code> attribute of the last <code>Range</code>
object in the list, or 0 if the list is empty.</p>
<p>The <dfn
title="dom-selection-focusNode"><code>focusNode</code></dfn>
attribute must return the value returned by the <code
title="">endContainer</code> attribute of the last
<code>Range</code> object in the list, or null if the list is
empty.</p>
<p>The <dfn
title="dom-selection-focusOffset"><code>focusOffset</code></dfn>
attribute must return the value returned by the <code
title="">endOffset</code> attribute of the last <code>Range</code>
object in the list, or 0 if the list is empty.</p>
<p>The <dfn
title="dom-selection-isCollapsed"><code>isCollapsed</code></dfn>
attribute must return true if there are zero ranges, or if there is
exactly one range and its <code title="">collapsed</code> attribute
is itself true. Otherwise it must return false.</p>
<p>The <dfn title="dom-selection-collapse"><code>collapse(<var
title="">parentNode</var>, <var title="">offset</var>)</code></dfn>
method must raise a <code>WRONG_DOCUMENT_ERR</code> DOM exception if
<var title="">parentNode</var>'s <code>Document</code> is not the
<code>HTMLDocument</code> object with which the
<code>Selection</code> object is associated. Otherwise it is, and
the method must remove all the ranges in the <code>Selection</code>
list, then create a new <code>Range</code> object, add it to the
list, and invoke its <code title="">setStart()</code> and <code
title="">setEnd()</code> methods with the <var
title="">parentNode</var> and <var title="">offset</var> values as
their arguments.</p>
<p>The <dfn
title="dom-selection-collapseToStart"><code>collapseToStart()</code></dfn>
method must raise an <code>INVALID_STATE_ERR</code> DOM exception if
there are no ranges in the list. Otherwise, it must invoke the <code
title="dom-selection-collapse">collapse()</code> method with the
<code title="">startContainer</code> and <code
title="">startOffset</code> values of the first <code>Range</code>
object in the list as the arguments.</p>
<p>The <dfn
title="dom-selection-collapseToEnd"><code>collapseToEnd()</code></dfn>
method must raise an <code>INVALID_STATE_ERR</code> DOM exception if
there are no ranges in the list. Otherwise, it must invoke the <code
title="dom-selection-collapse">collapse()</code> method with the
<code title="">endContainer</code> and <code
title="">endOffset</code> values of the last <code>Range</code>
object in the list as the arguments.</p>
<p>The <dfn
title="dom-selection-selectAllChildren"><code>selectAllChildren(<var title="">parentNode</var>)</code></dfn>
method must invoke the <code
title="dom-selection-collapse">collapse()</code> method with the
<var title="">parentNode</var> value as the first argument and 0 as the
second argument, and must then invoke the <code
title="">selectNodeContents()</code> method on the first (and only)
range in the list with the <var title="">parentNode</var> value as the
argument.</p>
<p>The <dfn
title="dom-selection-deleteFromDocument"><code>deleteFromDocument()</code></dfn>
method must invoke the <code title="">deleteContents()</code> method
on each range in the list, if any, from first to last.</p>
<p>The <dfn
title="dom-selection-rangeCount"><code>rangeCount</code></dfn>
attribute must return the number of ranges in the list.</p>
<p>The <dfn
title="dom-selection-getRangeAt"><code>getRangeAt(<var title="">index</var>)</code></dfn>
method must return the <var title="">index</var>th range in the list. If
<var title="">index</var> is less than zero or greater or equal to the value
returned by the <code
title="dom-selection-rangeCount">rangeCount</code> attribute, then
the method must raise an <code>INDEX_SIZE_ERR</code> DOM
exception.</p>
<p>The <dfn
title="dom-selection-addRange"><code>addRange(<var title="">range</var>)</code></dfn>
method must add the given <var title="">range</var> Range object to the list
of selections, at the end (so the newly added range is the new last
range). Duplicates are not prevented; a range may be added more than
once in which case it appears in the list more than once, which (for
example) will cause <span
title="dom-selection-toString">stringification</span> to return the
range's text twice.</p>
<p>The <dfn
title="dom-selection-removeRange"><code>removeRange(<var title="">range</var>)</code></dfn>
method must remove the first occurrence of <var title="">range</var> in the
list of ranges, if it appears at all.</p>
<p>The <dfn
title="dom-selection-removeAllRanges"><code>removeAllRanges()</code></dfn>
method must remove all the ranges from the list of ranges, such that
the <code title="dom-selection-rangeCount">rangeCount</code>
attribute returns 0 after the <code
title="dom-selection-removeAllRanges">removeAllRanges()</code>
method is invoked (and until a new range is added to the list,
either through this interface or via user interaction).</p>
<p>Objects implementing this interface must <dfn
title="dom-selection-toString">stringify</dfn> to a concatenation
of the results of invoking the <code title="">toString()</code>
method of the <code>Range</code> object on each of the ranges of the
selection, in the order they appear in the list (first to last).</p>
</div>
<div class="example">
<p>In the following document fragment, the emphasized parts
indicate the selection.</p>
<pre><p>The cute girl likes <em>the </em><cite><em>Oxford English</em> Dictionary</cite>.</p></pre>
<p>If a script invoked <code
title="">window.getSelection().toString()</code>, the return value
would be "<code>the Oxford English</code>".</p>
</div>
<!-- v2DATAGRID v2DGS:
<p class="note">The <code>Selection</code> interface has no relation
to the <code>DataGridSelection</code> interface.</p>
-->
<h4 id="textFieldSelection">APIs for the text field selections</h4>
<!-- v2 idea: DOM Range APIs to expose the textarea/input edited
value (ack martijnw) -->
<p>The <code>input</code> and <code>textarea</code> elements define
the following members in their DOM interfaces for handling their
text selection:</p>
<pre class="idl extract"> void <span title="dom-textarea/input-select">select</span>();
attribute unsigned long <span title="dom-textarea/input-selectionStart">selectionStart</span>;
attribute unsigned long <span title="dom-textarea/input-selectionEnd">selectionEnd</span>;
void <span title="dom-textarea/input-setSelectionRange">setSelectionRange</span>(in unsigned long start, in unsigned long end);</pre>
<!-- v2: also add textLength? it seems to be widely used -->
<p>These methods and attributes expose and control the selection of
<code>input</code> and <code>textarea</code> text fields.</p>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-textarea/input-select">select</code>()</dt>
<dd>
<p>Selects everything in the text field.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-textarea/input-selecionStart">selectionStart</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the offset to the start of the selection.</p>
<p>Can be set, to change the start of the selection.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-textarea/input-selecionEnd">selectionEnd</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the offset to the end of the selection.</p>
<p>Can be set, to change the end of the selection.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-textarea/input-setSelectionRange">setSelectionRange</code>(<var title="">start</var>, <var title="">end</var>)</dt>
<dd>
<p>Changes the selection to cover the given substring.</p>
</dd>
</dl>
<div class="impl">
<p>When these methods and attributes are used with
<code>input</code> elements while they don't apply, they must raise
an <code>INVALID_STATE_ERR</code> exception. Otherwise, they must
act as described below.</p>
<p>The <dfn
title="dom-textarea/input-select"><code>select()</code></dfn> method
must cause the contents of the text field to be fully selected.</p>
<p>The <dfn
title="dom-textarea/input-selectionStart"><code>selectionStart</code></dfn>
attribute must, on getting, return the offset (in logical order) to
the character that immediately follows the start of the
selection. If there is no selection, then it must return the offset
(in logical order) to the character that immediately follows the
text entry cursor.</p>
<p>On setting, it must act as if the <code
title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>
method had been called, with the new value as the first argument,
and the current value of the <code
title="dom-textarea/input-selectionEnd">selectionEnd</code>
attribute as the second argument, unless the current value of the
<code title="dom-textarea/input-selectionEnd">selectionEnd</code> is
less than the new value, in which case the second argument must also
be the new value.</p>
<p>The <dfn
title="dom-textarea/input-selectionEnd"><code>selectionEnd</code></dfn>
attribute must, on getting, return the offset (in logical order) to
the character that immediately follows the end of the selection. If
there is no selection, then it must return the offset (in logical
order) to the character that immediately follows the text entry
cursor.</p>
<p>On setting, it must act as if the <code
title="dom-textarea/input-setSelectionRange">setSelectionRange()</code>
method had been called, with the current value of the <code
title="dom-textarea/input-selectionStart">selectionStart</code>
attribute as the first argument, and new value as the second
argument.</p>
<p>The <dfn
title="dom-textarea/input-setSelectionRange"><code>setSelectionRange(<var
title="">start</var>, <var title="">end</var>)</code></dfn> method
must set the selection of the text field to the sequence of
characters starting with the character at the <var
title="">start</var>th position (in logical order) and ending with
the character at the <span title="">(<var
title="">end</var>-1)</span>th position. Arguments greater than the
length of the value in the text field must be treated as pointing at
the end of the text field. If <var title="">end</var> is less than
or equal to <var title="">start</var> then the start of the
selection and the end of the selection must both be placed
immediately before the character with offset <var
title="">end</var>. In UAs where there is no concept of an empty
selection, this must set the cursor to be just before the character
with offset <var title="">end</var>.</p>
</div>
<div class="example">
<p>To obtain the currently selected text, the following JavaScript
suffices:</p>
<pre>var selectionText = control.value.substring(control.selectionStart, control.selectionEnd);</pre>
<p>...where <var title="">control</var> is the <code>input</code>
or <code>textarea</code> element.</p>
</div>
<p>Characters with no visible rendering, such as U+200D ZERO WIDTH
JOINER, still count as characters. Thus, for instance, the selection
can include just an invisible character, and the text insertion
cursor can be placed to one side or another of such a character.</p>
<h3 id="contenteditable">The <code
title="attr-contenteditable">contenteditable</code> attribute</h3>
<p>The <dfn
title="attr-contenteditable"><code>contenteditable</code></dfn>
attribute is an <span>enumerated attribute</span> whose keywords are
the empty string, <code title="">true</code>, and <code
title="">false</code>. The empty string and the <code
title="">true</code> keyword map to the <i>true</i> state. The <code
title="">false</code> keyword maps to the <i>false</i> state. In
addition, there is a third state, the <i>inherit</i> state, which is
the <i>missing value default</i> (and the <i>invalid value
default</i>).</p>
<p>The <i>true</i> state indicates that the element is editable. The
<i>inherit</i> state indicates that the element is editable if its
parent is. The <i>false</i> state indicates that the element is not
editable.</p>
<div class="impl">
<p>Specifically, if an <span title="HTML elements">HTML
element</span> has a <code
title="attr-contenteditable">contenteditable</code> attribute set to
the true state, or it has its <code
title="attr-contenteditable">contenteditable</code> attribute set to
the inherit state and if its nearest ancestor <span title="HTML
elements">HTML element</span> with the <code
title="attr-contenteditable">contenteditable</code> attribute set to
a state other than the inherit state has its attribute set to the
true state, or if it and its ancestors all have their <code
title="attr-contenteditable">contenteditable</code> attribute set to
the inherit state but the <code>Document</code> has <code
title="dom-document-designMode">designMode</code> enabled, then the
UA must treat the element as <dfn>editable</dfn> (as described
below).</p>
<p>Otherwise, either the <span title="HTML elements">HTML
element</span> has a <code
title="attr-contenteditable">contenteditable</code> attribute set to
the false state, or its <code
title="attr-contenteditable">contenteditable</code> attribute is set
to the inherit state and its nearest ancestor <span title="HTML
elements">HTML element</span> with the <code
title="attr-contenteditable">contenteditable</code> attribute set to
a state other than the inherit state has its attribute set to the
false state, or all its ancestors have their <code
title="attr-contenteditable">contenteditable</code> attribute set to
the inherit state and the <code>Document</code> itself has <code
title="dom-document-designMode">designMode</code> disabled; either
way, the element is not editable.</p>
</div>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-contentEditable">contentEditable</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns "<code title="">true</code>", "<code
title="">false</code>", or "<code title="">inherit</code>", based
on the state of the <code
title="attr-contenteditable">contenteditable</code> attribute.</p>
<p>Can be set, to change that state.</p>
<p>Throws a <code>SYNTAX_ERR</code> exception if the new value
isn't one of those strings.</p>
</dd>
<dt><var title="">element</var> . <code title="dom-isContentEditable">isContentEditable</code></dt>
<dd>
<p>Returns true if the element is editable; otherwise, returns false.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-contentEditable"><code>contentEditable</code></dfn> IDL
attribute, on getting, must return the string "<code
title="">true</code>" if the content attribute is set to the true
state, <code title="">false</code>" if the content attribute is set
to the false state, and "<code title="">inherit</code>"
otherwise. On setting, if the new value is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">inherit</code>" then the content attribute must be removed,
if the new value is an <span>ASCII case-insensitive</span> match for
the string "<code title="">true</code>" then the content attribute
must be set to the string "<code title="">true</code>", if the new
value is an <span>ASCII case-insensitive</span> match for the string
"<code title="">false</code>" then the content attribute must be set
to the string "<code title="">false</code>", and otherwise the
attribute setter must raise a <code>SYNTAX_ERR</code> exception.</p>
<p>The <dfn
title="dom-isContentEditable"><code>isContentEditable</code></dfn>
IDL attribute, on getting, must return true if the element is
<span>editable</span>, and false otherwise.</p>
<p>If an element is <span>editable</span> and its parent element is
not, or if an element is <span>editable</span> and it has no parent
element, then the element is an <dfn>editing host</dfn>. Editable
elements can be nested. User agents must make editing hosts
focusable (which typically means they enter the <span
title="attr-tabindex">tab order</span>). An editing host can contain
non-editable sections, these are handled as described below. An
editing host can contain non-editable sections that contain further
editing hosts.</p>
<p>When an editing host has focus, it must have a <dfn>caret
position</dfn> that specifies where the current editing position
is. It may also have a <span title="the
selection">selection</span>.</p>
<p class="note">How the caret and selection are represented depends
entirely on the UA.</p>
<!-- v2: would be useful to have a way to mark an element as
unremovable. -->
</div>
<div class="impl">
<h4>User editing actions</h4>
<p>There are several actions that the user agent should allow the
user to perform while the user is interacting with an editing
host. How exactly each action is triggered is not defined for every
action, but when it is not defined, suggested key bindings are
provided to guide implementors.</p>
<dl>
<dt>Move the caret</dt>
<dd><p>User agents must allow users to move the caret to any
position within an editing host, even into nested editable
elements. This could be triggered as the default action of <code
title="event-keydown">keydown</code> events with various key
identifiers and as the default action of <code
title="event-mousedown">mousedown</code> events.</p></dd>
<dt>Change the selection</dt>
<dd><p>User agents must allow users to change <span>the
selection</span> within an editing host, even into nested editable
elements. User agents may prevent selections from being made in
ways that cross from editable elements into non-editable elements
(e.g. by making each non-editable descendant atomically selectable,
but not allowing text selection within them). This could be
triggered as the default action of <code
title="event-keydown">keydown</code> events with various key
identifiers and as the default action of <code
title="event-mousedown">mousedown</code> events.</p></dd>
<dt id="contenteditable-insertText">Insert text</dt>
<dd><p>This action must be triggered as the default action of a
<code title="event-textInput">textInput</code> event, and may be
triggered by other commands as well. It must cause the user agent
to insert the specified text (given by the event object's <code
title="">data</code> attribute in the case of the <code
title="event-textInput">textInput</code> event) at the caret.</p>
<p>If the caret is positioned somewhere where <span>phrasing
content</span> is not allowed (e.g. inside an empty <code>ol</code>
element), then the user agent must not insert the text directly at
the caret position. In such cases the behavior is UA-dependent,
but user agents must not, in response to a request to insert text,
generate a DOM that is less conformant than the DOM prior to the
request.</p>
<p>User agents should allow users to insert new paragraphs into
elements that contains only content other than paragraphs.</p>
<div class="example">
<p>For example, given the markup:</p>
<pre><section>
<dl>
<dt> Ben </dt>
<dd> Goat </dd>
</dl>
</section></pre>
<p>...the user agent should allow the user to insert
<code>p</code> elements before and after the <code>dl</code>
element, as children of the <code>section</code> element.</p>
</div>
</dd>
<dt id="contenteditable-breakBlock">Break block</dt>
<dd><p>UAs should offer a way for the user to request that the
current paragraph be broken at the caret, e.g. as the default
action of a <code title="event-keydown">keydown</code> event whose
identifier is the "Enter" key and that has no modifiers set.</p>
<p>The exact behavior is UA-dependent, but user agents must not,
in response to a request to break a paragraph, generate a DOM that
is less conformant than the DOM prior to the request.</p></dd>
<dt id="contenteditable-br">Insert a line separator</dt>
<dd><p>UAs should offer a way for the user to request an explicit
line break at the caret position without breaking the paragraph,
e.g. as the default action of a <code
title="event-keydown">keydown</code> event whose identifier is the
"Enter" key and that has a shift modifier set. Line separators are
typically found within a poem verse or an address. To insert a line
break, the user agent must insert a <code>br</code> element.</p>
<p>If the caret is positioned somewhere where <span>phrasing
content</span> is not allowed (e.g. in an empty <code>ol</code>
element), then the user agent must not insert the <code>br</code>
element directly at the caret position. In such cases the behavior
is UA-dependent, but user agents must not, in response to a request
to insert a line separator, generate a DOM that is less conformant
than the DOM prior to the request.</p></dd>
<dt id="contenteditable-delete">Delete</dt>
<dd><p>UAs should offer a way for the user to delete text and
elements, including non-editable descendants, e.g. as the default
action of <code title="event-keydown">keydown</code> events whose
identifiers are "U+0008" or "U+007F".</p>
<p>Five edge cases in particular need to be considered carefully
when implementing this feature: backspacing at the start of an
element, backspacing when the caret is immediately after an
element, forward-deleting at the end of an element,
forward-deleting when the caret is immediately before an element,
and deleting a <span title="the selection">selection</span> whose
start and end points do not share a common parent node.</p>
<p>In any case, the exact behavior is UA-dependent, but user
agents must not, in response to a request to delete text or an
element, generate a DOM that is less conformant than the DOM prior
to the request.</p></dd>
<dt id="contenteditable-wrapSemantic">Insert, and wrap text in,
semantic elements</dt>
<dd><p>UAs should offer the user the ability to mark text and
paragraphs with semantics that HTML can express.</p>
<p>UAs should similarly offer a way for the user to insert empty
semantic elements to subsequently fill by entering text
manually.</p>
<p>UAs should also offer a way to remove those semantics from
marked up text, and to remove empty semantic element that have been
inserted.</p>
<p>In response to a request from a user to mark text up in italics,
user agents should use the <code>i</code> element to represent the
semantic. The <code>em</code> element should be used only if the
user agent is sure that the user means to indicate stress
emphasis.</p>
<p>In response to a request from a user to mark text up in bold,
user agents should use the <code>b</code> element to represent the
semantic. The <code>strong</code> element should be used only if
the user agent is sure that the user means to indicate
importance.</p>
<p>The exact behavior is UA-dependent, but user agents must not,
in response to a request to wrap semantics around some text or to
insert or remove a semantic element, generate a DOM that is less
conformant than the DOM prior to the request.</p></dd>
<dt>Select and move non-editable elements nested inside editing hosts</dt>
<dd><p>UAs should offer a way for the user to move images and other
non-editable parts around the content within an editing host. This
may be done using the <span>drag and drop</span> mechanism. User
agents must not, in response to a request to move non-editable
elements nested inside editing hosts, generate a DOM that is less
conformant than the DOM prior to the request.</p></dd>
<dt>Edit form controls nested inside editing hosts</dt>
<dd><p>When an <span>editable</span> form control is edited, the
changes must be reflected in both its current value <em>and</em>
its default value. For <code>input</code> elements this means
updating the <code
title="dom-input-defaultValue">defaultValue</code> IDL attribute as
well as the <code title="dom-input-value">value</code> IDL
attribute; for <code>select</code> elements it means updating the
<code>option</code> elements' <code
title="dom-option-defaultSelected">defaultSelected</code> IDL
attribute as well as the <code
title="dom-option-selected">selected</code> IDL attribute; for
<code>textarea</code> elements this means updating the <code
title="dom-textarea-defaultValue">defaultValue</code> IDL attribute
as well as the <code title="dom-textarea-value">value</code> IDL
attribute. (Updating the <code title="">default*</code> IDL
attributes causes content attributes to be updated as well.)</p></dd>
</dl>
<p>User agents may perform several commands per user request; for
example if the user selects a block of text and hits
<kbd><kbd>Enter</kbd></kbd>, the UA might interpret that as a
request to delete the content of <span>the selection</span> followed
by a request to break the paragraph at that position.</p>
<p>User agents may add <span>DOM changes</span> entries to the
<span>undo transaction history</span> of the <span>editing
host</span>'s <code>Document</code> object each time an action is
triggered.</p>
<p>All of the actions defined above, whether triggered by the user
or programmatically (e.g. by <code
title="dom-document-execCommand">execCommand()</code> commands),
must fire mutation events as appropriate.</p>
</div>
<h4>Making entire documents editable</h4>
<div class="impl">
<p>Documents have a <dfn id="designMode"
title="dom-document-designMode"><code>designMode</code></dfn>, which
can be either enabled or disabled.</p>
</div>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-designMode">designMode</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns "<code title="">on</code>" if the document is editable,
and "<code title="">off</code>" if it isn't.</p>
<p>Can be set, to change the document's current state.</p>
</dd>
</dl>
<div class="impl">
<p>The <code title="dom-document-designMode">designMode</code> IDL
attribute on the <code>Document</code> object takes two values,
"<code title="">on</code>" and "<code title="">off</code>". When it
is set, the new value must be compared in an <span>ASCII
case-insensitive</span> manner to these two values. If it matches
the "<code title="">on</code>" value, then <code
title="dom-document-designMode">designMode</code> must be enabled,
and if it matches the "<code title="">off</code>" value, then <code
title="dom-document-designMode">designMode</code> must be
disabled. Other values must be ignored.</p>
<p>When <code title="dom-document-designMode">designMode</code> is
enabled, the IDL attribute must return the value "<code
title="">on</code>", and when it is disabled, it must return the
value "<code title="">off</code>".</p>
<p>The last state set must persist until the document is destroyed
or the state is changed. Initially, documents must have their <code
title="dom-document-designMode">designMode</code> disabled.</p>
</div>
<h3>Spelling and grammar checking</h3>
<div class="impl">
<p>User agents can support the checking of spelling and grammar of
editable text, either in form controls (such as the value of
<code>textarea</code> elements), or in elements in an <span>editing
host</span> (using <code
title="attr-contenteditable">contenteditable</code>).</p>
<p>For each element, user agents must establish a <dfn
title="concept-spellcheck-default">default behavior</dfn>, either
through defaults or through preferences expressed by the user. There
are three possible default behaviors for each element:</p>
<dl>
<dt><dfn title="concept-spellcheck-default-true">true-by-default</dfn>
<dd>The element will be checked for spelling and grammar if its
contents are editable.
<dt><dfn title="concept-spellcheck-default-false">false-by-default</dfn>
<dd>The element will never be checked for spelling and grammar.
<dt><dfn title="concept-spellcheck-default-inherit">inherit-by-default</dfn>
<dd>The element's default behavior is the same as its parent
element's. Elements that have no parent element cannot have this as
their default behavior.
</dl>
<hr>
</div>
<p>The <dfn title="attr-spellcheck"><code>spellcheck</code></dfn>
attribute is an <span>enumerated attribute</span> whose keywords are
the empty string, <code title="">true</code> and <code
title="">false</code>. The empty string and the <code
title="">true</code> keyword map to the <i>true</i> state. The <code
title="">false</code> keyword maps to the <i>false</i> state. In
addition, there is a third state, the <i>default</i> state, which is
the <i>missing value default</i> (and the <i>invalid value
default</i>).</p>
<p>The <i>true</i> state indicates that the element is to have its
spelling and grammar checked. The <i>default</i> state indicates
that the element is to act according to a default behavior, possibly
based on the parent element's own <code
title="attr-spellcheck">spellcheck</code> state. The <i>false</i>
state indicates that the element is not to be checked.</p>
<div class="impl">
<hr>
</div>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-spellcheck">spellcheck</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns "<code title="">true</code>", "<code
title="">false</code>", or "<code title="">default</code>", based
on the state of the <code
title="attr-spellcheck">spellcheck</code> attribute.</p>
<p>Can be set, to change that state.</p>
<p>Throws a <code>SYNTAX_ERR</code> exception if the new value
isn't one of those strings.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-spellcheck"><code>spellcheck</code></dfn> IDL
attribute, on getting, must return the string "<code
title="">true</code>" if the content attribute is set to the true
state, <code title="">false</code>" if the content attribute is set
to the false state, and "<code title="">default</code>"
otherwise. On setting, if the new value is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">default</code>" then the content attribute must be removed,
if the new value is an <span>ASCII case-insensitive</span> match for
the string "<code title="">true</code>" then the content attribute
must be set to the string "<code title="">true</code>", if the new
value is an <span>ASCII case-insensitive</span> match for the string
"<code title="">false</code>" then the content attribute must be set
to the string "<code title="">false</code>", and otherwise the
attribute setter must raise a <code>SYNTAX_ERR</code> exception.</p>
<p class="note">The <code title="dom-spellcheck">spellcheck</code>
IDL attribute is not affected by user preferences that override the
<code title="attr-spellcheck">spellcheck</code> content attribute,
and therefore might not reflect the actual spellchecking state.</p>
<p>On setting, if the new value is true, then the element's <code
title="attr-spellcheck">spellcheck</code> content attribute must be
set to the literal string "<code title="">true</code>", otherwise it
must be set to the literal string "<code title="">false</code>".
<hr>
<p>User agents must only consider the following pieces of text as
checkable for the purposes of this feature:</p>
<ul>
<li>The value of <code>input</code> elements to which the <code
title="attr-input-readonly">readonly</code> attribute applies,
whose <code title="attr-input-type">type</code> attributes are not
in the <span title="attr-input-type-password">Password</span>
state, and that are not <i
title="concept-input-immutable">immutable</i> (i.e. that do not
have the <code title="attr-input-readonly">readonly</code>
attribute specified and that are not <span
title="concept-fe-disabled">disabled</span>).</li>
<li>The value of <code>textarea</code> elements that do not have a
<code title="attr-textarea-readonly">readonly</code> attribute and
that are not <span
title="concept-fe-disabled">disabled</span>.</li>
<li>Text in <span title="text node">text nodes</span> that are
children of <span>editable</span> elements.</li>
<li>Text in attributes of <span>editable</span> elements.</li>
</ul>
<p>For text that is part of a <span>text node</span>, the element
with which the text is associated is the element that is the
immediate parent of the first character of the word, sentence, or
other piece of text. For text in attributes, it is the attribute's
element. For the values of <code>input</code> and
<code>textarea</code> elements, it is the element itself.</p>
<p>To determine if a word, sentence, or other piece of text in an
applicable element (as defined above) is to have spelling- and/or
grammar-checking enabled, the UA must use the following
algorithm:</p>
<ol>
<!-- user override -->
<li>If the user has disabled the checking for this text, then the
checking is disabled.</li>
<li>Otherwise, if the user has forced the checking for this text to
always be enabled, then the checking is enabled.</li>
<!-- content attribute: on, off -->
<li>Otherwise, if the element with which the text is associated has
a <code title="attr-spellcheck">spellcheck</code> content
attribute, then: if that attribute is in the <i>true</i> state,
then checking is enabled; otherwise, if that attribute is in the
<i>false</i> state, then checking is disabled.</li>
<!-- inherit, if there is one to inherit from -->
<li>Otherwise, if there is an ancestor element with a <code
title="attr-spellcheck">spellcheck</code> content attribute that is
not in the <i>default</i> state, then: if the nearest such
ancestor's <code title="attr-spellcheck">spellcheck</code> content
attribute is in the <i>true</i> state, then checking is enabled;
otherwise, checking is disabled.</li>
<!-- default -->
<li>Otherwise, if the element's <span
title="concept-spellcheck-default">default behavior</span> is <span
title="concept-spellcheck-default-true">true-by-default</span>,
then checking is enabled.</li>
<li>Otherwise, if the element's <span
title="concept-spellcheck-default">default behavior</span> is <span
title="concept-spellcheck-default-false">false-by-default</span>,
then checking is disabled.</li>
<!-- default inheritance -->
<li>Otherwise, if the element's parent element has <em>its</em>
checking enabled, then checking is enabled.</li>
<li>Otherwise, checking is disabled.</li>
</ol>
<p>If the checking is enabled for a word/sentence/text, the user
agent should indicate spelling and/or grammar errors in that
text. User agents should take into account the other semantics given
in the document when suggesting spelling and grammar
corrections. User agents may use the language of the element to
determine what spelling and grammar rules to use, or may use the
user's preferred language settings. UAs should use
<code>input</code> element attributes such as <code
title="attr-input-pattern">pattern</code> to ensure that the
resulting value is valid, where possible.</p>
<p>If checking is disabled, the user agent should not indicate
spelling or grammar errors for that text.</p>
<div class="example">
<p>The element with ID "a" in the following example would be the
one used to determine if the word "Hello" is checked for spelling
errors. In this example, it would not be.</p>
<pre><div contenteditable="true">
<span spellcheck="false" id="a">Hell</span><em>o!</em>
</div></pre>
<p>The element with ID "b" in the following example would have
checking enabled (the leading space character in the attribute's
value on the <code>input</code> element causes the attribute to be
ignored, so the ancestor's value is used instead, regardless of the
default).</p>
<pre><p spellcheck="true">
<label>Name: <input spellcheck=" false" id="b"></label>
</p></pre>
</div>
</div>
<p class="note">This specification does not define the user
interface for spelling and grammar checkers. A user agent could
offer on-demand checking, could perform continuous checking while
the checking is enabled, or could use other interfaces.</p>
<h3 id="dnd"><dfn>Drag and drop</dfn></h3>
<!-- v2 ideas for drag and drop:
* being able to animate a drop target:
> To implement this with simple interface I've proposed, events
> should be handled either by existing elements (like list
> items that compare their size and position of dragged element
> to decide whether element should be dropped before or after)
> or handled by container that would probably need to calculate
> positions of it's children and create new element to show
> drop target. Smooth Mac-like drag'n'drop can be implemented
> by animating drop target's padding/margin. So that's quite a
> bit of code that's going to be reinvented each time someone
> implements reordering.
<hyatt> :droptarget
<hyatt> or something
<hyatt> we don't support a pseudo-class for the drop target but that's a great idea
<Hixie_> yeah, thinking about that too
<Hixie_> :drop-target, :drop-target(above), :drop-target(below) and having ondragover be able to say "not on me, but next to me maybe"
* We should let drop targets communicate back to drag sources if
they want to communicate. (e.g. expose Window, and thus
postMessage(), on the dataTransfer object on drop.)
We should let drag sources provide a set of options via a
context menu when the drop happens. (So that, e.g., the source
can know whether a capabilities URI that it is passing along is
supposed to be read-write access or read-only access to the
object being dragged.)
We should let potential drop targets see the types (but not the
contents!) of dragged data so they can establish if they care
or not. (dataTransfer.hasType())
Ack: Ben Laurie (@g)
-->
<p>This section defines an event-based drag-and-drop mechanism.</p>
<p>This specification does not define exactly what a
<em>drag-and-drop operation</em> actually is.</p>
<p>On a visual medium with a pointing device, a drag operation could
be the default action of a <code
title="event-mousedown">mousedown</code> event that is followed by a
series of <code title="event-mousemove">mousemove</code> events, and
the drop could be triggered by the mouse being released.</p>
<p>On media without a pointing device, the user would probably have
to explicitly indicate his intention to perform a drag-and-drop
operation, stating what he wishes to drag and what he wishes to
drop, respectively.</p>
<div class="impl">
<p>However it is implemented, drag-and-drop operations must have a
starting point (e.g. where the mouse was clicked, or the start of
<span>the selection</span> or element that was selected for the
drag), may have any number of intermediate steps (elements that the
mouse moves over during a drag, or elements that the user picks as
possible drop points as he cycles through possibilities), and must
either have an end point (the element above which the mouse button
was released, or the element that was finally selected), or be
canceled. The end point must be the last element selected as a
possible drop point before the drop occurs (so if the operation is
not canceled, there must be at least one element in the middle
step).</p>
</div>
<h4>Introduction</h4>
<p><i>This section is non-normative.</i></p>
<p>To make an element draggable is simple: give the element a <code
title="attr-draggable">draggable</code> attribute, and set an event
listener for <code title="event-dragstart">dragstart</code> that
stores the data being dragged.</p>
<p>The event handler typically needs to check that it's not a text
selection that is being dragged, and then needs to store data into
the <code>DataTransfer</code> object and set the allowed effects
(copy, move, link, or some combination).</p>
<p>For example:</p>
<pre><p>What fruits do you like?</p>
<ol ondragstart="dragStartHandler(event)">
<li draggable data-value="fruit-apple">Apples</li>
<li draggable data-value="fruit-orange">Oranges</li>
<li draggable data-value="fruit-pear">Pears</li>
</ol>
<script>
var internalDNDType = 'text/x-example'; // set this to something specific to your site
function dragStartHandler(event) {
if (event.target instanceof HTMLLIElement) {
// use the element's data-value="" attribute as the value to be moving:
event.dataTransfer.setData(internalDNDType, event.target.dataset.value);
event.effectAllowed = 'move'; // only allow moves
} else {
event.preventDefault(); // don't allow selection to be dragged
}
}
</script></pre>
<hr>
<p>To accept a drop, the drop target has to listen to at least three
events. First, the <code title="event-dragenter">dragenter</code>
event, which is used to determine whether or not the drop target is
to accept the drop. If the drop is to be accepted, then this event
has to be canceled. Second, the <code
title="event-dragover">dragover</code> event, which is used to
determine what feedback is to be shown to the user. If the event is
canceled, then the feedback (typically the cursor) is updated based
on the <code title="dom-DataTransfer-DropEffect">dropEffect</code>
attribute's value, as set by the event handler; otherwise, the
default behavior (typically to do nothing) is used instead. Finally,
the <code title="event-drop">drop</code> event, which allows the
actual drop to be performed. This event also needs to be canceled,
so that the <code
title="dom-DataTransfer-DropEffect">dropEffect</code> attribute's
value can be used by the source (otherwise it's reset).</p>
<p>For example:</p>
<pre><p>Drop your favourite fruits below:</p>
<ol class="dropzone"
ondragenter="dragEnterHandler(event)"
ondragover="dragOverHandler(event)"
ondrop="dropHandler(event)">
</ol>
<script>
var internalDNDType = 'text/x-example'; // set this to something specific to your site
function dragEnterHandler(event) {
// cancel the event if the drag contains data of our type
if (event.dataTransfer.types.contains(internalDNDType))
event.preventDefault();
}
function dragOverHandler(event) {
event.dataTransfer.dropEffect = 'move';
event.preventDefault();
}
function dropHandler(event) {
// drop the data
var li = document.createElement('li');
var data = event.dataTransfer.getData(internalDNDType);
if (data == 'fruit-apple') {
li.textContent = 'Apples';
} else if (data == 'fruit-orange') {
li.textContent = 'Oranges';
} else if (data == 'fruit-pear') {
li.textContent = 'Pears';
} else {
li.textContent = 'Unknown Fruit';
}
event.target.appendChild(li);
}
</script></pre>
<hr>
<p>To remove the original element (the one that was dragged) from
the display, the <code title="event-dragend">dragend</code> event
can be used.</p>
<p>For our example here, that means updating the original markup to
handle that event:</p>
<pre><p>What fruits do you like?</p>
<ol ondragstart="dragStartHandler(event)" ondragend="dragEndHandler(event)">
<em>...as before...</em>
</ol>
<script>
function dragStartHandler(event) {
// <em>...as before...</em>
}
function dragEndHandler(event) {
// remove the dragged element
event.target.parentNode.removeChild(event.target);
}
</script></pre>
<h4>The <code>DragEvent</code> and <code>DataTransfer</code> interfaces</h4>
<p>The drag-and-drop processing model involves several events. They
all use the <code>DragEvent</code> interface.</p>
<pre class="idl">interface <dfn>DragEvent</dfn> : <span>MouseEvent</span> {
readonly attribute <span>DataTransfer</span> <span title="dom-DragEvent-dataTransfer">dataTransfer</span>;
void <span title="dom-DragEvent-initDragEvent">initDragEvent</span>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in <span>AbstractView</span> viewArg, in long detailArg, in long screenXArg, in long screenYArg, in long clientXArg, in long clientYArg, in boolean ctrlKeyArg, in boolean altKeyArg, in boolean shiftKeyArg, in boolean metaKeyArg, in unsigned short buttonArg, in EventTarget relatedTargetArg, in <span>DataTransfer</span> dataTransferArg);
};</pre>
<dl class="domintro">
<dt><var title="">event</var> . <code title="dom-DragEvent-dataTransfer">dataTransfer</code></dt>
<dd>
<p>Returns the <code>DataTransfer</code> object for the event.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-DragEvent-initDragEvent"><code>initDragEvent()</code></dfn>
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. <a
href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p>The <dfn
title="dom-DragEvent-dataTransfer"><code>dataTransfer</code></dfn>
attribute of the <code>DragEvent</code> interface represents the
context information for the event.</p>
</div>
<pre class="idl">interface <dfn>DataTransfer</dfn> {
attribute DOMString <span title="dom-DataTransfer-dropEffect">dropEffect</span>;
attribute DOMString <span title="dom-DataTransfer-effectAllowed">effectAllowed</span>;
readonly attribute DOMStringList <span title="dom-DataTransfer-types">types</span>;
void <span title="dom-DataTransfer-clearData">clearData</span>(in optional DOMString format);
void <span title="dom-DataTransfer-setData">setData</span>(in DOMString format, in DOMString data);
DOMString <span title="dom-DataTransfer-getData">getData</span>(in DOMString format);
readonly attribute <span>FileList</span> <span title="dom-DataTransfer-files">files</span>;
void <span title="dom-DataTransfer-setDragImage">setDragImage</span>(in Element image, in long x, in long y);
void <span title="dom-DataTransfer-addElement">addElement</span>(in Element element);
};</pre>
<p><code>DataTransfer</code> objects can hold pieces of data, each
associated with a unique format. Formats are generally given by
<span title="MIME type">MIME types</span>, with some values
special-cased for legacy reasons. For the purposes of this API,
however, the format strings are opaque, <span>case-sensitive</span>,
strings, and the empty string is a valid format string.</p>
<dl class="domintro">
<dt><var title="">dataTransfer</var> . <code title="dom-DataTransfer-dropEffect">dropEffect</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the kind of operation that is currently selected. If
the kind of operation isn't one of those that is allowed by the
<code title="dom-DataTransfer-effectAllowed">effectAllowed</code>
attribute, then the operation will fail.</p>
<p>Can be set, to change the selected operation.</p>
<p>The possible values are <code title="">none</code>, <code
title="">copy</code>, <code title="">link</code>, and <code
title="">move</code>.</p>
</dd>
<dt><var title="">dataTransfer</var> . <code title="dom-DataTransfer-effectAllowed">effectAllowed</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns the kinds of operations that are to be allowed.</p>
<p>Can be set, to change the allowed operations.</p>
<p>The possible values are <code title="">none</code>, <code
title="">copy</code>, <code title="">copyLink</code>, <code
title="">copyMove</code>, <code title="">link</code>, <code
title="">linkMove</code>, <code title="">move</code>, <code
title="">all</code>, and <code title="">uninitialized</code>,</p>
</dd>
<dt><var title="">dataTransfer</var> . <code title="dom-DataTransfer-types">types</code></dt>
<dd>
<p>Returns a <code>DOMStringList</code> listing the formats that
were set in the <code title="event-dragstart">dragstart</code>
event. In addition, if any files are being dragged, then one of
the types will be the string "<code title="">Files</code>".</p>
</dd>
<dt><var title="">dataTransfer</var> . <code title="dom-DataTransfer-clearData">clearData</code>( [ <var title="">format</var> ] )</dt>
<dd>
<p>Removes the data of the specified formats. Removes all data if
the argument is omitted.</p>
</dd>
<dt><var title="">dataTransfer</var> . <code title="dom-DataTransfer-setData">setData</code>(<var title="">format</var>, <var title="">data</var>)</dt>
<dd>
<p>Adds the specified data.</p>
</dd>
<dt><var title="">data</var> = <var title="">dataTransfer</var> . <code title="dom-DataTransfer-getData">getData</code>(<var title="">format</var>)</dt>
<dd>
<p>Returns the specified data. If there is no such data, returns the empty string.</p>
</dd>
<dt><var title="">dataTransfer</var> . <code title="dom-DataTransfer-files">files</code></dt>
<dd>
<p>Returns a <code>FileList</code> of the files being dragged, if any.</p>
</dd>
<dt><var title="">dataTransfer</var> . <code title="dom-DataTransfer-setDragImage">setDragImage</code>(<var title="">element</var>, <var title="">x</var>, <var title="">y</var>)</dt>
<dd>
<p>Uses the given element to update the drag feedback, replacing any previously specified feedback.</p>
</dd>
<dt><var title="">dataTransfer</var> . <code title="dom-DataTransfer-addElement">addElement</code>(<var title="">element</var>)</dt>
<dd>
<p>Adds the given element to the list of elements used to render the drag feedback.</p>
</dd>
</dl>
<div class="impl">
<p>When a <code>DataTransfer</code> object is created, it must be
initialized as follows:</p>
<ul>
<li>The <code>DataTransfer</code> object must initially contain no
data, no elements, and have no associated image.</li>
<li>The <code>DataTransfer</code> object's <code
title="dom-DataTransfer-effectAllowed">effectAllowed</code>
attribute must be set to "<code
title="">uninitialized</code>".</li>
<li>The <code title="dom-DataTransfer-dropEffect">dropEffect</code>
attribute must be set to "<code title="">none</code>".</li>
</ul>
<p>The <dfn
title="dom-DataTransfer-dropEffect"><code>dropEffect</code></dfn>
attribute controls the drag-and-drop feedback that the user is given
during a drag-and-drop operation.</p>
<p>The attribute must ignore any attempts to set it to a value other
than <code title="">none</code>, <code title="">copy</code>, <code
title="">link</code>, and <code title="">move</code>. On getting,
the attribute must return the last of those four values that it was
set to.</p>
<p>The <dfn
title="dom-DataTransfer-effectAllowed"><code>effectAllowed</code></dfn>
attribute is used in the drag-and-drop processing model to
initialize the <code
title="dom-DataTransfer-dropEffect">dropEffect</code> attribute
during the <code title="event-dragenter">dragenter</code> and <code
title="event-dragover">dragover</code> events.</p>
<p>The attribute must ignore any attempts to set it to a value other
than <code title="">none</code>, <code title="">copy</code>, <code
title="">copyLink</code>, <code title="">copyMove</code>, <code
title="">link</code>, <code title="">linkMove</code>, <code
title="">move</code>, <code title="">all</code>, and <code
title="">uninitialized</code>. On getting, the attribute must return
the last of those values that it was set to.</p>
<p>The <dfn title="dom-DataTransfer-types"><code>types</code></dfn>
attribute must return a live <code>DOMStringList</code> that
contains the list of formats that were added to the
<code>DataTransfer</code> object in the corresponding <code
title="event-dragstart">dragstart</code> event. If any files were
included in the drag, then the <code>DOMStringList</code> object
must in addition include the string "<code
title="">Files</code>".</p>
<p class="note">If the <code
title="dom-DataTransfer-setData">setData()</code> method is invoked
with the string "<code title="">Files</code>", and some files were
included in the drag, then the string "<code title="">Files</code>"
will appear twice in the <code
title="dom-DataTransfer-types">types</code> attribute's list.</p>
<p>The <dfn
title="dom-DataTransfer-clearData"><code>clearData()</code></dfn>
method, when called with no arguments, must clear the
<code>DataTransfer</code> object of all data (for all formats).</p>
<p class="note">The <code
title="dom-DataTransfer-clearData">clearData()</code> method does
not affect whether any files were included in the drag, so the <code
title="dom-DataTransfer-types">types</code> attribute's list might
still not be empty after calling <code
title="dom-DataTransfer-clearData">clearData()</code> (it would
still contain the "<code title="">Files</code>" string if any files
were included in the drag).</p>
<p>When called with an argument, the <code
title="dom-DataTransfer-clearData">clearData(<var
title="">format</var>)</code> method must clear the
<code>DataTransfer</code> object of any data associated with the
given <var title="">format</var>. If <var title="">format</var> is
the value "<code title="">Text</code>", then it must be treated as
"<code title="">text/plain</code>". If the <var
title="">format</var> is "<code title="">URL</code>", then it must
be treated as "<code title="">text/uri-list</code>".</p>
<p>The <dfn title="dom-DataTransfer-setData"><code>setData(<var
title="">format</var>, <var title="">data</var>)</code></dfn> method
must add <var title="">data</var> to the data stored in the
<code>DataTransfer</code> object, labeled as being of the type <var
title="">format</var>. This must replace any previous data that had
been set for that format. If <var title="">format</var> is the value
"<code title="">Text</code>", then it must be treated as "<code
title="">text/plain</code>". If the <var title="">format</var> is
"<code title="">URL</code>", then it must be treated as "<code
title="">text/uri-list</code>".</p>
<p>The <dfn title="dom-DataTransfer-getData"><code>getData(<var
title="">format</var>)</code></dfn> method must return the data that
is associated with the type <var title="">format</var>, if any, and
must return the empty string otherwise. If <var
title="">format</var> is the value "<code title="">Text</code>",
then it must be treated as "<code title="">text/plain</code>". If
the <var title="">format</var> is "<code title="">URL</code>", then
the data associated with the "<code title="">text/uri-list</code>"
format must be parsed as appropriate for <code
title="">text/uri-list</code> data, and the first URL from the list
must be returned. If there is no data with that format, or if there
is but it has no URLs, then the method must return the empty
string. <a href="#refsRFC2483">[RFC2483]</a></p>
<p>The <dfn title="dom-DataTransfer-files"><code>files</code></dfn>
attribute must return the <code>FileList</code> object that contains
the files that are stored in the <code>DataTransfer</code>
object. There is one such object per <code>DataTransfer</code>
object.</p>
<p>The <dfn
title="dom-DataTransfer-setDragImage"><code>setDragImage(<var
title="">element</var>, <var title="">x</var>, <var
title="">y</var>)</code></dfn> method sets which element to use <a
href="#base-dnd-feedback">to generate the drag feedback</a>. The
<var title="">element</var> argument can be any
<code>Element</code>; if it is an <code>img</code> element, then the
user agent should use the element's image (at its intrinsic size) to
generate the feedback, otherwise the user agent should base the
feedback on the given element (but the exact mechanism for doing so
is not specified).</p>
<p>The <dfn
title="dom-DataTransfer-addElement"><code>addElement(<var
title="">element</var>)</code></dfn> method is an alternative way of
specifying how the user agent is to <a
href="#base-dnd-feedback">render the drag feedback</a>. It adds an
element to the <code>DataTransfer</code> object.</p>
<p class="note">The difference between <code
title="dom-DataTransfer-setDragImage">setDragImage()</code> and
<code title="dom-DataTransfer-addElement">addElement()</code> is
that the latter automatically generates the image based on the
current rendering of the elements added, whereas the former uses the
exact specified image.</p>
</div>
<h4 id="dndevents">Events fired during a drag-and-drop action</h4>
<p>The following events are involved in the drag-and-drop
model.</p>
<div class="impl">
<p>Whenever the processing model described
below causes one of these events to be fired, the event fired must
use the <code>DragEvent</code> interface defined above, must have
the bubbling and cancelable behaviors given in the table below, and
must have the context information set up as described after the
table, with the <code title="dom-UIEvent-view">view</code> attribute
set to the view with which the user interacted to trigger the
drag-and-drop event, the <code
title="dom-UIEvent-detail">detail</code> attribute set to zero, the
mouse and key attributes set according to the state of the input
devices as they would be for user interaction events, and the <code
title="">relatedTarget</code> attribute set to null.</p>
<p>If there is no relevant pointing device, the object must have its
<code title="">screenX</code>, <code title="">screenY</code>, <code
title="">clientX</code>, <code title="">clientY</code>, and <code
title="">button</code> attributes set to 0.</p>
<!-- interaction event spec point -->
</div>
<table>
<thead>
<tr>
<th> Event Name </th>
<th> Target </th>
<th> Bubbles? </th>
<th> Cancelable? </th>
<th> <code title="dom-DataTransfer-dataTransfer">dataTransfer</code> </th>
<th> <code title="dom-DataTransfer-effectAllowed">effectAllowed</code> </th>
<th> <code title="dom-DataTransfer-dropEffect">dropEffect</code> </th>
<th> Default Action </th>
</tr>
</thead>
<tbody>
<tr>
<td><dfn title="event-dragstart"><code>dragstart</code></dfn></td>
<td><span>Source node</span></td>
<td>✓ Bubbles</td>
<td>✓ Cancelable</td>
<td>Contains <span>source node</span> unless a selection is being dragged, in which case it is empty; <code title="dom-datatransfer-files">files</code> returns any files included in the drag operation</td>
<td><code title="">uninitialized</code></td>
<td><code title="">none</code></td>
<td>Initiate the drag-and-drop operation</td>
</tr>
<tr>
<td><dfn title="event-drag"><code>drag</code></dfn></td>
<td><span>Source node</span></td>
<td>✓ Bubbles</td>
<td>✓ Cancelable</td>
<td>Empty</td>
<td><a href="#effectAllowed-initialization">Same as last event</a></td>
<td><code title="">none</code></td>
<td>Continue the drag-and-drop operation</td>
</tr>
<tr>
<td><dfn title="event-dragenter"><code>dragenter</code></dfn></td>
<td><span>Immediate user selection</span> or <span>the body element</span></td>
<td>✓ Bubbles</td>
<td>✓ Cancelable</td>
<td>Empty</td>
<td><a href="#effectAllowed-initialization">Same as last event</a></td>
<td><a href="#dropEffect-initialization">Based on <code>effectAllowed</code> value</a></td>
<td>Reject <span>immediate user selection</span> as potential <span title="current target element">target element</span></td>
</tr>
<tr>
<td><dfn title="event-dragleave"><code>dragleave</code></dfn></td>
<td><span title="current target element">Previous target element</span></td>
<td>✓ Bubbles</td>
<td>—</td>
<td>Empty</td>
<td><a href="#effectAllowed-initialization">Same as last event</a></td>
<td><code title="">none</code></td>
<td>None</td>
</tr>
<tr>
<td><dfn title="event-dragover"><code>dragover</code></dfn></td>
<td><span>Current target element</span></td>
<td>✓ Bubbles</td>
<td>✓ Cancelable</td>
<td>Empty</td>
<td><a href="#effectAllowed-initialization">Same as last event</a></td>
<td><a href="#dropEffect-initialization">Based on <code>effectAllowed</code> value</a></td>
<td>Reset the <span>current drag operation</span> to "none"</td>
</tr>
<tr>
<td><dfn title="event-drop"><code>drop</code></dfn></td>
<td><span>Current target element</span></td>
<td>✓ Bubbles</td>
<td>✓ Cancelable</td>
<td><code title="dom-datatransfer-getdata">getData()</code> returns data set in <code title="dom-dragstart">dragstart</code> event; <code title="dom-datatransfer-files">files</code> returns any files included in the drag operation</td>
<td><a href="#effectAllowed-initialization">Same as last event</a></td>
<td><span>Current drag operation</span></td>
<td>Varies</td>
</tr>
<tr>
<td><dfn title="event-dragend"><code>dragend</code></dfn></td>
<td><span>Source node</span></td>
<td>✓ Bubbles</td>
<td>—</td>
<td>Empty</td>
<td><a href="#effectAllowed-initialization">Same as last event</a></td>
<td><span>Current drag operation</span></td>
<td>Varies</td>
</tr>
</tbody>
</table>
<div class="impl">
<p>The <code title="dom-DragEvent-dataTransfer">dataTransfer</code>
object's contents are empty except for <code
title="event-dragstart">dragstart</code> events and <code
title="event-drop">drop</code> events, for which the contents are
set as described in the processing model, below.</p>
<p id="effectAllowed-initialization">The <code
title="dom-DataTransfer-effectAllowed">effectAllowed</code>
attribute must be set to "<code title="">uninitialized</code>" for
<code title="event-dragstart">dragstart</code> events, and to
whatever value the field had after the last drag-and-drop event was
fired for all other events (only counting events fired by the user
agent for the purposes of the drag-and-drop model described
below).</p>
<p id="dropEffect-initialization">The <code
title="dom-DataTransfer-dropEffect">dropEffect</code> attribute must
be set to "<code title="">none</code>" for <code
title="event-dragstart">dragstart</code>, <code
title="event-drag">drag</code>, and <code
title="event-dragleave">dragleave</code> events (except when stated
otherwise in the algorithms given in the sections below), to the
value corresponding to the <span>current drag operation</span> for
<code title="event-drop">drop</code> and <code
title="event-dragend">dragend</code> events, and to a value based on
the <code
title="dom-DataTransfer-effectAllowed">effectAllowed</code>
attribute's value and to the drag-and-drop source, as given by the
following table, for the remaining events (<code
title="event-dragenter">dragenter</code> and <code
title="event-dragover">dragover</code>):</p>
<table>
<thead>
<tr>
<th><code title="dom-DataTransfer-effectAllowed">effectAllowed</code></th>
<th><code title="dom-DataTransfer-dropEffect">dropEffect</code></th>
</tr>
</thead>
<tr>
<td><code title="">none</code></td>
<td><code title="">none</code></td>
</tr>
<tr>
<td><code title="">copy</code>, <code title="">copyLink</code>, <code title="">copyMove</code>, <code title="">all</code></td>
<td><code title="">copy</code></td>
</tr>
<tr>
<td><code title="">link</code>, <code title="">linkMove</code></td>
<td><code title="">link</code></td>
</tr>
<tr>
<td><code title="">move</code></td>
<td><code title="">move</code></td>
</tr>
<tr>
<td><code title="">uninitialized</code> when what is being dragged is a selection from a text field</td>
<td><code title="">move</code></td>
</tr>
<tr>
<td><code title="">uninitialized</code> when what is being dragged is a selection</td>
<td><code title="">copy</code></td>
</tr>
<tr>
<td><code title="">uninitialized</code> when what is being dragged is an <code>a</code> element with an <code>href</code> attribute</td>
<td><code title="">link</code></td>
</tr>
<tr>
<td>Any other case</td>
<td><code title="">copy</code></td>
</tr>
</table>
</div>
<div class="impl">
<h4>Drag-and-drop processing model</h4>
<p>When the user attempts to begin a drag operation, the user agent
must first determine what is being dragged. If the drag operation
was invoked on a selection, then it is the selection that is being
dragged. Otherwise, it is the first element, going up the ancestor
chain, starting at the node that the user tried to drag, that has
the IDL attribute <code title="dom-draggable">draggable</code> set
to true. If there is no such element, then nothing is being dragged,
the drag-and-drop operation is never started, and the user agent
must not continue with this algorithm.</p>
<p class="note"><code>img</code> elements and <code>a</code>
elements with an <code title="attr-hyperlink-href">href</code>
attribute have their <code title="dom-draggable">draggable</code>
attribute set to true by default.</p>
<p>If the user agent determines that something can be dragged, a
<code title="event-dragstart">dragstart</code> event must then be
fired at the <span>source node</span>.</p>
<p>The <dfn>source node</dfn> depends on the kind of drag and how it
was initiated. If it is a selection that is being dragged, then the
<span>source node</span> is the text node that the user started the
drag on (typically the text node that the user originally
clicked). If the user did not specify a particular node, for example
if the user just told the user agent to begin a drag of "the
selection", then the <span>source node</span> is the first text node
containing a part of the selection. If it is not a selection that is
being dragged, then the <span>source node</span> is the element that
is being dragged.</p>
<p>Multiple events are fired on the <span>source node</span> during
the course of the drag-and-drop operation.</p>
<hr>
<p>The <dfn>list of dragged nodes</dfn> also depends on the kind of
drag. If it is a selection that is being dragged, then the
<span>list of dragged nodes</span> contains, in <span>tree
order</span>, every node that is partially or completely included in
the selection (including all their ancestors). Otherwise, the
<span>list of dragged nodes</span> contains only the <span>source
node</span>.</p>
<hr>
<p>If it is a selection that is being dragged, the <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> member of the
event must be created with no nodes. Otherwise, it must be created
containing just the <span>source node</span>. Script can use the
<code title="dom-DataTransfer-addElement">addElement()</code> method
to add further elements to the list of what is being dragged. (This
list is only used for rendering the drag feedback.)</p>
<p>The <code title="dom-DragEvent-dataTransfer">dataTransfer</code>
member of the event also has data added to it, as follows:</p>
<ul>
<li>
<p>If it is a selection that is being dragged, then the user agent
must add the text of the selection to the <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> member,
associated with the <code title="">text/plain</code> format.</p>
</li>
<li>
<p>If files are being dragged, then the user agent must add the
files to the <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> member's
<code title="dom-datatransfer-files">files</code> attribute's
<code>FileList</code> object. (Dragging files can only happen from
outside a <span>browsing context</span>, for example from a file
system manager application, and thus the <code
title="event-dragstart">dragstart</code> event is actually implied
in this case.)</p>
</li>
<li>
<p>The user agent must take the <span>list of dragged nodes</span>
and <span title="extracting JSON">extract the microdata from those
nodes into a JSON form</span>, and then must add the resulting
string to the <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> member,
associated with the <code
title="">application/microdata+json</code> format.</p>
</li>
<!-- v2: deal with multiple vCards -->
<!--
<li>
<p>The user agent must take the <span>list of dragged nodes</span>
and <span title="extracting a vCard">extract the vCard data from
those nodes</span>, and then must add the resulting string to the
<code title="dom-DragEvent-dataTransfer">dataTransfer</code>
member, associated with the <code
title="">text/directory;profile=vcard</code> format.</p>
</li>
<li>
<p>The user agent must take the <span>list of dragged nodes</span>
and <span title="extracting vEvent data">extract the vEvent data
from those nodes</span>, and then must add the resulting string to
the <code title="dom-DragEvent-dataTransfer">dataTransfer</code>
member, associated with the <code
title="">text/calendar;component=vevent</code> format.</p>
</li>
-->
<!-- v2: text/html -->
<li>
<p>The user agent must run the following steps:</p>
<ol>
<li><p>Let <var title="">urls</var> be an empty list of <span
title="absolute URL">absolute URLs</span>.</p></li>
<li>
<p>For each <var title="">node</var> in <var
title="">nodes</var>:</p>
<dl>
<dt>If the node is an <code>a</code> element with an <code
title="attr-hyperlink-href">href</code></dt>
<dd>Add to <var title="">urls</var> the result of <span
title="resolve a url">resolving</span> the element's <code
title="attr-hyperlink-href">href</code> content attribute relative to
the element.</dd>
<dt>If the node is an <code>img</code> element with an <code
title="attr-img-src">src</code></dt>
<dd>Add to <var title="">urls</var> the result of <span
title="resolve a url">resolving</span> the element's <code
title="attr-img-src">src</code> content attribute relative to the
element.</dd>
<!-- v2: more -->
</dl>
</li>
<li><p>If <var title="">urls</var> is still empty, abort these
steps.</p></li>
<li><p>Let <var title="">url string</var> be the result of
concatenating the strings in <var title="">urls</var>, in the
order they were added, separated by a U+000D CARRIAGE RETURN
U+000A LINE FEED character pair (CRLF).</p></li>
<li><p>Add <var title="">url string</var> to the <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> member,
associated with the <code title="">text/uri-list</code>
format.</p></li>
</ol>
</li>
</ul>
<hr>
<p>If the event is canceled, then the drag-and-drop operation must
not occur; the user agent must not continue with this algorithm.</p>
<p>If it is not canceled, then the drag-and-drop operation must be
initiated.</p>
<p class="note">Since events with no event listeners registered are,
almost by definition, never canceled, drag-and-drop is always
available to the user if the author does not specifically prevent
it.</p>
<p id="base-dnd-feedback">The drag-and-drop feedback must be
generated from the first of the following sources that is
available:</p>
<ol>
<li>The element specified in the last call to the <code
title="dom-DataTransfer-setDragImage">setDragImage()</code> method
of the <code title="dom-DragEvent-dataTransfer">dataTransfer</code>
object of the <code title="event-dragstart">dragstart</code> event,
if the method was called. In visual media, if this is used, the
<var title="">x</var> and <var title="">y</var> arguments that were
passed to that method should be used as hints for where to put the
cursor relative to the resulting image. The values are expressed as
distances in CSS pixels from the left side and from the top side of
the image respectively. <a href="#refsCSS">[CSS]</a></li>
<li>The elements that were added to the <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> object, both
before the event was fired, and during the handling of the event
using the <code
title="dom-DataTransfer-addElement">addElement()</code>
method, if any such elements were indeed added.</li>
<li>The selection that the user is dragging.</li>
</ol>
<p>The user agent must take a note of <span
title="dom-DataTransfer-setData">the data that was placed</span> in
the <code title="dom-DragEvent-dataTransfer">dataTransfer</code>
object. This data will be made available again when the <code
title="event-drop">drop</code> event is fired.</p>
<p>From this point until the end of the drag-and-drop operation,
device input events (e.g. mouse and keyboard events) must be
suppressed. In addition, the user agent must track all DOM changes
made during the drag-and-drop operation, and add them to its <a
href="#undo">undo history</a> as one atomic operation once the
drag-and-drop operation has ended.</p>
<p>During the drag operation, the element directly indicated by the
user as the drop target is called the <dfn>immediate user
selection</dfn>. (Only elements can be selected by the user; other
nodes must not be made available as drop targets.)
However, the <span>immediate user selection</span> is not
necessarily the <dfn>current target element</dfn>, which is the
element currently selected for the drop part of the drag-and-drop
operation.
The <span>immediate user selection</span> changes as the user
selects different elements (either by pointing at them with a
pointing device, or by selecting them in some other way). The
<span>current target element</span> changes when the <span>immediate
user selection</span> changes, based on the results of event
listeners in the document, as described below.</p>
<p>Both the <span>current target element</span> and the
<span>immediate user selection</span> can be null, which means no
target element is selected. They can also both be elements in other
(DOM-based) documents, or other (non-Web) programs altogether. (For
example, a user could drag text to a word-processor.) The
<span>current target element</span> is initially null.</p>
<p>In addition, there is also a <dfn>current drag operation</dfn>,
which can take on the values "none", "copy", "link", and "move".
Initially, it has the value "none". It is updated by the user agent
as described in the steps below.</p>
<p>User agents must, every 350ms (±200ms), perform the
following steps in sequence. (If the user agent is still performing
the previous iteration of the sequence when the next iteration
becomes due, the user agent must not execute the overdue iteration,
effectively "skipping missed frames" of the drag-and-drop
operation.)</p>
<ol>
<li>
<p>First, the user agent must fire a <code
title="event-drag">drag</code> event at the <span>source
node</span>. If this event is canceled, the user agent must set
the <span>current drag operation</span> to none (no drag
operation).</p>
</li>
<li>
<p>Next, if the <code title="event-drag">drag</code> event was not
canceled and the user has not ended the drag-and-drop operation,
the user agent must check the state of the drag-and-drop
operation, as follows:</p>
<ol>
<li>
<p>First, if the user is indicating a different <span>immediate
user selection</span> than during the last iteration (or if this
is the first iteration), and if this <span>immediate user
selection</span> is not the same as the <span>current target
element</span>, then the <span>current target element</span> must
be updated, as follows:</p>
<dl class="switch">
<dt>If the new <span>immediate user selection</span> is null, or
is in a non-DOM document or application</dt>
<dd><p>The user agent must set the <span>current target
element</span> to the same value.</p></dd>
<dt>Otherwise</dt>
<dd>
<p>The user agent must fire a <code
title="event-dragenter">dragenter</code> event at the
<span>immediate user selection</span>.</p>
<p>If the event is canceled, then the <span>current target
element</span> must be set to the <span>immediate user
selection</span>.</p>
<p>Otherwise, the user agent must act as follows:</p>
<dl class="switch">
<dt>If the <span>current target element</span> is a text
field (e.g. <code>textarea</code>, or an <code>input</code>
element whose <code title="attr-input-type">type</code>
attribute is in the <span
title="attr-input-type-text">Text</span> state) or an
<span>editable</span> element</dt>
<dd><p>The <span>current target element</span> must be set to
the <span>immediate user selection</span> anyway.</p></dd>
<dt>If the <span>current target element</span> is
<span>the body element</span></dt>
<dd><p>The <span>current target element</span> is left
unchanged.</p></dd>
<dt>Otherwise</dt>
<dd><p>The user agent must fire a <code
title="event-dragenter">dragenter</code> event at <span>the
body element</span>, and the <span>current target
element</span> must be set to <span>the body element</span>,
regardless of whether that event was canceled or not. (If
<span>the body element</span> is null, then the <span>current
target element</span> would be set to null too in this case,
it wouldn't be set to the <code>Document</code>
object.)</p></dd>
</dl>
</dd>
</dl>
</li>
<li>
<p>If the previous step caused the <span>current target
element</span> to change, and if the previous target element was
not null or a part of a non-DOM document, the user agent must fire
a <code title="event-dragleave">dragleave</code> event at the
previous target element.</p>
</li>
<li>
<p>If the <span>current target element</span> is a DOM element,
the user agent must fire a <code
title="event-dragover">dragover</code> event at this <span>current
target element</span>.</p>
<p>If the <code title="event-dragover">dragover</code> event is
not canceled, the user agent must act as follows:</p>
<dl class="switch">
<dt>If the <span>current target element</span> is a text field
(e.g. <code>textarea</code>, or an <code>input</code> element
whose <code title="attr-input-type">type</code> attribute is in
the <span title="attr-input-type-text">Text</span> state) or an
<span>editable</span> element</dt>
<dd><p>The user agent must set the <span>current drag
operation</span> to either "copy" or "move", as appropriate
given the platform conventions.</p></dd>
<dt>Otherwise</dt>
<dd><p>The user agent must reset the <span>current drag
operation</span> to "none".</p></dd>
</dl>
<p>Otherwise (if the <code
title="event-dragover">dragover</code> event <em>is</em>
canceled), the <span>current drag operation</span> must be set
based on the values the <code
title="dom-DataTransfer-effectAllowed">effectAllowed</code> and
<code title="dom-DataTransfer-dropEffect">dropEffect</code>
attributes of the <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> object
had after the event was handled, as per the following table:</p>
<table>
<thead>
<tr>
<th><code title="dom-DataTransfer-effectAllowed">effectAllowed</code></th>
<th><code title="dom-DataTransfer-dropEffect">dropEffect</code></th>
<th>Drag operation</th>
</tr>
</thead>
<tr>
<td><code title="">uninitialized</code>, <code title="">copy</code>, <code title="">copyLink</code>, <code title="">copyMove</code>, or <code title="">all</code></td>
<td><code title="">copy</code></td>
<td>"copy"</td>
</tr>
<tr>
<td><code title="">uninitialized</code>, <code title="">link</code>, <code title="">copyLink</code>, <code title="">linkMove</code>, or <code title="">all</code></td>
<td><code title="">link</code></td>
<td>"link"</td>
</tr>
<tr>
<td><code title="">uninitialized</code>, <code title="">move</code>, <code title="">copyMove</code>, <code title="">linkMove</code>, or <code title="">all</code></td>
<td><code title="">move</code></td>
<td>"move"</td>
</tr>
<tr>
<td colspan="2">Any other case</td>
<td>"none"</td>
</tr>
</table>
<p>Then, regardless of whether the <code
title="event-dragover">dragover</code> event was canceled or
not, the drag feedback (e.g. the mouse cursor) must be updated
to match the <span>current drag operation</span>, as
follows:</p>
<table>
<thead>
<tr>
<th>Drag operation</th>
<th>Feedback</th>
</tr>
</thead>
<tr>
<td>"copy"</td>
<td>Data will be copied if dropped here.</td>
</tr>
<tr>
<td>"link"</td>
<td>Data will be linked if dropped here.</td>
</tr>
<tr>
<td>"move"</td>
<td>Data will be moved if dropped here.</td>
</tr>
<tr>
<td>"none"</td>
<td>No operation allowed, dropping here will cancel the drag-and-drop operation.</td>
</tr>
</table>
</li>
<li>
<p>Otherwise, if the <span>current target element</span> is not a
DOM element, the user agent must use platform-specific mechanisms
to determine what drag operation is being performed (none, copy,
link, or move). This sets the <em>current drag operation</em>.</p>
</li>
</ol>
</li>
<li>
<p>Otherwise, if the user ended the drag-and-drop operation (e.g.
by releasing the mouse button in a mouse-driven drag-and-drop
interface), or if the <code title="event-drag">drag</code> event
was canceled, then this will be the last iteration. The user agent
must execute the following steps, then stop looping.</p>
<ol>
<li>
<p>If the <span>current drag operation</span> is none (no drag
operation), or, if the user ended the drag-and-drop operation by
canceling it (e.g. by hitting the <kbd>Escape</kbd> key), or if
the <span>current target element</span> is null, then the drag
operation failed. If the <span>current target element</span> is
a DOM element, the user agent must fire a <code
title="event-dragleave">dragleave</code> event at it; otherwise,
if it is not null, it must use platform-specific conventions for
drag cancellation.</p>
</li>
<li>
<p>Otherwise, the drag operation was as success. If the
<span>current target element</span> is a DOM element, the user
agent must fire a <code title="event-drop">drop</code> event at
it; otherwise, it must use platform-specific conventions for
indicating a drop.</p>
<p>When the target is a DOM element, the <code
title="dom-DataTransfer-dropEffect">dropEffect</code> attribute
of the event's <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> object
must be given the value representing the <span>current drag
operation</span> (<code title="">copy</code>, <code
title="">link</code>, or <code title="">move</code>), and the
object must be set up so that the <code
title="dom-DataTransfer-getData">getData()</code> method will
return the data that was added during the <code
title="event-dragstart">dragstart</code> event, and the <code
title="dom-datatransfer-files">files</code> attribute will
return a <code>FileList</code> object with any files that were
dragged.</p>
<p>If the event is canceled, the <span>current drag
operation</span> must be set to the value of the <code
title="dom-DataTransfer-dropEffect">dropEffect</code> attribute
of the event's <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> object as
it stood after the event was handled.</p>
<p>Otherwise, the event is not canceled, and the user agent must
perform the event's default action, which depends on the exact
target as follows:</p>
<dl class="switch">
<dt>If the <span>current target element</span> is a text field
(e.g. <code>textarea</code>, or an <code>input</code> element
whose <code title="attr-input-type">type</code> attribute is in
the <span title="attr-input-type-text">Text</span> state) or an
<span>editable</span> element</dt>
<dd>The user agent must insert the data associated with the
<code>text/plain</code> format, if any, into the text field or
<span>editable</span> element in a manner consistent with
platform-specific conventions (e.g. inserting it at the current
mouse cursor position, or inserting it at the end of the
field).</dd>
<dt>Otherwise</dt>
<dd>Reset the <span>current drag operation</span> to
"none".</dd>
</dl>
</li>
<li>
<p>Finally, the user agent must fire a <code
title="event-dragend">dragend</code> event at the <span>source
node</span>, with the <code
title="dom-DataTransfer-dropEffect">dropEffect</code> attribute
of the event's <code
title="dom-DragEvent-dataTransfer">dataTransfer</code> object
being set to the value corresponding to the <span>current drag
operation</span>.</p>
<p class="note">The <span>current drag operation</span> can
change during the processing of the <code
title="event-drop">drop</code> event, if one was fired.</p>
<p>The event is not cancelable. After the event has been
handled, the user agent must act as follows:</p>
<dl class="switch">
<dt>If the <span>current target element</span> is a text field
(e.g. <code>textarea</code>, or an <code>input</code> element
whose <code title="attr-input-type">type</code> attribute is in
the <span title="attr-input-type-text">Text</span> state), and
a <code title="event-drop">drop</code> event was fired in the
previous step, and the <span>current drag operation</span> is
"move", and the source of the drag-and-drop operation is a
selection in the DOM</dt>
<dd>The user agent should delete the range representing the
dragged selection from the DOM.</dd>
<dt>If the <span>current target element</span> is a text field
(e.g. <code>textarea</code>, or an <code>input</code> element
whose <code title="attr-input-type">type</code> attribute is in
the <span title="attr-input-type-text">Text</span> state), and
a <code title="event-drop">drop</code> event was fired in the
previous step, and the <span>current drag operation</span> is
"move", and the source of the drag-and-drop operation is a
selection in a text field</dt>
<dd>The user agent should delete the dragged selection from the
relevant text field.</dd>
<dt>Otherwise</dt>
<dd>The event has no default action.</dd>
</dl>
</li>
</ol>
</li>
</ol>
</div>
<div class="impl">
<h5>When the drag-and-drop operation starts or ends in another
document</h5>
<p>The model described above is independent of which
<code>Document</code> object the nodes involved are from; the events
must be fired as described above and the rest of the processing
model must be followed as described above, irrespective of how many
documents are involved in the operation.</p>
<!-- should we mention that you shouldn't include the view from the
source in the events to the target, or is that obvious enough from
the requirements in the event section above? -->
</div>
<div class="impl">
<h5>When the drag-and-drop operation starts or ends in another
application</h5>
<p>If the drag is initiated in another application, the <span>source
node</span> is not a DOM node, and the user agent must use
platform-specific conventions instead when the requirements above
involve the source node. User agents in this situation must act as
if the dragged data had been added to the <code>DataTransfer</code>
object when the drag started, even though no <code
title="event-dragstart">dragstart</code> event was actually fired;
user agents must similarly use platform-specific conventions when
deciding on what drag feedback to use.</p>
<p>If a drag is started in a document but ends in another
application, then the user agent must instead replace the parts of
the processing model relating to handling the <em>target</em>
according to platform-specific conventions.</p>
<p>In any case, scripts running in the context of the document must
not be able to distinguish the case of a drag-and-drop operation
being started or ended in another application from the case of a
drag-and-drop operation being started or ended in another document
from another domain.</p>
</div>
<h4>The <dfn title="attr-draggable"><code>draggable</code></dfn> attribute</h4>
<p>All <span>HTML elements</span> may have the <code
title="attr-draggable">draggable</code> content attribute set. The
<code title="attr-draggable">draggable</code> attribute is an
<span>enumerated attribute</span>. It has three states. The first
state is <i>true</i> and it has the keyword <code
title="">true</code>. The second state is <i>false</i> and it has
the keyword <code title="">false</code>. The third state is
<i>auto</i>; it has no keywords but it is the <i>missing value
default</i>.</p>
<p>The <i>true</i> state means the element is draggable; the
<i>false</i> state means that it is not. The <i>auto</i> state
uses the default behavior of the user agent.</p>
<dl class="domintro">
<dt><var title="">element</var> . <code title="dom-draggable">draggable</code> [ = <var title="">value</var> ]</dt>
<dd>
<p>Returns true if the element is draggable; otherwise, returns
false.</p>
<p>Can be set, to override the default and set the <code
title="attr-draggable">draggable</code> content attribute.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-draggable"><code>draggable</code></dfn> IDL
attribute, whose value depends on the content attribute's in the way
described below, controls whether or not the element is
draggable. Generally, only text selections are draggable, but
elements whose <code title="dom-draggable">draggable</code> IDL
attribute is true become draggable as well.</p>
<p>If an element's <code title="attr-draggable">draggable</code>
content attribute has the state <i>true</i>, the <code
title="dom-draggable">draggable</code> IDL attribute must return
true.</p>
<p>Otherwise, if the element's <code
title="attr-draggable">draggable</code> content attribute has the
state <i>false</i>, the <code
title="dom-draggable">draggable</code> IDL attribute must return
false.</p>
<p>Otherwise, the element's <code
title="attr-draggable">draggable</code> content attribute has the
state <i>auto</i>. If the element is an <code>img</code> element,
or, if the element is an <code>a</code> element with an <code
title="attr-hyperlink-href">href</code> content attribute, the <code
title="dom-draggable">draggable</code> IDL attribute must return
true.</p>
<p>Otherwise, the <code title="dom-draggable">draggable</code> DOM
must return false.</p>
<p>If the <code title="dom-draggable">draggable</code> IDL attribute
is set to the value false, the <code
title="attr-draggable">draggable</code> content attribute must be
set to the literal value <code title="">false</code>. If the <code
title="dom-draggable">draggable</code> IDL attribute is set to the
value true, the <code title="attr-draggable">draggable</code>
content attribute must be set to the literal value <code
title="">true</code>.</p>
</div>
<h4>Copy and paste</h4>
<p>Copy-and-paste is a form of drag-and-drop: the "copy" part is
equivalent to dragging content to another application (the
"clipboard"), and the "paste" part is equivalent to dragging content
<em>from</em> another application.</p>
<p>Select-and-paste (a model used by mouse operations in the X
Window System) is equivalent to a drag-and-drop operation where the
source is the selection.</p>
<div class="impl">
<h5>Copy to clipboard</h5>
<p>When the user invokes a copy operation, the user agent must act
as if the user had invoked a drag on the current selection. If the
drag-and-drop operation initiates, then the user agent must act as
if the user had indicated (as the <span>immediate user
selection</span>) a hypothetical application representing the
clipboard. Then, the user agent must act as if the user had ended
the drag-and-drop operation without canceling it. If the
drag-and-drop operation didn't get canceled, the user agent should
then follow the relevant platform-specific conventions for copy
operations (e.g. updating the clipboard).</p>
<p>The events involved in this process are the <code
title="event-drag">drag</code>, <code
title="event-dragend">dragend</code>, and <code
title="event-drop">drop</code> events.</p>
<h5>Cut to clipboard</h5>
<p>When the user invokes a cut operation, the user agent must act as
if the user had invoked a copy operation (see the previous section),
followed, if the copy was completed successfully, by <a
href="#contenteditable-delete">a selection delete operation</a>.</p>
<p>The events involved in this process are the <code
title="event-drag">drag</code>, <code
title="event-dragend">dragend</code>, and <code
title="event-drop">drop</code> events.</p>
<h5>Paste from clipboard</h5>
<p>When the user invokes a clipboard paste operation, the user agent
must act as if the user had invoked a drag on a hypothetical
application representing the clipboard, setting the data associated
with the drag as the content on the clipboard (in whatever formats
are available).</p>
<p>Then, the user agent must act as if the user had indicated (as
the <span>immediate user selection</span>) the element with the
keyboard focus, and then ended the drag-and-drop operation without
canceling it.</p>
<p>The events involved in this process are the <code
title="event-dragenter">dragenter</code>, <code
title="event-dragover">dragover</code>, <code
title="event-dragleave">dragleave</code>, and <code
title="event-drop">drop</code> events.</p>
<h5>Paste from selection</h5>
<p>When the user invokes a selection paste operation, the user agent
must act as if the user had invoked a drag on the current selection,
then indicated (as the <span>immediate user selection</span>) the
element with the keyboard focus, and then ended the drag-and-drop
operation without canceling it.</p>
<p>All the drag-and-drop events can be involved in this process.</p>
</div>
<div class="impl">
<h4>Security risks in the drag-and-drop model</h4>
<p>User agents must not make the data added to the
<code>DataTransfer</code> object during the <code
title="event-dragstart">dragstart</code> event available to scripts
until the <code title="event-drop">drop</code> event, because
otherwise, if a user were to drag sensitive information from one
document to a second document, crossing a hostile third document in
the process, the hostile document could intercept the data.</p>
<p>For the same reason, user agents must consider a drop to be
successful only if the user specifically ended the drag operation
— if any scripts end the drag operation, it must be considered
unsuccessful (canceled) and the <code title="event-drop">drop</code>
event must not be fired.</p>
<p>User agents should take care to not start drag-and-drop
operations in response to script actions. For example, in a
mouse-and-window environment, if a script moves a window while the
user has his mouse button depressed, the UA would not consider that
to start a drag. This is important because otherwise UAs could cause
data to be dragged from sensitive sources and dropped into hostile
documents without the user's consent.</p>
</div>
<h3 id="undo"><dfn>Undo history</dfn></h3>
<div class="impl">
<h4>Definitions</h4>
<p>The user agent must associate an <dfn>undo transaction
history</dfn> with each <code>HTMLDocument</code> object.</p>
<p>The <span>undo transaction history</span> is a list of
entries. The entries are of two types: <span>DOM changes</span> and
<span title="undo object">undo objects</span>.</p>
<p>Each <dfn>DOM changes</dfn> entry in the <span>undo transaction
history</span> consists of batches of one or more of the
following:</p>
<ul>
<li>Changes to the content attributes of an <code>Element</code>
node.</li>
<li>Changes to the DOM hierarchy of nodes that are descendants of
the <code>HTMLDocument</code> object (<code>parentNode</code>,
<code>childNodes</code>).</li>
<li>Changes to internal state, such as a form control's <span
title="concept-fe-value">value</span> or <span
title="concept-input-checked-dirty-flag">dirty checkedness
flag</span>.</li>
</ul>
<p><dfn>Undo object</dfn> entries consist of objects representing
state that scripts running in the document are managing. For
example, a Web mail application could use an <span>undo
object</span> to keep track of the fact that a user has moved an
e-mail to a particular folder, so that the user can undo the
action and have the e-mail return to its former location.</p>
<p>Broadly speaking, <span>DOM changes</span> entries are handled by
the UA in response to user edits of form controls and <span
title="editing host">editing hosts</span> on the page, and
<span>undo object</span> entries are handled by script in response
to higher-level user actions (such as interactions with server-side
state, or in the implementation of a drawing tool).</p>
</div>
<h4>The <code>UndoManager</code> interface</h4>
<p>To manage <span>undo object</span> entries in the <span>undo
transaction history</span>, the <code>UndoManager</code>
interface can be used:</p>
<pre class="idl">interface <dfn>UndoManager</dfn> {
readonly attribute unsigned long <span title="dom-UndoManager-length">length</span>;
getter any <span title="dom-UndoManager-item">item</span>(in unsigned long index);
readonly attribute unsigned long <span title="dom-UndoManager-position">position</span>;
unsigned long <span title="dom-UndoManager-add">add</span>(in any data, in DOMString title);
void <span title="dom-UndoManager-remove">remove</span>(in unsigned long index);
void <span title="dom-UndoManager-clearUndo">clearUndo</span>();
void <span title="dom-UndoManager-clearRedo">clearRedo</span>();
};</pre>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-undoManager">undoManager</code></dt>
<dd>
<p>Returns the <code>UndoManager</code> object.</p>
</dd>
<dt><var title="">undoManager</var> . <code title="dom-UndoManager-length">length</code></dt>
<dd>
<p>Returns the number of entries in the undo history.</p>
</dd>
<dt><var title="">data</var> = <var title="">undoManager</var> . <code title="dom-UndoManager-item">item</code>(<var title="">index</var>)</dt>
<dt><var title="">undoManager</var>[<var title="">index</var>]</dt>
<dd>
<p>Returns the entry with index <var title="">index</var> in the undo history.</p>
<p>Returns null if <var title="">index</var> is out of range.</p>
</dd>
<dt><var title="">undoManager</var> . <code title="dom-UndoManager-position">position</code></dt>
<dd>
<p>Returns the number of the current entry in the undo history. (Entries at and past this point are <em>redo</em> entries.)</p>
</dd>
<dt><var title="">undoManager</var> . <code title="dom-UndoManager-add">add</code>(<var title="">data</var>, <var title="">title</var>)</dt>
<dd>
<p>Adds the specified entry to the undo history.</p>
</dd>
<dt><var title="">undoManager</var> . <code title="dom-UndoManager-remove">remove</code>(<var title="">index</var>)</dt>
<dd>
<p>Removes the specified entry to the undo history.</p>
<p>Throws an <code>INDEX_SIZE_ERR</code> exception if the given index is out of range.</p>
</dd>
<dt><var title="">undoManager</var> . <code title="dom-UndoManager-clearUndo">clearUndo</code>()</dt>
<dd>
<p>Removes all entries before the current position in the undo history.</p>
</dd>
<dt><var title="">undoManager</var> . <code title="dom-UndoManager-clearRedo">clearRedo</code>()</dt>
<dd>
<p>Removes all entries at and after the current position in the undo history.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn title="dom-undoManager"><code>undoManager</code></dfn>
attribute of the <code>Window</code> interface must return the
object implementing the <code>UndoManager</code> interface for that
<code>Window</code> object's associated
<code>HTMLDocument</code> object.</p>
<p><code>UndoManager</code> objects represent their document's
<span>undo transaction history</span>. Only <span>undo object</span>
entries are visible with this API, but this does not mean that
<span>DOM changes</span> entries are absent from the <span>undo
transaction history</span>.</p>
<p>The <dfn title="dom-UndoManager-length"><code>length</code></dfn>
attribute must return the number of <span>undo object</span> entries
in the <span>undo transaction history</span>. This is the <var
title="dom-UndoManager-length">length</var>.</p>
<p>The object's <span>indices of the supported indexed
properties</span> are the numbers in the range zero to <span title=""><var
title="dom-UndoManager-length">length</var>-1</span>, unless the
<var title="dom-UndoManager-length">length</var> is zero, in which
case there are no <span>supported indexed properties</span>.</p>
<p>The <dfn title="dom-UndoManager-item"><code>item(<var
title="">n</var>)</code></dfn> method must return the <var
title="">n</var>th <span>undo object</span> entry in the <span>undo
transaction history</span>, if there is one, or null otherwise.</p>
<p>The <span>undo transaction history</span> has a <dfn title="undo
position">current position</dfn>. This is the position between two
entries in the <span>undo transaction history</span>'s list where
the previous entry represents what needs to happen if the user
invokes the "undo" command (the "undo" side, lower numbers), and the
next entry represents what needs to happen if the user invokes the
"redo" command (the "redo" side, higher numbers).</p>
<p>The <dfn
title="dom-UndoManager-position"><code>position</code></dfn>
attribute must return the index of the <span>undo object</span>
entry nearest to the <span>undo position</span>, on the "redo"
side. If there are no <span>undo object</span> entries on the "redo"
side, then the attribute must return the same as the <code
title="dom-UndoManager-length">length</code> attribute. If there are
no <span>undo object</span> entries on the "undo" side of the
<span>undo position</span>, the <code
title="dom-UndoManager-position">position</code> attribute returns
zero.</p>
<p class="note">Since the <span>undo transaction history</span>
contains both <span>undo object</span> entries and <span>DOM
changes</span> entries, but the <code
title="dom-UndoManager-position">position</code> attribute only
returns indices relative to <span>undo object</span> entries, it is
possible for several "undo" or "redo" actions to be performed
without the value of the <code
title="dom-UndoManager-position">position</code> attribute
changing.</p>
<p>The <dfn title="dom-UndoManager-add"><code>add(<var title="">data</var>,
<var title="">title</var>)</code></dfn> method's behavior depends on the
current state. Normally, it must insert the <var title="">data</var> object
passed as an argument into the <span>undo transaction history</span>
immediately before the <span>undo position</span>, optionally
remembering the given <var title="">title</var> to use in the UI. If the
method is called <span title="do-undo">during an undo
operation</span>, however, the object must instead be added
immediately <em>after</em> the <span>undo position</span>.</p>
<p>If the method is called and there is neither <span
title="do-undo">an undo operation in progress</span> nor <span
title="do-redo">a redo operation in progress</span> then any entries
in the <span>undo transaction history</span> after the <span>undo
position</span> must be removed (as if <code
title="dom-UndoManager-clearRedo">clearRedo()</code> had been
called).</p>
<p>The <dfn title="dom-UndoManager-remove"><code>remove(<var
title="">index</var>)</code></dfn> method must remove the <span>undo
object</span> entry with the specified <var title="">index</var>. If
the index is less than zero or greater than or equal to <code
title="dom-UndoManager-length">length</code> then the method must
raise an <code>INDEX_SIZE_ERR</code> exception. <span>DOM
changes</span> entries are unaffected by this method.</p>
<p>The <dfn
title="dom-UndoManager-clearUndo"><code>clearUndo()</code></dfn>
method must remove all entries in the <span>undo transaction
history</span> before the <span>undo position</span>, be they
<span>DOM changes</span> entries or <span>undo object</span>
entries.</p>
<p>The <dfn
title="dom-UndoManager-clearRedo"><code>clearRedo()</code></dfn>
method must remove all entries in the <span>undo transaction
history</span> after the <span>undo position</span>, be they
<span>DOM changes</span> entries or <span>undo object</span>
entries.</p>
</div>
<div class="impl">
<h4><dfn title="do-undo">Undo: moving back in the undo transaction history</dfn></h4>
<p>When the user invokes an undo operation, or when the <code
title="dom-document-execCommand">execCommand()</code> method is
called with the <code title="command-undo">undo</code> command, the
user agent must perform an undo operation.</p>
<p>If the <span>undo position</span> is at the start of the
<span>undo transaction history</span>, then the user agent must do
nothing.</p>
<p>If the entry immediately before the <span>undo position</span> is
a <span>DOM changes</span> entry, then the user agent must remove
that <span>DOM changes</span> entry, reverse the DOM changes that
were listed in that entry, and, if the changes were reversed with no
problems, add a new <span>DOM changes</span> entry (consisting of
the opposite of those DOM changes) to the <span>undo transaction
history</span> on the other side of the <span>undo
position</span>.</p>
<p>If the DOM changes cannot be undone (e.g. because the DOM state
is no longer consistent with the changes represented in the entry),
then the user agent must simply remove the <span>DOM changes</span>
entry, without doing anything else.</p>
<p>If the entry immediately before the <span>undo position</span> is
an <span>undo object</span> entry, then the user agent must first
remove that <span>undo object</span> entry from the <span>undo
transaction history</span>, and then must fire an <code
title="event-undo">undo</code> event at the <code>Window</code>
object, using the <span>undo object</span> entry's associated undo
object as the event's data.</p>
<p>Any calls to <code title="dom-undoManager-add">add()</code> while
the event is being handled will be used to populate the redo
history, and will then be used if the user invokes the "redo"
command to undo his undo.</p>
<h4><dfn title="do-redo">Redo: moving forward in the undo transaction history</dfn></h4>
<p>When the user invokes a redo operation, or when the <code
title="dom-document-execCommand">execCommand()</code> method is
called with the <code title="command-redo">redo</code> command, the
user agent must perform a redo operation.</p>
<p>This is mostly the opposite of an <span title="do-undo">undo
operation</span>, but the full definition is included here for
completeness.</p>
<p>If the <span>undo position</span> is at the end of the <span>undo
transaction history</span>, then the user agent must do nothing.</p>
<p>If the entry immediately after the <span>undo position</span> is
a <span>DOM changes</span> entry, then the user agent must remove
that <span>DOM changes</span> entry, reverse the DOM changes that
were listed in that entry, and, if the changes were reversed with no
problems, add a new <span>DOM changes</span> entry (consisting of
the opposite of those DOM changes) to the <span>undo transaction
history</span> on the other side of the <span>undo
position</span>.</p>
<p>If the DOM changes cannot be redone (e.g. because the DOM state
is no longer consistent with the changes represented in the entry),
then the user agent must simply remove the <span>DOM changes</span>
entry, without doing anything else.</p>
<p>If the entry immediately after the <span>undo position</span> is
an <span>undo object</span> entry, then the user agent must first
remove that <span>undo object</span> entry from the <span>undo
transaction history</span>, and then must fire a <code
title="event-redo">redo</code> event at the <code>Window</code>
object, using the <span>undo object</span> entry's associated undo
object as the event's data.</p>
</div>
<h4>The <code>UndoManagerEvent</code> interface and the <code title="event-undo">undo</code> and <code title="event-redo">redo</code> events</h4>
<pre class="idl">interface <dfn>UndoManagerEvent</dfn> : Event {
readonly attribute any <span title="dom-UndoManagerEvent-data">data</span>;
void <span title="dom-UndoManagerEvent-initUndoManagerEvent">initUndoManagerEvent</span>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any dataArg);
};</pre>
<dl class="domintro">
<dt><var title="">event</var> . <code title="dom-UndoManagerEvent-data">data</code></dt>
<dd>
<p>Returns the data that was passed to the <code
title="dom-undomanager-add">add()</code> method.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-UndoManagerEvent-initUndoManagerEvent"><code>initUndoManagerEvent()</code></dfn>
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. <a
href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p>The <dfn title="dom-UndoManagerEvent-data"><code>data</code></dfn>
attribute represents the <span>undo object</span> for the event.</p>
<p>The <dfn title="event-undo"><code>undo</code></dfn> and <dfn
title="event-redo"><code>redo</code></dfn> events do not bubble,
cannot be canceled, and have no default action. When the user agent
fires one of these events it must use the
<code>UndoManagerEvent</code> interface, with the <code
title="dom-UndoManagerEvent-data">data</code> field containing the
relevant <span>undo object</span>.</p>
</div>
<div class="impl">
<h4>Implementation notes</h4>
<p>How user agents present the above conceptual model to the user is
not defined. The undo interface could be a filtered view of the
<span>undo transaction history</span>, it could manipulate the
<span>undo transaction history</span> in ways not described above,
and so forth. For example, it is possible to design a UA that
appears to have separate <span title="undo transaction history">undo
transaction histories</span> for each form control; similarly, it is
possible to design systems where the user has access to more undo
information than is present in the official (as described above)
<span>undo transaction history</span> (such as providing a
tree-based approach to document state). Such UI models should be
based upon the single <span>undo transaction history</span>
described in this section, however, such that to a script there is
no detectable difference.</p>
</div>
<h3>Editing APIs</h3>
<dl class="domintro">
<dt><var title="">document</var> . <code title="dom-document-execCommand">execCommand</code>(<var title="">commandId</var> [, <var title="">showUI</var> [, <var title="">value</var> ] ] )</dt>
<dd>
<p>Runs the action specified by the first argument, as described
in the list below. The second and third arguments sometimes affect
the action. (If they don't they are ignored.)</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-queryCommandEnabled">queryCommandEnabled</code>(<var title="">commandId</var>)</dt>
<dd>
<p>Returns whether the given command is enabled, as described in the list below.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-queryCommandIndeterm">queryCommandIndeterm</code>(<var title="">commandId</var>)</dt>
<dd>
<p>Returns whether the given command is indeterminate, as described in the list below.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-queryCommandState">queryCommandState</code>(<var title="">commandId</var>)</dt>
<dd>
<p>Returns the state of the command, as described in the list below.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-queryCommandSupported">queryCommandSupported</code>(<var title="">commandId</var>)</dt>
<dd>
<p>Returns true if the command is supported; otherwise, returns false.</p>
</dd>
<dt><var title="">document</var> . <code title="dom-document-queryCommandValue">queryCommandValue</code>(<var title="">commandId</var>)</dt>
<dd>
<p>Returns the value of the command, as described in the list below.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn id="execCommand"
title="dom-document-execCommand"><code>execCommand(<var
title="">commandId</var>, <var title="">showUI</var>, <var
title="">value</var>)</code></dfn> method on the
<code>HTMLDocument</code> interface allows scripts to perform
actions on the <span title="the selection">current selection</span>
or at the current caret position. Generally, these commands would be
used to implement editor UI, for example having a "delete" button on
a toolbar.</p>
<p>There are three variants to this method, with one, two, and three
arguments respectively. The <var title="">showUI</var> and <var
title="">value</var> parameters, even if specified, are ignored
except where otherwise stated.</p>
<p>When <code title="dom-document-execCommand">execCommand()</code>
is invoked, the user agent must follow the following steps:</p>
<ol>
<li>If the given <var title="">commandId</var> maps to an entry in
the list below whose "Enabled When" entry has a condition that is
currently false, do nothing; abort these steps.</li>
<li>Otherwise, execute the "Action" listed below for the given <var
title="">commandId</var>.</li>
</ol>
</div>
<p>A document is <dfn>ready for editing host commands</dfn> if it
has a selection that is entirely within an <span>editing
host</span>, or if it has no selection but its caret is inside an
<span>editing host</span>.</p>
<div class="impl">
<p>The <dfn
title="dom-document-queryCommandEnabled"><code>queryCommandEnabled(<var
title="">commandId</var>)</code></dfn> method, when invoked, must
return true if the condition listed below under "Enabled When" for
the given <var title="">commandId</var> is true, and false
otherwise.</p>
<p>The <dfn
title="dom-document-queryCommandIndeterm"><code>queryCommandIndeterm(<var
title="">commandId</var>)</code></dfn> method, when invoked, must
return true if the condition listed below under "Indeterminate When"
for the given <var title="">commandId</var> is true, and false
otherwise.</p>
<p>The <dfn
title="dom-document-queryCommandState"><code>queryCommandState(<var
title="">commandId</var>)</code></dfn> method, when invoked, must
return the value expressed below under "State" for the given <var
title="">commandId</var>.</p>
<p>The <dfn
title="dom-document-queryCommandSupported"><code>queryCommandSupported(<var
title="">commandId</var>)</code></dfn> method, when invoked, must
return true if the given <var title="">commandId</var> is in the
list below, and false otherwise.</p>
<p>The <dfn
title="dom-document-queryCommandValue"><code>queryCommandValue(<var
title="">commandId</var>)</code></dfn> method, when invoked, must
return the value expressed below under "Value" for the given <var
title="">commandId</var>.</p>
</div>
<p>The possible values for <var title="">commandId</var>, and their
corresponding meanings, are as follows. <span class="impl">These
values must be compared to the argument in an <span>ASCII
case-insensitive</span> manner.</span></p>
<dl>
<dt><dfn title="command-bold"><code>bold</code></dfn></dt>
<dd><strong>Summary</strong>: Toggles whether the selection is bold.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had requested that the selection <a
href="#contenteditable-wrapSemantic">be wrapped in the
semantics</a> of the <em><code>b</code></em> element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA).</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: True if the selection, or the caret, if
there is no selection, is, or is contained within, a
<code>b</code> element. False otherwise.</dd>
<dd><strong>Value</strong>: The string "<code title="">true</code>"
if the expression given for the "State" above is true, the string
"<code title="">false</code>" otherwise.</dd>
<dt><dfn title="command-createLink"><code>createLink</code></dfn></dt>
<dd><strong>Summary</strong>: Toggles whether the selection is a
link or not. If the second argument is true, and a link is to be
added, the user agent will ask the user for the address. Otherwise,
the third argument will be used as the address.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had requested that the selection <a
href="#contenteditable-wrapSemantic">be wrapped in the
semantics</a> of the <em><code>a</code></em> element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA). If the user agent creates an <code>a</code> element or
modifies an existing <code>a</code> element, then if the <var
title="">showUI</var> argument is present and has the value false,
then the value of the <var title="">value</var> argument must be
used as the <span>URL</span> of the link. Otherwise, the user agent
should prompt the user for the URL of the link.</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-delete"><code>delete</code></dfn></dt>
<dd><strong>Summary</strong>: Deletes the selection or the
character before the cursor.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had performed <a href="#contenteditable-delete">a backspace
operation</a>.</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-formatBlock"><code>formatBlock</code></dfn></dt>
<dd><strong>Summary</strong>: Wraps the selection in the element
given by the second argument. If the second argument doesn't
specify an element that is a <dfn><code title="">formatBlock</code>
candidate</dfn>, does nothing.</dd>
<dd class="impl">
<p><strong>Action</strong>: The user agent must run the following
steps:</p>
<ol>
<li><p>If the <var title="">value</var> argument wasn't
specified, abort these steps without doing anything.</p></li>
<li><p>If the <var title="">value</var> argument has a leading
U+003C LESS-THAN SIGN character (<) and a trailing U+003E
GREATER-THAN SIGN character (>), then remove the first and last
characters from <var title="">value</var>.</p></li>
<li>
<p>If <var title="">value</var> is (now) an <span>ASCII
case-insensitive</span> match for the tag name of an element
defined by this specification that is defined to be a
<span><code title="">formatBlock</code> candidate</span>, then,
for every position in the selection, take the nearest
<span><code title="">formatBlock</code> candidate</span>
ancestor element of that position that contains only
<span>phrasing content</span>, and, if that element is
<span>editable</span>, is not an <span>editing host</span>, and
has a parent element whose content model allows that parent to
contain any <span>flow content</span>, replace it with an
element in the HTML namespace whose name is <var
title="">value</var>, and move all the children that were in it
to the new element, and copy all the attributes that were on it
to the new element.</p>
<p>If there is no selection, then, where in the description
above refers to the selection, the user agent must act as if the
selection was an empty range (with just one position) at the
caret position.</p>
</li>
</ol>
</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-forwardDelete"><code>forwardDelete</code></dfn></dt>
<dd><strong>Summary</strong>: Deletes the selection or the
character after the cursor.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had performed <a href="#contenteditable-delete">a forward delete
operation</a>.</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-insertImage"><code>insertImage</code></dfn></dt>
<dd><strong>Summary</strong>: Toggles whether the selection is an
image or not. If the second argument is true, and an image is to be
added, the user agent will ask the user for the address. Otherwise,
the third argument will be used as the address.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act
as if the user had requested that the selection <a
href="#contenteditable-wrapSemantic">be wrapped in the
semantics</a> of the <em><code>img</code></em> element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA). If the user agent creates an <code>img</code> element or
modifies an existing <code>img</code> element, then if the <var
title="">showUI</var> argument is present and has the value false,
then the value of the <var title="">value</var> argument must be
used as the <span>URL</span> of the image. Otherwise, the user
agent should prompt the user for the URL of the image.</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-insertHTML"><code>insertHTML</code></dfn></dt>
<dd><strong>Summary</strong>: Replaces the selection with the value
of the third argument parsed as HTML.</dd>
<dd class="impl">
<p><strong>Action</strong>: The user agent must run the following
steps:</p>
<ol>
<li><p>If the document is an <span title="XML documents">XML
document</span>, then throw an <code>INVALID_ACCESS_ERR</code>
exception and abort these steps.</p></li><!-- v2 support XML? -->
<li><p>If the <var title="">value</var> argument wasn't
specified, abort these steps without doing anything.</p></li>
<li><p>If there is a selection, act as if the user had requested
that <a href="#contenteditable-delete">the selection be
deleted</a>.</p></li>
<li><p>Invoke the <span>HTML fragment parsing algorithm</span>
with an arbitrary orphan <code>body</code> element owned by the
same <code>Document</code> as the <i>context</i> element and with
the <var title="">value</var> argument as <i>input</i>.</p></li>
<li><p>Insert the nodes returned by the previous step into the
document at the location of the caret, firing any mutation events
as appropriate.</p></li>
</ol>
</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-insertLineBreak"><code>insertLineBreak</code></dfn></dt>
<dd><strong>Summary</strong>: Inserts a line break.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had <a href="#contenteditable-br">requested a line
separator</a>.</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-insertOrderedList"><code>insertOrderedList</code></dfn></dt>
<dd><strong>Summary</strong>: Toggles whether the selection is an ordered list.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had requested that the selection <a
href="#contenteditable-wrapSemantic">be wrapped in the
semantics</a> of the <code>ol</code> element (or unwrapped, or, if
there is no selection, have that semantic inserted or removed
— the exact behavior is UA-defined).</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-insertUnorderedList"><code>insertUnorderedList</code></dfn></dt>
<dd><strong>Summary</strong>: Toggles whether the selection is an unordered list.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had requested that the selection <a
href="#contenteditable-wrapSemantic">be wrapped in the
semantics</a> of the <code>ul</code> element (or unwrapped, or, if
there is no selection, have that semantic inserted or removed
— the exact behavior is UA-defined).</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-insertParagraph"><code>insertParagraph</code></dfn></dt>
<dd><strong>Summary</strong>: Inserts a paragraph break.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had performed a <a href="#contenteditable-breakBlock">break
block</a> editing action.</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-insertText"><code>insertText</code></dfn></dt>
<dd><strong>Summary</strong>: Inserts the text given in the third parameter.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had <a href="#contenteditable-insertText">inserted text</a>
corresponding to the <var title="">value</var> parameter.</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-italic"><code>italic</code></dfn></dt>
<dd><strong>Summary</strong>: Toggles whether the selection is italic.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had requested that the selection <a
href="#contenteditable-wrapSemantic">be wrapped in the
semantics</a> of the <em><code>i</code></em> element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA).</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: True if the selection, or the caret, if
there is no selection, is, or is contained within, a
<code>i</code> element. False otherwise.</dd>
<dd><strong>Value</strong>: The string "<code title="">true</code>"
if the expression given for the "State" above is true, the string
"<code title="">false</code>" otherwise.</dd>
<dt><dfn title="command-redo"><code>redo</code></dfn></dt>
<dd><strong>Summary</strong>: Acts as if the user had requested a redo.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must <span
title="do-redo">move forward one step</span> in its <span>undo
transaction history</span>, restoring the associated state. If the
<span>undo position</span> is at the end of the <span>undo
transaction history</span>, the user agent must do nothing. See the
<span>undo history</span>.</dd>
<dd><strong>Enabled When</strong>: The <span>undo position</span>
is not at the end of the <span>undo transaction
history</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-selectAll"><code>selectAll</code></dfn></dt>
<dd><strong>Summary</strong>: Selects all the editable content.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must change the
selection so that all the content in the currently focused
<span>editing host</span> is selected. If no <span>editing
host</span> is focused, then the content of the entire document
must be selected.</dd>
<dd><strong>Enabled When</strong>: Always.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-subscript"><code>subscript</code></dfn></dt>
<dd><strong>Summary</strong>: Toggles whether the selection is subscripted.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had requested that the selection <a
href="#contenteditable-wrapSemantic">be wrapped in the
semantics</a> of the <em><code>sub</code></em> element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA).</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: True if the selection, or the caret, if
there is no selection, is, or is contained within, a
<code>sub</code> element. False otherwise.</dd>
<dd><strong>Value</strong>: The string "<code title="">true</code>"
if the expression given for the "State" above is true, the string
"<code title="">false</code>" otherwise.</dd>
<dt><dfn title="command-superscript"><code>superscript</code></dfn></dt>
<dd><strong>Summary</strong>: Toggles whether the selection is superscripted.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must act as if the user
had requested that the selection <a
href="#contenteditable-wrapSemantic">be wrapped in the
semantics</a> of the <code>sup</code> element (or unwrapped, or, if
there is no selection, have that semantic inserted or removed
— the exact behavior is UA-defined).</dd>
<dd><strong>Enabled When</strong>: The document is <span>ready for
editing host commands</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: True if the selection, or the caret, if
there is no selection, is, or is contained within, a
<code>sup</code> element. False otherwise.</dd>
<dd><strong>Value</strong>: The string "<code title="">true</code>"
if the expression given for the "State" above is true, the string
"<code title="">false</code>" otherwise.</dd>
<dt><dfn title="command-undo"><code>undo</code></dfn></dt>
<dd><strong>Summary</strong>: Acts as if the user had requested an undo.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must <span
title="do-undo">move back one step</span> in its <span>undo
transaction history</span>, restoring the associated state. If the
<span>undo position</span> is at the start of the <span>undo
transaction history</span>, the user agent must do nothing. See the
<span>undo history</span>.</dd>
<dd><strong>Enabled When</strong>: The <span>undo position</span>
is not at the start of the <span>undo transaction
history</span>.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-unlink"><code>unlink</code></dfn></dt>
<dd><strong>Summary</strong>: Removes all links from the selection.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must remove all
<code>a</code> elements that have <code
title="attr-hyperlink-href">href</code> attributes and that are partially
or completely included in the current selection.</dd>
<dd><strong>Enabled When</strong>: The document has a selection
that is entirely within an <span>editing host</span> and that
contains (either partially or completely) at least one
<code>a</code> element that has an <code
title="attr-hyperlink-href">href</code> attribute.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt><dfn title="command-unselect"><code>unselect</code></dfn></dt>
<dd><strong>Summary</strong>: Unselects everything.</dd>
<dd class="impl"><strong>Action</strong>: The user agent must change the
selection so that nothing is selected.</dd>
<dd><strong>Enabled When</strong>: Always.</dd>
<dd><strong>Indeterminate When</strong>: Never.</dd>
<dd><strong>State</strong>: Always false.</dd>
<dd><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
<dt class="impl"><code><var title="">vendorID</var>-<var title="">customCommandID</var></code></dt>
<dd class="impl"><strong>Action</strong>: User agents may implement
vendor-specific extensions to this API. Vendor-specific extensions
to the list of commands should use the syntax <code><var
title="">vendorID</var>-<var title="">customCommandID</var></code>
so as to prevent clashes between extensions from different vendors
and future additions to this specification.</dd>
<dd class="impl"><strong>Enabled When</strong>: UA-defined.</dd>
<dd class="impl"><strong>Indeterminate When</strong>: UA-defined.</dd>
<dd class="impl"><strong>State</strong>: UA-defined.</dd>
<dd class="impl"><strong>Value</strong>: UA-defined.</dd>
<dt class="impl">Anything else</dt>
<dd class="impl"><strong>Action</strong>: User agents must do nothing.</dd>
<dd class="impl"><strong>Enabled When</strong>: Never.</dd>
<dd class="impl"><strong>Indeterminate When</strong>: Never.</dd>
<dd class="impl"><strong>State</strong>: Always false.</dd>
<dd class="impl"><strong>Value</strong>: Always the string "<code title="">false</code>".</dd>
</dl>
<!--
v2 (well, really v0):
"forecolor", "hilitecolor", "fontname", "fontsize", "justifyleft",
"justifycenter", "justifyright", "justifyfull", "indent", "outdent"
-->
<h2 id="workers">Web Workers</h2> <!--START workers--><!--END html--><!--END html5-->
<h3>Introduction</h3>
<h4>Scope</h4>
<p><i>This section is non-normative.</i></p>
<p>This specification defines an API for running scripts in the
background independently of any user interface scripts.</p>
<p>This allows for long-running scripts that are not interrupted by
scripts that respond to clicks or other user interactions, and
allows long tasks to be executed without yielding to keep the page
responsive.</p>
<p>Workers (as these background scripts are called herein) are
relatively heavy-weight, and are not intended to be used in large
numbers. For example, it would be inappropriate to launch one worker
for each pixel of a four megapixel image. The examples below show
some appropriate uses of workers.</p>
<p>Generally, workers are expected to be long-lived, have a high
start-up performance cost, and a high per-instance memory cost.</p>
<h4>Tutorial</h4>
<p><i>This section is non-normative.</i></p>
<p>There are a variety of uses that workers can be put to. The
following subsections show various examples of this use.</p>
<h5>A background number-crunching worker</h5>
<p><i>This section is non-normative.</i></p>
<p>The simplest use of workers is for performing a computationally
expensive task without interrupting the user interface.</p>
<p>In this example, the main document spawns a worker to
(naïvely) compute prime numbers, and progressively displays the
most recently found prime number.</p>
<p>The main page is as follows:</p>
<pre>EXAMPLE workers/primes/page.html</pre>
<p>The <code title="dom-Worker">Worker()</code> constructor call
creates a worker and returns a <code>Worker</code> object
representing that worker, which is used to communicate with the
worker. That object's <code
title="handler-Worker-onmessage">onmessage</code> event handler allows the code to receive messages from the worker.</p>
<p>The worker itself is as follows:</p>
<pre>EXAMPLE workers/primes/worker.js</pre>
<p>The bulk of this code is simply an unoptimized search for a prime
number. To send a message back to the page, the <code
title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage()</code>
method is used to post a message when a prime is found.</p>
<p><a href="http://www.whatwg.org/demos/workers/primes/page.html">View this example online</a>.</p>
<h5>A worker for updating a client-side database</h5>
<p><i>This section is non-normative.</i></p>
<p>In this example, the main document spawns a worker whose only
task is to listen for notifications from the server, and, when
appropriate, either add or remove data from the client-side
database.</p>
<p>Since no communication occurs between the worker and the main
page, the main page can start the worker by just doing:</p>
<pre><script>
new Worker('worker.js');
</script></pre>
<p>The worker itself is as follows:</p>
<pre>EXAMPLE workers/database-updater/worker.js</pre>
<p>This connects to the server using the <code>WebSocket</code>
mechanism and opens the local database (which, we presume, has been
created earlier). The worker then just listens for messages from the
server and acts on them as appropriate, forever (or until the main
page is closed).</p>
<p><a
href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
this example online</a>. (This example will not actually function,
since the server does not actually exist and the database is not
created by this sample code.)</p>
<h5>Worker used for background I/O</h5>
<p><i>This section is non-normative.</i></p>
<p>In this example, the main document uses two workers, one for
fetching stock updates for at regular intervals, and one for
fetching performing search queries that the user requests.</p>
<p>The main page is as follows:</p>
<pre>EXAMPLE workers/stocks/page.html</pre>
<p>The two workers use a common library for performing the actual
network calls. This library is as follows:</p>
<pre>EXAMPLE workers/stocks/io.js</pre>
<p>The stock updater worker is as follows:</p>
<pre>EXAMPLE workers/stocks/ticker.js</pre>
<p>The search query worker is as follows:</p>
<pre>EXAMPLE workers/stocks/searcher.js</pre>
<p><a href="http://www.whatwg.org/demos/workers/stocks/page.html">View this example online</a>.</p>
<h5>Shared workers</h5>
<p><i>This section is non-normative.</i></p>
<p>In this example, multiple windows (viewers) can be opened that
are all viewing the same map. All the windows share the same map
information, with a single worker coordinating all the viewers. Each
viewer can move around independently, but if they set any data on
the map, all the viewers are updated.</p>
<p>The main page isn't interesting, it merely provides a way to open
the viewers:</p>
<pre>EXAMPLE workers/multiviewer/page.html</pre>
<p>The viewer is more involved:</p>
<pre>EXAMPLE workers/multiviewer/viewer.html</pre>
<p>There are several key things worth noting about the way the
viewer is written.</p>
<p><strong>Multiple listeners</strong>. Instead of a single message
processing function, the code here attaches multiple event
listeners, each one performing a quick check to see if it is
relevant for the message. In this example it doesn't make much
difference, but if multiple authors wanted to collaborate using a
single port to communicate with a worker, it would allow for
independent code instead of changes having to all be made to a
single event handling function.</p>
<p>Registering event listeners in this way also allows you to
unregister specific listeners when you are done with them, as is
done with the <code title="">configure()</code> method in this
example.</p>
<p>Finally, the worker:</p>
<pre>EXAMPLE workers/multiviewer/worker.js</pre>
<p><strong>Connecting to multiple pages</strong>. The script uses
the <code
title="handler-SharedWorkerGlobalScope-onconnect">onconnect</code>
event listener to listen for multiple connections.</p>
<p><strong>Direct channels</strong>. When the worker receives a
"msg" message from one viewer naming another viewer, it sets up a
direct connection between the two, so that the two viewers can
communicate directly without the worker having to proxy all the
messages.</p>
<p><a href="http://www.whatwg.org/demos/workers/multiviewer/page.html">View this example online</a>.</p>
<h5>Delegation</h5>
<p><i>This section is non-normative.</i></p>
<p>With multicore CPUs becoming prevalent, one way to obtain better
performance is to split computationally expensive tasks amongst
multiple workers. In this example, a computationally expensive task
that is to be performed for every number from 1 to 10,000,000 is
farmed out to ten subworkers.</p>
<p>The main page is as follows, it just reports the result:</p>
<pre>EXAMPLE workers/multicore/page.html</pre>
<p>The worker itself is as follows:</p>
<pre>EXAMPLE workers/multicore/worker.js</pre>
<p>It consists of a loop to start the subworkers, and then a handler
that waits for all the subworkers to respond.</p>
<p>The subworkers are implemented as follows:</p>
<pre>EXAMPLE workers/multicore/core.js</pre>
<p>They receive two numbers in two events, perform the computation
for the range of numbers thus specified, and then report the result
back to the parent.</p>
<p><a href="http://www.whatwg.org/demos/workers/multicore/page.html">View this example online</a>.</p>
<h5>Providing libraries</h5>
<p><i>This section is non-normative.</i></p>
<p>Suppose that a cryptography library is made available that
provides three tasks:</p>
<dl>
<dt>Generate a public/private key pair</dt>
<dd>Takes a port, on which it will send two messages, first the
public key and then the private key.</dd>
<dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
<dd>Takes a port, to which any number of messages can be sent, the
first giving the public key, and the remainder giving the
plaintext, each of which is encrypted and then sent on that same
channel as the cyphertext. The user can close the port when it is
done encrypting content.</dd>
<dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
<dd>Takes a port, to which any number of messages can be sent, the
first giving the private key, and the remainder giving the
cyphertext, each of which is decrypted and then sent on that same
channel as the plaintext. The user can close the port when it is
done decrypting content.</dd>
</dl>
<p>The library itself is as follows:</p>
<pre>EXAMPLE workers/crypto/libcrypto-v1.js</pre>
<p>Note that the crypto functions here are just stubs and don't do
real cryptography.</p>
<p>This library could be used as follows:</p>
<pre>EXAMPLE workers/crypto/page.html</pre>
<p>A later version of the API, though, might want to offload all the
crypto work onto subworkers. This could be done as follows:</p>
<pre>EXAMPLE workers/crypto/libcrypto-v2.js</pre>
<p>The little subworkers would then be as follows.</p>
<p>For generating key pairs:</p>
<pre>EXAMPLE workers/crypto/libcrypto-v2-generator.js</pre>
<p>For encrypting:</p>
<pre>EXAMPLE workers/crypto/libcrypto-v2-encryptor.js</pre>
<p>For decrypting:</p>
<pre>EXAMPLE workers/crypto/libcrypto-v2-decryptor.js</pre>
<p>Notice how the users of the API don't have to even know that this
is happening — the API hasn't changed; the library can
delegate to subworkers without changing its API, even though it is
accepting data using message channels.</p>
<p><a href="http://www.whatwg.org/demos/workers/crypto/page.html">View this example online</a>.</p>
<!--END complete-->
<!--BOILERPLATE middle-w3c-api-intro-->
<!--BOILERPLATE middle-w3c-js-disclaimer-->
<!--START complete-->
<h3>Infrastructure</h3>
<p>There are two kinds of workers; dedicated workers, and shared
workers. Dedicated workers, once created, and are linked to their
creator; but message ports can be used to communicate from a
dedicated worker to multiple other browsing contexts or
workers. Shared workers, on the other hand, are named, and once
created any script running in the same <span>origin</span> can
obtain a reference to that worker and communicate with it.</p>
<h4>The global scope</h4>
<p>The global scope is the "inside" of a worker.</p>
<h5>The <code>WorkerGlobalScope</code> abstract interface</h5>
<pre class="idl">interface <dfn>WorkerGlobalScope</dfn> {
readonly attribute <span>WorkerGlobalScope</span> <span title="dom-WorkerGlobalScope-self">self</span>;
readonly attribute <span>WorkerLocation</span> <span title="dom-WorkerGlobalScope-location">location</span>;
void <span title="dom-WorkerGlobalScope-close">close</span>();
<!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
--> attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onerror">onerror</span>;
};
<span>WorkerGlobalScope</span> implements <span>WorkerUtils</span>;
<span>WorkerGlobalScope</span> implements <span>EventTarget</span>;</pre>
<p>The <dfn
title="dom-WorkerGlobalScope-self"><code>self</code></dfn> attribute
must return the <code>WorkerGlobalScope</code> object itself.</p>
<p>The <dfn
title="dom-WorkerGlobalScope-location"><code>location</code></dfn>
attribute must return the <code>WorkerLocation</code> object created
for the <code>WorkerGlobalScope</code> object when the worker was
created. It represents the <span>absolute URL</span> of the script
that was used to initialize the worker, after any redirects.</p>
<hr>
<p>When a script invokes the <dfn
title="dom-WorkerGlobalScope-close"><code>close()</code></dfn>
method on a <code>WorkerGlobalScope</code> object, the user agent
must run the following steps (atomically):</p>
<ol>
<li><p>Discard any <span title="concept-task">tasks</span> that
have been added to the <span>event loop</span>'s <span title="task
queue">task queues</span>.</p>
<!-- v2-onclose
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code title="event-close">close</code> at the
<code>WorkerGlobalScope</code> object.</p></li>
-->
<li><p>Set the worker's <code>WorkerGlobalScope</code> object's
<span title="dom-WorkerGlobalScope-closing">closing</span> flag to
true. (This prevents any further tasks from being queued.)</p></li>
<li><p>Disentangle all the ports in the list of <span>the worker's
ports</span>.</p></li>
</ol>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as IDL attributes, by
objects implementing the <code>WorkerGlobalScope</code>
interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<!-- v2-onclose <tr><td><dfn title="handler-WorkerGlobalScope-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
<tr><td><dfn title="handler-WorkerGlobalScope-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
</table>
<hr>
<p>The <code>WorkerGlobalScope</code> interface must not exist if
the interface's <span>relevant namespace object</span> is a
<code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a></p>
<h5>Dedicated workers and the <code>DedicatedWorkerGlobalScope</code> interface</h5>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <dfn>DedicatedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope</span> {
void <span title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</span>(in any message, in optional <span>MessagePortArray</span> ports);<!--
<span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
attribute <span>Function</span> <span title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</span>;
};</pre>
<p><code>DedicatedWorkerGlobalScope</code> objects act as if they
had an implicit <code>MessagePort</code> associated with them. This
port is part of a channel that is set up when the worker is created,
but it is not exposed. This object must never be garbage collected
before the <code>DedicatedWorkerGlobalScope</code> object.</p>
<p>All messages received by that port must immediately be retargeted
at the <code>DedicatedWorkerGlobalScope</code> object.</p>
<p>The <dfn
title="dom-DedicatedWorkerGlobalScope-postMessage"><code>postMessage()</code></dfn><!--
and <dfn
title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
method<!--s (startConversation)--> on
<code>DedicatedWorkerGlobalScope</code> objects must act as if, when
invoked, it<!--/they (startConversation)--> immediately invoked the
method of the same name on the port, with the same arguments, and
returned the same return value.</p>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as IDL attributes, by
objects implementing the <code>DedicatedWorkerGlobalScope</code>
interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-DedicatedWorkerGlobalScope-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
</table>
<p>For the purposes of the <span>application cache</span> networking
model, a dedicated worker is an extension of the <span>cache
host</span> from which it was created.</p>
<h5>Shared workers and the <code>SharedWorkerGlobalScope</code> inteface</h5>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <dfn>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope</span> {
readonly attribute DOMString <span title="dom-SharedWorkerGlobalScope-name">name</span>;
readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
attribute <span>Function</span> <span title="handler-SharedWorkerGlobalScope-onconnect">onconnect</span>;
};</pre>
<p>Shared workers receive message ports through <code
title="event-WorkerGlobalScope-connect">connect</code> events on
their global object for each connection.</p>
<p>The <dfn
title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
attribute must return the value it was assigned when the
<code>SharedWorkerGlobalScope</code> object was created by the
"<span>run a worker</span>" algorithm. Its value represents the name
that can be used to obtain a reference to the worker using the
<code>SharedWorker</code> constructor.</p>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as IDL attributes, by
objects implementing the <code>SharedWorkerGlobalScope</code>
interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-SharedWorkerGlobalScope-onconnect"><code>onconnect</code></dfn> <td> <code title="event-connect">connect</code>
</table>
<p>For the purposes of the <span>application cache</span> networking
model, a shared worker is its own <span>cache host</span>. The
<span>run a worker</span> algorithm takes care of associating the
worker with an <span>application cache</span>.</p>
<p class="note">The <code
title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code>
attribute returns the <code>ApplicationCache</code> object for the
worker.</p><!-- normative conf criteria is in the appcache section
-->
<h4>Origins of workers</h4>
<p>Both the <span>origin</span> and <span>effective script
origin</span> of scripts running in workers are the
<span>origin</span> of the <span>absolute URL</span> given in that
the worker's <code
title="dom-WorkerGlobalScope-location">location</code> attribute
represents.</p>
<h4>The event loop</h4>
<p>Each <code>WorkerGlobalScope</code> object has an <span>event
loop</span> distinct from those defined for <span title="unit of
related similar-origin browsing contexts">units of related
similar-origin browsing contexts</span>. This <span>event
loop</span> has no associated <span>browsing context</span>, and its
<span title="task queue">task queues</span> only have events,
callbacks, and networking activity as <span
title="concept-task">tasks</span>. The processing model of these
<span title="event loop">event loops</span> is defined below in the
<span>run a worker</span> algorithm.</p>
<p>Each <code>WorkerGlobalScope</code> object also has a <dfn
title="dom-WorkerGlobalScope-closing">closing</dfn> flag, which must
initially be false, but which can get set to true by the algorithms
in the processing model section below.</p>
<p>Once the <code>WorkerGlobalScope</code>'s <span
title="dom-WorkerGlobalScope-closing">closing</span> flag is set to
true, the <span>event loop</span>'s <span title="task queue">task
queues</span> must discard any further <span
title="concept-task">tasks</span> that would be added to them (tasks
already on the queue are unaffected except where otherwise
specified). Effectively, once the <span
title="dom-WorkerGlobalScope-closing">closing</span> flag is true,
timers stop firing, notifications for all pending asynchronous
operations are dropped, etc.</p>
<h4>The worker's lifetime</h4>
<p>Workers communicate with other workers and with <span
title="browsing context">browsing contexts</span> through <span
title="channel messaging">message channels</span> and their
<code>MessagePort</code> objects.</p>
<p>Each <code>WorkerGlobalScope</code> <var title="">worker global
scope</var> has a list of <dfn>the worker's ports</dfn>, which
consists of all the <code>MessagePort</code> objects that are
entangled with another port and that have one (but only one) port
owned by <var title="">worker global scope</var>. This list includes
<!--all the <code>MessagePort</code> objects that are in events
pending in the <span>event loop</span>, as well as (commented out
because in practice it makes no difference either way as far as I
can tell, and it would be hard to strictly implement since these
ports might not yet be across the thread boundary)--> the implicit
<code>MessagePort</code> in the case of <span
title="DedicatedWorkerGlobalScope">dedicated workers</span>.</p>
<p>Each <code>WorkerGlobalScope</code> also has a list of <dfn>the
worker's workers</dfn>. Initially this list is empty; it is
populated when the worker creates or obtains further workers.</p>
<p>Finally, each <code>WorkerGlobalScope</code> also has a list of
<dfn>the worker's <code>Document</code>s</dfn>. Initially this list
is empty; it is populated when the worker is created.</p>
<p>Whenever a <code>Document</code> <var title="">d</var> is <dfn
title="add a document to the worker's documents">added to the
worker's <code>Document</code>s</dfn>, the user agent must, for each
worker in the list of <span>the worker's workers</span> whose list
of <span>the worker's <code>Document</code>s</span> does not contain
<var title="">d</var>, <span title="add a document to the worker's
documents">add <var title="">d</var> to <var title="">q</var>'s
<code>WorkerGlobalScope</code> owner's list of <span>the worker's
<code>Document</code>s</span></span>.</p> <!-- suggestions welcome
on making this sentence into understandable English -->
<p>Whenever a <code>Document</code> object is <span title="discard a
Document">discarded</span>, it must be removed from the list of
<span>the worker's <code>Document</code>s</span> of each worker
whose list contains that <code>Document</code>.</p>
<p>Given a <span>script's global object</span> <var title="">o</var>
when creating or obtaining a worker, the <dfn>list of relevant
<code>Document</code> objects to add</dfn> depends on the type of
<var title="">o</var>. If <var title="">o</var> is a
<code>WorkerGlobalScope</code> object (i.e. if we are creating a
nested worker), then the relevant <code>Document</code>s are the
<code>Document</code>s that are in <var title="">o</var>'s own list
of <span>the worker's <code>Document</code>s</span>. Otherwise, <var
title="">o</var> is a <code>Window</code> object, and the relevant
<code>Document</code> is just the <code>Document</code> that is the
<span>active document</span> of the <code>Window</code> object <var
title="">o</var>.</p>
<hr>
<p>A worker is said to be a <dfn>permissible worker</dfn> if its
list of <span>the worker's <code>Document</code>s</span> is not
empty.</p>
<p>A worker is said to be a <dfn>protected worker</dfn> if it is a
<span>permissible worker</span> and either it has outstanding
timers, database transactions, or network connections, or its list
of <span>the worker's ports</span> is not empty, or its
<code>WorkerGlobalScope</code> is actually a
<code>SharedWorkerGlobalScope</code> object (i.e. the worker is a
shared worker).</p>
<p>A worker is said to be an <dfn>active needed worker</dfn> if any
of the <code>Document</code> objects in <span>the worker's
<code>Document</code>s</span> are <span>fully active</span>.</p>
<p>A worker is said to be a <dfn>suspendable worker</dfn> if it is
not an <span>active needed worker</span> but it is a
<span>permissible worker</span>.</p>
<h4>Processing model</h4>
<p>When a user agent is to <dfn>run a worker</dfn> for a script with
<span>URL</span> <var title="">url</var>, a browsing context <var
title="">owner browsing context</var>, an origin <var title="">owner
origin</var>, and with global scope <var title="">worker global
scope</var>, it must run the following steps:</p>
<ol>
<li>
<p>Create a completely separate and parallel execution environment
(i.e. a separate thread or process or equivalent construct), and
run the rest of these steps asynchronously in that context.</p>
</li>
<li><p>If <var title="">worker global scope</var> is actually a
<code>SharedWorkerGlobalScope</code> object (i.e. the worker is a
shared worker), and there are any <span title="relevant application
cache">relevant application caches</span> that are identified by a
manifest URL with the <span>same origin</span> as <var
title="">url</var> and that have <var title="">url</var> as one of
their entries, <em>not</em> excluding entries marked as <span
title="concept-appcache-foreign">foreign</span>, then associate the
<var title="">worker global scope</var> with the <span
title="concept-appcache-selection">most appropriate application
cache</span> of those that match.</p></li>
<li>
<p>Attempt to <span>fetch</span> the resource identified by <var
title="">url</var>, from the <var title="">owner origin</var>.</p>
<!-- not http-origin privacy sensitive -->
<p>If the attempt fails, or if the attempt involves any redirects
to URIs that do not have the <span>same origin</span> as <var
title="">url</var> (even if the final URI is at the <span>same
origin</span> as the original <var title="">url</var>), then for
each <code>Worker</code> or <code>SharedWorker</code> object
associated with <var title="">worker global scope</var>,
<span>queue a task</span> to <span>fire a simple event</span>
named <code title="event-error">error</code> at that
object. Abort these steps.</p>
<p>If the attempt succeeds, then convert the script resource to
Unicode by assuming it was encoded as UTF-8, to obtain its <var
title="">source</var>.</p>
<p>Let <var title="">language</var> be JavaScript.</p>
<p class="note">As with <code>script</code> elements, the MIME
type of the script is ignored. Unlike with <code>script</code>
elements, there is no way to override the type. It's always
assumed to be JavaScript.</p>
</li>
<li>
<p>A new <span title="concept-script">script</span> is now
created, as follows.</p>
<p>Create a new <span>script execution environment</span>
set up as appropriate for the scripting language <var
title="">language</var>.</p>
<p>Parse/compile/initialize <var title="">source</var> using that
<span>script execution environment</span>, as appropriate for <var
title="">language</var>, and thus obtain a <span>list of code
entry-points</span>; set the <i>initial code entry-point</i> to
the entry-point for any executable code to be immediately run.</p>
<p>Set the <span>script's global object</span> to <var
title="">worker global scope</var>.</p>
<p>Set the <span>script's browsing context</span> to <var
title="">owner browsing context</var>.</p>
<p>Set the <span>script's URL character encoding</span> to
UTF-8. (This is just used for encoding non-ASCII characters in the
query component of URLs.)</p>
<p>Set the <span>script's base URL</span> to <var
title="">url</var>.</p>
</li>
<li>
<p><strong>Closing orphan workers</strong>: Start monitoring the
worker such that no sooner than it stops being either a
<span>protected worker</span> or a <span>suspendable
worker</span>, and no later than it stops being a
<span>permissible worker</span>, <var title="">worker global
scope</var>'s <span
title="dom-WorkerGlobalScope-closing">closing</span> flag is set
to true<!-- v2-onclose and <span title="queue a task">a task is
queued</span> to <span>fire a simple event</span> named <code
title="event-close">close</code> at <var title="">worker global
scope</var>-->.</p>
</li>
<li>
<p><strong>Suspending workers</strong>: Start monitoring the
worker, such that whenever <var title="">worker global
scope</var>'s <span
title="dom-WorkerGlobalScope-closing">closing</span> flag is false
and the worker is a <span>suspendable worker</span>, the user
agent suspends execution of script in that worker until such time
as either the <span
title="dom-WorkerGlobalScope-closing">closing</span> flag switches
to true or the worker stops being a <span>suspendable
worker</span>.</p>
</li>
<li>
<p><span title="jump to a code entry-point">Jump</span> to the
<span title="concept-script">script</span>'s <i>initial code
entry-point</i>, and let that run until it either returns, fails
to catch an exception, or gets prematurely aborted by the
"<span>kill a worker</span>" or "<span>terminate a worker</span>"
algorithms defined below.</p>
<!-- v2-onclose
<p class="note">If the script gets aborted by the "<span>kill a
worker</span>" algorithm, then that same algorithm will cause
there to only be a single <span title="concept-task">task</span>
in the <span>event loop</span> at the next step, namely the task
for the <code title="message-close">close</code> event. The
"<span>terminate a worker</span>" algorithm removes all the
events.</p>
-->
</li>
<li><p>If <var title="">worker global scope</var> is actually a
<code>DedicatedWorkerGlobalScope</code> object (i.e. the worker is
a dedicated worker), then enable the <span>port message
queue</span> of the worker's implicit port.</p></li>
<li>
<p><i title="">Event loop</i>: Wait until either there is a <span
title="concept-task">task</span> in one of the <span>event
loop</span>'s <span title="task queue">task queues</span> or <var
title="">worker global scope</var>'s <span
title="dom-WorkerGlobalScope-closing">closing</span> flag is set
to true.</p>
</li>
<li>
<p>Run the oldest task on one of the <span>event loop</span>'s
<span title="task queue">task queues</span>, if any. The user
agent may pick any <span>task queue</span>.</p>
<p class="note">The handling of events or the execution of
callbacks might get prematurely aborted by the "<span>kill a
worker</span>" or "<span>terminate a worker</span>" algorithms
defined below.</p>
</li>
<li>
<p>Remove the task run in the previous step, if any, from its
<span>task queue</span>.</p>
</li>
<li>
<p>If there are any more events in the <span>event loop</span>'s
<span title="task queue">task queues</span> or if <var
title="">worker global scope</var>'s <span
title="dom-WorkerGlobalScope-closing">closing</span> flag is set
to false, then jump back to the step above labeled <i>event
loop</i>.</p>
</li>
<li>
<p>If there are any outstanding transactions that have callbacks
that involve <span title="concept-script">scripts</span> whose
<span title="script's global object">global object</span> is the
<var title="">worker global scope</var>, roll them back (without
invoking any of the callbacks).</p>
</li>
<li>
<p>Empty the <var title="">worker global scope</var>'s <span>list
of active timeouts</span> and its <span>list of active
intervals</span>.</p>
</li>
<!-- v2-onclose
<li>
<p>For each <code>Worker</code> or <code>SharedWorker</code>
object associated with <var title="">worker global scope</var>,
<span>queue a task</span> to <span>fire a simple event</span>
named <code title="event-close">close</code> at that object.</p>
</li>
-->
</ol>
<hr>
<p>When a user agent is to <dfn>kill a worker</dfn> it must
run the following steps in parallel with the worker's main loop (the
"<span>run a worker</span>" processing model defined above):</p>
<ol>
<!-- v2-onclose
<li><p>If the worker's <code>WorkerGlobalScope</code> object's
<span title="dom-WorkerGlobalScope-closing">closing</span> flag is
false, <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-close">close</code> at the
worker's <code>WorkerGlobalScope</code> object.</p></li>
-->
<li><p>Set the worker's <code>WorkerGlobalScope</code> object's <span
title="dom-WorkerGlobalScope-closing">closing</span> flag to
true.</p></li>
<!-- v2-onclose
<li><p>Wait a user-agent-defined amount of time. If the "<span>run
a worker</span>" processing model defined above immediately starts
running event listeners registered for the <code
title="event-close">close</code> event, this time should not be
zero — the idea is that the <code
title="event-close">close</code> event can be used to clean up
when shutting down unexpectedly.</p></li>
-->
<li><p>If there are any <span title="concept-task">tasks</span>
queued in the <span>event loop</span>'s <span title="task
queue">task queues</span><!-- v2-onclose other than the <code
title="event-close">close</code> event that this algorithm just
added-->, discard them without processing them.</p></li>
<!-- v2-onclose
<li><p>If the <code title="event-close">close</code> event that
this algorithm just queued hasn't yet been dispatched, then abort
the script currently running in the worker.</p></li>
-->
<li><p>Wait a user-agent-defined amount of time.</p></li>
<li><p>Abort the script currently running in the worker<!--
v2-onclose (if any script is running, then it will be a handler for
the <code title="event-close">close</code> event)-->.</p></li>
</ol>
<p>User agents may invoke the "<span>kill a worker</span>"
processing model on a worker at any time, e.g. in response to user
requests, in response to CPU quota management, or when a worker
stops being an <span>active needed worker</span> if the worker
continues executing even after its <span
title="dom-WorkerGlobalScope-closing">closing</span> flag was
set to true.</p>
<hr>
<p>When a user agent is to <dfn>terminate a worker</dfn> it must run
the following steps in parallel with the worker's main loop (the
"<span>run a worker</span>" processing model defined above):</p>
<ol>
<li><p>Set the worker's <code>WorkerGlobalScope</code> object's
<span title="dom-WorkerGlobalScope-closing">closing</span> flag to
true.</p></li>
<li><p>If there are any <span title="concept-task">tasks</span>
queued in the <span>event loop</span>'s <span title="task
queue">task queues</span>, discard them without processing
them.</p></li>
<li><p>Abort the script currently running in the worker.</p></li>
<li><p>If the worker's <code>WorkerGlobalScope</code> object is
actually a <code>DedicatedWorkerGlobalScope</code> object (i.e. the
worker is a dedicated worker), then empty the <span>port message
queue</span> of the port that the worker's implicit port is
entangled with.</p></li>
</ol>
<hr>
<p>The <span>task source</span> for the tasks mentioned above is the
<span>DOM manipulation task source</span>.</p>
<h4>Runtime script errors</h4>
<p>Whenever an uncaught runtime script error occurs in one of the
worker's scripts, if the error did not occur while handling a
previous script error, the user agent must <span>report the
error</span> using the <code>WorkerGlobalScope</code> object's <code
title="handler-WorkerGlobalScope-onerror">onerror</code>
attribute.
<!--END complete-->
<a href="#refsHTML5">[HTML5]</a>
<!--START complete-->
</p>
<p>For shared workers, if the error is still <i
title="concept-error-nothandled">not handled</i> afterwards, or if
the error occurred while handling a previous script error, the error
should be reported to the user.
<!--END complete-->
<a href="#refsHTML5">[HTML5]</a>
<!--START complete-->
</p>
<p>For dedicated workers, if the error is still <i
title="concept-error-nothandled">not handled</i> afterwards, or if
the error occurred while handling a previous script error, the user
agent must <span>queue a task</span> to <span>fire a worker error
event</span> at the <code>Worker</code> object associated with the
worker.</p>
<p>When the user agent is to <dfn>fire a worker error event</dfn> at
a <code>Worker</code> object, it must dispatch an event that uses
the <code>ErrorEvent</code> interface, with the name <code
title="event-error">error</code>, that doesn't bubble and is
cancelable, with its <code
title="dom-ErrorEvent-message">message</code>, <code
title="dom-ErrorEvent-filename">filename</code>, and <code
title="dom-ErrorEvent-lineno">lineno</code> attributes set
appropriately. The default action of this event depends on whether
the <code>Worker</code> object is itself in a worker. If it is, and
that worker is also a dedicated worker, then the user agent must
again <span>queue a task</span> to <span>fire a worker error
event</span> at the <code>Worker</code> object associated with
<em>that</em> worker. Otherwise, then the error should be reported
to the user.</p>
<p>The <span>task source</span> for the tasks mentioned above is the
<span>DOM manipulation task source</span>.</p>
<hr>
<pre class="idl">interface <dfn>ErrorEvent</dfn> : Event {
readonly attribute DOMString <span title="dom-ErrorEvent-message">message</span>;
readonly attribute DOMString <span title="dom-ErrorEvent-filename">filename</span>;
readonly attribute unsigned long <span title="dom-ErrorEvent-lineno">lineno</span>;
void <span title="dom-ErrorEvent-initErrorEvent">initErrorEvent</span>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString messageArg, in DOMString filenameArg, in unsigned long linenoArg);
};</pre>
<p>The <dfn
title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. <a
href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p>The <dfn title="dom-ErrorEvent-message"><code>message</code></dfn>
attribute represents the error message.</p>
<p>The <dfn
title="dom-ErrorEvent-filename"><code>filename</code></dfn>
attribute represents the <span>absolute URL</span> of the script in
which the error originally occurred.</p>
<p>The <dfn title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
attribute represents the line number where the error occurred in the
script.</p>
<h4>Creating workers</h4>
<h5>The <code>AbstractWorker</code> abstract interface</h5>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <dfn>AbstractWorker</dfn> {
attribute <span>Function</span> <span title="handler-AbstractWorker-onerror">onerror</span>;
<!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
};
<span>AbstractWorker</span> implements <span>EventTarget</span>;</pre>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as IDL attributes, by
objects implementing the <code>AbstractWorker</code> interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-AbstractWorker-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
<!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
</table>
<h5>Dedicated workers and the <code>Worker</code> interface</h5>
<pre class="idl">[<span title="dom-Worker">Constructor</span>(in DOMString scriptURL)]
interface <dfn>Worker</dfn> : <span>AbstractWorker</span> {
void <span title="dom-Worker-terminate">terminate</span>();
void <span title="dom-Worker-postMessage">postMessage</span>(in any message, in optional <span>MessagePortArray</span> ports);<!--
<span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
attribute <span>Function</span> <span title="handler-Worker-onmessage">onmessage</span>;
};</pre>
<p>The <dfn
title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
when invoked, must cause the "<span>terminate a worker</span>"
algorithm to be run on the worker with with the object is
associated.</p>
<p><code>Worker</code> objects act as if they had an implicit
<code>MessagePort</code> associated with them. This port is part of
a channel that is set up when the worker is created, but it is not
exposed. This object must never be garbage collected before the
<code>Worker</code> object.</p>
<p>All messages received by that port must immediately be retargeted
at the <code>Worker</code> object.</p>
<p>The <dfn
title="dom-Worker-postMessage"><code>postMessage()</code></dfn><!--
and <dfn
title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
method<!--s (startConversation)--> on <code>Worker</code> objects
must act as if, when invoked, it<!--/they (startConversation)-->
immediately invoked the method of the same name on the port, with
the same arguments, and returned the same return value.</p>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as IDL attributes, by
objects implementing the <code>Worker</code> interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
</table>
<hr>
<p>When the <dfn title="dom-Worker"><code>Worker(<var
title="">scriptURL</var>)</code></dfn> constructor is invoked, the
user agent must run the following steps:</p>
<ol>
<li><p><span title="resolve a url">Resolve</span> the <var
title="">scriptURL</var> argument relative to the <span>first
script</span>'s <span title="script's base URL">base URL</span>,
when the method is invoked.</p></li>
<li><p>If this fails, throw a <code>SYNTAX_ERR</code>
exception.</p></li>
<li>
<p>If the <span>origin</span> of the resulting <span>absolute
URL</span> is not the <span title="same origin">same</span> as the
origin of the <span>first script</span>, then throw a
<code>SECURITY_ERR</code> exception.</p>
<p class="note">Thus, scripts must be external files with the same
scheme as the original page: you can't load a script from a <code
title="">data:</code> URL or <code title="">javascript:</code>
URL, and a <code>https:</code> page couldn't start workers using
scripts with <code>http:</code> URLs.</p>
</li>
<li><p>Create a new <code>DedicatedWorkerGlobalScope</code>
object. Let <var title="">worker global scope</var> be this new
object.</p></li>
<li><p>Create a new <code>Worker</code> object, associated with
<var title="">worker global scope</var>. Let <var
title="">worker</var> be this new object.</p></li>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by the <span title="script's global object">global
object</span> of the <span title="concept-script">script</span> that
invoked the constructor. Let this be the <var title="">outside
port</var>.</p></li>
<li><p>Associate the <var title="">outside port</var> with <var
title="">worker</var>.</p></li>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by <var title="">worker global scope</var>. Let <var
title="">inside port</var> be this new object.</p></li>
<li><p>Associate <var title="">inside port</var> with <var
title="">worker global scope</var>.</p></li>
<li><p><span>Entangle</span> <var title="">outside port</var> and
<var title="">inside port</var>.</p></li>
<li><p>Return <var title="">worker</var>, and run the following
steps asynchronously.</p></li>
<!-- (this is done by the "run a worker" algorithm)
<li><p>Enable <var title="">inside port</var>'s <span>port message
queue</span>.</p></li>
-->
<li><p>Enable <var title="">outside port</var>'s <span>port message
queue</span>.</p></li>
<li>
<p>Let <var title="">docs</var> be the <span>list of relevant
<code>Document</code> objects to add</span> given the <span
title="script's global object">global object</span> of the <span
title="concept-script">script</span> that invoked the
constructor.</p>
</li>
<li>
<p><span title="add a document to the worker's documents">Add to
<var title="">worker global scope</var>'s list of <span>the
worker's <code>Document</code>s</span></span> the
<code>Document</code> objects in <var title="">docs</var>.</p>
</li>
<li>
<p>If the <span title="script's global object">global object</span>
of the <span title="concept-script">script</span> that invoked the
constructor is a <code>WorkerGlobalScope</code> object (i.e. we
are creating a nested worker), add <var title="">worker global
scope</var> to the list of <span>the worker's workers</span> of the
<code>WorkerGlobalScope</code> object that is the <span
title="script's global object">global object</span> of the <span
title="concept-script">script</span> that invoked the
constructor.</p>
</li>
<li>
<p><span>Run a worker</span> for the resulting <span>absolute
URL</span>, with the <span>script's browsing context</span> of the
script that invoked the method as the <var title="">owner browsing
context</var>, with the <span>origin</span> of the <span>first
script</span> as the <var title="">owner origin</var>, and with
<var title="">worker global scope</var> as the global scope.</p>
</li>
</ol>
<p>This constructor must be visible when the <span>script's global
object</span> is either a <code>Window</code> object or an object
implementing the <code>WorkerUtils</code> interface.</p>
<h5>Shared workers and the <code>SharedWorker</code> interface</h5>
<pre class="idl">[<span title="dom-SharedWorker">Constructor</span>(in DOMString scriptURL, in optional DOMString name)]
interface <dfn>SharedWorker</dfn> : <span>AbstractWorker</span> {
readonly attribute <span>MessagePort</span> <span title="dom-SharedWorker-port">port</span>;
};</pre>
<p>The <dfn title="dom-SharedWorker-port"><code>port</code></dfn>
attribute must return the value it was assigned by the object's
constructor. It represents the <code>MessagePort</code> for
communicating with the shared worker.</p>
<p>When the <dfn title="dom-SharedWorker"><code>SharedWorker(<var
title="">scriptURL</var>, <var title="">name</var>)</code></dfn>
constructor is invoked, the user agent must run the following
steps:</p>
<ol>
<li><p><span title="resolve a url">Resolve</span> the <var
title="">scriptURL</var> argument.</p></li>
<li><p>If this fails, throw a <code>SYNTAX_ERR</code>
exception.</p></li>
<li><p>Otherwise, let <var title="">scriptURL</var> be the
resulting <span>absolute URL</span>.</p></li>
<li><p>Let <var title="">name</var> be the value of the second
argument, or the empty string if the second argument was
omitted.</p></li>
<li>
<p>If the <span>origin</span> of <var title="">scriptURL</var> is
not the <span title="same origin">same</span> as the origin of the
<span>first script</span>, then throw a <code>SECURITY_ERR</code>
exception.</p>
<p class="note">Thus, scripts must be external files with the same
scheme as the original page: you can't load a script from a <code
title="">data:</code> URL or <code title="">javascript:</code>
URL, and a <code>https:</code> page couldn't start workers using
scripts with <code>http:</code> URLs.</p>
</li>
<li>
<p>Let <var title="">docs</var> be the <span>list of relevant
<code>Document</code> objects to add</span> given the <span
title="script's global object">global object</span> of the <span
title="concept-script">script</span> that invoked the
constructor.</p>
</li>
<li>
<p>Execute the following substeps atomically:</p>
<ol>
<li><p>Create a new <code>SharedWorker</code> object, which will
shortly be associated with a <code>SharedWorkerGlobalScope</code>
object. Let this <code>SharedWorker</code> object be <var
title="">worker</var>.</p></li>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by the <span title="script's global object">global
object</span> of the script that invoked the method. Let this be
the <var title="">outside port</var>.</p></li>
<li><p>Assign <var title="">outside port</var> to the <code
title="dom-SharedWorker-port">port</code> attribute of <var
title="">worker</var>.</p></li>
<li><p>Let <var title="">worker global scope</var> be
null.</p></li>
<li><p>If <var title="">name</var> is not the empty string and
there exists a <code>SharedWorkerGlobalScope</code> object whose
<span title="dom-WorkerGlobalScope-closing">closing</span> flag
is false, whose <code
title="dom-WorkerGlobalScope-name">name</code> attribute is
exactly equal to <var title="">name</var>, and whose <code
title="dom-WorkerGlobalScope-location">location</code> attribute
represents an <span>absolute URL</span> with the <span>same
origin</span> as <var title="">scriptURL</var>, then let <var
title="">worker global scope</var> be that
<code>SharedWorkerGlobalScope</code> object.</p></li>
<li><p>Otherwise, if <var title="">name</var> is the empty string
and there exists a <code>SharedWorkerGlobalScope</code> object
whose <span title="dom-WorkerGlobalScope-closing">closing</span>
flag is false, and whose <code
title="dom-WorkerGlobalScope-location">location</code> attribute
is exactly equal to <var title="">scriptURL</var>, then let <var
title="">worker global scope</var> be that
<code>SharedWorkerGlobalScope</code> object.</p></li>
<li>
<p>If <var title="">worker global scope</var> is not null, then
run these steps:</p>
<ol>
<li><p>If <var title="">worker global scope</var>'s <code
title="dom-WorkerGlobalScope-location">location</code>
attribute represents an <span>absolute URL</span> that is not
exactly equal to <var title="">scriptURL</var>, then throw a
<code>URL_MISMATCH_ERR</code> exception and abort all these
steps.</p></li>
<li><p>Associate <var title="">worker</var> with <var
title="">worker global scope</var>.</p></li>
<li><p><span>Create a new <code>MessagePort</code>
object</span> owned by <var title="">worker global
scope</var>. Let this be the <var title="">inside
port</var>.</p></li>
<li><p><span>Entangle</span> <var title="">outside port</var>
and <var title="">inside port</var>.</p></li>
<li><p>Return <var title="">worker</var> and perform the next
step asynchronously.</p></li>
<li><p>Create an event that uses the <code>MessageEvent</code>
interface, with the name <code
title="event-connect">connect</code>, which does not bubble, is
not cancelable, has no default action, has a <code
title="dom-MessageEvent-data">data</code> attribute whose value
is the empty string and has a <code
title="dom-MessageEvent-ports">ports</code> attribute whose
value is an array containing only the newly created port, and
<span>queue a task</span> to dispatch the event at <var
title="">worker global scope</var>.</p></li>
<li>
<p><span title="add a document to the worker's documents">Add to
<var title="">worker global scope</var>'s list of <span>the
worker's <code>Document</code>s</span></span> the
<code>Document</code> objects in <var title="">docs</var>.</p>
</li>
<li>
<p>If the <span title="script's global object">global
object</span> of the <span title="concept-script">script</span>
that invoked the constructor is a
<code>WorkerGlobalScope</code> object, add <var
title="">worker global scope</var> to the list of <span>the
worker's workers</span> of the <code>WorkerGlobalScope</code>
object that is the <span title="script's global object">global
object</span> of the <span title="concept-script">script</span>
that invoked the constructor.</p>
</li>
<li><p>Abort all these steps.</p></li>
</ol>
</li>
<li><p>Create a new <code>SharedWorkerGlobalScope</code>
object. Let <var title="">worker global scope</var> be this new
object.</p></li>
<li><p>Associate <var title="">worker</var> with <var
title="">worker global scope</var>.</p></li>
<li><p>Set the <code
title="dom-SharedWorkerGlobalScope-name">name</code> attribute of
<var title="">worker global scope</var> to <var
title="">name</var>.</p></li>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by <var title="">worker global scope</var>. Let <var
title="">inside port</var> be this new object.</p></li>
<li><p><span>Entangle</span> <var title="">outside port</var> and
<var title="">inside port</var>.</p></li>
</ol>
</li>
<li><p>Return <var title="">worker</var> and perform the remaining
steps asynchronously.</p></li>
<li><p>Create an event that uses the <code>MessageEvent</code>
interface, with the name <code
title="event-connect">connect</code>, which does not bubble, is not
cancelable, has no default action, has a <code
title="dom-MessageEvent-data">data</code> attribute whose value is
the empty string and has a <code
title="dom-MessageEvent-ports">ports</code> attribute whose value
is an array containing only the newly created port, and <span>queue
a task</span> to dispatch the event at <var title="">worker global
scope</var>.</p></li>
<li>
<p><span title="add a document to the worker's documents">Add to
<var title="">worker global scope</var>'s list of <span>the
worker's <code>Document</code>s</span></span> the
<code>Document</code> objects in <var title="">docs</var>.</p>
</li>
<li>
<p>If the <span title="script's global object">global object</span>
of the <span title="concept-script">script</span> that invoked the
constructor is a <code>WorkerGlobalScope</code> object, add <var
title="">worker global scope</var> to the list of <span>the
worker's workers</span> of the <code>WorkerGlobalScope</code>
object that is the <span title="script's global object">global
object</span> of the <span title="concept-script">script</span>
that invoked the constructor.</p>
</li>
<li>
<p><span>Run a worker</span> for <var title="">scriptURL</var>,
with the <span>script's browsing context</span> of the script that
invoked the method as the <var title="">owner browsing
context</var>, with the <span>origin</span> of the <span>first
script</span> as the <var title="">owner origin</var>, and with
<var title="">worker global scope</var> as the global scope.</p>
</li>
</ol>
<p>This constructor must be visible when the <span>script's global
object</span> is either a <code>Window</code> object or an object
implementing the <code>WorkerUtils</code> interface.</p>
<p>The <span>task source</span> for the tasks mentioned above is the
<span>DOM manipulation task source</span>.</p>
<h3>APIs available to workers</h3>
<pre class="idl">[Supplemental, NoInterfaceObject]
interface <dfn>WorkerUtils</dfn> {
void <span title="dom-WorkerGlobalScope-importScripts">importScripts</span>(in DOMString... urls);
readonly attribute <span>WorkerNavigator</span> <span title="dom-worker-navigator">navigator</span>;
};
<span>WorkerUtils</span> implements <span>WindowTimers</span>;</pre>
<p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
objects, etc) are not available to workers in this version of this
specification.</p>
<h4>Importing scripts and libraries</h4>
<p>When a script invokes the <dfn
title="dom-WorkerGlobalScope-importScripts"><code>importScripts(<var
title="">urls</var>)</code></dfn> method on a
<code>WorkerGlobalScope</code> object, the user agent must run the
following steps:</p>
<ol>
<li><p>If there are no arguments, return without doing
anything. Abort these steps.</p></li>
<li><p><span title="resolve a url">Resolve</span> each
argument.</p></li>
<li><p>If any fail, throw a <code>SYNTAX_ERR</code>
exception.</p></li>
<!--
<li><p>If any of the resulting <span title="absolute URL">absolute
URLs</span> have an <span>origin</span> that is not the <span
title="same origin">same</span> as the origin of the script that
invoked the method, then throw a <code>SECURITY_ERR</code>
exception.</p></li>
-->
<li>
<p>Attempt to <span>fetch</span> each resource identified by the
resulting <span title="absolute URL">absolute URLs</span>, from
the <span>first script</span>'s <span>origin</span>.</p> <!-- not
http-origin privacy sensitive -->
</li>
<li>
<p>For each argument in turn, in the order given, starting with
the first one, run these substeps:</p>
<ol>
<li>
<p>Wait for the fetching attempt for the corresponding resource
to complete.</p>
<p>If the fetching attempt failed, throw a
<code>NETWORK_ERR</code> exception and abort all these
steps.</p>
<p>If the attempt succeeds, then convert the script resource to
Unicode by assuming it was encoded as UTF-8, to obtain its <var
title="">source</var>.</p>
<p>Let <var title="">language</var> be JavaScript.</p>
<p class="note">As with the worker's script, the script here is
always assumed to be JavaScript, regardless of the MIME
type.</p>
</li>
<li>
<p><span>Create a script</span>, using <var
title="">source</var> as the script source and <var
title="">language</var> as the scripting language, using the
same global object, browsing context, URL character encoding,
base URL, and script group as the <span
title="concept-script">script</span> that was created by the
worker's <span>run a worker</span> algorithm.</p>
<p>Let the newly created <span
title="concept-script">script</span> run until it either
returns, fails to parse, fails to catch an exception, or gets
prematurely aborted by the "<span>kill a worker</span>" or
"<span>terminate a worker</span>" algorithms defined above.</p>
<p>If it failed to parse, then throw an ECMAScript
<code>SyntaxError</code> exception and abort all these
steps. <a href="#refsECMA262">[ECMA262]</a></p>
<p>If an exception was raised or if the script was prematurely
aborted, then abort all these steps, letting the exception or
aborting continue to be processed by the script that called the
<code
title="dom-WorkerGlobalScope-importScripts">importScripts()</code>
method.</p>
<p>If the "<span>kill a worker</span>" or "<span>terminate a
worker</span>" algorithms abort the script then abort all these
steps.</p>
</li>
</ol>
</li>
</ol>
<h4>The <code>WorkerNavigator</code> object</h4>
<p>The <dfn
title="dom-worker-navigator"><code>navigator</code></dfn> attribute
of the <code>WorkerUtils</code> interface must return an instance of
the <code>WorkerNavigator</code> interface, which represents the
identity and state of the user agent (the client):</p>
<pre class="idl">interface <dfn>WorkerNavigator</dfn> {};
<span>WorkerNavigator</span> implements <span>NavigatorID</span>;
<span>WorkerNavigator</span> implements <span>NavigatorOnLine</span>;</pre>
<p>Objects implementing the <code>WorkerNavigator</code> interface
also implement the <code>NavigatorID</code> and
<code>NavigatorOnLine</code> interfaces.
<!--END complete-->
<a href="#refsHTML5">[HTML5]</a>
<!--START complete-->
</p>
<p>This <code>WorkerNavigator</code> interface must not exist if the
interface's <span>relevant namespace object</span> is a
<code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a></p>
<h4>APIs defined in other specifications</h4>
<p>The <code title="dom-opendatabase">openDatabase()</code> and
<code title="dom-opendatabase-sync">openDatabaseSync()</code>
methods are defined in the Web SQL Database specification. <a
href="#refsWEBSQL">[WEBSQL]</a></p>
<h4>Interface objects and constructors</h4>
<p>There must be no interface objects and constructors available in
the global scope of scripts whose <span>script's global
object</span> is a <code>WorkerGlobalScope</code> object except for
the following:</p>
<ul>
<li><p><code>XMLHttpRequest</code> and all interface objects and
constructors defined by the XMLHttpRequest specifications, except
that the <span>document response entity body</span> must always be
null. The <span><code>XMLHttpRequest</code> base URL</span> is the
<span>script's base URL</span>; the
<span><code>XMLHttpRequest</code> origin</span> is the script's
<span>origin</span>. <a href="#refsXHR">[XHR]</a></p></li>
<li><p>The interface objects and constructors defined by this
specification.</p></li>
<li><p>Constructors defined by specifications that explicitly say
that they should be visible when the <span>script's global
object</span> is a <code>DedicatedWorkerGlobalScope</code>, a
<code>SharedWorkerGlobalScope</code>, or an object implementing the
<code>WorkerUtils</code> interface; the interfaces of any objects
with such constructors; and the interfaces of any objects made
accessible through APIs exposed by those constructors or made
accessible through interfaces to be implemented by any objects that
are themselves accessible to scripts whose <span>script's global
object</span> implements the <code>WorkerUtils</code>
interface.</p></li>
</ul>
<p class="note">These requirements do not override the requirements
defined by the Web IDL specification, in particular concerning the
visibility of interfaces annotated with the <code
title="">[NoInterfaceObject]</code> extended attribute.</p>
<h4>Worker locations</h4>
<pre class="idl">interface <dfn>WorkerLocation</dfn> {
readonly attribute DOMString <span title="dom-WorkerLocation-href">href</span>;
readonly attribute DOMString <span title="dom-WorkerLocation-protocol">protocol</span>;
readonly attribute DOMString <span title="dom-WorkerLocation-host">host</span>;
readonly attribute DOMString <span title="dom-WorkerLocation-hostname">hostname</span>;
readonly attribute DOMString <span title="dom-WorkerLocation-port">port</span>;
readonly attribute DOMString <span title="dom-WorkerLocation-pathname">pathname</span>;
readonly attribute DOMString <span title="dom-WorkerLocation-search">search</span>;
readonly attribute DOMString <span title="dom-WorkerLocation-hash">hash</span>;
};</pre>
<p>A <code>WorkerLocation</code> object represents an <span>absolute
URL</span> set at its creation.</p>
<p>The <dfn title="dom-WorkerLocation-href"><code>href</code></dfn>
attribute must return the <span>absolute URL</span> that the object
represents.</p>
<p>The <code>WorkerLocation</code> interface also has the complement
of <span>URL decomposition IDL attributes</span>, <dfn
title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
<dfn title="dom-WorkerLocation-host"><code>host</code></dfn>, <dfn
title="dom-WorkerLocation-port"><code>port</code></dfn>, <dfn
title="dom-WorkerLocation-hostname"><code>hostname</code></dfn>,
<dfn
title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
<dfn title="dom-WorkerLocation-search"><code>search</code></dfn>,
and <dfn
title="dom-WorkerLocation-hash"><code>hash</code></dfn>. These must
follow the rules given for URL decomposition IDL attributes, with the
<span title="concept-uda-input">input</span> being the
<span>absolute URL</span> that the object represents (same as the
<code title="dom-WorkerLocation-href">href</code> attribute), and
the <span title="concept-uda-setter">common setter action</span>
being a no-op, since the attributes are defined to be readonly.
<!--END complete-->
<a href="#refsHTML5">[HTML5]</a>
<!--START complete-->
</p>
<p>The <code>WorkerLocation</code> interface must not exist if the
interface's <span>relevant namespace object</span> is a
<code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a></p>
<!--END workers--><!--START html--><!--START html5-->
<h2 id="comms">Communication</h2>
<h3>Event definitions</h3>
<p>Messages in <span>server-sent events</span>, <span>Web
sockets</span>, <span>cross-document messaging</span>, and
<span>channel messaging</span> use the <dfn
title="event-message"><code>message</code></dfn> event.
<!--END complete-->
<a href="#refsEVENTSOURCE">[EVENTSOURCE]</a>
<a href="#refsWEBSOCKET">[WEBSOCKET]</a>
<!--START complete-->
</p>
<p>The following interface is defined for this event:</p>
<pre class="idl">interface <dfn>MessageEvent</dfn> : Event {
readonly attribute any <span title="dom-MessageEvent-data">data</span>;
readonly attribute DOMString <span title="dom-MessageEvent-origin">origin</span>;
readonly attribute DOMString <span title="dom-MessageEvent-lastEventId">lastEventId</span>;
readonly attribute <span>WindowProxy</span> <span title="dom-MessageEvent-source">source</span>;
readonly attribute <span>MessagePortArray</span> <span title="dom-MessageEvent-ports">ports</span>;
void <span title="dom-MessageEvent-initMessageEvent">initMessageEvent</span>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any dataArg, in DOMString originArg, in DOMString lastEventIdArg, in <span>WindowProxy</span> sourceArg, in <span>MessagePortArray</span> portsArg);
};</pre>
<dl class="domintro">
<dt><var title="">event</var> . <code title="dom-MessageEvent-data">data</code></dt>
<dd>
<p>Returns the data of the message.</p>
</dd>
<dt><var title="">event</var> . <code title="dom-MessageEvent-origin">origin</code></dt>
<dd>
<p>Returns the origin of the message, for <span>server-sent
events</span> and <span>cross-document messaging</span>.</p>
</dd>
<dt><var title="">event</var> . <code title="dom-MessageEvent-lastEventId">lastEventId</code></dt>
<dd>
<p>Returns the last event ID, for <span>server-sent
events</span>.</p>
</dd>
<dt><var title="">event</var> . <code title="dom-MessageEvent-source">source</code></dt>
<dd>
<p>Returns the <code>WindowProxy</code> of the source window, for
<span>cross-document messaging</span>.</p>
</dd>
<dt><var title="">event</var> . <code title="dom-MessageEvent-ports">ports</code></dt>
<dd>
<p>Returns the <code>MessagePortArray</code> sent with the
message, for <span>cross-document messaging</span> and
<span>channel messaging</span>.</p>
</dd>
</dl>
<div class="impl">
<p>The <dfn
title="dom-MessageEvent-initMessageEvent"><code>initMessageEvent()</code></dfn>
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. <a
href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p>The <dfn
title="dom-MessageEvent-data"><code>data</code></dfn>
attribute represents the message being sent.</p>
<p>The <dfn
title="dom-MessageEvent-origin"><code>origin</code></dfn> attribute
represents, in <span>server-sent events</span> and
<span>cross-document messaging</span>, the <span>origin</span> of
the document that sent the message (typically the scheme, hostname,
and port of the document, but not its path or fragment
identifier).</p>
<p>The <dfn
title="dom-MessageEvent-lastEventId"><code>lastEventId</code></dfn>
attribute represents, in <span>server-sent events</span>, the <span
title="concept-event-stream-last-event-id">last event ID
string</span> of the event source.</p>
<p>The <dfn
title="dom-MessageEvent-source"><code>source</code></dfn> attribute
represents, in <span>cross-document messaging</span>, the
<code>WindowProxy</code> of the <span>browsing context</span> of the
<code>Window</code> object from which the message came.</p>
<p>The <dfn
title="dom-MessageEvent-ports"><code>ports</code></dfn>
attribute represents, in <span>cross-document messaging</span> and
<span>channel messaging</span> the <code>MessagePortArray</code>
being sent, if any.</p>
<p>Except where otherwise specified, when the user agent creates and
dispatches a <code title="event-message">message</code> event in the
algorithms described in the following sections, the <code
title="dom-MessageEvent-lastEventId">lastEventId</code> attribute
must be the empty string, the <code
title="dom-MessageEvent-origin">origin</code> attribute must be the
empty string, the <code
title="dom-MessageEvent-source">source</code> attribute must be
null, and the <code title="dom-MessageEvent-ports">ports</code>
attribute must be null.</p>
</div>
<h3 id="server-sent-events"><dfn>Server-sent events</dfn></h3> <!--START eventsource--><!--END html--><!--END html5-->
<h4 id="server-sent-events-intro">Introduction</h4>
<p><i>This section is non-normative.</i></p>
<p>To enable servers to push data to Web pages over HTTP or using
dedicated server-push protocols, this specification introduces the
<code>EventSource</code> interface.</p>
<p>Using this API consists of creating an <code>EventSource</code>
object and registering an event listener.</p>
<pre>var source = new EventSource('updates.cgi');
source.onmessage = function (event) {
alert(event.data);
};</pre>
<p>On the server-side, the script ("<code
title="">updates.cgi</code>" in this case) sends messages in the
following form, with the <code>text/event-stream</code> MIME
type:</p>
<pre>data: This is the first message.
data: This is the second message, it
data: has two lines.
data: This is the third message.</pre>
<p>Using this API rather than emulating it using
<code>XMLHttpRequest</code> or an <code>iframe</code> allows the
user agent to make better use of network resources in cases where
the user agent implementor and the network operator are able to
coordinate in advance. Amongst other benefits, this can result in
significant savings in battery life on portable devices. This is
discussed further in the section below on <a
href="#eventsource-push">connectionless push</a>.</p>
<!--END complete-->
<!--BOILERPLATE middle-w3c-api-intro-->
<!--START complete-->
<h4>The <code>EventSource</code> interface</h4>
<pre class="idl">[<span title="dom-EventSource">Constructor</span>(in DOMString url)]
interface <dfn>EventSource</dfn> {
readonly attribute DOMString <span title="dom-EventSource-URL">URL</span>;
// ready state
const unsigned short <span title="dom-EventSource-CONNECTING">CONNECTING</span> = 0;
const unsigned short <span title="dom-EventSource-OPEN">OPEN</span> = 1;
const unsigned short <span title="dom-EventSource-CLOSED">CLOSED</span> = 2;
readonly attribute unsigned short <span title="dom-EventSource-readyState">readyState</span>;
// networking
attribute <span>Function</span> <span title="handler-EventSource-onopen">onopen</span>;
attribute <span>Function</span> <span title="handler-EventSource-onmessage">onmessage</span>;
attribute <span>Function</span> <span title="handler-EventSource-onerror">onerror</span>;
void <span title="dom-EventSource-close">close</span>();
};
<span>EventSource</span> implements <span>EventTarget</span>;</pre>
<p>The <dfn title="dom-EventSource"><code>EventSource(<var
title="">url</var>)</code></dfn> constructor takes one argument,
<var title="">url</var>, which specifies the <span>URL</span> to
which to connect. When the <code>EventSource()</code> constructor is
invoked, the UA must run these steps:</p>
<ol>
<li><p><span title="resolve a url">Resolve</span> the
<span>URL</span> specified in <var title="">url</var>, relative to
the <span>first script</span>'s <span title="script's base
URL">base URL</span>.</p></li>
<li><p>If the previous step failed, then throw a
<code>SYNTAX_ERR</code> exception.</p></li>
<li><p>Return a new <code>EventSource</code> object, and continue
these steps in the background (without blocking scripts).</p></li>
<li>
<p><span>Fetch</span> the resource identified by the resulting
<span>absolute URL</span>, from the <span>first script</span>'s
<span>origin</span>, and process it as described below.</p> <!--
not http-origin privacy sensitive -->
<p class="note">The definition of the <span
title="fetch">fetching</span> algorithm is such that if the
browser is already fetching the resource identified by the given
<span>absolute URL</span>, that connection can be reused, instead
of a new connection being established. All messages received up to
this point are dispatched immediately, in this case.</p>
</li>
</ol>
<p>This constructor must be visible when the <span>script's global
object</span> is either a <code>Window</code> object or an object
implementing the <code>WorkerUtils</code> interface.</p>
<hr>
<p>The <dfn title="dom-EventSource-URL"><code>URL</code></dfn>
attribute must return the <span>absolute URL</span> that resulted
from <span title="resolve a url">resolving</span> the value that was
passed to the constructor.</p> <!-- not the result of redirects,
since that would introduce race conditions -->
<p>The <dfn
title="dom-EventSource-readyState"><code>readyState</code></dfn>
attribute represents the state of the connection. It can have the
following values:</p>
<dl>
<dt><dfn title="dom-EventSource-CONNECTING"><code>CONNECTING</code></dfn> (numeric value 0)</dt>
<dd>The connection has not yet been established, or it was closed
and the user agent is reconnecting.</dd>
<dt><dfn title="dom-EventSource-OPEN"><code>OPEN</code></dfn> (numeric value 1)</dt>
<dd>The user agent has an open connection and is dispatching events
as it receives them.</dd>
<dt><dfn title="dom-EventSource-CLOSED"><code>CLOSED</code></dfn> (numeric value 2)</dt>
<dd>The connection is not open, and the user agent is not trying to
reconnect. Either there was a fatal error or the <code
title="dom-EventSource-close">close()</code> method was
invoked.</dd>
</dl>
<p>When the object is created its <code
title="dom-EventSource-readyState">readyState</code> must be set to
<code title="dom-EventSource-CONNECTING">CONNECTING</code> (0). The
rules given below for handling the connection define when the value
changes.</p>
<p>The <dfn title="dom-EventSource-close"><code>close()</code></dfn>
method must close the connection, if any; must abort any
reconnection attempt, if any; and must set the <code
title="dom-EventSource-readyState">readyState</code> attribute to
<code title="dom-EventSource-CLOSED">CLOSED</code>. If the
connection is already closed, the method must do nothing.</p>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as IDL attributes, by
all objects implementing the <code>EventSource</code> interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-EventSource-onopen"><code>onopen</code></dfn> <td> <code title="event-open">open</code>
<tr><td><dfn title="handler-EventSource-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
<tr><td><dfn title="handler-EventSource-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
</table>
<hr>
<p>In addition to the above, each <code>EventSource</code> object
has the following associated with it:</p>
<ul>
<li>A <dfn
title="concept-event-stream-reconnection-time">reconnection
time</dfn>, in milliseconds. This must initially be a
user-agent-defined value, probably in the region of a few
seconds.</li>
<li>A <dfn title="concept-event-stream-last-event-id">last event
ID string</dfn>. This must initially be the empty string.</li>
</ul>
<p>These values are not currently exposed on the interface.</p>
<h4>Processing model</h4>
<p>The resource indicated in the argument to the <code
title="dom-EventSource">EventSource</code> constructor is <span
title="fetch">fetched</span> when the constructor is run.</p>
<p>For HTTP connections, the <code title="">Accept</code> header may
be included; if included, it must contain only formats of event
framing that are supported by the user agent (one of which must be
<code>text/event-stream</code>, as described below).</p>
<p>If the event source's last event ID string is not the empty
string, then a <code title="http-last-event-id">Last-Event-ID</code>
HTTP header must be included with the request, whose value is the
value of the event source's last event ID string.</p>
<p>User agents should use the <code>Cache-Control: no-cache</code>
header in requests to bypass any caches for requests of event
sources. User agents should ignore HTTP cache headers in the
response, never caching event sources.</p>
<p>User agents must act as if the connection had failed due to a
network error if the <span>origin</span> of the <span>URL</span> of
the resource to be <span title="fetch">fetched</span> is not the
<span>same origin</span> as that of the <span>first script</span>
when the <code title="dom-EventSource">EventSource()</code>
constructor is invoked.</p>
<!-- v2: add CORS support -->
<hr>
<p>As data is received, the <span title="concept-task">tasks</span>
queued by the <span>networking task source</span> to handle the data
must act as follows.</p>
<p>HTTP 200 OK responses with a <span>Content-Type</span> header
specifying the type <code>text/event-stream</code> must be processed
line by line <a href="#event-stream-interpretation">as described
below</a>.</p>
<p>When a successful response with a supported <span>MIME type</span> is
received, such that the user agent begins parsing the contents of
the stream, the user agent must <span>announce the
connection</span>.</p>
<p>The <span title="concept-task">task</span> that the
<span>networking task source</span> places on the <span>task
queue</span> once the <span title="fetch">fetching algorithm</span>
for such a resource (with the correct <span>MIME type</span>) has
completed must <span>reestablish the connection</span>. This applies
whether the connection is closed gracefully or unexpectedly. It
doesn't apply for the error conditions listed below.</p>
<p>HTTP 200 OK responses that have a <span>Content-Type</span> other
than <code>text/event-stream</code> (or some other supported type)
must cause the user agent to <span>fail the connection</span>.</p>
<p>HTTP 204 No Content, and 205 Reset Content responses are
equivalent to 200 OK responses with the right <span>MIME type</span> but no
content, and thus must <span>reestablish the connection</span>.</p>
<p>Other HTTP response codes in the 2xx range <!--201 Created, 202
Accepted, 203 Non-Authoritative Information, and 206 Partial
Content-->must similarly <span>reestablish the connection</span>. They
are, however, likely to indicate an error has occurred somewhere and
may cause the user agent to emit a warning.</p>
<p>HTTP 301 Moved Permanently responses must cause the user agent to
reconnect using the new server specified URL instead of the
previously specified URL for all subsequent requests for this event
source. (It doesn't affect other <code>EventSource</code> objects
with the same URL unless they also receive 301 responses, and it
doesn't affect future sessions, e.g. if the page is reloaded.)</p>
<p>HTTP 302 Found, 303 See Other, and 307 Temporary Redirect
responses must cause the user agent to connect to the new
server-specified URL, but if the user agent needs to again request
the resource at a later point, it must return to the previously
specified URL for this event source.</p>
<p class="note">The Origin specification also introduces some
relevant requirements when dealing with redirects. <a
href="#refsORIGIN">[ORIGIN]</a></p>
<p>HTTP 305 Use Proxy, HTTP 401 Unauthorized, and 407 Proxy
Authentication Required should be treated transparently as for any
other subresource.</p>
<p>Any other HTTP response code not listed here, and any network
error that prevents the HTTP connection from being established in
the first place (e.g. DNS errors), must cause the user agent to
<span>fail the connection</span>.</p> <!-- including: HTTP 300
Multiple Choices, HTTP 304 Not Modified, HTTP 400 Bad Request, 403
Forbidden, 404 Not Found, 405 Method Not Allowed, 406 Not
Acceptable, 408 Request Timeout, 409 Conflict, 410 Gone, 411 Length
Required, 412 Precondition Failed, 413 Request Entity Too Large, 414
Request-URI Too Long, 415 Unsupported Media Type, 416 Requested
Range Not Satisfiable, 417 Expectation Failed, 500 Internal Server
Error, 501 Not Implemented, 502 Bad Gateway, 503 Service
Unavailable, 504 Gateway Timeout, and 505 HTTP Version Not Supported
responses -->
<p>For non-HTTP protocols, UAs should act in equivalent ways.</p>
<hr>
<p>When a user agent is to <dfn>announce the connection</dfn>, the
user agent must set the <code
title="dom-EventSource-readyState">readyState</code> attribute to
<code title="dom-EventSource-OPEN">OPEN</code> and <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-open">open</code> at the
<code>EventSource</code> object.</p>
<p>When a user agent is to <dfn>reestablish the connection</dfn>, the user
agent must set the <code
title="dom-EventSource-readyState">readyState</code> attribute to
<code title="dom-EventSource-CONNECTING">CONNECTING</code>,
<span>queue a task</span> to <span>fire a simple event</span> named
<code title="event-error">error</code> at the
<code>EventSource</code> object, and then <span>fetch</span> the
event source resource again after a delay equal to the reconnection
time of the event source, from the same <span>origin</span> as the
original request triggered by the <code
title="dom-EventSource">EventSource()</code>
constructor. <strong>Only if the user agent <span title="reestablish the
connection">reestablishes the connection</span> does the connection get
opened anew!</strong></p>
<p>When a user agent is to <dfn>fail the connection</dfn>, the user
agent must set the <code
title="dom-EventSource-readyState">readyState</code> attribute to
<code title="dom-EventSource-CLOSED">CLOSED</code> and <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-error">error</code> at the <code>EventSource</code>
object. <strong>Once the user agent has <span title="fail the
connection">failed the connection</span>, it does <em>not</em>
attempt to reconnect!</strong></p>
<hr>
<p>The <span>task source</span> for any <span
title="concept-task">tasks</span> that are <span title="queue a
task">queued</span> by <code>EventSource</code> objects is the
<dfn>remote event task source</dfn>.</p>
<h4>Parsing an event stream</h4>
<p>This event stream format's <span>MIME type</span> is
<code>text/event-stream</code>.</p>
<p>The event stream format is as described by the <code
title="">stream</code> production of the following ABNF, the
character set for which is Unicode. <a
href="#refsABNF">[ABNF]</a></p>
<pre>stream = [ bom ] *event
event = *( comment / field ) end-of-line
comment = colon *any-char end-of-line
field = 1*name-char [ colon [ space ] *any-char ] end-of-line
end-of-line = ( cr lf / cr / lf / eof )
eof = < matches repeatedly at the end of the stream >
; characters
lf = %x000A ; U+000A LINE FEED (LF)
cr = %x000D ; U+000D CARRIAGE RETURN (CR)
space = %x0020 ; U+0020 SPACE
colon = %x003A ; U+003A COLON (:)
bom = %xFEFF ; U+FEFF BYTE ORDER MARK
name-char = %x0000-0009 / %x000B-000C / %x000E-0039 / %x003B-10FFFF
; a Unicode character other than U+000A LINE FEED (LF), U+000D CARRIAGE RETURN (CR), or U+003A COLON (:)
any-char = %x0000-0009 / %x000B-000C / %x000E-10FFFF
; a Unicode character other than U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR)</pre>
<p>Event streams in this format must always be encoded as
UTF-8.</p>
<p>Lines must be separated by either a U+000D CARRIAGE RETURN U+000A
LINE FEED (CRLF) character pair, a single U+000A LINE FEED (LF)
character, or a single U+000D CARRIAGE RETURN (CR) character.</p>
<p>Since connections established to remote servers for such
resources are expected to be long-lived, UAs should ensure that
appropriate buffering is used. In particular, while line buffering
with lines are defined to end with a single U+000A LINE FEED (LF)
character is safe, block buffering or line buffering with different
expected line endings can cause delays in event dispatch.</p>
<h4 id="event-stream-interpretation">Interpreting an event stream</h4>
<p>Bytes or sequences of bytes that are not valid UTF-8 sequences
must be interpreted as the U+FFFD REPLACEMENT CHARACTER.</p>
<p>One leading U+FEFF BYTE ORDER MARK character must be ignored if
any are present.</p>
<p>The stream must then be parsed by reading everything line by
line, with a U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF)
character pair, a single U+000A LINE FEED (LF) character not
preceded by a U+000D CARRIAGE RETURN (CR) character, a single U+000D
CARRIAGE RETURN (CR) character not followed by a U+000A LINE FEED
(LF) character, and the end of the file being the four ways in which
a line can end.</p>
<p>When a stream is parsed, a <var title="">data</var> buffer and an
<var title="">event name</var> buffer must be associated with
it. They must be initialized to the empty string</p>
<p>Lines must be processed, in the order they are received, as
follows:</p>
<dl class="switch">
<dt>If the line is empty (a blank line)</dt>
<dd><p><a href="#dispatchMessage">Dispatch the event</a>, as
defined below.</p></dd>
<dt>If the line starts with a U+003A COLON character (:)</dt>
<dd><p>Ignore the line.</p></dd>
<dt>If the line contains a U+003A COLON character character (:)</dt>
<dd>
<p>Collect the characters on the line before the first U+003A
COLON character (:), and let <var title="">field</var> be that
string.</p>
<p>Collect the characters on the line after the first U+003A COLON
character (:), and let <var title="">value</var> be that
string. If <var title="">value</var> starts with a U+0020
SPACE character, remove it from <var title="">value</var>.</p>
<p><a href="#processField">Process the field</a> using the steps
described below, using <var title="">field</var> as the field name
and <var title="">value</var> as the field value.</p>
</dd>
<dt>Otherwise, the string is not empty but does not contain a U+003A COLON character character (:)</dt>
<dd>
<p><a href="#processField">Process the field</a> using the steps
described below, using the whole line as the field name, and
the empty string as the field value.</p>
</dd>
</dl>
<p>Once the end of the file is reached, the user agent must <a
href="#dispatchMessage">dispatch the event</a> one final time, as
defined below.</p>
<p id="processField">The steps to <dfn title="">process the
field</dfn> given a field name and a field value depend on the field
name, as given in the following list. Field names must be compared
literally, with no case folding performed.</p>
<dl class="switch">
<dt>If the field name is "event"</dt>
<dd><p>Set the <var title="">event name</var> buffer to field
value.</p></dd>
<dt>If the field name is "data"</dt>
<dd><p>Append the field value to the <var title="">data</var>
buffer, then append a single U+000A LINE FEED (LF) character to the
<var title="">data</var> buffer.</p></dd>
<dt>If the field name is "id"</dt>
<dd><p>Set the event stream's <span
title="concept-event-stream-last-event-id">last event ID</span> to
the field value.</p></dd>
<dt>If the field name is "retry"</dt>
<dd><p>If the field value consists of only characters in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then interpret the
field value as an integer in base ten, and set the event stream's
<span title="concept-event-stream-reconnection-time">reconnection
time</span> to that integer. Otherwise, ignore the field.</p></dd>
<!-- v2 feature request from Per-Erik Brodin:
> > > Finally, it could be useful to be able to reset the reconnection
> > > time to the user agent default value by sending the retry field only
> > > and leave out the value similar to how you reset the last event id.
> >
> > What's the use case?
>
> Take the stock ticker as an example. When the stock market closes the
> server logic knows that there won't be any new events for a number of
> hours and so it can send the corresponding reconnection time and close
> the connection. If the client is still running by the time the market
> opens, it will reconnect, and the server can now reset the reconnection
> time to a time that is convenient for the user agent (which is the user
> agent default value, unknown to the server).
-->
<!-- v2 feature request from John Fallows - http://www.w3.org/mid/c5b3a7130810271238h11e40a4fybfcd5983ed5dc08d@mail.gmail.com
<dt>If the field name is "reconnect"</dt>
<dd><p>If the field value is the empty string, then: <a
href="#dispatchMessage">dispatch the event</a> as defined below,
and then drop the connection and immediately reconnect as if the
<span title="concept-event-stream-reconnection-time">reconnection
time</span> was zero for this one time.</p></dd>
-->
<dt>Otherwise</dt>
<dd><p>The field is ignored.</p></dd>
</dl>
<p id="dispatchMessage">When the user agent is required to <dfn
title="">dispatch the event</dfn>, then the user agent must act as
follows:
<ol>
<li><p>If the <var title="">data</var> buffer is an empty string,
set the <var title="">data</var> buffer and the <var title="">event
name</var> buffer to the empty string and abort these
steps.</p></li>
<li><p>If the <var title="">data</var> buffer's last character is a
U+000A LINE FEED (LF) character, then remove the last character
from the <var title="">data</var> buffer.</p></li>
<li><p>If the <var title="">event name</var> buffer is not the
empty string but is also not a valid event type name, as defined by
the DOM Events specification, set the <var title="">data</var>
buffer and the <var title="">event name</var> buffer to the empty
string and abort these steps. <a
href="#refsDOMEVENTS">[DOMEVENTS]</a></p></li>
<li><p>Otherwise, create an event that uses the
<code>MessageEvent</code> interface, with the event name <code
title="event-message">message</code>, which does not bubble, is not
cancelable, and has no default action. The <code
title="dom-MessageEvent-data">data</code> attribute must be set to
the value of the <var title="">data</var> buffer, the <code
title="dom-MessageEvent-origin">origin</code> attribute must be set
to the <span title="Unicode serialization of an origin">Unicode
serialization</span> of the <span>origin</span> of the event
stream's URL, and the <code
title="dom-MessageEvent-lastEventId">lastEventId</code> attribute
must be set to the <span
title="concept-event-stream-last-event-id">last event ID
string</span> of the event source.</p></li>
<li><p>If the <var title="">event name</var> buffer has a value
other than the empty string, change the type of the newly created
event to equal the value of the <var title="">event name</var>
buffer.</p></li>
<li><p>Set the <var title="">data</var> buffer and the <var
title="">event name</var> buffer to the empty string.</p></li>
<li><p><span>Queue a task</span> to dispatch the newly created
event at the <code>EventSource</code> object.</p></li>
</ol>
<p class="note">If an event doesn't have an "id" field, but an
earlier event did set the event source's <span
title="concept-event-stream-last-event-id">last event ID
string</span>, then the event's <code
title="dom-MessageEvent-lastEventId">lastEventId</code> field will
be set to the value of whatever the last seen "id" field was.</p>
<div class="example">
<p>The following event stream, once followed by a blank line:</p>
<pre>data: YHOO
data: +2
data: 10</pre>
<p>...would cause an event <code
title="event-message">message</code> with the interface
<code>MessageEvent</code> to be dispatched on the
<code>EventSource</code> object. The event's <code
title="dom-MessageEvent-data">data</code> attribute would contain
the string <code>YHOO\n+2\n10</code> (where <code>\n</code>
represents a newline).</p>
<p>This could be used as follows:
<pre>var stocks = new EventSource("http://stocks.example.com/ticker.php");
stocks.onmessage = function (event) {
var data = event.data.split('\n');
updateStocks(data[0], data[1], data[2]);
};</pre>
<p>...where <code title="">updateStocks()</code> is a function defined as:</p>
<pre>function updateStocks(symbol, delta, value) { ... }</pre>
<p>...or some such.</p>
</div>
<div class="example">
<p>The following stream contains four blocks. The first block has
just a comment, and will fire nothing. The second block has two
fields with names "data" and "id" respectively; an event will be
fired for this block, with the data "first event", and will then
set the last event ID to "1" so that if the connection died between
this block and the next, the server would be sent a <code
title="http-last-event-id">Last-Event-ID</code> header with the
value "1". The third block fires an event with data "second event",
and also has an "id" field, this time with no value, which resets
the last event ID to the empty string (meaning no <code
title="http-last-event-id">Last-Event-ID</code> header will now be
sent in the event of a reconnection being attempted). Finally, the
last block just fires an event with the data " third event"
(with a single leading space character). Note that the last block
doesn't have to end with a blank line, the end of the stream is
enough to trigger the dispatch of the last event.</p>
<pre>: test stream
data: first event
id: 1
data:second event
id
data: third event</pre>
</div>
<div class="example">
<p>The following stream fires just one event:</p>
<pre>data
data
data
data:</pre>
<p>The first and last blocks do nothing, since they do not contain
any actual data (the <var title="">data</var> buffer remains at the
empty string, and so nothing gets dispatched). The middle block
fires an event with the data set to a single newline character.</p>
</div>
<div class="example">
<p>The following stream fires two identical events:</p>
<pre>data:test
data: test</pre>
<p>This is because the space after the colon is ignored if
present.</p>
</div>
<h4>Notes</h4>
<p>Legacy proxy servers are known to, in certain cases, drop HTTP
connections after a short timeout. To protect against such proxy
servers, authors can include a comment line (one starting with a ':'
character) every 15 seconds or so.</p>
<p>Authors wishing to relate event source connections to each other
or to specific documents previously served might find that relying
on IP addresses doesn't work, as individual clients can have
multiple IP addresses (due to having multiple proxy servers) and
individual IP addresses can have multiple clients (due to sharing a
proxy server). It is better to include a unique identifier in the
document when it is served and then pass that identifier as part of
the URL when the connection is established.</p>
<p>Authors are also cautioned that HTTP chunking can have unexpected
negative effects on the reliability of this protocol. Where
possible, chunking should be disabled for serving event streams
unless the rate of messages is high enough for this not to
matter.</p> <!-- v2 can we get a better solution? -->
<p>Clients that support HTTP's per-server connection limitation
might run into trouble when opening multiple pages from a site if
each page has an <code>EventSource</code> to the same
domain. Authors can avoid this using the relatively complex
mechanism of using unique domain names per connection, or by
allowing the user to enable or disable the <code>EventSource</code>
functionality on a per-page basis, or by sharing a single
<code>EventSource</code> object using a <span
title="SharedWorkerGlobalScope">shared worker</span>.
<!--END complete-->
<a href="#refsWEBWORKERS">[WEBWORKERS]</a>
<!--START complete-->
</p>
<h4 id="eventsource-push">Connectionless push and other features</h4>
<p>User agents running in controlled environments, e.g. browsers on
mobile handsets tied to specific carriers, may offload the
management of the connection to a proxy on the network. In such a
situation, the user agent for the purposes of conformance is
considered to include both the handset software and the network
proxy.</p>
<div class="example">
<p>For example, a browser on a mobile device, after having
established a connection, might detect that it is on a supporting
network and request that a proxy server on the network take over
the management of the connection. The timeline for such a situation
might be as follows:</p>
<ol>
<li>Browser connects to a remote HTTP server and requests the
resource specified by the author in the <code
title="dom-EventSource">EventSource</code> constructor.</li>
<li>The server sends occasional messages.</li>
<li>In between two messages, the browser detects that it is idle
except for the network activity involved in keeping the TCP
connection alive, and decides to switch to sleep mode to save power.</li>
<li>The browser disconnects from the server.</li>
<li>The browser contacts a service on the network, and requests
that that service, a "push proxy", maintain the connection instead.</li>
<li>The "push proxy" service contacts the remote HTTP server and
requests the resource specified by the author in the <code
title="dom-EventSource">EventSource</code> constructor (possibly
including a <code title="http-last-event-id">Last-Event-ID</code>
HTTP header, etc).</li>
<li>The browser allows the mobile device to go to sleep.</li>
<li>The server sends another message.</li>
<li>The "push proxy" service uses a technology such as OMA push to
convey the event to the mobile device, which wakes only only
enough to process the event and then returns to sleep.</li>
</ol>
</div>
<p>This can reduce the total data usage, and can therefore result in
considerable power savings.</p>
<p>As well as implementing the existing API and
<code>text/event-stream</code> wire format as defined by this
specification and in more distributed ways as described above,
formats of event framing defined by <span>other applicable
specifications</span> may be supported. This specification does not
define how they are to be parsed or processed.</p>
<h4>Garbage collection</h4>
<p>While an <code>EventSource</code> object's <code
title="dom-EventSource-readyState">readyState</code> is not <code
title="dom-EventSource-CLOSED">CLOSED</code>, and the object has one
or more event listeners registered for <code
title="event-message">message</code> events, there must be a strong
reference from the <code>Window</code> or <code>WorkerUtils</code>
object that the <code>EventSource</code> object's constructor was
invoked from to the <code>EventSource</code> object itself.</p>
<p>If an <code>EventSource</code> object is garbage collected while
its connection is still open, the connection must be closed.</p>
<h4>IANA considerations</h4>
<h5><dfn><code>text/event-stream</code></dfn></h5>
<p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p>
<!--
To: ietf-types@iana.org
Subject: Registration of media type text/event-stream
-->
<dl>
<dt>Type name:</dt>
<dd>text</dd>
<dt>Subtype name:</dt>
<dd>event-stream</dd>
<dt>Required parameters:</dt>
<dd>No parameters</dd>
<dt>Optional parameters:</dt>
<dd>No parameters</dd>
<dt>Encoding considerations:</dt>
<dd>Always UTF-8.</dd>
<dt>Security considerations:</dt>
<dd>
<p>An event stream from an origin distinct from the origin of the
content consuming the event stream can result in information
leakage. To avoid this, user agents are required to <!--v2: apply
CORS semantics or--> block all cross-origin loads. <!--v2: <a
href="#refsCORS">[CORS]</a>--></p>
<p>Event streams can overwhelm a user agent; a user agent is
expected to apply suitable restrictions to avoid depleting local
resources because of an overabundance of information from an event
stream.</p>
<p>Servers can be overwhelmed if a situation develops in which the
server is causing clients to reconnect rapidly. Servers should use
a 5xx status code to indicate capacity problems, as this will
prevent conforming clients from reconnecting automatically.</p>
</dd>
<dt>Interoperability considerations:</dt>
<dd>
Rules for processing both conforming and non-conforming content
are defined in this specification.
</dd>
<dt>Published specification:</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Applications that use this media type:</dt>
<dd>
Web browsers and tools using Web services.
</dd>
<dt>Additional information:</dt>
<dd>
<dl>
<dt>Magic number(s):</dt>
<dd>No sequence of bytes can uniquely identify an event stream.</dd>
<dt>File extension(s):</dt>
<dd>No specific file extensions are recommended for this type.</dd>
<dt>Macintosh file type code(s):</dt>
<dd>No specific Macintosh file type codes are recommended for this type.</dd>
</dl>
</dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>This format is only expected to be used by dynamic open-ended
streams served using HTTP or a similar protocol. Finite resources
are not expected to be labeled with this type.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C</dd>
</dl>
<p>Fragment identifiers have no meaning with
<code>text/event-stream</code> resources.</p>
<h5><dfn title="http-last-event-id"><code>Last-Event-ID</code></dfn></h5>
<p>This section describes a header field for registration in the
Permanent Message Header Field Registry. <a
href="#refsRFC3864">[RFC3864]</a></p>
<dl>
<dt>Header field name</dt>
<dd>Last-Event-ID</dd>
<dt>Applicable protocol</dt>
<dd>http</dd>
<dt>Status</dt>
<dd>standard</dd>
<dt>Author/Change controller</dt>
<dd>W3C</dd>
<dt>Specification document(s)</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Related information</dt>
<dd>None.</dd>
</dl>
<!--END eventsource--><!--START html--><!--START html5-->
<h3 id="network"><dfn>Web sockets</dfn></h3> <!--START websocket--><!--START websocket-api--><!--END html--><!--END html5-->
<h4 id="network-intro">Introduction</h4>
<p><i>This section is non-normative.</i></p>
<p>To enable Web applications to maintain bidirectional
communications with server-side processes, this specification
introduces the <code>WebSocket</code> interface.</p>
<p class="note">This interface does not allow for raw access to the
underlying network. For example, this interface could not be used to
implement an IRC client without proxying messages through a custom
server.</p>
<!--END complete-->
<!--BOILERPLATE middle-w3c-api-intro-->
<!--START complete-->
<h4>The <code>WebSocket</code> interface</h4>
<pre class="idl">[<span title="dom-WebSocket">Constructor</span>(in DOMString url, in optional DOMString protocol)]
interface <dfn>WebSocket</dfn> {
readonly attribute DOMString <span title="dom-WebSocket-URL">URL</span>;
// ready state
const unsigned short <span title="dom-WebSocket-CONNECTING">CONNECTING</span> = 0;
const unsigned short <span title="dom-WebSocket-OPEN">OPEN</span> = 1;
const unsigned short <span title="dom-WebSocket-CLOSED">CLOSED</span> = 2;
readonly attribute unsigned short <span title="dom-WebSocket-readyState">readyState</span>;
readonly attribute unsigned long <span title="dom-WebSocket-bufferedAmount">bufferedAmount</span>;
// networking
attribute <span>Function</span> <span title="handler-WebSocket-onopen">onopen</span>;
attribute <span>Function</span> <span title="handler-WebSocket-onmessage">onmessage</span>;
attribute <span>Function</span> <span title="handler-WebSocket-onclose">onclose</span>;
boolean <span title="dom-WebSocket-send">send</span>(in DOMString data);
void <span title="dom-WebSocket-close">close</span>();
};
<span>WebSocket</span> implements <span>EventTarget</span>;</pre>
<p>The <dfn title="dom-WebSocket"><code>WebSocket(<var
title="">url</var>, <var title="">protocol</var>)</code></dfn>
constructor takes one or two arguments. The first argument, <var
title="">url</var>, specifies the <span>URL</span> to which to
connect. The second, <var title="">protocol</var>, if present,
specifies a sub-protocol that the server must support for the
connection to be successful. The sub-protocol name must be a
non-empty ASCII string with no control characters in it (i.e. only
characters in the range U+0020 to U+007E).</p>
<p>When the <code>WebSocket()</code> constructor is invoked, the UA
must run these steps:</p>
<ol>
<!-- beware, this is very similar to the steps for what happens
during a redirect, in the protocol section -->
<li><p><span>Parse a Web Socket URL's components</span> from the
<var title="">url</var> argument, to obtain <var
title="">host</var>, <var title="">port</var>, <var
title="">resource name</var>, and <var title="">secure</var>. If
this fails, throw a <code>SYNTAX_ERR</code> exception and abort
these steps.</p></li>
<li><p>If <var title="">port</var> is a port to which the user
agent is configured to block access, then throw a
<code>SECURITY_ERR</code> exception. (User agents typically block
access to well-known ports like SMTP.)</p></li>
<!--
e.g. http://www.mozilla.org/projects/netlib/PortBanning.html
-->
<li><p>If <var title="">protocol</var> is present but is either the
empty string or contains characters with Unicode code points less
than U+0020 or greater than U+007E (i.e. any characters that are
not printable ASCII characters), then throw a
<code>SYNTAX_ERR</code> exception and abort these steps.</p></li>
<li><p>Let <var title="">origin</var> be the <span title="ASCII
serialization of an origin">ASCII serialization</span> of the
<span>origin</span> of the script that invoked the <code
title="dom-WebSocket">WebSocket()</code> constructor,
<span>converted to ASCII lowercase</span>.</p></li>
<li><p>Return a new <code>WebSocket</code> object, and continue
these steps in the background (without blocking scripts).</p></li>
<li>
<p><span>Establish a Web Socket connection</span> to a host <var
title="">host</var>, on port <var title="">port</var> (if one was
specified), from <var title="">origin</var>, with the flag <var
title="">secure</var>, with <var title="">resource name</var> as
the resource name, and with <var title="">protocol</var> as the
protocol (if it is present).</p>
<p class="note">If the "<span>establish a Web Socket
connection</span>" algorithm fails, it triggers the "<span>fail
the Web Socket connection</span>" algorithm, which then invokes
the "<span>close the Web Socket connection</span>" algorithm,
which then establishes that the "<span>Web Socket connection is
closed</span>", which fires the <code
title="event-close">close</code> event <a
href="#closeWebSocket">as described below</a>.</p>
</li>
</ol>
<p>This constructor must be visible when the <span>script's global
object</span> is either a <code>Window</code> object or an object
implementing the <code>WorkerUtils</code> interface.</p>
<hr>
<p>The <dfn title="dom-WebSocket-URL"><code>URL</code></dfn>
attribute must return the result of <span title="resolve a
url">resolving</span> the <span>URL</span> that was passed to the
constructor. (It doesn't matter what it is resolved relative to,
since we already know it is an <span>absolute URL</span>.)</p>
<p>The <dfn
title="dom-WebSocket-readyState"><code>readyState</code></dfn>
attribute represents the state of the connection. It can have the
following values:</p>
<dl>
<dt><dfn title="dom-WebSocket-CONNECTING"><code>CONNECTING</code></dfn> (numeric value 0)</dt>
<dd>The connection has not yet been established.</dd>
<dt><dfn title="dom-WebSocket-OPEN"><code>OPEN</code></dfn> (numeric value 1)</dt>
<dd>The <span>Web Socket connection is established</span> and communication is possible.</dd>
<dt><dfn title="dom-WebSocket-CLOSED"><code>CLOSED</code></dfn> (numeric value 2)</dt>
<dd>The connection has been closed or could not be opened.</dd>
</dl>
<p>When the object is created its <code
title="dom-WebSocket-readyState">readyState</code> must be set to
<code title="dom-WebSocket-CONNECTING">CONNECTING</code> (0).</p>
<p>The <dfn title="dom-WebSocket-send"><code>send(<var
title="">data</var>)</code></dfn> method transmits data using the
connection. If the <code
title="dom-WebSocket-readyState">readyState</code> attribute is
<code title="dom-WebSocket-CONNECTING">CONNECTING</code>, it must
raise an <code>INVALID_STATE_ERR</code> exception. If the <var
title="">data</var> argument has any unpaired surrogates, then it
must raise <code>SYNTAX_ERR</code>. If the connection is
established, and the string has no unpaired surrogates, then the
user agent must <span>send <var title="">data</var> using the Web
Socket</span>. If the data cannot be sent, e.g. because it would
need to be buffered but the buffer is full, the user agent must
<span>close the Web Socket connection</span>. The method must then
return true if the connection is still established (and the data was
queued or sent successfully), or false if the connection is closed
(e.g. because the user agent just had a buffer overflow and failed
to send the data).</p>
<p>The <dfn title="dom-WebSocket-close"><code>close()</code></dfn>
method must <span>close the Web Socket connection</span> or
connection attempt, if any, and change the <code
title="dom-WebSocket-readyState">readyState</code> attribute's value
to <code title="dom-WebSocket-CLOSED">CLOSED</code> (2). If the
connection is already closed, it must do nothing.</p>
<p class="note">Closing the connection immediately causes a task to
be queued to fire a <code title="event-close">close</code> event, as
<a href="#closeWebSocket">described below</a>.</p>
<hr>
<p>The <dfn
title="dom-WebSocket-bufferedAmount"><code>bufferedAmount</code></dfn>
attribute must return the number of bytes that have been queued but
not yet sent. If the connection is closed, this attribute's value
will only increase with each call to the <code
title="dom-WebSocket-send">send()</code> method (the number does not
reset to zero once the connection closes).</p>
<hr>
<p>The following are the <span>event handlers</span> that must be
supported, as IDL attributes, by all objects implementing the
<code>WebSocket</code> interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-WebSocket-onopen"><code>onopen</code></dfn> <td> <code title="event-open">open</code>
<tr><td><dfn title="handler-WebSocket-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
<tr><td><dfn title="handler-WebSocket-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code>
</table>
<h4>Feedback from the protocol</h4>
<p>When the <i>Web Socket connection is established</i>, the user
agent must <span>queue a task</span> to first change the <code
title="dom-WebSocket-readyState">readyState</code> attribute's value
to <code title="dom-WebSocket-OPEN">OPEN</code> (1), and then
<span>fire a simple event</span> named <code
title="event-open">open</code> at the <code>WebSocket</code>
object.</p>
<p>When <i>a Web Socket message has been received</i> with text <var
title="">data</var>, the user agent must create an event that uses
the <code>MessageEvent</code> interface, with the event name <code
title="event-message">message</code>, which does not bubble, is not
cancelable, has no default action, and whose <code
title="dom-MessageEvent-data">data</code> attribute is set to <var
title="">data</var>, and <span>queue a task</span> to check to see
if the <code title="dom-WebSocket-readyState">readyState</code>
attribute's value is <code title="dom-WebSocket-OPEN">OPEN</code>
(1), and if so, dispatch the event at the <code>WebSocket</code>
object.</p>
<p id="closeWebSocket">When the <i>Web Socket connection is
closed</i>, the user agent must <span>queue a task</span> to first
change the <code title="dom-WebSocket-readyState">readyState</code>
attribute's value to <code
title="dom-WebSocket-CLOSED">CLOSED</code> (2), and then <span>fire
a simple event</span> named <code title="event-close">close</code>
at the <code>WebSocket</code> object. (If the <code
title="dom-WebSocket-close">close()</code> method was called, the
<code title="dom-WebSocket-readyState">readyState</code> attribute's
value will already be set to <code
title="dom-WebSocket-CLOSED">CLOSED</code> (2) when this task
runs.)</p>
<p>The <span>task source</span> for all <span
title="concept-task">tasks</span> <span title="queue a
task">queued</span> in this section is the <dfn>Web Socket task
source</dfn>.</p>
<h5>Garbage collection</h5>
<p>A <code>WebSocket</code> object with an open connection must not
be garbage collected if there are any event listeners registered for
<code title="event-message">message</code> events.</p>
<p>If a <code>WebSocket</code> object is garbage collected while its
connection is still open, the user agent must <span>close the Web
Socket connection</span>.</p>
<!--END websocket-api-->
<!--START websocket-protocol-->
<h4 id="websocket-protocol" title="The Web Socket protocol enables
two-way communication between a user agent running untrusted code
running in a controlled environment to a remote host that has
opted-in to communications from that code. The security model used
for this is the Origin-based security model commonly used by Web
browsers. The protocol consists of an initial handshake followed by
basic message framing, layered over TCP. The goal of this technology
is to provide a mechanism for browser-based applications that need
two-way communication with servers that does not rely on opening
multiple HTTP connections (e.g. using XMLHttpRequest or
<iframe>s and long polling).">The Web Socket protocol</h4>
<h5>Introduction</h5>
<h6>Background</h6>
<p><i>This section is non-normative.</i></p>
<p>Historically, creating an instant messenger chat client as a Web
application has required an abuse of HTTP to poll the server for
updates while sending upstream notifications as distinct HTTP
calls.</p>
<p>This results in a variety of problems:</p>
<ul>
<li>The server is forced to use a number of different underlying
TCP connections for each client: one for sending information to the
client, and a new one for each incoming message.</li>
<li>The wire protocol has a high overhead, with each
client-to-server message having an HTTP header.</li>
<li>The client-side script is forced to maintain a mapping from the
outgoing connections to the incoming connection to track
replies.</li>
</ul>
<p>A simpler solution would be to use a single TCP connection for
traffic in both directions. This is what the Web Socket protocol
provides. Combined with the Web Socket API, it provides an
alternative to HTTP polling for two-way communication from a Web
page to a remote server.
<!--END complete-->
<a href="#refsWSAPI">[WSAPI]</a>
<!--START complete-->
</p>
<p>The same technique can be used for a variety of Web applications:
games, stock tickers, multiuser applications with simultaneous
editing, user interfaces exposing server-side services in real time,
etc.</p>
<h6>Protocol overview</h6>
<p><i>This section is non-normative.</i></p>
<p>The protocol has two parts: a handshake, and then the data
transfer.</p>
<p>The handshake from the client looks as follows:</p>
<pre>GET /demo HTTP/1.1
Upgrade: WebSocket
Connection: Upgrade
Host: example.com
Origin: http://example.com
WebSocket-Protocol: sample</pre>
<p>The handshake from the server looks as follows:</p>
<pre>HTTP/1.1 101 Web Socket Protocol Handshake
Upgrade: WebSocket
Connection: Upgrade
WebSocket-Origin: http://example.com
WebSocket-Location: ws://example.com/demo
WebSocket-Protocol: sample</pre>
<p>The first three lines in each case are hard-coded (the exact case
and order matters); the remainder are an unordered <span>ASCII
case-insensitive</span> set of fields, one per line, that match the
following non-normative ABNF:
<!--END complete-->
<a href="#refsRFC5234">[RFC5234]</a>
<!--START complete--><!--END websocket-protocol-->
<a href="#refsABNF">[ABNF]</a>
<!--START websocket-protocol-->
</p>
<pre>field = 1*name-char colon [ space ] *any-char cr lf
colon = %x003A ; U+003A COLON (:)
space = %x0020 ; U+0020 SPACE
cr = %x000D ; U+000D CARRIAGE RETURN (CR)
lf = %x000A ; U+000A LINE FEED (LF)
name-char = %x0000-0009 / %x000B-000C / %x000E-0039 / %x003B-10FFFF
; a Unicode character other than U+000A LINE FEED (LF), U+000D CARRIAGE RETURN (CR), or U+003A COLON (:)
any-char = %x0000-0009 / %x000B-000C / %x000E-10FFFF
; a Unicode character other than U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR)</pre>
<p>Lines that don't match the above production cause the connection
to be aborted.</p>
<p class="note">The character set for the above ABNF is Unicode. The
headers themselves are encoded as UTF-8.</p>
<p>Once the client and server have both sent their handshakes, and
if the handshake was successful, then the data transfer part
starts. This is a two-way communication channel where each side can,
independently from the other, send data at will.</p>
<p>Data is sent in the form of UTF-8 text. Each frame of data starts
with a 0x00 byte and ends with a 0xFF byte, with the UTF-8 text in
between.</p>
<p>The Web Socket protocol uses this framing so that specifications
that use the Web Socket protocol can expose such connections using
an event-based mechanism instead of requiring users of those
specifications to implement buffering and piecing together of
messages manually.</p>
<hr>
<p>The protocol is designed to support other frame types in
future. Instead of the 0x00 byte, other bytes might in future be
defined. Frames denoted by bytes that do not have the high bit set
(0x00 to 0x7F) are treated as described above (a stream of bytes
terminated by 0xFF). Frames denoted by bytes that have the high bit
set (0x80 to 0xFF) have a leading length indicator, which is encoded
as a series of 7-bit bytes stored in octets with the 8th bit being
set for all but the last byte. The remainder of the frame is then as
much data as was specified.</p>
<hr>
<p>The following diagrams summarise the protocol:</p>
<pre>Handshake
|
\|/
Frame type byte <-------------------------------------.
| | |
| `-- (0x00 to 0x7F) --> Data... --> 0xFF -->-+
| |
`-- (0x80 to 0xFF) --> Length --> Data... ------->-'</pre>
<h6>Design philosophy</h6>
<p><i>This section is non-normative.</i></p>
<p>The Web Socket protocol is designed on the principle that there
should be minimal framing (the only framing that exists is to make
the protocol frame-based instead of stream-based, and to support a
distinction between Unicode text and binary frames). It is expected
that metadata would be layered on top of Web Socket by the
application layer, in the same way that metadata is layered on top
of TCP/IP by the application layer (HTTP).</p>
<p>Conceptually, Web Socket is really just a layer on top of TCP/IP
that adds a Web "origin"-based security model for browsers; adds an
addressing and protocol naming mechanism to support multiple
services on one port and multiple host names on one IP address; and
layers a framing mechanism on top of TCP to get back to the IP
packet mechanism that TCP is built on, but without length
limits. Other than that, it adds nothing. Basically it is intended
to be as close as possible to just exposing raw TCP/IP to script as
possible given the constraints of the Web. It's also designed in
such a way that its servers can share a port with HTTP servers, by
having its handshake be a valid HTTP Upgrade handshake also.</p>
<h6>Security model</h6>
<p><i>This section is non-normative.</i></p>
<p>The Web Socket protocol uses the origin model used by Web
browsers to restrict which Web pages can contact a Web Socket server
when the Web Socket protocol is used from a Web page. Naturally,
when the Web Socket protocol is used directly (not from a Web page),
the origin model is not useful, as the client can provide any
arbitrary origin string.</p>
<p>This protocol is intended to fail to establish a connection with
servers of pre-existing protocols like SMTP or HTTP, while allowing
HTTP servers to opt-in to supporting this protocol if desired. This
is achieved by having a strict and elaborate handshake, and by
limiting the data that can be inserted into the connection before
the handshake is finished (thus limiting how much the server can be
influenced).</p>
<h6>Relationship to TCP/IP and HTTP</h6>
<p><i>This section is non-normative.</i></p>
<p>The Web Socket protocol is an independent TCP-based protocol. Its
only relationship to HTTP is that its handshake is interpreted by
HTTP servers as an Upgrade request.</p>
<p>Based on the expert recommendation of the IANA<!-- [IANA #257455]
-->, the Web Socket protocol by default uses port 80 for regular Web
Socket connections and port 443 for Web Socket connections tunneled
over TLS.</p>
<h6>Establishing a connection</h6>
<p><i>This section is non-normative.</i></p>
<p>There are several options for establishing a Web Socket connection.</p>
<p>On the face of it, the simplest method would seem to be to use
port 80 to get a direct connection to a Web Socket server. Port 80
traffic, however, will often be intercepted by HTTP proxies, which
can lead to the connection failing to be established.</p>
<p>The most reliable method, therefore, is to use TLS encryption and
port 443 to connect directly to a Web Socket server. This has the
advantage of being more secure; however, TLS encryption can be
computationally expensive.</p>
<p>When a connection is to be made to a port that is shared by an
HTTP server (a situation that is quite likely to occur with traffic
to ports 80 and 443), the connection will appear to the HTTP server
to be a regular GET request with an Upgrade offer. In relatively
simple setups with just one IP address and a single server for all
traffic to a single hostname, this might allow a practical way for
systems based on the Web Socket protocol to be deployed. In more
elaborate setups (e.g. with load balancers and multiple servers), a
dedicated set of hosts for Web Socket connections separate from the
HTTP servers is probably easier to manage.</p>
<h6>Writing a simple Web Socket server</h6>
<p><i>This section is non-normative.</i></p>
<p>If the Web Socket protocol is being used to provide a feature for
a specific site, then the handshake can be hard-coded, and the data
provided by the client in the handshake can be safely ignored. This
section describes an implementation strategy for this case.</p>
<p>Listen on a port for TCP/IP. Upon receiving a connection request,
open a connection and send the following bytes back to the
client:</p>
<pre>48 54 54 50 2F 31 2E 31 20 31 30 31 20 57 65 62
20 53 6F 63 6B 65 74 20 50 72 6F 74 6F 63 6F 6C
20 48 61 6E 64 73 68 61 6B 65 0D 0A 55 70 67 72
61 64 65 3A 20 57 65 62 53 6F 63 6B 65 74 0D 0A
43 6F 6E 6E 65 63 74 69 6F 6E 3A 20 55 70 67 72
61 64 65 0D 0A 57 65 62 53 6F 63 6B 65 74 2D 4F
72 69 67 69 6E 3A 20</pre>
<p>Send the <span title="ASCII serialization of an origin">ASCII
serialization</span> of the origin from which the server is willing
to accept connections. <a href="#refsORIGIN">[ORIGIN]</a></p>
<div class="example">
<p>For example: <code title="">http://example.com</code></p>
</div>
<p>Continue by sending the following bytes back to the client:</p>
<pre>0D 0A 57 65 62 53 6F 63 6B 65 74 2D 4C 6F 63 61
74 69 6F 6E 3A 20</pre>
<p>Send the <span>URL</span> of the Web Socket script.</p>
<div class="example">
<p>For example: <code title="">ws://example.com/demo</code></p>
</div>
<p>Finish the handshake by sending the four bytes 0x0D 0x0A 0x0D
0x0A to the client. Then, read data <em>from</em> the client until
four bytes 0x0D 0x0A 0x0D 0x0A are read.</p>
<p class="note">User agents will drop the connection after the
handshake if the origin and URL sent as part of the algorithm above
don't match what the client sent to the server, to protect the
server from third-party scripts. This is why the server has to send
these strings: to confirm which origins and URLs the server is
willing to service.</p>
<p>At this point, there are two concerns: receiving frames and
sending frames.</p>
<p>To receive a frame, read a byte, verify that it is a 0x00 byte,
then read bytes until you find a 0xFF byte, and interpret all the
bytes between the 0x00 and 0xFF bytes as a UTF-8 string (the frame
payload, or message). This process can be repeated as necessary. If
at any point the first byte of one of these sequences is not 0x00,
then an error has occurred, and closing the connection is the
appropriate response.</p>
<p>To send a frame, first send a 0x00 byte, then send the message as
a UTF-8 string, then send a 0xFF byte. Again, this process can be
repeated as necessary.</p>
<p>The connection can be closed as desired.</p>
<h6>Subprotocols using the Web Socket protocol</h6>
<p><i>This section is non-normative.</i></p>
<p>The client can request that the server use a specific subprotocol
by including the <code
title="http-websocket-protocol">Websocket-Protocol</code> header in
its handshake. If it is specified, the server needs to include the
same header and value in its response for the connection to be
established.</p>
<p>These subprotocol names do not need to be registered, but if a
subprotocol is intended to be implemented by multiple independent
Web Socket servers, potential clashes with the names of subprotocols
defined independently can be avoided by using names that contain the
domain name of the subprotocol's originator. For example, if Example
Corporation were to create a Chat subprotocol to be implemented by
many servers around the Web, they could name it
"chat.example.com". If the Example Organisation called their
competing subprotocol "example.org's chat protocol", then
the two subprotocols could be implemented by servers simultaneously,
with the server dynamically selecting which subprotocol to use based
on the value sent by the client.</p>
<p>Subprotocols can be versioned in backwards-incompatible ways by
changing the subprotocol name, eg. going from "bookings.example.net"
to "bookings.example.net2". These subprotocols would be considered
completely separate by Web Socket clients. Backwards-compatible
versioning can be implemented by reusing the same subprotocol string
but carefully designing the actual subprotocol to support this kind
of extensibility.</p>
<!--END complete-->
<!--BOILERPLATE middle-ietf-conformance-->
<h6>Terminology</h6>
<p><dfn title="converted to ASCII lowercase">Converting a string to
ASCII lowercase</dfn> means replacing all characters in the range
U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL
LETTER Z) with the corresponding characters in the range U+0061
to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z).</p>
<p>The term "URL" is used in this section in a manner consistent
with the terminology used in HTML, namely, to denote a string that
might or might not be a valid URI or IRI and to which certain error
handling behaviors will be applied when the string is parsed. <a
href="#refsHTML5">[HTML5]</a></p>
<!--START complete-->
<h5>Web Socket URLs</h5>
<h6>Parsing Web Socket URLs</h6>
<p>The steps to <dfn>parse a Web Socket URL's components</dfn> from
a string <var title="">url</var> are as follows. These steps return
either a <var title="">host</var>, a <var title="">port</var>, a
<var title="">resource name</var>, and a <var title="">secure</var>
flag, or they fail.</p>
<ol>
<li><p>If the <var title="">url</var> string is not an
<span>absolute URL</span>, then fail this algorithm. <a
href="#refsWEBADDRESSES">[WEBADDRESSES]</a></p></li>
<li>
<p><span title="resolve a url">Resolve</span> the <var
title="">url</var> string using the <span>resolve a Web
address</span> algorithm defined by the Web addresses
specification, with the <span>URL character encoding</span> set to
UTF-8. <a href="#refsWEBADDRESSES">[WEBADDRESSES]</a> <a
href="#refsRFC3629">[RFC3629]</a></p> <!-- the URL character
encoding is used to escape the query component -->
<p class="note">It doesn't matter what it is resolved relative to,
since we already know it is an <span>absolute URL</span> at this
point.</p>
</li>
<li><p>If <var title="">url</var> does not have a <span
title="url-scheme"><scheme></span> component whose value,
when <span>converted to ASCII lowercase</span>, is either "<code
title="">ws</code>" or "<code title="">wss</code>", then fail this
algorithm.</p></li>
<li><p>If <var title="">url</var> has a <span
title="url-fragment"><fragment></span> component, then fail
this algorithm.</p></li>
<li><p>If the <span title="url-scheme"><scheme></span>
component of <var title="">url</var> is "<code title="">ws</code>",
set <var title="">secure</var> to false; otherwise, the <span
title="url-scheme"><scheme></span> component is "<code
title="">wss</code>", set <var title="">secure</var> to
true.</p></li>
<li><p>Let <var title="">host</var> be the value of the <span
title="url-host"><host></span> component of <var
title="">url</var>, <span>converted to ASCII
lowercase</span>.</p></li> <!-- at this point this is
Punycode-encoded already -->
<li><p>If <var title="">url</var> has a <span
title="url-port"><port></span> component, then let <var
title="">port</var> be that component's value; otherwise, there is
no explicit <var title="">port</var>.</p></li>
<li><p>If there is no explicit <var title="">port</var>, then: if
<var title="">secure</var> is false, let <var title="">port</var>
be 80, otherwise let <var title="">port</var> be 443.</p></li>
<li><p>Let <var title="">resource name</var> be the value of the
<span title="url-path"><path></span> component (which might
be empty) of <var title="">url</var>.</p></li> <!-- at this point
this is UTF-8 encoded and %-escaped -->
<li><p>If <var title="">resource name</var> is the empty string,
set it to a single character U+002F SOLIDUS (/).</p></li>
<li><p>If <var title="">url</var> has a <span
title="url-query"><query></span> component, then append a
single U+003F QUESTION MARK character (?) to <var title="">resource
name</var>, followed by the value of the <span
title="url-query"><query></span> component.</p></li> <!-- at
this point this is UTF-8 encoded and %-escaped -->
<li><p>Return <var title="">host</var>, <var title="">port</var>,
<var title="">resource name</var>, and <var
title="">secure</var>.</p></li>
</ol>
<h6>Constructing Web Socket URLs</h6>
<p>The steps to <dfn>construct a Web Socket URL</dfn> from a <var
title="">host</var>, a <var title="">port</var>, a <var
title="">resource name</var>, and a <var title="">secure</var> flag,
are as follows:</p>
<ol>
<li>Let <var title="">url</var> be the empty string.</li>
<li>If the <var title="">secure</var> flag is false, then append
the string "<code title="">ws://</code>" to <var
title="">url</var>. Otherwise, append the string "<code
title="">wss://</code>" to <var title="">url</var>.</li>
<li>Append <var title="">host</var> to <var
title="">url</var>.</li>
<li>If the <var title="">secure</var> flag is false and port is
not 80, or if the <var title="">secure</var> flag is true and
port is not 443, then append the string "<code title="">:</code>"
followed by <var title="">port</var> to <var
title="">url</var>.</li>
<li>Append <var title="">resource name</var> to <var
title="">url</var>.</li>
<li>Return <var title="">url</var>.</li>
</ol>
<h5>Client-side requirements</h5>
<p><i>This section only applies to user agents, not to
servers.</i></p>
<p class="note">This specification doesn't currently define a limit
to the number of simultaneous connections that a client can
establish to a server.</p>
<h6>Handshake</h6>
<p>When the user agent is to <dfn>establish a Web Socket
connection</dfn> to a host <var title="">host</var>, on a port <var
title="">port</var>, from an origin whose <span title="ASCII
serialization of an origin">ASCII serialization</span> is <var
title="">origin</var>, with a flag <var title="">secure</var>, with
a string giving a <var title="">resource name</var>, and optionally
with a string giving a <var title="">protocol</var>, it must run the
following steps. The <var title="">host</var> must be ASCII-only
(i.e. it must have been punycode-encoded already if necessary). The
<var title="">resource name</var> and <var title="">protocol</var>
strings must be non-empty strings of ASCII characters in the range
U+0020 to U+007E. The <var title="">resource name</var> string must
start with a U+002F SOLIDUS character (/) and must not contain a
U+0020 SPACE character. <a href="#refsORIGIN">[ORIGIN]</a></p>
<ol>
<li>
<p>If the user agent already has a Web Socket connection to the
remote host (IP address) identified by <var title="">host</var>,
even if known by another name, wait until that connection has been
<span title="Web Socket connection is
established">established</span> or for that connection to have
<span title="fail the Web Socket connection">failed</span>.</p>
<p class="note">This makes it harder for a script to perform a
denial of service attack by just opening a large number of Web
Socket connections to a remote host.</p>
<p class="note">There is no limit to the number of <span
title="Web Socket connection is established">established</span>
Web Socket connections a user agent can have with a single remote
host. Servers can refuse to connect users with an excessive number
of connections, or disconnect resource-hogging users when
suffering high load.</p>
</li>
<li>
<p><i>Connect</i>: If the user agent is configured to use a proxy
when using the Web Socket protocol to connect to host <var
title="">host</var> and/or port <var title="">port</var>, then
connect to that proxy and ask it to open a TCP/IP connection to
the host given by <var title="">host</var> and the port given by
<var title="">port</var>.</p>
<div class="example">
<p>For example, if the user agent uses an HTTP proxy for all
traffic, then if it was to try to connect to port 80 on server
example.com, it might send the following lines to the proxy
server:</p>
<pre>CONNECT example.com:80 HTTP/1.1
Host: example.com</pre>
<p>If there was a password, the connection might look like:</p>
<pre>CONNECT example.com:80 HTTP/1.1
Host: example.com
Proxy-authorization: Basic ZWRuYW1vZGU6bm9jYXBlcyE=</pre>
</div>
<p>Otherwise, if the user agent is not configured to use a proxy,
then open a TCP/IP connection to the host given by <var
title="">host</var> and the port given by <var
title="">port</var>.</p>
<p class="note">Implementations that do not expose explicit UI for
selecting a proxy for Web Socket connections separate from other
proxies are encouraged to use a SOCKS proxy for Web Socket
connections, if available, or failing that, to prefer the proxy
configured for HTTPS connections over the proxy configured for
HTTP connections.</p>
<p>For the purpose of proxy autoconfiguration scripts, the
<span>URL</span> to pass the function must be constructed from
<var title="">host</var>, <var title="">port</var>, <var
title="">resource name</var>, and the <var title="">secure</var>
flag using the steps to <span>construct a Web Socket
URL</span>.</p>
<p class="note">The Web Socket protocol can be identified in proxy
autoconfiguration scripts from the scheme ("<code
title="">ws:</code>" for unencrypted connections and "<code
title="">wss:</code>" for encrypted connections).</p>
</li>
<li><p>If the connection could not be opened, then <span>fail the
Web Socket connection</span> and abort these steps.</p></li>
<li>
<p>If <var title="">secure</var> is true, perform a TLS handshake
over the connection. If this fails (e.g. the server's certificate
could not be verified), then <span>fail the Web Socket
connection</span> and abort these steps. Otherwise, all further
communication on this channel must run through the encrypted
tunnel. <a href="#refsRFC2246">[RFC2246]</a></p>
<p>User agents must use the Server Name Indication extension in
the TLS handshake. <a href="#refsRFC4366">[RFC4366]</a></p>
</li>
<li>
<p>Send the following bytes to the remote side (the server):</p>
<pre>47 45 54 20</pre>
<p>Send the <var title="">resource name</var> value, encoded as
ASCII.</p>
<p>Send the following bytes:</p>
<pre>20 48 54 54 50 2F 31 2E 31 0D 0A 55 70 67 72 61
64 65 3A 20 57 65 62 53 6F 63 6B 65 74 0D 0A 43
6F 6E 6E 65 63 74 69 6F 6E 3A 20 55 70 67 72 61
64 65 0D 0A</pre>
<p class="note">The string "GET ", the path,
" HTTP/1.1", CRLF, the string "Upgrade: WebSocket",
CRLF, and the string "Connection: Upgrade", CRLF.</p>
</li>
<li>
<p>Send the following bytes:</p>
<pre>48 6F 73 74 3A 20</pre>
<p>Send the <var title="">host</var> value, <span>converted to
ASCII lowercase</span>, and encoded as ASCII.</p>
<p>If <var title="">secure</var> is false, and <var
title="">port</var> is not 80, or if <var title="">secure</var> is
true, and <var title="">port</var> is not 443, then send an 0x3A
byte (ASCII :) followed by the value of <var title="">port</var>,
expressed as a base-ten integer, encoded as ASCII.</p>
<p>Send the following bytes:</p>
<pre>0D 0A</pre>
<p class="note">The string "Host: ", the host, and CRLF.</p>
</li>
<li>
<p>Send the following bytes:</p>
<pre>4F 72 69 67 69 6E 3A 20</pre>
<p>Send the <var title="">origin</var> value, <span>converted to
ASCII lowercase</span>, encoded as ASCII. <a
href="#refsORIGIN">[ORIGIN]</a></p>
<p class="note">The <var title="">origin</var> value is a string
that was passed to this algorithm.</p>
<p>Send the following bytes:</p>
<pre>0D 0A</pre>
<p class="note">The string "Origin: ", the origin, and CRLF.</p> <!-- http-origin -->
</li>
<li>
<p>If there is no <var title="">protocol</var>, then skip this step.</p>
<p>Otherwise, send the following bytes:</p>
<pre>57 65 62 53 6F 63 6B 65 74 2D 50 72 6F 74 6F 63
6F 6C 3A 20</pre>
<p>Send the <var title="">protocol</var> value, encoded as
ASCII.</p>
<p>Send the following bytes:</p>
<pre>0d 0a</pre>
<p class="note">The string "WebSocket-Protocol: ", the
protocol, and CRLF.</p>
</li>
<li>
<p>If the client has any <!--(v2-ws-auth) authentication
information or--> cookies that would be relevant to a resource
accessed over HTTP, if <var title="">secure</var> is false, or
HTTPS, if it is true, on host <var title="">host</var>, port <var
title="">port</var>, with <var title="">resource name</var> as the
path (and possibly query parameters), then HTTP headers that would
be appropriate for that information should be sent at this point.
<!--END complete-->
<a href="#refsRFC2616">[RFC2616]</a>
<a href="#refsRFC2109">[RFC2109]</a>
<a href="#refsRFC2965">[RFC2965]</a>
<!--START complete--><!--END websocket-protocol-->
<a href="#refsHTTP">[HTTP]</a>
<a href="#refsCOOKIES">[COOKIES]</a>
<!--START websocket-protocol-->
</p>
<p>Each header must be on a line of its own (each ending with a
CRLF sequence). For the purposes of this step, each header must
not be split into multiple lines (despite HTTP otherwise allowing
this with continuation lines).</p>
<!--(v2-ws-auth)
<div class="example">
<p>For example, if the server had a username and password that
applied to <code title="">http://example.com/socket</code>, and
the Web Socket was being opened to <code
title="">ws://example.com/socket</code>, it could send
them:</p>
<pre>Authorization: Basic d2FsbGU6ZXZl</pre>
</div>
-->
</li>
<li>
<p>Send the following bytes:</p>
<pre>0d 0a</pre>
<p class="note">Just a CRLF (a blank line).</p>
</li>
<li>
<p>Read bytes from the server until either the connection closes,
or a 0x0A byte is read. Let <var title="">header</var> be these
bytes, including the 0x0A byte.</p>
<p>If <var title="">header</var> is not at least two bytes long,
or if the last two bytes aren't 0x0D and 0x0A respectively, then
<span>fail the Web Socket connection</span> and abort these
steps.</p>
<p>User agents may apply a timeout to this step, <span title="fail
the Web Socket connection">failing the Web Socket
connection</span> if the server does not send back data in a
suitable time period.</p>
</li>
<li>
<p>If <var title="">header</var> consists of 44 bytes that exactly
match the following, then let <var title="">mode</var> be <i
title="">normal</i>.</p>
<pre>48 54 54 50 2F 31 2E 31 20 31 30 31 20 57 65 62
20 53 6F 63 6B 65 74 20 50 72 6F 74 6F 63 6F 6C
20 48 61 6E 64 73 68 61 6B 65 0D 0A</pre>
<p class="note">The string
"HTTP/1.1 101 Web Socket Protocol Handshake"
followed by a CRLF pair.</p>
<p class="note">Note that this means that if a server responds
with a Web Socket handshake but with the string "HTTP/1.0" or
"HTTP/1.2" at the front, a normal Web Socket connection will not
be established.</p> <!-- we might update this as HTTP is updated,
depending on whether it remains compatible or whatnot -->
<p>Otherwise, let <var title="">code</var> be the substring of
<var title="">header</var> that starts from the byte after the
first 0x20 byte, and ends with the byte before the second 0x20
byte. If there are not at least two 0x20 bytes in <var
title="">header</var>, then <span>fail the Web Socket
connection</span> and abort these steps.</p>
<!--(v2-redirect)
<p>If <var title="">code</var>, interpreted as ASCII, is either
"<code title="">301</code>", "<code title="">302</code>", "<code
title="">303</code>", "<code title="">307</code>", then let <var
title="">mode</var> be <i title="">redirect</i>.</p>
-->
<!--(v2-ws-auth)
<p>If <var title="">code</var>, interpreted as ASCII, is "<code
title="">401</code>", then let <var title="">mode</var> be <i
title="">authenticate</i>.</p>
-->
<p>If <var title="">code</var>, interpreted as ASCII, is "<code
title="">407</code>", then either close the connection and jump
back to step 2, providing appropriate authentication information,
or <span>fail the Web Socket connection</span>. 407 is the code
used by HTTP meaning "Proxy Authentication Required". User agents
that support proxy authentication must interpret the response as
defined by HTTP (e.g. to find and interpret the <code
title="http-Proxy-Authenticate">Proxy-Authenticate</code>
header).</p>
<p>Otherwise, <span>fail the Web Socket connection</span> and
abort these steps.</p>
</li>
<li>
<p>If <var title="">mode</var> is <i title="">normal</i>, then
read 41 bytes from the server.</p>
<p>If the connection closes before 41 bytes are received, or if
the 41 bytes aren't exactly equal to the following bytes, then
<span>fail the Web Socket connection</span> and abort these
steps.</p>
<pre>55 70 67 72 61 64 65 3A 20 57 65 62 53 6F 63 6B
65 74 0D 0A 43 6F 6E 6E 65 63 74 69 6F 6E 3A 20
55 70 67 72 61 64 65 0D 0A</pre>
<p class="note">The string "Upgrade: WebSocket", CRLF, the
string "Connection: Upgrade", CRLF.</p>
<p>User agents may apply a timeout to this step, <span title="fail
the Web Socket connection">failing the Web Socket
connection</span> if the server does not respond with the above
bytes within a suitable time period.</p>
<!--(v2-ws-auth) (v2-redirect)
<p class="note">This step is skipped if <var title="">mode</var>
is <i title="">redirect</i> or <i title="">authenticate</i>.</p>
-->
</li>
<li><p>Let <var title="">headers</var> be a list of name-value
pairs, initially empty.</p></li>
<li id="ws-ua-header-loop"><p><i title="">Header</i>: Let <var
title="">name</var> and <var title="">value</var> be empty byte
arrays.</p></li>
<li>
<p>Read a byte from the server.</p>
<p>If the connection closes before this byte is received, then
<span>fail the Web Socket connection</span> and abort these
steps.</p>
<p>Otherwise, handle the byte as described in the appropriate
entry below:</p>
<dl class="switch">
<dt>If the byte is 0x0D (ASCII CR)</dt>
<dd>If the <var title="">name</var> byte array is empty, then
jump to the <a href="#ws-ua-headers-processing">headers
processing</a> step. Otherwise, <span>fail the Web Socket
connection</span> and abort these steps.</dd>
<dt>If the byte is 0x0A (ASCII LF)</dt>
<dd><span>Fail the Web Socket connection</span> and abort these
steps.</dd>
<dt>If the byte is 0x3A (ASCII :)</dt>
<dd>Move on to the next step.</dd>
<dt>If the byte is in the range 0x41 to 0x5A (ASCII A-Z)</dt>
<dd>Append a byte whose value is the byte's value plus 0x20 to
the <var title="">name</var> byte array and redo this step for
the next byte.</dd>
<dt>Otherwise</dt>
<dd>Append the byte to the <var title="">name</var> byte
array and redo this step for the next byte.</dd>
</dl>
<p class="note">This reads a header name, terminated by a colon,
converting upper-case ASCII letters to lowercase, and aborting if
a stray CR or LF is found.</p>
</li>
<li>
<p>Read a byte from the server.</p>
<p>If the connection closes before this byte is received, then
<span>fail the Web Socket connection</span> and abort these
steps.</p>
<p>Otherwise, handle the byte as described in the appropriate
entry below:</p>
<dl class="switch">
<dt>If the byte is 0x20 (ASCII space)</dt>
<dd>Ignore the byte and move on to the next step.</dd>
<dt>Otherwise</dt>
<dd>Treat the byte as described by the list in the next step,
then move on to that next step for real.</dd>
</dl>
<p class="note">This skips past a space character after the colon,
if necessary.</p>
</li>
<li>
<p>Read a byte from the server.</p>
<p>If the connection closes before this byte is received, then
<span>fail the Web Socket connection</span> and abort these
steps.</p>
<p>Otherwise, handle the byte as described in the appropriate
entry below:</p>
<dl class="switch">
<dt>If the byte is 0x0D (ASCII CR)</dt>
<dd>Move on to the next step.</dd>
<dt>If the byte is 0x0A (ASCII LF)</dt>
<dd><span>Fail the Web Socket connection</span> and abort these
steps.</dd>
<dt>Otherwise</dt>
<dd>Append the byte to the <var title="">value</var> byte array
and redo this step for the next byte.</dd>
</dl>
<p class="note">This reads a header value, terminated by a
CRLF.</p>
</li>
<li>
<p>Read a byte from the server.</p>
<p>If the connection closes before this byte is received, or if
the byte is not a 0x0A byte (ASCII LF), then <span>fail the Web
Socket connection</span> and abort these steps.</p>
<p class="note">This skips past the LF byte of the CRLF after the
header.</p>
</li>
<li>
<p>Append an entry to the <var title="">headers</var> list that
has the name given by the string obtained by interpreting the <var
title="">name</var> byte array as a UTF-8 byte stream and the
value given by the string obtained by interpreting the <var
title="">value</var> byte array as a UTF-8 byte stream.</p>
</li>
<li>
<p>Return to the "<a href="#ws-ua-header-loop">Header</a>" step
above.</p>
</li>
<li id="ws-ua-headers-processing">
<p><i>Headers processing</i>: Read a byte from the server.</p>
<p>If the connection closes before this byte is received, or if
the byte is not a 0x0A byte (ASCII LF), then <span>fail the Web
Socket connection</span> and abort these steps.</p>
<p class="note">This skips past the LF byte of the CRLF after the
blank line after the headers.</p>
</li>
<li>
<p>If <var title="">mode</var> is <i title="">normal</i>, then: If
there is not exactly one entry in the <var title="">headers</var>
list whose name is "<code
title="http-websocket-origin">websocket-origin</code>", or if
there is not exactly one entry in the <var title="">headers</var>
list whose name is "<code
title="http-websocket-location">websocket-location</code>", or if
the <var title="">protocol</var> was specified but there is not
exactly one entry in the <var title="">headers</var> list whose
name is "<code
title="http-websocket-protocol">websocket-protocol</code>", or if
there are any entries in the <var title="">headers</var> list
whose names are the empty string, then <span>fail the Web Socket
connection</span> and abort these steps. Otherwise, handle each
entry in the <var title="">headers</var> list as follows:</p>
<dl class="switch">
<dt>If the entry's name is "<code
title="http-websocket-origin">websocket-origin</code>"</dt>
<dd><p>If the value is not exactly equal to <var
title="">origin</var>, <span>converted to ASCII lowercase</span>,
then <span>fail the Web Socket connection</span> and abort these
steps. <a href="#refsORIGIN">[ORIGIN]</a></p></dd>
<dt>If the entry's name is "<code
title="http-websocket-location">websocket-location</code>"</dt>
<dd>
<p>If the value is not exactly equal to a string obtained from
the steps to <span>construct a Web Socket URL</span> from <var
title="">host</var>, <var title="">port</var>, <var
title="">resource name</var>, and the <var title="">secure</var>
flag, then <span>fail the Web Socket connection</span> and abort
these steps.</p>
</dd>
<dt>If the entry's name is "<code
title="http-websocket-protocol">websocket-protocol</code>"</dt>
<dd><p>If there was a <var title="">protocol</var> specified, and
the value is not exactly equal to <var title="">protocol</var>,
then <span>fail the Web Socket connection</span> and abort these
steps. (If no <var title="">protocol</var> was specified, the
header is ignored.)</p></dd>
<dt>If the entry's name is "<code
title="http-setcookie">set-cookie</code>" or "<code
title="http-setcookie2">set-cookie2</code>" or another
cookie-related header name</dt>
<dd><p>Handle the cookie as defined by the appropriate
specification, with the resource being the one with the host <var
title="">host</var>, the port <var title="">port</var>, the path
(and possibly query parameters) <var title="">resource
name</var>, and the scheme <code title="">http</code> if <var
title="">secure</var> is false and <code title="">https</code> if
<var title="">secure</var> is true.
<!--END complete-->
<a href="#refsRFC2109">[RFC2109]</a>
<a href="#refsRFC2965">[RFC2965]</a>
<!--START complete--><!--END websocket-protocol-->
<a href="#refsCOOKIES">[COOKIES]</a>
<!--START websocket-protocol-->
</p></dd>
<dt>Any other name</dt>
<dd>Ignore it.</dd>
</dl>
<hr>
<!--(v2-redirect)
redirect support
we should probably reintroduce this at some point, with the
multi-origin semantics described in [ORIGIN] applying. (http-origin)
<p>If <var title="">mode</var> is <i title="">redirect</i>, then:
If there is not exactly one entry in the <var
title="">headers</var> list whose name is "<code
title="">location</code>", then <span>fail the Web Socket
connection</span> and abort these steps. Otherwise, handle each
entry in the <var title="">headers</var> list as follows:</p>
<dl class="switch">
<dt>If the entry's name is "<code
title="">location</code>"</dt>
<dd>
<ol>
<li><p>Let <var title="">was secure</var> have the value of
<var title="">secure</var>.</p></li>
<li><p><span>Parse a Web Socket URL's components</span> from
the <var title="">url</var> argument, to obtain new values for
<var title="">host</var>, <var title="">port</var>, <var
title="">resource name</var>, and <var
title="">secure</var>. If this fails, <span>fail the Web Socket
connection</span> and abort these steps.</p></li>
<li><p>If <var title="">was secure</var> is true but <var
title="">secure</var> is now false, <span>fail the Web Socket
connection</span> and abort these steps.</p></li>
<li><p>If <var title="">port</var> is a port to which the user
agent is configured to block access, then <span>fail the Web
Socket connection</span> and abort these steps. (User agents
typically block access to well-known ports like SMTP.)</p></li>
<li><p>Close the connection if the server has not already done
so.</p></li>
<li><p>Jump back to the first step of the overall algorithm
(the very top of the handshake).</p></li>
</ol>
</dd>
<dt>Any other name</dt>
<dd>Ignore it.</dd>
</dl>
-->
<!--(v2-ws-auth)
<hr>
<p>If <var title="">mode</var> is <i title="">authenticate</i>,
then: If there is not exactly one entry in the <var
title="">headers</var> list whose name is "<code
title="">www-authenticate</code>", then <span>fail the Web Socket
connection</span> and abort these steps. Otherwise, handle each
entry in the <var title="">headers</var> list as follows:</p>
<dl class="switch">
<dt>If the entry's name is "<code
title="">www-authenticate</code>"</dt>
<dd><p>Obtain credentials in a manner consistent with the
requirements for handling the <code>WWW-Authenticate</code>
header in HTTP, and then close the connection (if the server has
not already done so) and jump back to the step labeled
<i>connect</i>, including the relevant authentication headers in
the new request.
--><!--END complete--><!--
<a href="#refsRFC2616">[RFC2616]</a>
--><!--START complete--><!--END websocket-protocol--><!--
<a href="#refsHTTP">[HTTP]</a>
--><!--START websocket-protocol--><!--
</p></dd>
<dt>Any other name</dt>
<dd>Ignore it.</dd>
</dl>
-->
</li>
<li>
<p>The <dfn>Web Socket connection is established</dfn>. Now the
user agent must send and receive to and from the connection as
described in the next section.</p>
</li>
</ol>
<h6>Data framing</h6>
<p>Once a <span>Web Socket connection is established</span>, the
user agent must run through the following state machine for the
bytes sent by the server.</p>
<ol>
<li>
<p>Try to read a byte from the server. Let <var title="">frame
type</var> be that byte.</p>
<p>If no byte could be read because the <span>Web Socket
connection is closed</span>, then abort.</p>
</li>
<li>
<p>Handle the <var title="">frame type</var> byte as follows:</p>
<dl>
<dt>If the high-order bit of the <var title="">frame type</var>
byte is set (i.e. if <var title="">frame type</var> <i
title="">and</i>ed with 0x80 returns 0x80)</dt>
<dd>
<p>Run these steps. If at any point during these steps a read is
attempted but fails because the <span>Web Socket connection is
closed</span>, then abort.</p>
<ol>
<li><p>Let <var title="">length</var> be zero.</p></li>
<li id="ws-cd-length"><p><i>Length</i>: Read a byte, let <var
title="">b</var> be that byte.</p></li>
<li><p>Let <var title="">b<sub title="">v</sub></var> be
integer corresponding to the low 7 bits of <var title="">b</var>
(the value you would get by <i>and</i>ing <var title="">b</var>
with 0x7F).</p></li>
<li><p>Multiply <var title="">length</var> by 128, add <var
title="">b<sub title="">v</sub></var> to that result, and store
the final result in <var title="">length</var>.</p></li>
<li><p>If the high-order bit of <var title="">b</var> is set
(i.e. if <var title="">b</var> <i title="">and</i>ed with 0x80
returns 0x80), then return to the step above labeled <a
href="#ws-cd-length"><i>length</i></a>.</p></li>
<li><p>Read <var title="">length</var> bytes.</p></li>
<li><p>Discard the read bytes.</p></li>
</ol>
</dd>
<dt>If the high-order bit of the <var title="">frame type</var>
byte is <em>not</em> set (i.e. if <var title="">frame type</var>
<i title="">and</i>ed with 0x80 returns 0x00)</dt>
<dd>
<p>Run these steps. If at any point during these steps a read is
attempted but fails because the <span>Web Socket connection is
closed</span>, then abort.</p>
<ol>
<li><p>Let <var title="">raw data</var> be an empty byte array.</p></li>
<li id="ws-cd-data"><p><i>Data</i>: Read a byte, let <var
title="">b</var> be that byte. If the client runs out of
resources for buffering the incoming data, or hits an
artificial resource limit intended to avoid resource
starvation, then it must <span>fail the Web Socket
connection</span> and abort these steps.</p>
<li><p>If <var title="">b</var> is not 0xFF, then append <var
title="">b</var> to <var title="">raw data</var> and return to
the previous step (labeled <a
href="#ws-cd-data"><i>data</i></a>).</p></li>
<li><p>Interpret <var title="">raw data</var> as a UTF-8
string, and store that string in <var title="">data</var>.</p>
<li><p>If <var title="">frame type</var> is 0x00, then <dfn>a
message has been received</dfn> with text <var
title="">data</var>. Otherwise, discard the data.</p></li>
</ol>
</dd>
</dl>
</li>
<li><p>Return to the first step to read the next byte.</p></li>
</ol>
<p>If the user agent is faced with content that is too large to be
handled appropriately, then it must <span>fail the Web Socket
connection</span>.</p>
<hr>
<p>Once a <span>Web Socket connection is established</span>, the
user agent must use the following steps to <dfn>send <var
title="">data</var> using the Web Socket</dfn>:</p>
<ol>
<li><p>Send a 0x00 byte to the server.</p></li>
<li><p>Encode <var title="">data</var> using UTF-8 and send the
resulting byte stream to the server.</p></li>
<li><p>Send a 0xFF byte to the server.</p></li>
</ol>
<p>If at any point there is a fatal problem with sending data to the
server, the user agent must <span>fail the Web Socket
connection</span>.</p>
<!-- v2: People often request the ability to send binary blobs over
this API; we should also look into allowing name/value pairs,
arrays, and numbers using send() instead of just strings and binary
data. -->
<h6>Closing the connection</h6>
<p>To <dfn>fail the Web Socket connection</dfn>, the user agent must
<span>close the Web Socket connection</span>, and may report the
problem to the user (which would be especially useful for
developers). However, user agents must not convey the failure
information to the script that attempted the connection in a way
distinguishable from the Web Socket being closed normally.</p>
<p>Except as indicated above or as specified by the application
layer (e.g. a script using the Web Socket API), user agents should
not close the connection.</p>
<h6>Handling errors in UTF-8</h6>
<p>When a client is to interpret a byte stream as UTF-8 but finds
that the byte stream is not in fact a valid UTF-8 stream, then any
bytes or sequences of bytes that are not valid UTF-8 sequences must
be interpreted as a U+FFFD REPLACEMENT CHARACTER.</p>
<h5>Server-side requirements</h5>
<p><i>This section only applies to servers.</i></p>
<h6>Reading the client's handshake</h6>
<p>When a client starts a Web Socket connection, it sends its part
of the handshake. This consists of a number of fields separated by
CRLF pairs (bytes 0x0D 0x0A).</p>
<p>The first field consists of three tokens separated by space
characters (byte 0x20). The first token is the string "GET", the
middle token is the resource name, and the third is the string
"HTTP/1.1".</p>
<p>If the first field does not have three tokens, or if the first
and third tokens aren't the strings given in the previous paragraph,
or if the second token doesn't begin with U+002F SOLIDUS character
(/), the server should abort the connection: it either represents an
errorneous Web Socket client or a connection from a client expecting
another protocol altogether.</p>
<p>The subsequent fields consist of a string representing a name, a
colon and a space (bytes 0x3A 0x20), and a string representing a
value. The possible names, and the meaning of their corresponding
values, are as follows:</p>
<dl>
<dt>Upgrade (bytes 55 70 67 72 61 64 65; always the first name-value pair)</dt>
<dd>
<p>Invariant part of the handshake. Will always have a value
consisting of bytes 57 65 62 53 6F 63 6B 65 74.</p>
</dd>
<dt>Connection (bytes 43 6F 6E 6E 65 63 74 69 6F 6E; always the second name-value pair)</dt>
<dd>
<p>Invariant part of the handshake. Will always have a value
consisting of bytes 55 70 67 72 61 64 65.</p>
</dd>
<dt>Host (bytes 48 6F 73 74; always the third name-value pair)</dt>
<dd>
<p>The value gives the hostname that the client intended to use
when opening the Web Socket. It would be of interest in particular
to virtual hosting environments, where one server might serve
multiple hosts, and might therefore want to return different
data. The value must be interpreted as UTF-8.</p>
</dd>
<dt>Origin (bytes 4F 72 69 67 69 6E; always the fourth name-value pair)</dt> <!-- http-origin -->
<dd>
<p>The value gives the scheme, hostname, and port (if it's not the
default port for the given scheme) of the page that asked the
client to open the Web Socket. It would be interesting if the
server's operator had deals with operators of other sites, since
the server could then decide how to respond (or indeed,
<em>whether</em> to respond) based on which site was requesting a
connection. The value must be interpreted as UTF-8.</p>
</dd>
<dt>WebSocket-Protocol (bytes 57 65 62 53 6F 63 6B 65 74 2D 50 72 6F 74 6F 63 6F 6C; optional, if present, will be the fifth name-value pair)</dt> <!-- http-websocket-protocol -->
<dd>
<p>The value gives the name of a subprotocol that the client is
intending to select. It would be interesting if the server
supports multiple protocols or protocol versions. The value must
be interpreted as UTF-8.</p>
</dd>
<dt>Other fields</dt>
<dd>
<p>Other fields can be used, such as "<code
title="">Cookie</code>"<!--(v2-ws-auth) or
"<code>Authorization</code>"-->, for authentication
purposes. Their semantics are equivalent to the semantics of the
HTTP headers with the same names.</p>
</dd>
</dl>
<p>A final field consisting of the empty string (two consecutive
CRLF pairs) indicates the end of the client's handshake.</p>
<p>Any fields that lack the colon-space separator must at a minimum
be discarded and may cause the server to disconnect.</p>
<h6>Sending the server's handshake</h6>
<p>When a client establishes a Web Socket connection to a server,
the server must either close the connection or send the server
handshake. Servers may read part or all of the client's handshake
before closing the connection or sending all of their side of the
handshake; indeed, in some cases this is necessary as the server
might need to use some of the information in the client's handshake
to construct it's own handshake.</p>
<p>If the server supports encryption, then the server must perform a
TLS handshake over the connection before sending the server
handshake. If this fails (e.g. the client indicated a host name in
the extended client hello "server_name" extension that the server
does not host), then the server must close the connection;
otherwise, all further communication for the connection (including
the server handshake) must run through the encrypted tunnel. <a
href="#refsRFC2246">[RFC2246]</a></p>
<p>To send the server handshake, the server must first establish the
following information:</p>
<dl>
<dt><var title="">origin</var></dt>
<dd>The <span title="ASCII serialization of an origin">ASCII
serialization</span> of the origin that the server is willing to
communicate with. If the server can respond to requests from
multiple origins (or indeed, all origins), then the value should be
derived from the client's handshake, specifically from the "Origin"
field. <a href="#refsORIGIN">[ORIGIN]</a></dd>
<dt><var title="">host</var></dt>
<dd>The host name or IP address of the Web Socket server, as it is
to be addressed by clients. The host name must be punycode-encoded
if necessary. If the server can respond to requests to multiple
hosts (e.g. in a virtual hosting environment), then the value
should be derived from the client's handshake, specifically from
the "Host" field.</dd>
<dt><var title="">port</var></dt>
<dd>The port number on which the server expected and/or received
the connection.</dd>
<dt><var title="">resource name</var></dt>
<dd>An identifier for the service provided by the server. If the
server provides multiple services, then the value should be derived
from the client's handshake, specifically from the "Host"
field.</dd>
<dt><var title="">secure flag</var><dt>
<dd>True if the connection is encrypted or if the server expected
it to be encrypted; false otherwise.</dd>
<dt><var title="">subprotocol</var></dt>
<dd>Either null, or a string representing the subprotocol the
server is ready to use. If the server supports multiple
subprotocols, then the value should be derived from the client's
handshake, specifically from the "WebSocket-Protocol" field. The
absence of such a field is equivalent to the null value. The empty
string is not the same as the null value for these purposes.</dd>
</dl>
<p>Having established this information, the server must start the
handshake. The initial part of the server's handshake is invariant,
and must consist of the following bytes:</p>
<pre>48 54 54 50 2F 31 2E 31 20 31 30 31 20 57 65 62
20 53 6F 63 6B 65 74 20 50 72 6F 74 6F 63 6F 6C
20 48 61 6E 64 73 68 61 6B 65 0D 0A 55 70 67 72
61 64 65 3A 20 57 65 62 53 6F 63 6B 65 74 0D 0A
43 6F 6E 6E 65 63 74 69 6F 6E 3A 20 55 70 67 72
61 64 65 0D 0A 57 65 62 53 6F 63 6B 65 74 2D 4F
72 69 67 69 6E 3A 20</pre>
<p>These bytes must be the first bytes sent on the TCP connection by
the server. They must be followed by the <var title="">origin</var>
string, encoded as ASCII, followed by the following bytes:</p>
<pre>0D 0A 57 65 62 53 6F 63 6B 65 74 2D 4C 6F 63 61
74 69 6F 6E 3A 20</pre>
<p>The server must then send the string that results from <span
title="construct a Web Socket URL">constructing a Web Socket
URL</span> from <var title="">host</var>, <var title="">port</var>,
<var title="">resource name</var>, and <var title="">secure
flag</var>, encoded as ASCII.</p>
<p>If the <var title="">subprotocol</var> is not null, then the
server must then send the following bytes:</p>
<pre>0D 0A 57 65 62 53 6F 63 6B 65 74 2D 50 72 6F 74
6F 63 6F 6C 3A 20</pre>
<p>...followed by the <var title="">subprotocol</var> string,
encoded as ASCII.</p>
<p>Finally, the server must end its side of the handshake by sending
the four bytes 0x0D 0x0A 0x0D 0x0A to the client.</p>
<h6 id="ws-sd-framing">Data framing</h6>
<p>The server must run through the following steps to process the
bytes sent by the client:</p>
<ol>
<li id="wd-sd-frame"><p><i title="">Frame</i>: Read a byte from the
client. Let <var title="">type</var> be that byte.</p></li>
<li><p>If <var title="">type</var> is not a 0x00 byte, then the
server may disconnect from the client.</p>
<li>
<p>If the most significant bit of <var title="">type</var> is not
set, then run the following steps:</p>
<ol>
<li><p>Let <var title="">raw data</var> be an empty byte
array.</p></li>
<li id="ws-sd-data"><p><i>Data</i>: Read a byte, let <var
title="">b</var> be that byte.</p></li>
<li><p>If <var title="">b</var> is not 0xFF, then append <var
title="">b</var> to <var title="">raw data</var> and return to
the previous step (labeled <a
href="#ws-sd-data"><i>data</i></a>).</p></li>
<li><p>Interpret <var title="">raw data</var> as a UTF-8 string,
and apply whatever server-specific processing is to occur for the
resulting string (the message from the client).</p>
</ol>
<p>Otherwise, the most significant bit of <var title="">type</var>
is set. Run the following steps. This can never happen if <var
title="">type</var> is 0x00, and therefore these steps are not
necessary if the server aborts when <var title="">type</var> is
not 0x00, as allowed above.</p>
<ol>
<li><p>Let <var title="">length</var> be zero.</p></li>
<li id="ws-sd-length"><p><i>Length</i>: Read a byte, let <var
title="">b</var> be that byte.</p></li>
<li><p>Let <var title="">b<sub title="">v</sub></var> be
integer corresponding to the low 7 bits of <var title="">b</var>
(the value you would get by <i>and</i>ing <var title="">b</var>
with 0x7F).</p></li>
<li><p>Multiply <var title="">length</var> by 128, add <var
title="">b<sub title="">v</sub></var> to that result, and store
the final result in <var title="">length</var>.</p></li>
<li><p>If the high-order bit of <var title="">b</var> is set
(i.e. if <var title="">b</var> <i title="">and</i>ed with 0x80
returns 0x80), then return to the step above labeled <a
href="#ws-sd-length"><i>length</i></a>.</p></li>
<li><p>Read <var title="">length</var> bytes.</p></li>
<li><p>Discard the read bytes.</p></li>
</ol>
</li>
<li><p>Return to the step labeled <a
href="#ws-sd-frame"><i>frame</i></a>.</p></li>
</ol>
<hr>
<p>The server must run through the following steps to send strings
to the client:</p>
<ol>
<li><p>Send a 0x00 byte to the client to indicate the start of a
string.</p></li>
<li><p>Encode <var title="">data</var> using UTF-8 and send the
resulting byte stream to the client.</p></li>
<li><p>Send a 0xFF byte to the client to indicate the end of the
message.</p></li>
</ol>
<h6>Handling errors in UTF-8</h6>
<p>When a server is to interpret a byte stream as UTF-8 but finds
that the byte stream is not in fact a valid UTF-8 stream, behaviour
is undefined. A server could close the connection, convert invalid
byte sequences to U+FFFD REPLACEMENT CHARACTERs, store the data
verbatim, or perform application-specific processing. Subprotocols
layered on the Web Socket protocol might define specific behavior
for servers.</p>
<h5>Closing the connection</h5>
<p>To <dfn>close the Web Socket connection</dfn>, either the user
agent or the server closes the TCP/IP connection. There is no
closing handshake. When a user agent notices that the server has
closed its connection, it must immediately close its side of the
connection also. Whether the user agent or the server closes the
connection first, it is said that the <dfn>Web Socket connection is
closed</dfn>.</p>
<p>Servers may <span>close the Web Socket connection</span> whenever
desired. User agents should not <span>close the Web Socket
connection</span> arbitrarily.</p>
<h5>Security considerations</h5>
<p>While this protocol is intended to be used by scripts in Web
pages, it can also be used directly by hosts. Such hosts are acting
on their own behalf, and can therefore send fake "Origin" headers,
misleading the server. Servers should therefore be careful about
assuming that they are talking directly to scripts from known
origins, and must consider that they might be accessed in unexpected
ways. In particular, a server should not trust that any input is
valid.</p>
<p class="example">For example, if the server uses input as part of
SQL queries, all input text should be escaped before being passed to
the SQL server, lest the server be susceptible to SQL injection.</p>
<hr>
<p>Servers that are not intended to process input from any Web page
but only for certain sites should verify the "Origin" header is an
origin they expect, and should only respond with the corresponding
"WebSocket-Origin" if it is an accepted origin. Servers that only
accept input from one origin can just send back that value in the
"WebSocket-Origin" header, without bothering to check the client's
value.</p>
<hr>
<p>If at any time a server is faced with data that it does not
understand, or that violates some criteria by which the server
determines safety of input, or when the server sees a handshake that
does not correspond to the values the server is expecting
(e.g. incorrect path or origin), the server should just
disconnect. It is always safe to disconnect.</p>
<hr>
<p>The biggest security risk when sending text data using this
protocol is sending data using the wrong encoding. If an attacker
can trick the server into sending data encoded as ISO-8859-1
verbatim (for instance), rather than encoded as UTF-8, then the
attacker could inject arbitrary frames into the data stream.</p>
<h5>IANA considerations</h5>
<h6>Registration of <code title="">ws:</code> scheme</h6>
<p>A <code title="">ws:</code> URL identifies a Web Socket server
and resource name.</p>
<dl>
<dt>URI scheme name.</dt>
<dd>ws</dd>
<dt>Status.</dt>
<dd>Permanent.</dd>
<dt>URI scheme syntax.</dt>
<dd>
<p>In ABNF terms using the terminals from the URI specifications:
<!--END complete-->
<a href="#refsRFC5234">[RFC5234]</a>
<!--START complete--><!--END websocket-protocol-->
<a href="#refsABNF">[ABNF]</a>
<!--START websocket-protocol-->
<a href="#refsRFC3986">[RFC3986]</a>
</p>
<pre>"ws" ":" hier-part [ "?" query ]</pre>
<p>The path and query components form the resource name sent to
the server to identify the kind of service desired. Other
components have the meanings described in RFC3986.</p>
</dd>
<dt>URI scheme semantics.</dt>
<dd>The only operation for this scheme is to open a connection
using the Web Socket protocol.</dd>
<dt>Encoding considerations.</dt>
<dd>
<p>Characters in the host component that are excluded by the
syntax defined above must be converted from Unicode to ASCII by
applying the IDNA ToASCII algorithm to the Unicode host name, with
both the AllowUnassigned and UseSTD3ASCIIRules flags set, and
using the result of this algorithm as the host in the URI. <a
href="#refsRFC3490">[RFC3490]</a></p>
<p>Characters in other components that are excluded by the syntax
defined above must be converted from Unicode to ASCII by first
encoding the characters as UTF-8 and then replacing the
corresponding bytes using their percent-encoded form as defined in
the URI and IRI specification. <a
href="#refsRFC3986">[RFC3986]</a> <a
href="#refsRFC3987">[RFC3987]</a></p>
</dd>
<dt>Applications/protocols that use this URI scheme name.</dt>
<dd>Web Socket protocol.</dd>
<dt>Interoperability considerations.</dt>
<dd>None.</dd>
<dt>Security considerations.</dt>
<dd>See "Security considerations" section above.</dd>
<dt>Contact.</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Author/Change controller.</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>References.</dt>
<dd>This document.</dd>
</dl>
<h6>Registration of <code title="">wss:</code> scheme</h6>
<p>A <code title="">wss:</code> URL identifies a Web Socket server
and resource name, and indicates that traffic over that connection
is to be encrypted.</p>
<dl>
<dt>URI scheme name.</dt>
<dd>wss</dd>
<dt>Status.</dt>
<dd>Permanent.</dd>
<dt>URI scheme syntax.</dt>
<dd>
<p>In ABNF terms using the terminals from the URI specifications:
<!--END complete-->
<a href="#refsRFC5234">[RFC5234]</a>
<!--START complete--><!--END websocket-protocol-->
<a href="#refsABNF">[ABNF]</a>
<!--START websocket-protocol-->
<a href="#refsRFC3986">[RFC3986]</a></p>
<pre>"wss" ":" hier-part [ "?" query ]</pre>
<p>The path and query components form the resource name sent to
the server to identify the kind of service desired. Other
components have the meanings described in RFC3986.</p>
</dd>
<dt>URI scheme semantics.</dt>
<dd>The only operation for this scheme is to open a connection
using the Web Socket protocol, encrypted using TLS.</dd>
<dt>Encoding considerations.</dt>
<dd>
<p>Characters in the host component that are excluded by the
syntax defined above must be converted from Unicode to ASCII by
applying the IDNA ToASCII algorithm to the Unicode host name, with
both the AllowUnassigned and UseSTD3ASCIIRules flags set, and
using the result of this algorithm as the host in the URI. <a
href="#refsRFC3490">[RFC3490]</a></p>
<p>Characters in other components that are excluded by the syntax
defined above must be converted from Unicode to ASCII by first
encoding the characters as UTF-8 and then replacing the
corresponding bytes using their percent-encoded form as defined in
the URI and IRI specification. <a
href="#refsRFC3986">[RFC3986]</a> <a
href="#refsRFC3987">[RFC3987]</a></p>
</dd>
<dt>Applications/protocols that use this URI scheme name.</dt>
<dd>Web Socket protocol over TLS.</dd>
<dt>Interoperability considerations.</dt>
<dd>None.</dd>
<dt>Security considerations.</dt>
<dd>See "Security considerations" section above.</dd>
<dt>Contact.</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Author/Change controller.</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>References.</dt>
<dd>This document.</dd>
</dl>
<h6>Registration of the "<code title="">WebSocket</code>" HTTP Upgrade keyword</h6>
<dl>
<dt>Name of token.</dt>
<dd>WebSocket</dd>
<dt>Author/Change controller.</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Contact.</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>References.</dt>
<dd>This document.</dd>
</dl>
<h6><dfn title="http-websocket-origin"><code>WebSocket-Origin</code></dfn></h6>
<p>This section describes a header field for registration in the
Permanent Message Header Field Registry. <a
href="#refsRFC3864">[RFC3864]</a></p>
<dl>
<dt>Header field name</dt>
<dd>WebSocket-Origin</dd>
<dt>Applicable protocol</dt>
<dd>http</dd>
<dt>Status</dt>
<dd>reserved; do not use outside Web Socket handshake</dd>
<dt>Author/Change controller</dt>
<dd>IETF</dd>
<dt>Specification document(s)</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Related information</dt>
<dd>None.</dd>
</dl>
<p>The <code>WebSocket-Origin</code> header is used in the Web
Socket handshake. It is sent from the server to the client to
confirm the <span>origin</span> of the script that opened the
connection. This enables user agents to verify that the server is
willing to serve the script that opened the connection.</p>
<h6><dfn title="http-websocket-protocol"><code>WebSocket-Protocol</code></dfn></h6>
<p>This section describes a header field for registration in the
Permanent Message Header Field Registry. <a
href="#refsRFC3864">[RFC3864]</a></p>
<dl>
<dt>Header field name</dt>
<dd>WebSocket-Protocol</dd>
<dt>Applicable protocol</dt>
<dd>http</dd>
<dt>Status</dt>
<dd>reserved; do not use outside Web Socket handshake</dd>
<dt>Author/Change controller</dt>
<dd>IETF</dd>
<dt>Specification document(s)</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Related information</dt>
<dd>None.</dd>
</dl>
<p>The <code>WebSocket-Protocol</code> header is used in the Web
Socket handshake. It is sent from the client to the server and back
from the server to the client to confirm the subprotocol of the
connection. This enables scripts to both select a subprotocol and be
sure that the server agreed to serve that subprotocol.</p>
<h6><dfn title="http-websocket-location"><code>WebSocket-Location</code></dfn></h6>
<p>This section describes a header field for registration in the
Permanent Message Header Field Registry. <a
href="#refsRFC3864">[RFC3864]</a></p>
<dl>
<dt>Header field name</dt>
<dd>WebSocket-Location</dd>
<dt>Applicable protocol</dt>
<dd>http</dd>
<dt>Status</dt>
<dd>reserved; do not use outside Web Socket handshake</dd>
<dt>Author/Change controller</dt>
<dd>IETF</dd>
<dt>Specification document(s)</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Related information</dt>
<dd>None.</dd>
</dl>
<p>The <code>WebSocket-Location</code> header is used in the Web
Socket handshake. It is sent from the server to the client to
confirm the <span>URL</span> of the connection. This enables the
client to verify that the connection was established to the right
server, port, and path, instead of relying on the server to verify
that the requested host, port, and path are correct.</p>
<h5>Using the Web Socket protocol from other specifications</h5>
<p>The Web Socket protocol is intended to be used by another
specification to provide a generic mechanism for dynamic
author-defined content, e.g. in a specification defining a scripted
API.</p>
<p>Such a specification first needs to "<span>establish a Web Socket
connection</span>", providing that algorithm with:</p>
<ul>
<li>The destination, consisting of a <var title="">host</var> and a
<var title="">port</var>.</li>
<li>A <var title="">resource name</var>, which allows for multiple
services to be identified at one host and port.</li>
<li>A <var title="">secure</var> flag, which is true if the
connection is to be encrypted, and false otherwise.</li>
<li>An <span>ASCII serialization of an origin</span> that is being
made responsible for the connection. <a
href="#refsORIGIN">[ORIGIN]</a></li>
<li>Optionally a string identifying a <span>protocol</span> that is
to be layered over the Web Socket connection.</li>
</ul>
<p>The <var title="">host</var>, <var title="">port</var>, <var
title="">resource name</var>, and <var title="">secure</var> flag
are usually obtained from a <span>URL</span> using the steps to
<span>parse a Web Socket URL's components</span>. These steps fail
if the URL does not specify a Web Socket.</p>
<p>If a connection can be established, then it is said that the
"<span>Web Socket connection is established</span>".</p>
<p>If at any time the connection is to be closed, then the
specification needs to use the "<span>close the Web Socket
connection</span>" algorithm.</p>
<p>When the connection is closed, for any reason including failure
to establish the connection in the first place, it is said that the
"<span>Web Socket connection is closed</span>".</p>
<p>While a connection is open, the specification will need to handle
the cases when "<span>a Web Socket message has been received</span>"
with text <var title="">data</var>.</p>
<p>To send some text <var title="">data</var> to an open connection,
the specification needs to "<span>send <var title="">data</var>
using the Web Socket</span>".</p>
<!--END websocket-protocol-->
<!--END websocket-->
<!--START html--><!--START html5-->
<h3 id="crossDocumentMessages"><dfn>Cross-document messaging</dfn></h3>
<p>Web browsers, for security and privacy reasons, prevent documents
in different domains from affecting each other; that is, cross-site
scripting is disallowed.</p>
<p>While this is an important security feature, it prevents pages
from different domains from communicating even when those pages are
not hostile. This section introduces a messaging system that allows
documents to communicate with each other regardless of their source
domain, in a way designed to not enable cross-site scripting
attacks.</p>
<div class="impl">
<p>The <span>task source</span> for the <span
title="concept-task">tasks</span> in <span>cross-document
messaging</span> is the <dfn>posted message task source</dfn>.</p>
</div>
<h4>Introduction</h4>
<p><i>This section is non-normative.</i></p>
<div class="example">
<p>For example, if document A contains an <code>iframe</code>
element that contains document B, and script in document A calls
<code title="dom-window-postMessage-2">postMessage()</code> on the
<code>Window</code> object of document B, then a message event will
be fired on that object, marked as originating from the
<code>Window</code> of document A. The script in document A might
look like:</p>
<pre>var o = document.getElementsByTagName('iframe')[0];
o.contentWindow.postMessage('Hello world', 'http://b.example.org/');</pre>
<p>To register an event handler for incoming events, the script
would use <code title="">addEventListener()</code> (or similar
mechanisms). For example, the script in document B might look
like:</p>
<pre>window.addEventListener('message', receiver, false);
function receiver(e) {
if (e.origin == 'http://example.com') {
if (e.data == 'Hello world') {
e.source.postMessage('Hello', e.origin);
} else {
alert(e.data);
}
}
}</pre>
<p>This script first checks the domain is the expected domain, and
then looks at the message, which it either displays to the user, or
responds to by sending a message back to the document which sent
the message in the first place.</p>
</div>
<h4>Security</h4>
<div class="impl">
<h5>Authors</h5>
</div>
<p class="warning">Use of this API requires extra care to protect
users from hostile entities abusing a site for their own
purposes.</p>
<p>Authors should check the <code
title="dom-MessageEvent-origin">origin</code> attribute to ensure
that messages are only accepted from domains that they expect to
receive messages from. Otherwise, bugs in the author's message
handling code could be exploited by hostile sites.</p>
<p>Furthermore, even after checking the <code
title="dom-MessageEvent-origin">origin</code> attribute, authors
should also check that the data in question is of the expected
format. Otherwise, if the source of the event has been attacked
using a cross-site scripting flaw, further unchecked processing of
information sent using the <code
title="dom-window-postMessage-2">postMessage()</code> method could
result in the attack being propagated into the receiver.</p>
<p>Authors should not use the wildcard keyword (*) in the <var
title="">targetOrigin</var> argument in messages that contain any
confidential information, as otherwise there is no way to guarantee
that the message is only delivered to the recipient to which it was
intended.</p>
<div class="impl">
<h5>User agents</h5>
<p>The integrity of this API is based on the inability for scripts
of one <span>origin</span> to post arbitrary events (using <code
title="">dispatchEvent()</code> or otherwise) to objects in other
origins (those that are not the <span title="same
origin">same</span>).</p>
<p class="note">Implementors are urged to take extra care in the
implementation of this feature. It allows authors to transmit
information from one domain to another domain, which is normally
disallowed for security reasons. It also requires that UAs be
careful to allow access to certain properties but not others.</p>
</div>
<h4>Posting messages</h4>
<dl class="domintro">
<dt><var title="">window</var> . <code title="dom-window-postMessage-2">postMessage</code>(<var title="">message</var>, [ <var title="">ports</var>, ] <var title="">targetOrigin</var>)</dt>
<dd>
<p>Posts a message, optionally with an array of ports, to the
given window.</p>
<p>If the origin of the target window doesn't match the given
origin, the message is discarded, to avoid information leakage. To
send the message to the target regardless of origin, set the
target origin to "<code title="">*</code>".</p>
<p>Throws an <code>INVALID_STATE_ERR</code> if the <var
title="">ports</var> array is not null and it contains either null
entries or duplicate ports.</p>
</dd>
</dl>
<div class="impl">
<p>When a script invokes the <dfn
title="dom-window-postMessage-2"><code>postMessage(<var
title="">message</var>, <var
title="">targetOrigin</var>)</code></dfn> method (with only two
arguments) on a <code>Window</code> object, the user agent must
follow these steps:
<ol>
<li>
<p>If the value of the <var title="">targetOrigin</var> argument
is not a single U+002A ASTERISK character (*), and <span
title="resolve a url">resolving</span> it relative to the
<span>first script</span>'s <span title="script's base URL">base
URL</span> either fails or results in a <span>URL</span> with a
<code title="url-host-specific"><host-specific></code>
component that is neither empty nor a single U+002F SOLIDUS
character (/), then throw a <code>SYNTAX_ERR</code> exception and
abort the overall set of steps.</p>
</li>
<li>
<p>Let <var title="">message clone</var> be the result of
obtaining a <span>structured clone</span> of the <var
title="">message</var> argument. If this throws an exception, then
throw that exception and abort these steps.</p>
</li>
<li>
<p>Return from the <code
title="dom-window-postMessage-2">postMessage()</code> method, but
asynchronously continue running these steps.</p>
</li>
<li>
<p>If the <var title="">targetOrigin</var> argument has a value
other than a single literal U+002A ASTERISK character (*), and
the <code>Document</code> of the <code>Window</code> object on
which the method was invoked does not have the <span>same
origin</span> as <var title="">targetOrigin</var>, then abort
these steps silently.</p>
</li>
<li>
<p>Create an event that uses the <code>MessageEvent</code>
interface, with the event name <code
title="event-message">message</code>, which does not bubble, is
not cancelable, and has no default action. The <code
title="dom-MessageEvent-data">data</code> attribute must be set to
the value of <var title="">message clone</var>, the <code
title="dom-MessageEvent-origin">origin</code> attribute must be
set to the <span title="Unicode serialization of an
origin">Unicode serialization</span> of the <span>origin</span> of
the script that invoked the method, and the <code
title="dom-MessageEvent-source">source</code> attribute must be
set to the <span>script's global object</span>.</p> <!--
invariant: the global object is always a Window if the script can
see this method -->
</li>
<li>
<p><span>Queue a task</span> to dispatch the event created in the
previous step at the <code>Window</code> object on which the
method was invoked. The <span>task source</span> for this <span
title="concept-task">task</span> is the <span>posted message task
source</span>.</p>
</li>
</ol>
</div>
<div class="impl">
<h4>Posting messages with message ports</h4>
<p>When a script invokes the <dfn
title="dom-window-postMessage-3"><code>postMessage(<var
title="">message</var>, <var title="">ports</var>, <var
title="">targetOrigin</var>)</code></dfn> method (with three
arguments) on a <code>Window</code> object, the user agent must
follow these steps:
<ol>
<!-- EXCEPT WHERE NOTED, THESE STEPS ARE IDENTICAL TO THE PREVIOUS SECTION -->
<!-- one exception is the use of -3 instead of -2 in the xrefs -->
<li>
<p>If the value of the <var title="">targetOrigin</var> argument
is not a single U+002A ASTERISK character (*), and <span
title="resolve a url">resolving</span> it relative to the
<span>first script</span>'s <span title="script's base URL">base
URL</span> either fails or results in a <span>URL</span> with a
<code title="url-host-specific"><host-specific></code>
component that is neither empty nor a single U+002F SOLIDUS
character (/), then throw a <code>SYNTAX_ERR</code> exception and
abort the overall set of steps.</p>
</li>
<li>
<p>Let <var title="">message clone</var> be the result of
obtaining a <span>structured clone</span> of the <var
title="">message</var> argument. If this throws an exception, then
throw that exception and abort these steps.</p>
</li>
<li> <!-- NEW STEP -->
<p>If the <var title="">ports</var> argument is null, then
act as if the method had just been <span
title="dom-window-postMessage-2">called with two arguments</span>,
<var title="">message</var> and <var
title="">targetOrigin</var>.</p>
</li>
<li> <!-- NEW STEP -->
<p>If any of the entries in <var title="">ports</var> are null, if
any <code>MessagePort</code> object is listed in <var
title="">ports</var> more than once, or if any of the
<code>MessagePort</code> objects listed in <var
title="">ports</var> have already been cloned once before, then
throw an <code>INVALID_STATE_ERR</code> exception.</p>
</li>
<li> <!-- NEW STEP -->
<p>Let <var title="">new ports</var> be an empty array.</p>
<p>For each port in <var title="">ports</var> in turn,
obtain a new port by <span title="clone a port">cloning</span> the
port with the <code>Window</code> object on which the method was
invoked as the owner of the clone, and append the clone to the
<var title="">new ports</var> array.</p>
<p class="note">If the original <var title="">ports</var>
array was empty, then the <var title="">new ports</var> array will
also be empty.</p>
</li>
<li>
<p>Return from the <code
title="dom-window-postMessage-3">postMessage()</code> method, but
asynchronously continue running these steps.</p>
</li>
<li>
<p>If the <var title="">targetOrigin</var> argument has a value
other than a single literal U+002A ASTERISK character (*), and
the <code>Document</code> of the <code>Window</code> object on
which the method was invoked does not have the <span>same
origin</span> as <var title="">targetOrigin</var>, then abort
these steps silently.</p>
</li>
<li>
<p>Create an event that uses the <code>MessageEvent</code>
interface, with the event name <code
title="event-message">message</code>, which does not bubble, is
not cancelable, and has no default action. The <code
title="dom-MessageEvent-data">data</code> attribute must be set to
the value of <var title="">message clone</var>, the <code
title="dom-MessageEvent-origin">origin</code> attribute must be
set to the <span title="Unicode serialization of an
origin">Unicode serialization</span> of the <span>origin</span> of
the script that invoked the method, and the <code
title="dom-MessageEvent-source">source</code> attribute must be
set to the <span>script's global object</span>.</p> <!--
invariant: the global object is always a Window if the script can
see this method -->
</li>
<li> <!-- NEW STEP -->
<p>Let the <code
title="dom-MessageEvent-ports">ports</code> attribute
of the event be the <var title="">new ports</var> array.</p>
</li>
<li>
<p><span>Queue a task</span> to dispatch the event created in the
previous step at the <code>Window</code> object on which the
method was invoked. The <span>task source</span> for this <span
title="concept-task">task</span> is the <span>posted message task
source</span>.</p>
</li>
</ol>
<p class="note">These steps, with the exception of the second and
third steps and the penultimate step, are identical to those in the
previous section.</p>
<!-- v2: we can merge this section and the previous section when
implementations have shipped postMessage(). Anne asked that these
sections be kept separate so that implementors can avoid getting
confused with the 'port' step. -->
</div>
<h3><dfn>Channel messaging</dfn></h3>
<h4>Message channels</h4>
<pre class="idl">[<span title="dom-MessageChannel">Constructor</span>]
interface <dfn>MessageChannel</dfn> {
readonly attribute <span>MessagePort</span> <span title="dom-channel-port1">port1</span>;
readonly attribute <span>MessagePort</span> <span title="dom-channel-port2">port2</span>;
};</pre>
<dl class="domintro">
<dt><var title="">channel</var> = new <code title="dom-MessageChannel">MessageChannel</code>()</dt>
<dd>
<p>Returns a new <code>MessageChannel</code> object with two new <code>MessagePort</code> objects.</p>
</dd>
<dt><var title="">channel</var> . <code title="dom-MessageChannel-port1">port1</code></dt>
<dd>
<p>Returns the first <code>MessagePort</code> object.</p>
</dd>
<dt><var title="">channel</var> . <code title="dom-MessageChannel-port2">port2</code></dt>
<dd>
<p>Returns the second <code>MessagePort</code> object.</p>
</dd>
</dl>
<div class="impl">
<p>When the <dfn
title="dom-MessageChannel"><code>MessageChannel()</code></dfn>
constructor is called, it must run the following algorithm:</p>
<ol>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by the <span>script's global object</span>, and let <var
title="">port1</var> be that object.</p></li>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by the <span>script's global object</span>, and let <var
title="">port2</var> be that object.</p></li>
<li><p><span>Entangle</span> the <var title="">port1</var> and <var
title="">port2</var> objects.</p></li>
<li><p>Instantiate a new <code>MessageChannel</code> object, and
let <var title="">channel</var> be that object.</p></li>
<li><p>Let the <code title="dom-channel-port1">port1</code>
attribute of the <var title="">channel</var> object be <var
title="">port1</var>.</p>
<li><p>Let the <code title="dom-channel-port2">port2</code>
attribute of the <var title="">channel</var> object be <var
title="">port2</var>.</p>
<li><p>Return <var title="">channel</var>.</p></li>
</ol>
<p>This constructor must be visible when the <span>script's global
object</span> is either a <code>Window</code> object or an object
implementing the <code>WorkerUtils</code> interface.</p>
<p>The <dfn title="dom-channel-port1"><code>port1</code></dfn> and
<dfn title="dom-channel-port2"><code>port2</code></dfn> attributes
must return the values they were assigned when the
<code>MessageChannel</code> object was created.</p>
</div>
<h4>Message ports</h4>
<p>Each channel has two message ports. Data sent through one port is
received by the other port, and vice versa.</p>
<pre class="idl">typedef sequence<MessagePort> <dfn>MessagePortArray</dfn>;
interface <dfn>MessagePort</dfn> {
<!-- v2-onclose readonly attribute boolean <span title="dom-MessagePort-active">active</span>;
--> void <span title="dom-MessagePort-postMessage">postMessage</span>(in any message, in optional <span>MessagePortArray</span> ports);<!--
<span>MessagePort</span> <span title="dom-MessagePort-startConversation">startConversation</span>(in any message);-->
void <span title="dom-MessagePort-start">start</span>();
void <span title="dom-MessagePort-close">close</span>();
// event handlers
attribute <span>Function</span> <span title="handler-MessagePort-onmessage">onmessage</span>;
};
<span>MessagePort</span> implements <span>EventTarget</span>;</pre>
<dl class="domintro">
<!-- v2-onclose
<dt><var title="">port</var> . <code title="dom-MessagePort-active">active</code></dt>
<dd>
<p>Returns true if the port is still active; otherwise, returns false.</p>
</dd>
-->
<dt><var title="">port</var> . <code title="dom-MessagePort-poseMessage">postMessage</code>(<var title="">message</var> [, <var title="">ports</var>] )</dt>
<dd>
<p>Posts a message through the channel, optionally with the given
ports.</p>
<p>Throws an <code>INVALID_STATE_ERR</code> if the <var
title="">ports</var> array is not null and it contains either null
entries, duplicate ports, or the source or target port.</p>
</dd>
<dt><var title="">port</var> . <code title="dom-MessagePort-start">start</code>()</dt>
<dd>
<p>Begins dispatching messages received on the port.</p>
</dd>
<dt><var title="">port</var> . <code title="dom-MessagePort-close">close</code>()</dt>
<dd>
<p>Disconnects the port, so that it is no longer active.</p>
</dd>
</dl>
<div class="impl">
<p>Each <code>MessagePort</code> object can be entangled with
another (a symmetric relationship). Each <code>MessagePort</code>
object also has a <span>task source</span> called the <dfn>port
message queue</dfn>, initial empty. A <span>port message
queue</span> can be enabled or disabled, and is initially
disabled. Once enabled, a port can never be disabled again (though
messages in the queue can get moved to another queue or removed
altogether, which has much the same effect).</p>
<p>When the user agent is to <dfn>create a new
<code>MessagePort</code> object</dfn> owned by a <span>script's
global object</span> object <var title="">owner</var>, it must
instantiate a new <code>MessagePort</code> object, and let its owner
be <var title="">owner</var>.</p>
<hr>
<p>When the user agent is to <dfn>entangle</dfn> two
<code>MessagePort</code> objects, it must run the following
steps:</p>
<ol>
<li>
<p>If one of the ports is already entangled, then disentangle it
and the port that it was entangled with.</p>
<p class="note">If those two previously entangled ports were the
two ports of a <code>MessageChannel</code> object, then that
<code>MessageChannel</code> object no longer represents an actual
channel: the two ports in that object are no longer entangled.</p>
</li>
<li><p>Associate the two ports to be entangled, so that they form
the two parts of a new channel. (There is no
<code>MessageChannel</code> object that represents this
channel.)</p></li>
</ol>
<hr>
<p>When the user agent is to <dfn>clone a port</dfn> <var
title="">original port</var>, with the clone being owned by <var
title="">owner</var>, it must run the following steps, which return
a new <code>MessagePort</code> object. These steps must be run
atomically.</p>
<ol>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by <var title="">owner</var>, and let <var title="">new
port</var> be that object.</p></li>
<li><p>Move all the events in the <span>port message queue</span>
of <var title="">original port</var> to the <span>port message
queue</span> of <var title="">new port</var>, if any, leaving the
<var title="">new port</var>'s <span>port message queue</span> in
its initial disabled state.</p></li>
<li>
<p>If the <var title="">original port</var> is entangled with
another port, then run these substeps:</p>
<ol>
<li><p>Let the <var title="">remote port</var> be the port with
which the <var title="">original port</var> is entangled.</p></li>
<li><p><span>Entangle</span> the <var title="">remote port</var>
and <var title="">new port</var> objects. The <var
title="">original port</var> object will be disentangled by this
process.</p></li>
</ol>
</li>
<li><p>Return <var title="">new port</var>. It is the
clone.</p></li>
</ol>
<hr>
<!-- v2-onclose
<p>The <dfn title="dom-MessagePort-active"><code>active</code></dfn>
attribute must return true if the port is entangled, and false
otherwise.</p>
<hr>
-->
<p>The <dfn
title="dom-MessagePort-postMessage"><code>postMessage()</code></dfn>
method, when called on a port <var title="">source port</var>, must
cause the user agent to run the following steps:</p>
<ol>
<li><p>Let <var title="">target port</var> be the port with which
<var title="">source port</var> is entangled, if any.</p></li>
<li><p>If the method was called with a second argument <var
title="">ports</var> and that argument isn't null, then, if any of
the entries in <var title="">ports</var> are null, if any
<code>MessagePort</code> object is listed in <var
title="">ports</var> more than once, if any of the
<code>MessagePort</code> objects listed in <var
title="">ports</var> have already been cloned once before, or if
any of the entries in <var title="">ports</var> are either the <var
title="">source port</var> or the <var title="">target port</var>
(if any), then throw an <code>INVALID_STATE_ERR</code>
exception.</p></li>
<li><p>If there is no <var title="">target port</var> (i.e. if <var
title="">source port</var> is not entangled), then abort these
steps.</p></li>
<!-- we don't raise an exception if there is no target port because
this can happen at a moment's notice. we don't return false because
if the port is _about_ to be closed, the message might not be
listened for anyway. -->
<li><p>Create an event that uses the <code>MessageEvent</code>
interface, with the name <code
title="event-message">message</code>, which does not bubble, is not
cancelable, and has no default action.</p></li>
<li><p>Let <var title="">message</var> be the method's first
argument.</p></li>
<li><p>Let <var title="">message clone</var> be the result of
obtaining a <span>structured clone</span> of <var
title="">message</var>. If this throws an exception, then throw
that exception and abort these steps.</p></li>
<li><p>Let the <code title="dom-MessageEvent-data">data</code>
attribute of the event have the value of <var title="">message
clone</var>.</p></li>
<li><p>If the method was called with a second argument <var
title="">ports</var> and that argument isn't null, then run the
following substeps:</p>
<ol>
<li>
<p>Let <var title="">new ports</var> be an empty array.</p>
<p>For each port in <var title="">ports</var> in turn,
obtain a new port by <span title="clone a port">cloning</span>
the port with the owner of the <var title="">target port</var>
as the owner of the clone, and append the clone to the <var
title="">new ports</var> array.</p>
<p class="note">If the original <var title="">ports</var>
array was empty, then the <var title="">new ports</var> array will
also be empty.</p>
</li>
<li><p>Let the <code
title="dom-MessageEvent-ports">ports</code>
attribute of the event be the <var title="">new ports</var>
array.</p></li>
</ol>
</li>
<li><p>Add the event to the <span>port message queue</span> of <var
title="">target port</var>.</p></li>
</ol>
<!--
<hr>
<p>The <dfn
title="dom-MessagePort-startConversation"><code>startConversation(<var
title="">message</var>)</code></dfn> method is a convenience method
that simplifies create a new <code>MessageChannel</code> and
invoking <code
title="dom-MessagePort-postMessage">postMessage()</code> with one of
the new ports. When invoked on a port <var title="">source
port</var>, it must run the following steps:</p>
<ol>
<li><p>Let <var title="">message</var> be the method's first
argument.</p></li>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by the <span>script's global object</span>, and let <var
title="">port1</var> be that object.</p></li>
<li><p>If the <var title="">source port</var> is not entangled with
another port, then return <var title="">port1</var> and abort these
steps.</p></li>
<!- - we don't raise an exception because this can happen moment's
notice. we don't return null because then we'd end up with
null derefs. better to just let the likely next postMessage call
fall on the floor. - ->
<li><p>Let <var title="">target port</var> be the port with which
<var title="">source port</var> is entangled.</p></li>
<li><p><span>Create a new <code>MessagePort</code> object</span>
owned by the owner of the <var title="">target port</var>, and let
<var title="">port2</var> be that object.</p></li>
<li><p><span>Entangle</span> the <var title="">port1</var> and <var
title="">port2</var> objects.</p></li>
<li><p>Create an event that uses the <code>MessageEvent</code>
interface, with the name <code
title="event-message">message</code>, which does not bubble, is not
cancelable, and has no default action.</p></li>
<li><p>Let the <code title="dom-MessageEvent-data">data</code>
attribute of the event have the value of <var
title="">message</var>, the method's first argument.</p></li>
<li><p>Let the <code
title="dom-MessageEvent-ports">ports</code> attribute
of the event be an array containing only <var
title="">port2</var>.</p></li>
<li><p>Return <var title="">port1</var> from the method, but
continue with these steps.</p></li>
<li><p>Add the event to the <span>port message queue</span> of <var
title="">target port</var>.</p></li>
</ol>
-->
<hr>
<p>The <dfn title="dom-MessagePort-start"><code>start()</code></dfn>
method must enable its port's <span>port message queue</span>, if it
is not already enabled.</p>
<p>When a port's <span>port message queue</span> is enabled, the
<span>event loop</span> must use it as one of its <span title="task
source">task sources</span>.</p>
<p class="note">If the <code>Document</code> of the port's event
listeners' <span title="script's global object">global object</span>
is not <span>fully active</span>, then the messages are lost.</p>
<!-- because of the jump-to-entry-point algorithm first step -->
<hr>
<p>The <dfn title="dom-MessagePort-close"><code>close()</code></dfn>
method, when called on a port <var title="">local port</var> that is
entangled with another port, must cause the user agents to
disentangle the two ports. If the method is called on a port that is
not entangled, then the method must do nothing.</p>
<hr>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as IDL attributes, by
all objects implementing the <code>MessagePort</code> interface:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-MessagePort-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
</table>
<p>The first time a <code>MessagePort</code> object's <code
title="handler-MessagePort-onmessage">onmessage</code> IDL attribute
is set, the port's <span>port message queue</span> must be enabled,
as if the <code title="dom-MessagePort-start">start()</code> method
had been called.</p>
</div>
<h5>Ports and garbage collection</h5>
<div class="impl">
<p>When a <code>MessagePort</code> object <var title="">o</var> is
entangled, user agents must either act as if <var title="">o</var>'s
entangled <code>MessagePort</code> object has a strong reference to
<var title="">o</var>, or as if <var title="">o</var>'s owner has a
strong reference to <var title="">o</var>.</p>
<div class="note">
<p>Thus, a message port can be received, given an event listener,
and then forgotten, and so long as that event listener could
receive a message, the channel will be maintained.</p>
<p>Of course, if this was to occur on both sides of the channel,
then both ports could be garbage collected, since they would not be
reachable from live code, despite having a strong reference to each
other.</p>
</div>
<p>Furthermore, a <code>MessagePort</code> object must not be
garbage collected while there exists a message in a <span>task
queue</span> that is to be dispatched on that
<code>MessagePort</code> object, or while the
<code>MessagePort</code> object's <span>port message queue</span> is
open and there exists a <code title="event-message">message</code>
event in that queue.</p>
<!-- we might not need to explicitly say the first part if DOM
Events is fixed to say that events on a task queue prevent GC -->
<!-- ports in the ports attribute of a MessageEvent that isn't
dispatched yet are safe because the MessageEvent is safe -->
</div>
<p class="note">Authors are strongly encouraged to explicitly close
<code>MessagePort</code> objects to disentangle them, so that their
resources can be recollected. Creating many <code>MessagePort</code>
objects and discarding them without closing them can lead to high
memory usage.</p>
<h2 id="syntax"><dfn>The HTML syntax</dfn></h2>
<p class="note">This section only describes the rules for
<code>text/html</code> resources. Rules for XML resources are
discussed in the section below entitled "<span>The XHTML
syntax</span>".</p>
<h3 id="writing">Writing HTML documents</h3>
<div class="impl">
<p><i>This section only applies to documents, authoring tools, and
markup generators. In particular, it does not apply to conformance
checkers; conformance checkers must use the requirements given in
the next section ("parsing HTML documents").</i></p>
</div>
<p>Documents must consist of the following parts, in the given
order:</p>
<ol>
<li>Optionally, a single U+FEFF BYTE ORDER MARK (BOM) character.</li>
<li>Any number of <span title="syntax-comments">comments</span> and
<span title="space character">space characters</span>.</li>
<li>A <span title="syntax-doctype">DOCTYPE</span>.
<li>Any number of <span title="syntax-comments">comments</span> and
<span title="space character">space characters</span>.</li>
<li>The root element, in the form of an <code>html</code> <span
title="syntax-elements">element</span>.</li>
<li>Any number of <span title="syntax-comments">comments</span> and
<span title="space character">space characters</span>.</li>
</ol>
<p>The various types of content mentioned above are described in the
next few sections.</p>
<p>In addition, there are some restrictions on how <span
title="character encoding declaration">character encoding
declarations</span> are to be serialized, as discussed in the
section on that topic.</p>
<div class="note">
<p>Space characters before the root <code>html</code> element, and
space characters at the start of the <code>html</code> element and
before the <code>head</code> element, will be dropped when the
document is parsed; space characters <em>after</em> the root
<code>html</code> element will be parsed as if they were at the end
of the <code>body</code> element. Thus, space characters around the
root element do not round-trip.</p>
<p>It is suggested that newlines be inserted after the DOCTYPE,
after any comments that are before the root element, after the
<code>html</code> element's start tag (if it is not <span
title="syntax-tag-omission">omitted</span>), and after any comments
that are inside the <code>html</code> element but before the
<code>head</code> element.</p>
</div>
<p>Many strings in the HTML syntax (e.g. the names of elements and
their attributes) are case-insensitive, but only for characters in
the ranges U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL
LETTER Z) and U+0061 to U+007A (LATIN SMALL LETTER A to LATIN SMALL
LETTER Z). For convenience, in this section this is just referred to
as "case-insensitive".</p>
<h4>The DOCTYPE</h4>
<p>A <dfn title="syntax-doctype">DOCTYPE</dfn> is a mostly useless,
but required, header.</p>
<p class="note">DOCTYPEs are required for legacy reasons. When
omitted, browsers tend to use a different rendering mode that is
incompatible with some specifications. Including the DOCTYPE in a
document ensures that the browser makes a best-effort attempt at
following the relevant specifications.</p>
<p>A DOCTYPE must consist of the following characters, in this
order:</p>
<ol class="brief">
<li>A U+003C LESS-THAN SIGN character (<).</li>
<li>A U+0021 EXCLAMATION MARK character (!).</li>
<li>A string that is an <span>ASCII case-insensitive</span> match for the string "<code title="">DOCTYPE</code>".</li>
<li>One or more <span title="space character">space characters</span>.</li>
<li>A string that is an <span>ASCII case-insensitive</span> match for the string "<code title="">HTML</code>".</li>
<li>Optionally, a <span>DOCTYPE legacy string</span> (defined below).</li>
<li>Zero or more <span title="space character">space characters</span>.</li>
<li>A U+003E GREATER-THAN SIGN character (>).</li>
</ol>
<p class="note">In other words, <code><!DOCTYPE HTML></code>,
case-insensitively.</p>
<p>For the purposes of HTML generators that cannot output HTML
markup with the short DOCTYPE "<code title=""><!DOCTYPE
HTML></code>", a <dfn>DOCTYPE legacy string</dfn> may be inserted
into the DOCTYPE (in the position defined above). This string must
consist of:</p>
<ol class="brief">
<li>One or more <span title="space character">space characters</span>.</li>
<li>A string that is an <span>ASCII case-insensitive</span> match for the string "<code title="">SYSTEM</code>".</li>
<li>One or more <span title="space character">space characters</span>.</li>
<li>A U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (the <i>quote mark</i>).</li>
<li>The literal string "<code>about:legacy-compat</code>".</li>
<li>A matching U+0022 QUOTATION MARK or U+0027 APOSTROPHE character (i.e. the same character as in the earlier step marked <i>quote mark</i>).</li>
</ol>
<p class="note">In other words, <code><!DOCTYPE HTML SYSTEM
"about:legacy-compat"></code> or <code><!DOCTYPE HTML SYSTEM
'about:legacy-compat'></code>, case-insensitively except for the bit
in quotes.</p>
<p>The <span>DOCTYPE legacy string</span> should not be used unless
the document is generated from a system that cannot output the
shorter string.</p>
<h4>Elements</h4>
<p>There are five different kinds of <dfn
title="syntax-elements">elements</dfn>: <span>void elements</span>,
<span>raw text elements</span>, <span>RCDATA elements</span>,
<span>foreign elements</span>, and <span>normal elements</span>.</p>
<dl>
<dt><dfn>Void elements</dfn></dt>
<dd><code>area</code>, <code>base</code>, <code>br</code>,
<code>col</code>, <code>command</code>, <code>embed</code>,
<code>hr</code>, <code>img</code>, <code>input</code>,
<code>keygen</code>, <code>link</code>, <code>meta</code>,
<code>param</code>, <code>source</code></dd>
<dt><dfn>Raw text elements</dfn></dt>
<dd><code>script</code>, <code>style</code></dd> <!-- iframe and
noscript don't count as raw text for syntax purposes -->
<dt><dfn>RCDATA elements</dfn></dt>
<dd><code>textarea</code>, <code>title</code></dd>
<dt><dfn>Foreign elements</dfn></dt>
<dd>Elements from the <span>MathML namespace</span>
and the <span>SVG namespace</span>.</dd>
<dt><dfn>Normal elements</dfn></dt>
<dd>All other allowed <span>HTML elements</span> are normal
elements.</dd>
</dl>
<p><dfn title="syntax-tags">Tags</dfn> are used to delimit the start
and end of elements in the markup. <span title="raw text
elements">Raw text</span>, <span title="RCDATA
elements">RCDATA</span>, and <span title="normal
elements">normal</span> elements have a <span
title="syntax-start-tag">start tag</span> to indicate where they
begin, and an <span title="syntax-end-tag">end tag</span> to
indicate where they end. The start and end tags of certain
<span>normal elements</span> can be <span
title="syntax-tag-omission">omitted</span>, as described
later. Those that cannot be omitted must not be omitted. <span>Void
elements</span> only have a start tag; end tags must not be
specified for <span>void elements</span>. <span>Foreign
elements</span> must either have a start tag and an end tag, or a
start tag that is marked as self-closing, in which case they must
not have an end tag.</p>
<p>The contents of the element must be placed between just after the
start tag (which <span title="syntax-tag-omission">might be implied,
in certain cases</span>) and just before the end tag (which again,
<span title="syntax-tag-omission">might be implied in certain
cases</span>). The exact allowed contents of each individual element
depends on the content model of that element, as described earlier
in this specification. Elements must not contain content that their
content model disallows. In addition to the restrictions placed on
the contents by those content models, however, the five types of
elements have additional <em>syntactic</em> requirements.</p>
<p><span>Void elements</span> can't have any contents (since there's
no end tag, no content can be put between the start tag and the end
tag).</p>
<p><span>Raw text elements</span> can have <span
title="syntax-text">text</span>, though it has <a
href="#cdata-rcdata-restrictions">restrictions</a> described
below.</p>
<p><span>RCDATA elements</span> can have <span
title="syntax-text">text</span> and <span
title="syntax-charref">character references</span>, but the text
must not contain an <span
title="syntax-ambiguous-ampersand">ambiguous ampersand</span>.
There are also <a href="#cdata-rcdata-restrictions">further
restrictions</a> described below.</p>
<p><span>Foreign elements</span> whose start tag is marked as
self-closing can't have any contents (since, again, as there's no
end tag, no content can be put between the start tag and the end
tag). <span>Foreign elements</span> whose start tag is <em>not</em>
marked as self-closing can have <span
title="syntax-text">text</span>, <span
title="syntax-charref">character references</span>, <span
title="syntax-cdata">CDATA sections</span>, other <span
title="syntax-elements">elements</span>, and <span
title="syntax-comments">comments</span>, but the text must not
contain the character U+003C LESS-THAN SIGN (<) or an <span
title="syntax-ambiguous-ampersand">ambiguous ampersand</span>.</p>
<div class="note">
<p>The HTML syntax does not support namespace
declarations, even in <span>foreign elements</span>.</p>
<p>For instance, consider the following HTML fragment:</p>
<pre><p>
<svg>
<metadata>
<!-- this is invalid -->
<cdr:license xmlns:cdr="http://www.example.com/cdr/metadata" name="MIT"/>
</metadata>
</svg>
</p></pre>
<p>The innermost element, <code title="">cdr:license</code>, is
actually in the SVG namespace, as the "<code
title="">xmlns:cdr</code>" attribute has no effect (unlike in
XML). In fact, as the comment in the fragment above says, the
fragment is actually non-conforming. This is because the SVG
specification does not define any elements called "<code
title="">cdr:license</code>" in the SVG namespace.</p>
</div>
<p><span>Normal elements</span> can have <span
title="syntax-text">text</span>, <span
title="syntax-charref">character references</span>, other <span
title="syntax-elements">elements</span>, and <span
title="syntax-comments">comments</span>, but the text must not
contain the character U+003C LESS-THAN SIGN (<) or an <span
title="syntax-ambiguous-ampersand">ambiguous ampersand</span>. Some
<span>normal elements</span> also have <a
href="#element-restrictions">yet more restrictions</a> on what
content they are allowed to hold, beyond the restrictions imposed by
the content model and those described in this paragraph. Those
restrictions are described below.</p>
<p>Tags contain a <dfn title="syntax-tag-name">tag name</dfn>,
giving the element's name. HTML elements all have names that only
use characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT
NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER
Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER
Z. In the HTML syntax, tag names, even those for <span>foreign
elements</span>, may be written with any mix of lower- and uppercase
letters that, when converted to all-lowercase, matches the element's
tag name; tag names are case-insensitive.</p>
<h5>Start tags</h5>
<p><dfn title="syntax-start-tag">Start tags</dfn> must have the
following format:</p>
<ol>
<li>The first character of a start tag must be a U+003C LESS-THAN
SIGN character (<).</li>
<li>The next few characters of a start tag must be the element's
<span title="syntax-tag-name">tag name</span>.</li>
<li>If there are to be any attributes in the next step, there must
first be one or more <span title="space character">space
characters</span>.</li>
<li>Then, the start tag may have a number of attributes, the <span
title="syntax-attributes">syntax for which</span> is described
below. Attributes may be separated from each other by one or more
<span title="space character">space characters</span>.</li>
<li>After the attributes, there may be one or more <span
title="space character">space characters</span>. (Some attributes
are required to be followed by a space. See the <span
title="syntax-attributes">attributes section</span> below.)</li>
<li>Then, if the element is one of the <span>void elements</span>,
or if the element is a <span title="foreign elements">foreign
element</span>, then there may be a single U+002F SOLIDUS character
(/). This character has no effect on <span>void elements</span>,
but on <span>foreign elements</span> it marks the start tag as
self-closing.</li>
<li>Finally, start tags must be closed by a U+003E GREATER-THAN
SIGN character (>).</li>
</ol>
<h5>End tags</h5>
<p><dfn title="syntax-end-tag">End tags</dfn> must have the
following format:</p>
<ol>
<li>The first character of an end tag must be a U+003C LESS-THAN
SIGN character (<).</li>
<li>The second character of an end tag must be a U+002F SOLIDUS
character (/).</li>
<li>The next few characters of an end tag must be the element's
<span title="syntax-tag-name">tag name</span>.</li>
<li>After the tag name, there may be one or more <span title="space
character">space characters</span>.</li>
<li>Finally, end tags must be closed by a U+003E GREATER-THAN SIGN
character (>).</li>
</ol>
<h5>Attributes</h5>
<p><dfn title="syntax-attributes">Attributes</dfn> for an element
are expressed inside the element's start tag.</p>
<p>Attributes have a name and a value. <dfn
title="syntax-attribute-name">Attribute names</dfn> must consist of
one or more characters other than the <span title="space
character">space characters</span>, U+0000 NULL, U+0022 QUOTATION
MARK ("), U+0027 APOSTROPHE ('), U+003E GREATER-THAN SIGN
(>), U+002F SOLIDUS (/), and U+003D EQUALS SIGN (=) characters,
the control characters, and any characters that are not defined by
Unicode. In the HTML syntax, attribute names, even those for
<span>foreign elements</span>, may be written with any mix of lower-
and uppercase letters that are an <span>ASCII
case-insensitive</span> match for the attribute's name.</p>
<p><dfn title="syntax-attribute-value">Attribute values</dfn> are a
mixture of <span title="syntax-text">text</span> and <span
title="syntax-charref">character references</span>, except with the
additional restriction that the text cannot contain an <span
title="syntax-ambiguous-ampersand">ambiguous ampersand</span>.</p>
<p>Attributes can be specified in four different ways:</p>
<dl>
<dt>Empty attribute syntax</dt>
<dd>
<p>Just the <span title="syntax-attribute-name">attribute
name</span>.</p>
<div class="example">
<p>In the following example, the <code
title="attr-fe-disabled">disabled</code> attribute is given with
the empty attribute syntax:</p>
<pre><input <em>disabled</em>></pre>
</div>
<p>If an attribute using the empty attribute syntax is to be
followed by another attribute, then there must be a <span>space
character</span> separating the two.</p>
</dd>
<dt id="unquoted">Unquoted attribute value syntax</dt>
<dd>
<p>The <span title="syntax-attribute-name">attribute name</span>,
followed by zero or more <span title="space character">space
characters</span>, followed by a single U+003D EQUALS SIGN
character, followed by zero or more <span title="space
character">space characters</span>, followed by the <span
title="syntax-attribute-value">attribute value</span>, which, in
addition to the requirements given above for attribute values,
must not contain any literal <span title="space character">space
characters</span>, any U+0022 QUOTATION MARK characters ("),
U+0027 APOSTROPHE characters ('), U+003D EQUALS SIGN
characters (=), U+003C LESS-THAN SIGN characters (<), U+003E
GREATER-THAN SIGN characters (>), or U+0060 GRAVE ACCENT
characters (`), and must not be the empty string.</p>
<!-- The ` character is in this list on a temporary basis, waiting
for IE to fix it's parsing bug whereby it treats ` as an
attribute value delimiter. Otherwise, escaping software that
tries to be clever and not use quotes when it doesn't need to
could be tricked by an attacker.
Posit a site that allows the user to input text that is used
verbatim in two attributes, such that the user can set the
first attribute's value to:
`
...and the second to:
` onload='...payload...' end=x
...with the assumption that the site is going to not quote
the first one, and quote the second one with double quotes:
<body title=` class="` onload='...payload...' end=x">
In IE, this is treated as:
<body title=' class="'
onload='...payload...'
end='x"'>
-->
<div class="example">
<p>In the following example, the <code
title="attr-input-value">value</code> attribute is given
with the unquoted attribute value syntax:</p>
<pre><input <em>value=yes</em>></pre>
</div>
<p>If an attribute using the unquoted attribute syntax is to be
followed by another attribute or by the optional U+002F SOLIDUS
character (/) allowed in step 6 of the <span
title="syntax-start-tag">start tag</span> syntax above, then there
must be a <span>space character</span> separating the two.</p>
</dd>
<dt>Single-quoted attribute value syntax</dt>
<dd>
<p>The <span title="syntax-attribute-name">attribute name</span>,
followed by zero or more <span title="space character">space
characters</span>, followed by a single U+003D EQUALS SIGN
character, followed by zero or more <span title="space
character">space characters</span>, followed by a single U+0027
APOSTROPHE character ('), followed by the <span
title="syntax-attribute-value">attribute value</span>, which, in
addition to the requirements given above for attribute values,
must not contain any literal U+0027 APOSTROPHE characters ('), and
finally followed by a second single U+0027 APOSTROPHE character
(').</p>
<div class="example">
<p>In the following example, the <code
title="attr-input-type">type</code> attribute is given with the
single-quoted attribute value syntax:</p>
<pre><input <em>type='checkbox'</em>></pre>
</div>
<p>If an attribute using the single-quoted attribute syntax is to
be followed by another attribute, then there must be a <span>space
character</span> separating the two.</p>
</dd>
<dt>Double-quoted attribute value syntax</dt>
<dd>
<p>The <span title="syntax-attribute-name">attribute name</span>,
followed by zero or more <span title="space character">space
characters</span>, followed by a single U+003D EQUALS SIGN
character, followed by zero or more <span title="space
character">space characters</span>, followed by a single U+0022
QUOTATION MARK character ("), followed by the <span
title="syntax-attribute-value">attribute value</span>, which, in
addition to the requirements given above for attribute values,
must not contain any literal U+0022 QUOTATION MARK characters ("),
and finally followed by a second single U+0022 QUOTATION MARK
character (").</p>
<div class="example">
<p>In the following example, the <code
title="attr-fe-name">name</code> attribute is given with the
double-quoted attribute value syntax:</p>
<pre><input <em>name="be evil"</em>></pre>
</div>
<p>If an attribute using the double-quoted attribute syntax is to
be followed by another attribute, then there must be a <span>space
character</span> separating the two.</p>
</dd>
</dl>
<p>There must never be two or more attributes on the same start tag
whose names are an <span>ASCII case-insensitive</span> match for
each other.</p>
<hr>
<p>When a <span title="foreign elements">foreign element</span> has
one of the namespaced attributes given by the local name and
namespace of the first and second cells of a row from the following
table, it must be written using the name given by the third cell
from the same row.</p>
<table>
<thead>
<tr> <th> Local name <th> Namespace <th> Attribute name
<tbody>
<tr> <td> <code title="">actuate</code> <td> <span>XLink namespace</span> <td> <code title="">xlink:actuate</code>
<tr> <td> <code title="">arcrole</code> <td> <span>XLink namespace</span> <td> <code title="">xlink:arcrole</code>
<tr> <td> <code title="">href</code> <td> <span>XLink namespace</span> <td> <code title="">xlink:href</code>
<tr> <td> <code title="">role</code> <td> <span>XLink namespace</span> <td> <code title="">xlink:role</code>
<tr> <td> <code title="">show</code> <td> <span>XLink namespace</span> <td> <code title="">xlink:show</code>
<tr> <td> <code title="">title</code> <td> <span>XLink namespace</span> <td> <code title="">xlink:title</code>
<tr> <td> <code title="">type</code> <td> <span>XLink namespace</span> <td> <code title="">xlink:type</code>
<tr> <td> <code title="">base</code> <td> <span>XML namespace</span> <!-- attr-xml-base --> <td> <code title="">xml:base</code>
<tr> <td> <code title="">lang</code> <td> <span>XML namespace</span> <td> <code title="">xml:lang</code>
<tr> <td> <code title="">space</code> <td> <span>XML namespace</span> <td> <code title="">xml:space</code>
<tr> <td> <code title="">xmlns</code> <td> <span>XMLNS namespace</span> <td> <code title="">xmlns</code>
<tr> <td> <code title="">xlink</code> <td> <span>XMLNS namespace</span> <td> <code title="">xmlns:xlink</code>
</table>
<p>No other namespaced attribute can be expressed in <span>the
HTML syntax</span>.</p>
<h5>Optional tags</h5>
<p>Certain tags can be <dfn
title="syntax-tag-omission">omitted</dfn>.</p>
<p class="note">Omitting an element's <span
title="syntax-start-tag">start tag</span> does not mean the element
is not present; it is implied, but it is still there. An HTML
document always has a root <code>html</code> element, even if the
string <code title=""><html></code> doesn't appear anywhere in
the markup.</p>
<!-- <html> -->
<p>An <code>html</code> element's <span
title="syntax-start-tag">start tag</span> may be omitted if the
first thing inside the <code>html</code> element is not a <span
title="syntax-comments">comment</span>.</p>
<!-- </html> -->
<p>An <code>html</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>html</code> element is not
immediately followed by a <span
title="syntax-comments">comment</span>.</p>
<!-- <head> -->
<p>A <code>head</code> element's <span
title="syntax-start-tag">start tag</span> may be omitted <!--if the
element is empty, or--> if the first thing inside the
<code>head</code> element is an element.</p>
<!-- </head> -->
<p>A <code>head</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>head</code> element is not
immediately followed by a <span>space character</span> or a <span
title="syntax-comments">comment</span>.</p>
<!-- <body> -->
<p>A <code>body</code> element's <span
title="syntax-start-tag">start tag</span> may be omitted if the
element is empty, or if the first thing inside the <code>body</code>
element is not a <span>space character</span> or a <span
title="syntax-comments">comment</span>, except if the first thing
inside the <code>body</code> element is a <code>script</code> or
<code>style</code> element. <!-- Note that even if the </head> end
tag is present, the parser makes <style> and <script> elements
between </head> and <body> end up in the <head> instead of implying
the <body> --></p>
<!-- </body> -->
<p>A <code>body</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>body</code> element is not
immediately followed by a <span
title="syntax-comments">comment</span>.</p>
<!-- </li> -->
<p>A <code>li</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>li</code> element is
immediately followed by another <code>li</code> element or if there
is no more content in the parent element.</p>
<!-- </dt> -->
<p>A <code>dt</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>dt</code> element is
immediately followed by another <code>dt</code> element or a
<code>dd</code> element.</p>
<!-- </dd> -->
<p>A <code>dd</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>dd</code> element is
immediately followed by another <code>dd</code> element or a
<code>dt</code> element, or if there is no more content in the
parent element.</p>
<!-- </p> -->
<p>A <code>p</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>p</code> element is
immediately followed by an <code>address</code>,
<code>article</code>, <code>aside</code>, <code>blockquote</code>,
<!--v2DATAGRID <code>datagrid</code>,--> <code>dir</code>,
<code>div</code>, <code>dl</code>, <code>fieldset</code>,
<code>footer</code>, <code>form</code>, <code>h1</code>,
<code>h2</code>, <code>h3</code>, <code>h4</code>, <code>h5</code>,
<code>h6</code>, <code>header</code>, <code>hgroup</code>,
<code>hr</code>, <code>menu</code>, <code>nav</code>,
<code>ol</code>, <code>p</code>, <code>pre</code>,
<code>section</code>, <code>table</code>, or <code>ul</code>,
element, or if there is no more content in the parent element and
the parent element is not an <code>a</code> element.</p>
<!-- </rt> -->
<p>An <code>rt</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>rt</code> element is
immediately followed by an <code>rt</code> or <code>rp</code>
element, or if there is no more content in the parent element.</p>
<!-- </rp> -->
<p>An <code>rp</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>rp</code> element is
immediately followed by an <code>rt</code> or <code>rp</code>
element, or if there is no more content in the parent element.</p>
<!-- </optgroup> (the text assumes <optgroup> can only be inside a
<select>; commented out text below can handle the non-<select> case
if we ever allow it) -->
<p>An <code>optgroup</code> element's <span
title="syntax-end-tag">end tag</span> may be omitted if the
<code>optgroup</code> element <!--has an ancestor
<code>select</code> element and--> is immediately followed by
another <code>optgroup</code> element, or if <!--all of the elements
that are ancestors of the <code>optgroup</code> element, up to and
including the first ancestor element that is not an
<code>optgroup</code> element, have no more content--> there is no
more content in the parent element.</p>
<!-- so e.g. the max number of </optgroup>s are omitted here:
<select><optgroup></select>
<p id=x><optgroup></optgroup>x</p>
<p id=x><optgroup><optgroup></optgroup></optgroup>x</p>
<p><optgroup id=x><optgroup></optgroup>x</p>
<p><optgroup><optgroup id=x>x</p>
-->
<!-- </option> -->
<p>An <code>option</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>option</code> element is
immediately followed by another <code>option</code> element, or if
it is immediately followed by an <code>optgroup</code> element, or
if there is no more content in the parent element.</p>
<!-- <colgroup> -->
<p>A <code>colgroup</code> element's <span
title="syntax-start-tag">start tag</span> may be omitted if the
first thing inside the <code>colgroup</code> element is a
<code>col</code> element, and if the element is not immediately
preceded by another <code>colgroup</code> element whose <span
title="syntax-end-tag">end tag</span> has been omitted. (It can't be
omitted if the element is empty.)</p>
<!-- </colgroup> -->
<p>A <code>colgroup</code> element's <span
title="syntax-end-tag">end tag</span> may be omitted if the
<code>colgroup</code> element is not immediately followed by a
<span>space character</span> or a <span
title="syntax-comments">comment</span>.</p>
<!-- </thead> -->
<p>A <code>thead</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>thead</code> element is
immediately followed by a <code>tbody</code> or <code>tfoot</code>
element.</p>
<!-- <tbody> -->
<p>A <code>tbody</code> element's <span
title="syntax-start-tag">start tag</span> may be omitted if the
first thing inside the <code>tbody</code> element is a
<code>tr</code> element, and if the element is not immediately
preceded by a <code>tbody</code>, <code>thead</code>, or
<code>tfoot</code> element whose <span title="syntax-end-tag">end
tag</span> has been omitted. (It can't be omitted if the element is
empty.)</p>
<!-- </tbody> -->
<p>A <code>tbody</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>tbody</code> element is
immediately followed by a <code>tbody</code> or <code>tfoot</code>
element, or if there is no more content in the parent element.</p>
<!-- </tfoot> -->
<p>A <code>tfoot</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>tfoot</code> element is
immediately followed by a <code>tbody</code> element, or if there is
no more content in the parent element.</p>
<!-- </tr> -->
<p>A <code>tr</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>tr</code> element is
immediately followed by another <code>tr</code> element, or if there
is no more content in the parent element.</p>
<!-- </td> -->
<p>A <code>td</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>td</code> element is
immediately followed by a <code>td</code> or <code>th</code>
element, or if there is no more content in the parent element.</p>
<!-- </th> -->
<p>A <code>th</code> element's <span title="syntax-end-tag">end
tag</span> may be omitted if the <code>th</code> element is
immediately followed by a <code>td</code> or <code>th</code>
element, or if there is no more content in the parent element.</p>
<p><strong>However</strong>, a <span title="syntax-start-tag">start
tag</span> must never be omitted if it has any attributes.</p>
<h5 id="element-restrictions">Restrictions on content models</h5>
<p>For historical reasons, certain elements have extra restrictions
beyond even the restrictions given by their content model.</p>
<p>A <code>table</code> element must not contain <code>tr</code>
elements, even though these elements are technically allowed inside
<code>table</code> elements according to the content models
described in this specification. (If a <code>tr</code> element is
put inside a <code>table</code> in the markup, it will in fact imply
a <code>tbody</code> start tag before it.)</p>
<p>A single <span title="syntax-newlines">newline</span> may be
placed immediately after the <span title="syntax-start-tag">start
tag</span> of <code>pre</code> and <code>textarea</code>
elements. This does not affect the processing of the element. The
otherwise optional <span title="syntax-newlines">newline</span>
<em>must</em> be included if the element's contents themselves start
with a <span title="syntax-newlines">newline</span> (because
otherwise the leading newline in the contents would be treated like
the optional newline, and ignored).</p>
<div class="example">
<p>The following two <code>pre</code> blocks are equivalent:</p>
<pre><pre>Hello</pre></pre>
<pre><pre><br>Hello</pre></pre>
</div>
<h5 id="cdata-rcdata-restrictions">Restrictions on the contents of raw text and RCDATA elements</h5>
<p>The text in <span title="raw text elements">raw text</span> and
<span title="RCDATA elements">RCDATAs</span> element must not
contain any occurrences of the string "<code title=""></</code>"
(U+003C LESS-THAN SIGN, U+002F SOLIDUS) followed by characters that
case-insensitively match the tag name of the element followed by one
of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM
FEED (FF), U+000D CARRIAGE RETURN (CR), U+0020 SPACE, U+003E
GREATER-THAN SIGN (>), or U+002F SOLIDUS (/).</p>
<h4>Text</h4>
<p><dfn title="syntax-text">Text</dfn> is allowed inside elements,
attributes, and comments. Text must consist of Unicode characters.
Text must not contain U+0000 characters. Text must not contain
permanently undefined Unicode characters (noncharacters). Text must
not contain control characters other than <span title="space
character">space characters</span>. Extra constraints are placed on
what is and what is not allowed in text based on where the text is
to be put, as described in the other sections.</p>
<h5>Newlines</h5>
<p><dfn title="syntax-newlines">Newlines</dfn> in HTML may be
represented either as U+000D CARRIAGE RETURN (CR) characters, U+000A
LINE FEED (LF) characters, or pairs of U+000D CARRIAGE RETURN (CR),
U+000A LINE FEED (LF) characters in that order.</p>
<h4>Character references</h4>
<p>In certain cases described in other sections, <span
title="syntax-text">text</span> may be mixed with <dfn
title="syntax-charref">character references</dfn>. These can be used
to escape characters that couldn't otherwise legally be included in
<span title="syntax-text">text</span>.</p>
<p>Character references must start with a U+0026 AMPERSAND character
(&). Following this, there are three possible kinds of character
references:</p>
<dl>
<dt>Named character references</dt>
<dd>The ampersand must be followed by one of the names given in the
<span>named character references</span> section, using the same
case. The name must be one that is terminated by a U+003B SEMICOLON
character (;).</dd>
<dt>Decimal numeric character reference</dt>
<dd>The ampersand must be followed by a U+0023 NUMBER SIGN
character (#), followed by one or more digits in the range U+0030
DIGIT ZERO (0) to U+0039 DIGIT NINE (9), representing a base-ten
integer that corresponds to a Unicode code point that is allowed
according to the definition below. The digits must then be followed
by a U+003B SEMICOLON character (;).</dd>
<dt>Hexadecimal numeric character reference</dt>
<dd>The ampersand must be followed by a U+0023 NUMBER SIGN
character (#), which must be followed by either a U+0078 LATIN
SMALL LETTER X character (x) or a U+0058 LATIN CAPITAL LETTER X
character (X), which must then be followed by one or more digits in
the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061
LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, and U+0041
LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F,
representing a base-sixteen integer that corresponds to a Unicode
code point that is allowed according to the definition below. The
digits must then be followed by a U+003B SEMICOLON character
(;).</dd>
</dl>
<p>The numeric character reference forms described above are allowed
to reference any Unicode code point other than U+0000, permanently
undefined Unicode characters (noncharacters), and control characters
other than <span title="space character">space
characters</span>.</p>
<p>An <dfn title="syntax-ambiguous-ampersand">ambiguous
ampersand</dfn> is a U+0026 AMPERSAND character (&) that is
followed by some <span title="syntax-text">text</span> other than a
<span>space character</span>, a U+003C LESS-THAN SIGN character
(<), or another U+0026 AMPERSAND character (&).</p>
<h4>CDATA sections</h4>
<p><dfn title="syntax-cdata">CDATA sections</dfn> must start with
the character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
MARK, U+005B LEFT SQUARE BRACKET, U+0043 LATIN CAPITAL LETTER C,
U+0044 LATIN CAPITAL LETTER D, U+0041 LATIN CAPITAL LETTER A, U+0054
LATIN CAPITAL LETTER T, U+0041 LATIN CAPITAL LETTER A, U+005B LEFT
SQUARE BRACKET (<code title=""><![CDATA[</code>). Following this
sequence, the CDATA section may have <span
title="syntax-text">text</span>, with the additional restriction
that the text must not contain the three character sequence U+005D
RIGHT SQUARE BRACKET, U+005D RIGHT SQUARE BRACKET, U+003E
GREATER-THAN SIGN (<code title="">]]></code>). Finally, the CDATA
section must be ended by the three character sequence U+005D RIGHT
SQUARE BRACKET, U+005D RIGHT SQUARE BRACKET, U+003E GREATER-THAN
SIGN (<code title="">]]></code>).</p>
<h4>Comments</h4>
<p><dfn title="syntax-comments">Comments</dfn> must start with the
four character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS (<code
title=""><!--</code>). Following this sequence, the comment may
have <span title="syntax-text">text</span>, with the additional
restriction that the text must not start with a single U+003E
GREATER-THAN SIGN character (>), nor start with a U+002D
HYPHEN-MINUS character (-) followed by a U+003E GREATER-THAN SIGN
(>) character, nor contain two consecutive U+002D HYPHEN-MINUS
characters (<code title="">--</code>), nor end with a U+002D
HYPHEN-MINUS character (-). Finally, the comment must be ended by
the three character sequence U+002D HYPHEN-MINUS, U+002D
HYPHEN-MINUS, U+003E GREATER-THAN SIGN (<code
title="">--></code>).</p>
<div class="impl">
<h3 id="parsing">Parsing HTML documents</h3>
<p><i>This section only applies to user agents, data mining tools,
and conformance checkers.</i></p>
<p class="note">The rules for parsing XML documents into DOM trees
are covered by the next section, entitled "<span>The XHTML
syntax</span>".</p>
<p>For <span>HTML documents</span>, user agents must use the parsing
rules described in this section to generate the DOM trees. Together,
these rules define what is referred to as the <dfn>HTML
parser</dfn>.</p>
<div class="note">
<p>While the HTML syntax described in this specification bears a
close resemblance to SGML and XML, it is a separate language with
its own parsing rules.</p>
<p>Some earlier versions of HTML (in particular from HTML2 to
HTML4) were based on SGML and used SGML parsing rules. However, few
(if any) web browsers ever implemented true SGML parsing for HTML
documents; the only user agents to strictly handle HTML as an SGML
application have historically been validators. The resulting
confusion — with validators claiming documents to have one
representation while widely deployed Web browsers interoperably
implemented a different representation — has wasted decades
of productivity. This version of HTML thus returns to a non-SGML
basis.</p>
<p>Authors interested in using SGML tools in their authoring
pipeline are encouraged to use XML tools and the XML serialization
of HTML.</p>
</div>
<p>This specification defines the parsing rules for HTML documents,
whether they are syntactically correct or not. Certain points in the
parsing algorithm are said to be <dfn title="parse error">parse
errors</dfn>. The error handling for parse errors is well-defined:
user agents must either act as described below when encountering
such problems, or must abort processing at the first error that they
encounter for which they do not wish to apply the rules described
below.</p>
<p>Conformance checkers must report at least one parse error
condition to the user if one or more parse error conditions exist in
the document and must not report parse error conditions if none
exist in the document. Conformance checkers may report more than one
parse error condition if more than one parse error condition exists
in the document. Conformance checkers are not required to recover
from parse errors.</p>
<p class="note">Parse errors are only errors with the
<em>syntax</em> of HTML. In addition to checking for parse errors,
conformance checkers will also verify that the document obeys all
the other conformance requirements described in this
specification.</p>
<p>For the purposes of conformance checkers, if a resource is
determined to be in <span>the HTML syntax</span>, then it is an
<span title="HTML documents">HTML document</span>.</p>
</div>
<div class="impl">
<h4>Overview of the parsing model</h4>
<p>The input to the HTML parsing process consists of a stream of
Unicode characters, which is passed through a
<span>tokenization</span> stage followed by a <span>tree
construction</span> stage. The output is a <code>Document</code>
object.</p>
<p class="note">Implementations that <a href="#non-scripted">do not
support scripting</a> do not have to actually create a DOM
<code>Document</code> object, but the DOM tree in such cases is
still used as the model for the rest of the specification.</p>
<p>In the common case, the data handled by the tokenization stage
comes from the network, but <span title="dynamic markup
insertion">it can also come from script</span>, e.g. using the <code
title="dom-document-write">document.write()</code> API.</p>
<p><img src="images/parsing-model-overview.png" alt=""></p>
<p id="nestedParsing">There is only one set of states for the
tokenizer stage and the tree construction stage, but the tree
construction stage is reentrant, meaning that while the tree
construction stage is handling one token, the tokenizer might be
resumed, causing further tokens to be emitted and processed before
the first token's processing is complete.</p>
<div class="example">
<p>In the following example, the tree construction stage will be
called upon to handle a "p" start tag token while handling the
"script" start tag token:</p>
<pre>...
<script>
document.write('<p>');
</script>
...</pre>
</div>
<p>To handle these cases, parsers have a <dfn>script nesting
level</dfn>, which must be initially set to zero, and a <dfn>parser
pause flag</dfn>, which must be initially set to false.</p>
</div>
<div class="impl">
<h4>The <dfn>input stream</dfn></h4>
<p>The stream of Unicode characters that comprises the input to the
tokenization stage will be initially seen by the user agent as a
stream of bytes (typically coming over the network or from the local
file system). The bytes encode the actual characters according to a
particular <em>character encoding</em>, which the user agent must
use to decode the bytes into characters.</p>
<p class="note">For XML documents, the algorithm user agents must
use to determine the character encoding is given by the XML
specification. This section does not apply to XML documents. <a
href="#refsXML">[XML]</a></p>
<h5>Determining the character encoding</h5>
<p>In some cases, it might be impractical to unambiguously determine
the encoding before parsing the document. Because of this, this
specification provides for a two-pass mechanism with an optional
pre-scan. Implementations are allowed, as described below, to apply
a simplified parsing algorithm to whatever bytes they have available
before beginning to parse the document. Then, the real parser is
started, using a tentative encoding derived from this pre-parse and
other out-of-band metadata. If, while the document is being loaded,
the user agent discovers an encoding declaration that conflicts with
this information, then the parser can get reinvoked to perform a
parse of the document with the real encoding.</p>
<p id="documentEncoding">User agents must use the following
algorithm (the <dfn>encoding sniffing algorithm</dfn>) to determine
the character encoding to use when decoding a document in the first
pass. This algorithm takes as input any out-of-band metadata
available to the user agent (e.g. the <span
title="Content-Type">Content-Type metadata</span> of the document)
and all the bytes available so far, and returns an encoding and a
<dfn title="concept-encoding-confidence">confidence</dfn>. The
confidence is either <i>tentative</i>, <i>certain</i>, or
<i>irrelevant</i>. The encoding used, and whether the confidence in
that encoding is <i>tentative</i> or <i>certain</i>, is <a
href="#meta-charset-during-parse">used during the parsing</a> to
determine whether to <span>change the encoding</span>. If no
encoding is necessary, e.g. because the parser is operating on a
stream of Unicode characters and doesn't have to use an encoding at
all, then the <span
title="concept-encoding-confidence">confidence</span> is
<i>irrelevant</i>.</p>
<ol>
<li><p>If the transport layer specifies an encoding, and it is
supported, return that encoding with the <span
title="concept-encoding-confidence">confidence</span>
<i>certain</i>, and abort these steps.</p></li>
<li><p>The user agent may wait for more bytes of the resource to be
available, either in this step or at any later step in this
algorithm. For instance, a user agent might wait 500ms or 512
bytes, whichever came first. In general preparsing the source to
find the encoding improves performance, as it reduces the need to
throw away the data structures used when parsing upon finding the
encoding information. However, if the user agent delays too long to
obtain data to determine the encoding, then the cost of the delay
could outweigh any performance improvements from the
preparse.</p></li>
<li><p>For each of the rows in the following table, starting with
the first one and going down, if there are as many or more bytes
available than the number of bytes in the first column, and the
first bytes of the file match the bytes given in the first column,
then return the encoding given in the cell in the second column of
that row, with the <span
title="concept-encoding-confidence">confidence</span>
<i>certain</i>, and abort these steps:</p>
<!-- this table is present in several forms in this file; keep them in sync -->
<table>
<thead>
<tr>
<th>Bytes in Hexadecimal
<th>Encoding
<tbody>
<!-- nobody uses this
<tr>
<td>00 00 FE FF
<td>UTF-32BE
<tr>
<td>FF FE 00 00
<td>UTF-32LE
-->
<tr>
<td>FE FF
<td>UTF-16BE
<tr>
<td>FF FE
<td>UTF-16LE
<tr>
<td>EF BB BF
<td>UTF-8
<!-- nobody uses this
<tr>
<td>DD 73 66 73
<td>UTF-EBCDIC
-->
</table>
<p class="note">This step looks for Unicode Byte Order Marks
(BOMs).</p></li>
<li><p>Otherwise, the user agent will have to search for explicit
character encoding information in the file itself. This should
proceed as follows:
<p>Let <var title="">position</var> be a pointer to a byte in the
input stream, initially pointing at the first byte. If at any
point during these substeps the user agent either runs out of
bytes or decides that scanning further bytes would not be
efficient, then skip to the next step of the overall character
encoding detection algorithm. User agents may decide that scanning
<em>any</em> bytes is not efficient, in which case these substeps
are entirely skipped.</p>
<p>Now, repeat the following "two" steps until the algorithm
aborts (either because user agent aborts, as described above, or
because a character encoding is found):</p>
<ol>
<li><p>If <var title="">position</var> points to:</p>
<dl class="switch">
<dt>A sequence of bytes starting with: 0x3C 0x21 0x2D 0x2D (ASCII '<!--')</dt>
<dd>
<p>Advance the <var title="">position</var> pointer so that it
points at the first 0x3E byte which is preceded by two 0x2D
bytes (i.e. at the end of an ASCII '-->' sequence) and comes
after the 0x3C byte that was found. (The two 0x2D bytes can be
the same as the those in the '<!--' sequence.)</p>
</dd>
<dt>A sequence of bytes starting with: 0x3C, 0x4D or 0x6D, 0x45 or 0x65, 0x54 or 0x74, 0x41 or 0x61, and finally one of 0x09, 0x0A, 0x0C, 0x0D, 0x20, 0x2F (case-insensitive ASCII '<meta' followed by a space or slash)</dt>
<dd>
<ol>
<li><p>Advance the <var title="">position</var> pointer so
that it points at the next 0x09, 0x0A, 0x0C, 0x0D, 0x20, or
0x2F byte (the one in sequence of characters matched
above).</p></li>
<li><p><span title="concept-get-attributes-when-sniffing">Get
an attribute</span> and its value. If no attribute was
sniffed, then skip this inner set of steps, and jump to the
second step in the overall "two step" algorithm.</p></li>
<li><p>If the attribute's name is neither "<code
title="">charset</code>" nor "<code title="">content</code>",
then return to step 2 in these inner steps.</p></li>
<li><p>If the attribute's name is "<code
title="">charset</code>", let <var title="">charset</var> be
the attribute's value, interpreted as a character
encoding.</p></li>
<li><p>Otherwise, the attribute's name is "<code
title="">content</code>": apply the <span>algorithm for
extracting an encoding from a Content-Type</span>, giving the
attribute's value as the string to parse. If an encoding is
returned, let <var title="">charset</var> be that
encoding. Otherwise, return to step 2 in these inner
steps.</p></li>
<li><p>If <var title="">charset</var> is a UTF-16 encoding,
change the value of <var title="">charset</var> to
UTF-8.</p></li>
<li><p>If <var title="">charset</var> is a supported
character encoding, then return the given encoding, with
<span title="concept-encoding-confidence">confidence</span>
<i>tentative</i>, and abort all these steps.</p></li>
<li><p>Otherwise, return to step 2 in these inner
steps.</p></li>
</ol>
</dd>
<dt>A sequence of bytes starting with a 0x3C byte (ASCII <), optionally a 0x2F byte (ASCII /), and finally a byte in the range 0x41-0x5A or 0x61-0x7A (an ASCII letter)</dt>
<dd>
<ol>
<li><p>Advance the <var title="">position</var> pointer so
that it points at the next 0x09 (ASCII TAB), 0x0A (ASCII LF),
0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x3E
(ASCII >) byte.</p></li>
<li><p>Repeatedly <span
title="concept-get-attributes-when-sniffing">get an
attribute</span> until no further attributes can be found,
then jump to the second step in the overall "two step"
algorithm.</p></li>
</ol>
</dd>
<dt>A sequence of bytes starting with: 0x3C 0x21 (ASCII '<!')</dt>
<dt>A sequence of bytes starting with: 0x3C 0x2F (ASCII '</')</dt>
<dt>A sequence of bytes starting with: 0x3C 0x3F (ASCII '<?')</dt>
<dd>
<p>Advance the <var title="">position</var> pointer so that it
points at the first 0x3E byte (ASCII >) that comes after the
0x3C byte that was found.</p>
</dd>
<dt>Any other byte</dt>
<dd>
<p>Do nothing with that byte.</p>
</dd>
</dl>
</li>
<li>Move <var title="">position</var> so it points at the next
byte in the input stream, and return to the first step of this
"two step" algorithm.</li>
</ol>
<p>When the above "two step" algorithm says to <dfn
title="concept-get-attributes-when-sniffing">get an
attribute</dfn>, it means doing this:</p>
<ol>
<li><p>If the byte at <var title="">position</var> is one of 0x09
(ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR),
0x20 (ASCII space), or 0x2F (ASCII /) then advance <var
title="">position</var> to the next byte and redo this
substep.</p></li>
<li><p>If the byte at <var title="">position</var> is 0x3E (ASCII
>), then abort the "get an attribute" algorithm. There isn't
one.</p></li>
<li><p>Otherwise, the byte at <var title="">position</var> is the
start of the attribute name. Let <var title="">attribute
name</var> and <var title="">attribute value</var> be the empty
string.</p></li>
<li><p><i>Attribute name</i>: Process the byte at <var
title="">position</var> as follows:</p>
<dl class="switch">
<dt>If it is 0x3D (ASCII =), and the <var title="">attribute
name</var> is longer than the empty string</dt>
<dd>Advance <var title="">position</var> to the next byte and
jump to the step below labeled <i>value</i>.</dd>
<dt>If it is 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII
FF), 0x0D (ASCII CR), or 0x20 (ASCII space)</dt>
<dd>Jump to the step below labeled <i>spaces</i>.</dd>
<dt>If it is 0x2F (ASCII /) or 0x3E (ASCII >)</dt>
<dd>Abort the "get an attribute" algorithm. The attribute's
name is the value of <var title="">attribute name</var>, its
value is the empty string.</dd>
<dt>If it is in the range 0x41 (ASCII A) to 0x5A (ASCII
Z)</dt>
<dd>Append the Unicode character with code point <span title=""><var
title="">b</var>+0x20</span> to <var title="">attribute
name</var> (where <var title="">b</var> is the value of the
byte at <var title="">position</var>).</dd>
<dt>Anything else</dt>
<dd>Append the Unicode character with the same code point as the
value of the byte at <var title="">position</var>) to <var
title="">attribute name</var>. (It doesn't actually matter how
bytes outside the ASCII range are handled here, since only
ASCII characters can contribute to the detection of a character
encoding.)</dd>
</dl>
</li>
<li><p>Advance <var title="">position</var> to the next byte and
return to the previous step.</p></li>
<li><p><i>Spaces</i>: If the byte at <var
title="">position</var> is one of 0x09 (ASCII TAB), 0x0A (ASCII
LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then
advance <var title="">position</var> to the next byte, then,
repeat this step.</p></li>
<li><p>If the byte at <var title="">position</var> is
<em>not</em> 0x3D (ASCII =), abort the "get an attribute"
algorithm. The attribute's name is the value of <var
title="">attribute name</var>, its value is the empty
string.</p></li>
<li><p>Advance <var title="">position</var> past the 0x3D (ASCII
=) byte.</p></li>
<li><p><i>Value:</i> If the byte at <var
title="">position</var> is one of 0x09 (ASCII TAB), 0x0A (ASCII
LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then
advance <var title="">position</var> to the next byte, then,
repeat this step.</p></li>
<li><p>Process the byte at <var title="">position</var> as
follows:</p>
<dl class="switch">
<dt>If it is 0x22 (ASCII ") or 0x27 (ASCII ')</dt>
<dd>
<ol>
<li>Let <var title="">b</var> be the value of the byte at
<var title="">position</var>.</li>
<li>Advance <var title="">position</var> to the next
byte.</li>
<li>If the value of the byte at <var title="">position</var>
is the value of <var title="">b</var>, then advance <var
title="">position</var> to the next byte and abort the "get
an attribute" algorithm. The attribute's name is the value of
<var title="">attribute name</var>, and its value is the
value of <var title="">attribute value</var>.</li>
<li>Otherwise, if the value of the byte at <var
title="">position</var> is in the range 0x41 (ASCII A) to
0x5A (ASCII Z), then append a Unicode character to <var
title="">attribute value</var> whose code point is 0x20 more
than the value of the byte at <var
title="">position</var>.</li>
<li>Otherwise, append a Unicode character to <var
title="">attribute value</var> whose code point is the same as
the value of the byte at <var title="">position</var>.</li>
<li>Return to the second step in these substeps.</li>
</ol>
</dd>
<dt>If it is 0x3E (ASCII >)</dt>
<dd>Abort the "get an attribute" algorithm. The attribute's
name is the value of <var title="">attribute name</var>, its
value is the empty string.</dd>
<dt>If it is in the range 0x41 (ASCII A) to 0x5A (ASCII
Z)</dt>
<dd>Append the Unicode character with code point <span title=""><var
title="">b</var>+0x20</span> to <var title="">attribute
value</var> (where <var title="">b</var> is the value of the
byte at <var title="">position</var>). Advance <var
title="">position</var> to the next byte.</dd>
<dt>Anything else</dt>
<dd>Append the Unicode character with the same code point as the
value of the byte at <var title="">position</var>) to <var
title="">attribute value</var>. Advance <var
title="">position</var> to the next byte.</dd>
</dl>
</li>
<li><p>Process the byte at <var title="">position</var> as
follows:</p>
<dl class="switch">
<dt>If it is 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII
FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x3E (ASCII
>)</dt>
<dd>Abort the "get an attribute" algorithm. The attribute's
name is the value of <var title="">attribute name</var> and its
value is the value of <var title="">attribute value</var>.</dd>
<dt>If it is in the range 0x41 (ASCII A) to 0x5A (ASCII
Z)</dt>
<dd>Append the Unicode character with code point <span title=""><var
title="">b</var>+0x20</span> to <var title="">attribute
value</var> (where <var title="">b</var> is the value of the
byte at <var title="">position</var>).</dd>
<dt>Anything else</dt>
<dd>Append the Unicode character with the same code point as the
value of the byte at <var title="">position</var>) to <var
title="">attribute value</var>.</dd>
</dl>
</li>
<li><p>Advance <var title="">position</var> to the next byte and
return to the previous step.</p></li>
</ol>
<p>For the sake of interoperability, user agents should not use a
pre-scan algorithm that returns different results than the one
described above. (But, if you do, please at least let us know, so
that we can improve this algorithm and benefit everyone...)</p>
</li>
<li><p>If the user agent has information on the likely encoding for
this page, e.g. based on the encoding of the page when it was last
visited, then return that encoding, with the <span
title="concept-encoding-confidence">confidence</span>
<i>tentative</i>, and abort these steps.</p></li>
<li>
<p>The user agent may attempt to autodetect the character encoding
from applying frequency analysis or other algorithms to the data
stream. Such algorithms may use information about the resource
other than the resource's contents, including the address of the
resource. If autodetection succeeds in determining a character
encoding, then return that encoding, with the <span
title="concept-encoding-confidence">confidence</span>
<i>tentative</i>, and abort these steps. <a
href="#refsUNIVCHARDET">[UNIVCHARDET]</a></p>
<p class="note">The UTF-8 encoding has a highly detectable bit
pattern. Documents that contain bytes with values greater than
0x7F which match the UTF-8 pattern are very likely to be UTF-8,
while documents with byte sequences that do not match it are very
likely not. User-agents are therefore encouraged to search for
this common encoding. <a href="#refsPPUTF8">[PPUTF8]</a> <a
href="#refsUTF8DET">[UTF8DET]</a></p>
</li>
<li>
<p>Otherwise, return an implementation-defined or user-specified
default character encoding, with the <span
title="concept-encoding-confidence">confidence</span>
<i>tentative</i>.</p>
<p>In controlled environments or in environments where the
encoding of documents can be prescribed (for example, for user
agents intended for dedicated use in new networks), the
comprehensive <code title="">UTF-8</code> encoding is
suggested.</p>
<p>In other environments, the default encoding is typically
dependent on the user's locale (an approximation of the languages,
and thus typically encodings, of the pages that the user is likely
to frequent). The following table gives suggested defaults based
on the user's locale, for compatibility with legacy
content. Locales are identified by BCP 47 language codes. <a
href="#refsBCP47">[BCP47]</a></p>
<!-- based on mozilla 1.9.1 localizations:
http://mxr.mozilla.org/l10n-mozilla1.9.1/find?string=global%2Fintl.properties&tree=l10n-mozilla1.9.1&hint= -->
<table>
<thead>
<tr>
<th>Locale language
<th>Suggested default encoding
<tbody>
<tr>
<td>ar
<td>UTF-8
<tr>
<td>be
<td>ISO-8859-5
<tr>
<td>bg
<td>windows-1251
<tr>
<td>cs<!-- -CZ -->
<td>ISO-8859-2
<tr>
<td>cy
<td>UTF-8
<tr>
<td>fa<!-- -IR -->
<td>UTF-8
<tr>
<td>he<!-- -IL -->
<td>windows-1255
<tr>
<td>hr
<td>UTF-8
<tr>
<td>hu<!-- -HU -->
<td>ISO-8859-2
<tr>
<td>ja <!-- and ja-JP-mac -->
<td>windows-31J <!-- Shift_JIS -->
<tr>
<td>kk
<td>UTF-8
<tr>
<td>ko<!-- -KR -->
<td>windows-949 <!-- EUC-KR -->
<tr>
<td>ku
<td>windows-1254 <!-- ISO-8859-9 -->
<tr>
<td>lt
<td>windows-1257
<tr>
<td>lv<!-- -LV -->
<td>ISO-8859-13
<tr>
<td>mk<!-- -MK -->
<td>UTF-8
<tr>
<td>or
<td>UTF-8
<tr>
<td>pl<!-- -PL -->
<td>ISO-8859-2
<tr>
<td>ro
<td>UTF-8
<tr>
<td>ru
<td>windows-1251
<tr>
<td>sk
<td>windows-1250
<tr>
<td>sl
<td>ISO-8859-2
<tr>
<td>sr
<td>UTF-8
<tr>
<td>th
<td>windows-874 <!-- TIS-620 -->
<tr>
<td>tr<!-- -TR -->
<td>windows-1254 <!-- ISO-8859-9 -->
<tr>
<td>uk
<td>windows-1251
<tr>
<td>vi
<td>UTF-8
<tr>
<td>zh-CN
<td>GB18030
<tr>
<td>zh-TW
<td>Big5
<tr>
<td>All other locales
<td>windows-1252
</table>
</li>
</ol>
<p>The <span>document's character encoding</span> must immediately
be set to the value returned from this algorithm, at the same time
as the user agent uses the returned value to select the decoder to
use for the input stream.</p>
<p class="note">This algorithm is a <span>willful violation</span>
of the HTTP specification, which requires that the encoding be
assumed to be ISO-8859-1 in the absence of a <span>character
encoding declaration</span> to the contrary, and of RFC 2046,
which requires that the encoding be assumed to be US-ASCII in the
absence of a <span>character encoding declaration</span> to the
contrary. This specification's third approach is motivated by a
desire to be maximally compatible with legacy content. <a
href="#refsHTTP">[HTTP]</a> <a href="#refsRFC2046">[RFC2046]</a></p>
<h5>Character encodings</h5>
<p>User agents must at a minimum support the UTF-8 and Windows-1252
encodings, but may support more.</p>
<p class="note">It is not unusual for Web browsers to support dozens
if not upwards of a hundred distinct character encodings.</p>
<p>User agents must support the <span>preferred MIME name</span> of
every character encoding they support, and should support all the
IANA-registered names and aliases of every character encoding they
support. <a href="#refsIANACHARSET">[IANACHARSET]</a></p>
<p>When comparing a string specifying a character encoding with the
name or alias of a character encoding to determine if they are
equal, user agents must remove any leading or trailing <span
title="space character">space characters</span> in both names, and
then perform the comparison in an <span>ASCII
case-insensitive</span> manner.</p>
<hr>
<p>When a user agent would otherwise use an encoding given in the
first column of the following table to either convert content to
Unicode characters or convert Unicode characters to bytes, it must
instead use the encoding given in the cell in the second column of
the same row. When a byte or sequence of bytes is treated
differently due to this encoding aliasing, it is said to have been
<dfn>misinterpreted for compatibility</dfn>.</p>
<table>
<caption>Character encoding overrides</caption>
<thead>
<tr> <th> Input encoding <th> Replacement encoding <th> References
<tbody>
<!-- how about EUC-JP? -->
<tr> <td> EUC-KR <td> windows-949 <td>
<a href="#refsEUCKR">[EUCKR]</a>
<a href="#refsWIN949">[WIN949]</a>
<tr> <td> GB2312 <td> GBK <td>
<a href="#refsRFC1345">[RFC1345]</a>
<a href="#refsGBK">[GBK]</a>
<tr> <td> GB_2312-80 <td> GBK <td>
<a href="#refsRFC1345">[RFC1345]</a>
<a href="#refsGBK">[GBK]</a>
<tr> <td> ISO-8859-1 <td> windows-1252 <td>
<a href="#refsRFC1345">[RFC1345]</a>
<a href="#refsWIN1252">[WIN1252]</a>
<tr> <td> ISO-8859-9 <td> windows-1254 <td>
<a href="#refsRFC1345">[RFC1345]</a>
<a href="#refsWIN1254">[WIN1254]</a>
<tr> <td> ISO-8859-11 <td> windows-874 <td>
<a href="#refsISO885911">[ISO885911]</a>
<a href="#refsWIN874">[WIN874]</a>
<tr> <td> KS_C_5601-1987 <td> windows-949 <td>
<a href="#refsRFC1345">[RFC1345]</a>
<a href="#refsWIN949">[WIN949]</a>
<tr> <td> Shift_JIS <td> windows-31J <td>
<a href="#refsSHIFTJIS">[SHIFTJIS]</a>
<a href="#refsWIN31J">[WIN31J]</a>
<tr> <td> TIS-620 <td> windows-874 <td>
<a href="#refsTIS620">[TIS620]</a>
<a href="#refsWIN874">[WIN874]</a>
<tr> <td> US-ASCII <td> windows-1252 <td>
<a href="#refsRFC1345">[RFC1345]</a>
<a href="#refsWIN1252">[WIN1252]</a>
</tbody>
</table>
<p class="note">The requirement to treat certain encodings as other
encodings according to the table above is a <span>willful
violation</span> of the W3C Character Model specification, motivated
by a desire for compatibility with legacy content. <a
href="#refsCHARMOD">[CHARMOD]</a></p>
<p>When a user agent is to use the UTF-16 encoding but no BOM has
been found, user agents must default to UTF-16LE.</p>
<p class="note">The requirement to default UTF-16 to LE rather than
BE is a <span>willful violation</span> of RFC 2781, motivated by a
desire for compatibility with legacy content. <a
href="#refsRFC2781">[RFC2781]</a></p>
<hr>
<p>User agents must not support the CESU-8, UTF-7, BOCU-1 and SCSU
encodings. <a href="#refsCESU8">[CESU8]</a> <a
href="#refsUTF7">[UTF7]</a> <a href="#refsBOCU1">[BOCU1]</a> <a
href="#refsSCSU">[SCSU]</a></p>
<p>Support for encodings based on EBCDIC is not recommended. This
encoding is rarely used for publicly-facing Web content.</p>
<p>Support for UTF-32 is not recommended. This encoding is rarely
used, and frequently implemented incorrectly.</p>
<p class="note">This specification does not make any attempt to
support EBCDIC-based encodings and UTF-32 in its algorithms; support
and use of these encodings can thus lead to unexpected behavior in
implementations of this specification.</p>
<h5>Preprocessing the input stream</h5>
<p>Given an encoding, the bytes in the input stream must be
converted to Unicode characters for the tokenizer, as described by
the rules for that encoding, except that the leading U+FEFF BYTE
ORDER MARK character, if any, must not be stripped by the encoding
layer (it is stripped by the rule below).</p> <!-- this is to
prevent two leading BOMs from being both stripped, once by the
decoder, and once by the parser -->
<p>Bytes or sequences of bytes in the original byte stream that
could not be converted to Unicode code points must be converted to
U+FFFD REPLACEMENT CHARACTERs.</p>
<p class="note">Bytes or sequences of bytes in the original byte
stream that did not conform to the encoding specification
(e.g. invalid UTF-8 byte sequences in a UTF-8 input stream) are
errors that conformance checkers are expected to report.</p>
<p>Any byte or sequence of bytes in the original byte stream that is
<span>misinterpreted for compatibility</span> is a <span>parse
error</span>.</p>
<p>One leading U+FEFF BYTE ORDER MARK character must be ignored if
any are present.</p>
<p class="note">The requirement to strip a U+FEFF BYTE ORDER MARK
character regardless of whether that character was used to determine
the byte order is a <span>willful violation</span> of Unicode,
motivated by a desire to increase the resilience of user agents in
the face of naïve transcoders.</p>
<p>All U+0000 NULL characters and code points in the range U+D800 to
U+DFFF<!-- surrogates not allowed e.g. in UTF-8, and we don't want
them to suddenly turn into codepoints when they go through a UTF-16
pipe --> in the input must be replaced by U+FFFD REPLACEMENT
CHARACTERs. Any occurrences of such characters and code points are
<span title="parse error">parse errors</span>.</p>
<p>Any occurrences of any characters in the ranges U+0001 to U+0008,
<!-- HT, LF allowed --> <!-- U+000B is in the next list --> <!-- FF,
CR allowed --> U+000E to U+001F, <!-- ASCII allowed --> U+007F
<!--to U+0084, (U+0085 NEL not allowed), U+0086--> to U+009F, U+FDD0
to U+FDEF, and characters U+000B, U+FFFE, U+FFFF, U+1FFFE, U+1FFFF,
U+2FFFE, U+2FFFF, U+3FFFE, U+3FFFF, U+4FFFE, U+4FFFF, U+5FFFE,
U+5FFFF, U+6FFFE, U+6FFFF, U+7FFFE, U+7FFFF, U+8FFFE, U+8FFFF,
U+9FFFE, U+9FFFF, U+AFFFE, U+AFFFF, U+BFFFE, U+BFFFF, U+CFFFE,
U+CFFFF, U+DFFFE, U+DFFFF, U+EFFFE, U+EFFFF, U+FFFFE, U+FFFFF,
U+10FFFE, and U+10FFFF are <span title="parse error">parse
errors</span>. These are all control characters or permanently
undefined Unicode characters (noncharacters).</p>
<p>U+000D CARRIAGE RETURN (CR) characters and U+000A LINE FEED (LF)
characters are treated specially. Any CR characters that are
followed by LF characters must be removed, and any CR characters not
followed by LF characters must be converted to LF characters. Thus,
newlines in HTML DOMs are represented by LF characters, and there
are never any CR characters in the input to the
<span>tokenization</span> stage.</p>
<p>The <dfn>next input character</dfn> is the first character in the
input stream that has not yet been <dfn>consumed</dfn>. Initially,
the <i>next input character</i> is the first character in the
input. The <dfn>current input character</dfn> is the last character
to have been <i>consumed</i>.</p>
<p>The <dfn>insertion point</dfn> is the position (just before a
character or just before the end of the input stream) where content
inserted using <code
title="dom-document-write">document.write()</code> is actually
inserted. The insertion point is relative to the position of the
character immediately after it, it is not an absolute offset into
the input stream. Initially, the insertion point is
undefined.</p>
<p>The "EOF" character in the tables below is a conceptual character
representing the end of the <span>input stream</span>. If the parser
is a <span>script-created parser</span>, then the end of the
<span>input stream</span> is reached when an <dfn>explicit "EOF"
character</dfn> (inserted by the <code
title="dom-document-close">document.close()</code> method) is
consumed. Otherwise, the "EOF" character is not a real character in
the stream, but rather the lack of any further characters.</p>
<h5>Changing the encoding while parsing</h5>
<p>When the parser requires the user agent to <dfn>change the
encoding</dfn>, it must run the following steps. This might happen
if the <span>encoding sniffing algorithm</span> described above
failed to find an encoding, or if it found an encoding that was not
the actual encoding of the file.</p>
<ol>
<li>If the new encoding is identical or equivalent to the encoding
that is already being used to interpret the input stream, then set
the <span title="concept-encoding-confidence">confidence</span> to
<i>certain</i> and abort these steps. This happens when the
encoding information found in the file matches what the
<span>encoding sniffing algorithm</span> determined to be the
encoding, and in the second pass through the parser if the first
pass found that the encoding sniffing algorithm described in the
earlier section failed to find the right encoding.</li>
<li>If the encoding that is already being used to interpret the
input stream is a UTF-16 encoding, then set the <span
title="concept-encoding-confidence">confidence</span> to
<i>certain</i> and abort these steps. The new encoding is ignored;
if it was anything but the same encoding, then it would be clearly
incorrect.</li>
<li>If the new encoding is a UTF-16 encoding, change it to
UTF-8.</li>
<li>If all the bytes up to the last byte converted by the current
decoder have the same Unicode interpretations in both the current
encoding and the new encoding, and if the user agent supports
changing the converter on the fly, then the user agent may change
to the new converter for the encoding on the fly. Set the
<span>document's character encoding</span> and the encoding used to
convert the input stream to the new encoding, set the <span
title="concept-encoding-confidence">confidence</span> to
<i>certain</i>, and abort these steps.</li>
<li>Otherwise, <span>navigate</span> to the document again, with
<span>replacement enabled</span>, and using the same <span>source
browsing context</span>, but this time skip the <span>encoding
sniffing algorithm</span> and instead just set the encoding to the
new encoding and the <span
title="concept-encoding-confidence">confidence</span> to
<i>certain</i>. Whenever possible, this should be done without
actually contacting the network layer (the bytes should be
re-parsed from memory), even if, e.g., the document is marked as
not being cacheable. If this is not possible and contacting the
network layer would involve repeating a request that uses a method
other than HTTP GET (<span title="concept-http-equivalent-get">or
equivalent</span> for non-HTTP URLs), then instead set the <span
title="concept-encoding-confidence">confidence</span> to
<i>certain</i> and ignore the new encoding. The resource will be
misinterpreted. User agents may notify the user of the situation,
to aid in application development.</li>
</ol>
</div>
<div class="impl">
<h4>Parse state</h4>
<h5>The insertion mode</h5>
<p>The <dfn>insertion mode</dfn> is a state variable that controls
the primary operation of the tree construction stage.</p>
<p>Initially, the <span>insertion mode</span> is "<span
title="insertion mode: initial">initial</span>". It can change to
"<span title="insertion mode: before html">before html</span>",
"<span title="insertion mode: before head">before head</span>",
"<span title="insertion mode: in head">in head</span>", "<span
title="insertion mode: in head noscript">in head noscript</span>",
"<span title="insertion mode: after head">after head</span>", "<span
title="insertion mode: in body">in body</span>", "<span
title="insertion mode: text">text</span>",
"<span title="insertion mode: in table">in table</span>", "<span
title="insertion mode: in table text">in table text</span>", "<span
title="insertion mode: in caption">in caption</span>", "<span
title="insertion mode: in column group">in column group</span>",
"<span title="insertion mode: in table body">in table body</span>",
"<span title="insertion mode: in row">in row</span>", "<span
title="insertion mode: in cell">in cell</span>", "<span
title="insertion mode: in select">in select</span>", "<span
title="insertion mode: in select in table">in select in
table</span>", "<span title="insertion mode: in foreign content">in
foreign content</span>", "<span title="insertion mode: after
body">after body</span>", "<span title="insertion mode: in
frameset">in frameset</span>", "<span title="insertion mode: after
frameset">after frameset</span>", "<span title="insertion mode:
after after body">after after body</span>", and "<span
title="insertion mode: after after frameset">after after
frameset</span>" during the course of the parsing, as described in
the <span>tree construction</span> stage. The insertion mode affects
how tokens are processed and whether CDATA sections are
supported.</p>
<p>Seven of these modes, namely "<span title="insertion mode: in
head">in head</span>", "<span title="insertion mode: in body">in
body</span>", "<span title="insertion mode: in table">in
table</span>", "<span title="insertion mode: in table body">in table
body</span>", "<span title="insertion mode: in row">in row</span>",
"<span title="insertion mode: in cell">in cell</span>", and "<span
title="insertion mode: in select">in select</span>", are special, in
that the other modes defer to them at various times. When the
algorithm below says that the user agent is to do something
"<dfn>using the rules for</dfn> the <var title="">m</var> insertion
mode", where <var title="">m</var> is one of these modes, the user
agent must use the rules described under the <var title="">m</var>
<span>insertion mode</span>'s section, but must leave the
<span>insertion mode</span> unchanged unless the rules in <var
title="">m</var> themselves switch the <span>insertion mode</span>
to a new value.</p>
<p>When the insertion mode is switched to "<span title="insertion
mode: text">text</span>" or "<span title="insertion mode: in table
text">in table text</span>", the <dfn>original insertion mode</dfn>
is also set. This is the insertion mode to which the tree
construction stage will return.</p>
<p>When the insertion mode is switched to "<span title="insertion
mode: in foreign content">in foreign content</span>", the
<dfn>secondary insertion mode</dfn> is also set. This secondary mode
is used within the rules for the "<span title="insertion mode: in
foreign content">in foreign content</span>" mode to handle HTML
(i.e. not foreign) content.</p>
<hr>
<p>When the steps below require the UA to <dfn>reset the insertion
mode appropriately</dfn>, it means the UA must follow these
steps:</p>
<ol>
<li>Let <var title="">last</var> be false.</li>
<li>Let <var title="">foreign</var> be false.</li>
<li>Let <var title="">node</var> be the last node in the
<span>stack of open elements</span>.</li>
<li><i>Loop</i>: If <var title="">node</var> is the first node in
the stack of open elements, then set <var title="">last</var> to
true and set <var title="">node</var> to the <var
title="">context</var> element. (<span>fragment case</span>)</li>
<li>If <var title="">node</var> is a <code>select</code> element,
then switch the <span>insertion mode</span> to "<span
title="insertion mode: in select">in select</span>" and jump to the
step marked <i title="">end</i>. (<span>fragment case</span>)</li>
<li>If <var title="">node</var> is a <code>td</code> or
<code>th</code> element and <var title="">last</var> is false, then
switch the <span>insertion mode</span> to "<span title="insertion
mode: in cell">in cell</span>" and jump to the step marked <i
title="">end</i>.</li>
<li>If <var title="">node</var> is a <code>tr</code> element, then
switch the <span>insertion mode</span> to "<span title="insertion
mode: in row">in row</span>" and jump to the step marked <i
title="">end</i>.</li>
<li>If <var title="">node</var> is a <code>tbody</code>,
<code>thead</code>, or <code>tfoot</code> element, then switch the
<span>insertion mode</span> to "<span title="insertion mode: in
table body">in table body</span>" and jump to the step marked <i
title="">end</i>.</li>
<li>If <var title="">node</var> is a <code>caption</code> element,
then switch the <span>insertion mode</span> to "<span
title="insertion mode: in caption">in caption</span>" and jump to
the step marked <i title="">end</i>.</li>
<li>If <var title="">node</var> is a <code>colgroup</code> element,
then switch the <span>insertion mode</span> to "<span
title="insertion mode: in column group">in column group</span>" and
jump to the step marked <i title="">end</i>. (<span>fragment
case</span>)</li>
<li>If <var title="">node</var> is a <code>table</code> element,
then switch the <span>insertion mode</span> to "<span
title="insertion mode: in table">in table</span>" and jump to the
step marked <i title="">end</i>.</li>
<li>If <var title="">node</var> is a <code>head</code> element,
then switch the <span>insertion mode</span> to "<span
title="insertion mode: in body">in body</span>" ("<span
title="insertion mode: in body">in body</span>"! <em> not "<span
title="insertion mode: in head">in head</span>"</em>!) and jump to
the step marked <i title="">end</i>. (<span>fragment
case</span>)</li> <!-- This is only here for now in case people
think that the spec accidentally omitted it and try to "fix"
it. Note that noscript-in-head is also handled this way. This is
all intentional. The only thing it doesn't handle is the
scripting-disabled fragment parsing case for a <head> element
containing a <noscript> which itself contains something other than
a <link> or a <style> element; you'd expect that to break out of
the <noscript> but it doesn't. This is an edge case that doesn't
affect the spec, since the algorithm for fragment parsing is only
used for innerHTML/outerHTML/insertAdjacentHTML(), where we know
scripting is enabled. -->
<li>If <var title="">node</var> is a <code>body</code> element,
then switch the <span>insertion mode</span> to "<span
title="insertion mode: in body">in body</span>" and jump to the
step marked <i title="">end</i>.</li>
<li>If <var title="">node</var> is a <code>frameset</code> element,
then switch the <span>insertion mode</span> to "<span
title="insertion mode: in frameset">in frameset</span>" and jump to
the step marked <i title="">end</i>. (<span>fragment
case</span>)</li>
<li>If <var title="">node</var> is an <code>html</code> element,
then <!--: if the <span><code title="">head</code> element
pointer</span> is null,--> switch the <span>insertion mode</span>
to "<span title="insertion mode: before head">before
head</span>"<!--, otherwise, switch the <span>insertion mode</span>
to "<span title="insertion mode: after head">after head</span>".-->
Then, <!-- in either case, --> jump to the step marked <i
title="">end</i>. (<span>fragment case</span>)</li> <!-- if the
head element pointer can ever be non-null when we're going through
these steps, we'll need to uncomment out the commented-out bits -->
<li>If <var title="">node</var> is an element from the <span>MathML
namespace</span> or the <span>SVG namespace</span>, then set the
<var title="">foreign</var> flag to true.</li>
<li>If <var title="">last</var> is true, then switch the
<span>insertion mode</span> to "<span title="insertion mode: in
body">in body</span>" and jump to the step marked <i
title="">end</i>. (<span>fragment case</span>)</li>
<li>Let <var title="">node</var> now be the node before <var
title="">node</var> in the <span>stack of open
elements</span>.</li>
<li>Return to the step marked <i>loop</i>.</li>
<li><i>End</i>: If <var title="">foreign</var> is true, switch the
<span>secondary insertion mode</span> to whatever the
<span>insertion mode</span> is set to, and switch the
<span>insertion mode</span> to "<span title="insertion mode: in
foreign content">in foreign content</span>".</li>
</ol>
<h5>The stack of open elements</h5>
<p>Initially, the <dfn>stack of open elements</dfn> is empty. The
stack grows downwards; the topmost node on the stack is the first
one added to the stack, and the bottommost node of the stack is the
most recently added node in the stack (notwithstanding when the
stack is manipulated in a random access fashion as part of <a
href="#adoptionAgency">the handling for misnested tags</a>).</p>
<p>The "<span title="insertion mode: before html">before
html</span>" <span>insertion mode</span> creates the
<code>html</code> root element node, which is then added to the
stack.</p>
<p>In the <span>fragment case</span>, the <span>stack of open
elements</span> is initialized to contain an <code>html</code>
element that is created as part of <span title="html fragment
parsing algorithm">that algorithm</span>. (The <span>fragment
case</span> skips the "<span title="insertion mode: before
html">before html</span>" <span>insertion mode</span>.)</p>
<p>The <code>html</code> node, however it is created, is the topmost
node of the stack. It never gets popped off the stack.</p>
<p>The <dfn>current node</dfn> is the bottommost node in this
stack.</p>
<p>The <dfn>current table</dfn> is the last <code>table</code>
element in the <span>stack of open elements</span>, if there is
one. If there is no <code>table</code> element in the <span>stack of
open elements</span> (<span>fragment case</span>), then the
<span>current table</span> is the first element in the <span>stack
of open elements</span> (the <code>html</code> element).</p>
<p>Elements in the stack fall into the following categories:</p>
<dl>
<dt><dfn>Special</dfn></dt>
<dd><p>The following HTML elements have varying levels of special
parsing rules: <code>address</code>, <code>area</code>,
<code>article</code>, <code>aside</code>, <code>base</code>,
<code>basefont</code>, <code>bgsound</code>,
<code>blockquote</code>, <code>body</code>, <code>br</code>,
<code>center</code>, <code>col</code>, <code>colgroup</code>,
<code>command</code>, <!--v2DDATAGRID--><code>datagrid</code>,
<code>dd</code>, <code>details</code>, <code>dir</code>,
<code>div</code>, <code>dl</code>, <code>dt</code>,
<code>embed</code>, <code>fieldset</code>, <code>figure</code>,
<code>footer</code>, <code>form</code>, <code>frame</code>,
<code>frameset</code>, <code>h1</code>, <code>h2</code>,
<code>h3</code>, <code>h4</code>, <code>h5</code>, <code>h6</code>,
<code>head</code>, <code>header</code>, <code>hgroup</code>,
<code>hr</code>, <code>iframe</code>, <!-- <code>image</code>,
(commented out because this isn't an element that can end up on the
stack, so it doesn't matter) --> <code>img</code>,
<code>input</code>, <code>isindex</code>, <code>li</code>,
<code>link</code>, <code>listing</code>, <code>menu</code>,
<code>meta</code>, <code>nav</code>, <code>noembed</code>,
<code>noframes</code>, <code>noscript</code>, <code>ol</code>,
<code>p</code>, <code>param</code>, <code>plaintext</code>,
<code>pre</code>, <code>script</code>, <code>section</code>,
<code>select</code>, <code>style</code>, <code>tbody</code>,
<code>textarea</code>, <code>tfoot</code>, <code>thead</code>,
<code>title</code>, <code>tr</code>, <code>ul</code>,
<code>wbr</code>, and <code>xmp</code>.</p></dd>
<dt><dfn>Scoping</dfn></dt>
<dd><p>The following HTML elements introduce new <span title="has
an element in scope">scopes</span> for various parts of the
parsing: <code>applet</code>, <code>button</code>,
<code>caption</code>, <code>html</code>, <code>marquee</code>,
<code>object</code>, <code>table</code>, <code>td</code>,
<code>th</code>, and SVG's <code>foreignObject</code>.</p></dd>
<dt><dfn>Formatting</dfn></dt>
<dd><p>The following HTML elements are those that end up in the
<span>list of active formatting elements</span>: <code>a</code>,
<code>b</code>, <code>big</code>, <code>code</code>,
<code>em</code>, <code>font</code>, <code>i</code>,
<code>nobr</code>, <code>s</code>, <code>small</code>,
<code>strike</code>, <code>strong</code>, <code>tt</code>, and
<code>u</code>.</p></dd>
<dt><dfn>Phrasing</dfn></dt>
<dd><p>All other elements found while parsing an HTML
document.</p></dd>
</dl>
<p>The <span>stack of open elements</span> is said to <dfn
title="has an element in the specific scope">have an element in a
specific scope</dfn> consisting of a list of element types <var
title="">list</var> when the following algorithm terminates in a
match state:</p>
<ol>
<li><p>Initialize <var title="">node</var> to be the <span>current
node</span> (the bottommost node of the stack).</p></li>
<li><p>If <var title="">node</var> is the target node, terminate in
a match state.</p></li>
<li><p>Otherwise, if <var title="">node</var> is one of the element
types in <var title="">list</var>, terminate in a failure
state.</p></li>
<li><p>Otherwise, set <var title="">node</var> to the previous
entry in the <span>stack of open elements</span> and return to step
2. (This will never fail, since the loop will always terminate in
the previous step if the top of the stack — an
<code>html</code> element — is reached.)</p></li>
</ol>
<p>The <span>stack of open elements</span> is said to <dfn
title="has an element in scope">have an element in scope</dfn> when
it <span>has an element in the specific scope</span> consisting
of the following element types:</p>
<ul class="brief">
<li><code>applet</code> in the HTML namespace</li>
<li><code>caption</code> in the HTML namespace</li>
<li><code>html</code> in the HTML namespace</li> <!-- (This can only happen if the <var title="">node</var> is the topmost node of the <span>stack of open elements</span>, and prevents the next step from being invoked if there are no more elements in the stack.) -->
<li><code>table</code> in the HTML namespace</li>
<li><code>td</code> in the HTML namespace</li>
<li><code>th</code> in the HTML namespace</li>
<li><code>button</code> in the HTML namespace</li>
<li><code>marquee</code> in the HTML namespace</li>
<li><code>object</code> in the HTML namespace</li>
<li><code title="">foreignObject</code> in the SVG namespace</li>
</ul>
<p>The <span>stack of open elements</span> is said to <dfn
title="has an element in list item scope">have an element in list
item scope</dfn> when it <span>has an element in the specific
scope</span> consisting of the following element types:</p>
<ul class="brief">
<li>All the element types listed above for the <i>has an element
in scope</i> algorithm.</li>
<li><code>ol</code> in the HTML namespace</li>
<li><code>ul</code> in the HTML namespace</li>
</ul>
<p>The <span>stack of open elements</span> is said to <dfn
title="has an element in table scope">have an element in <em>table
scope</em></dfn> when it <span>has an element in the specific
scope</span> consisting of the following element types:</p>
<ul class="brief">
<li><code>html</code> in the HTML namespace</li> <!-- (This can only happen if the <var title="">node</var> is the topmost node of the <span>stack of open elements</span>, and prevents the next step from being invoked if there are no more elements in the stack.) -->
<li><code>table</code> in the HTML namespace</li>
</ul>
<p>Nothing happens if at any time any of the elements in the
<span>stack of open elements</span> are moved to a new location in,
or removed from, the <code>Document</code> tree. In particular, the
stack is not changed in this situation. This can cause, amongst
other strange effects, content to be appended to nodes that are no
longer in the DOM.</p>
<p class="note">In some cases (namely, when <a
href="#adoptionAgency">closing misnested formatting elements</a>),
the stack is manipulated in a random-access fashion.</p>
<h5>The list of active formatting elements</h5>
<p>Initially, the <dfn>list of active formatting elements</dfn> is
empty. It is used to handle mis-nested <span
title="formatting">formatting element tags</span>.</p>
<p>The list contains elements in the <span>formatting</span>
category, and scope markers. The scope markers are inserted when
entering <code>applet</code> elements, buttons, <code>object</code>
elements, marquees, table cells, and table captions, and are used to
prevent formatting from "leaking" <em>into</em> <code>applet</code>
elements, buttons, <code>object</code> elements, marquees, and
tables.</p>
<p class="note">The scope markers are unrelated to the concept of an
element being <span title="has an element in scope">in
scope</span>.</p>
<p>In addition, each element in the <span>list of active formatting
elements</span> is associated with the token for which it was
created, so that further elements can be created for that token if
necessary.</p>
<p>When the steps below require the UA to <dfn>reconstruct the
active formatting elements</dfn>, the UA must perform the following
steps:</p>
<ol>
<li>If there are no entries in the <span>list of active formatting
elements</span>, then there is nothing to reconstruct; stop this
algorithm.</li>
<li>If the last (most recently added) entry in the <span>list of
active formatting elements</span> is a marker, or if it is an
element that is in the <span>stack of open elements</span>, then
there is nothing to reconstruct; stop this algorithm.</li>
<li>Let <var title="">entry</var> be the last (most recently added)
element in the <span>list of active formatting
elements</span>.</li>
<li>If there are no entries before <var title="">entry</var> in the
<span>list of active formatting elements</span>, then jump to step
8.</li>
<li>Let <var title="">entry</var> be the entry one earlier than
<var title="">entry</var> in the <span>list of active formatting
elements</span>.</li>
<li>If <var title="">entry</var> is neither a marker nor an element
that is also in the <span>stack of open elements</span>, go to step
4.</li>
<li>Let <var title="">entry</var> be the element one later than
<var title="">entry</var> in the <span>list of active formatting
elements</span>.</li>
<li><span>Create an element for the token</span> for which the
element <var title="">entry</var> was created, to obtain <var
title="">new element</var>.</li>
<li>Append <var title="">new element</var> to the <span>current
node</span> and push it onto the <span>stack of open
elements</span> so that it is the new <span>current
node</span>.</li>
<li>Replace the entry for <var title="">entry</var> in the list
with an entry for <var title="">new element</var>.</li>
<li>If the entry for <var title="">new element</var> in the
<span>list of active formatting elements</span> is not the last
entry in the list, return to step 7.</li>
</ol>
<p>This has the effect of reopening all the formatting elements that
were opened in the current body, cell, or caption (whichever is
youngest) that haven't been explicitly closed.</p>
<p class="note">The way this specification is written, the
<span>list of active formatting elements</span> always consists of
elements in chronological order with the least recently added
element first and the most recently added element last (except for
while steps 8 to 11 of the above algorithm are being executed, of
course).</p>
<p>When the steps below require the UA to <dfn>clear the list of
active formatting elements up to the last marker</dfn>, the UA must
perform the following steps:</p>
<ol>
<li>Let <var title="">entry</var> be the last (most recently added)
entry in the <span>list of active formatting elements</span>.</li>
<li>Remove <var title="">entry</var> from the <span>list of active
formatting elements</span>.</li>
<li>If <var title="">entry</var> was a marker, then stop the
algorithm at this point. The list has been cleared up to the last
marker.</li>
<li>Go to step 1.</li>
</ol>
<h5>The element pointers</h5>
<p>Initially, the <dfn><code title="">head</code> element
pointer</dfn> and the <dfn><code title="">form</code> element
pointer</dfn> are both null.</p>
<p>Once a <code>head</code> element has been parsed (whether
implicitly or explicitly) the <span><code title="">head</code>
element pointer</span> gets set to point to this node.</p>
<p>The <span><code title="">form</code> element pointer</span>
points to the last <code>form</code> element that was opened and
whose end tag has not yet been seen. It is used to make form
controls associate with forms in the face of dramatically bad
markup, for historical reasons.</p>
<h5>Other parsing state flags</h5>
<p>The <dfn>scripting flag</dfn> is set to "enabled" if <span
title="concept-n-script">scripting was enabled</span> for the
<code>Document</code> with which the parser is associated when the
parser was created, and "disabled" otherwise.</p>
<p class="note">The <span>scripting flag</span> can be enabled even
when the parser was originally created for the <span>HTML fragment
parsing algorithm</span>, even though <code>script</code> elements
don't execute in that case.</p>
<p>The <dfn>frameset-ok flag</dfn> is set to "ok" when the parser is
created. It is set to "not ok" after certain tokens are seen.</p>
</div>
<div class="impl">
<h4><dfn>Tokenization</dfn></h4>
<p>Implementations must act as if they used the following state
machine to tokenize HTML. The state machine must start in the
<span>data state</span>. Most states consume a single character,
which may have various side-effects, and either switches the state
machine to a new state to <em>reconsume</em> the same character, or
switches it to a new state (to consume the next character), or
repeats the same state (to consume the next character). Some states
have more complicated behavior and can consume several characters
before switching to another state. In some cases, the tokenizer
state is also changed by the tree construction stage.</p>
<p>The exact behavior of certain states depends on the
<span>insertion mode</span> and the <span>stack of open
elements</span>. Certain states also use a <dfn><var>temporary
buffer</var></dfn> to track progress.</p>
<p>The output of the tokenization step is a series of zero or more
of the following tokens: DOCTYPE, start tag, end tag, comment,
character, end-of-file. DOCTYPE tokens have a name, a public
identifier, a system identifier, and a <i>force-quirks
flag</i>. When a DOCTYPE token is created, its name, public
identifier, and system identifier must be marked as missing (which
is a distinct state from the empty string), and the <i>force-quirks
flag</i> must be set to <i>off</i> (its other state is
<i>on</i>). Start and end tag tokens have a tag name, a
<i>self-closing flag</i>, and a list of attributes, each of which
has a name and a value. When a start or end tag token is created,
its <i>self-closing flag</i> must be unset (its other state is that
it be set), and its attributes list must be empty. Comment and
character tokens have data.</p>
<p>When a token is emitted, it must immediately be handled by the
<span>tree construction</span> stage. The tree construction stage
can affect the state of the tokenization stage, and can insert
additional characters into the stream. (For example, the
<code>script</code> element can result in scripts executing and
using the <span>dynamic markup insertion</span> APIs to insert
characters into the stream being tokenized.)</p>
<p>When a start tag token is emitted with its <i>self-closing
flag</i> set, if the flag is not <dfn title="acknowledge
self-closing flag">acknowledged</dfn> when it is processed by the
tree construction stage, that is a <span>parse error</span>.</p>
<p>When an end tag token is emitted with attributes, that is a
<span>parse error</span>.</p>
<p>When an end tag token is emitted with its <i>self-closing
flag</i> set, that is a <span>parse error</span>.</p>
<p>An <dfn>appropriate end tag token</dfn> is an end tag token whose
tag name matches the tag name of the last start tag to have been
emitted from this tokenizer, if any. If no start tag has been
emitted from this tokenizer, then no end tag token is
appropriate.</p>
<p>Before each step of the tokenizer, the user agent must first
check the <span>parser pause flag</span>. If it is true, then the
tokenizer must abort the processing of any nested invocations of the
tokenizer, yielding control back to the caller.</p>
<p>The tokenizer state machine consists of the states defined in the
following subsections.</p>
<!-- Order of the lists below is supposed to be non-error then
error, by unicode, then EOF, ending with "anything else" -->
<h5><dfn>Data state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0026 AMPERSAND (&)</dt>
<dd>Switch to the <span>character reference in data
state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd>Switch to the <span>tag open state</span>.</dd>
<dt>EOF</dt>
<dd>Emit an end-of-file token.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Stay in the <span>data state</span>.</dd>
</dl>
<h5><dfn>Character reference in data state</dfn></h5>
<p>Attempt to <span>consume a character reference</span>, with no
<span>additional allowed character</span>.</p>
<p>If nothing is returned, emit a U+0026 AMPERSAND character
token.</p>
<p>Otherwise, emit the character token that was returned.</p>
<p>Finally, switch to the <span>data state</span>.</p>
<h5><dfn>RCDATA state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0026 AMPERSAND (&)</dt>
<dd>Switch to the <span>character reference in RCDATA
state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd>Switch to the <span>RCDATA less-than sign state</span>.</dd>
<dt>EOF</dt>
<dd>Emit an end-of-file token.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Stay in the <span>RCDATA state</span>.</dd>
</dl>
<h5><dfn>Character reference in RCDATA state</dfn></h5>
<p>Attempt to <span>consume a character reference</span>, with no
<span>additional allowed character</span>.</p>
<p>If nothing is returned, emit a U+0026 AMPERSAND character
token.</p>
<p>Otherwise, emit the character token that was returned.</p>
<p>Finally, switch to the <span>RCDATA state</span>.</p>
<h5><dfn>RAWTEXT state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd>Switch to the <span>RAWTEXT less-than sign state</span>.</dd>
<dt>EOF</dt>
<dd>Emit an end-of-file token.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Stay in the <span>RAWTEXT state</span>.</dd>
</dl>
<h5><dfn>Script data state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd>Switch to the <span>script data less-than sign state</span>.</dd>
<dt>EOF</dt>
<dd>Emit an end-of-file token.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Stay in the <span>script data state</span>.</dd>
</dl>
<h5><dfn>PLAINTEXT state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>EOF</dt>
<dd>Emit an end-of-file token.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Stay in the <span>PLAINTEXT state</span>.</dd>
</dl>
<h5><dfn>Tag open state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0021 EXCLAMATION MARK (!)</dt>
<dd>Switch to the <span>markup declaration open state</span>.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>Switch to the <span>close tag open state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Create a new start tag token, set its tag name to the
lowercase version of the <span>current input character</span> (add 0x0020 to the
character's code point), then switch to the <span>tag name
state</span>. (Don't emit the token yet; further details will
be filled in before it is emitted.)</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Create a new start tag token, set its tag name to the
<span>current input character</span>, then switch to the <span>tag
name state</span>. (Don't emit the token yet; further details will
be filled in before it is emitted.)</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Emit a U+003C LESS-THAN SIGN
character token and a U+003E GREATER-THAN SIGN character
token. Switch to the <span>data state</span>.</dd>
<dt>U+003F QUESTION MARK (?)</dt>
<dd><span>Parse error</span>. Switch to the <span>bogus
comment state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Emit a U+003C LESS-THAN SIGN
character token and reconsume the <span>current input
character</span> in the <span>data state</span>.</dd>
</dl>
<h5><dfn>Close tag open state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Create a new end tag token, set its tag name to the lowercase
version of the <span>current input character</span> (add 0x0020 to
the character's code point), then switch to the <span>tag name
state</span>. (Don't emit the token yet; further details will be
filled in before it is emitted.)</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Create a new end tag token, set its tag name to the
<span>current input character</span>, then switch to the <span>tag
name state</span>. (Don't emit the token yet; further details will
be filled in before it is emitted.)</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Switch to the <span>data
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Emit a U+003C LESS-THAN SIGN
character token and a U+002F SOLIDUS character token. Reconsume
the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Switch to the <span>bogus
comment state</span>.</dd>
</dl>
<h5><dfn>Tag name state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>before attribute name state</span>.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>Switch to the <span>self-closing start tag state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current tag token. Switch to the <span>data
state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
current tag token's tag name. Stay in the <span>tag name
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
tag token's tag name. Stay in the <span>tag name state</span>.</dd>
</dl>
<h5><dfn>RCDATA less-than sign state</dfn></h5>
<!-- identical to the RAWTEXT less-than sign state, except s/RAWTEXT/RCDATA/g -->
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002F SOLIDUS (/)</dt>
<dd>Set the <var>temporary buffer</var> to the empty string. Switch
to the <span>RCDATA end tag open state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token and reconsume the
<span>current input character</span> in the <span>RCDATA
state</span>.</dd>
</dl>
<h5><dfn>RCDATA end tag open state</dfn></h5>
<!-- identical to the RAWTEXT (and Script data) end tag open state, except s/RAWTEXT/RCDATA/g -->
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Create a new end tag token, and set its tag name to the
lowercase version of the <span>current input character</span> (add
0x0020 to the character's code point). Append the <span>current
input character</span> to the <var>temporary buffer</var>. Finally,
switch to the <span>RCDATA end tag name state</span>. (Don't emit
the token yet; further details will be filled in before it is
emitted.)</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Create a new end tag token, and set its tag name to the
<span>current input character</span>. Append the <span>current
input character</span> to the <var>temporary buffer</var>. Finally,
switch to the <span>RCDATA end tag name state</span>. (Don't emit
the token yet; further details will be filled in before it is
emitted.)</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
character token, and reconsume the <span>current input
character</span> in the <span>RCDATA state</span>.</dd>
</dl>
<h5><dfn>RCDATA end tag name state</dfn></h5>
<!-- identical to the RAWTEXT (and Script data) end tag name state, except s/RAWTEXT/RCDATA/g -->
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then switch to the <span>before attribute name
state</span>. Otherwise, treat it as per the "anything else" entry
below.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then switch to the <span>self-closing start tag
state</span>. Otherwise, treat it as per the "anything else" entry
below.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then emit the current tag token and switch to the
<span>data state</span>. Otherwise, treat it as per the "anything
else" entry below.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
current tag token's tag name. Append the <span>current input
character</span> to the <var>temporary buffer</var>. Stay in the
<span>RCDATA end tag name state</span>.</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Append the <span>current input character</span> to the current
tag token's tag name. Append the <span>current input
character</span> to the <var>temporary buffer</var>. Stay in the
<span>RCDATA end tag name state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
character token, a character token for each of the characters in
the <var>temporary buffer</var> (in the order they were added to
the buffer), and reconsume the <span>current input character</span>
in the <span>RCDATA state</span>.</dd>
</dl>
<h5><dfn>RAWTEXT less-than sign state</dfn></h5>
<!-- identical to the RCDATA less-than sign state, except s/RCDATA/RAWTEXT/g -->
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002F SOLIDUS (/)</dt>
<dd>Set the <var>temporary buffer</var> to the empty string. Switch
to the <span>RAWTEXT end tag open state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token and reconsume the
<span>current input character</span> in the <span>RAWTEXT
state</span>.</dd>
</dl>
<h5><dfn>RAWTEXT end tag open state</dfn></h5>
<!-- identical to the RCDATA (and Script data) end tag open state, except s/RCDATA/RAWTEXT/g -->
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Create a new end tag token, and set its tag name to the
lowercase version of the <span>current input character</span> (add
0x0020 to the character's code point). Append the <span>current
input character</span> to the <var>temporary buffer</var>. Finally,
switch to the <span>RAWTEXT end tag name state</span>. (Don't emit
the token yet; further details will be filled in before it is
emitted.)</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Create a new end tag token, and set its tag name to the
<span>current input character</span>. Append the <span>current
input character</span> to the <var>temporary buffer</var>. Finally,
switch to the <span>RAWTEXT end tag name state</span>. (Don't emit
the token yet; further details will be filled in before it is
emitted.)</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
character token, and reconsume the <span>current input
character</span> in the <span>RAWTEXT state</span>.</dd>
</dl>
<h5><dfn>RAWTEXT end tag name state</dfn></h5>
<!-- identical to the RCDATA (and Script data) end tag name state, except s/RCDATA/RAWTEXT/g -->
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then switch to the <span>before attribute name
state</span>. Otherwise, treat it as per the "anything else" entry
below.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then switch to the <span>self-closing start tag
state</span>. Otherwise, treat it as per the "anything else" entry
below.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then emit the current tag token and switch to the
<span>data state</span>. Otherwise, treat it as per the "anything
else" entry below.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
current tag token's tag name. Append the <span>current input
character</span> to the <var>temporary buffer</var>. Stay in the
<span>RAWTEXT end tag name state</span>.</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Append the <span>current input character</span> to the current
tag token's tag name. Append the <span>current input
character</span> to the <var>temporary buffer</var>. Stay in the
<span>RAWTEXT end tag name state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
character token, a character token for each of the characters in
the <var>temporary buffer</var> (in the order they were added to
the buffer), and reconsume the <span>current input character</span>
in the <span>RAWTEXT state</span>.</dd>
</dl>
<h5><dfn>Script data less-than sign state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002F SOLIDUS (/)</dt>
<dd>Set the <var>temporary buffer</var> to the empty string. Switch
to the <span>script data end tag open state</span>.</dd>
<dt>U+0021 EXCLAMATION MARK (!)</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token and a U+0021
EXCLAMATION MARK character token. Switch to the <span>script data
escape start state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token and reconsume the
<span>current input character</span> in the <span>script data
state</span>.</dd>
</dl>
<h5><dfn>Script data end tag open state</dfn></h5>
<!-- identical to the RCDATA (and RAWTEXT) end tag open state, except s/RCDATA/Script data/g -->
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Create a new end tag token, and set its tag name to the
lowercase version of the <span>current input character</span> (add
0x0020 to the character's code point). Append the <span>current
input character</span> to the <var>temporary buffer</var>. Finally,
switch to the <span>script data end tag name state</span>. (Don't emit
the token yet; further details will be filled in before it is
emitted.)</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Create a new end tag token, and set its tag name to the
<span>current input character</span>. Append the <span>current
input character</span> to the <var>temporary buffer</var>. Finally,
switch to the <span>script data end tag name state</span>. (Don't emit
the token yet; further details will be filled in before it is
emitted.)</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
character token, and reconsume the <span>current input
character</span> in the <span>script data state</span>.</dd>
</dl>
<h5><dfn>Script data end tag name state</dfn></h5>
<!-- identical to the RCDATA (and RAWTEXT) end tag name state, except s/RCDATA/Script data/g -->
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then switch to the <span>before attribute name
state</span>. Otherwise, treat it as per the "anything else" entry
below.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then switch to the <span>self-closing start tag
state</span>. Otherwise, treat it as per the "anything else" entry
below.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then emit the current tag token and switch to the
<span>data state</span>. Otherwise, treat it as per the "anything
else" entry below.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
current tag token's tag name. Append the <span>current input
character</span> to the <var>temporary buffer</var>. Stay in the
<span>script data end tag name state</span>.</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Append the <span>current input character</span> to the current
tag token's tag name. Append the <span>current input
character</span> to the <var>temporary buffer</var>. Stay in the
<span>script data end tag name state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
character token, a character token for each of the characters in
the <var>temporary buffer</var> (in the order they were added to
the buffer), and reconsume the <span>current input character</span>
in the <span>script data state</span>.</dd>
</dl>
<h5><dfn>Script data escape start state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Emit a U+002D HYPHEN-MINUS character token. Switch to the
<span>script data escape start dash state</span>.</dd>
<dt>Anything else</dt>
<dd>Reconsume the <span>current input character</span> in the
<span>script data state</span>.</dd>
</dl>
<h5><dfn>Script data escape start dash state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Emit a U+002D HYPHEN-MINUS character token. Switch to the
<span>script data escaped dash dash state</span>.</dd>
<dt>Anything else</dt>
<dd>Reconsume the <span>current input character</span> in the
<span>script data state</span>.</dd>
</dl>
<h5><dfn>Script data escaped state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Emit a U+002D HYPHEN-MINUS character token. Switch to the
<span>script data escaped dash state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd><p>Switch to the <span>script data escaped less-than sign
state</span>.</p></dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Stay in the <span>script data escaped state</span>.</dd>
</dl>
<h5><dfn>Script data escaped dash state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Emit a U+002D HYPHEN-MINUS character token. Switch to the
<span>script data escaped dash dash state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd><p>Switch to the <span>script data escaped less-than sign
state</span>.</p></dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Switch to the <span>script data escaped state</span>.</dd>
</dl>
<h5><dfn>Script data escaped dash dash state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Emit a U+002D HYPHEN-MINUS character token. Stay in the
<span>script data escaped dash dash state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd><p>Switch to the <span>script data escaped less-than sign
state</span>.</p></dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit a U+003E GREATER-THAN SIGN character token. Switch to the
<span>script data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Switch to the <span>script data escaped state</span>.</dd>
</dl>
<h5><dfn>Script data escaped less-than sign state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002F SOLIDUS (/)</dt>
<dd>Set the <var>temporary buffer</var> to the empty string. Switch
to the <span>script data escaped end tag open state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token and the
<span>current input character</span> as a character token. Set the
<var>temporary buffer</var> to the empty string. Append the
lowercase version of the <span>current input character</span> (add
0x0020 to the character's code point) to the <var>temporary
buffer</var>. Switch to the <span>script data double escape start
state</span>.</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token and the
<span>current input character</span> as a character token. Set the
<var>temporary buffer</var> to the empty string. Append the
<span>current input character</span> to the <var>temporary
buffer</var>. Switch to the <span>script data double escape start
state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token and reconsume the
<span>current input character</span> in the <span>script data
escaped state</span>.</dd>
</dl>
<h5><dfn>Script data escaped end tag open state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Create a new end tag token, and set its tag name to the
lowercase version of the <span>current input character</span> (add
0x0020 to the character's code point). Append the <span>current
input character</span> to the <var>temporary buffer</var>. Finally,
switch to the <span>script data escaped end tag name
state</span>. (Don't emit the token yet; further details will be
filled in before it is emitted.)</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Create a new end tag token, and set its tag name to the
<span>current input character</span>. Append the <span>current
input character</span> to the <var>temporary buffer</var>. Finally,
switch to the <span>script data escaped end tag name
state</span>. (Don't emit the token yet; further details will be
filled in before it is emitted.)</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
character token, and reconsume the <span>current input
character</span> in the <span>script data escaped state</span>.</dd>
</dl>
<h5><dfn>Script data escaped end tag name state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then switch to the <span>before attribute name
state</span>. Otherwise, treat it as per the "anything else" entry
below.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then switch to the <span>self-closing start tag
state</span>. Otherwise, treat it as per the "anything else" entry
below.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>If the current end tag token is an <span>appropriate end tag
token</span>, then emit the current tag token and switch to the
<span>data state</span>. Otherwise, treat it as per the "anything
else" entry below.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
current tag token's tag name. Append the <span>current input
character</span> to the <var>temporary buffer</var>. Stay in the
<span>script data escaped end tag name state</span>.</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Append the <span>current input character</span> to the current
tag token's tag name. Append the <span>current input
character</span> to the <var>temporary buffer</var>. Stay in the
<span>script data escaped end tag name state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit a U+003C LESS-THAN SIGN character token, a U+002F SOLIDUS
character token, a character token for each of the characters in
the <var>temporary buffer</var> (in the order they were added to
the buffer), and reconsume the <span>current input character</span>
in the <span>script data escaped state</span>.</dd>
</dl>
<h5><dfn>Script data double escape start state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dt>U+002F SOLIDUS (/)</dt>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the <span>current input character</span> as a character
token. If the <var>temporary buffer</var> is the string "<code
title="">script</code>", then switch to the <span>script data
double escaped state</span>. Otherwise, switch to the <span>script
data escaped state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Emit the <span>current input character</span> as a character
token. Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
<var>temporary buffer</var>. Stay in the <span>script data double
escape start state</span>.</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Emit the <span>current input character</span> as a character
token. Append the <span>current input character</span> to the
<var>temporary buffer</var>. Stay in the <span>script data double
escape start state</span>.</dd>
<dt>Anything else</dt>
<dd>Reconsume the <span>current input character</span> in the
<span>script data escaped state</span>.</dd>
</dl>
<h5><dfn>Script data double escaped state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Emit a U+002D HYPHEN-MINUS character token. Switch to the
<span>script data double escaped dash state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd><p>Emit a U+003C LESS-THAN SIGN character token. Switch to the
<span>script data double escaped less-than sign
state</span>.</p></dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Stay in the <span>script data double escaped
state</span>.</dd>
</dl>
<h5><dfn>Script data double escaped dash state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Emit a U+002D HYPHEN-MINUS character token. Switch to the
<span>script data double escaped dash dash state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd><p>Emit a U+003C LESS-THAN SIGN character token. Switch to the
<span>script data double escaped less-than sign
state</span>.</p></dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Switch to the <span>script data double escaped
state</span>.</dd>
</dl>
<h5><dfn>Script data double escaped dash dash state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Emit a U+002D HYPHEN-MINUS character token. Stay in the
<span>script data double escaped dash dash state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd><p>Emit a U+003C LESS-THAN SIGN character token. Switch to the
<span>script data double escaped less-than sign
state</span>.</p></dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit a U+003E GREATER-THAN SIGN character token. Switch to the
<span>script data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Emit the <span>current input character</span> as a character
token. Switch to the <span>script data double escaped
state</span>.</dd>
</dl>
<h5><dfn>Script data double escaped less-than sign state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002F SOLIDUS (/)</dt>
<dd>Emit a U+002F SOLIDUS character token. Set the <var>temporary
buffer</var> to the empty string. Switch to the <span>script data
double escape end state</span>.</dd>
<dt>Anything else</dt>
<dd>Reconsume the <span>current input character</span> in the
<span>script data double escaped state</span>.</dd>
</dl>
<h5><dfn>Script data double escape end state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dt>U+002F SOLIDUS (/)</dt>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the <span>current input character</span> as a character
token. If the <var>temporary buffer</var> is the string "<code
title="">script</code>", then switch to the <span>script data
escaped state</span>. Otherwise, switch to the <span>script data
double escaped state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Emit the <span>current input character</span> as a character
token. Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
<var>temporary buffer</var>. Stay in the <span>script data double
escape end state</span>.</dd>
<dt>U+0061 LATIN SMALL LETTER A through to U+007A LATIN SMALL LETTER Z</dt>
<dd>Emit the <span>current input character</span> as a character
token. Append the <span>current input character</span> to the
<var>temporary buffer</var>. Stay in the <span>script data double
escape end state</span>.</dd>
<dt>Anything else</dt>
<dd>Reconsume the <span>current input character</span> in the
<span>script data double escaped state</span>.</dd>
</dl>
<h5><dfn>Before attribute name state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>before attribute name state</span>.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>Switch to the <span>self-closing start tag state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current tag token. Switch to the <span>data
state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Start a new attribute in the current tag token. Set that
attribute's name to the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point), and its
value to the empty string. Switch to the <span>attribute name
state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dt>U+0027 APOSTROPHE (')</dt>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dt>U+003D EQUALS SIGN (=)</dt>
<dd><span>Parse error</span>. Treat it as per the "anything else"
entry below.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Start a new attribute in the current tag token. Set that
attribute's name to the <span>current input character</span>, and its value to
the empty string. Switch to the <span>attribute name
state</span>.</dd>
</dl>
<h5><dfn>Attribute name state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>after attribute name state</span>.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>Switch to the <span>self-closing start tag state</span>.</dd>
<dt>U+003D EQUALS SIGN (=)</dt>
<dd>Switch to the <span>before attribute value state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current tag token. Switch to the <span>data
state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
current attribute's name. Stay in the <span>attribute name
state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dt>U+0027 APOSTROPHE (')</dt>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd><span>Parse error</span>. Treat it as per the "anything else"
entry below.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
attribute's name. Stay in the <span>attribute name
state</span>.</dd>
</dl>
<p>When the user agent leaves the attribute name state (and before
emitting the tag token, if appropriate), the complete attribute's
name must be compared to the other attributes on the same token;
if there is already an attribute on the token with the exact same
name, then this is a <span>parse error</span> and the new
attribute must be dropped, along with the value that gets
associated with it (if any).</p>
<h5><dfn>After attribute name state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>after attribute name state</span>.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>Switch to the <span>self-closing start tag state</span>.</dd>
<dt>U+003D EQUALS SIGN (=)</dt>
<dd>Switch to the <span>before attribute value state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current tag token. Switch to the <span>data
state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Start a new attribute in the current tag token. Set that
attribute's name to the lowercase version of the <span>current
input character</span> (add 0x0020 to the character's code point),
and its value to the empty string. Switch to the <span>attribute
name state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dt>U+0027 APOSTROPHE (')</dt>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dd><span>Parse error</span>. Treat it as per the "anything else"
entry below.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Start a new attribute in the current tag token. Set that
attribute's name to the <span>current input character</span>, and
its value to the empty string. Switch to the <span>attribute name
state</span>.</dd>
</dl>
<h5><dfn>Before attribute value state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>before attribute value state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dd>Switch to the <span>attribute value (double-quoted) state</span>.</dd>
<dt>U+0026 AMPERSAND (&)</dt>
<dd>Switch to the <span>attribute value (unquoted) state</span>
and reconsume this <span>current input character</span>.</dd>
<dt>U+0027 APOSTROPHE (')</dt>
<dd>Switch to the <span>attribute value (single-quoted) state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Emit the current tag token. Switch to
the <span>data state</span>.</dd>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dt>U+003D EQUALS SIGN (=)</dt>
<dt>U+0060 GRAVE ACCENT (`)</dt>
<dd><span>Parse error</span>. Treat it as per the "anything else"
entry below.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
attribute's value. Switch to the <span>attribute value (unquoted)
state</span>.</dd>
</dl>
<h5><dfn>Attribute value (double-quoted) state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0022 QUOTATION MARK (")</dt>
<dd>Switch to the <span>after attribute value (quoted)
state</span>.</dd>
<dt>U+0026 AMPERSAND (&)</dt>
<dd>Switch to the <span>character reference in attribute value
state</span>, with the <span>additional allowed character</span>
being U+0022 QUOTATION MARK (").</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
attribute's value. Stay in the <span>attribute value
(double-quoted) state</span>.</dd>
</dl>
<h5><dfn>Attribute value (single-quoted) state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0027 APOSTROPHE (')</dt>
<dd>Switch to the <span>after attribute value (quoted)
state</span>.</dd>
<dt>U+0026 AMPERSAND (&)</dt>
<dd>Switch to the <span>character reference in attribute value
state</span>, with the <span>additional allowed character</span>
being U+0027 APOSTROPHE (').</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
attribute's value. Stay in the <span>attribute value
(single-quoted) state</span>.</dd>
</dl>
<h5><dfn>Attribute value (unquoted) state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>before attribute name state</span>.</dd>
<dt>U+0026 AMPERSAND (&)</dt>
<dd>Switch to the <span>character reference in attribute value
state</span>, with the <span>additional allowed character</span>
being U+003E GREATER-THAN SIGN (>).</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current tag token. Switch to the <span>data
state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dt>U+0027 APOSTROPHE (')</dt>
<dt>U+003C LESS-THAN SIGN (<)</dt>
<dt>U+003D EQUALS SIGN (=)</dt>
<dt>U+0060 GRAVE ACCENT (`)</dt>
<dd><span>Parse error</span>. Treat it as per the "anything else"
entry below.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
attribute's value. Stay in the <span>attribute value (unquoted)
state</span>.</dd>
</dl>
<h5><dfn>Character reference in attribute value state</dfn></h5>
<p>Attempt to <span>consume a character reference</span>.</p>
<p>If nothing is returned, append a U+0026 AMPERSAND character to
the current attribute's value.</p>
<p>Otherwise, append the returned character token to the current
attribute's value.</p>
<p>Finally, switch back to the attribute value state that you were
in when were switched into this state.</p>
<h5><dfn>After attribute value (quoted) state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>before attribute name state</span>.</dd>
<dt>U+002F SOLIDUS (/)</dt>
<dd>Switch to the <span>self-closing start tag state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current tag token. Switch to the <span>data
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Reconsume the character in
the <span>before attribute name state</span>.</dd>
</dl>
<h5><dfn>Self-closing start tag state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Set the <i>self-closing flag</i> of the current tag
token. Emit the current tag token. Switch to the <span>data
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Reconsume the character in
the <span>before attribute name state</span>.</dd>
</dl>
<h5><dfn>Bogus comment state</dfn></h5>
<p>Consume every character up to and including the first U+003E
GREATER-THAN SIGN character (>) or the end of the file (EOF),
whichever comes first. Emit a comment token whose data is the
concatenation of all the characters starting from and including
the character that caused the state machine to switch into the
bogus comment state, up to and including the character immediately
before the last consumed character (i.e. up to the character just
before the U+003E or EOF character). (If the comment was started
by the end of the file (EOF), the token is empty.)</p>
<p>Switch to the <span>data state</span>.</p>
<p>If the end of the file was reached, reconsume the EOF
character.</p>
<h5><dfn>Markup declaration open state</dfn></h5>
<p>If the next two characters are both U+002D HYPHEN-MINUS
characters (-), consume those two characters, create a comment token
whose data is the empty string, and switch to the <span>comment
start state</span>.</p>
<p>Otherwise, if the next seven characters are an <span>ASCII
case-insensitive</span> match for the word "DOCTYPE", then consume
those characters and switch to the <span>DOCTYPE state</span>.</p>
<p>Otherwise, if the <span>insertion mode</span> is "<span
title="insertion mode: in foreign content">in foreign
content</span>" and the <span>current node</span> is not an element
in the <span>HTML namespace</span> and the next seven characters are
an <span>case-sensitive</span> match for the string "[CDATA[" (the
five uppercase letters "CDATA" with a U+005B LEFT SQUARE BRACKET
character before and after), then consume those characters and
switch to the <span>CDATA section state</span>.</p>
<p>Otherwise, this is a <span>parse error</span>. Switch to the
<span>bogus comment state</span>. The next character that is
consumed, if any, is the first character that will be in the
comment.</p>
<h5><dfn>Comment start state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Switch to the <span>comment start dash state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Emit the comment token. Switch to the
<span>data state</span>.</dd> <!-- see comment in comment end state
-->
<dt>EOF</dt>
<dd><span>Parse error</span>. Emit the comment token. Reconsume
the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the comment
token's data. Switch to the <span>comment state</span>.</dd>
</dl>
<h5><dfn>Comment start dash state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Switch to the <span>comment end state</span></dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Emit the comment token. Switch to
the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Emit the comment token. Reconsume the
EOF character in the <span>data state</span>.</dd> <!-- see comment
in comment end state -->
<dt>Anything else</dt>
<dd>Append a U+002D HYPHEN-MINUS character (-) and the
<span>current input character</span> to the comment token's
data. Switch to the <span>comment state</span>.</dd>
</dl>
<h5><dfn id="comment">Comment state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Switch to the <span>comment end dash state</span></dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Emit the comment token. Reconsume the
EOF character in the <span>data state</span>.</dd> <!-- see comment
in comment end state -->
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the comment
token's data. Stay in the <span>comment state</span>.</dd>
</dl>
<h5><dfn>Comment end dash state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Switch to the <span>comment end state</span></dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Emit the comment token. Reconsume the
EOF character in the <span>data state</span>.</dd> <!-- see comment
in comment end state -->
<dt>Anything else</dt>
<dd>Append a U+002D HYPHEN-MINUS character (-) and the
<span>current input character</span> to the comment token's
data. Switch to the <span>comment state</span>.</dd>
</dl>
<h5><dfn>Comment end state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the comment token. Switch to the <span>data
state</span>.</dd>
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd><span>Parse error</span>. Append two U+002D HYPHEN-MINUS
characters (-) and the <span>current input character</span> to the
comment token's data. Switch to the <span>comment end space
state</span>.</dd>
<dt>U+0021 EXCLAMATION MARK (!)</dt>
<dd><span>Parse error</span>. Switch to the <span>comment end bang
state</span>.</dd>
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd><span>Parse error</span>. Append a U+002D HYPHEN-MINUS
character (-) to the comment token's data. Stay in the
<span>comment end state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Emit the comment token. Reconsume
the EOF character in the <span>data state</span>.</dd> <!-- For
security reasons: otherwise, hostile user could put a <script> in
a comment e.g. in a blog comment and then DOS the server so that
the end tag isn't read, and then the commented <script> tag would
be treated as live code -->
<dt>Anything else</dt>
<dd><span>Parse error</span>. Append two U+002D HYPHEN-MINUS
characters (-) and the <span>current input character</span> to the
comment token's data. Switch to the <span>comment
state</span>.</dd>
</dl>
<h5><dfn>Comment end bang state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Append two U+002D HYPHEN-MINUS characters (-) and a U+0021
EXCLAMATION MARK character (!) to the comment token's data. Switch
to the <span>comment end dash state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the comment token. Switch to the <span>data
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Emit the comment token. Reconsume
the EOF character in the <span>data state</span>.</dd> <!-- see
comment in comment end state -->
<dt>Anything else</dt>
<dd>Append two U+002D HYPHEN-MINUS characters (-), a U+0021
EXCLAMATION MARK character (!), and the <span>current input
character</span> to the comment token's data. Switch to the
<span>comment state</span>.</dd>
</dl>
<h5><dfn>Comment end space state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Append the <span>current input character</span> to the comment token's data. Stay in
the <span>comment end space state</span>.</dd>
<dt>U+002D HYPHEN-MINUS (-)</dt>
<dd>Switch to the <span>comment end dash state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the comment token. Switch to the <span>data
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Emit the comment token. Reconsume
the EOF character in the <span>data state</span>.</dd> <!-- see
comment in comment end state -->
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the comment token's data. Switch
to the <span>comment state</span>.</dd>
</dl>
<h5><dfn>DOCTYPE state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>before DOCTYPE name state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Create a new DOCTYPE token. Set its
<i>force-quirks flag</i> to <i>on</i>. Emit the token. Reconsume
the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Reconsume the character in the
<span>before DOCTYPE name state</span>.</dd>
</dl>
<h5><dfn>Before DOCTYPE name state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>before DOCTYPE name state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Create a new DOCTYPE token. Set the token's name to the
lowercase version of the <span>current input character</span> (add 0x0020 to the
character's code point). Switch to the <span>DOCTYPE name
state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Create a new DOCTYPE token. Set its
<i>force-quirks flag</i> to <i>on</i>. Emit the token. Switch to
the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Create a new DOCTYPE token. Set its
<i>force-quirks flag</i> to <i>on</i>. Emit the token. Reconsume
the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Create a new DOCTYPE token. Set the token's name to the
<span>current input character</span>. Switch to the <span>DOCTYPE name
state</span>.</dd>
</dl>
<h5><dfn>DOCTYPE name state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>after DOCTYPE name state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current DOCTYPE token. Switch to the <span>data
state</span>.</dd>
<dt>U+0041 LATIN CAPITAL LETTER A through to U+005A LATIN CAPITAL LETTER Z</dt>
<dd>Append the lowercase version of the <span>current input
character</span> (add 0x0020 to the character's code point) to the
current DOCTYPE token's name. Stay in the <span>DOCTYPE name
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
DOCTYPE token's name. Stay in the <span>DOCTYPE name
state</span>.</dd>
</dl>
<h5><dfn>After DOCTYPE name state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>after DOCTYPE name state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current DOCTYPE token. Switch to the <span>data
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>
<p>If the six characters starting from the <span>current input
character</span> are an <span>ASCII case-insensitive</span> match
for the word "PUBLIC", then consume those characters and switch to
the <span>after DOCTYPE public keyword state</span>.</p>
<p>Otherwise, if the six characters starting from the
<span>current input character</span> are an <span>ASCII
case-insensitive</span> match for the word "SYSTEM", then consume
those characters and switch to the <span>after DOCTYPE system
keyword state</span>.</p>
<p>Otherwise, this is the <span>parse error</span>. Set the
DOCTYPE token's <i>force-quirks flag</i> to <i>on</i>. Switch to
the <span>bogus DOCTYPE state</span>.</p>
</dd>
</dl>
<h5><dfn>After DOCTYPE public keyword state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>before DOCTYPE public identifier
state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's public
identifier to the empty string (not missing), then switch to the
<span>DOCTYPE public identifier (double-quoted) state</span>.</dd>
<dt>U+0027 APOSTROPHE (')</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's public
identifier to the empty string (not missing), then switch to the
<span>DOCTYPE public identifier (single-quoted) state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE
token. Switch to the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Switch to the <span>bogus
DOCTYPE state</span>.</dd>
</dl>
<h5><dfn>Before DOCTYPE public identifier state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>before DOCTYPE public identifier state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dd>Set the DOCTYPE token's public identifier to the empty string
(not missing), then switch to the <span>DOCTYPE public identifier
(double-quoted) state</span>.</dd>
<dt>U+0027 APOSTROPHE (')</dt>
<dd>Set the DOCTYPE token's public identifier to the empty string
(not missing), then switch to the <span>DOCTYPE public identifier
(single-quoted) state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE
token. Switch to the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Switch to the <span>bogus
DOCTYPE state</span>.</dd>
</dl>
<h5><dfn>DOCTYPE public identifier (double-quoted) state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0022 QUOTATION MARK (")</dt>
<dd>Switch to the <span>after DOCTYPE public identifier state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE
token. Switch to the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current DOCTYPE
token's public identifier. Stay in the <span>DOCTYPE public
identifier (double-quoted) state</span>.</dd>
</dl>
<h5><dfn>DOCTYPE public identifier (single-quoted) state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0027 APOSTROPHE (')</dt>
<dd>Switch to the <span>after DOCTYPE public identifier state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE
token. Switch to the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current DOCTYPE
token's public identifier. Stay in the <span>DOCTYPE public
identifier (single-quoted) state</span>.</dd>
</dl>
<h5><dfn>After DOCTYPE public identifier state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>between DOCTYPE public and system
identifiers state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current DOCTYPE token. Switch to the <span>data
state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's system
identifier to the empty string (not missing), then switch to the
<span>DOCTYPE system identifier (double-quoted) state</span>.</dd>
<dt>U+0027 APOSTROPHE (')</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's system
identifier to the empty string (not missing), then switch to the
<span>DOCTYPE system identifier (single-quoted) state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Switch to the <span>bogus
DOCTYPE state</span>.</dd>
</dl>
<h5><dfn>Between DOCTYPE public and system identifiers state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>between DOCTYPE public and system identifiers
state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current DOCTYPE token. Switch to the <span>data
state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dd>Set the DOCTYPE token's system identifier to the empty string
(not missing), then switch to the <span>DOCTYPE system identifier
(double-quoted) state</span>.</dd>
<dt>U+0027 APOSTROPHE (')</dt>
<dd>Set the DOCTYPE token's system identifier to the empty string
(not missing), then switch to the <span>DOCTYPE system identifier
(single-quoted) state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Switch to the <span>bogus
DOCTYPE state</span>.</dd>
</dl>
<h5><dfn>After DOCTYPE system keyword state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Switch to the <span>before DOCTYPE system identifier
state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's system
identifier to the empty string (not missing), then switch to the
<span>DOCTYPE system identifier (double-quoted) state</span>.</dd>
<dt>U+0027 APOSTROPHE (')</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's system
identifier to the empty string (not missing), then switch to the
<span>DOCTYPE system identifier (single-quoted) state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE
token. Switch to the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Switch to the <span>bogus
DOCTYPE state</span>.</dd>
</dl>
<h5><dfn>Before DOCTYPE system identifier state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>before DOCTYPE system identifier state</span>.</dd>
<dt>U+0022 QUOTATION MARK (")</dt>
<dd>Set the DOCTYPE token's system identifier to the empty string
(not missing), then switch to the <span>DOCTYPE system identifier
(double-quoted) state</span>.</dd>
<dt>U+0027 APOSTROPHE (')</dt>
<dd>Set the DOCTYPE token's system identifier to the empty string
(not missing), then switch to the <span>DOCTYPE system identifier
(single-quoted) state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE
token. Switch to the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Switch to the <span>bogus
DOCTYPE state</span>.</dd>
</dl>
<h5><dfn>DOCTYPE system identifier (double-quoted) state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0022 QUOTATION MARK (")</dt>
<dd>Switch to the <span>after DOCTYPE system identifier
state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE
token. Switch to the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
DOCTYPE token's system identifier. Stay in the <span>DOCTYPE system
identifier (double-quoted) state</span>.</dd>
</dl>
<h5><dfn>DOCTYPE system identifier (single-quoted) state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0027 APOSTROPHE (')</dt>
<dd>Switch to the <span>after DOCTYPE system identifier
state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE
token. Switch to the <span>data state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Append the <span>current input character</span> to the current
DOCTYPE token's system identifier. Stay in the <span>DOCTYPE system
identifier (single-quoted) state</span>.</dd>
</dl>
<h5><dfn>After DOCTYPE system identifier state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dd>Stay in the <span>after DOCTYPE system identifier
state</span>.</dd>
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the current DOCTYPE token. Switch to the <span>data
state</span>.</dd>
<dt>EOF</dt>
<dd><span>Parse error</span>. Set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>. Emit that DOCTYPE token.
Reconsume the EOF character in the <span>data state</span>.</dd>
<dt>Anything else</dt>
<dd><span>Parse error</span>. Switch to the <span>bogus DOCTYPE
state</span>. (This does <em>not</em> set the DOCTYPE token's
<i>force-quirks flag</i> to <i>on</i>.)</dd>
</dl>
<h5><dfn>Bogus DOCTYPE state</dfn></h5>
<p>Consume the <span>next input character</span>:</p>
<dl class="switch">
<dt>U+003E GREATER-THAN SIGN (>)</dt>
<dd>Emit the DOCTYPE token. Switch to the <span>data
state</span>.</dd>
<dt>EOF</dt>
<dd>Emit the DOCTYPE token. Reconsume the EOF character in the
<span>data state</span>.</dd>
<dt>Anything else</dt>
<dd>Stay in the <span>bogus DOCTYPE state</span>.</dd>
</dl>
<h5><dfn>CDATA section state</dfn></h5>
<p>Consume every character up to the next occurrence of the three
character sequence U+005D RIGHT SQUARE BRACKET U+005D RIGHT SQUARE
BRACKET U+003E GREATER-THAN SIGN (<code title="">]]></code>), or the
end of the file (EOF), whichever comes first. Emit a series of
character tokens consisting of all the characters consumed except
the matching three character sequence at the end (if one was found
before the end of the file).</p>
<p>Switch to the <span>data state</span>.</p>
<p>If the end of the file was reached, reconsume the EOF
character.</p>
<h5>Tokenizing character references</h5>
<p>This section defines how to <dfn>consume a character
reference</dfn>. This definition is used when parsing character
references <span title="character reference in data state">in
text</span> and <span title="character reference in attribute value
state">in attributes</span>.</p>
<p>The behavior depends on the identity of the next character (the
one immediately after the U+0026 AMPERSAND character):</p>
<dl class="switch">
<dt>U+0009 CHARACTER TABULATION</dt>
<dt>U+000A LINE FEED (LF)</dt>
<dt>U+000C FORM FEED (FF)</dt>
<!--<dt>U+000D CARRIAGE RETURN (CR)</dt>-->
<dt>U+0020 SPACE</dt>
<dt>U+003C LESS-THAN SIGN</dt>
<dt>U+0026 AMPERSAND</dt>
<dt>EOF</dt>
<dt>The <dfn>additional allowed character</dfn>, if there is one</dt>
<dd>Not a character reference. No characters are consumed, and
nothing is returned. (This is not an error, either.)</dd>
<dt>U+0023 NUMBER SIGN (#)</dt>
<dd>
<p>Consume the U+0023 NUMBER SIGN.</p>
<p>The behavior further depends on the character after the U+0023
NUMBER SIGN:</p>
<dl class="switch">
<dt>U+0078 LATIN SMALL LETTER X</dt>
<dt>U+0058 LATIN CAPITAL LETTER X</dt>
<dd>
<p>Consume the X.</p>
<p>Follow the steps below, but using the range of characters
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061 LATIN
SMALL LETTER A to U+0066 LATIN SMALL LETTER F, and U+0041 LATIN
CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F (in other
words, 0-9, A-F, a-f).</p>
<p>When it comes to interpreting the number, interpret it as a
hexadecimal number.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Follow the steps below, but using the range of characters
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).</p>
<p>When it comes to interpreting the number, interpret it as a
decimal number.</p>
</dd>
</dl>
<p>Consume as many characters as match the range of characters
given above.</p>
<p>If no characters match the range, then don't consume any
characters (and unconsume the U+0023 NUMBER SIGN character and, if
appropriate, the X character). This is a <span>parse
error</span>; nothing is returned.</p>
<p>Otherwise, if the next character is a U+003B SEMICOLON, consume
that too. If it isn't, there is a <span>parse
error</span>.</p>
<p>If one or more characters match the range, then take them all
and interpret the string of characters as a number (either
hexadecimal or decimal as appropriate).</p>
<p>If that number is one of the numbers in the first column of the
following table, then this is a <span>parse error</span>. Find the
row with that number in the first column, and return a character
token for the Unicode character given in the second column of that
row.</p>
<table>
<thead>
<tr><th>Number <th colspan=2>Unicode character
<tbody>
<tr><td>0x00 <td>U+FFFD <td>REPLACEMENT CHARACTER
<tr><td>0x0D <td>U+000A <td>LINE FEED (LF)
<tr><td>0x80 <td>U+20AC <td>EURO SIGN (€)
<tr><td>0x81 <td>U+0081 <td><control>
<tr><td>0x82 <td>U+201A <td>SINGLE LOW-9 QUOTATION MARK (‚)
<tr><td>0x83 <td>U+0192 <td>LATIN SMALL LETTER F WITH HOOK (ƒ)
<tr><td>0x84 <td>U+201E <td>DOUBLE LOW-9 QUOTATION MARK („)
<tr><td>0x85 <td>U+2026 <td>HORIZONTAL ELLIPSIS (…)
<tr><td>0x86 <td>U+2020 <td>DAGGER (†)
<tr><td>0x87 <td>U+2021 <td>DOUBLE DAGGER (‡)
<tr><td>0x88 <td>U+02C6 <td>MODIFIER LETTER CIRCUMFLEX ACCENT (ˆ)
<tr><td>0x89 <td>U+2030 <td>PER MILLE SIGN (‰)
<tr><td>0x8A <td>U+0160 <td>LATIN CAPITAL LETTER S WITH CARON (Š)
<tr><td>0x8B <td>U+2039 <td>SINGLE LEFT-POINTING ANGLE QUOTATION MARK (‹)
<tr><td>0x8C <td>U+0152 <td>LATIN CAPITAL LIGATURE OE (Œ)
<tr><td>0x8D <td>U+008D <td><control>
<tr><td>0x8E <td>U+017D <td>LATIN CAPITAL LETTER Z WITH CARON (Ž)
<tr><td>0x8F <td>U+008F <td><control>
<tr><td>0x90 <td>U+0090 <td><control>
<tr><td>0x91 <td>U+2018 <td>LEFT SINGLE QUOTATION MARK (‘)
<tr><td>0x92 <td>U+2019 <td>RIGHT SINGLE QUOTATION MARK (’)
<tr><td>0x93 <td>U+201C <td>LEFT DOUBLE QUOTATION MARK (“)
<tr><td>0x94 <td>U+201D <td>RIGHT DOUBLE QUOTATION MARK (”)
<tr><td>0x95 <td>U+2022 <td>BULLET (•)
<tr><td>0x96 <td>U+2013 <td>EN DASH (–)
<tr><td>0x97 <td>U+2014 <td>EM DASH (—)
<tr><td>0x98 <td>U+02DC <td>SMALL TILDE (˜)
<tr><td>0x99 <td>U+2122 <td>TRADE MARK SIGN (™)
<tr><td>0x9A <td>U+0161 <td>LATIN SMALL LETTER S WITH CARON (š)
<tr><td>0x9B <td>U+203A <td>SINGLE RIGHT-POINTING ANGLE QUOTATION MARK (›)
<tr><td>0x9C <td>U+0153 <td>LATIN SMALL LIGATURE OE (œ)
<tr><td>0x9D <td>U+009D <td><control>
<tr><td>0x9E <td>U+017E <td>LATIN SMALL LETTER Z WITH CARON (ž)
<tr><td>0x9F <td>U+0178 <td>LATIN CAPITAL LETTER Y WITH DIAERESIS (Ÿ)
</table>
<p>Otherwise, if the number is in the range 0xD800 to 0xDFFF<!--
surrogates not allowed; see the comment in the "preprocessing the
input stream" section for details --> or is greater than 0x10FFFF,
then this is a <span>parse error</span>. Return a U+FFFD
REPLACEMENT CHARACTER.</p>
<p>Otherwise, return a character token for the Unicode character
whose code point is that number.
<!-- this is the same as the equivalent list in the input stream
section -->
If the number is in the range 0x0001 to 0x0008, <!-- HT, LF
allowed --> <!-- U+000B is in the next list --> <!-- FF, CR
allowed --> 0x000E to 0x001F, <!-- ASCII allowed --> 0x007F <!--to
0x0084, (0x0085 NEL not allowed), 0x0086--> to 0x009F, 0xFDD0 to
0xFDEF, or is one of 0x000B, 0xFFFE, 0xFFFF, 0x1FFFE, 0x1FFFF,
0x2FFFE, 0x2FFFF, 0x3FFFE, 0x3FFFF, 0x4FFFE, 0x4FFFF, 0x5FFFE,
0x5FFFF, 0x6FFFE, 0x6FFFF, 0x7FFFE, 0x7FFFF, 0x8FFFE, 0x8FFFF,
0x9FFFE, 0x9FFFF, 0xAFFFE, 0xAFFFF, 0xBFFFE, 0xBFFFF, 0xCFFFE,
0xCFFFF, 0xDFFFE, 0xDFFFF, 0xEFFFE, 0xEFFFF, 0xFFFFE, 0xFFFFF,
0x10FFFE, or 0x10FFFF, then this is a <span>parse
error</span>.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Consume the maximum number of characters possible, with the
consumed characters matching one of the identifiers in the first
column of the <span>named character references</span> table (in a
<span>case-sensitive</span> manner).</p>
<p>If no match can be made, then this is a <span>parse
error</span>. No characters are consumed, and nothing is
returned.</p>
<p>If the last character matched is not a U+003B SEMICOLON
character (;), there is a <span>parse error</span>.</p>
<p>If the character reference is being consumed <span
title="character reference in attribute value state">as part of an
attribute</span>, and the last character matched is not a U+003B
SEMICOLON character (;), and the next character is in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN
CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, or U+0061 LATIN
SMALL LETTER A to U+007A LATIN SMALL LETTER Z, then, for
historical reasons, all the characters that were matched after the
U+0026 AMPERSAND character (&) must be unconsumed, and nothing
is returned.</p>
<p>Otherwise, return a character token for the character
corresponding to the character reference name (as given by the
second column of the <span>named character references</span>
table).</p>
<div class="example">
<p>If the markup contains <code title="">I'm &notit; I tell
you</code>, the character reference is parsed as "not", as in,
<code title="">I'm ¬it; I tell you</code>. But if the markup
was <code title="">I'm &notin; I tell you</code>, the
character reference would be parsed as "notin;", resulting in
<code title="">I'm ∉ I tell you</code>.</p>
</div>
</dd>
</dl>
</div>
<div class="impl">
<!-- v2: One thing that this doesn't define is handling deeply
nested documents. There are compatibility requirements around that:
you can't throw away the elements altogether, consider Tux made only
with opening <font> elements, one per character. Seems that the best
thing to do is to close some formatting elements from the middle of
the stack when you hit a limit, or something. -->
<h4><dfn>Tree construction</dfn></h4>
<p>The input to the tree construction stage is a sequence of tokens
from the <span>tokenization</span> stage. The tree construction
stage is associated with a DOM <code>Document</code> object when a
parser is created. The "output" of this stage consists of
dynamically modifying or extending that document's DOM tree.</p>
<p>This specification does not define when an interactive user agent
has to render the <code>Document</code> so that it is available to
the user, or when it has to begin accepting user input.</p>
<p>As each token is emitted from the tokenizer, the user agent must
process the token according to the rules given in the section
corresponding to the current <span>insertion mode</span>.</p>
<p>When the steps below require the UA to <dfn>insert a
character</dfn> into a node, if that node has a child immediately
before where the character is to be inserted, and that child is a
<code>Text</code> node, and that <code>Text</code> node was the last
node that the parser inserted into the document, then the character
must be appended to that <code>Text</code> node; otherwise, a new
<code>Text</code> node whose data is just that character must be
inserted in the appropriate place.</p>
<div class="example">
<p>Here are some sample inputs to the parser and the corresponding
number of text nodes that they result in, assuming a user agent
that executes scripts.</p>
<table>
<thead>
<tr>
<th>Input <th>Number of text nodes
<tbody>
<tr>
<td><pre>A<script>
var script = document.getElementsByTagName('script')[0];
document.body.removeChild(script);
</script>B</pre>
<td>Two adjacent text nodes in the document, containing "A" and "B".
<tr>
<td><pre>A<script>
var text = document.createTextNode('B');
document.body.appendChild(text);
</script>C</pre>
<td>Four text nodes; "A" before the script, the script's contents, "B" after the script, and then, immediately after that, "C".
<tr>
<td><pre>A<script>
var text = document.getElementsByTagName('script')[0].firstChild;
text.data = 'B';
document.body.appendChild(text);
</script>B</pre>
<td>Two adjacent text nodes in the document, containing "A" and "BB".
<tr>
<td><pre>A<table>B<tr>C</tr>C</table></pre>
<td>Three adjacent text nodes before the table, containing "A", "B", and "CC" respectively. (This is caused by <span title="foster parent">foster parenting</span>.)
<tr>
<td><pre>A<table><tr> B</tr> B</table></pre>
<td>Two adjacent text nodes before the table, containing "A" and " B B" (space-B-space-B) respectively. (This is caused by <span title="foster parent">foster parenting</span>.)
<tr>
<td><pre>A<table><tr> B</tr> </em>C</table></pre>
<td>Three adjacent text nodes before the table, containing "A", " B" (space-B), and "C" respectively, and one text node inside the table (as a child of a <code>tbody</code>) with a single space character. (Space characters separated from non-space characters by non-character tokens are not affected by <span title="foster parent">foster parenting</span>, even if those other tokens then get ignored.)
</table>
</div>
<p id="mutation-during-parsing">DOM mutation events must not fire
for changes caused by the UA parsing the document. (Conceptually,
the parser is not mutating the DOM, it is constructing it.) This
includes the parsing of any content inserted using <code
title="dom-document-write">document.write()</code> and <code
title="dom-document-writeln">document.writeln()</code> calls. <a
href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p class="note">Not all of the tag names mentioned below are
conformant tag names in this specification; many are included to
handle legacy content. They still form part of the algorithm that
implementations are required to implement to claim conformance.</p>
<p class="note">The algorithm described below places no limit on the
depth of the DOM tree generated, or on the length of tag names,
attribute names, attribute values, text nodes, etc. While
implementors are encouraged to avoid arbitrary limits, it is
recognized that <a href="#hardwareLimitations">practical
concerns</a> will likely force user agents to impose nesting depth
constraints.</p>
<h5>Creating and inserting elements</h5>
<p>When the steps below require the UA to <dfn title="create an
element for the token">create an element for a token</dfn> in a
particular namespace, the UA must create a node implementing the
interface appropriate for the element type corresponding to the tag
name of the token in the given namespace (as given in the
specification that defines that element, e.g. for an <code>a</code>
element in the <span>HTML namespace</span>, this specification
defines it to be the <code>HTMLAnchorElement</code> interface), with
the tag name being the name of that element, with the node being in
the given namespace, and with the attributes on the node being those
given in the given token.</p>
<p>The interface appropriate for an element in the <span>HTML
namespace</span> that is not defined in this specification (or
<span>other applicable specifications</span>) is
<code>HTMLUnknownElement</code>. Element in other namespaces whose
interface is not defined by that namespace's specification must use
the interface <code>Element</code>.</p>
<p>When a <span title="category-reset">resettable</span> element is
created in this manner, its <span
title="concept-form-reset-control">reset algorithm</span> must be
invoked once the attributes are set. (This initializes the element's
<span title="concept-fe-value">value</span> and <span
title="concept-fe-checked">checkedness</span> based on the element's
attributes.)</p>
<hr>
<p>When the steps below require the UA to <dfn>insert an HTML
element</dfn> for a token, the UA must first <span>create an element
for the token</span> in the <span>HTML namespace</span>, and then
append this node to the <span>current node</span>, and push it onto
the <span>stack of open elements</span> so that it is the new
<span>current node</span>.</p>
<p>The steps below may also require that the UA insert an HTML
element in a particular place, in which case the UA must follow the
same steps except that it must insert or append the new node in the
location specified instead of appending it to the <span>current
node</span>. (This happens in particular during the parsing of
tables with invalid content.)</p>
<p>If an element created by the <span>insert an HTML element</span>
algorithm is a <span>form-associated element</span>, and the
<span><code title="">form</code> element pointer</span> is not null,
and the newly created element doesn't have a <code
title="attr-fae-form">form</code> attribute, the user agent must
<span title="concept-form-association">associate</span> the newly
created element with the <code>form</code> element pointed to by the
<span><code title="">form</code> element pointer</span> before
inserting it wherever it is to be inserted.</p>
<hr>
<p>When the steps below require the UA to <dfn>insert a foreign
element</dfn> for a token, the UA must first <span>create an element
for the token</span> in the given namespace, and then append this
node to the <span>current node</span>, and push it onto the
<span>stack of open elements</span> so that it is the new
<span>current node</span>. If the newly created element has an <code
title="">xmlns</code> attribute in the <span>XMLNS namespace</span>
whose value is not exactly the same as the element's namespace, that
is a <span>parse error</span>. Similarly, if the newly created
element has an <code title="">xmlns:xlink</code> attribute in the
<span>XMLNS namespace</span> whose value is not the <span>XLink
Namespace</span>, that is a <span>parse error</span>.</p>
<p>When the steps below require the user agent to <dfn>adjust MathML
attributes</dfn> for a token, then, if the token has an attribute
named <code title="">definitionurl</code>, change its name to <code
title="">definitionURL</code> (note the case difference).</p>
<p>When the steps below require the user agent to <dfn>adjust SVG
attributes</dfn> for a token, then, for each attribute on the token
whose attribute name is one of the ones in the first column of the
following table, change the attribute's name to the name given in
the corresponding cell in the second column. (This fixes the case of
SVG attributes that are not all lowercase.)</p>
<table>
<thead>
<tr> <th> Attribute name on token <th> Attribute name on element
<tbody>
<tr> <td> <code title="">attributename</code> <td> <code title="">attributeName</code>
<tr> <td> <code title="">attributetype</code> <td> <code title="">attributeType</code>
<tr> <td> <code title="">basefrequency</code> <td> <code title="">baseFrequency</code>
<tr> <td> <code title="">baseprofile</code> <td> <code title="">baseProfile</code>
<tr> <td> <code title="">calcmode</code> <td> <code title="">calcMode</code>
<tr> <td> <code title="">clippathunits</code> <td> <code title="">clipPathUnits</code>
<tr> <td> <code title="">contentscripttype</code> <td> <code title="">contentScriptType</code>
<tr> <td> <code title="">contentstyletype</code> <td> <code title="">contentStyleType</code>
<tr> <td> <code title="">diffuseconstant</code> <td> <code title="">diffuseConstant</code>
<tr> <td> <code title="">edgemode</code> <td> <code title="">edgeMode</code>
<tr> <td> <code title="">externalresourcesrequired</code> <td> <code title="">externalResourcesRequired</code>
<tr> <td> <code title="">filterres</code> <td> <code title="">filterRes</code>
<tr> <td> <code title="">filterunits</code> <td> <code title="">filterUnits</code>
<tr> <td> <code title="">glyphref</code> <td> <code title="">glyphRef</code>
<tr> <td> <code title="">gradienttransform</code> <td> <code title="">gradientTransform</code>
<tr> <td> <code title="">gradientunits</code> <td> <code title="">gradientUnits</code>
<tr> <td> <code title="">kernelmatrix</code> <td> <code title="">kernelMatrix</code>
<tr> <td> <code title="">kernelunitlength</code> <td> <code title="">kernelUnitLength</code>
<tr> <td> <code title="">keypoints</code> <td> <code title="">keyPoints</code>
<tr> <td> <code title="">keysplines</code> <td> <code title="">keySplines</code>
<tr> <td> <code title="">keytimes</code> <td> <code title="">keyTimes</code>
<tr> <td> <code title="">lengthadjust</code> <td> <code title="">lengthAdjust</code>
<tr> <td> <code title="">limitingconeangle</code> <td> <code title="">limitingConeAngle</code>
<tr> <td> <code title="">markerheight</code> <td> <code title="">markerHeight</code>
<tr> <td> <code title="">markerunits</code> <td> <code title="">markerUnits</code>
<tr> <td> <code title="">markerwidth</code> <td> <code title="">markerWidth</code>
<tr> <td> <code title="">maskcontentunits</code> <td> <code title="">maskContentUnits</code>
<tr> <td> <code title="">maskunits</code> <td> <code title="">maskUnits</code>
<tr> <td> <code title="">numoctaves</code> <td> <code title="">numOctaves</code>
<tr> <td> <code title="">pathlength</code> <td> <code title="">pathLength</code>
<tr> <td> <code title="">patterncontentunits</code> <td> <code title="">patternContentUnits</code>
<tr> <td> <code title="">patterntransform</code> <td> <code title="">patternTransform</code>
<tr> <td> <code title="">patternunits</code> <td> <code title="">patternUnits</code>
<tr> <td> <code title="">pointsatx</code> <td> <code title="">pointsAtX</code>
<tr> <td> <code title="">pointsaty</code> <td> <code title="">pointsAtY</code>
<tr> <td> <code title="">pointsatz</code> <td> <code title="">pointsAtZ</code>
<tr> <td> <code title="">preservealpha</code> <td> <code title="">preserveAlpha</code>
<tr> <td> <code title="">preserveaspectratio</code> <td> <code title="">preserveAspectRatio</code>
<tr> <td> <code title="">primitiveunits</code> <td> <code title="">primitiveUnits</code>
<tr> <td> <code title="">refx</code> <td> <code title="">refX</code>
<tr> <td> <code title="">refy</code> <td> <code title="">refY</code>
<tr> <td> <code title="">repeatcount</code> <td> <code title="">repeatCount</code>
<tr> <td> <code title="">repeatdur</code> <td> <code title="">repeatDur</code>
<tr> <td> <code title="">requiredextensions</code> <td> <code title="">requiredExtensions</code>
<tr> <td> <code title="">requiredfeatures</code> <td> <code title="">requiredFeatures</code>
<tr> <td> <code title="">specularconstant</code> <td> <code title="">specularConstant</code>
<tr> <td> <code title="">specularexponent</code> <td> <code title="">specularExponent</code>
<tr> <td> <code title="">spreadmethod</code> <td> <code title="">spreadMethod</code>
<tr> <td> <code title="">startoffset</code> <td> <code title="">startOffset</code>
<tr> <td> <code title="">stddeviation</code> <td> <code title="">stdDeviation</code>
<tr> <td> <code title="">stitchtiles</code> <td> <code title="">stitchTiles</code>
<tr> <td> <code title="">surfacescale</code> <td> <code title="">surfaceScale</code>
<tr> <td> <code title="">systemlanguage</code> <td> <code title="">systemLanguage</code>
<tr> <td> <code title="">tablevalues</code> <td> <code title="">tableValues</code>
<tr> <td> <code title="">targetx</code> <td> <code title="">targetX</code>
<tr> <td> <code title="">targety</code> <td> <code title="">targetY</code>
<tr> <td> <code title="">textlength</code> <td> <code title="">textLength</code>
<tr> <td> <code title="">viewbox</code> <td> <code title="">viewBox</code>
<tr> <td> <code title="">viewtarget</code> <td> <code title="">viewTarget</code>
<tr> <td> <code title="">xchannelselector</code> <td> <code title="">xChannelSelector</code>
<tr> <td> <code title="">ychannelselector</code> <td> <code title="">yChannelSelector</code>
<tr> <td> <code title="">zoomandpan</code> <td> <code title="">zoomAndPan</code>
</table>
<p>When the steps below require the user agent to <dfn>adjust
foreign attributes</dfn> for a token, then, if any of the attributes
on the token match the strings given in the first column of the
following table, let the attribute be a namespaced attribute, with
the prefix being the string given in the corresponding cell in the
second column, the local name being the string given in the
corresponding cell in the third column, and the namespace being the
namespace given in the corresponding cell in the fourth
column. (This fixes the use of namespaced attributes, in particular
<span title="attr-xml-lang"><code title="">lang</code> attributes in
the <span>XML namespace</span></span>.)</p>
<table>
<thead>
<tr> <th> Attribute name <th> Prefix <th> Local name <th> Namespace
<tbody>
<tr> <td> <code title="">xlink:actuate</code> <td> <code title="">xlink</code> <td> <code title="">actuate</code> <td> <span>XLink namespace</span>
<tr> <td> <code title="">xlink:arcrole</code> <td> <code title="">xlink</code> <td> <code title="">arcrole</code> <td> <span>XLink namespace</span>
<tr> <td> <code title="">xlink:href</code> <td> <code title="">xlink</code> <td> <code title="">href</code> <td> <span>XLink namespace</span>
<tr> <td> <code title="">xlink:role</code> <td> <code title="">xlink</code> <td> <code title="">role</code> <td> <span>XLink namespace</span>
<tr> <td> <code title="">xlink:show</code> <td> <code title="">xlink</code> <td> <code title="">show</code> <td> <span>XLink namespace</span>
<tr> <td> <code title="">xlink:title</code> <td> <code title="">xlink</code> <td> <code title="">title</code> <td> <span>XLink namespace</span>
<tr> <td> <code title="">xlink:type</code> <td> <code title="">xlink</code> <td> <code title="">type</code> <td> <span>XLink namespace</span>
<tr> <td> <code title="">xml:base</code> <td> <code title="">xml</code> <td> <code title="">base</code> <td> <span>XML namespace</span> <!-- attr-xml-base -->
<tr> <td> <code title="">xml:lang</code> <td> <code title="">xml</code> <td> <code title="">lang</code> <td> <span>XML namespace</span>
<tr> <td> <code title="">xml:space</code> <td> <code title="">xml</code> <td> <code title="">space</code> <td> <span>XML namespace</span>
<tr> <td> <code title="">xmlns</code> <td> (none) <td> <code title="">xmlns</code> <td> <span>XMLNS namespace</span>
<tr> <td> <code title="">xmlns:xlink</code> <td> <code title="">xmlns</code> <td> <code title="">xlink</code> <td> <span>XMLNS namespace</span>
</table>
<hr>
<p>The <dfn>generic raw text element parsing algorithm</dfn> and the
<dfn>generic RCDATA element parsing algorithm</dfn> consist of the
following steps. These algorithms are always invoked in response to
a start tag token.</p>
<ol>
<li><p><span>Insert an HTML element</span> for the token.</p></li>
<li><p>If the algorithm that was invoked is the <span>generic raw
text element parsing algorithm</span>, switch the tokenizer to the
<span>RAWTEXT state</span>; otherwise the algorithm invoked
was the <span>generic RCDATA element parsing algorithm</span>,
switch the tokenizer to the <span>RCDATA state</span>.</p></li>
<li><p>Let the <span>original insertion mode</span> be the current
<span>insertion mode</span>.</p>
<li><p>Then, switch the <span>insertion mode</span> to "<span
title="insertion mode: text">text</span>".</p></li>
</ol>
<h5>Closing elements that have implied end tags</h5>
<p>When the steps below require the UA to <dfn>generate implied end
tags</dfn>, then, while the <span>current node</span> is a
<code>dd</code> element, a <code>dt</code> element, an
<code>li</code> element, an <code>option</code> element, an
<code>optgroup</code> element, a <code>p</code> element, an
<code>rp</code> element, or an <code>rt</code> element, the UA must
pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p>If a step requires the UA to generate implied end tags but lists
an element to exclude from the process, then the UA must perform the
above steps as if that element was not in the above list.</p>
<h5>Foster parenting</h5>
<p>Foster parenting happens when content is misnested in tables.</p>
<p>When a node <var title="">node</var> is to be <dfn title="foster
parent">foster parented</dfn>, the node <var title="">node</var>
must be inserted into the <i>foster parent element</i>.</p>
<p>The <dfn>foster parent element</dfn> is the parent element of the
last <code>table</code> element in the <span>stack of open
elements</span>, if there is a <code>table</code> element and it has
such a parent element. If there is no <code>table</code> element in
the <span>stack of open elements</span> (<span>fragment
case</span>), then the <i>foster parent element</i> is the first
element in the <span>stack of open elements</span> (the
<code>html</code> element). Otherwise, if there is a
<code>table</code> element in the <span>stack of open
elements</span>, but the last <code>table</code> element in the
<span>stack of open elements</span> has no parent, or its parent
node is not an element, then the <i>foster parent element</i> is
the element before the last <code>table</code> element in the
<span>stack of open elements</span>.</p>
<p>If the <i>foster parent element</i> is the parent element of the
last <code>table</code> element in the <span>stack of open
elements</span>, then <var title="">node</var> must be inserted
immediately <em>before</em> the last <code>table</code> element in
the <span>stack of open elements</span> in the <i>foster parent
element</i>; otherwise, <var title="">node</var> must be
<em>appended</em> to the <i>foster parent element</i>.</p>
<h5>The "<dfn title="insertion mode: initial">initial</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: initial">initial</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p>Ignore the token.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <code>Document</code>
object with the <code title="">data</code> attribute set to the
data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p>If the DOCTYPE token's name is not a
<span>case-sensitive</span> match for the string "<code
title="">html</code>", or the token's public identifier is not
missing, or the token's system identifier is neither missing nor a
<span>case-sensitive</span> match for the string
"<code>about:legacy-compat</code>", and none of the sets of
conditions in the following list are matched, then there is a
<span>parse error</span>. If one of the sets of conditions in the
following list is matched, then there is an <dfn>obsolete
permitted DOCTYPE</dfn>.</p>
<ul>
<!-- only things that trigger no-quirks mode and were valid in
some other spec are allowed in this list -->
<li>The DOCTYPE token's name is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">html</code>", the token's public identifier is the
<span>case-sensitive</span> string "<code
title="">-//W3C//DTD HTML 4.0//EN</code>", and the
token's system identifier is either missing or the
<span>case-sensitive</span> string "<code
title="">http://www.w3.org/TR/REC-html40/strict.dtd</code>".</li>
<li>The DOCTYPE token's name is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">html</code>", the token's public identifier is the
<span>case-sensitive</span> string "<code
title="">-//W3C//DTD HTML 4.01//EN</code>", and the
token's system identifier is either missing or the
<span>case-sensitive</span> string "<code
title="">http://www.w3.org/TR/html4/strict.dtd</code>".</li>
<li>The DOCTYPE token's name is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">html</code>", the token's public identifier is the
<span>case-sensitive</span> string "<code
title="">-//W3C//DTD XHTML 1.0 Strict//EN</code>",
and the token's system identifier is the
<span>case-sensitive</span> string "<code
title="">http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd</code>".</li>
<li>The DOCTYPE token's name is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">html</code>", the token's public identifier is the
<span>case-sensitive</span> string "<code
title="">-//W3C//DTD XHTML 1.1//EN</code>", and the
token's system identifier is the <span>case-sensitive</span>
string "<code
title="">http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd</code>".</li>
</ul>
<p>Conformance checkers may, based on the values (including
presence or lack thereof) of the DOCTYPE token's name, public
identifier, or system identifier, switch to a conformance checking
mode for another language (e.g. based on the DOCTYPE token a
conformance checker could recognize that the document is an
HTML4-era document, and defer to an HTML4 conformance
checker.)</p>
<p>Append a <code>DocumentType</code> node to the
<code>Document</code> node, with the <code title="">name</code>
attribute set to the name given in the DOCTYPE token, or the empty
string if the name was missing; the <code title="">publicId</code>
attribute set to the public identifier given in the DOCTYPE token,
or the empty string if the public identifier was missing; the
<code title="">systemId</code> attribute set to the system
identifier given in the DOCTYPE token, or the empty string if the
system identifier was missing; and the other attributes specific
to <code>DocumentType</code> objects set to null and empty lists
as appropriate. Associate the <code>DocumentType</code> node with
the <code>Document</code> object so that it is returned as the
value of the <code title="">doctype</code> attribute of the
<code>Document</code> object.</p>
<p id="quirks-mode-doctypes">Then, if the DOCTYPE token matches
one of the conditions in the following list, then set the
<code>Document</code> to <span>quirks mode</span>:</p>
<ul class="brief">
<li> The <i>force-quirks flag</i> is set to <i>on</i>. </li>
<li> The name is set to anything other than "<code title="">HTML</code>". </li>
<li> The public identifier starts with: "<code title="">+//Silmaril//dtd html Pro v0r11 19970101//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//AdvaSoft Ltd//DTD HTML 3.0 asWedit + extensions//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//AS//DTD HTML 3.0 asWedit + extensions//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 2.0 Level 1//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 2.0 Level 2//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 2.0 Strict Level 1//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 2.0 Strict Level 2//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 2.0 Strict//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 2.0//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 2.1E//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 3.0//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML 3.0//EN//</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 3.2 Final//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 3.2//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML 3//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Level 0//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Level 0//EN//2.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Level 1//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Level 1//EN//2.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Level 2//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Level 2//EN//2.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Level 3//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Level 3//EN//3.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Strict Level 0//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Strict Level 0//EN//2.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Strict Level 1//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Strict Level 1//EN//2.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Strict Level 2//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Strict Level 2//EN//2.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Strict Level 3//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Strict Level 3//EN//3.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML Strict//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Strict//EN//2.0</code>" </li>-->
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML Strict//EN//3.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//IETF//DTD HTML//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML//EN//2.0</code>" </li>-->
<!--<li> The public identifier is set to: "<code title="">-//IETF//DTD HTML//EN//3.0</code>" </li>-->
<li> The public identifier starts with: "<code title="">-//Metrius//DTD Metrius Presentational//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Microsoft//DTD Internet Explorer 2.0 HTML Strict//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Microsoft//DTD Internet Explorer 2.0 HTML//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Microsoft//DTD Internet Explorer 2.0 Tables//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Microsoft//DTD Internet Explorer 3.0 HTML Strict//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Microsoft//DTD Internet Explorer 3.0 HTML//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Microsoft//DTD Internet Explorer 3.0 Tables//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Netscape Comm. Corp.//DTD HTML//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Netscape Comm. Corp.//DTD Strict HTML//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//O'Reilly and Associates//DTD HTML 2.0//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//O'Reilly and Associates//DTD HTML Extended 1.0//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//O'Reilly and Associates//DTD HTML Extended Relaxed 1.0//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//SoftQuad Software//DTD HoTMetaL PRO 6.0::19990601::extensions to HTML 4.0//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//SoftQuad//DTD HoTMetaL PRO 4.0::19971010::extensions to HTML 4.0//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Spyglass//DTD HTML 2.0 Extended//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//SQ//DTD HTML 2.0 HoTMetaL + extensions//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Sun Microsystems Corp.//DTD HotJava HTML//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//Sun Microsystems Corp.//DTD HotJava Strict HTML//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML 3 1995-03-24//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML 3.2 Draft//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML 3.2 Final//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML 3.2//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML 3.2S Draft//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML 4.0 Frameset//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML 4.0 Transitional//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML Experimental 19960712//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD HTML Experimental 970421//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD W3 HTML//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3O//DTD W3 HTML 3.0//<!--EN--></code>" </li>
<!--<li> The public identifier is set to: "<code title="">-//W3O//DTD W3 HTML 3.0//EN//</code>" </li>-->
<li> The public identifier is set to: "<code title="">-//W3O//DTD W3 HTML Strict 3.0//EN//</code>" </li>
<li> The public identifier starts with: "<code title="">-//WebTechs//DTD Mozilla HTML 2.0//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//WebTechs//DTD Mozilla HTML//<!--EN--></code>" </li>
<li> The public identifier is set to: "<code title="">-/W3C/DTD HTML 4.0 Transitional/EN</code>" </li>
<li> The public identifier is set to: "<code title="">HTML</code>" </li>
<li> The system identifier is set to: "<code title="">http://www.ibm.com/data/dtd/v11/ibmxhtml1-transitional.dtd</code>" </li>
<li> The system identifier is missing and the public identifier starts with: "<code title="">-//W3C//DTD HTML 4.01 Frameset//<!--EN--></code>" </li>
<li> The system identifier is missing and the public identifier starts with: "<code title="">-//W3C//DTD HTML 4.01 Transitional//<!--EN--></code>" </li>
</ul>
<p>Otherwise, if the DOCTYPE token matches one of the conditions
in the following list, then set the <code>Document</code> to
<span>limited quirks mode</span>:</p>
<ul class="brief">
<li> The public identifier starts with: "<code title="">-//W3C//DTD XHTML 1.0 Frameset//<!--EN--></code>" </li>
<li> The public identifier starts with: "<code title="">-//W3C//DTD XHTML 1.0 Transitional//<!--EN--></code>" </li>
<li> The system identifier is not missing and the public identifier starts with: "<code title="">-//W3C//DTD HTML 4.01 Frameset//<!--EN--></code>" </li>
<li> The system identifier is not missing and the public identifier starts with: "<code title="">-//W3C//DTD HTML 4.01 Transitional//<!--EN--></code>" </li>
</ul>
<p>The name, system identifier, and public identifier strings must
be compared to the values given in the lists above in an
<span>ASCII case-insensitive</span> manner. A system identifier
whose value is the empty string is not considered missing for the
purposes of the conditions above.</p>
<p>Then, switch the <span>insertion mode</span> to "<span
title="insertion mode: before html">before html</span>".</p>
</dd>
<dt>Anything else</dt>
<dd>
<p><span>Parse error</span>.</p>
<p>Set the <code>Document</code> to <span>quirks mode</span>.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: before html">before html</span>", then
reprocess the current token.</p>
</dd>
</dl>
<h5>The "<dfn title="insertion mode: before html">before html</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: before html">before html</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <code>Document</code>
object with the <code title="">data</code> attribute set to the
data given in the comment token.</p>
</dd>
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p>Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p><span>Create an element for the token</span> in the <span>HTML
namespace</span>. Append it to the <code>Document</code>
object. Put this element in the <span>stack of open
elements</span>.</p>
<p id="parser-appcache">If the <code>Document</code> is being
loaded as part of <span title="navigate">navigation</span> of a
<span>browsing context</span>, then: if the newly created element
has a <code title="attr-html-manifest">manifest</code> attribute,
then <span title="resolve a url">resolve</span> the value of that
attribute to an <span>absolute URL</span>, relative to the newly
created element, and if that is successful, run the <span
title="concept-appcache-init">application cache selection
algorithm</span> with the resulting <span>absolute URL</span> with
any <span title="url-fragment"><fragment></span> component
removed; otherwise, if there is no such attribute or resolving it
fails, run the <span title="concept-appcache-init">application
cache selection algorithm</span> with no manifest. The algorithm
must be passed the <code>Document</code> object.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: before head">before head</span>".</p>
</dd>
<dt>An end tag whose tag name is one of: "head", "body", "html", "br"</dt>
<dd>
<p>Act as described in the "anything else" entry below.</p>
</dd>
<dt>Any other end tag</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Create an <code>html</code> element. Append it to the
<code>Document</code> object. Put this element in the <span>stack
of open elements</span>.</p>
<p>If the <code>Document</code> is being loaded as part of <span
title="navigate">navigation</span> of a <span>browsing
context</span>, then: run the <span
title="concept-appcache-init">application cache selection
algorithm</span> with no manifest, passing it the
<code>Document</code> object.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: before head">before head</span>", then
reprocess the current token.</p>
</dd>
</dl>
<p>The root element can end up being removed from the
<code>Document</code> object, e.g. by scripts; nothing in particular
happens in such cases, content continues being appended to the nodes
as described in the next section.</p>
<h5>The "<dfn title="insertion mode: before head">before head</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: before head">before head</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p>Ignore the token.</p> <!-- :-( -->
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A start tag whose tag name is "head"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Set the <span><code title="">head</code> element pointer</span>
to the newly created <code>head</code> element.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in head">in head</span>".</p>
</dd>
<dt>An end tag whose tag name is one of: "head", "body", "html", "br"</dt>
<dd>
<p>Act as if a start tag token with the tag name "head" and no
attributes had been seen, then reprocess the current token.</p>
</dd>
<dt>Any other end tag</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Act as if a start tag token with the tag name "head" and no
attributes had been seen, then reprocess the current
token.</p>
</dd>
</dl>
<h5 id="parsing-main-inhead">The "<dfn title="insertion mode: in head">in head</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in head">in head</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p><span title="insert a character">Insert the character</span> into
the <span>current node</span>.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A start tag whose tag name is one of: "base", "command",
"link"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token. Immediately
pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p><span title="acknowledge self-closing flag">Acknowledge the
token's <i>self-closing flag</i></span>, if it is set.</p>
</dd>
<dt>A start tag whose tag name is "meta"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token. Immediately
pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p><span title="acknowledge self-closing flag">Acknowledge the
token's <i>self-closing flag</i></span>, if it is set.</p>
<p id="meta-charset-during-parse">If the element has a <code
title="attr-meta-charset">charset</code> attribute, and its
value is a supported encoding, and the <span
title="concept-encoding-confidence">confidence</span> is
currently <i>tentative</i>, then <span>change the
encoding</span> to the encoding given by the value of the
<code title="attr-meta-charset">charset</code> attribute.</p>
<p>Otherwise, if the element has a <code
title="attr-meta-charset">content</code> attribute, and
applying the <span>algorithm for extracting an encoding from a
Content-Type</span> to its value returns a supported encoding
<var title="">encoding</var>, and the <span
title="concept-encoding-confidence">confidence</span> is
currently <i>tentative</i>, then <span>change the
encoding</span> to the encoding <var
title="">encoding</var>.</p>
</dd>
<dt>A start tag whose tag name is "title"</dt>
<dd>
<p>Follow the <span>generic RCDATA element parsing algorithm</span>.</p>
</dd>
<dt>A start tag whose tag name is "noscript", if the <span>scripting flag</span> is enabled</dt>
<dt>A start tag whose tag name is one of: "noframes", "style"</dt>
<dd>
<p>Follow the <span>generic raw text element parsing algorithm</span>.</p>
</dd>
<dt>A start tag whose tag name is "noscript", if the <span>scripting flag</span> is disabled</dt>
<dd>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in head noscript">in head
noscript</span>".</p>
</dd>
<dt id="scriptTag">A start tag whose tag name is "script"</dt>
<dd>
<ol>
<li><p><span>Create an element for the token</span> in the
<span>HTML namespace</span>.</p></li>
<li>
<p>Mark the element as being <span>"parser-inserted"</span>.</p>
<p class="note">This ensures that, if the script is external,
any <code title="dom-document-write">document.write()</code>
calls in the script will execute in-line, instead of blowing the
document away, as would happen in most other cases. It also
prevents the script from executing until the end tag is
seen.</p>
</li>
<li><p>If the parser was originally created for the <span>HTML
fragment parsing algorithm</span>, then mark the
<code>script</code> element as <span>"already
started"</span>. (<span>fragment case</span>)</p></li>
<li><p>Append the new element to the <span>current node</span>
and push it onto the <span>stack of open
elements</span>.</p></li>
<li><p>Switch the tokenizer to the <span>script data
state</span>.</p></li>
<li><p>Let the <span>original insertion mode</span> be the current
<span>insertion mode</span>.</p>
<li><p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: text">text</span>".</p></li>
</ol>
</dd>
<dt>An end tag whose tag name is "head"</dt>
<dd>
<p>Pop the <span>current node</span> (which will be the
<code>head</code> element) off the <span>stack of open
elements</span>.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: after head">after head</span>".</p>
</dd>
<dt>An end tag whose tag name is one of: "body", "html", "br"</dt>
<dd>
<p>Act as described in the "anything else" entry below.</p>
</dd>
<dt>A start tag whose tag name is "head"</dt>
<dt>Any other end tag</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<!-- can't get here with an EOF and a fragment case -->
<p>Act as if an end tag token with the tag name "head" had
been seen, and reprocess the current token.</p>
</dd>
</dl>
<h5 id="parsing-main-inheadnoscript">The "<dfn title="insertion mode: in head noscript">in head noscript</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in head noscript">in head noscript</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end tag whose tag name is "noscript"</dt>
<dd>
<p>Pop the <span>current node</span> (which will be a
<code>noscript</code> element) from the <span>stack of open
elements</span>; the new <span>current node</span> will be a
<code>head</code> element.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in head">in head</span>".</p>
</dd>
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dt>A comment token</dt>
<dt>A start tag whose tag name is one of: "link", "meta", "noframes", "style"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in head">in head</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end tag whose tag name is "br"</dt>
<dd>
<p>Act as described in the "anything else" entry below.</p>
</dd>
<dt>A start tag whose tag name is one of: "head", "noscript"</dt>
<dt>Any other end tag</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<!-- can't get here with an EOF and a fragment case -->
<p><span>Parse error</span>. Act as if an end tag with the tag
name "noscript" had been seen and reprocess the current
token.</p>
</dd>
</dl>
<h5>The "<dfn title="insertion mode: after head">after head</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: after head">after head</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p><span title="insert a character">Insert the character</span> into
the <span>current node</span>.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A start tag whose tag name is "body"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in body">in body</span>".</p>
</dd>
<dt>A start tag whose tag name is "frameset"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in frameset">in frameset</span>".</p>
</dd>
<dt>A start tag token whose tag name is one of: "base", "link",
"meta", "noframes", "script", "style", "title"</dt>
<dd>
<p><span>Parse error</span>.</p>
<p>Push the node pointed to by the <span><code
title="">head</code> element pointer</span> onto the
<span>stack of open elements</span>.</p>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in head">in head</span>" <span>insertion
mode</span>.</p>
<p>Remove the node pointed to by the <span><code
title="">head</code> element pointer</span> from the <span>stack
of open elements</span>.</p>
<p class="note">The <span><code title="">head</code> element
pointer</span> cannot be null at this point.</p>
</dd>
<dt>An end tag whose tag name is one of: "body", "html", "br"</dt>
<dd>
<p>Act as described in the "anything else" entry below.</p>
</dd>
<dt>A start tag whose tag name is "head"</dt>
<dt>Any other end tag</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Act as if a start tag token with the tag name "body" and no
attributes had been seen, then set the <span>frameset-ok
flag</span> back to "ok", and then reprocess the current
token.</p>
</dd>
</dl>
<h5 id="parsing-main-inbody">The "<dfn title="insertion mode: in body">in body</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in body">in body</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span title="insert a character">Insert the token's
character</span> into the <span>current node</span>.</p>
<p>If the token is not one of U+0009 CHARACTER TABULATION, U+000A
LINE FEED (LF), U+000C FORM FEED (FF), <!--U+000D CARRIAGE RETURN
(CR),--> or U+0020 SPACE, then set the <span>frameset-ok
flag</span> to "not ok".</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p><span>Parse error</span>. For each attribute on the token,
check to see if the attribute is already present on the top
element of the <span>stack of open elements</span>. If it is not,
add the attribute and its corresponding value to that element.</p>
</dd>
<dt>A start tag token whose tag name is one of: "base", "command",
"link", "meta", "noframes", "script", "style", "title"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in head">in head</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A start tag whose tag name is "body"</dt>
<dd>
<p><span>Parse error</span>.</p>
<p>If the second element on the <span>stack of open
elements</span> is not a <code>body</code> element, or, if the
<span>stack of open elements</span> has only one node on it,
then ignore the token. (<span>fragment case</span>)</p>
<p>Otherwise, for each attribute on the token, check to see if
the attribute is already present on the <code>body</code>
element (the second element) on the <span>stack of open
elements</span>. If it is not, add the attribute and its
corresponding value to that element.</p>
</dd>
<dt>A start tag whose tag name is "frameset"</dt>
<dd>
<p><span>Parse error</span>.</p>
<p>If the second element on the <span>stack of open
elements</span> is not a <code>body</code> element, or, if the
<span>stack of open elements</span> has only one node on it,
then ignore the token. (<span>fragment case</span>)</p>
<p>If the <span>frameset-ok flag</span> is set to "not ok", ignore
the token.</p>
<p>Otherwise, run the following steps:</p>
<ol>
<li><p>Remove the second element on the <span>stack of open
elements</span> from its parent node, if it has one.</p></li>
<li><p>Pop all the nodes from the bottom of the <span>stack of
open elements</span>, from the <span>current node</span> up to,
but not including, the root <code>html</code> element.</p>
<li><p><span>Insert an HTML element</span> for the
token.</p></li>
<li><p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in frameset">in frameset</span>".</p>
</ol>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p>If there is a node in the <span>stack of open elements</span>
that is not either a <code>dd</code> element, a <code>dt</code>
element, an <code>li</code> element, a <code>p</code> element, a
<code>tbody</code> element, a <code>td</code> element, a
<code>tfoot</code> element, a <code>th</code> element, a
<code>thead</code> element, a <code>tr</code> element, the
<code>body</code> element, or the <code>html</code> element, then
this is a <span>parse error</span>.</p> <!-- (some of those are
fragment cases) -->
<p><span>Stop parsing</span>.</p>
</dd>
<dt>An end tag whose tag name is "body"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in scope">have a <code>body</code> element
in scope</span>, this is a <span>parse error</span>; ignore the
token.</p>
<!-- if we get here, the insertion mode here is forcibly "in
body". -->
<p>Otherwise, if there is a node in the <span>stack of open
elements</span> that is not either a <code>dd</code> element, a
<code>dt</code> element, an <code>li</code> element, an
<code>optgroup</code> element, an <code>option</code> element, a
<code>p</code> element, an <code>rp</code> element, an
<code>rt</code> element, a <code>tbody</code> element, a
<code>td</code> element, a <code>tfoot</code> element, a
<code>th</code> element, a <code>thead</code> element, a
<code>tr</code> element, the <code>body</code> element, or the
<code>html</code> element, then this is a <span>parse
error</span>.</p> <!-- (some of those are fragment cases, e.g. for
<tbody> you'd have hit the first paragraph since the <body>
wouldn't be in scope, unless it was a fragment case) -->
<!-- If we ever change the frameset-ok flag to an insertion mode,
then we'd have to somehow keep track of its state when we switch
to after-body. -->
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: after body">after body</span>".</p>
</dd>
<dt>An end tag whose tag name is "html"</dt>
<dd>
<p>Act as if an end tag with tag name "body" had been seen,
then, if that token wasn't ignored, reprocess the current
token.</p>
<p class="note">The fake end tag token here can only be
ignored in the <span>fragment case</span>.</p>
</dd>
<!-- start tags for non-phrasing flow content elements -->
<!-- the normal ones -->
<dt>A start tag whose tag name is one of: "address", "article",
"aside", "blockquote", "center", <!--v2DATAGRID-->"datagrid",
"details", "dir", "div", "dl", "fieldset", "figure", "footer",
"header", "hgroup", "menu", "nav", "ol", "p", "section", "ul"</dt>
<dd>
<!-- As of May 2008 this doesn't match any browser exactly, but is
as close to what IE does as I can get without doing the non-tree
DOM nonsense, and thus should actually afford better compatibility
when implemented by the other browsers. -->
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p><span>Insert an HTML element</span> for the token.</p>
</dd>
<!-- as normal, but close h1-h6 if it's the current node -->
<dt>A start tag whose tag name is one of: "h1", "h2", "h3", "h4",
"h5", "h6"</dt>
<dd>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p>If the <span>current node</span> is an element whose tag name
is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a
<span>parse error</span>; pop the <span>current node</span> off
the <span>stack of open elements</span>.</p>
<!-- See https://bugs.webkit.org/show_bug.cgi?id=12646 -->
<p><span>Insert an HTML element</span> for the token.</p>
</dd>
<!-- as normal, but drops leading newline -->
<dt>A start tag whose tag name is one of: "pre", "listing"</dt>
<dd>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p><span>Insert an HTML element</span> for the token.</p>
<p>If the next token is a U+000A LINE FEED (LF) character
token, then ignore that token and move on to the next
one. (Newlines at the start of <code>pre</code> blocks are
ignored as an authoring convenience.)</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
</dd>
<!-- as normal, but interacts with the form element pointer -->
<dt>A start tag whose tag name is "form"</dt>
<dd>
<p>If the <span><code title="form">form</code> element
pointer</span> is not null, then this is a <span>parse
error</span>; ignore the token.</p>
<p>Otherwise:</p>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p><span>Insert an HTML element</span> for the token, and set the
<span><code title="form">form</code> element pointer</span> to
point to the element created.</p>
</dd>
<!-- as normal, but imply </li> when there's another <li> open in weird cases -->
<dt>A start tag whose tag name is "li"</dt>
<dd>
<p>Run the following algorithm:</p>
<ol>
<li><p>Set the <span>frameset-ok flag</span> to "not ok".</p></li>
<li><p>Initialize <var title="">node</var> to be the <span>current
node</span> (the bottommost node of the stack).</p></li>
<li><p><i>Loop</i>: If <var title="">node</var> is an
<code>li</code> element, then act as if an end tag with the tag
name "li" had been seen, then jump to the last step.</p></li>
<li><p>If <var title="">node</var> is not in the
<span>formatting</span> category, and is not in the
<span>phrasing</span> category, and is not an
<code>address</code>, <code>div</code>, or <code>p</code>
element, then jump to the last step.</p></li> <!-- an element
<foo> is in this list if the following markup:
<!DOCTYPE html><body><ol><li><foo><li>
...results in the second <li> not being (in any way) a descendant
of the first <li>, or if <foo> is a formatting element that gets
reopened later. -->
<li><p>Otherwise, set <var title="">node</var> to the previous
entry in the <span>stack of open elements</span> and return to
the step labeled <i>loop</i>.</p></li>
<li>
<p>This is the last step.</p>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p>Finally, <span>insert an HTML element</span> for the
token.</p>
</li>
</ol>
</dd>
<!-- as normal, but imply </dt> or </dd> when there's another <dt> or <dd> open in weird cases -->
<dt>A start tag whose tag name is one of: "dd", "dt"</dt>
<dd>
<p>Run the following algorithm:</p>
<ol>
<li><p>Set the <span>frameset-ok flag</span> to "not ok".</p></li>
<li><p>Initialize <var title="">node</var> to be the <span>current
node</span> (the bottommost node of the stack).</p></li>
<li><p><i>Loop</i>: If <var title="">node</var> is a
<code>dd</code> or <code>dt</code> element, then act as if an end
tag with the same tag name as <var title="">node</var> had been
seen, then jump to the last step.</p></li>
<li><p>If <var title="">node</var> is not in the
<span>formatting</span> category, and is not in the
<span>phrasing</span> category, and is not an
<code>address</code>, <code>div</code>, or <code>p</code>
element, then jump to the last step.</p></li> <!-- an element
<foo> is in this list if the following markup:
<!DOCTYPE html><body><dl><dt><foo><dt>
...results in the second <dt> not being (in any way) a descendant
of the first <dt>, or if <foo> is a formatting element that gets
reopened later. -->
<li><p>Otherwise, set <var title="">node</var> to the previous
entry in the <span>stack of open elements</span> and return to
the step labeled <i>loop</i>.</p></li>
<li>
<p>This is the last step.</p>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p>Finally, <span>insert an HTML element</span> for the
token.</p>
</li>
</ol>
</dd>
<!-- same as normal, but effectively ends parsing -->
<dt>A start tag whose tag name is "plaintext"</dt>
<dd>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Switch the tokenizer to the <span>PLAINTEXT state</span>.</p>
<p class="note">Once a start tag with the tag name "plaintext" has
been seen, that will be the last token ever seen other than
character tokens (and the end-of-file token), because there is no
way to switch out of the <span>PLAINTEXT state</span>.</p>
</dd>
<!-- end tags for non-phrasing flow content elements -->
<!-- the normal ones -->
<dt>An end tag whose tag name is one of: "address", "article",
"aside", "blockquote", "center", <!--v2DATAGRID-->"datagrid",
"details", "dir", "div", "dl", "fieldset", "figure", "footer",
"header", "hgroup", "listing", "menu", "nav", "ol", "pre",
"section", "ul"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in scope">have an element in scope</span>
with the same tag name as that of the token, then this is a
<span>parse error</span>; ignore the token.</p>
<p>Otherwise, run these steps:</p>
<ol>
<li><p><span>Generate implied end tags</span>.</p></li>
<li><p>If the <span>current node</span> is not an element with
the same tag name as that of the token, then this is a
<span>parse error</span>.</p></li>
<li><p>Pop elements from the <span>stack of open elements</span>
until an element with the same tag name as the token has been
popped from the stack.</p></li>
</ol>
</dd>
<!-- removes the form element pointer instead of the matching node -->
<dt>An end tag whose tag name is "form"</dt>
<dd>
<p>Let <var title="">node</var> be the element that the
<span><code title="">form</code> element pointer</span> is set
to.</p>
<p>Set the <span><code title="">form</code> element pointer</span>
to null.</p>
<p>If <var title="">node</var> is null or the <span>stack of open
elements</span> does not <span title="has an element in
scope">have <var title="">node</var> in scope</span>, then this is
a <span>parse error</span>; ignore the token.</p>
<p>Otherwise, run these steps:</p>
<ol>
<li><p><span>Generate implied end tags</span>.</p></li>
<li><p>If the <span>current node</span> is not <var
title="">node</var>, then this is a <span>parse
error</span>.</p></li>
<li><p>Remove <var title="">node</var> from the <span>stack of
open elements</span>.</p></li>
</ol>
</dd>
<!-- as normal, except </p> implies <p> if there's no <p> in scope, and needs care as the elements have optional tags -->
<dt>An end tag whose tag name is "p"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in scope">have an element in scope</span>
with the same tag name as that of the token, then this is a
<span>parse error</span>; act as if a start tag with the tag name
"p" had been seen, then reprocess the current token.</p>
<p>Otherwise, run these steps:</p>
<ol>
<li><p><span>Generate implied end tags</span>, except
for elements with the same tag name as the token.</p></li>
<li><p>If the <span>current node</span> is not an element with
the same tag name as that of the token, then this is a
<span>parse error</span>.</p></li>
<li><p>Pop elements from the <span>stack of open elements</span>
until an element with the same tag name as the token has been
popped from the stack.</p></li>
</ol>
</dd>
<!-- as normal, but needs care as the elements have optional tags, and are further scoped by <ol>/<ul> -->
<dt>An end tag whose tag name is "li"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in list item scope">have an element in list
item scope</span> with the same tag name as that of the token,
then this is a <span>parse error</span>; ignore the token.</p>
<p>Otherwise, run these steps:</p>
<ol>
<li><p><span>Generate implied end tags</span>, except
for elements with the same tag name as the token.</p></li>
<li><p>If the <span>current node</span> is not an element with
the same tag name as that of the token, then this is a
<span>parse error</span>.</p></li>
<li><p>Pop elements from the <span>stack of open elements</span>
until an element with the same tag name as the token has been
popped from the stack.</p></li>
</ol>
</dd>
<!-- as normal, but needs care as the elements have optional tags -->
<dt>An end tag whose tag name is one of: "dd", "dt"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in scope">have an element in scope</span>
with the same tag name as that of the token, then this is a
<span>parse error</span>; ignore the token.</p>
<p>Otherwise, run these steps:</p>
<ol>
<li><p><span>Generate implied end tags</span>, except
for elements with the same tag name as the token.</p></li>
<li><p>If the <span>current node</span> is not an element with
the same tag name as that of the token, then this is a
<span>parse error</span>.</p></li>
<li><p>Pop elements from the <span>stack of open elements</span>
until an element with the same tag name as the token has been
popped from the stack.</p></li>
</ol>
</dd>
<!-- as normal, except acts as a closer for any of the h1-h6 elements -->
<dt>An end tag whose tag name is one of: "h1", "h2", "h3", "h4", "h5", "h6"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in scope">have an element in scope</span>
whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6",
then this is a <span>parse error</span>; ignore the token.</p>
<p>Otherwise, run these steps:</p>
<ol>
<li><p><span>Generate implied end tags</span>.</p></li>
<li><p>If the <span>current node</span> is not an element with
the same tag name as that of the token, then this is a
<span>parse error</span>.</p></li>
<li><p>Pop elements from the <span>stack of open elements</span>
until an element whose tag name is one of "h1", "h2", "h3", "h4",
"h5", or "h6" has been popped from the stack.</p></li>
</ol>
</dd>
<dt>An end tag whose tag name is "sarcasm"</dt>
<dd>
<p>Take a deep breath, then act as described in the "any other end
tag" entry below.</p>
</dd>
<!-- ADOPTION AGENCY ELEMENTS
Mozilla-only: bdo blink del ins sub sup q
Safari-only: code dfn kbd nobr samp var wbr
Both: a b big em font i s small strike strong tt u -->
<dt>A start tag whose tag name is "a"</dt>
<dd>
<p>If the <span>list of active formatting elements</span>
contains an element whose tag name is "a" between the end of
the list and the last marker on the list (or the start of the
list if there is no marker on the list), then this is a
<span>parse error</span>; act as if an end tag with the tag
name "a" had been seen, then remove that element from the
<span>list of active formatting elements</span> and the
<span>stack of open elements</span> if the end tag didn't
already remove it (it might not have if the element is not
<span title="has an element in table scope">in table
scope</span>).</p>
<p class="example">In the non-conforming stream
<code><a href="a">a<table><a href="b">b</table>x</code>,
the first <code>a</code> element would be closed upon seeing
the second one, and the "x" character would be inside a link
to "b", not to "a". This is despite the fact that the outer
<code>a</code> element is not in table scope (meaning that a
regular <code></a></code> end tag at the start of the table
wouldn't close the outer <code>a</code> element).</p>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token. Add that
element to the <span>list of active formatting
elements</span>.</p>
</dd>
<dt>A start tag whose tag name is one of: "b", "big", "code", "em",
"font", "i", "s", "small", "strike", "strong", "tt", "u"</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token. Add that
element to the <span>list of active formatting
elements</span>.</p>
</dd>
<dt>A start tag whose tag name is "nobr"</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p>If the <span>stack of open elements</span> <span title="has an
element in scope">has a <code>nobr</code> element in scope</span>,
then this is a <span>parse error</span>; act as if an end tag with
the tag name "nobr" had been seen, then once again
<span>reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token. Add that
element to the <span>list of active formatting
elements</span>.</p>
</dd>
<dt id="adoptionAgency">An end tag whose tag name is one of: "a",
"b", "big", "code", "em", "font", "i", "nobr", "s", "small",
"strike", "strong", "tt", "u"</dt>
<dd>
<p>Follow these steps:</p>
<ol>
<li>
<p>Let the <var title="">formatting element</var> be the
last element in the <span>list of active formatting
elements</span> that:</p>
<ul>
<li>is between the end of the list and the last scope
marker in the list, if any, or the start of the list
otherwise, and</li>
<li>has the same tag name as the token.</li>
</ul>
<p>If there is no such node, or, if that node is also in the
<span>stack of open elements</span> but the element is not <span
title="has an element in scope">in scope</span>, then this is a
<span>parse error</span>; ignore the token, and abort these
steps.</p>
<p>Otherwise, if there is such a node, but that node is not
in the <span>stack of open elements</span>, then this is a
<span>parse error</span>; remove the element from the list,
and abort these steps.</p>
<p>Otherwise, there is a <var title="">formatting
element</var> and that element is in <span title="stack of
open elements">the stack</span> and is <span title="has an
element in scope">in scope</span>. If the element is not the
<span>current node</span>, this is a <span>parse
error</span>. In any case, proceed with the algorithm as
written in the following steps.</p>
</li>
<li><p>Let the <var title="">furthest block</var> be the
topmost node in the <span>stack of open elements</span> that
is lower in the stack than the <var title="">formatting
element</var>, and is not an element in the
<span>phrasing</span> or <span>formatting</span>
categories. There might not be one.</p></li>
<li><p>If there is no <var title="">furthest block</var>,
then the UA must skip the subsequent steps and instead just
pop all the nodes from the bottom of the <span>stack of open
elements</span>, from the <span>current node</span> up to and
including the <var title="">formatting element</var>, and
remove the <var title="">formatting element</var> from the
<span>list of active formatting elements</span>.</p></li>
<li><p>Let the <var title="">common ancestor</var> be the element
immediately above the <var title="">formatting element</var> in the
<span>stack of open elements</span>.</p></li>
<li><p>Let a bookmark note the position of the <var
title="">formatting element</var> in the <span>list of active
formatting elements</span> relative to the elements on either
side of it in the list.</p></li>
<li>
<p>Let <var title="">node</var> and <var title="">last node</var> be the
<var title="">furthest block</var>. Follow these steps:</p>
<ol>
<li>Let <var title="">node</var> be the element immediately
above <var title="">node</var> in the <span>stack of open
elements</span>, or if <var title="">node</var> is no longer in
the <span>stack of open elements</span> (e.g. because it got
removed by the next step), the element that was immediately
above <var title="">node</var> in the <span>stack of open
elements</span> before <var title="">node</var> was
removed.</li>
<li>If <var title="">node</var> is not in the <span>list of
active formatting elements</span>, then remove <var
title="">node</var> from the <span>stack of open
elements</span> and then go back to step 1.</li>
<li>Otherwise, if <var title="">node</var> is the <var
title="">formatting element</var>, then go to the next step
in the overall algorithm.</li>
<li>Otherwise, if <var title="">last node</var> is the <var
title="">furthest block</var>, then move the aforementioned
bookmark to be immediately after the <var
title="">node</var> in the <span>list of active formatting
elements</span>.</li>
<li><span>Create an element for the token</span> for which the
element <var title="">node</var> was created, replace the entry
for <var title="">node</var> in the <span>list of active
formatting elements</span> with an entry for the new element,
replace the entry for <var title="">node</var> in the
<span>stack of open elements</span> with an entry for the new
element, and let <var title="">node</var> be the new
element.</li>
<li>Insert <var title="">last node</var> into <var
title="">node</var>, first removing it from its previous
parent node if any.</li>
<li>Let <var title="">last node</var> be <var title="">node</var>.</li>
<li>Return to step 1 of this inner set of steps.</li>
</ol>
</li>
<li>
<p>If the <var title="">common ancestor</var> node is a
<code>table</code>, <code>tbody</code>, <code>tfoot</code>,
<code>thead</code>, or <code>tr</code> element, then,
<span>foster parent</span> whatever <var title="">last
node</var> ended up being in the previous step, first removing
it from its previous parent node if any.</p>
<p>Otherwise, append whatever <var title="">last node</var>
ended up being in the previous step to the <var title="">common
ancestor</var> node, first removing it from its previous parent
node if any.</p>
</li>
<li><p><span>Create an element for the token</span> for which the
<var title="">formatting element</var> was created.</p></li>
<li><p>Take all of the child nodes of the <var title="">furthest
block</var> and append them to the element created in the last
step.</p></li>
<li><p>Append that new element to the <var title="">furthest
block</var>.</p></li>
<li><p>Remove the <var title="">formatting element</var> from the
<span>list of active formatting elements</span>, and insert the
new element into the <span>list of active formatting
elements</span> at the position of the aforementioned
bookmark.</p></li>
<li><p>Remove the <var title="">formatting element</var> from the
<span>stack of open elements</span>, and insert the new element
into the <span>stack of open elements</span> immediately below
the position of the <var title="">furthest block</var> in that
stack.</p></li>
<li><p>Jump back to step 1 in this series of steps.</p></li>
</ol>
<p class="note">Because of the way this algorithm causes elements
to change parents, it has been dubbed the "adoption agency
algorithm" (in contrast with other possible algorithms for dealing
with misnested content, which included the "incest algorithm", the
"secret affair algorithm", and the "Heisenberg algorithm").</p>
</dd>
<dt>A start tag whose tag name is "button"</dt>
<dd>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>button</code> element in
scope</span>, then this is a <span>parse error</span>;
act as if an end tag with the tag name "button" had been seen,
then reprocess the token.</p>
<p>Otherwise:</p>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Insert a marker at the end of the <span>list of active
formatting elements</span>.</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
</dd>
<dt>A start tag token whose tag name is one of: "applet",
"marquee", "object"</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Insert a marker at the end of the <span>list of active
formatting elements</span>.</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
</dd>
<dt>An end tag token whose tag name is one of: "applet", "button",
"marquee", "object"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in scope">have an element in scope</span>
with the same tag name as that of the token, then this is a
<span>parse error</span>; ignore the token.</p>
<p>Otherwise, run these steps:</p>
<ol>
<li><p><span>Generate implied end tags</span>.</p></li>
<li><p>If the <span>current node</span> is not an element with
the same tag name as that of the token, then this is a
<span>parse error</span>.</p></li>
<li><p>Pop elements from the <span>stack of open elements</span>
until an element with the same tag name as the token has been
popped from the stack.</p></li>
<li><span>Clear the list of active formatting elements up to the
last marker</span>.</li>
</ol>
</dd>
<dt>A start tag whose tag name is "table"</dt>
<dd>
<p>If the <code>Document</code> is <em>not</em> set to
<span>quirks mode</span>, and the <span>stack of open
elements</span> <span title="has an element in scope">has a
<code>p</code> element in scope</span>, then act as if an end tag
with the tag name "p" had been seen.</p> <!-- i hate myself (this
quirk was basically caused by acid2; if i'd realised we could
change the specs when i wrote acid2, we could have avoided having
any parsing-mode quirks) -Hixie -->
<p><span>Insert an HTML element</span> for the token.</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in table">in table</span>".</p>
</dd>
<dt>A start tag whose tag name is one of: "area", "basefont",
"bgsound", "br", "embed", "img", "input", "keygen", "wbr"</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token. Immediately
pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p><span title="acknowledge self-closing flag">Acknowledge the
token's <i>self-closing flag</i></span>, if it is set.</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p> <!--
shouldn't really do it for <area>, <basefont>, and <bgsound> -->
</dd>
<dt>A start tag whose tag name is one of: "param", "source"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token. Immediately
pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p><span title="acknowledge self-closing flag">Acknowledge the
token's <i>self-closing flag</i></span>, if it is set.</p>
</dd>
<dt>A start tag whose tag name is "hr"</dt>
<dd>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p><span>Insert an HTML element</span> for the token. Immediately
pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p><span title="acknowledge self-closing flag">Acknowledge the
token's <i>self-closing flag</i></span>, if it is set.</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
</dd>
<dt>A start tag whose tag name is "image"</dt>
<dd>
<p><span>Parse error</span>. Change the token's tag name
to "img" and reprocess it. (Don't ask.)</p> <!-- As of
2005-12, studies showed that around 0.2% of pages used the
<image> element. -->
</dd>
<dt id="isindex">A start tag whose tag name is "isindex"</dt>
<dd>
<p><span>Parse error</span>.</p>
<p>If the <span><code title="">form</code> element
pointer</span> is not null, then ignore the token.</p>
<p>Otherwise:</p>
<p><span title="acknowledge self-closing flag">Acknowledge the
token's <i>self-closing flag</i></span>, if it is set.</p> <!--
purely to reduce the number of errors (we don't care if they
included the /, they're not supposed to be including the tag at
all! -->
<p>Act as if a start tag token with the tag name "form" had been seen.</p>
<p>If the token has an attribute called "action", set the
<code title="attr-form-action">action</code> attribute on the
resulting <code>form</code> element to the value of the
"action" attribute of the token.</p>
<p>Act as if a start tag token with the tag name "hr" had been
seen.</p>
<p>Act as if a start tag token with the tag name "label" had been
seen.</p>
<p>Act as if a stream of character tokens had been seen (see below
for what they should say).</p>
<p>Act as if a start tag token with the tag name "input" had been
seen, with all the attributes from the "isindex" token except
"name", "action", and "prompt". Set the <code
title="attr-fe-name">name</code> attribute of the resulting
<code>input</code> element to the value "<code
title="">isindex</code>".</p>
<p>Act as if a stream of character tokens had been seen (see
below for what they should say).</p>
<p>Act as if an end tag token with the tag name "label" had been
seen.</p>
<p>Act as if a start tag token with the tag name "hr" had been
seen.</p>
<p>Act as if an end tag token with the tag name "form" had been
seen.</p>
<p>If the token has an attribute with the name "prompt", then the
first stream of characters must be the same string as given in
that attribute, and the second stream of characters must be
empty. Otherwise, the two streams of character tokens together
should, together with the <code>input</code> element, express the
equivalent of "This is a searchable index. Insert your search
keywords here: (input field)" in the user's preferred
language.</p>
</dd>
<dt>A start tag whose tag name is "textarea"</dt>
<dd>
<ol>
<li><p><span>Insert an HTML element</span> for the
token.</p></li>
<li><p>If the next token is a U+000A LINE FEED (LF) character
token, then ignore that token and move on to the next
one. (Newlines at the start of <code>textarea</code> elements are
ignored as an authoring convenience.)</p></li>
<li><p>Switch the tokenizer to the <span>RCDATA
state</span>.</p></li>
<li><p>Let the <span>original insertion mode</span> be the
current <span>insertion mode</span>.</p>
<li><p>Set the <span>frameset-ok flag</span> to "not
ok".</p></li>
<li><p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: text">text</span>".</p></li>
</ol>
</dd>
<dt>A start tag whose tag name is "xmp"</dt>
<dd>
<p>If the <span>stack of open elements</span> <span title="has
an element in scope">has a <code>p</code> element in
scope</span>, then act as if an end tag with the tag name
"p" had been seen.</p>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
<p>Follow the <span>generic raw text element parsing algorithm</span>.</p>
</dd>
<dt>A start tag whose tag name is "iframe"</dt>
<dd>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
<p>Follow the <span>generic raw text element parsing algorithm</span>.</p>
</dd>
<dt>A start tag whose tag name is "noembed"</dt>
<dt>A start tag whose tag name is "noscript", if the <span>scripting flag</span> is enabled</dt>
<dd>
<p>Follow the <span>generic raw text element parsing algorithm</span>.</p>
</dd>
<dt>A start tag whose tag name is "select"</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
<p>If the <span>insertion mode</span> is one of <span
title="insertion mode: in table">in table</span>", "<span
title="insertion mode: in caption">in caption</span>", "<span
title="insertion mode: in column group">in column group</span>",
"<span title="insertion mode: in table body">in table
body</span>", "<span title="insertion mode: in row">in
row</span>", or "<span title="insertion mode: in cell">in
cell</span>", then switch the <span>insertion mode</span> to
"<span title="insertion mode: in select in table">in select in
table</span>". Otherwise, switch the <span>insertion mode</span>
to "<span title="insertion mode: in select">in select</span>".</p>
</dd>
<dt>A start tag whose tag name is one of: "optgroup", "option"</dt>
<dd>
<p>If the <span>stack of open elements</span> <span title="has an
element in scope">has an <code>option</code> element in
scope</span>, then act as if an end tag with the tag name "option"
had been seen.</p>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token.</p>
</dd>
<dt>A start tag whose tag name is one of: "rp", "rt"</dt>
<dd>
<!-- the parsing rules for ruby really don't match IE much at all,
but in practice the markup used is very simple and so strict
compatibility with IE isn't required. For example, as defined
here we get very, very different behaviour than IE for
pathological cases like:
<ruby><ol><li><p>a<rt>b
<ruby>a<rt>b<p>c
But in practice most ruby markup falls into these cases:
<ruby>a<rt>b</ruby>
<ruby>a<rp>b<rt>c<rp>d</ruby>
<ruby>a<rt>b</rt></ruby>
<ruby>a<rp>b</rp><rt>c</rt><rp>d</rp></ruby>
-->
<p>If the <span>stack of open elements</span> <span title="has an
element in scope">has a <code>ruby</code> element in scope</span>,
then <span>generate implied end tags</span>. If the <span>current
node</span> is not then a <code>ruby</code> element, this is a
<span>parse error</span>; pop all the nodes from the <span>current
node</span> up to the node immediately before the bottommost
<code>ruby</code> element on the <span>stack of open
elements</span>.</p>
<p><span>Insert an HTML element</span> for the token.</p>
</dd>
<dt>An end tag whose tag name is "br"</dt>
<dd>
<p><span>Parse error</span>. Act as if a start tag token with
the tag name "br" had been seen. Ignore the end tag token.</p>
</dd>
<dt>A start tag whose tag name is "math"</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Adjust MathML attributes</span> for the token. (This
fixes the case of MathML attributes that are not all
lowercase.)</p>
<p><span>Adjust foreign attributes</span> for the token. (This
fixes the use of namespaced attributes, in particular XLink.)</p>
<p><span>Insert a foreign element</span> for the token, in the
<span>MathML namespace</span>.</p>
<!-- If we ever change the frameset-ok flag to an insertion mode,
the following change would be implied, except we'd have to do it
even in the face of a self-closed tag:
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
-->
<p>If the token has its <i>self-closing flag</i> set, pop the
<span>current node</span> off the <span>stack of open
elements</span> and <span title="acknowledge self-closing
flag">acknowledge the token's <i>self-closing flag</i></span>.</p>
<p>Otherwise, if the <span>insertion mode</span> is not already
"<span title="insertion mode: in foreign content">in foreign
content</span>", let the <span>secondary insertion mode</span> be
the current <span>insertion mode</span>, and then switch the
<span>insertion mode</span> to "<span title="insertion mode: in
foreign content">in foreign content</span>".</p>
</dd>
<dt>A start tag whose tag name is "svg"</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Adjust SVG attributes</span> for the token. (This fixes
the case of SVG attributes that are not all lowercase.)</p>
<p><span>Adjust foreign attributes</span> for the token. (This
fixes the use of namespaced attributes, in particular XLink in
SVG.)</p>
<p><span>Insert a foreign element</span> for the token, in the
<span>SVG namespace</span>.</p>
<!-- If we ever change the frameset-ok flag to an insertion mode,
the following change would be implied, except we'd have to do it
even in the face of a self-closed tag:
<p>Set the <span>frameset-ok flag</span> to "not ok".</p>
-->
<p>If the token has its <i>self-closing flag</i> set, pop the
<span>current node</span> off the <span>stack of open
elements</span> and <span title="acknowledge self-closing
flag">acknowledge the token's <i>self-closing flag</i></span>.</p>
<p>Otherwise, if the <span>insertion mode</span> is not already
"<span title="insertion mode: in foreign content">in foreign
content</span>", let the <span>secondary insertion mode</span> be
the current <span>insertion mode</span>, and then switch the
<span>insertion mode</span> to "<span title="insertion mode: in
foreign content">in foreign content</span>".</p>
</dd>
<dt>A start <!--or end--> tag whose tag name is one of: "caption",
"col", "colgroup", "frame", "head", "tbody", "td", "tfoot", "th",
"thead", "tr"</dt>
<!--<dt>An end tag whose tag name is one of: "area", "base",
"basefont", "bgsound", "command", "embed", "hr", "iframe", "image",
"img", "input", "isindex", "keygen", "link", "meta", "noembed",
"noframes", "param", "script", "select", "source", "style",
"table", "textarea", "title", "wbr"</dt>-->
<!--<dt>An end tag whose tag name is "noscript", if the
<span>scripting flag</span> is enabled</dt>-->
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
<!-- end tags are commented out because since they can never end
up on the stack anyway, the default end tag clause will
automatically handle them. we don't want to have text in the spec
that is just an optimisation, as that detracts from the spec
itself -->
</dd>
<dt>Any other start tag</dt>
<dd>
<p><span>Reconstruct the active formatting elements</span>, if
any.</p>
<p><span>Insert an HTML element</span> for the token.</p>
<p class="note">This element will be a <span>phrasing</span>
element.</p>
</dd>
<dt>Any other end tag</dt>
<dd>
<p>Run the following steps:</p>
<ol>
<li><p>Initialize <var title="">node</var> to be the <span>current
node</span> (the bottommost node of the stack).</p></li>
<li><p>If <var title="">node</var> has the same tag name as
the end tag token, then:</p>
<ol>
<li><p><span>Generate implied end tags</span>.</p></li>
<li><p>If the tag name of the end tag token does not match
the tag name of the <span>current node</span>, this is a
<span>parse error</span>.</p></li>
<li><p>Pop all the nodes from the <span>current node</span> up
to <var title="">node</var>, including <var
title="">node</var>, then stop these steps.</p></li>
</ol>
</li>
<li><p>Otherwise, if <var title="">node</var> is in neither the
<span>formatting</span> category nor the <span>phrasing</span>
category, then this is a <span>parse error</span>; ignore the
token, and abort these steps.</p></li>
<li><p>Set <var title="">node</var> to the previous entry in the
<span>stack of open elements</span>.</p></li>
<li><p>Return to step 2.</p></li>
</ol>
</dd>
</dl>
<h5 id="parsing-main-incdata">The "<dfn title="insertion mode: text">text</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: text">text</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token</dt>
<dd>
<p><span title="insert a character">Insert the token's
character</span> into the <span>current node</span>.</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<!-- can't be the fragment case -->
<p><span>Parse error</span>.</p>
<p>If the <span>current node</span> is a <code>script</code>
element, mark the <code>script</code> element as <span>"already
started"</span>.</p>
<p>Pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p>Switch the <span>insertion mode</span> to the <span>original
insertion mode</span> and reprocess the current token.</p>
</dd>
<dt>An end tag whose tag name is "script"</dt>
<dd>
<p>Let <var title="">script</var> be the <span>current node</span>
(which will be a <code>script</code> element).</p>
<p>Pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p>Switch the <span>insertion mode</span> to the <span>original
insertion mode</span>.</p>
<p>Let the <var title="">old insertion point</var> have the
same value as the current <span>insertion point</span>. Let
the <span>insertion point</span> be just before the <span>next
input character</span>.</p>
<p>Increment the parser's <span>script nesting level</span> by
one.</p>
<p><span title="running a script">Run</span> the <var
title="">script</var>. This might cause some script to execute,
which might cause <span title="dom-document-write">new characters
to be inserted into the tokenizer</span>, and might cause the
tokenizer to output more tokens, resulting in a <a
href="#nestedParsing">reentrant invocation of the parser</a>.</p>
<p>Decrement the parser's <span>script nesting level</span> by
one. If the parser's <span>script nesting level</span> is zero,
then set the <span>parser pause flag</span> to false.</p>
<p>Let the <span>insertion point</span> have the value of the <var
title="">old insertion point</var>. (In other words, restore the
<span>insertion point</span> to its previous value. This value
might be the "undefined" value.)</p>
<p id="scriptTagParserResumes">At this stage, if there is a
<span>pending parsing-blocking script</span>, then:</p>
<dl class="switch">
<dt>If the <span>script nesting level</span> is not zero:</dt>
<dd>
<p>Set the <span>parser pause flag</span> to true, and abort the
processing of any nested invocations of the tokenizer, yielding
control back to the caller. (Tokenization will resume when the
caller returns to the "outer" tree construction stage.)</p>
<p class="note">The tree construction stage of this particular
parser is <a href="#nestedParsing">being called reentrantly</a>,
say from a call to <code
title="dom-document-write">document.write()</code>.</p>
</dd>
<dt>Otherwise:</dt>
<dd>
<p>Follow these steps:</p>
<ol>
<li><p>Let <var title="">the script</var> be the <span>pending
parsing-blocking script</span>. There is no longer a <span>pending
parsing-blocking script</span>.</p></li>
<li><p>Block the <span title="tokenization">tokenizer</span>
for this instance of the <span>HTML parser</span>, such that
the <span>event loop</span> will not run <span
title="concept-task">tasks</span> that invoke the <span
title="tokenization">tokenizer</span>.</p></li>
<li><p><span>Spin the event loop</span> until there is no <span
title="a style sheet blocking scripts">style sheet blocking
scripts</span> and <var title="">the script</var>'s
<span>"ready to be parser-executed"</span> flag is set.</p></li>
<li><p>Unblock the <span title="tokenization">tokenizer</span>
for this instance of the <span>HTML parser</span>, such that
<span title="concept-task">tasks</span> that invoke the <span
title="tokenization">tokenizer</span> can again be
run.</p></li>
<li><p>Let the <span>insertion point</span> be just before the
<span>next input character</span>.</p></li>
<li><p>Increment the parser's <span>script nesting level</span>
by one (it should be zero before this step, so this sets it to
one).</p></li>
<li><p><span title="executing a script block">Execute</span>
<var title="">the script</var>.</p></li>
<li><p>Decrement the parser's <span>script nesting level</span>
by one. If the parser's <span>script nesting level</span> is
zero (which it always should be at this point), then set the
<span>parser pause flag</span> to false.</p>
<li><p>Let the <span>insertion point</span> be undefined
again.</p></li>
<li><p>If there is once again a <span>pending parsing-blocking
script</span>, then repeat these steps from step 1.</p></li>
</ol>
</dd>
</dl>
</dd>
<dt>Any other end tag</dt>
<dd>
<p>Pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p>Switch the <span>insertion mode</span> to the <span>original
insertion mode</span>.</p>
</dd>
</dl>
<h5 id="parsing-main-intable">The "<dfn title="insertion mode: in table">in table</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in table">in table</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token</dt>
<dd>
<p>Let the <dfn><var>pending table character tokens</var></dfn>
be an empty list of tokens.</p>
<p>Let the <span>original insertion mode</span> be the current
<span>insertion mode</span>.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in table text">in table text</span>" and
reprocess the token.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "caption"</dt>
<dd>
<p><span>Clear the stack back to a table context</span>. (See
below.)</p>
<p>Insert a marker at the end of the <span>list of active
formatting elements</span>.</p>
<p><span>Insert an HTML element</span> for the token, then
switch the <span>insertion mode</span> to "<span
title="insertion mode: in caption">in caption</span>".</p>
</dd>
<dt>A start tag whose tag name is "colgroup"</dt>
<dd>
<p><span>Clear the stack back to a table context</span>. (See
below.)</p>
<p><span>Insert an HTML element</span> for the token, then
switch the <span>insertion mode</span> to "<span
title="insertion mode: in column group">in column
group</span>".</p>
</dd>
<dt>A start tag whose tag name is "col"</dt>
<dd>
<p>Act as if a start tag token with the tag name "colgroup"
had been seen, then reprocess the current token.</p>
</dd>
<dt>A start tag whose tag name is one of: "tbody", "tfoot", "thead"</dt>
<dd>
<p><span>Clear the stack back to a table context</span>. (See
below.)</p>
<p><span>Insert an HTML element</span> for the token, then
switch the <span>insertion mode</span> to "<span
title="insertion mode: in table body">in table
body</span>".</p>
</dd>
<dt>A start tag whose tag name is one of: "td", "th", "tr"</dt>
<dd>
<p>Act as if a start tag token with the tag name "tbody" had
been seen, then reprocess the current token.</p>
</dd>
<dt>A start tag whose tag name is "table"</dt>
<dd>
<p><span>Parse error</span>. Act as if an end tag token with
the tag name "table" had been seen, then, if that token wasn't
ignored, reprocess the current token.</p>
<p class="note">The fake end tag token here can only be
ignored in the <span>fragment case</span>.</p>
</dd>
<dt>An end tag whose tag name is "table"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have an element in table
scope</span> with the same tag name as the token, this is a
<span>parse error</span>. Ignore the token. (<span>fragment
case</span>)</p>
<p>Otherwise:</p>
<p>Pop elements from this stack until a <code>table</code>
element has been popped from the stack.</p>
<p><span>Reset the insertion mode appropriately</span>.</p>
</dd>
<dt>An end tag whose tag name is one of: "body", "caption",
"col", "colgroup", "html", "tbody", "td", "tfoot", "th",
"thead", "tr"</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is one of: "style", "script"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in head">in head</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A start tag whose tag name is "input"</dt>
<dd>
<p>If the token does not have an attribute with the name "type",
or if it does, but that attribute's value is not an <span>ASCII
case-insensitive</span> match for the string "<code
title="">hidden</code>", then: act as described in the "anything
else" entry below.</p>
<p>Otherwise:</p>
<p><span>Parse error</span>.</p>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Pop that <code>input</code> element off the <span>stack of
open elements</span>.</p>
</dd>
<dt>A start tag whose tag name is "form"</dt>
<dd>
<p><span>Parse error</span>.</p>
<p><span>Insert an HTML element</span> for the token.</p>
<p>Pop that <code>form</code> element off the <span>stack of
open elements</span>.</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p>If the <span>current node</span> is not the root
<code>html</code> element, then this is a <span>parse
error</span>.</p>
<p class="note">It can only be the <span>current node</span> in
the <span>fragment case</span>.</p>
<p><span>Stop parsing</span>.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p><span>Parse error</span>. Process the token <span>using the
rules for</span> the "<span title="insertion mode: in body">in
body</span>" <span>insertion mode</span>, except that if the
<span>current node</span> is a <code>table</code>,
<code>tbody</code>, <code>tfoot</code>, <code>thead</code>, or
<code>tr</code> element, then, whenever a node would be inserted
into the <span>current node</span>, it must instead be <span
title="foster parent">foster parented</span>.</p>
</dd>
</dl>
<p>When the steps above require the UA to <dfn>clear the stack
back to a table context</dfn>, it means that the UA must, while
the <span>current node</span> is not a <code>table</code>
element or an <code>html</code> element, pop elements from the
<span>stack of open elements</span>.</p>
<p class="note">The <span>current node</span> being an
<code>html</code> element after this process is a <span>fragment
case</span>.</p>
<h5 id="parsing-main-intabletext">The "<dfn title="insertion mode: in table text">in table text</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in table text">in table text</span>", tokens must be handled
as follows:</p>
<dl class="switch">
<dt>A character token</dt>
<dd>
<p>Append the character token to the <var>pending table character
tokens</var> list.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>If any of the tokens in the <var>pending table character
tokens</var> list are character tokens that are not one of U+0009
CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED
(FF), <!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE, then
reprocess those character tokens using the rules given in the
"anything else" entry in the <span title="insertion mode: in
table">in table</span>" insertion mode.</p>
<p>Otherwise, <span title="insert a character">insert the
characters</span> given by the <var>pending table character
tokens</var> list into the <span>current node</span>.</p>
<p>Switch the <span>insertion mode</span> to the <span>original
insertion mode</span> and reprocess the token.</p>
</dd>
</dl>
<h5 id="parsing-main-incaption">The "<dfn title="insertion mode: in caption">in caption</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in caption">in caption</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>An end tag whose tag name is "caption"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have an element in table
scope</span> with the same tag name as the token, this is a
<span>parse error</span>. Ignore the token. (<span>fragment
case</span>)</p>
<p>Otherwise:</p>
<p><span>Generate implied end tags</span>.</p>
<p>Now, if the <span>current node</span> is not a
<code>caption</code> element, then this is a <span>parse
error</span>.</p>
<p>Pop elements from this stack until a <code>caption</code>
element has been popped from the stack.</p>
<p><span>Clear the list of active formatting elements up to
the last marker</span>.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in table">in table</span>".</p>
</dd>
<dt>A start tag whose tag name is one of: "caption", "col",
"colgroup", "tbody", "td", "tfoot", "th", "thead", "tr"</dt>
<dt>An end tag whose tag name is "table"</dt>
<dd>
<p><span>Parse error</span>. Act as if an end tag with the tag
name "caption" had been seen, then, if that token wasn't
ignored, reprocess the current token.</p>
<p class="note">The fake end tag token here can only be
ignored in the <span>fragment case</span>.</p>
</dd>
<dt>An end tag whose tag name is one of: "body", "col",
"colgroup", "html", "tbody", "td", "tfoot", "th", "thead",
"tr"</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
</dl>
<h5 id="parsing-main-incolgroup">The "<dfn title="insertion mode: in column group">in column group</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in column group">in column group</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p><span title="insert a character">Insert the character</span> into
the <span>current node</span>.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A start tag whose tag name is "col"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token. Immediately
pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p><span title="acknowledge self-closing flag">Acknowledge the
token's <i>self-closing flag</i></span>, if it is set.</p>
</dd>
<dt>An end tag whose tag name is "colgroup"</dt>
<dd>
<p>If the <span>current node</span> is the root
<code>html</code> element, then this is a <span>parse
error</span>; ignore the token. (<span>fragment
case</span>)</p>
<p>Otherwise, pop the <span>current node</span> (which will be
a <code>colgroup</code> element) from the <span>stack of open
elements</span>. Switch the <span>insertion mode</span> to
"<span title="insertion mode: in table">in table</span>".</p>
</dd>
<dt>An end tag whose tag name is "col"</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p>If the <span>current node</span> is the root <code>html</code>
element, then <span>stop parsing</span>. (<span>fragment
case</span>)</p>
<p>Otherwise, act as described in the "anything else" entry
below.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Act as if an end tag with the tag name "colgroup" had been
seen, and then, if that token wasn't ignored, reprocess the
current token.</p>
<p class="note">The fake end tag token here can only be
ignored in the <span>fragment case</span>.</p>
</dd>
</dl>
<h5 id="parsing-main-intbody">The "<dfn title="insertion mode: in table body">in table body</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in table body">in table body</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A start tag whose tag name is "tr"</dt>
<dd>
<p><span>Clear the stack back to a table body
context</span>. (See below.)</p>
<p><span>Insert an HTML element</span> for the token, then switch
the <span>insertion mode</span> to "<span title="insertion mode:
in row">in row</span>".</p>
</dd>
<dt>A start tag whose tag name is one of: "th", "td"</dt>
<dd>
<p><span>Parse error</span>. Act as if a start tag with
the tag name "tr" had been seen, then reprocess the current
token.</p>
</dd>
<dt>An end tag whose tag name is one of: "tbody", "tfoot",
"thead"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have an element in table
scope</span> with the same tag name as the token, this is a
<span>parse error</span>. Ignore the token.</p>
<p>Otherwise:</p>
<p><span>Clear the stack back to a table body
context</span>. (See below.)</p>
<p>Pop the <span>current node</span> from the <span>stack of
open elements</span>. Switch the <span>insertion mode</span>
to "<span title="insertion mode: in table">in table</span>".</p>
</dd>
<dt>A start tag whose tag name is one of: "caption", "col",
"colgroup", "tbody", "tfoot", "thead"</dt>
<dt>An end tag whose tag name is "table"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have a
<code>tbody</code>, <code>thead</code>, or <code>tfoot</code>
element in table scope</span>, this is a <span>parse
error</span>. Ignore the token. (<span>fragment
case</span>)</p>
<p>Otherwise:</p>
<p><span>Clear the stack back to a table body
context</span>. (See below.)</p>
<p>Act as if an end tag with the same tag name as the
<span>current node</span> ("tbody", "tfoot", or "thead") had
been seen, then reprocess the current token.</p>
</dd>
<dt>An end tag whose tag name is one of: "body", "caption",
"col", "colgroup", "html", "td", "th", "tr"</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in table">in table</span>" <span>insertion
mode</span>.</p>
</dd>
</dl>
<p>When the steps above require the UA to <dfn>clear the stack
back to a table body context</dfn>, it means that the UA must,
while the <span>current node</span> is not a <code>tbody</code>,
<code>tfoot</code>, <code>thead</code>, or <code>html</code>
element, pop elements from the <span>stack of open
elements</span>.</p>
<p class="note">The <span>current node</span> being an
<code>html</code> element after this process is a <span>fragment
case</span>.</p>
<h5 id="parsing-main-intr">The "<dfn title="insertion mode: in row">in row</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in row">in row</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A start tag whose tag name is one of: "th", "td"</dt>
<dd>
<p><span>Clear the stack back to a table row
context</span>. (See below.)</p>
<p><span>Insert an HTML element</span> for the token, then switch
the <span>insertion mode</span> to "<span title="insertion mode:
in cell">in cell</span>".</p>
<p>Insert a marker at the end of the <span>list of active
formatting elements</span>.</p>
</dd>
<dt>An end tag whose tag name is "tr"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have an element in table
scope</span> with the same tag name as the token, this is a
<span>parse error</span>. Ignore the token. (<span>fragment
case</span>)</p>
<p>Otherwise:</p>
<p><span>Clear the stack back to a table row
context</span>. (See below.)</p>
<p>Pop the <span>current node</span> (which will be a
<code>tr</code> element) from the <span>stack of open
elements</span>. Switch the <span>insertion mode</span> to
"<span title="insertion mode: in table body">in table
body</span>".</p>
</dd>
<dt>A start tag whose tag name is one of: "caption", "col",
"colgroup", "tbody", "tfoot", "thead", "tr"</dt>
<dt>An end tag whose tag name is "table"</dt>
<dd>
<p>Act as if an end tag with the tag name "tr" had been seen,
then, if that token wasn't ignored, reprocess the current
token.</p>
<p class="note">The fake end tag token here can only be
ignored in the <span>fragment case</span>.</p>
</dd>
<dt>An end tag whose tag name is one of: "tbody", "tfoot",
"thead"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have an element in table
scope</span> with the same tag name as the token, this is a
<span>parse error</span>. Ignore the token.</p>
<p>Otherwise, act as if an end tag with the tag name "tr" had
been seen, then reprocess the current token.</p>
</dd>
<dt>An end tag whose tag name is one of: "body", "caption",
"col", "colgroup", "html", "td", "th"</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in table">in table</span>" <span>insertion
mode</span>.</p>
</dd>
</dl>
<p>When the steps above require the UA to <dfn>clear the stack
back to a table row context</dfn>, it means that the UA must,
while the <span>current node</span> is not a <code>tr</code>
element or an <code>html</code> element, pop elements from the
<span>stack of open elements</span>.</p>
<p class="note">The <span>current node</span> being an
<code>html</code> element after this process is a <span>fragment
case</span>.</p>
<h5 id="parsing-main-intd">The "<dfn title="insertion mode: in cell">in cell</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in cell">in cell</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>An end tag whose tag name is one of: "td", "th"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have an element in table
scope</span> with the same tag name as that of the token, then
this is a <span>parse error</span> and the token must be
ignored.</p>
<p>Otherwise:</p>
<p><span>Generate implied end tags</span>.</p>
<p>Now, if the <span>current node</span> is not an element
with the same tag name as the token, then this is a
<span>parse error</span>.</p>
<p>Pop elements from this stack until an element with the same
tag name as the token has been popped from the stack.</p>
<p><span>Clear the list of active formatting elements up to
the last marker</span>.</p>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: in row">in row</span>". (The
<span>current node</span> will be a <code>tr</code> element at
this point.)</p>
</dd>
<dt>A start tag whose tag name is one of: "caption", "col",
"colgroup", "tbody", "td", "tfoot", "th", "thead", "tr"</dt>
<dd>
<p>If the <span>stack of open elements</span> does
<em>not</em> <span title="has an element in table scope">have
a <code>td</code> or <code>th</code> element in table
scope</span>, then this is a <span>parse error</span>; ignore
the token. (<span>fragment case</span>)</p>
<p>Otherwise, <span>close the cell</span> (see below) and
reprocess the current token.</p>
</dd>
<dt>An end tag whose tag name is one of: "body", "caption",
"col", "colgroup", "html"</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>An end tag whose tag name is one of: "table", "tbody",
"tfoot", "thead", "tr"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have an element in table
scope</span> with the same tag name as that of the token
(which can only happen for "tbody", "tfoot" and "thead", or,
in the <span>fragment case</span>), then this is a <span>parse
error</span> and the token must be ignored.</p>
<p>Otherwise, <span>close the cell</span> (see below) and
reprocess the current token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
</dl>
<p>Where the steps above say to <dfn>close the cell</dfn>, they
mean to run the following algorithm:</p>
<ol>
<li><p>If the <span>stack of open elements</span> <span
title="has an element in table scope">has a <code>td</code>
element in table scope</span>, then act as if an end tag token
with the tag name "td" had been seen.</p></li>
<li><p>Otherwise, the <span>stack of open elements</span> will
<span title="has an element in table scope">have a
<code>th</code> element in table scope</span>; act as if an end
tag token with the tag name "th" had been seen.</p></li>
</ol>
<p class="note">The <span>stack of open elements</span> cannot
have both a <code>td</code> and a <code>th</code> element <span
title="has an element in table scope">in table scope</span> at
the same time, nor can it have neither when the <span>insertion
mode</span> is "<span title="insertion mode: in cell">in
cell</span>".</p>
<h5 id="parsing-main-inselect">The "<dfn title="insertion mode: in select">in select</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in select">in select</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token</dt>
<dd>
<p><span title="insert a character">Insert the token's
character</span> into the <span>current node</span>.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A start tag whose tag name is "option"</dt>
<dd>
<p>If the <span>current node</span> is an <code>option</code>
element, act as if an end tag with the tag name "option" had
been seen.</p>
<p><span>Insert an HTML element</span> for the token.</p>
</dd>
<dt>A start tag whose tag name is "optgroup"</dt>
<dd>
<p>If the <span>current node</span> is an <code>option</code>
element, act as if an end tag with the tag name "option" had
been seen.</p>
<p>If the <span>current node</span> is an
<code>optgroup</code> element, act as if an end tag with the
tag name "optgroup" had been seen.</p>
<p><span>Insert an HTML element</span> for the token.</p>
</dd>
<dt>An end tag whose tag name is "optgroup"</dt>
<dd>
<p>First, if the <span>current node</span> is an
<code>option</code> element, and the node immediately before
it in the <span>stack of open elements</span> is an
<code>optgroup</code> element, then act as if an end tag with
the tag name "option" had been seen.</p>
<p>If the <span>current node</span> is an
<code>optgroup</code> element, then pop that node from the
<span>stack of open elements</span>. Otherwise, this is a
<span>parse error</span>; ignore the token.</p>
</dd>
<dt>An end tag whose tag name is "option"</dt>
<dd>
<p>If the <span>current node</span> is an <code>option</code>
element, then pop that node from the <span>stack of open
elements</span>. Otherwise, this is a <span>parse
error</span>; ignore the token.</p>
</dd>
<dt>An end tag whose tag name is "select"</dt>
<dd>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have an element in table
scope</span> with the same tag name as the token, this is a
<span>parse error</span>. Ignore the token. (<span>fragment
case</span>)</p>
<p>Otherwise:</p>
<p>Pop elements from the <span>stack of open elements</span>
until a <code>select</code> element has been popped from the
stack.</p>
<p><span>Reset the insertion mode appropriately</span>.</p>
</dd>
<dt>A start tag whose tag name is "select"</dt>
<dd>
<p><span>Parse error</span>. Act as if the token had been
an end tag with the tag name "select" instead.</p>
</dd>
<dt>A start tag whose tag name is one of: "input", "keygen", "textarea"</dt>
<dd>
<p><span>Parse error</span>.</p>
<p>If the <span>stack of open elements</span> does not <span
title="has an element in table scope">have a <code>select</code>
element in table scope</span>, ignore the token. (<span>fragment
case</span>)</p>
<p>Otherwise, act as if an end tag with the tag name "select" had
been seen, and reprocess the token.</p>
</dd>
<dt>A start tag token whose tag name is "script"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in head">in head</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p>If the <span>current node</span> is not the root
<code>html</code> element, then this is a <span>parse
error</span>.</p>
<p class="note">It can only be the <span>current node</span> in
the <span>fragment case</span>.</p>
<p><span>Stop parsing</span>.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
</dl>
<h5 id="parsing-main-inselectintable">The "<dfn title="insertion mode: in select in table">in select in table</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in select in table">in select in table</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A start tag whose tag name is one of: "caption", "table",
"tbody", "tfoot", "thead", "tr", "td", "th"</dt>
<dd>
<p><span>Parse error</span>. Act as if an end tag with the tag
name "select" had been seen, and reprocess the token.</p>
</dd>
<dt>An end tag whose tag name is one of: "caption", "table",
"tbody", "tfoot", "thead", "tr", "td", "th"</dt>
<dd>
<p><span>Parse error</span>.</p>
<p>If the <span>stack of open elements</span> <span>has an
element in table scope</span> with the same tag name as that
of the token, then act as if an end tag with the tag name
"select" had been seen, and reprocess the token. Otherwise,
ignore the token.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in select">in select</span>" <span>insertion
mode</span>.</p>
</dd>
</dl>
<h5 id="parsing-main-inforeign">The "<dfn title="insertion mode: in foreign content">in foreign content</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in foreign content">in foreign content</span>", tokens must be
handled as follows:</p>
<dl class="switch">
<dt>A character token</dt>
<dd>
<p><span title="insert a character">Insert the token's
character</span> into the <span>current node</span>.</p>
<p>If the token is not one of U+0009 CHARACTER TABULATION, U+000A
LINE FEED (LF), U+000C FORM FEED (FF), <!--U+000D CARRIAGE RETURN
(CR),--> or U+0020 SPACE, then set the <span>frameset-ok
flag</span> to "not ok".</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>An end tag whose tag name is "script", if the <span>current node</span> is a <code title="">script</code> element in the <span>SVG namespace</span>.</dt>
<dd>
<p>Pop the <span>current node</span> off the <span>stack of open
elements</span>.</p>
<p>Let the <var title="">old insertion point</var> have the
same value as the current <span>insertion point</span>. Let
the <span>insertion point</span> be just before the <span>next
input character</span>.</p>
<p>Increment the parser's <span>script nesting level</span> by
one. Set the <span>parser pause flag</span> to true.</p>
<p><a
href="http://www.w3.org/TR/SVGMobile12/script.html#ScriptContentProcessing">Process
the <code title="">script</code> element</a> according to the SVG
rules, if the user agent supports SVG. <a
href="#refsSVG">[SVG]</a></p>
<p class="note">Even if this causes <span
title="dom-document-write">new characters to be inserted into the
tokenizer</span>, the parser will not be executed reentrantly,
since the <span>parser pause flag</span> is true.</p>
<p>Decrement the parser's <span>script nesting level</span> by
one. If the parser's <span>script nesting level</span> is zero,
then set the <span>parser pause flag</span> to false.</p>
<p>Let the <span>insertion point</span> have the value of the <var
title="">old insertion point</var>. (In other words, restore the
<span>insertion point</span> to its previous value. This value
might be the "undefined" value.)</p>
</dd>
<dt>A start tag whose tag name is neither "mglyph" nor "malignmark", if the <span>current node</span> is an <code title="">mi</code> element in the <span>MathML namespace</span>.</dt>
<dt>A start tag whose tag name is neither "mglyph" nor "malignmark", if the <span>current node</span> is an <code title="">mo</code> element in the <span>MathML namespace</span>.</dt>
<dt>A start tag whose tag name is neither "mglyph" nor "malignmark", if the <span>current node</span> is an <code title="">mn</code> element in the <span>MathML namespace</span>.</dt>
<dt>A start tag whose tag name is neither "mglyph" nor "malignmark", if the <span>current node</span> is an <code title="">ms</code> element in the <span>MathML namespace</span>.</dt>
<dt>A start tag whose tag name is neither "mglyph" nor "malignmark", if the <span>current node</span> is an <code title="">mtext</code> element in the <span>MathML namespace</span>.</dt>
<dt>A start tag whose tag name is "svg", if the <span>current node</span> is an <code title="">annotation-xml</code> element in the <span>MathML namespace</span>.</dt>
<dt>A start tag, if the <span>current node</span> is a <code title="">foreignObject</code> element in the <span>SVG namespace</span>.</dt>
<dt>A start tag, if the <span>current node</span> is a <code title="">desc</code> element in the <span>SVG namespace</span>.</dt>
<dt>A start tag, if the <span>current node</span> is a <code title="">title</code> element in the <span>SVG namespace</span>.</dt>
<dt>A start tag, if the <span>current node</span> is an element in the <span>HTML namespace</span>.</dt>
<dt>An end tag</dt>
<dd>
<p>Process the token <span>using the rules for</span> the
<span>secondary insertion mode</span>.</p>
<p>If, after doing so, the <span>insertion mode</span> is still
"<span title="insertion mode: in foreign content">in foreign
content</span>", but there is no element <span title="has an
element in scope">in scope</span> that has a namespace other than
the <span>HTML namespace</span>, switch the <span>insertion
mode</span> to the <span>secondary insertion mode</span>.</p>
</dd>
<dt>A start tag whose tag name is one of: <!--"a",--> "b", "big",
"blockquote", "body"<!--by inspection-->, "br", "center", "code",
"dd", "div", "dl", "dt"<!-- so that dd and dt can be handled
uniformly throughout the parser -->, "em", "embed", "h1", "h2",
"h3", "h4"<!--for completeness-->, "h5", "h6"<!--for
completeness-->, "head"<!--by inspection-->, "hr", "i", "img",
"li", "listing"<!-- so that pre and listing can be handled
uniformly throughout the parser -->, "menu", "meta", "nobr",
"ol"<!-- so that dl, ul, and ol can be handled uniformly throughout
the parser -->, "p", "pre", "ruby", "s", <!--"script",--> "small",
"span", "strong", "strike"<!-- so that s and strike can be handled
uniformly throughout the parser -->, <!--"style",--> "sub", "sup",
"table"<!--by inspection-->, "tt", "u", "ul", "var"</dt> <!-- this
list was determined empirically by studying over 6,000,000,000
pages that were specifically not XML pages -->
<dt>A start tag whose tag name is "font", if the token has any
attributes named "color", "face", or "size"</dt> <!-- the
attributes here are required so that SVG <font> will go through as
SVG but legacy <font>s won't -->
<dt>An end-of-file token</dt> <dd>
<p><span>Parse error</span>.</p>
<p>Pop elements from the <span>stack of open elements</span> until
the <span>current node</span> is in the <span>HTML
namespace</span>.</p>
<p>Switch the <span>insertion mode</span> to the <span>secondary
insertion mode</span>, and reprocess the token.</p>
</dd>
<dt>Any other start tag</dt>
<dd>
<p>If the <span>current node</span> is an element in the
<span>MathML namespace</span>, <span>adjust MathML
attributes</span> for the token. (This fixes the case of MathML
attributes that are not all lowercase.)</p>
<p>If the <span>current node</span> is an element in the <span>SVG
namespace</span>, and the token's tag name is one of the ones in
the first column of the following table, change the tag name to
the name given in the corresponding cell in the second
column. (This fixes the case of SVG elements that are not all
lowercase.)</p>
<table>
<thead>
<tr> <th> Tag name <th> Element name
<tbody>
<tr> <td> <code title="">altglyph</code> <td> <code title="">altGlyph</code>
<tr> <td> <code title="">altglyphdef</code> <td> <code title="">altGlyphDef</code>
<tr> <td> <code title="">altglyphitem</code> <td> <code title="">altGlyphItem</code>
<tr> <td> <code title="">animatecolor</code> <td> <code title="">animateColor</code>
<tr> <td> <code title="">animatemotion</code> <td> <code title="">animateMotion</code>
<tr> <td> <code title="">animatetransform</code> <td> <code title="">animateTransform</code>
<tr> <td> <code title="">clippath</code> <td> <code title="">clipPath</code>
<tr> <td> <code title="">feblend</code> <td> <code title="">feBlend</code>
<tr> <td> <code title="">fecolormatrix</code> <td> <code title="">feColorMatrix</code>
<tr> <td> <code title="">fecomponenttransfer</code> <td> <code title="">feComponentTransfer</code>
<tr> <td> <code title="">fecomposite</code> <td> <code title="">feComposite</code>
<tr> <td> <code title="">feconvolvematrix</code> <td> <code title="">feConvolveMatrix</code>
<tr> <td> <code title="">fediffuselighting</code> <td> <code title="">feDiffuseLighting</code>
<tr> <td> <code title="">fedisplacementmap</code> <td> <code title="">feDisplacementMap</code>
<tr> <td> <code title="">fedistantlight</code> <td> <code title="">feDistantLight</code>
<tr> <td> <code title="">feflood</code> <td> <code title="">feFlood</code>
<tr> <td> <code title="">fefunca</code> <td> <code title="">feFuncA</code>
<tr> <td> <code title="">fefuncb</code> <td> <code title="">feFuncB</code>
<tr> <td> <code title="">fefuncg</code> <td> <code title="">feFuncG</code>
<tr> <td> <code title="">fefuncr</code> <td> <code title="">feFuncR</code>
<tr> <td> <code title="">fegaussianblur</code> <td> <code title="">feGaussianBlur</code>
<tr> <td> <code title="">feimage</code> <td> <code title="">feImage</code>
<tr> <td> <code title="">femerge</code> <td> <code title="">feMerge</code>
<tr> <td> <code title="">femergenode</code> <td> <code title="">feMergeNode</code>
<tr> <td> <code title="">femorphology</code> <td> <code title="">feMorphology</code>
<tr> <td> <code title="">feoffset</code> <td> <code title="">feOffset</code>
<tr> <td> <code title="">fepointlight</code> <td> <code title="">fePointLight</code>
<tr> <td> <code title="">fespecularlighting</code> <td> <code title="">feSpecularLighting</code>
<tr> <td> <code title="">fespotlight</code> <td> <code title="">feSpotLight</code>
<tr> <td> <code title="">fetile</code> <td> <code title="">feTile</code>
<tr> <td> <code title="">feturbulence</code> <td> <code title="">feTurbulence</code>
<tr> <td> <code title="">foreignobject</code> <td> <code title="">foreignObject</code>
<tr> <td> <code title="">glyphref</code> <td> <code title="">glyphRef</code>
<tr> <td> <code title="">lineargradient</code> <td> <code title="">linearGradient</code>
<tr> <td> <code title="">radialgradient</code> <td> <code title="">radialGradient</code>
<!--<tr> <td> <code title="">solidcolor</code> <td> <code title="">solidColor</code> (SVG 1.2)-->
<tr> <td> <code title="">textpath</code> <td> <code title="">textPath</code>
</table>
<p>If the <span>current node</span> is an element in the <span>SVG
namespace</span>, <span>adjust SVG attributes</span> for the
token. (This fixes the case of SVG attributes that are not all
lowercase.)</p>
<p><span>Adjust foreign attributes</span> for the token. (This
fixes the use of namespaced attributes, in particular XLink in
SVG.)</p>
<p><span>Insert a foreign element</span> for the token, in the
same namespace as the <span>current node</span>.</p>
<p>If the token has its <i>self-closing flag</i> set, pop the
<span>current node</span> off the <span>stack of open
elements</span> and <span title="acknowledge self-closing
flag">acknowledge the token's <i>self-closing flag</i></span>.</p>
</dd>
</dl>
<h5 id="parsing-main-afterbody">The "<dfn title="insertion mode: after body">after body</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: after body">after body</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the first element in
the <span>stack of open elements</span> (the <code>html</code>
element), with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end tag whose tag name is "html"</dt>
<dd>
<p>If the parser was originally created as part of the <span>HTML
fragment parsing algorithm</span>, this is a <span>parse
error</span>; ignore the token. (<span>fragment case</span>)</p>
<p>Otherwise, switch the <span>insertion mode</span> to "<span
title="insertion mode: after after body">after after
body</span>".</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p><span>Stop parsing</span>.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p><span>Parse error</span>. Switch the <span>insertion
mode</span> to "<span title="insertion mode: in body">in
body</span>" and reprocess the token.</p>
</dd>
</dl>
<h5 id="parsing-main-inframeset">The "<dfn title="insertion mode: in frameset">in frameset</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: in frameset">in frameset</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p><span title="insert a character">Insert the character</span> into
the <span>current node</span>.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>A start tag whose tag name is "frameset"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token.</p>
</dd>
<dt>An end tag whose tag name is "frameset"</dt>
<dd>
<p>If the <span>current node</span> is the root
<code>html</code> element, then this is a <span>parse
error</span>; ignore the token. (<span>fragment
case</span>)</p>
<p>Otherwise, pop the <span>current node</span> from the
<span>stack of open elements</span>.</p>
<p>If the parser was <em>not</em> originally created as part
of the <span>HTML fragment parsing algorithm</span>
(<span>fragment case</span>), and the <span>current
node</span> is no longer a <code>frameset</code> element, then
switch the <span>insertion mode</span> to "<span
title="insertion mode: after frameset">after
frameset</span>".</p>
</dd>
<dt>A start tag whose tag name is "frame"</dt>
<dd>
<p><span>Insert an HTML element</span> for the token.
Immediately pop the <span>current node</span> off the
<span>stack of open elements</span>.</p>
<p><span title="acknowledge self-closing flag">Acknowledge the
token's <i>self-closing flag</i></span>, if it is set.</p>
</dd>
<dt>A start tag whose tag name is "noframes"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in head">in head</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p>If the <span>current node</span> is not the root
<code>html</code> element, then this is a <span>parse
error</span>.</p>
<p class="note">It can only be the <span>current node</span> in
the <span>fragment case</span>.</p>
<p><span>Stop parsing</span>.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
</dl>
<h5 id="parsing-main-afterframeset">The "<dfn title="insertion mode: after frameset">after frameset</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: after frameset">after frameset</span>", tokens must be handled as follows:</p>
<!-- due to rules in the "in frameset" mode, this can't be entered in the fragment case -->
<dl class="switch">
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dd>
<p><span title="insert a character">Insert the character</span> into
the <span>current node</span>.</p>
</dd>
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <span>current
node</span> with the <code title="">data</code> attribute set to
the data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end tag whose tag name is "html"</dt>
<dd>
<p>Switch the <span>insertion mode</span> to "<span
title="insertion mode: after after frameset">after after
frameset</span>".</p>
</dd>
<dt>A start tag whose tag name is "noframes"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in head">in head</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p><span>Stop parsing</span>.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
</dl>
<h5>The "<dfn title="insertion mode: after after body">after after body</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: after after body">after after body</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <code>Document</code>
object with the <code title="">data</code> attribute set to the
data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p><span>Stop parsing</span>.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p><span>Parse error</span>. Switch the <span>insertion mode</span>
to "<span title="insertion mode: in body">in body</span>" and
reprocess the token.</p>
</dd>
</dl>
<h5>The "<dfn title="insertion mode: after after frameset">after after frameset</dfn>" insertion mode</h5>
<p>When the <span>insertion mode</span> is "<span title="insertion
mode: after after frameset">after after frameset</span>", tokens must be handled as follows:</p>
<dl class="switch">
<dt>A comment token</dt>
<dd>
<p>Append a <code>Comment</code> node to the <code>Document</code>
object with the <code title="">data</code> attribute set to the
data given in the comment token.</p>
</dd>
<dt>A DOCTYPE token</dt>
<dt>A character token that is one of U+0009 CHARACTER
TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF),
<!--U+000D CARRIAGE RETURN (CR),--> or U+0020 SPACE</dt>
<dt>A start tag whose tag name is "html"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in body">in body</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>An end-of-file token</dt>
<dd>
<p><span>Stop parsing</span>.</p>
</dd>
<dt>A start tag whose tag name is "noframes"</dt>
<dd>
<p>Process the token <span>using the rules for</span> the "<span
title="insertion mode: in head">in head</span>" <span>insertion
mode</span>.</p>
</dd>
<dt>Anything else</dt>
<dd>
<p><span>Parse error</span>. Ignore the token.</p>
</dd>
</dl>
</div>
<div class="impl">
<h4>The end</h4>
<p>Once the user agent <dfn title="stop parsing">stops parsing</dfn>
the document, the user agent must run the following steps:</p>
<ol>
<!-- this happens as part of one of the tasks that runs the parser -->
<li><p>Set the <span>current document readiness</span> to
"interactive" <!-- this also synchronously fires an event --> and
the <span>insertion point</span> to undefined.</p></li>
<li><p>If the <span>list of scripts that will execute when the
document has finished parsing</span> is not empty, run these
substeps:</p>
<ol>
<li><p><span>Spin the event loop</span> until the first
<code>script</code> in the <span>list of scripts that will
execute when the document has finished parsing</span> has its
<span>"ready to be parser-executed"</span> flag set <em>and</em> there
is no <span title="a style sheet blocking scripts">style sheet
blocking scripts</span>.</p></li>
<li><p><span title="executing a script block">Execute</span> the
first <code>script</code> in the <span>list of scripts that will
execute when the document has finished parsing</span>.</p></li>
<li><p>Remove the first <code>script</code> element from the
<span>list of scripts that will execute when the document has
finished parsing</span> (i.e. shift out the first entry in the
list).</p></li>
<li><p>If the <span>list of scripts that will execute when the
document has finished parsing</span> is still not empty, repeat
these substeps again from substep 1.</p>
</ol>
</li>
<li><p><span>Spin the event loop</span> until the <span>list of
scripts that will execute as soon as possible</span> is
empty.</p></li>
<li><p><span>Queue a task</span> to <span>fire a simple
event</span> named <code
title="event-DOMContentLoaded">DOMContentLoaded</code> at the
<code>Document</code>.</p></li>
<li><p><span>Spin the event loop</span> until there is nothing that
<dfn title="delay the load event">delays the load event</dfn> in
the <code>Document</code>.</p></li>
<li><p><span>Queue a task</span> to set the <span>current document
readiness</span> to "complete". <!-- this also fires an event
synchronously during the task --></p></li>
<li><p>If the <code>Document</code> is in a <span>browsing
context</span>, then <span>queue a task</span> to <span>fire a
simple event</span> named <code title="event-load">load</code> at
the <code>Document</code>'s <code>Window</code> object, but with
its <code title="dom-event-target">target</code> set to the
<code>Document</code> object (and the <code
title="dom-event-currentTarget">currentTarget</code> set to the
<code>Window</code> object).</p></li>
<li><p>If the <code>Document</code> is in a <span>browsing
context</span>, then <span>queue a task</span> to <span>fire a
simple event</span> named <code
title="event-pageshow">pageshow</code> at the
<code>Document</code>'s <code>Window</code> object.</p></li>
<li><p>If the <code>Document</code> has a <span>pending state
object</span>, then <span>queue a task</span> to fire a <code
title="event-popstate">popstate</code> event at the
<code>Document</code>'s <code>Window</code> object using the
<code>PopStateEvent</code> interface, with the <code
title="dom-PopStateEvent-state">state</code> attribute set to the
current value of the <span>pending state object</span>. This event
must bubble but not be cancelable and has no default
action.</p></li>
</ol>
<p>The <span>task source</span> for the <span
title="concept-task">tasks</span> mentioned in this section is the
<span>DOM manipulation task source</span>.</p>
</div>
<div class="impl">
<h4>Coercing an HTML DOM into an infoset</h4>
<p>When an application uses an <span>HTML parser</span> in
conjunction with an XML pipeline, it is possible that the
constructed DOM is not compatible with the XML tool chain in certain
subtle ways. For example, an XML toolchain might not be able to
represent attributes with the name <code title="">xmlns</code>,
since they conflict with the Namespaces in XML syntax. There is also
some data that the <span>HTML parser</span> generates that isn't
included in the DOM itself. This section specifies some rules for
handling these issues.</p>
<p>If the XML API being used doesn't support DOCTYPEs, the tool may
drop DOCTYPEs altogether.</p>
<p>If the XML API doesn't support attributes in no namespace that
are named "<code title="">xmlns</code>", attributes whose names
start with "<code title="">xmlns:</code>", or attributes in the
<span>XMLNS namespace</span>, then the tool may drop such
attributes.</p>
<p>The tool may annotate the output with any namespace declarations
required for proper operation.</p>
<p>If the XML API being used restricts the allowable characters in
the local names of elements and attributes, then the tool may map
all element and attribute local names that the API wouldn't support
to a set of names that <em>are</em> allowed, by replacing any
character that isn't supported with the uppercase letter U and the
six digits of the character's Unicode code point when expressed in
hexadecimal, using digits 0-9 and capital letters A-F as the
symbols, in increasing numeric order.</p>
<p class="example">For example, the element name <code
title="">foo<bar</code>, which can be output by the <span>HTML
parser</span>, though it is neither a legal HTML element name nor a
well-formed XML element name, would be converted into <code
title="">fooU00003Cbar</code>, which <em>is</em> a well-formed XML
element name (though it's still not legal in HTML by any means).</p>
<p class="example">As another example, consider the attribute
<code>xlink:href</code>. Used on a MathML element, it becomes, after
being <span title="adjust foreign attributes">adjusted</span>, an
attribute with a prefix "<code title="">xlink</code>" and a local
name "<code title="">href</code>". However, used on an HTML element,
it becomes an attribute with no prefix and the local name "<code
title="">xlink:href</code>", which is not a valid NCName, and thus
might not be accepted by an XML API. It could thus get converted,
becoming "<code title="">xlinkU00003Ahref</code>".</p>
<p class="note">The resulting names from this conversion
conveniently can't clash with any attribute generated by the
<span>HTML parser</span>, since those are all either lowercase or
those listed in the <span>adjust foreign attributes</span>
algorithm's table.</p>
<p>If the XML API restricts comments from having two consecutive
U+002D HYPHEN-MINUS characters (--), the tool may insert a single
U+0020 SPACE character between any such offending characters.</p>
<p>If the XML API restricts comments from ending in a
U+002D HYPHEN-MINUS character (-), the tool may insert a single
U+0020 SPACE character at the end of such comments.</p>
<p>If the XML API restricts allowed characters in character data,
attribute values, or comments, the tool may replace any U+000C FORM
FEED (FF) character with a U+0020 SPACE character, and any other
literal non-XML character with a U+FFFD REPLACEMENT CHARACTER.</p>
<p>If the tool has no way to convey out-of-band information, then
the tool may drop the following information:</p>
<ul>
<li>Whether the document is set to <i>no quirks mode</i>,
<i>limited quirks mode</i>, or <i>quirks mode</i></li>
<li>The association between form controls and forms that aren't
their nearest <code>form</code> element ancestor (use of the
<span><code>form</code> element pointer</span> in the parser)</li>
</ul>
<p class="note">The mutations allowed by this section apply
<em>after</em> the <span>HTML parser</span>'s rules have been
applied. For example, a <code title=""><a::></code> start tag
will be closed by a <code title=""></a::></code> end tag, and
never by a <code title=""></aU00003AU00003A></code> end tag, even
if the user agent is using the rules above to then generate an
actual element in the DOM with the name <code
title="">aU00003AU00003A</code> for that start tag.</p>
</div>
<div class="impl">
<h4>An introduction to error handling and strange cases in the parser</h4>
<p><i>This section is non-normative.</i></p>
<p>This section examines some erroneous markup and discusses how
the <span>HTML parser</span> handles these cases.</p>
<h5>Misnested tags: <b><i></b></i></h5>
<p><i>This section is non-normative.</i></p>
<p>The most-often discussed example of erroneous markup is as
follows:</p>
<pre><p>1<b>2<i>3</b>4</i>5</p></pre>
<p>The parsing of this markup is straightforward up to the "3". At
this point, the DOM looks like this:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>p</code><ul><li class="t3"><code>#text</code>: <span title="">1</span></li><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">2</span></li><li class="t1"><code>i</code><ul><li class="t3"><code>#text</code>: <span title="">3</span></li></ul></li></ul></li></ul></li></ul></li></ul></li></ul>
<p>Here, the <span>stack of open elements</span> has five elements
on it: <code>html</code>, <code>body</code>, <code>p</code>,
<code>b</code>, and <code>i</code>. The <span>list of active
formatting elements</span> just has two: <code>b</code> and
<code>i</code>. The <span>insertion mode</span> is "<span
title="insertion mode: in body">in body</span>".</p>
<p>Upon receiving the end tag token with the tag name "b", the "<a
href="#adoptionAgency">adoption agency algorithm</a>" is
invoked. This is a simple case, in that the <var title="">formatting
element</var> is the <code>b</code> element, and there is no
<var title="">furthest block</var>. Thus, the <span>stack of open
elements</span> ends up with just three elements: <code>html</code>,
<code>body</code>, and <code>p</code>, while the <span>list of
active formatting elements</span> has just one: <code>i</code>. The
DOM tree is unmodified at this point.</p>
<p>The next token is a character ("4"), triggers the <span
title="reconstruct the active formatting elements">reconstruction of
the active formatting elements</span>, in this case just the
<code>i</code> element. A new <code>i</code> element is thus created
for the "4" text node. After the end tag token for the "i" is also
received, and the "5" text node is inserted, the DOM looks as
follows:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>p</code><ul><li class="t3"><code>#text</code>: <span title="">1</span></li><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">2</span></li><li class="t1"><code>i</code><ul><li class="t3"><code>#text</code>: <span title="">3</span></li></ul></li></ul></li><li class="t1"><code>i</code><ul><li class="t3"><code>#text</code>: <span title="">4</span></li></ul></li><li class="t3"><code>#text</code>: <span title="">5</span></li></ul></li></ul></li></ul></li></ul>
<h5>Misnested tags: <b><p></b></p></h5>
<p><i>This section is non-normative.</i></p>
<p>A case similar to the previous one is the following:</p>
<pre><b>1<p>2</b>3</p></pre>
<p>Up to the "2" the parsing here is straightforward:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">1</span></li><li class="t1"><code>p</code><ul><li class="t3"><code>#text</code>: <span title="">2</span></li></ul></li></ul></li></ul></li></ul></li></ul>
<p>The interesting part is when the end tag token with the tag name
"b" is parsed.</p>
<p>Before that token is seen, the <span>stack of open
elements</span> has four elements on it: <code>html</code>,
<code>body</code>, <code>b</code>, and <code>p</code>. The
<span>list of active formatting elements</span> just has the one:
<code>b</code>. The <span>insertion mode</span> is "<span
title="insertion mode: in body">in body</span>".</p>
<p>Upon receiving the end tag token with the tag name "b", the "<a
href="#adoptionAgency">adoption agency algorithm</a>" is invoked, as
in the previous example. However, in this case, there <em>is</em> a
<var title="">furthest block</var>, namely the <code>p</code> element. Thus,
this time the adoption agency algorithm isn't skipped over.</p>
<p>The <var title="">common ancestor</var> is the <code>body</code>
element. A conceptual "bookmark" marks the position of the
<code>b</code> in the <span>list of active formatting
elements</span>, but since that list has only one element in it,
it won't have much effect.</p>
<p>As the algorithm progresses, <var title="">node</var> ends up set
to the formatting element (<code>b</code>), and <var title="">last
node</var> ends up set to the <var title="">furthest block</var>
(<code>p</code>).</p>
<p>The <var title="">last node</var> gets appended (moved) to the
<var title="">common ancestor</var>, so that the DOM looks like:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">1</span></li></ul></li><li class="t1"><code>p</code><ul><li class="t3"><code>#text</code>: <span title="">2</span></li></ul></li></ul></li></ul></li></ul>
<p>A new <code>b</code> element is created, and the children of the
<code>p</code> element are moved to it:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">1</span></li></ul></li><li class="t1"><code>p</code></li></ul></li></ul></li></ul>
<ul class="domTree"><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">2</span></li></ul></li></ul>
<p>Finally, the new <code>b</code> element is appended to the
<code>p</code> element, so that the DOM looks like:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">1</span></li></ul></li><li class="t1"><code>p</code><ul><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">2</span></li></ul></li></ul></li></ul></li></ul></li></ul>
<p>The <code>b</code> element is removed from the <span>list of
active formatting elements</span> and the <span>stack of open
elements</span>, so that when the "3" is parsed, it is appended to
the <code>p</code> element:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">1</span></li></ul></li><li class="t1"><code>p</code><ul><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">2</span></li></ul></li><li class="t3"><code>#text</code>: <span title="">3</span></li></ul></li></ul></li></ul></li></ul>
<h5>Unexpected markup in tables</h5>
<p><i>This section is non-normative.</i></p>
<p>Error handling in tables is, for historical reasons, especially
strange. For example, consider the following markup:</p>
<pre><table><strong><b></strong><tr><td>aaa</td></tr><strong>bbb</strong></table>ccc</pre>
<p>The highlighted <code>b</code> element start tag is not allowed
directly inside a table like that, and the parser handles this case
by placing the element <em>before</em> the table. (This is called <i
title="foster parent">foster parenting</i>.) This can be seen by
examining the DOM tree as it stands just after the
<code>table</code> element's start tag has been seen:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>table</code></li></ul></li></ul></li></ul>
<p>...and then immediately after the <code>b</code> element start
tag has been seen:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code></li><li class="t1"><code>table</code></li></ul></li></ul></li></ul>
<p>At this point, the <span>stack of open elements</span> has on it
the elements <code>html</code>, <code>body</code>,
<code>table</code>, and <code>b</code> (in that order, despite the
resulting DOM tree); the <span>list of active formatting
elements</span> just has the <code>b</code> element in it; and the
<span>insertion mode</span> is "<span title="insertion mode: in
table">in table</span>".</p>
<p>The <code>tr</code> start tag causes the <code>b</code> element
to be popped off the stack and a <code>tbody</code> start tag to be
implied; the <code>tbody</code> and <code>tr</code> elements are
then handled in a rather straight-forward manner, taking the parser
through the "<span title="insertion mode: in table body">in table
body</span>" and "<span title="insertion mode: in row">in
row</span>" insertion modes, after which the DOM looks as
follows:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code></li><li class="t1"><code>table</code><ul><li class="t1"><code>tbody</code><ul><li class="t1"><code>tr</code></li></ul></li></ul></li></ul></li></ul></li></ul>
<p>Here, the <span>stack of open elements</span> has on it the
elements <code>html</code>, <code>body</code>, <code>table</code>,
<code>tbody</code>, and <code>tr</code>; the <span>list of active
formatting elements</span> still has the <code>b</code> element in
it; and the <span>insertion mode</span> is "<span title="insertion
mode: in row">in row</span>".</p>
<p>The <code>td</code> element start tag token, after putting a
<code>td</code> element on the tree, puts a marker on the <span>list
of active formatting elements</span> (it also switches to the "<span
title="insertion mode: in cell">in cell</span>" <span>insertion
mode</span>).</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code></li><li class="t1"><code>table</code><ul><li class="t1"><code>tbody</code><ul><li class="t1"><code>tr</code><ul><li class="t1"><code>td</code></li></ul></li></ul></li></ul></li></ul></li></ul></li></ul>
<p>The marker means that when the "aaa" character tokens are seen,
no <code>b</code> element is created to hold the resulting text
node:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code></li><li class="t1"><code>table</code><ul><li class="t1"><code>tbody</code><ul><li class="t1"><code>tr</code><ul><li class="t1"><code>td</code><ul><li class="t3"><code>#text</code>: <span title="">aaa</span></li></ul></li></ul></li></ul></li></ul></li></ul></li></ul></li></ul>
<p>The end tags are handled in a straight-forward manner; after
handling them, the <span>stack of open elements</span> has on it the
elements <code>html</code>, <code>body</code>, <code>table</code>,
and <code>tbody</code>; the <span>list of active formatting
elements</span> still has the <code>b</code> element in it (the
marker having been removed by the "td" end tag token); and the
<span>insertion mode</span> is "<span title="insertion mode: in
table body">in table body</span>".</p>
<p>Thus it is that the "bbb" character tokens are found. These
trigger the "<span title="insertion mode: in table text">in table
text</span>" insertion mode to be used (with the <span>original
insertion mode</span> set to "<span title="insertion mode: in table
body">in table body</span>"). The character tokens are collected,
and when the next token (the <code>table</code> element end tag) is
seen, they are processed as a group. Since they are not all spaces,
they are handled as per the "anything else" rules in the "<span
title="insertion mode: in table">in table</span>" insertion mode,
which defer to the "<span title="insertion mode: in body">in
body</span>" insertion mode but with <span title="foster
parent">foster parenting</span>.</p>
<p>When <span title="reconstruct the active formatting elements">the
active formatting elements are reconstructed</span>, a
<code>b</code> element is created and <span title="foster
parent">foster parented</span>, and then the "bbb" text node is
appended to it:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code></li><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">bbb</span></li></ul></li><li class="t1"><code>table</code><ul><li class="t1"><code>tbody</code><ul><li class="t1"><code>tr</code><ul><li class="t1"><code>td</code><ul><li class="t3"><code>#text</code>: <span title="">aaa</span></li></ul></li></ul></li></ul></li></ul></li></ul></li></ul></li></ul>
<p>The <span>stack of open elements</span> has on it the elements
<code>html</code>, <code>body</code>, <code>table</code>,
<code>tbody</code>, and the new <code>b</code> (again, note that
this doesn't match the resulting tree!); the <span>list of active
formatting elements</span> has the new <code>b</code> element in it;
and the <span>insertion mode</span> is still "<span title="insertion
mode: in table body">in table body</span>".</p>
<p>Had the character tokens been only <span title="space
character">space characters</span> instead of "bbb", then those
<span title="space character">space characters</span> would just be
appended to the <code>tbody</code> element.</p>
<p>Finally, the <code>table</code> is closed by a "table" end
tag. This pops all the nodes from the <span>stack of open
elements</span> up to and including the <code>table</code> element,
but it doesn't affect the <span>list of active formatting
elements</span>, so the "ccc" character tokens after the table
result in yet another <code>b</code> element being created, this
time after the table:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>b</code></li><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">bbb</span></li></ul></li><li class="t1"><code>table</code><ul><li class="t1"><code>tbody</code><ul><li class="t1"><code>tr</code><ul><li class="t1"><code>td</code><ul><li class="t3"><code>#text</code>: <span title="">aaa</span></li></ul></li></ul></li></ul></li></ul></li><li class="t1"><code>b</code><ul><li class="t3"><code>#text</code>: <span title="">ccc</span></li></ul></li></ul></li></ul></li></ul>
<h5>Scripts that modify the page as it is being parsed</h5>
<p><i>This section is non-normative.</i></p>
<p>Consider the following markup, which for this example we will
assume is the document with <span>URL</span> <code
title="">http://example.com/inner</code>, being rendered as the
content of an <code>iframe</code> in another document with the
<span>URL</span> <code title="">http://example.com/outer</code>:</p>
<pre><div id=a>
<script>
var div = document.getElementById('a');
parent.document.body.appendChild(div);
</script>
<script>
alert(document.URL);
</script>
</div>
<script>
alert(document.URL);
</script></pre>
<p>Up to the first "script" end tag, before the script is parsed,
the result is relatively straightforward:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>div</code> <span title="" class="t2"><code class="attribute name">id</code>="<code class="attribute value">a</code>"</span><ul><li class="t3"><code>#text</code>: <span title="">
</span></li><li class="t1"><code>script</code><ul><li class="t3"><code>#text</code>: <span title="">var div = document.getElementById('a'); ⏎ parent.document.body.appendChild(div);</span></li></ul></li></ul></li></ul></li></ul></li></ul>
<p>After the script is parsed, though, the <code>div</code> element
and its child <code>script</code> element are gone:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code></li></ul></li></ul>
<p>They are, at this point, in the <code>Document</code> of the
aforementioned outer <span>browsing context</span>. However, the
<span>stack of open elements</span> <em>still contains the
<code>div</code> element</em>.</p>
<p>Thus, when the second <code>script</code> element is parsed, it
is inserted <em>into the outer <code>Document</code>
object</em>.</p>
<p>This also means that the <span>script's global object</span> is
the outer <span>browsing context</span>'s <code>Window</code>
object, <em>not</em> the <code>Window</code> object inside the
<code>iframe</code>.</p>
<p class="note">This isn't a security problem since the script that
moves the <code>div</code> into the outer <code>Document</code> can
only do so because they have the two <code>Document</code> object
have the same <span>origin</span>.</p>
<p>Thus, the first alert says "http://example.com/outer".</p>
<p>Once the <code>div</code> element's end tag is parsed, the
<code>div</code> element is popped off the stack, and so the next
<code>script</code> element is in the inner <code>Document</code>:</p>
<ul class="domTree"><li class="t1"><code>html</code><ul><li class="t1"><code>head</code></li><li class="t1"><code>body</code><ul><li class="t1"><code>script</code><ul><li class="t3"><code>#text</code>: <span title="">alert(document.URL);</span></li></ul></li></ul></li></ul></li></ul>
<p>This second alert will say "http://example.com/inner".</p>
<h3>Namespaces</h3>
<p>The <dfn>HTML namespace</dfn> is: <code>http://www.w3.org/1999/xhtml</code></p>
<p>The <dfn>MathML namespace</dfn> is: <code>http://www.w3.org/1998/Math/MathML</code></p>
<p>The <dfn>SVG namespace</dfn> is: <code>http://www.w3.org/2000/svg</code></p>
<p>The <dfn>XLink namespace</dfn> is: <code>http://www.w3.org/1999/xlink</code></p>
<p>The <dfn>XML namespace</dfn> is: <code>http://www.w3.org/XML/1998/namespace</code></p>
<p>The <dfn>XMLNS namespace</dfn> is: <code>http://www.w3.org/2000/xmlns/</code></p>
<hr>
<p>Data mining tools and other user agents that perform operations
on <code>text/html</code> content without running scripts,
evaluating CSS or XPath expressions, or otherwise exposing the
resulting DOM to arbitrary content, may "support namespaces" by just
asserting that their DOM node analogues are in certain namespaces,
without actually exposing the above strings.</p>
<h3>Serializing HTML fragments</h3>
<p>The following steps form the <dfn>HTML fragment serialization
algorithm</dfn>. The algorithm takes as input a DOM
<code>Element</code> or <code>Document</code>, referred to as <var
title="">the node</var>, and either returns a string or raises an
exception.</p>
<p class="note">This algorithm serializes the <em>children</em> of
the node being serialized, not the node itself.</p>
<ol>
<li><p>Let <var title="">s</var> be a string, and initialize it to
the empty string.</p></li>
<li>
<p>For each child node of <var title="">the node</var>, in
<span>tree order</span>, run the following steps:
<ol>
<li><p>Let <var title="">current node</var> be the child node
being processed.</p></li>
<li>
<p>Append the appropriate string from the following list to
<var title="">s</var>:</p>
<dl class="switch">
<dt>If <var title="">current node</var> is an <code title="">Element</code></dt>
<dd>
<p>Append a U+003C LESS-THAN SIGN character character (<),
followed by the element's tag name. (For nodes created by the
<span>HTML parser</span> or <code
title="">Document.createElement()</code>, the tag name will be
lowercase.)</p>
<p>For each attribute that the element has, append a U+0020
SPACE character, the attribute's name (which, for attributes
set by the <span>HTML parser</span> or by <code
title="">Element.setAttributeNode()</code> or <code
title="">Element.setAttribute()</code>, will be lowercase), a
U+003D EQUALS SIGN character (=), a U+0022 QUOTATION MARK
character ("), the attribute's value, <span
title="escaping a string">escaped as described below</span> in
<i>attribute mode</i>, and a second U+0022 QUOTATION MARK
character (").</p>
<p>While the exact order of attributes is UA-defined, and may
depend on factors such as the order that the attributes were
given in the original markup, the sort order must be stable,
such that consecutive invocations of this algorithm serialize an
element's attributes in the same order.</p>
<p>Append a U+003E GREATER-THAN SIGN character (>).</p>
<p>If <var title="">current node</var> is an
<code>area</code>, <code>base</code>, <code>basefont</code>,
<code>bgsound</code>, <code>br</code>, <code>col</code>,
<code>embed</code>, <code>frame</code>, <code>hr</code>,
<code>img</code>, <code>input</code>, <code>keygen</code>,
<code>link</code>, <code>meta</code>, <code>param</code>, or
<code>wbr</code> element, then continue on to the next child
node at this point.</p> <!-- also, i guess: image and isindex,
but we don't list those because we don't consider those
"elements", more "macros", and thus we should never serialize
them -->
<p>If <var title="">current node</var> is a <code>pre</code>,
<code>textarea</code>, or <code>listing</code> element, append
a U+000A LINE FEED (LF) character.</p>
<p>Append the value of running the <span>HTML fragment
serialization algorithm</span> on the <var title="">current
node</var> element (thus recursing into this algorithm for
that element), followed by a U+003C LESS-THAN SIGN character
(<), a U+002F SOLIDUS character (/), the element's tag name
again, and finally a U+003E GREATER-THAN SIGN character
(>).</p>
</dd>
<dt>If <var title="">current node</var> is a <code
title="">Text</code> or <code title="">CDATASection</code>
node</dt>
<dd>
<p>If the parent of <var title="">current node</var> is a
<code>style</code>, <code>script</code>, <code>xmp</code>,
<code>iframe</code>, <code>noembed</code>,
<code>noframes</code>, or <code>plaintext</code> element, or
if the parent of <var title="">current node</var> is
<code>noscript</code> element and <span
title="concept-n-script">scripting is enabled</span> for the
node, then append the value of <var title="">current
node</var>'s <code title="">data</code> IDL attribute
literally.</p>
<p>Otherwise, append the value of <var title="">current
node</var>'s <code title="">data</code> IDL attribute, <span
title="escaping a string">escaped as described
below</span>.</p>
</dd>
<dt>If <var title="">current node</var> is a <code
title="">Comment</code></dt>
<dd>
<p>Append the literal string <code><!--</code> (U+003C
LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+002D HYPHEN-MINUS,
U+002D HYPHEN-MINUS), followed by the value of <var
title="">current node</var>'s <code title="">data</code> IDL
attribute, followed by the literal string <code>--></code>
(U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS, U+003E GREATER-THAN
SIGN).</p>
</dd>
<dt>If <var title="">current node</var> is a <code
title="">ProcessingInstruction</code></dt>
<dd>
<p>Append the literal string <code><?</code> (U+003C
LESS-THAN SIGN, U+003F QUESTION MARK), followed by the value
of <var title="">current node</var>'s <code
title="">target</code> IDL attribute, followed by a single
U+0020 SPACE character, followed by the value of <var
title="">current node</var>'s <code title="">data</code> IDL
attribute, followed by a single U+003E GREATER-THAN SIGN
character (>).</p>
</dd>
<dt>If <var title="">current node</var> is a <code title="">DocumentType</code></dt>
<dd>
<p>Append the literal string <code><!DOCTYPE</code> (U+003C
LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+0044 LATIN CAPITAL
LETTER D, U+004F LATIN CAPITAL LETTER O, U+0043 LATIN CAPITAL
LETTER C, U+0054 LATIN CAPITAL LETTER T, U+0059 LATIN CAPITAL
LETTER Y, U+0050 LATIN CAPITAL LETTER P, U+0045 LATIN CAPITAL
LETTER E), followed by a space (U+0020 SPACE), followed by the
value of <var title="">current node</var>'s <code
title="">name</code> IDL attribute, followed by the literal
string <code>></code> (U+003E GREATER-THAN SIGN).</p>
</dd>
</dl>
<p>Other node types (e.g. <code title="">Attr</code>) cannot
occur as children of elements. If, despite this, they somehow do
occur, this algorithm must raise an
<code>INVALID_STATE_ERR</code> exception.</p>
</li>
</ol>
</li>
<li><p>The result of the algorithm is the string <var
title="">s</var>.</p></li>
</ol>
<p><dfn id="escapingString">Escaping a string</dfn> (for the
purposes of the algorithm above) consists of replacing any
occurrences of the "<code title="">&</code>" character by the
string "<code title="">&amp;</code>", any occurrences of the
U+00A0 NO-BREAK SPACE character by the string "<code
title="">&nbsp;</code>", and, if the algorithm was invoked in
the <i>attribute mode</i>, any occurrences of the "<code
title="">"</code>" character by the string "<code
title="">&quot;</code>", or if it was not, any occurrences of
the "<code title=""><</code>" character by the string "<code
title="">&lt;</code>", any occurrences of the "<code
title="">></code>" character by the string "<code
title="">&gt;</code>".</p>
<p class="note">Entity reference nodes are <a
href="#entity-references">assumed to be expanded</a> by the user
agent, and are therefore not covered in the algorithm above.</p>
<p class="note">It is possible that the output of this algorithm, if
parsed with an <span>HTML parser</span>, will not return the
original tree structure. For instance, if a <code>textarea</code>
element to which a <code title="">Comment</code> node has been
appended is serialized and the output is then reparsed, the comment
will end up being displayed in the text field. Similarly, if, as a
result of DOM manipulation, an element contains a comment that
contains the literal string "<code title="">--></code>", then
when the result of serializing the element is parsed, the comment
will be truncated at that point and the rest of the comment will be
interpreted as markup. More examples would be making a
<code>script</code> element contain a text node with the text string
"<code></script></code>", or having a <code>p</code> element that
contains a <code>ul</code> element (as the <code>ul</code> element's
<span title="syntax-start-tag">start tag</span> would imply the end
tag for the <code>p</code>).</p>
<h3>Parsing HTML fragments</h3>
<p>The following steps form the <dfn>HTML fragment parsing
algorithm</dfn>. The algorithm optionally takes as input an
<code>Element</code> node, referred to as the <var
title="">context</var> element, which gives the context for the
parser, as well as <var title="">input</var>, a string to parse, and
returns a list of zero or more nodes.</p>
<p class="note">Parts marked <dfn>fragment case</dfn> in algorithms
in the parser section are parts that only occur if the parser was
created for the purposes of this algorithm (and with a <var
title="">context</var> element). The algorithms have been annotated
with such markings for informational purposes only; such markings
have no normative weight. If it is possible for a condition
described as a <span>fragment case</span> to occur even when the
parser wasn't created for the purposes of handling this algorithm,
then that is an error in the specification.</p>
<ol>
<li>
<p>Create a new <code>Document</code> node, and mark it as being
an <span title="HTML documents">HTML document</span>.</p>
</li>
<li>
<p>If there is a <var title="">context</var> element, and the
<code>Document</code> of the <var title="">context</var> element
is in <span>quirks mode</span>, then let the <code>Document</code>
be in <span>quirks mode</span>. Otherwise, if there is a <var
title="">context</var> element, and the <code>Document</code> of
the <var title="">context</var> element is in <span>limited quirks
mode</span>, then let the <code>Document</code> be in
<span>limited quirks mode</span>. Otherwise, leave the
<code>Document</code> in <span>no quirks mode</span>.</p>
</li>
<li>
<p>Create a new <span>HTML parser</span>, and associate it with
the just created <code>Document</code> node.</p>
</li>
<li>
<p>If there is a <var title="">context</var> element, run these
substeps:</p>
<ol>
<li>
<p>Set the state of the <span>HTML parser</span>'s
<span>tokenization</span> stage as follows:</p>
<dl class="switch">
<dt>If it is a <code>title</code> or <code>textarea</code>
element</dt>
<dd>Switch the tokenizer to the <span>RCDATA state</span>.</dd>
<dt>If it is a <code>style</code>, <code>script</code>,
<code>xmp</code>, <code>iframe</code>, <code>noembed</code>, or
<code>noframes</code> element</dt>
<dd>Switch the tokenizer to the <span>RAWTEXT state</span>.</dd>
<dt>If it is a <code>noscript</code> element</dt>
<dd>If the <span>scripting flag</span> is enabled, switch the
tokenizer to the <span>RAWTEXT state</span>. Otherwise,
leave the tokenizer in the <span>data state</span>.</dd>
<dt>If it is a <code>plaintext</code> element</dt>
<dd>Switch the tokenizer to the <span>PLAINTEXT
state</span>.</dd>
<dt>Otherwise</dt>
<dd>Leave the tokenizer in the <span>data state</span>.</dd>
</dl>
</li>
<li>
<p>Let <var title="">root</var> be a new <code>html</code> element
with no attributes.</p>
</li>
<li>
<p>Append the element <var title="">root</var> to the
<code>Document</code> node created above.</p>
</li>
<li>
<p>Set up the parser's <span>stack of open elements</span> so that
it contains just the single element <var title="">root</var>.</p>
</li>
<li>
<p><span title="reset the insertion mode appropriately">Reset the
parser's insertion mode appropriately</span>.</p>
<p class="note">The parser will reference the <var
title="">context</var> element as part of that algorithm.</p>
</li>
<li>
<p>Set the parser's <span><code>form</code> element pointer</span>
to the nearest node to the <var title="">context</var> element
that is a <code>form</code> element (going straight up the
ancestor chain, and including the element itself, if it is a
<code>form</code> element), or, if there is no such
<code>form</code> element, to null.</p>
</li>
</ol>
</li>
<li>
<p>Place into the <span>input stream</span> for the <span>HTML
parser</span> just created the <var title="">input</var>. The
encoding <span
title="concept-encoding-confidence">confidence</span> is
<i>irrelevant</i>.</p>
</li>
<li>
<p>Start the parser and let it run until it has consumed all the
characters just inserted into the input stream.</p>
</li>
<li>
<p>If there is a <var title="">context</var> element, return the
child nodes of <var title="">root</var>, in <span>tree
order</span>.</p>
<p>Otherwise, return the children of the <code>Document</code>
object, in <span>tree order</span>.</p>
</li>
</ol>
</div>
<h3><dfn>Named character references</dfn></h3>
<p>This table lists the character reference names that are supported
by HTML, and the code points to which they refer. It is referenced
by the previous sections.</p>
<div class="tall-and-narrow">
<table>
<thead>
<tr> <th> Name </th> <th> Character </th> </tr>
</thead>
<!--CHARACTER-REFERENCES-->
</table>
<!--
If we want to add character references, Almorca suggests:
> I would add &sub1; (character U+2081), &sub2;
> (character U+2082) and &sub3; (character U+2083). They
> would are the equivalent to ¹, ², and ³.
See also: http://www.w3.org/2003/entities/
-->
</div>
<h2><dfn id="xhtml">The XHTML syntax</dfn></h2>
<p class="note">This section only describes the rules for XML
resources. Rules for <code>text/html</code> resources are discussed
in the section above entitled "<span>The HTML syntax</span>".</p>
<div class="impl">
<h3>Writing XHTML documents</h3>
</div>
<p>The syntax for using HTML with XML, whether in XHTML documents or
embedded in other XML documents, is defined in the XML and
Namespaces in XML specifications. <a href="#refsXML">[XML]</a> <a
href="#refsXMLNS">[XMLNS]</a></p>
<p>This specification does not define any syntax-level requirements
beyond those defined for XML proper.</p>
<p>XML documents may contain a <code>DOCTYPE</code> if desired, but
this is not required to conform to this specification. This
specification does not define a public or system identifier, nor
provide a format DTD.</p>
<p class="note">According to the XML specification, XML processors
are not guaranteed to process the external DTD subset referenced in
the DOCTYPE. This means, for example, that using entity references
for characters in XHTML documents is unsafe if they are defined in
an external file (except for <code title="">&lt;</code>, <code
title="">&gt;</code>, <code title="">&amp;</code>, <code
title="">&quot;</code> and <code
title="">&apos;</code>).</p>
<div class="impl">
<h3>Parsing XHTML documents</h3>
<p>This section describes the relationship between XML and the DOM,
with a particular emphasis on how this interacts with HTML.</p>
<p>An <dfn>XML parser</dfn>, for the purposes of this specification,
is a construct that follows the rules given in the XML specification
to map a string of bytes or characters into a <code>Document</code>
object.</p>
<p>An <span>XML parser</span> is either associated with a
<code>Document</code> object when it is created, or creates one
implicitly.</p>
<p>This <code>Document</code> must then be populated with DOM nodes
that represent the tree structure of the input passed to the parser,
as defined by the XML specification, the Namespaces in XML
specification, and the DOM Core specification. DOM mutation events
must not fire for the operations that the <span>XML parser</span>
performs on the <code>Document</code>'s tree, but the user agent
must act as if elements and attributes were individually appended
and set respectively so as to trigger rules in this specification
regarding what happens when an element in inserted into a document
or has its attributes set. <a href="#refsXML">[XML]</a> <a
href="#refsXMLNS">[XMLNS]</a> <a href="#refsDOMCORE">[DOMCORE]</a>
<a href="#refsDOMEVENTS">[DOMEVENTS]</a></p>
<p>Certain algorithms in this specification <dfn title="feed the
parser">spoon-feed the parser</dfn> characters one string at a
time. In such cases, the <span>XML parser</span> must act as it
would have if faced with a single string consisting of the
concatenation of all those characters.</p>
<p>When an <span>XML parser</span> creates a <code>script</code>
element, it must be marked as being <span>"parser-inserted"</span>.
If the parser was originally created for the <span>XML fragment
parsing algorithm</span>, then the element must be marked as
<span>"already started"</span> also. When the element's end tag is
parsed, the user agent must <span title="running a
script">run</span> the <code>script</code> element. If this causes
there to be a <span>pending parsing-blocking script</span>, then the
user agent must run the following steps:</p>
<ol>
<li><p>Block this instance of the <span>XML parser</span>, such
that the <span>event loop</span> will not run <span
title="concept-task">tasks</span> that invoke it.</p></li>
<li><p><span>Spin the event loop</span> until there is no <span
title="a style sheet blocking scripts">style sheet blocking
scripts</span> and the <span>pending parsing-blocking
script</span>'s <span>"ready to be parser-executed"</span> flag is
set.</p></li>
<li><p>Unblock this instance of the <span>XML parser</span>, such
that <span title="concept-task">tasks</span> that invoke it can
again be run.</p></li>
<li><p><span title="executing a script block">Execute</span> the
<span>pending parsing-blocking script</span>.</p></li>
<li><p>There is no longer a <span>pending parsing-blocking
script</span>.</p></li>
</ol>
<p class="note">Since the <code
title="dom-document-write">document.write()</code> API is not
available for <span>XML documents</span>, much of the complexity in
the <span>HTML parser</span> is not needed in the <span>XML
parser</span>.</p>
<p>When an <span>XML parser</span> reaches the end of its input, it
must <span>stop parsing</span>, following the same rules as the
<span>HTML parser</span>.</p>
<p>For the purposes of conformance checkers, if a resource is
determined to be in <span>the XHTML syntax</span>, then it is an
<span title="XML documents">XML document</span>.</p>
<h3>Serializing XHTML fragments</h3>
<p>The <dfn>XML fragment serialization algorithm</dfn> for a
<code>Document</code> or <code>Element</code> node either returns a
fragment of XML that represents that node or raises an
exception.</p>
<p>For <code>Document</code>s, the algorithm must return a string in
the form of a <a
href="http://www.w3.org/TR/xml/#sec-well-formed">document
entity</a>, if none of the error cases below apply.</p>
<p>For <code>Element</code>s, the algorithm must return a string in
the form of an <a
href="http://www.w3.org/TR/xml/#wf-entities">internal general parsed
entity</a>, if none of the error cases below apply.</p>
<p>In both cases, the string returned must be XML
namespace-well-formed and must be an isomorphic serialization of all
of that node's child nodes, in <span>tree order</span>. User agents
may adjust prefixes and namespace declarations in the serialization
(and indeed might be forced to do so in some cases to obtain
namespace-well-formed XML). User agents may use a combination of
regular text, character references, and CDATA sections to represent
<span title="text node">text nodes</span> in the DOM (and indeed
might be forced to use representations that don't match the DOM's,
e.g. if a <code>CDATASection</code> node contains the string "<code
title="">]]></code>").</p>
<p>For <code>Element</code>s, if any of the elements in the
serialization are in no namespace, the default namespace in scope
for those elements must be explicitly declared as the empty
string.<!-- because otherwise round-tripping might break since it'll
pick up the surrounding default ns when setting --> (This doesn't
apply in the <code>Document</code> case.) <a
href="#refsXML">[XML]</a> <a href="#refsXMLNS">[XMLNS]</a></p>
<p>For the purposes of this section, an internal general parsed
entity is considered XML namespace-well-formed if a document
consisting of an element with no namespace declarations whose
contents are the internal general parsed entity would itself be XML
namespace-well-formed.</p>
<p>If any of the following error cases are found in the DOM subtree
being serialized, then the algorithm must raise an
<code>INVALID_STATE_ERR</code> exception instead of returning a
string:</p>
<ul>
<li>A <code>Document</code> node with no child element nodes.</li>
<li>A <code>DocumentType</code> node that has an external subset
public identifier that contains characters that are not matched by
the XML <code title="">PubidChar</code> production. <a
href="#refsXML">[XML]</a></li>
<li>A <code>DocumentType</code> node that has an external subset
system identifier that contains both a U+0022 QUOTATION MARK (")
and a U+0027 APOSTROPHE (') or that contains characters that are
not matched by the XML <code title="">Char</code> production. <a
href="#refsXML">[XML]</a></li>
<li>A node with a <!--prefix or--> local name containing a U+003A
COLON (:).</li> <!--(prefixes can get adjusted, so this isn't an
excuse) -->
<li>A node with a <!--prefix or--> local name that does not match
the XML <code title="">Name</code> production. <a
href="#refsXML">[XML]</a></li> <!--(again, prefixes can get
adjusted, so this isn't an excuse) -->
<li>An <code>Attr</code> node with no namespace whose local name is
the lowercase string "<code title="">xmlns</code>". <a
href="#refsXMLNS">[XMLNS]</a></li>
<li>An <code>Element</code> node with two or more attributes with
the same local name and namespace.</li>
<li>An <code>Attr</code> node, <code>Text</code> node,
<code>CDATASection</code> node, <code>Comment</code> node, or
<code>ProcessingInstruction</code> node whose data contains
characters that are not matched by the XML <code
title="">Char</code> production. <a href="#refsXML">[XML]</a></li>
<!--<li>A <code>CDATASection</code> node whose data contains the
string "<code title="">]]></code>".</li> (these can be split)-->
<li>A <code>Comment</code> node whose data contains two adjacent
U+002D HYPHEN-MINUS characters (-) or ends with such a
character.</li>
<li>A <code>ProcessingInstruction</code> node whose target name is
an <span>ASCII case-insensitive</span> match for the string "<code
title="">xml</code>".</li>
<li>A <code>ProcessingInstruction</code> node whose target name
contains a U+003A COLON (:).</li>
<li>A <code>ProcessingInstruction</code> node whose data contains
the string "<code title="">?></code>".</li>
</ul>
<p class="note">These are the only ways to make a DOM
unserializable. The DOM enforces all the other XML constraints; for
example, trying to append two elements to a <code>Document</code>
node will raise a <code>HIERARCHY_REQUEST_ERR</code> exception.</p>
<h3>Parsing XHTML fragments</h3>
<p>The <dfn>XML fragment parsing algorithm</dfn> for either returns
a <code>Document</code> or raises a <code>SYNTAX_ERR</code>
exception. Given a string <var title="">input</var> and an optional
context element <var title="">context</var>, the algorithm is as
follows:</p>
<ol>
<li>
<p>Create a new <span>XML parser</span>.</p>
</li>
<li>
<p>If there is a <var title="">context</var> element, <span>feed
the parser</span> just created the string corresponding to the
start tag of that element, declaring all the namespace prefixes
that are in scope on that element in the DOM, as well as declaring
the default namespace (if any) that is in scope on that element in
the DOM.</p>
<p>A namespace prefix is in scope if the DOM Core <code
title="">lookupNamespaceURI()</code> method on the element would
return a non-null value for that prefix.</p>
<p>The default namespace is the namespace for which the DOM Core
<code title="">isDefaultNamespace()</code> method on the element
would return true.</p>
</li>
<li>
<p><span>Feed the parser</span> just created the string <var
title="">input</var>.</p>
</li>
<li>
<p>If there is a <var title="">context</var> element, <span>feed
the parser</span> just created the string corresponding to the
end tag of that element.</p>
</li>
<li>
<p>If there is an XML well-formedness or XML namespace
well-formedness error, then raise a <code>SYNTAX_ERR</code>
exception and abort these steps.</p>
</li>
<li>
<p>If there is a <var title="">context</var> element, then return
the child nodes of the root element of the resulting
<code>Document</code>, in <span>tree order</span>.</p>
<p>Otherwise, return the children of the <code>Document</code>
object, in <span>tree order</span>.</p>
</li>
</ol>
</div>
<div class="impl">
<h2 id="rendering">Rendering</h2>
<p><i>User agents are not required to present HTML documents in any
particular way. However, this section provides a set of suggestions
for rendering HTML documents that, if followed, are likely to lead
to a user experience that closely resembles the experience intended
by the documents' authors. So as to avoid confusion regarding the
normativity of this section, RFC2119 terms have not been used.
Instead, the term "expected" is used to indicate behavior that will
lead to this experience.</i></p>
<h3>Introduction</h3>
<p>In general, user agents are expected to support CSS, and many of
the suggestions in this section are expressed in CSS terms. User
agents that use other presentation mechanisms can derive their
expected behavior by translating from the CSS rules given in this
section.</p>
<p>In the absence of style-layer rules to the contrary (e.g. author
style sheets), user agents are expected to render an element so that
it conveys to the user the meaning that the element
<dfn>represents</dfn>, as described by this specification.</p>
<p>The suggestions in this section generally assume a visual output
medium with a resolution of 96dpi or greater, but HTML is intended
to apply to multiple media (it is a <i>media-independent</i>
language). User agents are encouraged to adapt the suggestions in
this section to their target media.</p>
<hr>
<p>An element is <dfn>being rendered</dfn> if it is <span>in a
<code>Document</code></span>, either its parent node is itself
<span>being rendered</span> or it is the <code>Document</code> node,
and it is not explicitly excluded from the rendering using the CSS
'display' property's 'none' value or equivalent in other styling
languages.</p>
<p class="note">Just being off-screen does not mean the element is
not <span>being rendered</span>. The presence of the <code
title="attr-hidden">hidden</code> attribute normally means the
element is not <span>being rendered</span>, though this might be
overriden by the style sheets.</p>
</div>
<div class="impl">
<h3>The CSS user agent style sheet and presentational hints</h3>
<h4>Introduction</h4>
<p>The CSS rules given in these subsections are, except where
otherwise specified, expected to be used as part of the user-agent
level style sheet defaults for all documents that contain <span>HTML
elements</span>.</p>
<p>Some rules are intended for the author-level zero-specificity
presentational hints part of the CSS cascade; these are explicitly
called out as <dfn>presentational hints</dfn>.</p>
<p>Some of the rules regarding left and right margins are given here
as appropriate for elements whose 'direction' property is 'ltr', and
are expected to be flipped around on elements whose 'direction'
property is 'rtl'. These are marked "<dfn>LTR-specific</dfn>".</p>
<hr>
<p>When the text below says that an attribute <var
title="">attribute</var> on an element <var title="">element</var>
<dfn>maps to the pixel length property</dfn> (or properties) <var
title="">properties</var>, it means that if <var
title="">element</var> has an attribute <var
title="">attribute</var> set, and parsing that attribute's value
using the <span>rules for parsing non-negative integers</span>
doesn't generate an error, then the user agent is expected to use
the parsed value as a pixel length for a <span title="presentational
hints">presentational hint</span> for <var
title="">properties</var>.</p>
<p>When the text below says that an attribute <var
title="">attribute</var> on an element <var title="">element</var>
<dfn>maps to the dimension property</dfn> (or properties) <var
title="">properties</var>, it means that if <var
title="">element</var> has an attribute <var
title="">attribute</var> set, and parsing that attribute's value
using the <span>rules for parsing dimension values</span> doesn't
generate an error, then the user agent is expected to use the parsed
dimension as the value for a <span title="presentational
hints">presentational hint</span> for <var
title="">properties</var>, with the value given as a pixel length if
the dimension was an integer, and with the value given as a
percentage if the dimension was a percentage.</p>
</div>
<div class="impl">
<h4>Display types</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
[hidden], area, base, basefont, command, datalist, head,
input[type=hidden], link, menu[type=context], meta, noembed, noframes,
param, rp, script, source, style, title {
display: none;
}
address, article, aside, blockquote, body, center, dd, dir, div, dl,
dt, figure, footer, form, h1, h2, h3, h4, h5, h6, header, hgroup, hr,
html, legend, listing, menu, nav, ol, p, plaintext, pre, section, ul,
xmp { display: block; }
table { display: table; }
caption { display: table-caption; }
colgroup { display: table-column-group; }
col { display: table-column; }
thead { display: table-header-group; }
tbody { display: table-row-group; }
tfoot { display: table-footer-group; }
tr { display: table-row; }
td, th { display: table-cell; }
li { display: list-item; }
ruby { display: ruby; }
rt { display: ruby-text; }</pre>
<!-- del, ins, and map are inline. -->
<p>For the purposes of the CSS table model, the <code>col</code>
element is expected to be treated as if it was present as many times
as its <code title="attr-col-span">span</code> attribute <span
title="rules for parsing non-negative
integers">specifies</span>.</p>
<p>For the purposes of the CSS table model, the
<code>colgroup</code> element, if it contains no <code>col</code>
element, is expected to be treated as if it had as many such
children as its <code title="attr-colgroup-span">span</code>
attribute <span title="rules for parsing non-negative
integers">specifies</span>.</p>
<p>For the purposes of the CSS table model, the <code
title="attr-tdth-colspan">colspan</code> and <code
title="attr-tdth-rowspan">rowspan</code> attributes on
<code>td</code> and <code>th</code> elements are expected to <span
title="rules for parsing non-negative integers">provide</span> the
<i>special knowledge</i> regarding cells spanning rows and
columns.</p>
<p>For the purposes of the CSS ruby model, runs of descendants of
<code>ruby</code> elements that are not <code>rt</code> or
<code>rp</code> elements are expected to be wrapped in anonymous
boxes whose 'display' property has the value 'ruby-base'.</p>
<p>User agents that do not support correct ruby rendering are
expected to render parentheses around the text of <code>rt</code>
elements in the absence of <code>rp</code> elements.</p>
<p>The <code>br</code> element is expected to render as if its
contents were a single U+000A LINE FEED (LF) character and its
'white-space' property was 'pre'. User agents are expected to
support the 'clear' property on inline elements (in order to render
<code>br</code> elements with <code
title="attr-br-clear">clear</code> attributes) in the manner
described in the non-normative note to this effect in CSS2.1.</p>
<!-- section 9.5.2 of CSS2.1 -->
<p>The user agent is expected to hide <code>noscript</code> elements
for whom <span title="concept-n-script">scripting is enabled</span>,
irrespective of CSS rules.</p>
<p>In <span>HTML documents</span>, the user agent is expected to
hide <code>form</code> elements that are children of
<code>table</code>, <code>thead</code>, <code>tbody</code>,
<code>tfoot</code>, or <code>tr</code> elements, irrespective of CSS
rules.</p>
</div>
<div class="impl">
<h4>Margins and padding</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
blockquote, dir, dl, figure, listing, menu, ol, p, plaintext,
pre, ul, xmp {
margin-top: 1em; margin-bottom: 1em;
}
dir dir, dir dl, dir menu, dir ol, dir ul,
dl dir, dl dl, dl menu, dl ol, dl ul,
menu dir, menu dl, menu menu, menu ol, menu ul,
ol dir, ol dl, ol menu, ol ol, ol ul,
ul dir, ul dl, ul menu, ul ol, ul ul {
margin-top: 0; margin-bottom: 0;
}
h1 { margin-top: 0.67em; margin-bottom; 0.67em; }
h2 { margin-top: 0.83em; margin-bottom; 0.83em; }
h3 { margin-top: 1.00em; margin-bottom; 1.00em; }
h4 { margin-top: 1.33em; margin-bottom; 1.33em; }
h5 { margin-top: 1.67em; margin-bottom; 1.67em; }
h6 { margin-top: 2.33em; margin-bottom; 2.33em; }
dd { margin-left: 40px; } /* <span>LTR-specific</span>: use 'margin-right' for rtl elements */
details > dd, figure > dd { margin-left: 0; } /* <span>LTR-specific</span>: use 'margin-right' for rtl elements */
dir, menu, ol, ul { padding-left: 40px; } /* <span>LTR-specific</span>: use 'padding-right' for rtl elements */
blockquote, figure { margin-left: 40px; margin-right: 40px; }
table { border-spacing: 2px; border-collapse: separate; }
td, th { padding: 1px; }</pre>
<p>The <code>article</code>, <code>aside</code>, <code>nav</code>,
and <code>section</code> elements are expected to affect the margins
of <code>h1</code> elements, based on the nesting depth. If <var
title="">x</var> is a selector that matches elements that are either
<code>article</code>, <code>aside</code>, <code>nav</code>, or
<code>section</code> elements, then the following rules capture what
is expected:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
<var title="">x</var> h1 { margin-top: 0.83em; margin-bottom: 0.83em; }
<var title="">x</var> <var title="">x</var> h1 { margin-top: 1.00em; margin-bottom: 1.00em; }
<var title="">x</var> <var title="">x</var> <var title="">x</var> h1 { margin-top: 1.33em; margin-bottom: 1.33em; }
<var title="">x</var> <var title="">x</var> <var title="">x</var> <var title="">x</var> h1 { margin-top: 1.67em; margin-bottom: 1.67em; }
<var title="">x</var> <var title="">x</var> <var title="">x</var> <var title="">x</var> <var title="">x</var> h1 { margin-top: 2.33em; margin-bottom: 2.33em; }</pre>
<hr>
<p>For each property in the table below, given a <code>body</code>
element, the first attribute that exists <span>maps to the pixel
length property</span> on the <code>body</code> element. If none of
the attributes for a property are found, or if the value of the
attribute that was found cannot be parsed successfully, then a
default value of 8px is expected to be used for that property
instead.</p>
<table>
<thead>
<tr>
<th>Property
<th>Source
<tbody>
<tr>
<td rowspan="3">'margin-top'
<td><code>body</code> element's <code title="attr-body-marginheight">marginheight</code> attribute
<tr>
<td>The <code>body</code> element's <span>container frame element</span>'s <code title="attr-frame-marginheight">marginheight</code> attribute
<tr>
<td><code>body</code> element's <code title="attr-body-topmargin">topmargin</code> attribute
<tbody>
<tr>
<td rowspan="3">'margin-right'
<td><code>body</code> element's <code title="attr-body-marginwidth">marginwidth</code> attribute
<tr>
<td>The <code>body</code> element's <span>container frame element</span>'s <code title="attr-frame-marginwidth">marginwidth</code> attribute
<tr>
<td><code>body</code> element's <code title="attr-body-rightmargin">rightmargin</code> attribute
<tbody>
<tr>
<td rowspan="3">'margin-bottom'
<td><code>body</code> element's <code title="attr-body-marginheight">marginheight</code> attribute
<tr>
<td>The <code>body</code> element's <span>container frame element</span>'s <code title="attr-frame-marginheight">marginheight</code> attribute
<tr>
<td><code>body</code> element's <code title="attr-body-bottommargin">topmargin</code> attribute
<tbody>
<tr>
<td rowspan="3">'margin-left'
<td><code>body</code> element's <code title="attr-body-marginwidth">marginwidth</code> attribute
<tr>
<td>The <code>body</code> element's <span>container frame element</span>'s <code title="attr-frame-marginwidth">marginwidth</code> attribute
<tr>
<td><code>body</code> element's <code title="attr-body-leftmargin">rightmargin</code> attribute
</table>
<p>If the <code>body</code> element's <code>Document</code>'s
<span>browsing context</span> is a <span>nested browsing
context</span>, and the <span>browsing context container</span> of
that <span>nested browsing context</span> is a <code>frame</code> or
<code>iframe</code> element, then the <dfn>container frame
element</dfn> of the <code>body</code> element is that
<code>frame</code> or <code>iframe</code> element. Otherwise, there
is no <span>container frame element</span>.</p>
<p class="warning">The above requirements imply that a page can
change the margins of another page (including one from another
<span>origin</span>) using, for example, an
<code>iframe</code>. This is potentially a security risk, as it
might in some cases allow an attack to contrive a situation in which
a page is rendered not as the author intended, possibly for the
purposes of phishing or otherwise misleading the user.</p>
<hr>
<p>If the <code>Document</code> has a <span>root element</span>, and
the <code>Document</code>'s <span>browsing context</span> is a
<span>nested browsing context</span>, and the <span>browsing context
container</span> of that <span>nested browsing context</span> is a
<code>frame</code> or <code>iframe</code> element, and that element
has a <code title="attr-frames-scrolling">scrolling</code>
attribute, then the user agent is expected to compare the value of
the attribute in an <span>ASCII case-insensitive</span> manner to
the values in the first column of the following table, and if one of
them matches, then the user agent is expected to treat that
attribute as a <span title="presentational hints">presentational
hint</span> for the aforementioned root element's 'overflow'
property, setting it to the value given in the corresponding cell on
the same row in the second column:</p>
<table>
<thead>
<tr>
<th> Attribute value
<th> 'overflow' value
<tbody>
<tr>
<td><code title="">on</code>
<td>'scroll'
<tr>
<td><code title="">scroll</code>
<td>'scroll'
<tr>
<td><code title="">yes</code>
<td>'scroll'
<tr>
<td><code title="">off</code>
<td>'hidden'
<tr>
<td><code title="">noscroll</code>
<td>'hidden'
<tr>
<td><code title="">no</code>
<td>'hidden'
<tr>
<td><code title="">auto</code>
<td>'auto'
</table>
<hr>
<p>The <code>table</code> element's <code
title="attr-table-cellspacing">cellspacing</code> attribute
<span>maps to the pixel length property</span> 'border-spacing' on the
element.</p>
<p>The <code>table</code> element's <code
title="attr-table-cellpadding">cellpadding</code> attribute <span
title="maps to the pixel length property">maps to the pixel length
properties</span> 'padding-top', 'padding-right', 'padding-bottom',
and 'padding-left' of any <code>td</code> and <code>th</code>
elements that have corresponding <span
title="concept-cell">cells</span> in the <span
title="concept-table">table</span> corresponding to the
<code>table</code> element.</p>
<p>The <code>table</code> element's <code
title="attr-table-hspace">hspace</code> attribute <span title="maps
to the dimension property">maps to the dimension properties</span>
'margin-left' and 'margin-right' on the <code>table</code>
element.</p>
<p>The <code>table</code> element's <code
title="attr-table-vspace">vspace</code> attribute <span title="maps
to the dimension property">maps to the dimension properties</span>
'margin-top' and 'margin-bottom' on the <code>table</code>
element.</p>
<p>The <code>table</code> element's <code
title="attr-table-height">height</code> attribute <span>maps to the
dimension property</span> 'height' on the <code>table</code>
element.</p>
<p>The <code>table</code> element's <code
title="attr-table-width">width</code> attribute <span>maps to the
dimension property</span> 'width' on the <code>table</code>
element.</p>
<p>The <code>col</code> element's <code
title="attr-col-width">width</code> attribute <span>maps to the
dimension property</span> 'width' on the <code>col</code>
element.</p>
<p>The <code>tr</code> element's <code
title="attr-tr-height">height</code> attribute <span>maps to the
dimension property</span> 'height' on the <code>tr</code>
element.</p>
<p>The <code>td</code> and <code>th</code> elements' <code
title="attr-tdth-height">height</code> attributes <span title="maps
to the dimension property">map to the dimension property</span> 'height'
on the element.</p>
<p>The <code>td</code> and <code>th</code> elements' <code
title="attr-tdth-width">width</code> attributes <span title="maps
to the dimension property">map to the dimension property</span> 'width'
on the element.</p>
<hr>
<p>In <span>quirks mode</span>, the following rules are also
expected to apply:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
form { margin-bottom: 1em; }</pre>
<p>When a <code>Document</code> is in <span>quirks mode</span>,
margins on <span>HTML elements</span> at the top or bottom of
<code>body</code>, <code>td</code>, or <code>th</code> elements are
expected to be collapsed to zero.</p>
</div>
<div class="impl">
<h4>Alignment</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
thead, tbody, tfoot, table > tr { vertical-align: middle; }
tr, td, th { vertical-align: inherit; }
sub { vertical-align: sub; }
sup { vertical-align: super; }
th { text-align: center; }</pre>
<hr>
<p>The following rules are also expected to apply, as
<span>presentational hints</span>:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
table[align=left] { float: left; }
table[align=right] { float: right; }
table[align=center], table[align=abscenter],
table[align=absmiddle], table[align=middle] {
margin-left: auto; margin-right: auto;
}
caption[align=bottom] { caption-side: bottom; }
p[align=left], h1[align=left], h2[align=left], h3[align=left],
h4[align=left], h5[align=left], h6[align=left] {
text-align: left;
}
p[align=right], h1[align=right], h2[align=right], h3[align=right],
h4[align=right], h5[align=right], h6[align=right] {
text-align: right;
}
p[align=center], h1[align=center], h2[align=center], h3[align=center],
h4[align=center], h5[align=center], h6[align=center] {
text-align: center;
}
p[align=justify], h1[align=justify], h2[align=justify], h3[align=justify],
h4[align=justify], h5[align=justify], h6[align=justify] {
text-align: justify;
}
col[valign=top], thead[valign=top], tbody[valign=top],
tfoot[valign=top], tr[valign=top], td[valign=top], th[valign=top] {
vertical-align: top;
}
col[valign=middle], thead[valign=middle], tbody[valign=middle],
tfoot[valign=middle], tr[valign=middle], td[valign=middle], th[valign=middle] {
vertical-align: middle;
}
col[valign=bottom], thead[valign=bottom], tbody[valign=bottom],
tfoot[valign=bottom], tr[valign=bottom], td[valign=bottom], th[valign=bottom] {
vertical-align: bottom;
}
col[valign=baseline], thead[valign=baseline], tbody[valign=baseline],
tfoot[valign=baseline], tr[valign=baseline], td[valign=baseline], th[valign=baseline] {
vertical-align: baseline;
}</pre>
<p>The <code>center</code> element, the <code>caption</code> element
unless specified otherwise below, and the <code>div</code> element
when its <code title="attr-div-align">align</code> attribute's value
is an <span>ASCII case-insensitive</span> match for the string
"<code title="">center</code>", are expected to center text within
themselves, as if they had their 'text-align' property set to
'center' in a <span title="presentational hints">presentational
hint</span>, and to <span>align descendants</span> to the center.</p>
<p>The <code>div</code>, <code>caption</code>, <code>thead</code>,
<code>tbody</code>, <code>tfoot</code>, <code>tr</code>,
<code>td</code>, and <code>th</code> elements, when they have an
<code title="attr-align">align</code> attribute whose value is an
<span>ASCII case-insensitive</span> match for the string "<code
title="">left</code>", are expected to left-align text within
themselves, as if they had their 'text-align' property set to 'left'
in a <span title="presentational hints">presentational hint</span>,
and to <span>align descendants</span> to the left.</p>
<p>The <code>div</code>, <code>caption</code>, <code>thead</code>,
<code>tbody</code>, <code>tfoot</code>, <code>tr</code>,
<code>td</code>, and <code>th</code> elements, when they have an
<code title="attr-align">align</code> attribute whose value is an
<span>ASCII case-insensitive</span> match for the string "<code
title="">right</code>", are expected to right-align text within
themselves, as if they had their 'text-align' property set to
'right' in a <span title="presentational hints">presentational
hint</span>, and to <span>align descendants</span> to the right.</p>
<p>The <code>div</code>, <code>caption</code>, <code>thead</code>,
<code>tbody</code>, <code>tfoot</code>, <code>tr</code>,
<code>td</code>, and <code>th</code> elements, when they have an
<code title="attr-align">align</code> attribute whose value is an
<span>ASCII case-insensitive</span> match for the string "<code
title="">justify</code>", are expected to full-justify text within
themselves, as if they had their 'text-align' property set to
'justify' in a <span title="presentational hints">presentational
hint</span>, and to <span>align descendants</span> to the left.</p>
<p>When a user agent is to <dfn>align descendants</dfn> of a node,
the user agent is expected to align only those descendants that have
both their 'margin-left' and 'margin-right' properties computing to
a value other than 'auto', that are over-constrained and that have
one of those two margins with a used value forced to a greater
value, and that do not themselves have an applicable <code
title="attr-align">align</code> attribute.</p>
</div>
<div class="impl">
<h4>Fonts and colors</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
address, cite, dfn, em, i, var { font-style: italic; }
b, strong, th { font-weight: bold; }
code, kbd, listing, plaintext, pre, samp, tt, xmp { font-family: monospace; }
h1 { font-size: 2.00em; font-weight: bold; }
h2 { font-size: 1.50em; font-weight: bold; }
h3 { font-size: 1.17em; font-weight: bold; }
h4 { font-size: 1.00em; font-weight: bold; }
h5 { font-size: 0.83em; font-weight: bold; }
h6 { font-size: 0.67em; font-weight: bold; }
big { font-size: larger; }
small, sub, sup { font-size: smaller; }
sub, sup { line-height: normal; }
:link { color: blue; }
:visited { color: purple; }
mark { background: yellow; color: black; }
table, td, th { border-color: gray; }
thead, tbody, tfoot, tr { border-color: inherit; }
table[rules=none], table[rules=groups], table[rules=rows],
table[rules=cols], table[rules=all], table[frame=void],
table[frame=above], table[frame=below], table[frame=hsides],
table[frame=lhs], table[frame=rhs], table[frame=vsides],
table[frame=box], table[frame=border],
table[rules=none] > tr > td, table[rules=none] > tr > th,
table[rules=groups] > tr > td, table[rules=groups] > tr > th,
table[rules=rows] > tr > td, table[rules=rows] > tr > th,
table[rules=cols] > tr > td, table[rules=cols] > tr > th,
table[rules=all] > tr > td, table[rules=all] > tr > th,
table[rules=none] > thead > tr > td, table[rules=none] > thead > tr > th,
table[rules=groups] > thead > tr > td, table[rules=groups] > thead > tr > th,
table[rules=rows] > thead > tr > td, table[rules=rows] > thead > tr > th,
table[rules=cols] > thead > tr > td, table[rules=cols] > thead > tr > th,
table[rules=all] > thead > tr > td, table[rules=all] > thead > tr > th,
table[rules=none] > tbody > tr > td, table[rules=none] > tbody > tr > th,
table[rules=groups] > tbody > tr > td, table[rules=groups] > tbody > tr > th,
table[rules=rows] > tbody > tr > td, table[rules=rows] > tbody > tr > th,
table[rules=cols] > tbody > tr > td, table[rules=cols] > tbody > tr > th,
table[rules=all] > tbody > tr > td, table[rules=all] > tbody > tr > th,
table[rules=none] > tfoot > tr > td, table[rules=none] > tfoot > tr > th,
table[rules=groups] > tfoot > tr > td, table[rules=groups] > tfoot > tr > th,
table[rules=rows] > tfoot > tr > td, table[rules=rows] > tfoot > tr > th,
table[rules=cols] > tfoot > tr > td, table[rules=cols] > tfoot > tr > th,
table[rules=all] > tfoot > tr > td, table[rules=all] > tfoot > tr > th {
border-color: black;
}</pre>
<hr>
<p>The initial value for the 'color' property is expected to be
black. The initial value for the 'background-color' property is
expected to be 'transparent'. The canvas's background is expected to
be white.</p>
<hr>
<p>The <code>article</code>, <code>aside</code>, <code>nav</code>,
and <code>section</code> elements are expected to affect the font
size of <code>h1</code> elements, based on the nesting depth. If
<var title="">x</var> is a selector that matches elements that are
either <code>article</code>, <code>aside</code>, <code>nav</code>,
or <code>section</code> elements, then the following rules capture
what is expected:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
<var title="">x</var> h1 { font-size: 1.50em; }
<var title="">x</var> <var title="">x</var> h1 { font-size: 1.17em; }
<var title="">x</var> <var title="">x</var> <var title="">x</var> h1 { font-size: 1.00em; }
<var title="">x</var> <var title="">x</var> <var title="">x</var> <var title="">x</var> h1 { font-size: 0.83em; }
<var title="">x</var> <var title="">x</var> <var title="">x</var> <var title="">x</var> <var title="">x</var> h1 { font-size: 0.67em; }</pre>
<hr>
<p>When a <code>body</code>, <code>table</code>, <code>thead</code>,
<code>tbody</code>, <code>tfoot</code>, <code>tr</code>,
<code>td</code>, or <code>th</code> element has a <code
title="attr-background">background</code> attribute set to a
non-empty value, the new value is expected to be <span
title="resolve a url">resolved</span> relative to the element, and
if this is successful, the user agent is expected to treat the
attribute as a <span title="presentational hints">presentational
hint</span> setting the element's 'background-image' property to the
resulting <span>absolute URL</span>.</p>
<p>When a <code>body</code>, <code>table</code>, <code>thead</code>,
<code>tbody</code>, <code>tfoot</code>, <code>tr</code>,
<code>td</code>, or <code>th</code> element has a <code
title="attr-bgcolor">bgcolor</code> attribute set, the new value is
expected to be parsed using the <span>rules for parsing a legacy
color value</span>, and if that does not return an error, the user
agent is expected to treat the attribute as a <span
title="presentational hints">presentational hint</span> setting the
element's 'background-color' property to the resulting color.</p>
<p>When a <code>body</code> element has a <code
title="attr-body-text">text</code> attribute, its value is expected
to be parsed using the <span>rules for parsing a legacy color
value</span>, and if that does not return an error, the user
agent is expected to treat the attribute as a <span
title="presentational hints">presentational hint</span> setting the
element's 'color' property to the resulting color.</p>
<p>When a <code>body</code> element has a <code
title="attr-body-link">link</code> attribute, its value is expected
to be parsed using the <span>rules for parsing a legacy color
value</span>, and if that does not return an error, the user agent
is expected to treat the attribute as a <span title="presentational
hints">presentational hint</span> setting the 'color' property of
any element in the <code>Document</code> matching the ':link'
pseudo-class to the resulting color.</p>
<p>When a <code>body</code> element has a <code
title="attr-body-vlink">vlink</code> attribute, its value is
expected to be parsed using the <span>rules for parsing a legacy
color value</span>, and if that does not return an error, the user
agent is expected to treat the attribute as a <span
title="presentational hints">presentational hint</span> setting the
'color' property of any element in the <code>Document</code>
matching the ':visited' pseudo-class to the resulting color.</p>
<p>When a <code>body</code> element has a <code
title="attr-body-alink">alink</code> attribute, its value is
expected to be parsed using the <span>rules for parsing a legacy
color value</span>, and if that does not return an error, the user
agent is expected to treat the attribute as a <span
title="presentational hints">presentational hint</span> setting the
'color' property of any element in the <code>Document</code>
matching the ':active' pseudo-class and either the ':link'
pseudo-class or the ':visited' pseudo-class to the resulting
color.</p>
<p>When a <code>table</code> element has a <code
title="attr-table-bordercolor">bordercolor</code> attribute, its
value is expected to be parsed using the <span>rules for parsing a
legacy color value</span>, and if that does not return an error, the
user agent is expected to treat the attribute as a <span
title="presentational hints">presentational hint</span> setting the
element's 'border-top-color', 'border-right-color',
'border-bottom-color', and 'border-right-color' properties to the
resulting color.</p>
<hr>
<p>When a <code>font</code> element has a <code
title="attr-font-color">color</code> attribute, its value is
expected to be parsed using the <span>rules for parsing a legacy
color value</span>, and if that does not return an error, the user
agent is expected to treat the attribute as a <span
title="presentational hints">presentational hint</span> setting the
element's 'color' property to the resulting color.</p>
<p>When a <code>font</code> element has a <code
title="attr-font-face">face</code> attribute, the user agent is
expected to treat the attribute as a <span title="presentational
hints">presentational hint</span> setting the element's
'font-family' property to the attribute's value.</p>
<!-- (Apparently only IE supports this?) (Note: if you add this
back, make sure to define which of 'size' vs 'pointsize' wins.)
<p>When a <code>font</code> element has a <code
title="attr-font-pointsize">pointsize</code> attribute, the user
agent is expected to parse that attribute's value using the
<span>rules for parsing non-negative integers</span>, and if this
doesn't generate an error, then the user agent is expected to use
the parsed value as a <em>point</em> length for a <span
title="presentational hints">presentational hint</span> for the
'font-size' property on the element.</p>
-->
<p>When a <code>font</code> element has a <code
title="attr-font-size">size</code> attribute, the user agent is
expected to use the following steps to treat the attribute as a
<span title="presentational hints">presentational hint</span>
setting the element's 'font-size' property:</p>
<ol>
<li><p>Let <var title="">input</var> be the attribute's
value.</p></li>
<li><p>Let <var title="">position</var> be a pointer into <var
title="">input</var>, initially pointing at the start of the
string.</p></li>
<li><p><span>Skip whitespace</span>.</p></li>
<li><p>If <var title="">position</var> is past the end of <var
title="">input</var>, there is no <span title="presentational
hints">presentational hint</span>. Abort these steps.</p></li>
<li><p>If the character at <var title="">position</var> is a U+002B
PLUS SIGN character (+), then let <var title="">mode</var> be
<i>relative-plus</i>, and advance <var title="">position</var> to
the next character. Otherwise, if the character at <var
title="">position</var> is a U+002D HYPHEN-MINUS character (-),
then let <var title="">mode</var> be <i>relative-minus</i>, and
advance <var title="">position</var> to the next
character. Otherwise, let <var title="">mode</var> be
<i>absolute</i>.</p></li>
<li><p><span>Collect a sequence of characters</span> in the range
U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and let the
resulting sequence be <var title="">digits</var>.</p></li>
<li><p>If <var title="">digits</var> is the empty string, there is
no <span title="presentational hints">presentational
hint</span>. Abort these steps.</p></li>
<li><p>Interpret <var title="">digits</var> as a base-ten
integer. Let <var title="">value</var> be the resulting
number.</p></li>
<li>
<!-- basefont support would go here, but we removed it -->
<p>If <var title="">mode</var> is <i>relative-plus</i>, then
increment <var title="">value</var> by 3. If <var
title="">mode</var> is <i>relative-minus</i>, then let <var
title="">value</var> be the result of subtracting <var
title="">value</var> from 3.</p>
</li>
<li><p>If <var title="">value</var> is greater than 7, let it be
7.</p></li>
<li><p>If <var title="">value</var> is less than 1, let it be
1.</p></li>
<li>
<p>Set 'font-size' to the keyword corresponding to the value of
<var title="">value</var> according to the following table:</p>
<table>
<thead>
<tr>
<th><var title="">value</var>
<th>'font-size' keyword
<th>Notes
<tbody>
<tr>
<td>1
<td>xx-small
<td>
<tr>
<td>2
<td>small
<td>
<tr>
<td>3
<td>medium
<td>
<tr>
<td>4
<td>large
<td>
<tr>
<td>5
<td>x-large
<td>
<tr>
<td>6
<td>xx-large
<td>
<tr>
<td>7
<td>x<!---->xx-large
<td><i>see below</i>
</table>
<p>The 'x<!---->xx-large' value is a non-CSS value used here to
indicate a font size one "step" larger than 'xx-large'.</p>
</li>
</ol>
</div>
<div class="impl">
<h4>Punctuation and decorations</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
:link, :visited, ins, u { text-decoration: underline; }
abbr[title], acronym[title] { text-decoration: dotted underline; }<!-- CSS3 http://dev.w3.org/csswg/css3-text/#text-decoration-style -->
del, s, strike { text-decoration: line-through; }
blink { text-decoration: blink; }
q:before { content: open-quote; }
q:after { content: close-quote; }
nobr { white-space: nowrap; }
listing, plaintext, pre, xmp { white-space: pre; }
ol { list-style-type: decimal; }
dir, menu, ul {
list-style-type: disc;
}
dir dl, dir menu, dir ul,
menu dl, menu menu, menu ul,
ol dl, ol menu, ol ul,
ul dl, ul menu, ul ul {
list-style-type: circle;
}
dir dir dl, dir dir menu, dir dir ul,
dir menu dl, dir menu menu, dir menu ul,
dir ol dl, dir ol menu, dir ol ul,
dir ul dl, dir ul menu, dir ul ul,
menu dir dl, menu dir menu, menu dir ul,
menu menu dl, menu menu menu, menu menu ul,
menu ol dl, menu ol menu, menu ol ul,
menu ul dl, menu ul menu, menu ul ul,
ol dir dl, ol dir menu, ol dir ul,
ol menu dl, ol menu menu, ol menu ul,
ol ol dl, ol ol menu, ol ol ul,
ol ul dl, ol ul menu, ol ul ul,
ul dir dl, ul dir menu, ul dir ul,
ul menu dl, ul menu menu, ul menu ul,
ul ol dl, ul ol menu, ul ol ul,
ul ul dl, ul ul menu, ul ul ul {
list-style-type: square;
}
table { border-style: outset; }
td, th { border-style: inset; }
[dir=ltr] { direction: ltr; unicode-bidi: embed; }
[dir=rtl] { direction: rtl; unicode-bidi: embed; }
bdo[dir=ltr], bdo[dir=rtl] { unicode-bidi: bidi-override; }</pre>
<p>In addition, rules setting the 'quotes' property appropriately
for the locales and languages understood by the user are expected to
be present.</p>
<hr>
<p>The following rules are also expected to apply, as
<span>presentational hints</span>:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
td[nowrap], th[nowrap] { white-space: nowrap; }
pre[wrap] { white-space: pre-wrap; }
br[clear=left] { clear: left; }
br[clear=right] { clear: right; }
br[clear=all], br[clear=both] { clear: both; }
ol[type=1], li[type=1] { list-style-type: decimal; }
ol[type=a], li[type=a] { list-style-type: lower-alpha; }
ol[type=A], li[type=A] { list-style-type: upper-alpha; }
ol[type=i], li[type=i] { list-style-type: lower-roman; }
ol[type=I], li[type=I] { list-style-type: upper-roman; }
ul[type=disc], li[type=disc] { list-style-type: disc; }
ul[type=circle], li[type=circle] { list-style-type: circle; }
ul[type=square], li[type=square] { list-style-type: square; }
table[rules=none], table[rules=groups], table[rules=rows],
table[rules=cols], table[rules=all] {
border-style: none;
border-collapse: collapse;
}
table[frame=void] { border-style: hidden hidden hidden hidden; }
table[frame=above] { border-style: solid hidden hidden hidden; }
table[frame=below] { border-style: hidden hidden solid hidden; }
table[frame=hsides] { border-style: solid hidden solid hidden; }
table[frame=lhs] { border-style: hidden hidden hidden solid; }
table[frame=rhs] { border-style: hidden solid hidden hidden; }
table[frame=vsides] { border-style: hidden solid hidden solid; }
table[frame=box],
table[frame=border] { border-style: solid solid solid solid; }
table[rules=none] > tr > td, table[rules=none] > tr > th,
table[rules=none] > thead > tr > td, table[rules=none] > thead > tr > th,
table[rules=none] > tbody > tr > td, table[rules=none] > tbody > tr > th,
table[rules=none] > tfoot > tr > td, table[rules=none] > tfoot > tr > th,
table[rules=groups] > tr > td, table[rules=groups] > tr > th,
table[rules=groups] > thead > tr > td, table[rules=groups] > thead > tr > th,
table[rules=groups] > tbody > tr > td, table[rules=groups] > tbody > tr > th,
table[rules=groups] > tfoot > tr > td, table[rules=groups] > tfoot > tr > th,
table[rules=rows] > tr > td, table[rules=rows] > tr > th,
table[rules=rows] > thead > tr > td, table[rules=rows] > thead > tr > th,
table[rules=rows] > tbody > tr > td, table[rules=rows] > tbody > tr > th,
table[rules=rows] > tfoot > tr > td, table[rules=rows] > tfoot > tr > th {
border-style: none;
}
table[rules=groups] > colgroup, table[rules=groups] > thead,
table[rules=groups] > tbody, table[rules=groups] > tfoot {
border-style: solid;
}
table[rules=rows] > tr, table[rules=rows] > thead > tr,
table[rules=rows] > tbody > tr, table[rules=rows] > tfoot > tr {
border-style: solid;
}
table[rules=cols] > tr > td, table[rules=cols] > tr > th,
table[rules=cols] > thead > tr > td, table[rules=cols] > thead > tr > th,
table[rules=cols] > tbody > tr > td, table[rules=cols] > tbody > tr > th,
table[rules=cols] > tfoot > tr > td, table[rules=cols] > tfoot > tr > th {
border-style: none solid none solid;
}
table[rules=all] > tr > td, table[rules=all] > tr > th,
table[rules=all] > thead > tr > td, table[rules=all] > thead > tr > th,
table[rules=all] > tbody > tr > td, table[rules=all] > tbody > tr > th,
table[rules=all] > tfoot > tr > td, table[rules=all] > tfoot > tr > th {
border-style: solid;
}
table[border] > tr > td, table[border] > tr > th,
table[border] > thead > tr > td, table[border] > thead > tr > th,
table[border] > tbody > tr > td, table[border] > tbody > tr > th,
table[border] > tfoot > tr > td, table[border] > tfoot > tr > th {
border-width: 1px;
}</pre>
<p>When rendering <code>li</code> elements, user agents are expected
to use the ordinal value of the <code>li</code> element to render
the counter in the list item marker.</p>
<p>The <code>table</code> element's <code
title="attr-table-border">border</code> attribute <span title="maps
to the pixel length property">maps to the pixel length
properties</span> 'border-top-width', 'border-right-width',
'border-bottom-width', 'border-left-width' on the element. If the
attribute is present but parsing the attribute's value using the
<span>rules for parsing non-negative integers</span> generates an
error, a default value of 1px is expected to be used for that
property instead.</p>
</div>
<div class="impl">
<h4>Resetting rules for inherited properties</h4>
<p>The following rules are also expected to be in play, resetting
certain properties to block inheritance by default.</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
table, input, select, option, optgroup, button, textarea, keygen {
text-indent: initial;
}</pre>
<!-- arguably, the form controls' 'text-indent' lines should be in
the sections below instead of here, but that would be far more
complicated than this -->
<p>In <span>quirks mode</span>, the following rules are also
expected to apply:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
table {
font-weight: initial;
font-style: initial;
font-variant: initial;
font-size: initial;
line-height: initial;
white-space: initial;
text-align: initial;
}
input { box-sizing: border-box; }</pre>
</div>
<div class="impl">
<h4>The <code>hr</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
hr { color: gray; border-style: inset; border-width: 1px; }</pre>
<p>The following rules are also expected to apply, as
<span>presentational hints</span>:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
hr[align=left] { margin-left: 0; margin-right: auto; }
hr[align=right] { margin-left: auto; margin-right: 0; }
hr[align=center] { margin-left: auto; margin-right: auto; }
hr[color], hr[noshade] { border-style: solid; }</pre>
<p>If an <code>hr</code> element has either a <code
title="attr-hr-color">color</code> attribute or a <code
title="attr-hr-noshade">noshade</code> attribute, and furthermore
also has a <code title="attr-hr-size">size</code> attribute, and
parsing that attribute's value using the <span>rules for parsing
non-negative integers</span> doesn't generate an error, then the
user agent is expected to use the parsed value divided by two as a
pixel length for <span>presentational hints</span> for the properties
'border-top-width', 'border-right-width', 'border-bottom-width', and
'border-left-width' on the element.</p>
<p>Otherwise, if an <code>hr</code> element has neither a <code
title="attr-hr-color">color</code> attribute nor a <code
title="attr-hr-noshade">noshade</code> attribute, but does have a
<code title="attr-hr-size">size</code> attribute, and parsing that
attribute's value using the <span>rules for parsing non-negative
integers</span> doesn't generate an error, then: if the parsed value
is one, then the user agent is expected to use the attribute as a
<span title="presentational hints">presentational hint</span>
setting the element's 'border-bottom-width' to 0; otherwise, if the
parsed value is greater than one, then the user agent is expected to
use the parsed value minus two as a pixel length for
<span>presentational hints</span> for the 'height' property on the
element.</p>
<p>The <code title="attr-hr-width">width</code> attribute on an
<code>hr</code> element <span>maps to the dimension property</span>
'width' on the element.</p>
<p>When an <code>hr</code> element has a <code
title="attr-hr-color">color</code> attribute, its value is expected
to be parsed using the <span>rules for parsing a legacy color
value</span>, and if that does not return an error, the user agent
is expected to treat the attribute as a <span title="presentational
hints">presentational hint</span> setting the element's 'color'
property to the resulting color.</p>
</div>
<div class="impl">
<h4>The <code>fieldset</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
fieldset {
margin-left: 2px; margin-right: 2px;
border: groove 2px ThreeDFace;
padding: 0.35em 0.625em 0.75em;
}</pre>
<p>The <code>fieldset</code> element is expected to establish a new
block formatting context.</p>
<p>The first <code>legend</code> element child of a
<code>fieldset</code> element, if any, is expected to be rendered
over the top border edge of the <code>fieldset</code> element. If
the <code>legend</code> element in question has an <code
title="attr-legend-align">align</code> attribute, and its value is
an <span>ASCII case-insensitive</span> match for one of the strings
in the first column of the following table, then the
<code>legend</code> is expected to be rendered horizontally aligned
over the border edge in the position given in the corresponding cell
on the same row in the second column. If the attribute is absent or
has a value that doesn't match any of the cases in the table, then
the position is expected to be on the right if the 'direction'
property on this element has a computed value of 'rtl', and on the
left otherwise.</p>
<table>
<thead>
<tr>
<th>Attribute value
<th>Alignment position
<tbody>
<tr>
<td><code title="">left</code>
<td>On the left
<tr>
<td><code title="">right</code>
<td>On the right
<tr>
<td><code title="">center</code>
<td>In the middle
</table>
</div>
<div class="impl">
<h3>Replaced elements</h3>
<h4>Embedded content</h4>
<p>The <code>embed</code>, <code>iframe</code>, and
<code>video</code> elements are expected to be treated as replaced
elements.</p>
<p>A <code>canvas</code> element that <span>represents</span>
<span>embedded content</span> is expected to be treated as a
replaced element. Other <code>canvas</code> elements are expected to
be treated as ordinary elements in the rendering model.</p>
<p>An <code>object</code> element that <span>represents</span> an
image, plugin, or <span>nested browsing context</span> is expected
to be treated as a replaced element. Other <code>object</code>
elements are expected to be treated as ordinary elements in the
rendering model.</p>
<p>An <code>applet</code> element that <span>represents</span> a
<span>plugin</span> is expected to be treated as a replaced
element. Other <code>applet</code> elements are expected to be
treated as ordinary elements in the rendering model.</p>
<p>The <code>audio</code> element, when it is <span title="expose a
user interface to the user">exposing a user interface</span>, is
expected to be treated as a replaced element about one line high, as
wide as is necessary to expose the user agent's user interface
features. When an <code>audio</code> element is not <span
title="expose a user interface to the user">exposing a user
interface</span>, the user agent is expected to hide it,
irrespective of CSS rules.</p>
<p>Whether a <code>video</code> element is <span title="expose a
user interface to the user">exposing a user interface</span> is not
expected to affect the size of the rendering; controls are expected
to be overlaid with the page content without causing any layout
changes, and are expected to disappear when the user does not need
them.</p>
<p>When a <code>video</code> element represents a poster frame or
frame of video, the poster frame or frame of video is expected to be
rendered at the largest size that maintains the aspect ratio of that
poster frame or frame of video without being taller or wider than
the <code>video</code> element itself, and is expected to be
centered in the <code>video</code> element.</p>
<p class="note">Resizing <code>video</code> and <code>canvas</code>
elements does not interrupt video playback or clear the canvas.</p>
<hr>
<p>The following CSS rules are expected to apply:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
iframe { border: 2px inset; }</pre>
</div>
<div class="impl">
<h4>Images</h4>
<p>When an <code>img</code> element or an <code>input</code> element
when its <code title="attr-input-type">type</code> attribute is in
the <span title="attr-input-type-image">Image Button</span> state
<span>represents</span> an image, it is expected to be treated as a
replaced element.</p>
<p>When an <code>img</code> element or an <code>input</code> element
when its <code title="attr-input-type">type</code> attribute is in
the <span title="attr-input-type-image">Image Button</span> state
does not <span title="represents">represent</span> an image, but the
element already has intrinsic dimensions (e.g. from the
<span>dimension attributes</span> or CSS rules), and either the user
agent has reason to believe that the image will become <i
title="img-available">available</i><!--input-img-available also-->
and be rendered in due course or the <code>Document</code> is in
<span>quirks mode</span>, the element is expected to be treated as a
replaced element whose content is the text that the element
represents, if any, optionally alongside an icon indicating that the
image is being obtained. For <code>input</code> elements, the text
is expected to appear button-like to indicate that the element is a
<span title="concept-button">button</span>.</p>
<p>When an <code>img</code> element <span>represents</span> some
text and the user agent does not expect this to change, the element
is expected to be treated as an inline element whose content is the
text, optionally with an icon indicating that an image is
missing.</p>
<p>When an <code>img</code> element <span>represents</span> nothing
and the user agent does not expect this to change, the element is
expected to not be rendered at all.</p>
<p>When an <code>img</code> element might be a key part of the
content, but neither the image nor any kind of alternative text is
available, and the user agent does not expect this to change, the
element is expected to be treated as an inline element whose content
is an icon indicating that an image is missing.</p> <!-- there's
also a should requirement for this case in the <img> section itself
-->
<p>When an <code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-image">Image Button</span> state does not
<span title="represents">represent</span> an image and the user
agent does not expect this to change, the element is expected to be
treated as a replaced element consisting of a button whose content
is the element's alternative text. The intrinsic dimensions of the
button are expected to be about one line in height and whatever
width is necessary to render the text on one line.</p>
<p>The icons mentioned above are expected to be relatively small so
as not to disrupt most text but be easily clickable. In a visual
environment, for instance, icons could be 16 pixels by 16 pixels
square, or 1em by 1em if the images are scalable. In an audio
environment, the icon could be a short bleep. The icons are intended
to indicate to the user that they can be used to get to whatever
options the UA provides for images, and, where appropriate, are
expected to provide access to the context menu that would have come
up if the user interacted with the actual image.</p>
<hr>
<p>The following CSS rules are expected to apply when the
<code>Document</code> is in <span>quirks mode</span>:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
img[align=left] { margin-right: 3px; }
img[align=right] { margin-left: 3px; }</pre>
</div>
<div class="impl">
<h4>Attributes for embedded content and images</h4>
<p>The following CSS rules are expected to apply as
<span>presentational hints</span>:</p>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
iframe[frameborder=0], iframe[frameborder=no] { border: none; }
applet[align=left], embed[align=left], iframe[align=left],
img[align=left], input[type=image][align=left], object[align=left] {
float: left;
}
applet[align=right], embed[align=right], iframe[align=right],
img[align=right], input[type=image][align=right], object[align=right] {
float: right;
}
applet[align=top], embed[align=top], iframe[align=top],
img[align=top], input[type=image][align=top], object[align=top] {
vertical-align: top;
}
applet[align=bottom], embed[align=bottom], iframe[align=bottom],
img[align=bottom], input[type=image][align=bottom], object[align=bottom],
applet[align=baseline], embed[align=baseline], iframe[align=baseline],
img[align=baseline], input[type=image][align=baseline], object[align=baseline] {
vertical-align: baseline;
}
applet[align=texttop], embed[align=texttop], iframe[align=texttop],
img[align=texttop], input[type=image][align=texttop], object[align=texttop] {
vertical-align: text-top;
}
applet[align=absmiddle], embed[align=absmiddle], iframe[align=absmiddle],
img[align=absmiddle], input[type=image][align=absmiddle], object[align=absmiddle],
applet[align=abscenter], embed[align=abscenter], iframe[align=abscenter],
img[align=abscenter], input[type=image][align=abscenter], object[align=abscenter] {
vertical-align: middle;
}
applet[align=bottom], embed[align=bottom], iframe[align=bottom],
img[align=bottom], input[type=image][align=bottom],
object[align=bottom] {
vertical-align: bottom;
}</pre>
<p>When an <code>applet</code>, <code>embed</code>,
<code>iframe</code>, <code>img</code>, or <code>object</code>
element, or an <code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-image">Image Button</span> state, has an
<code title="attr-dim-align">align</code> attribute whose value is
an <span>ASCII case-insensitive</span> match for the string "<code
title="">center</code>" or the string "<code
title="">middle</code>", the user agent is expected to act as if the
element's 'vertical-align' property was set to a value that aligns
the vertical middle of the element with the parent element's
baseline.</p>
<p>The <code title="attr-dim-hspace">hspace</code> attribute of
<code>applet</code>, <code>embed</code>, <code>iframe</code>,
<code>img</code>, or <code>object</code> elements, and
<code>input</code> elements with a <code
title="attr-input-type">type</code> attribute in the <span
title="attr-input-type-image">Image Button</span> state, <span
title="maps to the dimension property">maps to the dimension
properties</span> 'margin-left' and 'margin-right' on the
element.</p>
<p>The <code title="attr-dim-vspace">vspace</code> attribute of
<code>applet</code>, <code>embed</code>, <code>iframe</code>,
<code>img</code>, or <code>object</code> elements, and
<code>input</code> elements with a <code
title="attr-input-type">type</code> attribute in the <span
title="attr-input-type-image">Image Button</span> state, <span
title="maps to the dimension property">maps to the dimension
properties</span> 'margin-top' and 'margin-bottom' on the
element.</p>
<p>When an <code>img</code> element, <code>object</code> element, or
<code>input</code> element with a <code
title="attr-input-type">type</code> attribute in the <span
title="attr-input-type-image">Image Button</span> state is contained
within a <span>hyperlink</span> and has a <code
title="attr-dim-border">border</code> attribute whose value, when
parsed using the <span>rules for parsing non-negative
integers</span>, is found to be a number greater than zero, the user
agent is expected to use the parsed value for eight
<span>presentational hints</span>: four setting the parsed value as
a pixel length for the element's 'border-top-width',
'border-right-width', 'border-bottom-width', and 'border-left-width'
properties, and four setting the element's 'border-top-style',
'border-right-style', 'border-bottom-style', and 'border-left-style'
properties to the value 'solid'.</p>
<p id="dimRendering">The <code title="attr-dim-width">width</code>
and <code title="attr-dim-height">height</code> attributes on
<code>applet</code>, <code>embed</code>, <code>iframe</code>,
<code>img</code>, <code>object</code> or <code>video</code>
elements, and <code>input</code> elements with a <code
title="attr-input-type">type</code> attribute in the <span
title="attr-input-type-image">Image Button</span> state, <span
title="maps to the dimension property">map to the dimension
properties</span> 'width' and 'height' on the element
respectively.</p>
</div>
<div class="impl">
<h4>Image maps</h4>
<p>Shapes on an <span>image map</span> are expected to act, for the
purpose of the CSS cascade, as elements independent of the original
<code>area</code> element that happen to match the same style rules
but inherit from the <code>img</code> or <code>object</code>
element.</p>
<p>For the purposes of the rendering, only the 'cursor' property is
expected to have any effect on the shape.</p>
<p class="example">Thus, for example, if an <code>area</code>
element has a <code title="attr-style">style</code> attribute that
sets the 'cursor' property to 'help', then when the user designates
that shape, the cursor would change to a Help cursor.</p>
<p class="example">Similarly, if an <code>area</code> element had a
CSS rule that set its 'cursor' property to 'inherit' (or if no rule
setting the 'cursor' property matched the element at all), the
shape's cursor would be inherited from the <code>img</code> or
<code>object</code> element of the <span>image map</span>, not from
the parent of the <code>area</code> element.</p>
</div>
<div class="impl">
<h4>Toolbars</h4>
<p>When a <code>menu</code> element's <code
title="attr-menu-type">type</code> attribute is in the <span
title="toolbar state">toolbar</span> state, the element is
expected to be treated as a replaced element with a height about two
lines high and a width derived from the contents of the element.</p>
<p>The element is expected to have, by default, the appearance of a
toolbar on the user agent's platform. It is expected to contain the
menu that is <span title="building menus and toolbars">built</span>
from the element.</p>
</div>
<div class="impl">
<h3>Bindings</h3>
<h4>Introduction</h4>
<p>A number of elements have their rendering defined in terms of the
'binding' property. <a href="#refsBECSS">[BECSS]</a></p>
<p>The CSS snippets below set the 'binding' property to a
user-agent-defined value, represented below by keywords like <code
title=""><i title="">button</i></code>. The rules then described for
these bindings are only expected to apply if the element's 'binding'
property has not been overridden (e.g. by the author) to have
another value.</p>
<p>Exactly how the bindings are implemented is not specified by this
specification. User agents are encouraged to make their bindings set
the 'appearance' CSS property appropriately to achieve
platform-native appearances for widgets, and are expected to
implement any relevant animations, etc, that are appropriate for the
platform. <a href="#refsCSSUI">[CSSUI]</a></p>
</div>
<div class="impl">
<h4>The <code>button</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
button { binding: <i title="">button</i>; }</pre>
<p>When the <i title="">button</i> binding applies to a
<code>button</code> element, the element is expected to render as an
'inline-block' box rendered as a button whose contents are the
contents of the element.</p>
</div>
<!--v2DATAGRID
<div class="impl">
<h4>The <code>datagrid</code> element</h4>
This section will probably include details on how to render DATAGRID
(including <span id="datagridPseudos">its pseudo-elements</span>),
drag-and-drop, etc, in a visual medium, in concert with
CSS. Implementation experience is desired before this section is
filled in.
</div>
-->
<div class="impl">
<h4>The <code>details</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
details { binding: <i title="">details</i>; }</pre>
<p>When the <i title="">details</i> binding applies to a
<code>details</code> element, the element is expected to render as a
'block' box with its 'padding-left' property set to '40px'. The
element's shadow tree is expected to take the element's first child
<code>dt</code> element, if any, and place it in a first 'block' box
container, and then take the element's first child <code>dd</code>
element, if any, and place it in a second 'block' box container,
ignoring all the other children of the element.</p>
<p>The first container is expected to contain at least one line box,
and that line box is expected to contain a disclosure widget
(typically a triangle), horizontally positioned within the left
padding of the <code>details</code> element. That widget is expected
to allow the user to request that the details be shown or
hidden.</p>
<p>The second container is expected to have its 'overflow' property
set to 'hidden'. When the <code>details</code> element does not have
an <code title="attr-details-open">open</code> attribute, this
second container is expected to be removed from the rendering.</p>
<!-- http://mail.gnome.org/archives/usability/2006-June/msg00015.html -->
</div>
<div class="impl">
<h4>The <code>input</code> element as a text entry widget</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
input { binding: <i title="">input-textfield</i>; }
input[type=password] { binding: <i title="">input-password</i>; }
/* later rules override this for other values of type="" */</pre>
<p>When the <i title="">input-textfield</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-text">Text</span>, <span
title="attr-input-type-search">Search</span>, <span
title="attr-input-type-tel">Telephone</span>, <span
title="attr-input-type-url">URL</span>, or <span
title="attr-input-type-email">E-mail</span> state, the element is
expected to render as an 'inline-block' box rendered as a text
field.</p>
<p>When the <i title="">input-password</i> binding applies, to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-password">Password</span> state, the element
is expected to render as an 'inline-block' box rendered as a text
field whose contents are obscured.</p>
<p>If an <code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in one of the above
states has a <code title="attr-input-size">size</code> attribute,
and parsing that attribute's value using the <span>rules for parsing
non-negative integers</span> doesn't generate an error, then the
user agent is expected to use the attribute as a <span
title="presentational hints">presentational hint</span> for the
'width' property on the element, with the value obtained from
applying the <span>converting a character width to pixels</span>
algorithm to the value of the attribute.</p>
<p>If an <code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in one of the above
states does <em>not</em> have a <code
title="attr-input-size">size</code> attribute, then the user agent
is expected to act as if it had a user-agent-level style sheet rule
setting the 'width' property on the element to the value obtained
from applying the <span>converting a character width to
pixels</span> algorithm to the number 20.</p>
<p>The <dfn>converting a character width to pixels</dfn> algorithm
returns <span title="">(<var title="">size</var>-1)×<var
title="">avg</var> + <var title="">max</var></span>, where
<var title="">size</var> is the character width to convert, <var
title="">avg</var> is the average character width of the primary
font for the element for which the algorithm is being run, in
pixels, and <var title="">max</var> is the maximum character width
of that same font, also in pixels. (The element's 'letter-spacing'
property does not affect the result.)</p>
</div>
<div class="impl">
<h4>The <code>input</code> element as domain-specific widgets</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
input[type=datetime] { binding: <i title="">input-datetime</i>; }
input[type=date] { binding: <i title="">input-date</i>; }
input[type=month] { binding: <i title="">input-month</i>; }
input[type=week] { binding: <i title="">input-week</i>; }
input[type=time] { binding: <i title="">input-time</i>; }
input[type=datetime-local] { binding: <i title="">input-datetime-local</i>; }
input[type=number] { binding: <i title="">input-number</i>; }</pre>
<p>When the <i title="">input-datetime</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-datetime">Date and Time</span> state, the
element is expected to render as an 'inline-block' box depicting a
Date and Time control.</p>
<p>When the <i title="">input-date</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-date">Date</span> state, the element is
expected to render as an 'inline-block' box depicting a Date
control.</p>
<p>When the <i title="">input-month</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-month">Month</span> state, the element is
expected to render as an 'inline-block' box depicting a Month
control.</p>
<p>When the <i title="">input-week</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-week">Week</span> state, the element is
expected to render as an 'inline-block' box depicting a Week
control.</p>
<p>When the <i title="">input-time</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-time">Time</span> state, the element is
expected to render as an 'inline-block' box depicting a Time
control.</p>
<p>When the <i title="">input-datetime-local</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-datetime-local">Local Date and Time</span>
state, the element is expected to render as an 'inline-block' box
depicting a Local Date and Time control.</p>
<p>When the <i title="">input-number</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-number">Number</span> state, the element is
expected to render as an 'inline-block' box depicting a Number
control.</p>
<p>These controls are all expected to be about one line high, and
about as wide as necessary to show the widest possible value.</p>
</div>
<div class="impl">
<h4>The <code>input</code> element as a range control</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
input[type=range] { binding: <i title="">input-range</i>; }</pre>
<p>When the <i title="">input-range</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-range">Range</span> state, the element is
expected to render as an 'inline-block' box depicting a slider
control.</p>
<p>When the control is wider than it is tall (or square), the
control is expected to be a horizontal slider, with the lowest value
on the right if the 'direction' property on this element has a
computed value of 'rtl', and on the left otherwise. When the control
is taller than it is wide, it is expected to be a vertical slider,
with the lowest value on the bottom.</p>
<p>Predefined suggested values (provided by the <code
title="attr-input-list">list</code> attribute) are expected to be
shown as tick marks on the slider, which the slider can snap to.</p>
</div>
<div class="impl">
<h4>The <code>input</code> element as a color well</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
input[type=color] { binding: <i title="">input-color</i>; }</pre>
<p>When the <i title="">input-color</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-color">Color</span> state, the element is
expected to render as an 'inline-block' box depicting a color well,
which, when activated, provides the user with a color picker (e.g. a
color wheel or color palette) from which the color can be
changed.</p>
<p>Predefined suggested values (provided by the <code
title="attr-input-list">list</code> attribute) are expected to be
shown in the color picker interface, not on the color well
itself.</p>
</div>
<div class="impl">
<h4>The <code>input</code> element as a check box and radio button widgets</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
input[type=checkbox] { binding: <i title="">input-checkbox</i>; }
input[type=radio] { binding: <i title="">input-radio</i>; }</pre>
<p>When the <i title="">input-checkbox</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-checkbox">Checkbox</span> state, the element
is expected to render as an 'inline-block' box containing a single
check box control, with no label.</p>
<p>When the <i title="">input-radio</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-radio">Radio Button</span> state, the element
is expected to render as an 'inline-block' box containing a single
radio button control, with no label.</p>
</div>
<div class="impl">
<h4>The <code>input</code> element as a file upload control</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
input[type=file] { binding: <i title="">input-file</i>; }</pre>
<p>When the <i title="">input-file</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-file">File Upload</span> state, the element
is expected to render as an 'inline-block' box containing a span of
text giving the filename(s) of the <span
title="concept-input-type-file-selected">selected files</span>, if
any, followed by a button that, when activated, provides the user
with a file picker from which the selection can be changed.</p>
</div>
<div class="impl">
<h4>The <code>input</code> element as a button</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
input[type=submit], input[type=reset], input[type=button] {
binding: <i title="">input-button</i>;
}</pre>
<p>When the <i title="">input-button</i> binding applies to an
<code>input</code> element whose <code
title="attr-input-type">type</code> attribute is in the <span
title="attr-input-type-submit">Submit Button</span>, <span
title="attr-input-type-reset">Reset Button</span>, or <span
title="attr-input-type-button">Button</span> state, the element is
expected to render as an 'inline-block' box rendered as a button,
about one line high, containing the contents of the element's <code
title="attr-input-value">value</code> attribute, if any, or text
derived from the element's <code title="attr-input-type">type</code>
attribute in a user-agent-defined (and probably locale-specific)
fashion, if not.</p>
</div>
<div class="impl">
<h4>The <code>marquee</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
marquee {
binding: <i title="">marquee</i>;
}</pre>
<p>When the <i title="">marquee</i> binding applies to a
<code>marquee</code> element, while the element is <span
title="concept-marquee-on">turned on</span>, the element is expected
to render in an animated fashion according to its attributes as
follows:</p>
<dl>
<dt>If the element's <code
title="attr-marquee-behavior">behavior</code> attribute is in the
<span title="attr-marquee-behavior-scroll">scroll</span> state</dt>
<dd>
<p>Slide the contents of the element in the direction described by
the <code title="attr-marquee-direction">direction</code>
attribute as defined below, such that it begins off the start side
of the <code>marquee</code>, and ends flush with the inner end
side.</p>
<p class="example">For example, if the <code
title="attr-marquee-direction">direction</code> attribute is <span
title="attr-marquee-direction-left">left</span> (the default),
then the contents would start such that their left edge are off
the side of the right edge of the <code>marquee</code>'s content
area, and the contents would then slide up to the point where the
left edge of the contents are flush with the left inner edge of
the <code>marquee</code>'s content area.</p>
<p>Once the animation has ended, the user agent is expected to
<span>increment the marquee current loop index</span>. If the
element is still <span title="concept-marquee-on">turned on</span>
after this, then the user agent is expected to restart the
animation.</p>
</dd>
<dt>If the element's <code
title="attr-marquee-behavior">behavior</code> attribute is in the
<span title="attr-marquee-behavior-slide">slide</span> state</dt>
<dd>
<p>Slide the contents of the element in the direction described by
the <code title="attr-marquee-direction">direction</code>
attribute as defined below, such that it begins off the start side
of the <code>marquee</code>, and ends off the end side of the
<code>marquee</code>.</p>
<p class="example">For example, if the <code
title="attr-marquee-direction">direction</code> attribute is <span
title="attr-marquee-direction-left">left</span> (the default),
then the contents would start such that their left edge are off
the side of the right edge of the <code>marquee</code>'s content
area, and the contents would then slide up to the point where the
<em>right</em> edge of the contents are flush with the left inner
edge of the <code>marquee</code>'s content area.</p>
<p>Once the animation has ended, the user agent is expected to
<span>increment the marquee current loop index</span>. If the
element is still <span title="concept-marquee-on">turned on</span>
after this, then the user agent is expected to restart the
animation.</p>
</dd>
<dt>If the element's <code
title="attr-marquee-behavior">behavior</code> attribute is in the
<span title="attr-marquee-behavior-alternate">alternate</span>
state</dt>
<dd>
<p>When the <span>marquee current loop index</span> is even (or
zero), slide the contents of the element in the direction
described by the <code
title="attr-marquee-direction">direction</code> attribute as
defined below, such that it begins flush with the start side of
the <code>marquee</code>, and ends flush with the end side of the
<code>marquee</code>.</p>
<p>When the <span>marquee current loop index</span> is odd, slide
the contents of the element in the opposite direction than that
described by the <code
title="attr-marquee-direction">direction</code> attribute as
defined below, such that it begins flush with the end side of the
<code>marquee</code>, and ends flush with the start side of the
<code>marquee</code>.</p>
<p class="example">For example, if the <code
title="attr-marquee-direction">direction</code> attribute is <span
title="attr-marquee-direction-left">left</span> (the default),
then the contents would with their right edge flush with the right
inner edge of the <code>marquee</code>'s content area, and the
contents would then slide up to the point where the <em>left</em>
edge of the contents are flush with the left inner edge of the
<code>marquee</code>'s content area.</p>
<p>Once the animation has ended, the user agent is expected to
<span>increment the marquee current loop index</span>. If the
element is still <span title="concept-marquee-on">turned on</span>
after this, then the user agent is expected to continue the
animation.</p>
</dd>
</dl>
<p>The <code title="attr-marquee-direction">direction</code>
attribute has the meanings described in the following table:</p>
<table>
<thead>
<tr>
<th><code title="attr-marquee-direction">direction</code> attribute state
<th>Direction of animation
<th>Start edge
<th>End edge
<th>Opposite direction
<tbody>
<tr>
<td><span title="attr-marquee-direction-left">left</span>
<td>← Right to left
<td>Right
<td>Left
<td>→ Left to Right
<tr>
<td><span title="attr-marquee-direction-right">right</span>
<td>→ Left to Right
<td>Left
<td>Right
<td>← Right to left
<tr>
<td><span title="attr-marquee-direction-up">up</span>
<td>↑ Up (Bottom to Top)
<td>Bottom
<td>Top
<td>↓ Down (Top to Bottom)
<tr>
<td><span title="attr-marquee-direction-down">down</span>
<td>↓ Down (Top to Bottom)
<td>Top
<td>Bottom
<td>↑ Up (Bottom to Top)
</table>
<p>In any case, the animation should proceed such that there is a
delay given by the <span>marquee scroll interval</span> between each
frame, and such that the content moves at most the distance given by
the <span>marquee scroll distance</span> with each frame.</p>
<p>When a <code>marquee</code> element has a <code
title="attr-bgcolor">bgcolor</code> attribute set, the value is
expected to be parsed using the <span>rules for parsing a legacy
color value</span>, and if that does not return an error, the user
agent is expected to treat the attribute as a <span
title="presentational hints">presentational hint</span> setting the
element's 'background-color' property to the resulting color.</p>
<p>The <code title="attr-marquee-width">width</code> and <code
title="attr-marquee-height">height</code> attributes on a
<code>marquee</code> element <span title="maps to the dimenson
property">map to the dimension properties</span> 'width' and
'height' on the element respectively.</p>
<p>The intrinsic height of a <code>marquee</code> element with its
<code title="attr-marquee-direction">direction</code> attribute in
the <span title="attr-marquee-direction-up">up</span> or <span
title="attr-marquee-direction-down">down</span> states is 200 CSS
pixels.</p>
<p>The <code title="attr-marquee-vspace">vspace</code> attribute of
a <code>marquee</code> element <span title="maps to the dimension
property">maps to the dimension properties</span> 'margin-top' and
'margin-bottom' on the element. The <code
title="attr-marquee-hspace">hspace</code> attribute of a
<code>marquee</code> element <span title="maps to the dimension
property">maps to the dimension properties</span> 'margin-left' and
'margin-right' on the element.</p>
<p>The 'overflow' property on the <code>marquee</code> element is
expected to be ignored; overflow is expected to always be
hidden.</p>
</div>
<div class="impl">
<h4>The <code>meter</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
meter {
binding: <i title="">meter</i>;
}</pre>
<p>When the <i title="">meter</i> binding applies to a
<code>meter</code> element, the element is expected to render as an
'inline-block' box with a 'height' of '1em' and a 'width' of '5em',
a 'vertical-align' of '-0.2em', and with its contents depicting a
gauge.</p>
<p>When the element is wider than it is tall (or square), the
depiction is expected to be of a horizontal gauge, with the minimum
value on the right if the 'direction' property on this element has a
computed value of 'rtl', and on the left otherwise. When the element
is taller than it is wide, it is expected to depict a vertical
gauge, with the minimum value on the bottom.</p>
<p>User agents are expected to use a presentation consistent with
platform conventions for gauges, if any.</p>
<p class="note">Requirements for what must be depicted in the gauge
are included in the definition of the <code>meter</code>
element.</p>
</div>
<div class="impl">
<h4>The <code>progress</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
progress {
binding: <i title="">progress</i>;
}</pre>
<p>When the <i title="">progress</i> binding applies to a
<code>progress</code> element, the element is expected to render as
an 'inline-block' box with a 'height' of '1em' and a 'width' of
'10em', a 'vertical-align' of '-0.2em', and with its contents
depicting a horizontal progress bar, with the start on the right and
the end on the left if the 'direction' property on this element has
a computed value of 'rtl', and with the start on the left and the
end on the right otherwise.</p>
<p>User agents are expected to use a presentation consistent with
platform conventions for progress bars. In particular, user agents
are expected to use different presentations for determinate and
indeterminate progress bars. User agents are also expected to vary
the presentation based on the dimensions of the element.</p>
<p class="example">For example, on some platforms for showing
indeterminate progress there is an asynchronous progress indicator
with square dimensions, which could be used when the element is
square, and an indeterminate progress bar, which could be used when
the element is wide.</p>
<p class="note">Requirements for how to determine if the progress
bar is determinate or indeterminate, and what progress a determinate
progress bar is to show, are included in the definition of the
<code>progress</code> element.</p>
</div>
<div class="impl">
<h4>The <code>select</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
select {
binding: <i title="">select</i>;
}</pre>
<p>When the <i title="">select</i> binding applies to a
<code>select</code> element whose <code
title="attr-select-multiple">multiple</code> attribute is present,
the element is expected to render as a multi-select list box.</p>
<p>When the <i title="">select</i> binding applies to a
<code>select</code> element whose <code
title="attr-select-multiple">multiple</code> attribute is absent,
and the element's <code title="attr-select-size">size</code>
attribute <span title="rules for parsing non-negative
integers">specifies</span> a value greater than 1, the element is
expected to render as a single-select list box.</p>
<p>When the element renders as a list box, it is expected to render
as an 'inline-block' box whose 'height' is the height necessary to
contain as many rows for items as <span title="rules for parsing
non-negative integers">specified</span> by the element's <code
title="attr-select-size">size</code> attribute, or four rows if the
attribute is absent, and whose 'width' is the <span>width of the
<code>select</code>'s labels</span> plus the width of a
scrollbar.</p>
<p>When the <i title="">select</i> binding applies to a
<code>select</code> element whose <code
title="attr-select-multiple">multiple</code> attribute is absent,
and the element's <code title="attr-select-size">size</code>
attribute is either absent or <span title="rules for parsing
non-negative integers">specifies</span> either no value (an error),
or a value less than or equal to 1, the element is expected to
render as a one-line drop down box whose width is the <span>width of
the <code>select</code>'s labels</span>.</p>
<p>In either case (list box or drop-down box), the element's items
are expected to be the element's <span
title="concept-select-option-list">list of options</span>, with the
element's <code>optgroup</code> element children providing headers
for groups of options where applicable.</p>
<p>The <dfn>width of the <code>select</code>'s labels</dfn> is the
wider of the width necessary to render the widest
<code>optgroup</code>, and the width necessary to render the widest
<code>option</code> element in the element's <span
title="concept-select-option-list">list of options</span> (including
its indent, if any).</p>
<p>An <code>optgroup</code> element is expected to be rendered by
displaying the element's <code
title="attr-optgroup-label">label</code> attribute.</p>
<p>An <code>option</code> element is expected to be rendered by
displaying the element's <code
title="concept-option-label">label</code>, indented under its
<code>optgroup</code> element if it has one.</p>
</div>
<div class="impl">
<h4>The <code>textarea</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
textarea { binding: <i title="">textarea</i>; }</pre>
<p>When the <i title="">textarea</i> binding applies to a
<code>textarea</code> element, the element is expected to render as
an 'inline-block' box rendered as a multiline text field.</p>
<p>If the element has a <code title="attr-textarea-cols">cols</code>
attribute, and parsing that attribute's value using the <span>rules
for parsing non-negative integers</span> doesn't generate an error,
then the user agent is expected to use the attribute as a <span
title="presentational hints">presentational hint</span> for the
'width' property on the element, with the value being the
<span>textarea effective width</span> (as defined below). Otherwise,
the user agent is expected to act as if it had a user-agent-level
style sheet rule setting the 'width' property on the element to the
<span>textarea effective width</span>.</p>
<p>The <dfn>textarea effective width</dfn> of a
<code>textarea</code> element is <span><var
title="">size</var>×<var title="">avg</var> + <var
title="">sbw</var></span>, where <var title="">size</var> is the
element's <span title="attr-textarea-cols-value">character
width</span>, <var title="">avg</var> is the average character width
of the primary font of the element, in CSS pixels, and <var
title="">sbw</var> is the width of a scroll bar, in CSS pixels. (The
element's 'letter-spacing' property does not affect the result.)</p>
<p>If the element has a <code title="attr-textarea-rows">rows</code>
attribute, and parsing that attribute's value using the <span>rules
for parsing non-negative integers</span> doesn't generate an error,
then the user agent is expected to use the attribute as a <span
title="presentational hints">presentational hint</span> for the
'height' property on the element, with the value being the
<span>textarea effective height</span> (as defined
below). Otherwise, the user agent is expected to act as if it had a
user-agent-level style sheet rule setting the 'height' property on
the element to the <span>textarea effective height</span>.</p>
<p>The <dfn>textarea effective height</dfn> of a
<code>textarea</code> element is the height in CSS pixels of the
number of lines specified the element's <span
title="attr-textarea-rows-value">character height</span>, plus the
height of a scrollbar in CSS pixels.</p>
<p>For historical reasons, if the element has a <code
title="attr-textarea-wrap">wrap</code> attribute whose value is an
<span>ASCII case-insensitive</span> match for the string "<code
title="attr-textarea-wrap-off">off</code>", then the user agent is
expected to not wrap the rendered value; otherwise, the value of the
control is expected to be wrapped to the width of the control.</p>
</div>
<div class="impl">
<h4>The <code>keygen</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
keygen { binding: <i title="">keygen</i>; }</pre>
<p>When the <i title="">keygen</i> binding applies to a
<code>keygen</code> element, the element is expected to render as an
'inline-block' box containing a user interface to configure the key
pair to be generated.</p>
</div>
<div class="impl">
<h4>The <code>time</code> element</h4>
<pre class="css">@namespace url(http://www.w3.org/1999/xhtml);
time:empty { binding: <i title="">time</i>; }</pre>
<p>When the <i title="">time</i> binding applies to a
<code>time</code> element, the element is expected to render as if
it contained text conveying the <span
title="concept-time-date">date</span> (if known), <span
title="concept-time-time">time</span> (if known), and <span
title="concept-time-timezone">time-zone offset</span> (if known)
represented by the element, in the fashion most convenient for the
user.</p>
</div>
<div class="impl">
<h3>Frames and framesets</h3>
<p>When an <code>html</code> element's second child element is a
<code>frameset</code> element, the user agent is expected to render
the <code>frameset</code> element as described below across the
surface of the <span>view</span>, instead of applying the usual CSS
rendering rules.</p>
<p>When rendering a <code>frameset</code> on a surface, the user
agent is expected to use the following layout algorithm:</p>
<ol>
<li>
<p>The <var title="">cols</var> and <var title="">rows</var>
variables are lists of zero or more pairs consisting of a number
and a unit, the unit being one of <i>percentage</i>,
<i>relative</i>, and <i>absolute</i>.</p>
<p>Use the <span>rules for parsing a list of dimensions</span> to
parse the value of the element's <code
title="attr-frameset-cols">cols</code> attribute, if there is
one. Let <var title="">cols</var> be the result, or an empty list
if there is no such attribute.</p>
<p>Use the <span>rules for parsing a list of dimensions</span> to
parse the value of the element's <code
title="attr-frameset-rows">rows</code> attribute, if there is
one. Let <var title="">rows</var> be the result, or an empty list
if there is no such attribute.</p>
</li>
<li>
<p>For any of the entries in <var title="">cols</var> or <var
title="">rows</var> that have the number zero and the unit
<i>relative</i>, change the entry's number to one.</p>
</li>
<li>
<p>If <var title="">cols</var> has no entries, then add a single
entry consisting of the value 1 and the unit <i>relative</i> to
<var title="">cols</var>.</p>
<p>If <var title="">rows</var> has no entries, then add a single
entry consisting of the value 1 and the unit <i>relative</i> to
<var title="">rows</var>.</p>
</li>
<li>
<p>Invoke the algorithm defined below to <span>convert a list of
dimensions to a list of pixel values</span> using <var
title="">cols</var> as the input list, and the width of the
surface that the <code>frameset</code> is being rendered into, in
CSS pixels, as the input dimension. Let <var title="">sized
cols</var> be the resulting list.</p>
<p>Invoke the algorithm defined below to <span>convert a list of
dimensions to a list of pixel values</span> using <var
title="">rows</var> as the input list, and the height of the
surface that the <code>frameset</code> is being rendered into, in
CSS pixels, as the input dimension. Let <var title="">sized
rows</var> be the resulting list.</p>
</li>
<li>
<p>Split the surface into a grid of <span title=""><var
title="">w</var>×<var title="">h</var></span> rectangles,
where <var title="">w</var> is the number of entries in <var
title="">sized cols</var> and <var title="">h</var> is the number
of entries in <var title="">sized rows</var>.</p>
<p>Size the columns so that each column in the grid is as many CSS
pixels wide as the corresponding entry in the <var title="">sized
cols</var> list.</p>
<p>Size the rows so that each row in the grid is as many CSS
pixels high as the corresponding entry in the <var title="">sized
rows</var> list.</p>
</li>
<li>
<p>Let <var title="">children</var> be the list of
<code>frame</code> and <code>frameset</code> elements that are
children of the <code>frameset</code> element for which the
algorithm was invoked.</p>
</li>
<li>
<p>For each row of the grid of rectangles created in the previous
step, from top to bottom, run these substeps:</p>
<ol>
<li>
<p>For each rectangle in the row, from left to right, run these
substeps:</p>
<ol>
<li>
<p>If there are any elements left in <var
title="">children</var>, take the first element in the list,
and assign it to the rectangle.</p>
<p>If this is a <code>frameset</code> element, then recurse
the entire <code>frameset</code> layout algorithm for that
<code>frameset</code> element, with the rectangle as the
surface.</p>
<p>Otherwise, it is a <code>frame</code> element; create a
<span>nested browsing context</span> sized to fit the
rectangle.</p>
</li>
<li>
<p>If there are any elements left in <var
title="">children</var>, remove the first element from <var
title="">children</var>.</p>
</ol>
</li>
</ol>
</li>
<li>
<p>If the <code>frameset</code> element <span>has a border</span>,
draw an outer set of borders around the rectangles, using the
element's <span>frame border color</span>.</p>
<p>For each rectangle, if there is an element assigned to that
rectangle, and that element <span>has a border</span>, draw an
inner set of borders around that rectangle, using the
element's <span>frame border color</span>.</p>
<p>For each (visible) border that does not abut a rectangle that
is assigned a <code>frame</code> element with a <code
title="attr-frame-noresize">noresize</code> attribute (including
rectangles in further nested <code>frameset</code> elements), the
user agent is expected to allow the user to move the border,
resizing the rectangles within, keeping the proportions of any
nested <code>frameset</code> grids.</p>
<p>A <code>frameset</code> or <code>frame</code> element <dfn>has
a border</dfn> if the following algorithm returns true:</p>
<ol>
<li><p>If the element has a <code
title="attr-frames-frameborder">frameborder</code> attribute
whose value is not the empty string and whose first character is
either a U+0031 DIGIT ONE (1) character, a U+0079 LATIN SMALL
LETTER Y character (y), or a U+0059 LATIN CAPITAL LETTER Y
character (Y), then return true.</p></li>
<li><p>Otherwise, if the element has a <code
title="attr-frames-frameborder">frameborder</code> attribute,
return false.</p></li>
<li><p>Otherwise, if the element has a parent element that is a
<code>frameset</code> element, then return true if <em>that</em>
element <span>has a border</span>, and false if it does
not.</p></li>
<li><p>Otherwise, return true.</p></li>
</ol>
<p>The <dfn>frame border color</dfn> of a <code>frameset</code> or
<code>frame</code> element is the color obtained from the
following algorithm:</p>
<ol>
<li><p>If the element has a <code
title="attr-frames-bordercolor">bordercolor</code> attribute, and
applying the <span>rules for parsing a legacy color value</span>
to that attribute's value does not result in an error, then
return the color so obtained.</p></li>
<li><p>Otherwise, if the element has a parent element that is a
<code>frameset</code> element, then the <span>frame border
color</span> of that element.</p>
<li><p>Otherwise, return gray.</p></li>
</ol>
</li>
</ol>
<p>The algorithm to <dfn>convert a list of dimensions to a list of
pixel values</dfn> consists of the following steps:</p>
<ol>
<li>
<p>Let <var title="">input list</var> be the list of numbers and
units passed to the algorithm.</p>
<p>Let <var title="">output list</var> be a list of numbers the
same length as <var title="">input list</var>, all zero.</p>
<p>Entries in <var title="">output list</var> correspond to the
entries in <var title="">input list</var> that have the same
position.</p>
</li>
<li><p>Let <var title="">input dimension</var> be the size passed
to the algorithm.</p>
<li>
<p>Let <var title="">count percentage</var> be the number of
entries in <var title="">input list</var> whose unit is
<i>percentage</i>.</p>
<p>Let <var title="">total percentage</var> be the sum of all the
numbers in <var title="">input list</var> whose unit is
<i>percentage</i>.</p>
<p>Let <var title="">count relative</var> be the number of
entries in <var title="">input list</var> whose unit is
<i>relative</i>.</p>
<p>Let <var title="">total relative</var> be the sum of all the
numbers in <var title="">input list</var> whose unit is
<i>relative</i>.</p>
<p>Let <var title="">count absolute</var> be the number of
entries in <var title="">input list</var> whose unit is
<i>absolute</i>.</p>
<p>Let <var title="">total absolute</var> be the sum of all the
numbers in <var title="">input list</var> whose unit is
<i>absolute</i>.</p>
<p>Let <var title="">remaining space</var> be the value of <var
title="">input dimension</var>.</p>
</li>
<li>
<p>If <var title="">total absolute</var> is greater than <var
title="">remaining space</var>, then for each entry in <var
title="">input list</var> whose unit is <i>absolute</i>, set the
corresponding value in <var title="">output list</var> to the
number of the entry in <var title="">input list</var> multiplied
by <var title="">remaining space</var> and divided by <var
title="">total absolute</var>. Then, set <var title="">remaining
space</var> to zero.</p>
<p>Otherwise, for each entry in <var title="">input list</var>
whose unit is <i>absolute</i>, set the corresponding value in <var
title="">output list</var> to the number of the entry in <var
title="">input list</var>. Then, decrement <var title="">remaining
space</var> by <var title="">total absolute</var>.</p>
</li>
<li>
<p>If <var title="">total percentage</var> multiplied by the <var
title="">input dimension</var> and divided by 100 is greater than
<var title="">remaining space</var>, then for each entry in <var
title="">input list</var> whose unit is <i>percentage</i>, set the
corresponding value in <var title="">output list</var> to the
number of the entry in <var title="">input list</var> multiplied
by <var title="">remaining space</var> and divided by <var
title="">total percentage</var>. Then, set <var title="">remaining
space</var> to zero.</p>
<p>Otherwise, for each entry in <var title="">input list</var>
whose unit is <i>percentage</i>, set the corresponding value in
<var title="">output list</var> to the number of the entry in <var
title="">input list</var> multiplied by the <var title="">input
dimension</var> and divided by 100. Then, decrement <var
title="">remaining space</var> by <var title="">total
percentage</var> multiplied by the <var title="">input
dimension</var> and divided by 100.</p>
</li>
<li>
<p>For each entry in <var title="">input list</var> whose unit is
<i>relative</i>, set the corresponding value in <var
title="">output list</var> to the number of the entry in <var
title="">input list</var> multiplied by <var title="">remaining
space</var> and divided by <var title="">total relative</var>.</p>
</li>
<li><p>Return <var title="">output list</var>.</p></li>
</ol>
<p>User agents working with integer values for frame widths (as
opposed to user agents that can lay frames out with subpixel
accuracy) are expected to distribute the remainder first the last
entry whose unit is <i>relative</i>, then equally (not
proportionally) to each entry whose unit is <i>percentage</i>, then
equally (not proportionally) to each entry whose unit is
<i>absolute</i>, and finally, failing all else, to the last
entry.</p>
</div>
<div class="impl">
<h3>Interactive media</h3>
<h4>Links, forms, and navigation</h4>
<p>User agents are expected to allow the user to control aspects of
<span>hyperlink</span> activation and <span>form submission</span>,
such as which <span>browsing context</span> is to be used for the
subsequent <span title="navigate">navigation</span>.</p>
<p>User agents are expected to allow users to discover the
destination of <span title="hyperlink">hyperlinks</span> and of
<span title="form">forms</span> before triggering their <span
title="navigate">navigation</span>.</p>
<p>User agents are expected to inform the user of whether a
<span>hyperlink</span> includes <span>hyperlink auditing</span>, and
to let them know at a minimum which domains will be contacted as
part of such auditing.</p>
<p>User agents are expected to allow users to <span>navigate</span>
<span title="browsing context">browsing contexts</span> to the
resources <span title="resolve a url">indicated</span> by the <code
title="">cite</code> attributes on <code>q</code>,
<code>blockquote</code>, <code>section</code>, <code>article</code>,
<code>ins</code>, and <code>del</code> elements.</p>
<p>User agents are expected to surface <span
title="hyperlink">hyperlinks</span> created by <code>link</code>
elements in their user interface.</p>
<p class="note">While <code>link</code> elements that create <span
title="hyperlink">hyperlinks</span> will match the ':link' or
':visited' pseudo-classes, will react to clicks if visible, and so
forth, this does not extend to any browser interface constructs that
expose those same links. Activating a link through the browser's
interface, rather than in the page itself, does not trigger <code
title="event-click">click</code> events and the like.</p>
<h4>The <code title="attr-title">title</code> attribute</h4>
<p>Given an element (e.g. the element designated by the mouse
cursor), if the element, or one of its ancestors, has a <code
title="attr-title">title</code> attribute, and the nearest such
attribute has a value that is not the empty string, it is expected
that the user agent will expose the contents of that attribute as a
tooltip.</p>
<p>User agents are encouraged to make it possible to view tooltips
without the use of a pointing device, since not all users are able
to use pointing devices.</p>
<p>U+000A LINE FEED (LF) characters are expected to cause line
breaks in the tooltip.</p>
<h4>Editing hosts</h4>
<p>The current text editing caret (the one at the <span>caret
position</span> in a focused <span>editing host</span>) is expected
to act like an inline replaced element with the vertical dimensions
of the caret and with zero width for the purposes of the CSS
rendering model.</p>
<p class="note">This means that even an empty block can have the
caret inside it, and that when the caret is in such an element, it
prevents margins from collapsing through the element.</p>
<h3>Print media</h3>
<p>User agents are expected to allow the user to request the
opportunity to <dfn>obtain a physical form</dfn> (or a
representation of a physical form) of a <code>Document</code>. For
example, selecting the option to print a page or convert it to PDF
format.</p>
<p>When the user actually <span title="obtain a physical
form">obtains a physical form</span> (or a representation of a
physical form) of a <code>Document</code>, the user agent is
expected to create a new view with the print media, render the
result, and the discard the view.</p>
<h3>Interaction with CSS</h3>
<!-- v2: Extensions to CSS
for drag and drop
for datagrid [v2DATAGRID]
-->
<h4>Selectors</h4>
<p>Attribute and element <em>names</em> of <span>HTML
elements</span> in <span>HTML documents</span> must be treated as
<span>ASCII case-insensitive</span>.</p>
<p>Classes from the <code title="attr-class">class</code> attribute
of <span>HTML elements</span> in documents that are in <span>quirks
mode</span> must be treated as <span>ASCII
case-insensitive</span>.</p>
<p>Attribute selectors on an <span title="HTML elements">HTML
element</span> in an <span title="HTML documents">HTML
document</span> must treat the <em>values</em> of attributes with
the following names as <span>ASCII case-insensitive</span>:</p>
<!-- based on Mozilla's list, which was itself based on HTML4 -->
<!-- WebKit's was identical at the time of writing except as noted below -->
<ul class="brief">
<li><code title="">accept</code>
<li><code title="">accept-charset</code>
<li><code title="">align</code>
<li><code title="">alink</code>
<li><code title="">axis</code>
<li><code title="">bgcolor</code>
<li><code title="">charset</code>
<li><code title="">checked</code>
<li><code title="">clear</code>
<li><code title="">codetype</code>
<li><code title="">color</code>
<li><code title="">compact</code>
<li><code title="">declare</code>
<li><code title="">defer</code>
<li><code title="">dir</code>
<li><code title="">direction</code> <!-- not in webkit -->
<li><code title="">disabled</code>
<li><code title="">enctype</code>
<li><code title="">face</code>
<li><code title="">frame</code>
<li><code title="">hreflang</code>
<li><code title="">http-equiv</code>
<li><code title="">lang</code>
<li><code title="">language</code>
<li><code title="">link</code>
<li><code title="">media</code>
<li><code title="">method</code>
<li><code title="">multiple</code>
<li><code title="">nohref</code>
<li><code title="">noresize</code>
<li><code title="">noshade</code>
<li><code title="">nowrap</code>
<li><code title="">readonly</code>
<li><code title="">rel</code>
<li><code title="">rev</code>
<li><code title="">rules</code>
<li><code title="">scope</code>
<li><code title="">scrolling</code>
<li><code title="">selected</code>
<li><code title="">shape</code>
<li><code title="">target</code>
<li><code title="">text</code>
<li><code title="">type</code>
<li><code title="">valign</code>
<li><code title="">valuetype</code>
<li><code title="">vlink</code>
</ul>
<p>All other <span>HTML elements</span> and all attribute names and
values on <span>HTML elements</span> must be treated as
<span>case-sensitive</span>.</p>
</div>
<h2 id="obsolete">Obsolete features</h2>
<h3>Obsolete but conforming features</h3>
<p>Features listed in this section will trigger warnings in
conformance checkers.</p>
<p>In <span>the HTML syntax</span>, authors should not specify <span
title="syntax-DOCTYPE">DOCTYPE</span>s that get parsed as <span
title="obsolete permitted DOCTYPE">obsolete permitted
DOCTYPEs</span>.</p><!-- this is poor form; we really should define
this in the syntax section somehow -->
<p>Authors should not specify an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-content-language">Content
Language</span> state on a <code>meta</code> element. The <code
title="attr-lang">lang</code> attribute should be used instead.</p>
<p>Authors should not specify a <code
title="attr-img-border">border</code> attribute on an
<code>img</code> element. If the attribute is present, its value
must be the string "<code title="">0</code>". CSS should be used
instead.</p>
<p>Authors should not specify a <code
title="attr-script-language">language</code> attribute on a
<code>script</code> element. If the attribute is present, its value
must be an <span>ASCII case-insensitive</span> match for the string
"<code title="">JavaScript</code>" and either the <code
title="attr-script-type">type</code> attribute must be omitted or
its value must be an <span>ASCII case-insensitive</span> match for
the string "<code title="">text/javascript</code>". The attribute
should be entirely omitted instead (with the value "<code
title="">JavaScript</code>", it has no effect), or replaced with use
of the <code title="attr-script-type">type</code> attribute.</p>
<p>Authors should not specify the <code
title="attr-a-name">name</code> attribute on <code>a</code>
elements. If the attribute is present, its value must not be the
empty string and must neither be equal to the value of any of the
<span title="concept-id">IDs</span> in the element's <span>home
subtree</span> other than the element's own <span
title="concept-id">ID</span>, if any, nor be equal to the value of
any of the other <code title="attr-a-name">name</code> attributes on
<code>a</code> elements in the element's <span>home
subtree</span>. If this attribute is present and the element has an
<span title="concept-id">ID</span>, then the attribute's value must
be equal to the element's <span title="concept-id">ID</span>. In
earlier versions of the language, this attribute was intended as a
way to specify possible targets for fragment identifiers in <span
title="URL">URLs</span>. The <code title="attr-id">id</code>
attribute should be used instead.</p>
<p class="note">The <code title="attr-table-summary">summary</code>
attribute, defined in the <code>table</code> section, will also
trigger a warning.</p>
<div class="impl">
<h4>Warnings for obsolete but conforming features</h4>
<p>To ease the transition from HTML4 Transitional documents to the
language defined in <em>this</em> specification, and to discourage
certain features that are only allowed in very few circumstances,
conformance checkers are required to warn the user when the
following features are used in a document. These are generally old
obsolete features that have no effect, and are allowed only to
distinguish between likely mistakes (regular conformance errors) and
mere vestigial markup or unusual and discouraged practices (these
warnings).</p>
<p>The following features must be categorized as described
above:</p>
<ul><!-- downplayed list -->
<li><p>The presence of an <span>obsolete permitted DOCTYPE</span>
in an <span title="HTML documents">HTML document</span>.</p></li>
<li><p>The presence of a <code>meta</code> element with an <code
title="attr-meta-http-equiv">http-equiv</code> attribute in the
<span title="attr-meta-http-equiv-content-language">Content
Language</span> state.</p></li>
<li><p>The presence of a <code
title="attr-img-border">border</code> attribute on an
<code>img</code> element if its value is the string "<code
title="">0</code>".</p></li>
<li><p>The presence of a <code
title="attr-script-language">language</code> attribute on a
<code>script</code> element if its value is an <span>ASCII
case-insensitive</span> match for the string "<code
title="">JavaScript</code>" and if there is no <code
title="attr-script-type">type</code> attribute or there is and its
value is an <span>ASCII case-insensitive</span> match for the
string "<code title="">text/javascript</code>".</p></li>
<li><p>The presence of a <code title="attr-a-name">name</code>
attribute on an <code>a</code> element, if its value is not the
empty string.</p></li>
<li><p>The presence of a <code
title="attr-table-summary">summary</code> attribute on a
<code>table</code> element.</p></li> <!-- 2.65% pages -->
</ul>
<p>Conformance checkers must distinguish between pages that have no
conformance errors and have none of these obsolete features, and
pages that have no conformance errors but do have some of these
obsolete features.</p>
<p class="example">For example, a validator could report some pages
as "Valid HTML5" and others as "Valid HTML5 with warnings".</p>
</div>
<h3>Non-conforming features</h3>
<p>Elements in the following list are entirely obsolete, and must
not be used by authors:</p>
<dl><!-- alphabetical by first element in the group, except CSS goes last -->
<dt><code>applet</code></dt>
<dd><p>Use <code>embed</code> or <code>object</code> instead.</p></dd>
<dt><dfn><code>acronym</code></dfn></dt>
<dd><p>Use <code>abbr</code> instead.</p></dd>
<dt><dfn><code>dir</code></dfn></dt>
<dd><p>Use <code>ul</code> instead.</p></dd>
<dt><code>frame</code></dt>
<dt><code>frameset</code></dt>
<dt><dfn><code>noframes</code></dfn></dt>
<dd><p>Either use <code>iframe</code> and CSS instead, or use server-side includes to generate complete pages with the various invariant parts merged in.</p></dd>
<dt><dfn><code>isindex</code></dfn></dt>
<dd><p>Use an explicit <code>form</code> and <span title="attr-input-type-text">text field</span> combination instead.</p></dd>
<dt><dfn><code>listing</code></dfn></dt>
<dt><dfn><code>xmp</code></dfn></dt>
<dd><p>Use <code>pre</code> and <code>code</code> instead.</p></dd>
<dt><dfn><code>nextid</code></dfn></dt>
<dd><p>Use GUIDs instead.</p></dd>
<dt><dfn><code>noembed</code></dfn></dt>
<dd><p>Use <code>object</code> instead of <code>embed</code> when fallback is necessary.</p></dd>
<dt><dfn><code>plaintext</code></dfn></dt>
<dd><p>Use the "<code>text/plain</code>" <span>MIME type</span> instead.</p></dd>
<dt><dfn><code>rb</code></dfn></dt>
<dd><p>Providing the ruby base directly inside the <code>ruby</code> element is sufficient; the <code>rb</code> element is unnecessary. Omit it altogether.</p></dd>
<dt><dfn><code>basefont</code></dfn></dt>
<dt><dfn><code>big</code></dfn></dt>
<dt><dfn><code>blink</code></dfn></dt>
<dt><dfn><code>center</code></dfn></dt>
<dt><dfn><code>font</code></dfn></dt>
<dt><code>marquee</code></dt>
<dt><dfn><code>s</code></dfn></dt>
<dt><dfn><code>spacer</code></dfn></dt>
<dt><dfn><code>strike</code></dfn></dt>
<dt><dfn><code>tt</code></dfn></dt>
<dt><dfn><code>u</code></dfn></dt>
<dd><p>Use CSS instead.</p></dd>
</dl>
<hr>
<p>The following attributes are obsolete (though the elements are
still part of the language), and must not be used by authors:</p>
<dl><!-- alphabetical by element then attribute of first item in group, except CSS goes last -->
<dt><dfn title="attr-a-charset"><code>charset</code></dfn> on <code>a</code> elements</dt>
<dt><dfn title="attr-link-charset"><code>charset</code></dfn> on <code>link</code> elements</dt>
<dd><p>Use an HTTP Content-Type header on the linked resource instead.</p></dd>
<dt><dfn title="attr-a-coords"><code>coords</code></dfn> on <code>a</code> elements</dt>
<dt><dfn title="attr-a-shape"><code>shape</code></dfn> on <code>a</code> elements</dt>
<dd><p>Use <code>area</code> instead of <code>a</code> for image maps.</p></dd>
<dt><dfn title="attr-a-methods"><code>methods</code></dfn> on <code>a</code> elements</dt>
<dd><p>Use the HTTP OPTIONS feature instead.</p></dd>
<dt><dfn title="attr-a-name"><code>name</code></dfn> on <code>a</code> elements (except as noted in the previous section)</dt>
<dt><dfn title="attr-embed-name"><code>name</code></dfn> on <code>embed</code> elements</dt>
<dt><dfn title="attr-img-name"><code>name</code></dfn> on <code>img</code> elements</dt>
<dd><p>Use the <code title="attr-id">id</code> attribute instead.</p></dd>
<dt><dfn title="attr-a-rev"><code>rev</code></dfn> on <code>a</code> elements</dt>
<dt><dfn title="attr-link-rev"><code>rev</code></dfn> on <code>link</code> elements</dt>
<dd><p>Use the <code title="attr-hyperlink-rel">rel</code>
attribute instead, with an opposite term. (For example, instead of
<code title="">rev="made"</code>, use <code
title="">rel="author"</code>.)</p></dd>
<dt><dfn title="attr-a-urn"><code>urn</code></dfn> on <code>a</code> elements</dt>
<dd><p>Specify the preferred persistent identifier using the <code title="attr-href">href</code> attribute instead.</p></dd>
<dt><dfn title="attr-area-nohref"><code>nohref</code></dfn> on <code>area</code> elements</dt>
<dd><p>Omitting the <code title="attr-hyperlink-href">href</code>
attribute is sufficient; the <code
title="attr-area-nohref">nohref</code> attribute is
unnecessary. Omit it altogether.</p></dd>
<dt><dfn title="attr-head-profile"><code>profile</code></dfn> on <code>head</code> elements</dt>
<dd><p>When used for declaring which <code>meta</code> terms are
used in the document, unnecessary; omit it altogether, and <span
title="concept-meta-extensions">register the names</span>.</p></dd>
<dd><p>When used for triggering specific user agent behaviors: use
a <code>link</code> element instead.</p></dd>
<dt><dfn title="attr-html-version"><code>version</code></dfn> on <code>html</code> elements</dt>
<dd><p>Unnecessary. Omit it altogether.</p></dd>
<dt><dfn title="attr-input-usemap"><code>usemap</code></dfn> on <code>input</code> elements</dt>
<dd><p>Use <code>img</code> instead of <code>input</code> for image maps.</p></dd>
<dt><dfn title="attr-iframe-longdesc"><code>longdesc</code></dfn> on <code>iframe</code> elements</dt>
<dt><dfn title="attr-img-longdesc"><code>longdesc</code></dfn> on <code>img</code> elements</dt>
<dd><p>Use a regular <code>a</code> element to link to the description.</p></dd>
<dt><dfn title="attr-link-target"><code>target</code></dfn> on <code>link</code> elements</dt>
<dd><p>Unnecessary. Omit it altogether.</p></dd>
<dt><dfn title="attr-meta-scheme"><code>scheme</code></dfn> on <code>meta</code> elements</dt>
<dd><p>Use only one scheme per field, or make the scheme declaration part of the value.</p></dd>
<dt><dfn title="attr-object-archive"><code>archive</code></dfn> on <code>object</code> elements</dt>
<dt><dfn title="attr-object-classid"><code>classid</code></dfn> on <code>object</code> elements</dt>
<dt><dfn title="attr-object-code"><code>code</code></dfn> on <code>object</code> elements</dt>
<dt><dfn title="attr-object-codebase"><code>codebase</code></dfn> on <code>object</code> elements</dt>
<dt><dfn title="attr-object-codetype"><code>codetype</code></dfn> on <code>object</code> elements</dt>
<dd><p>Use the <code title="attr-object-data">data</code> and <code
title="attr-object-type">type</code> attributes to invoke <span
title="plugin">plugins</span>. To set parameters with these names
in particular, the <code>param</code> element can be used.</p></dd>
<dt><dfn title="attr-object-declare"><code>declare</code></dfn> on <code>object</code> elements</dt>
<dd><p>Repeat the <code>object</code> element completely each time the resource is to be reused.</p></dd>
<dt><dfn title="attr-object-standby"><code>standby</code></dfn> on <code>object</code> elements</dt>
<dd><p>Optimise the linked resource so that it loads quickly or, at least, incrementally.</p></dd>
<dt><dfn title="attr-param-type"><code>type</code></dfn> on <code>param</code> elements</dt>
<dt><dfn title="attr-param-valuetype"><code>valuetype</code></dfn> on <code>param</code> elements</dt>
<dd><p>Use the <code title="attr-param-name">name</code> and <code
title="attr-param-value">value</code> attributes without declaring
value types.</p></dd>
<dt><dfn title="attr-script-language"><code>language</code></dfn> on <code>script</code> elements (except as noted in the previous section)</dt>
<dd><p>Use the <code title="attr-script-type">type</code> attribute
instead.</p></dd>
<dt><dfn title="attr-tdth-abbr"><code>abbr</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dd><p>Use text that begins in an unambiguous and terse manner, and include any more elaborate text after that.</p>
<dt><dfn title="attr-tdth-axis"><code>axis</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dd><p>Use the <code title="attr-th-scope">scope</code> attribute.</p>
<dt><dfn title="attr-body-alink"><code>alink</code></dfn> on <code>body</code> elements</dt>
<dt><dfn title="attr-body-background"><code>background</code></dfn> on <code>body</code> elements</dt>
<dt><dfn title="attr-body-bgcolor"><code>bgcolor</code></dfn> on <code>body</code> elements</dt>
<dt><dfn title="attr-body-link"><code>link</code></dfn> on <code>body</code> elements</dt>
<dt><dfn title="attr-body-text"><code>text</code></dfn> on <code>body</code> elements</dt>
<dt><dfn title="attr-body-vlink"><code>vlink</code></dfn> on <code>body</code> elements</dt>
<dt><dfn title="attr-br-clear"><code>clear</code></dfn> on <code>br</code> elements</dt>
<dt><dfn title="attr-caption-align"><code>align</code></dfn> on <code>caption</code> elements</dt>
<dt><dfn title="attr-col-align"><code>align</code></dfn> on <code>col</code> elements</dt>
<dt><dfn title="attr-col-char"><code>char</code></dfn> on <code>col</code> elements</dt>
<dt><dfn title="attr-col-charoff"><code>charoff</code></dfn> on <code>col</code> elements</dt>
<dt><dfn title="attr-col-valign"><code>valign</code></dfn> on <code>col</code> elements</dt>
<dt><dfn title="attr-col-width"><code>width</code></dfn> on <code>col</code> elements</dt>
<dt><dfn title="attr-div-align"><code>align</code></dfn> on <code>div</code> elements</dt>
<dt><dfn title="attr-dl-compact"><code>compact</code></dfn> on <code>dl</code> elements</dt>
<dt><dfn title="attr-embed-align"><code>align</code></dfn> on <code>embed</code> elements</dt>
<dt><dfn title="attr-hr-align"><code>align</code></dfn> on <code>hr</code> elements</dt>
<dt><dfn title="attr-hr-noshade"><code>noshade</code></dfn> on <code>hr</code> elements</dt>
<dt><dfn title="attr-hr-size"><code>size</code></dfn> on <code>hr</code> elements</dt>
<dt><dfn title="attr-hr-width"><code>width</code></dfn> on <code>hr</code> elements</dt>
<dt><dfn title="attr-hx-align"><code>align</code></dfn> on <code>h1</code>—<code>h6</code> elements</dt>
<dt><dfn title="attr-iframe-align"><code>align</code></dfn> on <code>iframe</code> elements</dt>
<dt><dfn title="attr-iframe-frameborder"><code>frameborder</code></dfn> on <code>iframe</code> elements</dt>
<dt><dfn title="attr-iframe-marginheight"><code>marginheight</code></dfn> on <code>iframe</code> elements</dt>
<dt><dfn title="attr-iframe-marginwidth"><code>marginwidth</code></dfn> on <code>iframe</code> elements</dt>
<dt><dfn title="attr-iframe-scrolling"><code>scrolling</code></dfn> on <code>iframe</code> elements</dt>
<dt><dfn title="attr-input-align"><code>align</code></dfn> on <code>input</code> elements</dt>
<dt><dfn title="attr-img-align"><code>align</code></dfn> on <code>img</code> elements</dt>
<dt><dfn title="attr-img-border"><code>border</code></dfn> on <code>img</code> elements (except as noted in the previous section)</dt>
<dt><dfn title="attr-img-hspace"><code>hspace</code></dfn> on <code>img</code> elements</dt>
<dt><dfn title="attr-img-vspace"><code>vspace</code></dfn> on <code>img</code> elements</dt>
<dt><dfn title="attr-legend-align"><code>align</code></dfn> on <code>legend</code> elements</dt>
<dt><dfn title="attr-li-type"><code>type</code></dfn> on <code>li</code> elements</dt>
<dt><dfn title="attr-menu-compact"><code>compact</code></dfn> on <code>menu</code> elements</dt>
<dt><dfn title="attr-object-align"><code>align</code></dfn> on <code>object</code> elements</dt>
<dt><dfn title="attr-object-border"><code>border</code></dfn> on <code>object</code> elements</dt>
<dt><dfn title="attr-object-hspace"><code>hspace</code></dfn> on <code>object</code> elements</dt>
<dt><dfn title="attr-object-vspace"><code>vspace</code></dfn> on <code>object</code> elements</dt>
<dt><dfn title="attr-ol-compact"><code>compact</code></dfn> on <code>ol</code> elements</dt>
<dt><dfn title="attr-ol-type"><code>type</code></dfn> on <code>ol</code> elements</dt>
<dt><dfn title="attr-p-align"><code>align</code></dfn> on <code>p</code> elements</dt>
<dt><dfn title="attr-pre-width"><code>width</code></dfn> on <code>pre</code> elements</dt>
<dt><dfn title="attr-table-align"><code>align</code></dfn> on <code>table</code> elements</dt>
<dt><dfn title="attr-table-bgcolor"><code>bgcolor</code></dfn> on <code>table</code> elements</dt>
<dt><dfn title="attr-table-border"><code>border</code></dfn> on <code>table</code> elements</dt>
<dt><dfn title="attr-table-cellpadding"><code>cellpadding</code></dfn> on <code>table</code> elements</dt>
<dt><dfn title="attr-table-cellspacing"><code>cellspacing</code></dfn> on <code>table</code> elements</dt>
<dt><dfn title="attr-table-frame"><code>frame</code></dfn> on <code>table</code> elements</dt>
<dt><dfn title="attr-table-rules"><code>rules</code></dfn> on <code>table</code> elements</dt>
<dt><dfn title="attr-table-width"><code>width</code></dfn> on <code>table</code> elements</dt>
<dt><dfn title="attr-tbody-align"><code>align</code></dfn> on <code>tbody</code>, <code>thead</code>, and <code>tfoot</code> elements</dt>
<dt><dfn title="attr-tbody-char"><code>char</code></dfn> on <code>tbody</code>, <code>thead</code>, and <code>tfoot</code> elements</dt>
<dt><dfn title="attr-tbody-charoff"><code>charoff</code></dfn> on <code>tbody</code>, <code>thead</code>, and <code>tfoot</code> elements</dt>
<dt><dfn title="attr-tbody-vAlign"><code>valign</code></dfn> on <code>tbody</code>, <code>thead</code>, and <code>tfoot</code> elements</dt>
<dt><dfn title="attr-tdth-align"><code>align</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dt><dfn title="attr-tdth-bgcolor"><code>bgcolor</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dt><dfn title="attr-tdth-char"><code>char</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dt><dfn title="attr-tdth-charoff"><code>charoff</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dt><dfn title="attr-tdth-height"><code>height</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dt><dfn title="attr-tdth-nowrap"><code>nowrap</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dt><dfn title="attr-tdth-valign"><code>valign</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dt><dfn title="attr-tdth-width"><code>width</code></dfn> on <code>td</code> and <code>th</code> elements</dt>
<dt><dfn title="attr-tr-align"><code>align</code></dfn> on <code>tr</code> elements</dt>
<dt><dfn title="attr-tr-bgcolor"><code>bgcolor</code></dfn> on <code>tr</code> elements</dt>
<dt><dfn title="attr-tr-char"><code>char</code></dfn> on <code>tr</code> elements</dt>
<dt><dfn title="attr-tr-charoff"><code>charoff</code></dfn> on <code>tr</code> elements</dt>
<dt><dfn title="attr-tr-valign"><code>valign</code></dfn> on <code>tr</code> elements</dt>
<dt><dfn title="attr-ul-compact"><code>compact</code></dfn> on <code>ul</code> elements</dt>
<dt><dfn title="attr-ul-type"><code>type</code></dfn> on <code>ul</code> elements</dt>
<dd><p>Use CSS instead.</p></dd>
</dl>
<div class="impl">
<h3>Requirements for implementations</h3>
<h4>The <dfn><code>applet</code></dfn> element</h4>
<p>The <code>applet</code> element is a Java-specific variant of the
<code>embed</code> element. The <code>applet</code> element is now
obsoleted so that all extension frameworks (Java, .NET, Flash, etc)
are handled in a consistent manner.</p>
<p id="sandboxPluginApplet">When the element is not <span>in a
<code>Document</code></span>, and when the element's document is not
<span>fully active</span>, and when the <span>sandboxed plugins
browsing context flag</span> is set on the <span>browsing
context</span> for which the <code>applet</code> element's document
is the <span>active document</span>, and when the element has an
ancestor <span>media element</span>, and when the element has an
ancestor <code>object</code> element that is <em>not</em> showing
its <span>fallback content</span>, and when no Java Language runtime
<span>plugin</span> is available, and when one <em>is</em> available
but it is disabled, the element <span>represents</span> its
contents.</p>
<p>Otherwise, the user agent should instantiate a Java Language
runtime <span>plugin</span>, and should pass the names and values of
all the attributes on the element, and <!-- then a parameter named
"PARAM" whose value is null, and then --> all the names and values
of <span title="concept-param-parameter">parameters</span> given by
<code>param</code> elements that are children of the
<code>applet</code> element, in <span>tree order</span>, to the
<span>plugin</span> used. If the <span>plugin</span> supports a
scriptable interface, the <code>HTMLAppletElement</code> object
representing the element should expose that interface. The
<code>applet</code> element <span>represents</span> the
<span>plugin</span>.</p>
<!-- If we ever make this fetch anything manually, remember to delay
the load event, and to include ", from the element's <span>browsing
context scope origin</span> if it has one" when fetching -->
<p class="note">The <code>applet</code> element is unaffected by the
CSS 'display' property. The Java Language runtime is instantiated
even if the element is hidden with a 'display:none' CSS style.</p>
<p>The <code>applet</code> element must implement the
<code>HTMLAppletElement</code> interface.</p>
<pre class="idl">interface <dfn>HTMLAppletElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-applet-align">align</span>;
attribute DOMString <span title="dom-applet-alt">alt</span>;
attribute DOMString <span title="dom-applet-archive">archive</span>;
attribute DOMString <span title="dom-applet-code">code</span>;
attribute DOMString <span title="dom-applet-codeBase">codeBase</span>;
attribute DOMString <span title="dom-applet-height">height</span>;
attribute unsigned long <span title="dom-applet-hspace">hspace</span>;
attribute DOMString <span title="dom-applet-name">name</span>;
attribute DOMString _<span title="dom-applet-object">object</span>; // the underscore is not part of the identifier <!-- it's a Web IDL escaping mechanism -->
attribute unsigned long <span title="dom-applet-vspace">vspace</span>;
attribute DOMString <span title="dom-applet-width">width</span>;
};</pre>
<p>The <dfn title="dom-applet-align"><code>align</code></dfn>, <dfn
title="dom-applet-alt"><code>alt</code></dfn>, <dfn
title="dom-applet-archive"><code>archive</code></dfn>, <dfn
title="dom-applet-code"><code>code</code></dfn>, <dfn
title="dom-applet-height"><code>height</code></dfn>, <dfn
title="dom-applet-hspace"><code>hspace</code></dfn>, <dfn
title="dom-applet-name"><code>name</code></dfn>, <dfn
title="dom-applet-object"><code>object</code></dfn>, <dfn
title="dom-applet-vspace"><code>vspace</code></dfn>, and <dfn
title="dom-applet-width"><code>width</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name.</p>
<p>The <dfn title="dom-applet-codeBase"><code>codeBase</code></dfn>
IDL attribute must <span>reflect</span> the <code
title="attr-applet-codebase">codebase</code> content attribute.</p>
<h4>The <dfn><code>marquee</code></dfn> element</h4>
<p>The <code>marquee</code> element is a presentational element that
animates content. CSS transitions and animations are a more
appropriate mechanism.</p>
<p>The <span>task source</span> for tasks mentioned in this section
is the <span>DOM manipulation task source</span>.</p>
<p>The <code>marquee</code> element must implement the
<code>HTMLMarqueeElement</code> interface.</p>
<pre class="idl">interface <dfn>HTMLMarqueeElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-marquee-behavior">behavior</span>;
attribute DOMString <span title="dom-marquee-bgColor">bgColor</span>;
attribute DOMString <span title="dom-marquee-direction">direction</span>;
attribute DOMString <span title="dom-marquee-height">height</span>;
attribute unsigned long <span title="dom-marquee-hspace">hspace</span>;
attribute long <span title="dom-marquee-loop">loop</span>;
attribute unsigned long <span title="dom-marquee-scrollamount">scrollAmount</span>;
attribute unsigned long <span title="dom-marquee-scrollDelay">scrollDelay</span>;
attribute DOMString <span title="dom-marquee-trueSpeed">trueSpeed</span>;
attribute unsigned long <span title="dom-marquee-vspace">vspace</span>;
attribute DOMString <span title="dom-marquee-width">width</span>;
attribute <span>Function</span> <span title="handler-marquee-onbounce">onbounce</span>;
attribute <span>Function</span> <span title="handler-marquee-onfinish">onfinish</span>;
attribute <span>Function</span> <span title="handler-marquee-onstart">onstart</span>;
void <span title="dom-marquee-start">start</span>();
void <span title="dom-marquee-stop">stop</span>();
};</pre>
<p>A <code>marquee</code> element can be <dfn
title="concept-marquee-on">turned on</dfn> or <dfn
title="concept-marquee-off">turned off</dfn>. When it is created, it
is <span title="concept-marquee-on">turned on</span>.</p>
<p>When the <dfn
title="dom-marquee-start"><code>start()</code></dfn> method is
called, the <code>marquee</code> element must be <span
title="concept-marquee-on">turned on</span>.</p>
<p>When the <dfn title="dom-marquee-stop"><code>stop()</code></dfn>
method is called, the <code>marquee</code> element must be <span
title="concept-marquee-off">turned off</span>.</p>
<p>When a <code>marquee</code> element is created, the user agent
must <span>queue a task</span> to <span>fire a simple event</span>
named <code title="event-start">start</code> at the element.</p>
<hr>
<p>The <dfn
title="attr-marquee-behavior"><code>behavior</code></dfn> content
attribute on <code>marquee</code> elements is an <span>enumerated
attribute</span> with the following keywords (all
non-conforming):</p>
<table>
<thead>
<tr>
<th>Keyword
<th>State
<tbody>
<tr>
<td><code title="">scroll</code>
<td><dfn title="attr-marquee-behavior-scroll">scroll</dfn>
<tr>
<td><code title="">slide</code>
<td><dfn title="attr-marquee-behavior-slide">slide</dfn>
<tr>
<td><code title="">alternate</code>
<td><dfn title="attr-marquee-behavior-alternate">alternate</dfn>
</table>
<p>The <i>missing value default</i> is the <span
title="attr-marquee-behavior-scroll">scroll</span> state.</p>
<hr>
<p>The <dfn
title="attr-marquee-direction"><code>direction</code></dfn> content
attribute on <code>marquee</code> elements is an <span>enumerated
attribute</span> with the following keywords (all
non-conforming):</p>
<table>
<thead>
<tr>
<th>Keyword
<th>State
<tbody>
<tr>
<td><code title="">left</code>
<td><dfn title="attr-marquee-direction-left">left</dfn>
<tr>
<td><code title="">right</code>
<td><dfn title="attr-marquee-direction-right">right</dfn>
<tr>
<td><code title="">up</code>
<td><dfn title="attr-marquee-direction-up">up</dfn>
<tr>
<td><code title="">down</code>
<td><dfn title="attr-marquee-direction-down">down</dfn>
</table>
<p>The <i>missing value default</i> is the <span
title="attr-marquee-direction-left">left</span> state.</p>
<hr>
<p>The <dfn
title="attr-marquee-truespeed"><code>truespeed</code></dfn> content
attribute on <code>marquee</code> elements is an <span>enumerated
attribute</span> with the following keywords (all
non-conforming):</p>
<table>
<thead>
<tr>
<th>Keyword
<th>State
<tbody>
<tr>
<td><code title="">true</code>
<td><dfn title="attr-marquee-truespeed-true">true</dfn>
<tr>
<td><code title="">false</code>
<td><dfn title="attr-marquee-truespeed-false">false</dfn>
</table>
<p>The <i>missing value default</i> is the <span
title="attr-marquee-truespeed-false">false</span> state.</p>
<hr>
<p>A <code>marquee</code> element has a <dfn>marquee scroll
interval</dfn>, which is obtained as follows:</p>
<ol>
<li><p>If the element has a <code
title="attr-marquee-scrolldelay">scrolldelay</code> attribute, and
parsing its value using the <span>rules for parsing non-negative
integers</span> does not return an error, then let <var
title="">delay</var> be the parsed value. Otherwise, let <var
title="">delay</var> be 85.</p></li>
<li><p>If the element does not have a <code
title="attr-marquee-truespeed">truespeed</code> attribute, or if it
does but that attribute is in the <span
title="attr-marquee-truespeed-false">false</span> state, and the
<var title="">delay</var> value is less than 60, then let <var
title="">delay</var> be 60 instead.</p></li>
<li><p>The <span>marquee scroll interval</span> is <var
title="">delay</var>, interpreted in milliseconds.</p></li>
</ol>
<hr>
<p>A <code>marquee</code> element has a <dfn>marquee scroll
distance</dfn>, which, if the element has a <code
title="attr-marquee-scrollamount">scrollamount</code> attribute, and
parsing its value using the <span>rules for parsing non-negative
integers</span> does not return an error, is the parsed value
interpreted in CSS pixels, and otherwise is 6 CSS pixels.</p>
<hr>
<p>A <code>marquee</code> element has a <dfn>marquee loop
count</dfn>, which, if the element has a <code
title="attr-marquee-loop">loop</code> attribute, and parsing its
value using the <span>rules for parsing integers</span> does not
return an error or a number less than 1, is the parsed value, and
otherwise is −1.</p>
<p>The <dfn title="dom-marquee-loop"><code>loop</code></dfn> IDL
attribute, on getting, must return the element's <span>marquee loop
count</span>; and on setting, if the new value is different than the
element's <span>marquee loop count</span> and either greater than
zero or equal to −1, must set the element's <code
title="attr-marquee-loop">loop</code> content attribute (adding it
if necessary) to the <span>valid integer</span> that represents the
new value. (Other values are ignored.)</p>
<p>A <code>marquee</code> element also has a <dfn>marquee current
loop index</dfn>, which is zero when the element is created.</p>
<p>The rendering layer will occasionally <dfn>increment the marquee
current loop index</dfn>, which must cause the following steps to be
run:</p>
<ol>
<li><p>If the <span>marquee loop count</span> is −1, then
abort these steps.</p>
<li><p>Increment the <span>marquee current loop index</span> by
one.</p></li>
<li>
<p>If the <span>marquee current loop index</span> is now equal to
or greater than the element's <span>marquee loop count</span>,
<span title="concept-marquee-off">turn off</span> the
<code>marquee</code> element and <span>queue a task</span> to
<span>fire a simple event</span> named <code
title="event-finish">finish</code> at the <code>marquee</code>
element.</p>
<p>Otherwise, if the <code
title="attr-marquee-behavior">behavior</code> attribute is in the
<span title="attr-marquee-behavior-alternate">alternate</span>
state, then <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-bounce">bounce</code> at
the <code>marquee</code> element.</p>
<p>Otherwise, <span>queue a task</span> to <span>fire a simple
event</span> named <code title="event-start">start</code> at the
<code>marquee</code> element.</p>
</li>
</ol>
<hr>
<p>The following are the <span>event handlers</span> (and their
corresponding <span title="event handler event type">event handler
event types</span>) that must be supported, as content and IDL
attributes, by <code>marquee</code> elements:</p>
<table>
<thead>
<tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
<tbody>
<tr><td><dfn title="handler-marquee-onbounce"><code>onbounce</code></dfn> <td> <code title="event-bounce">bounce</code>
<tr><td><dfn title="handler-marquee-onfinish"><code>onfinish</code></dfn> <td> <code title="event-finish">finish</code>
<tr><td><dfn title="handler-marquee-onstart"><code>onstart</code></dfn> <td> <code title="event-start">start</code>
</table>
<hr>
<p>The <dfn
title="dom-marquee-behavior"><code>behavior</code></dfn>, <dfn
title="dom-marquee-direction"><code>direction</code></dfn>, <dfn
title="dom-marquee-height"><code>height</code></dfn>, <dfn
title="dom-marquee-hspace"><code>hspace</code></dfn>, <dfn
title="dom-marquee-vspace"><code>vspace</code></dfn>, and <dfn
title="dom-marquee-width"><code>width</code></dfn> IDL attributes
must <span>reflect</span> the respective content attributes of the
same name.</p>
<p>The <dfn title="dom-marquee-bgColor"><code>bgColor</code></dfn>
IDL attribute must <span>reflect</span> the <code
title="attr-marquee-bgcolor">bgcolor</code> content attribute.</p>
<p>The <dfn
title="dom-marquee-scrollAmount"><code>scrollAmount</code></dfn>
IDL attribute must <span>reflect</span> the <code
title="attr-marquee-scrollamount">scrollamount</code> content
attribute. The default value is 6.</p>
<p>The <dfn
title="dom-marquee-scrollDelay"><code>scrollDelay</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-marquee-scrolldelay">scrolldelay</code> content
attribute. The default value is 85.</p>
<p>The <dfn
title="dom-marquee-trueSpeed"><code>trueSpeed</code></dfn> IDL
attribute must <span>reflect</span> the <code
title="attr-marquee-truespeed">truespeed</code> content
attribute.</p>
<h4>Frames</h4>
<p>The <dfn><code>frameset</code></dfn> element acts as <span>the
body element</span> in documents that use frames.</p>
<p>The <code>frameset</code> element must implement the
<code>HTMLFrameSetElement</code> interface.</p>
<pre class="idl">interface <dfn>HTMLFrameSetElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-frameset-cols">cols</span>;
attribute DOMString <span title="dom-frameset-rows">rows</span>;
attribute <span>Function</span> <span title="handler-window-onafterprint">onafterprint</span>;
attribute <span>Function</span> <span title="handler-window-onbeforeprint">onbeforeprint</span>;
attribute <span>Function</span> <span title="handler-window-onbeforeunload">onbeforeunload</span>;
attribute <span>Function</span> <span title="handler-window-onblur">onblur</span>;
attribute <span>Function</span> <span title="handler-window-onerror">onerror</span>;
attribute <span>Function</span> <span title="handler-window-onfocus">onfocus</span>;
attribute <span>Function</span> <span title="handler-window-onhashchange">onhashchange</span>;
attribute <span>Function</span> <span title="handler-window-onload">onload</span>;
attribute <span>Function</span> <span title="handler-window-onmessage">onmessage</span>;
attribute <span>Function</span> <span title="handler-window-onoffline">onoffline</span>;
attribute <span>Function</span> <span title="handler-window-ononline">ononline</span>;
attribute <span>Function</span> <span title="handler-window-onpagehide">onpagehide</span>;
attribute <span>Function</span> <span title="handler-window-onpageshow">onpageshow</span>;
attribute <span>Function</span> <span title="handler-window-onpopstate">onpopstate</span>;
attribute <span>Function</span> <span title="handler-window-onredo">onredo</span>;
attribute <span>Function</span> <span title="handler-window-onresize">onresize</span>;
attribute <span>Function</span> <span title="handler-window-onstorage">onstorage</span>;
attribute <span>Function</span> <span title="handler-window-onundo">onundo</span>;
attribute <span>Function</span> <span title="handler-window-onunload">onunload</span>;
};</pre>
<p>The <dfn title="dom-frameset-cols"><code>cols</code></dfn> and
<dfn title="dom-frameset-rows"><code>rows</code></dfn> IDL
attributes of the <code>frameset</code> element must
<span>reflect</span> the respective content attributes of the same
name.</p>
<p>The <code>frameset</code> element must support the following
<span>event handler content attributes</span> exposing the
<span>event handlers</span> of the <code>Window</code> object:</p>
<ul class="brief">
<li><code title="handler-window-onafterprint">onafterprint</code></li>
<li><code title="handler-window-onbeforeprint">onbeforeprint</code></li>
<li><code title="handler-window-onbeforeunload">onbeforeunload</code></li>
<li><code title="handler-window-onblur">onblur</code></li>
<li><code title="handler-window-onerror">onerror</code></li>
<li><code title="handler-window-onfocus">onfocus</code></li>
<li><code title="handler-window-onhashchange">onhashchange</code></li>
<li><code title="handler-window-onload">onload</code></li>
<li><code title="handler-window-onmessage">onmessage</code></li>
<li><code title="handler-window-onoffline">onoffline</code></li>
<li><code title="handler-window-ononline">ononline</code></li>
<li><code title="handler-window-onpagehide">onpagehide</code></li>
<li><code title="handler-window-onpagehide">onpagehide</code></li>
<li><code title="handler-window-onpopstate">onpopstate</code></li>
<li><code title="handler-window-onredo">onredo</code></li>
<li><code title="handler-window-onresize">onresize</code></li>
<li><code title="handler-window-onstorage">onstorage</code></li>
<li><code title="handler-window-onundo">onundo</code></li>
<li><code title="handler-window-onunload">onunload</code></li>
</ul>
<p>The DOM interface also exposes <span>event handler IDL
attributes</span> that mirror those on the <code>Window</code>
element.</p>
<p>The <code title="handler-window-onblur">onblur</code>, <code
title="handler-window-onerror">onerror</code>, <code
title="handler-window-onfocus">onfocus</code>, and <code
title="handler-window-onload">onload</code> <span>event handler IDL
attributes</span> of the <code>Window</code> object, exposed on the
<code>frameset</code> element, shadow the generic <span>event
handler IDL attributes</span> with the same names normally supported
by <span>HTML elements</span>.</p>
<hr>
<p>The <dfn><code>frame</code></dfn> element defines a <span>nested
browsing context</span> similar to the <code>iframe</code> element,
but rendered within a <code>frameset</code> element.</p>
<p>When the browsing context is created, if a <code
title="attr-frame-src">src</code> attribute is present, the user
agent must <span title="resolve a url">resolve</span> the value of
that attribute, relative to the element, and if that is successful,
must then <span>navigate</span> the element's browsing context to
the resulting <span>absolute URL</span>, with <span>replacement
enabled</span>, and with the <code>frame</code> element's
document's <span>browsing context</span> as the <span>source
browsing context</span>.</p>
<p>Whenever the <code title="attr-frame-src">src</code> attribute
is set, the user agent must <span title="resolve a
url">resolve</span> the value of that attribute, relative to the
element, and if that is successful, the nested <span>browsing
context</span> must be <span title="navigate">navigated</span> to
the resulting <span>absolute URL</span>, with the
<code>frame</code> element's document's <span>browsing
context</span> as the <span>source browsing context</span>.</p>
<p>When the browsing context is created, if a <code
title="attr-frame-name">name</code> attribute is present, the
<span>browsing context name</span> must be set to the value of this
attribute; otherwise, the <span>browsing context name</span> must be
set to the empty string.</p>
<p>Whenever the <code title="attr-frame-name">name</code> attribute
is set, the nested <span>browsing context</span>'s <span
title="browsing context name">name</span> must be changed to the new
value. If the attribute is removed, the <span>browsing context
name</span> must be set to the empty string.</p>
<p>When content loads in a <code>frame</code>, after any <code
title="event-load">load</code> events are fired within the content
itself, the user agent must <span>queue a task</span> to <span>fire
a simple event</span> named <code title="event-load">load</code> at
the <code>frame</code> element. When content fails to load (e.g. due
to a network error), then the user agent must <span>queue a
task</span> to <span>fire a simple event</span> named <code
title="event-error">error</code> at the element instead.</p>
<p>The <span>task source</span> for the <span
title="concept-task">tasks</span> above is the <span>DOM
manipulation task source</span>.</p>
<p>When there is an <span>active parser</span> in the
<code>frame</code>, and when anything in the <code>frame</code> is
<span title="delay the load event">delaying the load event</span> of
the <code>frame</code>'s <span>browsing context</span>'s
<span>active document</span>, the <code>frame</code> must
<span>delay the load event</span> of its document.</p>
<p>The <code>frame</code> element must implement the
<code>HTMLFrameElement</code> interface.</p>
<pre class="idl">interface <dfn>HTMLFrameElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-frame-frameBorder">frameBorder</span>;
attribute DOMString <span title="dom-frame-longDesc">longDesc</span>;
attribute DOMString <span title="dom-frame-marginHeight">marginHeight</span>;
attribute DOMString <span title="dom-frame-marginWidth">marginWidth</span>;
attribute DOMString <span title="dom-frame-name">name</span>;
attribute boolean <span title="dom-frame-noResize">noResize</span>;
attribute DOMString <span title="dom-frame-scrolling">scrolling</span>;
attribute DOMString <span title="dom-frame-src">src</span>;
readonly attribute Document <span title="dom-frame-contentDocument">contentDocument</span>;
};</pre>
<p>The <dfn title="dom-frame-name"><code>name</code></dfn>, <dfn
title="dom-frame-scrolling"><code>scrolling</code></dfn>, and <dfn
title="dom-frame-src"><code>src</code></dfn> IDL attributes of the
<code>frame</code> element must <span>reflect</span> the respective
content attributes of the same name.</p>
<p>The <dfn
title="dom-frame-frameBorder"><code>frameBorder</code></dfn> IDL
attribute of the <code>frame</code> element must
<span>reflect</span> the element's <code
title="attr-frame-frameborder">frameborder</code> content
attribute.</p>
<p>The <dfn title="dom-frame-longDesc"><code>longDesc</code></dfn>
IDL attribute of the <code>frame</code> element must
<span>reflect</span> the element's <code
title="attr-frame-longdesc">longdesc</code> content attribute.</p>
<p>The <dfn
title="dom-frame-marginHeight"><code>marginHeight</code></dfn> IDL
attribute of the <code>frame</code> element must
<span>reflect</span> the element's <code
title="attr-frame-marginheight">marginheight</code> content
attribute.</p>
<p>The <dfn
title="dom-frame-marginWidth"><code>marginWidth</code></dfn> IDL
attribute of the <code>frame</code> element must
<span>reflect</span> the element's <code
title="attr-frame-marginwidth">marginwidth</code> content
attribute.</p>
<p>The <dfn title="dom-frame-noResize"><code>noResize</code></dfn>
IDL attribute of the <code>frame</code> element must
<span>reflect</span> the element's <code
title="attr-frame-noresize">noresize</code> content attribute.</p>
<p>The <dfn
title="dom-frame-contentDocument"><code>contentDocument</code></dfn>
IDL attribute of the <code>frame</code> element must return the
<code>Document</code> object of the <span>active document</span> of
the <code>frame</code> element's <span>nested browsing
context</span>.</p>
<h4>Other elements, attributes and APIs</h4> <!-- alphabetical by name and attribute -->
<p>User agents must treat <code>acronym</code> elements in a manner
equivalent to <code>abbr</code> elements.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLAnchorElement</span> {
attribute DOMString <span title="dom-a-coords">coords</span>;
attribute DOMString <span title="dom-a-charset">charset</span>;
attribute DOMString <span title="dom-a-name">name</span>;
attribute DOMString <span title="dom-a-rev">rev</span>;
attribute DOMString <span title="dom-a-shape">shape</span>;
};</pre>
<p>The <dfn title="dom-a-coords"><code>coords</code></dfn>, <dfn
title="dom-a-charset"><code>charset</code></dfn>, <dfn
title="dom-a-name"><code>name</code></dfn>, <dfn
title="dom-a-rev"><code>rev</code></dfn>, and <dfn
title="dom-a-shape"><code>shape</code></dfn> IDL attributes of the
<code>a</code> element must <span>reflect</span> the respective
content attributes of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLAreaElement</span> {
attribute boolean <span title="dom-area-noHref">noHref</span>;
};</pre>
<p>The <dfn title="dom-area-noHref"><code>noHref</code></dfn> IDL
attribute of the <code>area</code> element must <span>reflect</span>
the element's <code title="attr-area-nohref">nohref</code> content
attribute.</p>
<hr>
<p>The <code>basefont</code> element must implement the
<code>HTMLBaseFontElement</code> interface.</p>
<pre class="idl">interface <dfn>HTMLBaseFontElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-basefont-color">color</span>;
attribute DOMString <span title="dom-basefont-face">face</span>;
attribute long <span title="dom-basefont-size">size</span>; <!-- yes, long, not DOMString (so says DOM2 HTML) -->
};</pre>
<p>The <dfn title="dom-basefont-color"><code>color</code></dfn>,
<dfn title="dom-basefont-face"><code>face</code></dfn>, and <dfn
title="dom-basefont-size"><code>size</code></dfn> IDL attributes of
the <code>basefont</code> element must <span>reflect</span> the
respective content attributes of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLBodyElement</span> {
attribute DOMString <span title="dom-body-text">text</span>;
attribute DOMString <span title="dom-body-bgColor">bgColor</span>;
attribute DOMString <span title="dom-body-background">background</span>;
attribute DOMString <span title="dom-body-link">link</span>;
attribute DOMString <span title="dom-body-vLink">vLink</span>;
attribute DOMString <span title="dom-body-aLink">aLink</span>;
};</pre>
<p>The <dfn title="dom-body-text"><code>text</code></dfn> IDL
attribute of the <code>body</code> element must <span>reflect</span>
the element's <code title="attr-body-text">text</code> content
attribute.</p>
<p>The <dfn title="dom-body-bgColor"><code>bgColor</code></dfn> IDL
attribute of the <code>body</code> element must <span>reflect</span>
the element's <code title="attr-body-bgcolor">bgcolor</code> content
attribute.</p>
<p>The <dfn
title="dom-body-background"><code>background</code></dfn> IDL
attribute of the <code>body</code> element must <span>reflect</span>
the element's <code title="attr-body-background">background</code>
content attribute. (The <code
title="attr-body-background">background</code> content is
<em>not</em> defined to contain a <span>URL</span>, despite rules
regarding its handling in the rendering section above.)</p>
<p>The <dfn title="dom-body-link"><code>link</code></dfn> IDL
attribute of the <code>body</code> element must <span>reflect</span>
the element's <code title="attr-body-link">link</code> content
attribute.</p>
<p>The <dfn title="dom-body-aLink"><code>aLink</code></dfn> IDL
attribute of the <code>body</code> element must <span>reflect</span>
the element's <code title="attr-body-alink">alink</code> content
attribute.</p>
<p>The <dfn title="dom-body-vLink"><code>vLink</code></dfn> IDL
attribute of the <code>body</code> element must <span>reflect</span>
the element's <code title="attr-body-vlink">vlink</code> content
attribute.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLBRElement</span> {
attribute DOMString <span title="dom-br-clear">clear</span>;
};</pre>
<p>The <dfn title="dom-br-clear"><code>clear</code></dfn> IDL
attribute of the <code>br</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLTableCaptionElement</span> {
attribute DOMString <span title="dom-caption-align">align</span>;
};</pre>
<p>The <dfn title="dom-caption-align"><code>align</code></dfn> IDL
attribute of the <code>caption</code> element must
<span>reflect</span> the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLTableColElement</span> {
attribute DOMString <span title="dom-col-align">align</span>;
attribute DOMString <span title="dom-col-ch">ch</span>;
attribute DOMString <span title="dom-col-chOff">chOff</span>;
attribute DOMString <span title="dom-col-vAlign">vAlign</span>;
attribute DOMString <span title="dom-col-width">width</span>;
};</pre>
<p>The <dfn title="dom-col-align"><code>align</code></dfn> and <dfn
title="dom-col-width"><code>width</code></dfn> IDL attributes of
the <code>col</code> element must <span>reflect</span> the
respective content attributes of the same name.</p>
<p>The <dfn title="dom-col-ch"><code>ch</code></dfn> IDL attribute
of the <code>col</code> element must <span>reflect</span> the
element's <code title="attr-col-char">char</code> content
attribute.</p>
<p>The <dfn title="dom-col-chOff"><code>chOff</code></dfn> IDL
attribute of the <code>col</code> element must <span>reflect</span>
the element's <code title="attr-col-charoff">charoff</code> content
attribute.</p>
<p>The <dfn title="dom-col-vAlign"><code>vAlign</code></dfn> IDL
attribute of the <code>col</code> element must <span>reflect</span>
the element's <code title="attr-col-valign">valign</code> content
attribute.</p>
<hr>
<p>User agents must treat <code>dir</code> elements in a manner
equivalent to <code>ul</code> elements.</p>
<p>The <code>dir</code> element must implement the
<code>HTMLDirectoryElement</code> interface.</p>
<pre class="idl">interface <dfn>HTMLDirectoryElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-dir-compact">compact</span>;
};</pre>
<p>The <dfn title="dom-dir-compact"><code>compact</code></dfn> IDL
attribute of the <code>dir</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLDivElement</span> {
attribute DOMString <span title="dom-div-align">align</span>;
};</pre>
<p>The <dfn title="dom-div-align"><code>align</code></dfn> IDL
attribute of the <code>div</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLDListElement</span> {
attribute DOMString <span title="dom-dl-compact">compact</span>;
};</pre>
<p>The <dfn title="dom-dl-compact"><code>compact</code></dfn> IDL
attribute of the <code>dl</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLEmbedElement</span> {
attribute DOMString <span title="dom-embed-align">align</span>;
attribute DOMString <span title="dom-embed-name">name</span>;
};</pre>
<p>The <dfn title="dom-embed-name"><code>name</code></dfn> and <dfn
title="dom-embed-align"><code>align</code></dfn> IDL attributes of
the <code>embed</code> element must <span>reflect</span> the
respective content attributes of the same name.</p>
<hr>
<p>The <code>font</code> element must implement the
<code>HTMLFontElement</code> interface.</p>
<pre class="idl">interface <dfn>HTMLFontElement</dfn> : <span>HTMLElement</span> {
attribute DOMString <span title="dom-font-color">color</span>;
attribute DOMString <span title="dom-font-face">face</span>;
attribute DOMString <span title="dom-font-size">size</span>; <!-- yes, DOMString, not long (so says DOM2 HTML) -->
};</pre>
<p>The <dfn title="dom-font-color"><code>color</code></dfn>,
<dfn title="dom-font-face"><code>face</code></dfn>, and <dfn
title="dom-font-size"><code>size</code></dfn> IDL attributes of
the <code>font</code> element must <span>reflect</span> the
respective content attributes of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLHeadingElement</span> {
attribute DOMString <span title="dom-hx-align">align</span>;
};</pre>
<p>The <dfn title="dom-hx-align"><code>align</code></dfn> IDL
attribute of the <code>h1</code>–<code>h6</code> elements must
<span>reflect</span> the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLHeadElement</span> {
attribute DOMString <span title="dom-head-profile">profile</span>;
};</pre>
<p>User agents should ignore the <code
title="attr-head-profile">profile</code> content attribute on
<code>head</code> elements.</p>
<p>When the attribute would be used as a list of <span
title="URL">URLs</span> identifying metadata profiles, the user
agent should instead always assume that all known profiles apply to
all pages, and should therefore apply the conventions of all known
metadata profiles to the document, ignoring the value of the
attribute.</p>
<p>When the attribute's value would be handled as a list of <span
title="URL">URLs</span> to be dereferenced, the user agent must use
the following steps:</p>
<ol>
<li><p><span title="split a string on spaces">Split on
spaces</span> the value of the <code
title="attr-head-profile">profile</code> attribute.</p></li>
<li><p><span title="resolve a url">Resolve</span> each resulting
token relative to the <code>head</code> element.</p></li>
<li><p>For each token that is successfully resolved,
<span>fetch</span> the resulting <span>absolute URL</span> and
apply the appropriate processing.</p></li> <!-- http-origin privacy
sensitive -->
</ol>
<p>The <dfn title="dom-head-profile"><code>profile</code></dfn> IDL
attribute of the <code>head</code> element must <span>reflect</span>
the content attribute of the same name, as if the attribute's value
was just a string. (In other words, the value is not <span
title="resolve a url">resolved</span> in any way on getting.)</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLHRElement</span> {
attribute DOMString <span title="dom-hr-align">align</span>;
attribute boolean <span title="dom-hr-noShade">noShade</span>;
attribute DOMString <span title="dom-hr-size">size</span>;
attribute DOMString <span title="dom-hr-width">width</span>;
};</pre>
<p>The <dfn title="dom-hr-align"><code>align</code></dfn>, <dfn
title="dom-hr-size"><code>size</code></dfn>, and <dfn
title="dom-hr-width"><code>width</code></dfn> IDL attributes of the
<code>hr</code> element must <span>reflect</span> the respective
content attributes of the same name.</p>
<p>The <dfn title="dom-hr-noShade"><code>noShade</code></dfn> IDL
attribute of the <code>hr</code> element must <span>reflect</span>
the element's <code title="attr-input-noshade">noshade</code>
content attribute.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLHtmlElement</span> {
attribute DOMString <span title="dom-html-version">version</span>;
};</pre>
<p>The <dfn title="dom-html-version"><code>version</code></dfn> IDL
attribute of the <code>html</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLIFrameElement</span> {
attribute DOMString <span title="dom-iframe-align">align</span>;
attribute DOMString <span title="dom-iframe-frameBorder">frameBorder</span>;
attribute DOMString <span title="dom-iframe-longDesc">longDesc</span>;
attribute DOMString <span title="dom-iframe-marginHeight">marginHeight</span>;
attribute DOMString <span title="dom-iframe-marginWidth">marginWidth</span>;
attribute DOMString <span title="dom-iframe-scrolling">scrolling</span>;
};</pre>
<p>The <dfn title="dom-iframe-align"><code>align</code></dfn> and
<dfn title="dom-iframe-scrolling"><code>scrolling</code></dfn> IDL
attributes of the <code>iframe</code> element must
<span>reflect</span> the respective content attributes of the same
name.</p>
<p>The <dfn
title="dom-iframe-frameBorder"><code>frameBorder</code></dfn> IDL
attribute of the <code>iframe</code> element must
<span>reflect</span> the element's <code
title="attr-iframe-iframeborder">iframeborder</code> content
attribute.</p>
<p>The <dfn title="dom-iframe-longDesc"><code>longDesc</code></dfn>
IDL attribute of the <code>iframe</code> element must
<span>reflect</span> the element's <code
title="attr-iframe-longdesc">longdesc</code> content attribute.</p>
<p>The <dfn
title="dom-iframe-marginHeight"><code>marginHeight</code></dfn> IDL
attribute of the <code>iframe</code> element must
<span>reflect</span> the element's <code
title="attr-iframe-marginheight">marginheight</code> content
attribute.</p>
<p>The <dfn
title="dom-iframe-marginWidth"><code>marginWidth</code></dfn> IDL
attribute of the <code>iframe</code> element must
<span>reflect</span> the element's <code
title="attr-iframe-marginwidth">marginwidth</code> content
attribute.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLImageElement</span> {
attribute DOMString <span title="dom-img-name">name</span>;
attribute DOMString <span title="dom-img-align">align</span>;
attribute DOMString <span title="dom-img-border">border</span>;
attribute unsigned long <span title="dom-img-hspace">hspace</span>;
attribute DOMString <span title="dom-img-longDesc">longDesc</span>;
attribute unsigned long <span title="dom-img-vspace">vspace</span>;
};</pre>
<p>The <dfn title="dom-img-name"><code>name</code></dfn>, <dfn
title="dom-img-align"><code>align</code></dfn>, <dfn
title="dom-img-border"><code>border</code></dfn>, <dfn
title="dom-img-hspace"><code>hspace</code></dfn>, and <dfn
title="dom-img-vspace"><code>vspace</code></dfn> IDL attributes of
the <code>img</code> element must <span>reflect</span> the
respective content attributes of the same name.</p>
<p>The <dfn title="dom-img-longDesc"><code>longDesc</code></dfn> IDL
attribute of the <code>img</code> element must <span>reflect</span>
the element's <code title="attr-img-longdesc">longdesc</code> content
attribute.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLInputElement</span> {
attribute DOMString <span title="dom-input-align">align</span>;
attribute DOMString <span title="dom-input-useMap">useMap</span>;
};</pre>
<p>The <dfn title="dom-input-align"><code>align</code></dfn> IDL
attribute of the <code>input</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<p>The <dfn title="dom-input-useMap"><code>useMap</code></dfn> IDL
attribute of the <code>input</code> element must
<span>reflect</span> the element's <code
title="attr-input-usemap">usemap</code> content attribute.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLLegendElement</span> {
attribute DOMString <span title="dom-legend-align">align</span>;
};</pre>
<p>The <dfn title="dom-legend-align"><code>align</code></dfn> IDL
attribute of the <code>legend</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLLIElement</span> {
attribute DOMString <span title="dom-li-type">type</span>;
};</pre>
<p>The <dfn title="dom-li-type"><code>type</code></dfn> IDL
attribute of the <code>li</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLLinkElement</span> {
attribute DOMString <span title="dom-link-charset">charset</span>;
attribute DOMString <span title="dom-link-rev">rev</span>;
attribute DOMString <span title="dom-link-target">target</span>;
};</pre>
<p>The <dfn title="dom-link-charset"><code>charset</code></dfn>,
<dfn title="dom-link-rev"><code>rev</code></dfn>, and <dfn
title="dom-link-target"><code>target</code></dfn> IDL attributes of
the <code>link</code> element must <span>reflect</span> the
respective content attributes of the same name.</p>
<hr>
<p>User agents must treat <code>listing</code> elements in a manner
equivalent to <code>pre</code> elements.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLMenuElement</span> {
attribute DOMString <span title="dom-menu-compact">compact</span>;
};</pre>
<p>The <dfn title="dom-menu-compact"><code>compact</code></dfn> IDL
attribute of the <code>menu</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLMetaElement</span> {
attribute DOMString <span title="dom-meta-scheme">scheme</span>;
};</pre>
<p>User agents may treat the <code
title="attr-meta-scheme">scheme</code> content attribute on the
<code>meta</code> element as an extension of the element's <code
title="attr-meta-name">name</code> content attribute when processing
a <code>meta</code> element with a <code
title="attr-meta-name">name</code> attribute whose value is one that
the user agent recognises as supporting the <code
title="attr-meta-scheme">scheme</code> attribute.</p>
<p>User agents are encouraged to ignore the <code
title="attr-meta-scheme">scheme</code> attribute and instead process
the value given to the metadata name as if it had been specified for
each expected value of the <code
title="attr-meta-scheme">scheme</code> attribute.</p>
<div class="example">
<p>For example, if the user agent acts on <code>meta</code>
elements with <code title="attr-meta-name">name</code> attributes
having the value "eGMS.subject.keyword", and knows that the <code
title="attr-meta-scheme">scheme</code> attribute is used with this
metadata name, then it could take the <code
title="attr-meta-scheme">scheme</code> attribute into account,
acting as if it was an extension of the <code
title="attr-meta-name">name</code> attribute. Thus the following
two <code>meta</code> elements could be treated as two elements
giving values for two different metadata names, one consisting of a
combination of "eGMS.subject.keyword" and "LGCL", and the other
consisting of a combination of "eGMS.subject.keyword" and
"ORLY":</p>
<pre class="bad"><!-- this markup is invalid -->
<meta name="eGMS.subject.keyword" scheme="LGCL" content="Abandoned vehicles">
<meta name="eGMS.subject.keyword" scheme="ORLY" content="Mah car: kthxbye"></pre>
<p>The recommended processing of this markup, however, would be
equivalent to the following:</p>
<pre><meta name="eGMS.subject.keyword" content="Abandoned vehicles">
<meta name="eGMS.subject.keyword" content="Mah car: kthxbye"></pre>
</div>
<p>The <dfn title="dom-meta-scheme"><code>scheme</code></dfn> IDL
attribute of the <code>meta</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLObjectElement</span> {
attribute DOMString <span title="dom-object-align">align</span>;
attribute DOMString <span title="dom-object-archive">archive</span>;
attribute DOMString <span title="dom-object-border">border</span>;
attribute DOMString <span title="dom-object-code">code</span>;
attribute DOMString <span title="dom-object-codeBase">codeBase</span>;
attribute DOMString <span title="dom-object-codeType">codeType</span>;
attribute boolean <span title="dom-object-declare">declare</span>;
attribute unsigned long <span title="dom-object-hspace">hspace</span>;
attribute DOMString <span title="dom-object-standby">standby</span>;
attribute unsigned long <span title="dom-object-vspace">vspace</span>;
};</pre>
<p>The <dfn title="dom-object-align"><code>align</code></dfn>, <dfn
title="dom-object-archive"><code>archive</code></dfn>, <dfn
title="dom-object-border"><code>border</code></dfn>, <dfn
title="dom-object-code"><code>code</code></dfn>, <dfn
title="dom-object-declare"><code>declare</code></dfn>, <dfn
title="dom-object-hspace"><code>hspace</code></dfn>, <dfn
title="dom-object-standby"><code>standby</code></dfn>, and <dfn
title="dom-object-vspace"><code>vspace</code></dfn> IDL attributes
of the <code>object</code> element must <span>reflect</span> the
respective content attributes of the same name.</p>
<p>The <dfn title="dom-object-codeBase"><code>codeBase</code></dfn> IDL
attribute of the <code>object</code> element must <span>reflect</span>
the element's <code title="attr-object-codebase">codebase</code> content
attribute.</p>
<p>The <dfn title="dom-object-codeType"><code>codeType</code></dfn> IDL
attribute of the <code>object</code> element must <span>reflect</span>
the element's <code title="attr-object-codetype">codetype</code> content
attribute.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLOListElement</span> {
attribute DOMString <span title="dom-ol-compact">compact</span>;
attribute DOMString <span title="dom-ol-type">type</span>;
};</pre>
<p>The <dfn title="dom-ol-compact"><code>compact</code></dfn> and
<dfn title="dom-ol-type"><code>type</code></dfn> IDL attributes of
the <code>ol</code> element must <span>reflect</span> the respective
content attributes of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLParagraphElement</span> {
attribute DOMString <span title="dom-p-align">align</span>;
};</pre>
<p>The <dfn title="dom-p-align"><code>align</code></dfn> IDL
attribute of the <code>p</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLParamElement</span> {
attribute DOMString <span title="dom-param-type">type</span>;
attribute DOMString <span title="dom-param-valueType">valueType</span>;
};</pre>
<p>The <dfn title="dom-param-type"><code>type</code></dfn> IDL
attribute of the <code>param</code> element must
<span>reflect</span> the content attribute of the same name.</p>
<p>The <dfn title="dom-param-valueType"><code>valueType</code></dfn>
IDL attribute of the <code>param</code> element must
<span>reflect</span> the element's <code
title="attr-param-valuetype">valuetype</code> content attribute.</p>
<hr>
<p>User agents must treat <code>plaintext</code> elements in a
manner equivalent to <code>pre</code> elements.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLPreElement</span> {
attribute unsigned long <span title="dom-pre-width">width</span>;
};</pre>
<p>The <dfn title="dom-pre-width"><code>width</code></dfn> IDL
attribute of the <code>pre</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLScriptElement</span> {
attribute DOMString <span title="dom-script-event">event</span>;
attribute DOMString <span title="dom-script-htmlFor">htmlFor</span>;
};</pre>
<p>The <dfn title="dom-script-event"><code>event</code></dfn> and
<dfn title="dom-script-htmlFor"><code>htmlFor</code></dfn> IDL
attributes of the <code>script</code> element must return the empty
string on getting, and do nothing on setting.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLTableElement</span> {
attribute DOMString <span title="dom-table-align">align</span>;
attribute DOMString <span title="dom-table-bgColor">bgColor</span>;
attribute DOMString <span title="dom-table-border">border</span>;
attribute DOMString <span title="dom-table-cellPadding">cellPadding</span>;
attribute DOMString <span title="dom-table-cellSpacing">cellSpacing</span>;
attribute DOMString <span title="dom-table-frame">frame</span>;
attribute DOMString <span title="dom-table-rules">rules</span>;
attribute DOMString <span title="dom-table-width">width</span>;
};</pre>
<p>The <dfn title="dom-table-align"><code>align</code></dfn>, <dfn
title="dom-table-border"><code>border</code></dfn>, <dfn
title="dom-table-frame"><code>frame</code></dfn>, <dfn
title="dom-table-rules"><code>rules</code></dfn>, and <dfn
title="dom-table-width"><code>width</code></dfn>, IDL attributes of
the <code>table</code> element must <span>reflect</span> the
respective content attributes of the same name.</p>
<p>The <dfn title="dom-table-bgColor"><code>bgColor</code></dfn> IDL
attribute of the <code>table</code> element must <span>reflect</span>
the element's <code title="attr-table-bgcolor">bgcolor</code> content
attribute.</p>
<p>The <dfn title="dom-table-cellPadding"><code>cellPadding</code></dfn> IDL
attribute of the <code>table</code> element must <span>reflect</span>
the element's <code title="attr-table-cellpadding">cellpadding</code> content
attribute.</p>
<p>The <dfn title="dom-table-cellSpacing"><code>cellSpacing</code></dfn> IDL
attribute of the <code>table</code> element must <span>reflect</span>
the element's <code title="attr-table-cellspacing">cellspacing</code> content
attribute.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLTableSectionElement</span> {
attribute DOMString <span title="dom-tbody-align">align</span>;
attribute DOMString <span title="dom-tbody-ch">ch</span>;
attribute DOMString <span title="dom-tbody-chOff">chOff</span>;
attribute DOMString <span title="dom-tbody-vAlign">vAlign</span>;
};</pre>
<p>The <dfn title="dom-tbody-align"><code>align</code></dfn> IDL
attribute of the <code>tbody</code>, <code>thead</code>, and
<code>tfoot</code> elements must <span>reflect</span> the content
attribute of the same name.</p>
<p>The <dfn title="dom-tbody-ch"><code>ch</code></dfn> IDL attribute
of the <code>tbody</code>, <code>thead</code>, and
<code>tfoot</code> elements must <span>reflect</span> the elements'
<code title="attr-tbody-char">char</code> content attributes.</p>
<p>The <dfn title="dom-tbody-chOff"><code>chOff</code></dfn> IDL
attribute of the <code>tbody</code>, <code>thead</code>, and
<code>tfoot</code> elements must <span>reflect</span> the elements'
<code title="attr-tbody-charoff">charoff</code> content attributes.</p>
<p>The <dfn title="dom-tbody-vAlign"><code>vAlign</code></dfn> IDL
attribute of the <code>tbody</code>, <code>thead</code>, and
<code>tfoot</code> element must <span>reflect</span> the elements'
<code title="attr-tbody-valign">valign</code> content
attributes.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLTableCellElement</span> {
attribute DOMString <span title="dom-tdth-abbr">abbr</span>;
attribute DOMString <span title="dom-tdth-align">align</span>;
attribute DOMString <span title="dom-tdth-axis">axis</span>;
attribute DOMString <span title="dom-tdth-bgColor">bgColor</span>;
attribute DOMString <span title="dom-tdth-ch">ch</span>;
attribute DOMString <span title="dom-tdth-chOff">chOff</span>;
attribute DOMString <span title="dom-tdth-height">height</span>;
attribute boolean <span title="dom-tdth-noWrap">noWrap</span>;
attribute DOMString <span title="dom-tdth-vAlign">vAlign</span>;
attribute DOMString <span title="dom-tdth-width">width</span>;
};</pre>
<p>The <dfn title="dom-tdth-abbr"><code>abbr</code></dfn>, <dfn
title="dom-tdth-align"><code>align</code></dfn>, <dfn
title="dom-tdth-axis"><code>axis</code></dfn>, <dfn
title="dom-tdth-height"><code>height</code></dfn>, and <dfn
title="dom-tdth-width"><code>width</code></dfn> IDL attributes of
the <code>td</code> and <code>th</code> elements must
<span>reflect</span> the respective content attributes of the same
name.</p>
<p>The <dfn title="dom-tdth-bgColor"><code>bgColor</code></dfn> IDL
attribute of the <code>td</code> and <code>th</code> elements must
<span>reflect</span> the elements' <code
title="attr-tdth-bgcolor">bgcolor</code> content attributes.</p>
<p>The <dfn title="dom-tdth-ch"><code>ch</code></dfn> IDL
attribute of the <code>td</code> and <code>th</code> elements must
<span>reflect</span> the elements' <code
title="attr-tdth-char">char</code> content attributes.</p>
<p>The <dfn title="dom-tdth-chOff"><code>chOff</code></dfn> IDL
attribute of the <code>td</code> and <code>th</code> elements must
<span>reflect</span> the elements' <code
title="attr-tdth-charoff">charoff</code> content attributes.</p>
<p>The <dfn title="dom-tdth-noWrap"><code>noWrap</code></dfn> IDL
attribute of the <code>td</code> and <code>th</code> elements must
<span>reflect</span> the elements' <code
title="attr-tdth-nowrap">nowrap</code> content attributes.</p>
<p>The <dfn title="dom-tdth-vAlign"><code>vAlign</code></dfn> IDL
attribute of the <code>td</code> and <code>th</code> element must
<span>reflect</span> the elements' <code
title="attr-tdth-valign">valign</code> content attributes.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLTableRowElement</span> {
attribute DOMString <span title="dom-tr-align">align</span>;
attribute DOMString <span title="dom-tr-bgColor">bgColor</span>;
attribute DOMString <span title="dom-tr-ch">ch</span>;
attribute DOMString <span title="dom-tr-chOff">chOff</span>;
attribute DOMString <span title="dom-tr-vAlign">vAlign</span>;
};</pre>
<p>The <dfn title="dom-tr-align"><code>align</code></dfn> IDL
attribute of the <code>tr</code> element must <span>reflect</span>
the content attribute of the same name.</p>
<p>The <dfn title="dom-tr-bgColor"><code>bgColor</code></dfn> IDL
attribute of the <code>tr</code> element must <span>reflect</span>
the element's <code title="attr-tr-bgcolor">bgcolor</code> content
attribute.</p>
<p>The <dfn title="dom-tr-ch"><code>ch</code></dfn> IDL attribute of
the <code>tr</code> element must <span>reflect</span> the element's
<code title="attr-tr-char">char</code> content attribute.</p>
<p>The <dfn title="dom-tr-chOff"><code>chOff</code></dfn> IDL
attribute of the <code>tr</code> element must <span>reflect</span>
the element's <code title="attr-tr-charoff">charoff</code> content
attribute.</p>
<p>The <dfn title="dom-tr-vAlign"><code>vAlign</code></dfn> IDL
attribute of the <code>tr</code> element must <span>reflect</span>
the element's <code title="attr-tr-valign">valign</code> content
attribute.</p>
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLUListElement</span> {
attribute DOMString <span title="dom-ul-compact">compact</span>;
attribute DOMString <span title="dom-ul-type">type</span>;
};</pre>
<p>The <dfn title="dom-ul-compact"><code>compact</code></dfn> and
<dfn title="dom-ul-type"><code>type</code></dfn> IDL attributes of
the <code>ul</code> element must <span>reflect</span> the respective
content attributes of the same name.</p>
<hr>
<p>User agents must treat <code>xmp</code> elements in a manner
equivalent to <code>pre</code> elements.</p>
<hr>
<p>The <code>isindex</code>, <code>nextid</code>, <code>rb</code>,
and <code>spacer</code> elements must use the
<code>HTMLUnknownElement</code> interface.</p> <!-- has to be
explicitly listed because technically we define the elements in the
spec, albeit as obsolete, and then we say that only elements not
defined in this spec use HTMLUnknownElement. -->
<hr>
<pre class="idl">[Supplemental]
interface <span>HTMLDocument</span> {
attribute DOMString <span title="dom-document-fgColor">fgColor</span>;
attribute DOMString <span title="dom-document-bgColor">bgColor</span>;
attribute DOMString <span title="dom-document-linkColor">linkColor</span>;
attribute DOMString <span title="dom-document-vlinkColor">vlinkColor</span>;
attribute DOMString <span title="dom-document-alinkColor">alinkColor</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-document-anchors">anchors</span>;
readonly attribute <span>HTMLCollection</span> <span title="dom-document-applets">applets</span>;
readonly attribute <span>HTMLAllCollection</span> <span title="dom-document-all">all</span>;
};</pre>
<p>The attributes of the <code>Document</code> object listed in the
first column of the following table must <span>reflect</span> the
content attribute on <span>the body element</span> with the name
given in the corresponding cell in the second column on the same
row, if <span>the body element</span> is a <code>body</code> element
(as opposed to a <code>frameset</code> element). When there is no
<span title="the body element">body element</span> or if it is a
<code>frameset</code> element, the attributes must instead return
the empty string on getting and do nothing on setting.</p>
<table>
<thead>
<tr>
<th> IDL attribute
<th> Content attribute
<tbody>
<tr>
<td><dfn title="dom-document-fgColor"><code>fgColor</code></dfn>
<td><code title="attr-body-text">text</code>
<tr>
<td><dfn title="dom-document-bgColor"><code>bgColor</code></dfn>
<td><code title="attr-body-bgcolor">bgcolor</code>
<tr>
<td><dfn title="dom-document-linkColor"><code>linkColor</code></dfn>
<td><code title="attr-body-link">link</code>
<tr>
<td><dfn title="dom-document-vLinkColor"><code>vLinkColor</code></dfn>
<td><code title="attr-body-vlink">vlink</code>
<tr>
<td><dfn title="dom-document-aLinkColor"><code>aLinkColor</code></dfn>
<td><code title="attr-body-alink">alink</code>
</table>
<hr>
<p>The <dfn title="dom-document-anchors"><code>anchors</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only <code>a</code>
elements with <code title="attr-a-name">name</code>
attributes.</p>
<p>The <dfn title="dom-document-applets"><code>applets</code></dfn>
attribute must return an <code>HTMLCollection</code> rooted at the
<code>Document</code> node, whose filter matches only
<code>applet</code> elements.</p>
<hr>
<p>The <dfn title="dom-document-all"><code>all</code></dfn>
attribute must return an <code>HTMLAllCollection</code> rooted at the
<code>Document</code> node, whose filter matches all elements.</p>
<p>The object returned for <code title="dom-document-all">all</code>
has several unusual behaviors:</p>
<ul>
<li><p>The user agent must act as if the ToBoolean() operator in
JavaScript converts the object returned for <code
title="dom-document-all">all</code> to the false value.</p></li>
<li><p>The user agent must act as if, for the purposes of the <code
title="">==</code> and <code title="">!=</code> operators in
JavaScript, the object returned for <code
title="dom-document-all">all</code> is equal to the <code
title="">undefined</code> value.</p></li>
<li><p>The user agent must act such that the <code
title="">typeof</code> operator in JavaScript returns the string
<code title="">undefined</code> when applied to the object returned
for <code title="dom-document-all">all</code>.</p></li>
</ul>
<p class="note">These requirements are a <span>willful
violation</span> of the JavaScript specification current at the time
of writing (ECMAScript edition 3). The JavaScript specification
requires that the ToBoolean() operator convert all objects to the
true value, and does not have provisions for objects acting as if
they were <code title="">undefined</code> for the purposes of
certain operators. This violation is motivated by a desire for
compatibility with two classes of legacy content: one that uses the
presence of <code title="dom-document-all">document.all</code> as a
way to detect legacy user agents, and one that only supports those
legacy user agents and uses the <code
title="dom-document-all">document.all</code> object without testing
for its presence first. <a href="#refsECMA262">[ECMA262]</a></p>
</div>
<h2 id="iana">IANA considerations</h2>
<!-- http://www.w3.org/2002/06/registering-mediatype.html -->
<h3><dfn><code>text/html</code></dfn></h3>
<p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p>
<!--
To: ietf-types@iana.org
Subject: Registration of media type text/html
-->
<!--
Obsoletes:
http://www.ietf.org/rfc/rfc2854
Include a request to retire RFC 2854 persuant to section 6.4 of RFC 2026.
-->
<dl>
<dt>Type name:</dt>
<dd>text</dd>
<dt>Subtype name:</dt>
<dd>html</dd>
<dt>Required parameters:</dt>
<dd>No required parameters</dd>
<dt>Optional parameters:</dt>
<dd>
<dl>
<dt><code title="">charset</code></dt>
<dd>
<p>The <code title="">charset</code> parameter may be provided
to definitively specify the <span>document's character
encoding</span>, overriding any <span title="character encoding
declaration">character encoding declarations</span> in the
document. The parameter's value must be the name of the
character encoding used to serialize the file, must be a valid
character encoding name, and must be an <span>ASCII
case-insensitive</span> match for the <span>preferred MIME
name</span> for that encoding. <a
href="#refsIANACHARSET">[IANACHARSET]</a></p>
</dd>
</dl>
</dd>
<dt>Encoding considerations:</dt>
<dd>See the section on <span title="character encoding
declaration">character encoding declarations</span>.</dd>
<dt>Security considerations:</dt>
<dd>
<p>Entire novels have been written about the security
considerations that apply to HTML documents. Many are listed in
this document, to which the reader is referred for more
details. Some general concerns bear mentioning here, however:</p>
<p>HTML is scripted language, and has a large number of APIs (some
of which are described in this document). Script can expose the
user to potential risks of information leakage, credential
leakage, cross-site scripting attacks, cross-site request
forgeries, and a host of other problems. While the designs in this
specification are intended to be safe if implemented correctly, a
full implementation is a massive undertaking and, as with any
software, user agents are likely to have security bugs.</p>
<p>Even without scripting, there are specific features in HTML
which, for historical reasons, are required for broad
compatibility with legacy content but that expose the user to
unfortunate security problems. In particular, the <code>img</code>
element can be used in conjunction with some other features as a
way to effect a port scan from the user's location on the
Internet. This can expose local network topologies that the
attacker would otherwise not be able to determine.</p>
</dd>
<dt>Interoperability considerations:</dt>
<dd>
Rules for processing both conforming and non-conforming content
are defined in this specification.
</dd>
<dt>Published specification:</dt>
<dd>
This document is the relevant specification. Labeling a resource
with the <code>text/html</code> type asserts that the resource is
an <span title="HTML documents">HTML document</span> using
<span>the HTML syntax</span>.
</dd>
<dt>Applications that use this media type:</dt>
<dd>
Web browsers, tools for processing Web content, HTML authoring
tools, search engines, validators.
</dd>
<dt>Additional information:</dt>
<dd>
<dl>
<dt>Magic number(s):</dt>
<dd>No sequence of bytes can uniquely identify an HTML
document. More information on detecting HTML documents is
available in the Content-Type Processing Model specification. <a
href="#refsMIMESNIFF">[MIMESNIFF]</a></dd>
<dt>File extension(s):</dt>
<dd>"<code title="">html</code>" and "<code title="">htm</code>"
are commonly, but certainly not exclusively, used as the
extension for HTML documents.</dd>
<dt>Macintosh file type code(s):</dt>
<dd><code title="">TEXT</code></dd>
</dl>
</dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>No restrictions apply.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C and WHATWG</dd>
</dl>
<p>Fragment identifiers used with <code>text/html</code> resources
refer to <span>the indicated part of the document</span>.</p>
<h3><dfn><code>application/xhtml+xml</code></dfn></h3>
<p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p>
<!--
To: ietf-types@iana.org
Subject: Registration of media type application/xhtml+xml
-->
<!--
Obsoletes:
http://www.ietf.org/rfc/rfc3236.txt
-->
<dl>
<dt>Type name:</dt>
<dd>application</dd>
<dt>Subtype name:</dt>
<dd>xhtml+xml</dd>
<dt>Required parameters:</dt>
<dd>Same as for <code>application/xml</code> <a href="#refsRFC3023">[RFC3023]</a></dd>
<dt>Optional parameters:</dt>
<dd>Same as for <code>application/xml</code> <a href="#refsRFC3023">[RFC3023]</a></dd>
<dt>Encoding considerations:</dt>
<dd>Same as for <code>application/xml</code> <a href="#refsRFC3023">[RFC3023]</a></dd>
<dt>Security considerations:</dt>
<dd>Same as for <code>application/xml</code> <a href="#refsRFC3023">[RFC3023]</a></dd>
<dt>Interoperability considerations:</dt>
<dd>Same as for <code>application/xml</code> <a href="#refsRFC3023">[RFC3023]</a></dd>
<dt>Published specification:</dt>
<dd>
Labeling a resource with the <code>application/xhtml+xml</code>
type asserts that the resource is an XML document that likely has
a root element from the <span>HTML namespace</span>. As such, the
relevant specifications are the XML specification, the Namespaces
in XML specification, and this specification. <a
href="#refsXML">[XML]</a> <a href="#refsXMLNS">[XMLNS]</a>
</dd>
<dt>Applications that use this media type:</dt>
<dd>Same as for <code>application/xml</code> <a href="#refsRFC3023">[RFC3023]</a></dd>
<dt>Additional information:</dt>
<dd>
<dl>
<dt>Magic number(s):</dt>
<dd>Same as for <code>application/xml</code> <a href="#refsRFC3023">[RFC3023]</a></dd>
<dt>File extension(s):</dt>
<dd>"<code title="">xhtml</code>" and "<code title="">xht</code>"
are sometimes used as extensions for XML resources that have a
root element from the <span>HTML namespace</span>.</dd>
<dt>Macintosh file type code(s):</dt>
<dd><code title="">TEXT</code></dd>
</dl>
</dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>No restrictions apply.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C and WHATWG</dd>
</dl>
<p>Fragment identifiers used with <code>application/xhtml+xml</code>
resources have the same semantics as with any <span>XML MIME
type</span>. <a href="#refsRFC3023">[RFC3023]</a></p>
<h3><dfn><code>text/cache-manifest</code></dfn></h3>
<p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p>
<!--
To: ietf-types@iana.org
Subject: Registration of media type text/cache-manifest
-->
<dl>
<dt>Type name:</dt>
<dd>text</dd>
<dt>Subtype name:</dt>
<dd>cache-manifest</dd>
<dt>Required parameters:</dt>
<dd>No parameters</dd>
<dt>Optional parameters:</dt>
<dd>No parameters</dd>
<dt>Encoding considerations:</dt>
<dd>Always UTF-8.</dd>
<dt>Security considerations:</dt>
<dd>
<p>Cache manifests themselves pose no immediate risk unless
sensitive information is included within the
manifest. Implementations, however, are required to follow
specific rules when populating a cache based on a cache manifest,
to ensure that certain origin-based restrictions are
honored. Failure to correctly implement these rules can result in
information leakage, cross-site scripting attacks, and the
like.</p>
</dd>
<dt>Interoperability considerations:</dt>
<dd>
Rules for processing both conforming and non-conforming content
are defined in this specification.
</dd>
<dt>Published specification:</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Applications that use this media type:</dt>
<dd>
Web browsers.
</dd>
<dt>Additional information:</dt>
<dd>
<dl>
<dt>Magic number(s):</dt>
<dd>Cache manifests begin with the string "<code title="">CACHE
MANIFEST</code>", followed by either a U+0020 SPACE character, a
U+0009 CHARACTER TABULATION (tab) character, a U+000A LINE FEED
(LF) character, or a U+000D CARRIAGE RETURN (CR) character.</dd>
<dt>File extension(s):</dt>
<dd>"<code title="">manifest</code>"</dd>
<dt>Macintosh file type code(s):</dt>
<dd>No specific Macintosh file type codes are recommended for this type.</dd>
</dl>
</dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>No restrictions apply.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C and WHATWG</dd>
</dl>
<p>Fragment identifiers have no meaning with
<code>text/cache-manifest</code> resources.</p>
<h3><dfn><code>text/ping</code></dfn></h3>
<p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p>
<!--
To: ietf-types@iana.org
Subject: Registration of media type text/ping
-->
<dl>
<dt>Type name:</dt>
<dd>text</dd>
<dt>Subtype name:</dt>
<dd>ping</dd>
<dt>Required parameters:</dt>
<dd>No parameters</dd>
<dt>Optional parameters:</dt>
<dd>No parameters</dd>
<dt>Encoding considerations:</dt>
<dd>Not applicable.</dd>
<dt>Security considerations:</dt>
<dd>
<p>If used exclusively in the fashion described in the context of
<span>hyperlink auditing</span>, this type introduces no new
security concerns.</p>
</dd>
<dt>Interoperability considerations:</dt>
<dd>
Rules applicable to this type are defined in this specification.
</dd>
<dt>Published specification:</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Applications that use this media type:</dt>
<dd>
Web browsers.
</dd>
<dt>Additional information:</dt>
<dd>
<dl>
<dt>Magic number(s):</dt>
<dd><code>text/ping</code> resources always consist of the four
bytes 0x50 0x49 0x4E 0x47 (ASCII 'PING').</dd>
<dt>File extension(s):</dt>
<dd>No specific file extension is recommended for this type.</dd>
<dt>Macintosh file type code(s):</dt>
<dd>No specific Macintosh file type codes are recommended for this type.</dd>
</dl>
</dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>Only intended for use with HTTP POST requests generated as part
of a Web browser's processing of the <code
title="attr-hyperlink-ping">ping</code> attribute.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C and WHATWG</dd>
</dl>
<p>Fragment identifiers have no meaning with
<code>text/ping</code> resources.</p>
<h3><dfn><code>application/microdata+json</code></dfn></h3>
<p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p>
<!--
To: ietf-types@iana.org
Subject: Registration of media type application/microdata+json
-->
<dl>
<dt>Type name:</dt>
<dd>application</dd>
<dt>Subtype name:</dt>
<dd>microdata+json</dd>
<dt>Required parameters:</dt>
<dd>Same as for <code>application/json</code> <a href="#refsJSON">[JSON]</a></dd>
<dt>Optional parameters:</dt>
<dd>Same as for <code>application/json</code> <a href="#refsJSON">[JSON]</a></dd>
<dt>Encoding considerations:</dt>
<dd>Always UTF-8.</dd>
<dt>Security considerations:</dt>
<dd>Same as for <code>application/json</code> <a href="#refsJSON">[JSON]</a></dd>
<dt>Interoperability considerations:</dt>
<dd>Same as for <code>application/json</code> <a href="#refsJSON">[JSON]</a></dd>
<dt>Published specification:</dt>
<dd>
Labeling a resource with the
<code>application/microdata+json</code> type asserts that the
resource is a JSON text that consists of an object with a single
entry called "<code title="">items</code>" consisting of an array
of entries, each of which consists of an object with two entries,
one called "<code title="">type</code>" whose value is an array of
strings, and one called "<code title="">properties</code>" whose
value is an object whose entries each have a value consisting of
an array of either objects or strings, the objects being of the
same form as the objects in the aforementioned "<code
title="">items</code>" entry. As such, the relevant specifications
are the JSON specification and this specification. <a
href="#refsJSON">[JSON]</a>
</dd>
<dt>Applications that use this media type:</dt>
<dd>Same as for <code>application/json</code> <a href="#refsJSON">[JSON]</a></dd>
<dt>Additional information:</dt>
<dd>
<dl>
<dt>Magic number(s):</dt>
<dd>Same as for <code>application/json</code> <a href="#refsJSON">[JSON]</a></dd>
<dt>File extension(s):</dt>
<dd>Same as for <code>application/json</code> <a href="#refsJSON">[JSON]</a></dd>
<dt>Macintosh file type code(s):</dt>
<dd>Same as for <code>application/json</code> <a href="#refsJSON">[JSON]</a></dd>
</dl>
</dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>No restrictions apply.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C and WHATWG</dd>
</dl>
<p>Fragment identifiers used with
<code>application/microdata+json</code> resources have the same
semantics as when used with <code>application/json</code>. <a
href="#refsJSON">[JSON]</a></p>
<h3><dfn title="http-ping-from"><code>Ping-From</code></dfn></h3>
<p>This section describes a header field for registration in the
Permanent Message Header Field Registry. <a
href="#refsRFC3864">[RFC3864]</a></p>
<dl>
<dt>Header field name</dt>
<dd>Ping-From</dd>
<dt>Applicable protocol</dt>
<dd>http</dd>
<dt>Status</dt>
<dd>standard</dd>
<dt>Author/Change controller</dt>
<dd>W3C and WHATWG</dd>
<dt>Specification document(s)</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Related information</dt>
<dd>None.</dd>
</dl>
<h3><dfn title="http-ping-to"><code>Ping-To</code></dfn></h3>
<p>This section describes a header field for registration in the
Permanent Message Header Field Registry. <a
href="#refsRFC3864">[RFC3864]</a></p>
<dl>
<dt>Header field name</dt>
<dd>Ping-To</dd>
<dt>Applicable protocol</dt>
<dd>http</dd>
<dt>Status</dt>
<dd>standard</dd>
<dt>Author/Change controller</dt>
<dd>W3C and WHATWG</dd>
<dt>Specification document(s)</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Related information</dt>
<dd>None.</dd>
</dl>
<h2 id="index" class="no-num">Index</h2>
<div class="impl">
<p>The following sections only cover conforming elements and features.</p>
</div>
<h3 class="no-num">Elements</h3>
<p><i>This section is non-normative.</i></p>
<table>
<caption>List of elements</caption>
<thead>
<tr>
<th> Element
<th> Description
<th> Categories
<th> Parents
<th> Children
<th> Attributes
<th> Interface
<tbody>
<tr>
<th><code>a</code></th>
<td>Hyperlink</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>*;
<span title="Interactive content">interactive</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span>transparent</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-hyperlink-href">href</code>;
<code title="attr-hyperlink-target">target</code>;
<code title="attr-hyperlink-ping">ping</code>;
<code title="attr-hyperlink-rel">rel</code>;
<code title="attr-hyperlink-media">media</code>;
<code title="attr-hyperlink-hreflang">hreflang</code>;
<code title="attr-hyperlink-type">type</code></td>
<td><code>HTMLAnchorElement</code></td>
</tr>
<tr>
<th><code>abbr</code></th>
<td>Abbreviation</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>address</code></th>
<td>Contact information for a page or section</td>
<td><span title="Flow content">flow</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span>*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>area</code></th>
<td>Hyperlink or dead area on an image map</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span>*</td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-area-alt">alt</code>;
<code title="attr-area-coords">coords</code>;
<code title="attr-area-shape">shape</code>;
<code title="attr-hyperlink-href">href</code>;
<code title="attr-hyperlink-target">target</code>;
<code title="attr-hyperlink-ping">ping</code>;
<code title="attr-hyperlink-rel">rel</code>;
<code title="attr-hyperlink-media">media</code>;
<code title="attr-hyperlink-hreflang">hreflang</code>;
<code title="attr-hyperlink-type">type</code></td>
<td><code>HTMLAreaElement</code></td>
</tr>
<tr>
<th><code>article</code></th>
<td>Self-contained syndicatable or reusable composition</td>
<td><span title="Flow content">flow</span>;
<span title="Sectioning content">sectioning</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>aside</code></th>
<td>Sidebar for tangentially related content</td>
<td><span title="Flow content">flow</span>;
<span title="Sectioning content">sectioning</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>audio</code></th>
<td>Audio player</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Embedded content">embedded</span>;
<span title="Interactive content">interactive</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><code>source</code>*;
<span>transparent</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-media-src">src</code>;
<code title="attr-media-autobuffer">autobuffer</code>;
<code title="attr-media-autoplay">autoplay</code>;
<code title="attr-media-loop">loop</code>;
<code title="attr-media-controls">controls</code></td>
<td><code>HTMLAudioElement</code></td>
</tr>
<tr>
<th><code>b</code></th>
<td>Keywords</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>base</code></th>
<td>Base URL and default target <span>browsing context</span> for <span title="attr-hyperlink-target">hyperlinks</span> and <span title="attr-fs-target">forms</span></td>
<td><span title="Metadata content">metadata</span></td>
<td><code>head</code></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-base-href">href</code>;
<code title="attr-base-target">target</code></td>
<td><code>HTMLBaseElement</code></td>
</tr>
<tr>
<th><code>bdo</code></th>
<td>Text directionality formatting</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>blockquote</code></th>
<td>A section quoted from another source</td>
<td><span title="Flow content">flow</span>;
<span title="Sectioning root">sectioning root</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-blockquote-cite">cite</code></td>
<td><code>HTMLQuoteElement</code></td>
</tr>
<tr>
<th><code>body</code></th>
<td>Document body</td>
<td><span title="Sectioning root">sectioning root</span></td>
<td><code>html</code></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span>;
<code title="handler-window-onafterprint">onafterprint</code>;
<code title="handler-window-onbeforeprint">onbeforeprint</code>;
<code title="handler-window-onbeforeunload">onbeforeunload</code>;
<code title="handler-window-onblur">onblur</code>;
<code title="handler-window-onerror">onerror</code>;
<code title="handler-window-onfocus">onfocus</code>;
<code title="handler-window-onhashchange">onhashchange</code>;
<code title="handler-window-onload">onload</code>;
<code title="handler-window-onmessage">onmessage</code>;
<code title="handler-window-onoffline">onoffline</code>;
<code title="handler-window-ononline">ononline</code>;
<code title="handler-window-onpagehide">onpagehide</code>;
<code title="handler-window-onpageshow">onpageshow</code>;
<code title="handler-window-onpopstate">onpopstate</code>;
<code title="handler-window-onredo">onredo</code>;
<code title="handler-window-onresize">onresize</code>;
<code title="handler-window-onstorage">onstorage</code>;
<code title="handler-window-onundo">onundo</code>;
<code title="handler-window-onunload">onunload</code></td>
<td><code>HTMLBodyElement</code></td>
</tr>
<tr>
<th><code>br</code></th>
<td>Line break, e.g. in poem or postal address</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td>empty</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLBRElement</code></td>
</tr>
<tr>
<th><code>button</code></th>
<td>Button control</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Interactive content">interactive</span>;
<span title="category-listed">Listed</span>;
<span title="category-label">labelable</span>;
<span title="category-submit">submittable</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span>Phrasing content</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-fe-autofocus">autofocus</code>;
<code title="attr-fe-disabled">disabled</code>;
<code title="attr-fae-form">form</code>;
<code title="attr-fs-formaction">formaction</code>;
<code title="attr-fs-formenctype">formenctype</code>;
<code title="attr-fs-formmethod">formmethod</code>;
<code title="attr-fs-formnovalidate">formnovalidate</code>;
<code title="attr-fs-formtarget">formtarget</code>;
<code title="attr-fe-name">name</code>;
<code title="attr-button-type">type</code>;
<code title="attr-button-value">value</code></td>
<td><code>HTMLButtonElement</code></td>
</tr>
<tr>
<th><code>canvas</code></th>
<td>Scriptable bitmap canvas</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Embedded content">embedded</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span>transparent</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-canvas-width">width</code>;
<code title="attr-canvas-height">height</code></td>
<td><code>HTMLCanvasElement</code></td>
</tr>
<tr>
<th><code>caption</code></th>
<td>Table caption</td>
<td>none</td>
<td><code>table</code></td>
<td><span title="Flow content">flow</span>*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLTableCaptionElement</code></td>
</tr>
<tr>
<th><code>cite</code></th>
<td>Title of a work</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>code</code></th>
<td>Computer code</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>col</code></th>
<td>Table column</td>
<td>none</td>
<td><code>colgroup</code></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-col-span">span</code></td>
<td><code>HTMLTableColElement</code></td>
</tr>
<tr>
<th><code>colgroup</code></th>
<td>Group of columns in a table</td>
<td>none</td>
<td><code>table</code></td>
<td><code>col</code></td>
<td><span title="global attributes">globals</span>;
<code title="attr-colgroup-span">span</code></td>
<td><code>HTMLTableColElement</code></td>
</tr>
<tr>
<th><code>command</code></th>
<td>Menu command</td>
<td><span title="Metadata content">metadata</span>;
<span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><code>head</code>;
<span title="Phrasing content">phrasing</span></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-command-type">type</code>;
<code title="attr-command-label">label</code>;
<code title="attr-command-icon">icon</code>;
<code title="attr-command-disabled">disabled</code>;
<code title="attr-command-checked">checked</code>;
<code title="attr-command-radiogroup">radiogroup</code></td>
<td><code>HTMLCommandElement</code></td>
</tr>
<tr>
<th><code>datalist</code></th>
<td>Container for options for <span title="attr-input-list">combo box control</span></td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span>;
<code>option</code></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLDataListElement</code></td>
</tr>
<tr>
<th><code>dd</code></th>
<td>Content for corresponding <code>dt</code> element(s)</td>
<td>none</td>
<td><code>dl</code>;
<code>figure</code>;
<code>details</code></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>del</code></th>
<td>A removal from the document</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>*</td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span>transparent</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-mod-cite">cite</code>;
<code title="attr-mod-datetime">datetime</code></td>
<td><code>HTMLModElement</code></td>
</tr>
<tr>
<th><code>details</code></th>
<td>Disclosure control for hiding details</td>
<td><span title="Flow content">flow</span>;
<span title="Sectioning root">sectioning root</span>;
<span title="Interactive content">interactive</span></td>
<td><span title="Flow content">flow</span></td>
<td><code>dt</code>*;
<code>dd</code>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-details-open">open</code></td>
<td><code>HTMLDetailsElement</code></td>
</tr>
<tr>
<th><code>dfn</code></th>
<td>Defining instance</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span>*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>div</code></th>
<td>Generic flow container</td>
<td><span title="Flow content">flow</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLDivElement</code></td>
</tr>
<tr>
<th><code>dl</code></th>
<td>Association list consisting of zero or more name-value groups</td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><code>dt</code>*;
<code>dd</code>*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLDListElement</code></td>
</tr>
<tr>
<th><code>dt</code></th>
<td>Legend for corresponding <code>dd</code> element(s)</td>
<td>none</td>
<td><code>dl</code>;
<code>figure</code>;
<code>details</code></td>
<td>varies*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>em</code></th>
<td>Stress emphasis</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>embed</code></th>
<td><span>Plugin</span></td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Embedded content">embedded</span>;
<span title="Interactive content">interactive</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-embed-src">src</code>;
<code title="attr-embed-type">type</code>;
<code title="attr-dim-width">width</code>;
<code title="attr-dim-height">height</code>;
any*</td>
<td><code>HTMLEmbedElement</code></td>
</tr>
<tr>
<th><code>fieldset</code></th>
<td>Group of form controls</td>
<td><span title="Flow content">flow</span>;
<span title="Sectioning root">sectioning root</span>;
<span title="category-listed">listed</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Flow content">flow</span></td>
<td><code>legend</code>*;
<span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-fieldset-disabled">disabled</code>;
<code title="attr-fae-form">form</code>;
<code title="attr-fe-name">name</code></td>
<td><code>HTMLFieldSetElement</code></td>
</tr>
<tr>
<th><code>figure</code></th>
<td>Figure with optional caption</td>
<td><span title="Flow content">flow</span>;
<span title="Sectioning root">sectioning root</span></td>
<td><span title="Flow content">flow</span></td>
<td><code>dt</code>*;
<code>dd</code>*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>footer</code></th>
<td>Footer for a page or section</td>
<td><span title="Flow content">flow</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span>*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>form</code></th>
<td>User-submittable form</td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-form-accept-charset">accept-charset</code>;
<code title="attr-fs-action">action</code>;
<code title="attr-form-autocomplete">autocomplete</code>;
<code title="attr-fs-enctype">enctype</code>;
<code title="attr-fs-method">method</code>;
<code title="attr-form-name">name</code>;
<code title="attr-fs-novalidate">novalidate</code>;
<code title="attr-fs-target">target</code></td>
<td><code>HTMLFormElement</code></td>
</tr>
<tr>
<th><code>h1</code>, <code>h2</code>, <code>h3</code>, <code>h4</code>, <code>h5</code>, <code>h6</code></th>
<td>Section heading</td>
<td><span title="Flow content">flow</span>;
<span title="Heading content">heading</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><code>hgroup</code>;
<span title="Flow content">flow</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLHeadingElement</code></td>
</tr>
<tr>
<th><code>head</code></th>
<td>Container for document metadata</td>
<td>none</td>
<td><code>html</code></td>
<td><span title="Metadata content">metadata content</span>*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLHeadElement</code></td>
</tr>
<tr>
<th><code>header</code></th>
<td>Introductory or navigational aids for a page or section</td>
<td><span title="Flow content">flow</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span>*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>hgroup</code></th>
<td>heading group</td>
<td><span title="Flow content">flow</span>;
<span title="Heading content">heading</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td>One or more <code>h1</code>, <code>h2</code>, <code>h3</code>, <code>h4</code>, <code>h5</code>, and/or <code>h6</code></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>hr</code></th>
<td>Thematic break</td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td>empty</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLHRElement</code></td>
</tr>
<tr>
<th><code>html</code></th>
<td>Root element</td>
<td>none</td>
<td>none*</td>
<td><code>head</code>*;
<code>body</code>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-html-manifest">manifest</code></td>
<td><code>HTMLHtmlElement</code></td>
</tr>
<tr>
<th><code>i</code></th>
<td>Alternate voice</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>iframe</code></th>
<td><span>Nested browsing context</span></td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Embedded content">embedded</span>;
<span title="Interactive content">interactive</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td>text*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-iframe-src">src</code>;
<code title="attr-iframe-name">name</code>;
<code title="attr-iframe-sandbox">sandbox</code>;
<code title="attr-iframe-seamless">seamless</code>;
<code title="attr-dim-width">width</code>;
<code title="attr-dim-height">height</code></td>
<td><code>HTMLIFrameElement</code></td>
</tr>
<tr>
<th><code>img</code></th>
<td>Image</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Embedded content">embedded</span>;
<span title="Interactive content">interactive</span>*</td>
<td><span title="Phrasing content">phrasing</span></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-img-alt">alt</code>;
<code title="attr-img-src">src</code>;
<code title="attr-hyperlink-usemap">usemap</code>;
<code title="attr-img-ismap">ismap</code>;
<code title="attr-dim-width">width</code>;
<code title="attr-dim-height">height</code></td>
<td><code>HTMLImageElement</code></td>
</tr>
<tr>
<th><code>input</code></th>
<td>Form control</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Interactive content">interactive</span>*;
<span title="category-listed">listed</span>;
<span title="category-label">labelable</span>;
<span title="category-submit">submittable</span>;
<span title="category-reset">resettable</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-input-accept">accept</code>;
<code title="attr-input-alt">alt</code>;
<code title="attr-input-autocomplete">autocomplete</code>;
<code title="attr-fe-autofocus">autofocus</code>;
<code title="attr-input-checked">checked</code>;
<code title="attr-fe-disabled">disabled</code>;
<code title="attr-fae-form">form</code>;
<code title="attr-fs-formaction">formaction</code>;
<code title="attr-fs-formenctype">formenctype</code>;
<code title="attr-fs-formmethod">formmethod</code>;
<code title="attr-fs-formnovalidate">formnovalidate</code>;
<code title="attr-fs-formtarget">formtarget</code>;
<code title="attr-dim-height">height</code>;
<code title="attr-input-list">list</code>;
<code title="attr-input-max">max</code>;
<code title="attr-input-maxlength">maxlength</code>;
<code title="attr-input-min">min</code>;
<code title="attr-input-multiple">multiple</code>;
<code title="attr-fe-name">name</code>;
<code title="attr-input-pattern">pattern</code>;
<code title="attr-input-placeholder">placeholder</code>;
<code title="attr-input-readonly">readonly</code>;
<code title="attr-input-required">required</code>;
<code title="attr-input-size">size</code>;
<code title="attr-input-src">src</code>;
<code title="attr-input-step">step</code>;
<code title="attr-input-type">type</code>;
<code title="attr-input-value">value</code>;
<code title="attr-dim-width">width</code></td>
<td><code>HTMLInputElement</code></td>
</tr>
<tr>
<th><code>ins</code></th>
<td>An addition to the document</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>*</td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span>transparent</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-mod-cite">cite</code>;
<code title="attr-mod-datetime">datetime</code></td>
<td><code>HTMLModElement</code></td>
</tr>
<tr>
<th><code>kbd</code></th>
<td>User input</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>keygen</code></th>
<td>Cryptographic key-pair generator form control</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Interactive content">interactive</span>;
<span title="category-listed">listed</span>;
<span title="category-label">labelable</span>;
<span title="category-submit">submittable</span>;
<span title="category-reset">resettable</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-fe-autofocus">autofocus</code>;
<code title="attr-keygen-challenge">challenge</code>;
<code title="attr-fe-disabled">disabled</code>;
<code title="attr-fae-form">form</code>;
<code title="attr-keygen-keytype">keytype</code>;
<code title="attr-fe-name">name</code></td>
<td><code>HTMLKeygenElement</code></td>
</tr>
<tr>
<th><code>label</code></th>
<td>Caption for a form control</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Interactive content">interactive</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-fae-form">form</code>;
<code title="attr-label-for">for</code></td>
<td><code>HTMLLabelElement</code></td>
</tr>
<tr>
<th><code>legend</code></th>
<td>Caption for <code>fieldset</code></td>
<td>none</td>
<td><code>fieldset</code></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLLegendElement</code></td>
</tr>
<tr>
<th><code>li</code></th>
<td>List item</td>
<td>none</td>
<td><code>ol</code>; <code>ul</code>; <code>menu</code></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-li-value">value</code>*</td>
<td><code>HTMLLIElement</code></td>
</tr>
<tr>
<th><code>link</code></th>
<td>Link metadata</td>
<td><span title="Metadata content">metadata</span>;
<span title="Flow content">flow</span>*;
<span title="Phrasing content">phrasing</span>*</td>
<td><code>head</code>;
<code>noscript</code>*;
<span title="phrasing content">phrasing</span>*</td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-link-href">href</code>;
<code title="attr-link-rel">rel</code>;
<code title="attr-link-media">media</code>;
<code title="attr-link-hreflang">hreflang</code>;
<code title="attr-link-type">type</code>;
<code title="attr-link-sizes">sizes</code></td>
<td><code>HTMLLinkElement</code></td>
</tr>
<tr>
<th><code>map</code></th>
<td><span>Image map</span></td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>*</td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span>transparent</span>;
<code>area</code>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-map-name">name</code></td>
<td><code>HTMLMapElement</code></td>
</tr>
<tr>
<th><code>mark</code></th>
<td>Highlight</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>menu</code></th>
<td>Menu of commands</td>
<td><span title="Flow content">flow</span>;
<span title="Interactive content">interactive</span>*</td>
<td><span title="Flow content">flow</span></td>
<td><code>li</code>*;
<span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-menu-type">type</code>;
<code title="attr-menu-label">label</code></td>
<td><code>HTMLMenuElement</code></td>
</tr>
<tr>
<th><code>meta</code></th>
<td>Text metadata</td>
<td><span title="Metadata content">metadata</span>;
<span title="Flow content">flow</span>*;
<span title="Phrasing content">phrasing</span>*</td>
<td><code>head</code>;
<code>noscript</code>*;
<span title="phrasing content">phrasing</span>*</td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-meta-name">name</code>;
<code title="attr-meta-http-equiv">http-equiv</code>;
<code title="attr-meta-content">content</code>;
<code title="attr-meta-charset">charset</code></td>
<td><code>HTMLMetaElement</code></td>
</tr>
<tr>
<th><code>meter</code></th>
<td>Gauge</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-meter-value">value</code>;
<code title="attr-meter-min">min</code>;
<code title="attr-meter-low">low</code>;
<code title="attr-meter-high">high</code>;
<code title="attr-meter-max">max</code>;
<code title="attr-meter-optimum">optimum</code></td>
<td><code>HTMLMeterElement</code></td>
</tr>
<tr>
<th><code>nav</code></th>
<td>Section with navigational links</td>
<td><span title="Flow content">flow</span>;
<span title="Sectioning content">sectioning</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>noscript</code></th>
<td>Fallback content for script</td>
<td><span title="Metadata content">metadata</span>;
<span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><code>head</code>*;
<span title="Phrasing content">phrasing</span>*</td>
<td>varies*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>object</code></th>
<td>Image, <span>nested browsing context</span>, or <span>plugin</span></td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Embedded content">embedded</span>;
<span title="Interactive content">interactive</span>*;
<span title="category-listed">listed</span>;
<span title="category-submit">submittable</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><code>param</code>*;
<span>transparent</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-object-data">data</code>;
<code title="attr-object-type">type</code>;
<code title="attr-object-name">name</code>;
<code title="attr-hyperlink-usemap">usemap</code>;
<code title="attr-fae-form">form</code>;
<code title="attr-dim-width">width</code>;
<code title="attr-dim-height">height</code></td>
<td><code>HTMLObjectElement</code></td>
</tr>
<tr>
<th><code>ol</code></th>
<td>Ordered list</td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><code>li</code></td>
<td><span title="global attributes">globals</span>;
<code title="attr-ol-reversed">reversed</code>;
<code title="attr-ol-start">start</code></td>
<td><code>HTMLOListElement</code></td>
</tr>
<tr>
<th><code>optgroup</code></th>
<td>Group of options in a list box</td>
<td>none</td>
<td><code>select</code></td>
<td><code>option</code></td>
<td><span title="global attributes">globals</span>;
<code title="attr-optgroup-disabled">disabled</code>;
<code title="attr-optgroup-label">label</code></td>
<td><code>HTMLOptGroupElement</code></td>
</tr>
<tr>
<th><code>option</code></th>
<td>Option in a list box or combo box control</td>
<td>none</td>
<td><code>select</code>;
<code>datalist</code>;
<code>optgroup</code></td>
<td><span title="text content">text</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-option-disabled">disabled</code>;
<code title="attr-option-label">label</code>;
<code title="attr-option-selected">selected</code>;
<code title="attr-option-value">value</code></td>
<td><code>HTMLOptionElement</code></td>
</tr>
<tr>
<th><code>output</code></th>
<td>Calculated output value</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="category-listed">listed</span>;
<span title="category-reset">resettable</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-output-for">for</code>;
<code title="attr-fae-form">form</code>;
<code title="attr-fe-name">name</code></td>
<td><code>HTMLOutputElement</code></td>
</tr>
<tr>
<th><code>p</code></th>
<td>Paragraph</td>
<td><span title="Flow content">flow</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLParagraphElement</code></td>
</tr>
<tr>
<th><code>param</code></th>
<td>Parameter for <code>object</code></td>
<td>none</td>
<td><code>object</code></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-param-name">name</code>;
<code title="attr-param-value">value</code></td>
<td><code>HTMLParamElement</code></td>
</tr>
<tr>
<th><code>pre</code></th>
<td>Block of preformatted text</td>
<td><span title="Flow content">flow</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLPreElement</code></td>
</tr>
<tr>
<th><code>progress</code></th>
<td>Progress bar</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-progress-value">value</code>;
<code title="attr-progress-max">max</code></td>
<td><code>HTMLProgressElement</code></td>
</tr>
<tr>
<th><code>q</code></th>
<td>Quotation</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-q-cite">cite</code></td>
<td><code>HTMLQuoteElement</code></td>
</tr>
<tr>
<th><code>rp</code></th>
<td>Parenthesis for ruby annotation text</td>
<td>none</td>
<td><code>ruby</code></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>rt</code></th>
<td>Ruby annotation text</td>
<td>none</td>
<td><code>ruby</code></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>ruby</code></th>
<td>Ruby annotation(s)</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span>;
<code>rt</code> element;
<code>rp</code> element*</td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>samp</code></th>
<td>Computer output</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>script</code></th>
<td>Embedded script</td>
<td><span title="Metadata content">metadata</span>;
<span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><code>head</code>;
<span title="Phrasing content">phrasing</span></td>
<td>script, data, or script documentation*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-script-src">src</code>;
<code title="attr-script-async">async</code>;
<code title="attr-script-defer">defer</code>;
<code title="attr-script-type">type</code>;
<code title="attr-script-charset">charset</code></td>
<td><code>HTMLScriptElement</code></td>
</tr>
<tr>
<th><code>section</code></th>
<td>Generic document or application section</td>
<td><span title="Flow content">flow</span>;
<span title="Sectioning content">sectioning</span>;
<span title="formatBlock candidate"><code title="">formatBlock</code> candidate</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>select</code></th>
<td>List box control</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Interactive content">interactive</span>;
<span title="category-listed">listed</span>;
<span title="category-label">labelable</span>;
<span title="category-submit">submittable</span>;
<span title="category-reset">resettable</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><code>option</code>, <code>optgroup</code></td>
<td><span title="global attributes">globals</span>;
<code title="attr-fe-autofocus">autofocus</code>;
<code title="attr-fe-disabled">disabled</code>;
<code title="attr-fae-form">form</code>;
<code title="attr-select-multiple">multiple</code>;
<code title="attr-fe-name">name</code>;
<code title="attr-select-size">size</code></td>
<td><code>HTMLSelectElement</code></td>
</tr>
<tr>
<th><code>small</code></th>
<td>Side comment</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>source</code></th>
<td>Media source for <code>video</code> or <code>audio</code></td>
<td>none</td>
<td><code>video</code>;
<code>audio</code></td>
<td>empty</td>
<td><span title="global attributes">globals</span>;
<code title="attr-source-src">src</code>;
<code title="attr-source-type">type</code>;
<code title="attr-source-media">media</code></td>
<td><code>HTMLSourceElement</code></td>
</tr>
<tr>
<th><code>span</code></th>
<td>Generic phrasing container</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLSpanElement</code></td>
</tr>
<tr>
<th><code>strong</code></th>
<td>Importance</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>style</code></th>
<td>Embedded styling information</td>
<td><span title="Metadata content">metadata</span>;
<span title="Flow content">flow</span></td>
<td><code>head</code>;
<code>noscript</code>*;
<span title="flow content">flow</span>*</td>
<td>varies*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-style-media">media</code>;
<code title="attr-style-type">type</code>;
<code title="attr-style-scoped">scoped</code></td>
<td><code>HTMLStyleElement</code></td>
</tr>
<tr>
<th><code>sub</code></th>
<td>Subscript</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>sup</code></th>
<td>Superscript</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>table</code></th>
<td>Table</td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><code>caption</code>*;
<code>colgroup</code>*;
<code>thead</code>*;
<code>tbody</code>*;
<code>tfoot</code>*;
<code>tr</code>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-table-summary">summary</code></td>
<td><code>HTMLTableElement</code></td>
</tr>
<tr>
<th><code>tbody</code></th>
<td>Group of rows in a table</td>
<td>none</td>
<td><code>table</code></td>
<td><code>tr</code></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLTableSectionElement</code></td>
</tr>
<tr>
<th><code>td</code></th>
<td>Table cell</td>
<td><span title="Sectioning root">sectioning root</span></td>
<td><code>tr</code></td>
<td><span title="Flow content">flow</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-tdth-colspan">colspan</code>;
<code title="attr-tdth-rowspan">rowspan</code>;
<code title="attr-tdth-headers">headers</code></td>
<td><code>HTMLTableDataCellElement</code></td>
</tr>
<tr>
<th><code>textarea</code></th>
<td>Multiline text field</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Interactive content">interactive</span>;
<span title="category-listed">listed</span>;
<span title="category-label">labelable</span>;
<span title="category-submit">submittable</span>;
<span title="category-reset">resettable</span>;
<span title="Form-associated element">form-associated</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="text content">text</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-fe-autofocus">autofocus</code>;
<code title="attr-textarea-cols">cols</code>;
<code title="attr-fe-disabled">disabled</code>;
<code title="attr-fae-form">form</code>;
<code title="attr-textarea-maxlength">maxlength</code>;
<code title="attr-fe-name">name</code>;
<code title="attr-textarea-placeholder">placeholder</code>;
<code title="attr-textarea-readonly">readonly</code>;
<code title="attr-textarea-required">required</code>;
<code title="attr-textarea-rows">rows</code>;
<code title="attr-textarea-wrap">wrap</code></td>
<td><code>HTMLTextAreaElement</code></td>
</tr>
<tr>
<th><code>tfoot</code></th>
<td>Group of footer rows in a table</td>
<td>none</td>
<td><code>table</code></td>
<td><code>tr</code></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLTableSectionElement</code></td>
</tr>
<tr>
<th><code>th</code></th>
<td>Table header cell</td>
<td>none</td>
<td><code>tr</code></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span>;
<code title="attr-tdth-colspan">colspan</code>;
<code title="attr-tdth-rowspan">rowspan</code>;
<code title="attr-tdth-headers">headers</code>;
<code title="attr-th-scope">scope</code></td>
<td><code>HTMLTableHeaderCellElement</code></td>
</tr>
<tr>
<th><code>thead</code></th>
<td>Group of heading rows in a table</td>
<td>none</td>
<td><code>table</code></td>
<td><code>tr</code></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLTableSectionElement</code></td>
</tr>
<tr>
<th><code>time</code></th>
<td>Date and/or time</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-time-datetime">datetime</code>;
<code title="attr-time-pubdate">pubdate</code></td>
<td><code>HTMLTimeElement</code></td>
</tr>
<tr>
<th><code>title</code></th>
<td>Document title</td>
<td><span title="Metadata content">metadata</span></td>
<td><code>head</code></td>
<td><span title="text content">text</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLTitleElement</code></td>
</tr>
<tr>
<th><code>tr</code></th>
<td>Table row</td>
<td>none</td>
<td><code>table</code>;
<code>thead</code>;
<code>tbody</code>;
<code>tfoot</code></td>
<td><code>th</code>*;
<code>td</code></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLTableRowElement</code></td>
</tr>
<tr>
<th><code>ul</code></th>
<td>List</td>
<td><span title="Flow content">flow</span></td>
<td><span title="Flow content">flow</span></td>
<td><code>li</code></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLUListElement</code></td>
</tr>
<tr>
<th><code>var</code></th>
<td>Variable</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><span title="global attributes">globals</span></td>
<td><code>HTMLElement</code></td>
</tr>
<tr>
<th><code>video</code></th>
<td>Video player</td>
<td><span title="Flow content">flow</span>;
<span title="Phrasing content">phrasing</span>;
<span title="Embedded content">embedded</span>;
<span title="Interactive content">interactive</span></td>
<td><span title="Phrasing content">phrasing</span></td>
<td><code>source</code>*;
<span>transparent</span>*</td>
<td><span title="global attributes">globals</span>;
<code title="attr-media-src">src</code>;
<code title="attr-video-poster">poster</code>;
<code title="attr-media-autobuffer">autobuffer</code>;
<code title="attr-media-autoplay">autoplay</code>;
<code title="attr-media-loop">loop</code>;
<code title="attr-media-controls">controls</code>;
<code title="attr-dim-width">width</code>;
<code title="attr-dim-height">height</code></td>
<td><code>HTMLVideoElement</code></td>
</tr>
</table>
<p>An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.</p>
<h3 class="no-num">Attributes</h3>
<p><i>This section is non-normative.</i></p>
<table>
<caption>List of attributes (excluding event handler content attributes)</caption>
<thead>
<tr>
<th> Attribute
<th> Element(s)
<th> Description
<th> Value
<tbody>
<tr>
<th> <code title="">accept</code>
<td> <code title="attr-input-accept">input</code>
<td> Hint for expected file type in <span title="attr-input-type-file">file upload controls</span>
<td> <span>Set of comma-separated tokens</span>* consisting of <span title="valid MIME type">valid MIME types</span> or <code title="">audio/*</code>, <code title="">video/*</code>, or <code title="">image/*</code>
<tr>
<th> <code title="">accept-charset</code>
<td> <code title="attr-form-accept-charset">form</code>
<td> Character encodings to use for <span>form submission</span>
<td> <span>Ordered set of unique space-separated tokens</span> consisting of <span title="preferred MIME name">preferred MIME names</span> of <span title="ASCII-compatible character encoding">ASCII-compatible character encodings</span>*
<tr>
<th> <code title="">accesskey</code>
<td> <span title="attr-accesskey">HTML elements</span>
<td> Keyboard shortcut to activate or focus element
<td> <span>Ordered set of unique space-separated tokens</span> consisting of one Unicode code point in length
<tr>
<th> <code title="">action</code>
<td> <code title="attr-fs-action">form</code>
<td> <span>URL</span> to use for <span>form submission</span>
<td> <span>Valid URL</span>
<tr>
<th> <code title="">alt</code>
<td> <code title="attr-area-alt">area</code>;
<code title="attr-img-alt">img</code>;
<code title="attr-input-alt">input</code>
<td> Replacement text for use when images are not available
<td> Text*
<tr>
<th> <code title="">async</code>
<td> <code title="attr-script-async">script</code>
<td> Execute script asynchronously
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">autobuffer</code>
<td> <code title="attr-media-autobuffer">audio</code>;
<code title="attr-media-autobuffer">video</code>
<td> Hint that buffering the <span>media resource</span> will likely be needed
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">autocomplete</code>
<td> <code title="attr-form-autocomplete">form</code>;
<code title="attr-input-autocomplete">input</code>
<td> Prevent the user agent from providing autocompletions for the form control(s)
<td> "<code title="">on</code>"; "<code title="">off</code>"
<tr>
<th> <code title="">autofocus</code>
<td> <code title="attr-fe-autofocus">button</code>;
<code title="attr-fe-autofocus">input</code>;
<code title="attr-fe-autofocus">keygen</code>;
<code title="attr-fe-autofocus">select</code>;
<code title="attr-fe-autofocus">textarea</code>
<td> Automatically focus the form control when the page is loaded
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">autoplay</code>
<td> <code title="attr-media-autoplay">audio</code>;
<code title="attr-media-autoplay">video</code>
<td> Hint that the <span>media resource</span> can be started automatically when the page is loaded
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">challenge</code>
<td> <code title="attr-keygen-challenge">keygen</code>
<td> String to package with the generated and signed public key
<td> Text
<tr>
<th> <code title="">charset</code>
<td> <code title="attr-meta-charset">meta</code>
<td> <span>Character encoding declaration</span>
<td> <span>Preferred MIME name</span> of an encoding*
<tr>
<th> <code title="">charset</code>
<td> <code title="attr-script-charset">script</code>
<td> Character encoding of the external script resource
<td> <span>Preferred MIME name</span> of an encoding*
<tr>
<th> <code title="">checked</code>
<td> <code title="attr-command-checked">command</code>;
<code title="attr-input-checked">input</code>
<td> Whether the command or control is checked
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">cite</code>
<td> <code title="attr-blockquote-cite">blockquote</code>;
<code title="attr-mod-cite">del</code>;
<code title="attr-mod-cite">ins</code>;
<code title="attr-q-cite">q</code>
<td> Link to the source of the quotation or more information about the edit
<td> <span>Valid URL</span>
<tr>
<th> <code title="">class</code>
<td> <span title="attr-class">HTML elements</span>
<td> Classes to which the element belongs
<td> <span>Unordered set of unique space-separated tokens</span>
<tr>
<th> <code title="">cols</code>
<td> <code title="attr-textarea-cols">textarea</code>
<td> Maximum number of characters per line
<td> <span>Valid non-negative integer</span> greater than zero
<tr>
<th> <code title="">colspan</code>
<td> <code title="attr-tdth-colspan">td</code>;
<code title="attr-tdth-colspan">th</code>
<td> Number of columns that the cell is to span
<td> <span>Valid non-negative integer</span> greater than zero
<tr>
<th> <code title="">content</code>
<td> <code title="attr-meta-content">meta</code>
<td> Value of the element
<td> Text*
<tr>
<th> <code title="">contenteditable</code>
<td> <span title="attr-contenteditable">HTML elements</span>
<td> Whether the element is <span>editable</span>
<td> "<code title="">true</code>"; "<code title="">false</code>"
<tr>
<th> <code title="">contextmenu</code>
<td> <span title="attr-contextmenu">HTML elements</span>
<td> The element's context menu
<td> ID*
<tr>
<th> <code title="">controls</code>
<td> <code title="attr-media-controls">audio</code>;
<code title="attr-media-controls">video</code>
<td> Show user agent controls
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">coords</code>
<td> <code title="attr-area-coords">area</code>
<td> Coordinates for the shape to be created in an <span>image map</span>
<td> <span>Valid list of integers</span>*
<tr>
<th> <code title="">data</code>
<td> <code title="attr-object-data">object</code>
<td> Address of the resource
<td> <span>Valid URL</span>
<tr>
<th> <code title="">datetime</code>
<td> <code title="attr-mod-datetime">del</code>;
<code title="attr-mod-datetime">ins</code>
<td> Time and date of the change
<td> <span>Valid global date and time string</span>
<tr>
<th> <code title="">datetime</code>
<td> <code title="attr-time-datetime">time</code>
<td> Value of the element
<td> <span>Valid date or time string</span>*
<tr>
<th> <code title="">defer</code>
<td> <code title="attr-script-defer">script</code>
<td> Defer script execution
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">dir</code>
<td> <span title="attr-dir">HTML elements</span>
<td> <span title="the directionality">The text directionality</span> of the element
<td> "<code title="">ltr</code>"; "<code title="">rtl</code>"
<tr>
<th> <code title="">disabled</code>
<td> <code title="attr-fe-disabled">button</code>;
<code title="attr-command-disabled">command</code>;
<code title="attr-fieldset-disabled">fieldset</code>;
<code title="attr-fe-disabled">input</code>;
<code title="attr-fe-disabled">keygen</code>;
<code title="attr-optgroup-disabled">optgroup</code>;
<code title="attr-option-disabled">option</code>;
<code title="attr-fe-disabled">select</code>;
<code title="attr-fe-disabled">textarea</code>
<td> Whether the form control is disabled
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">draggable</code>
<td> <span title="attr-draggable">HTML elements</span>
<td> Whether the element is draggable
<td> "<code title="">true</code>"; "<code title="">false</code>"
<tr>
<th> <code title="">enctype</code>
<td> <code title="attr-fs-enctype">form</code>
<td> Form data set encoding type to use for <span>form submission</span>
<td> "<code title="attr-fs-enctype-urlencoded">application/x-www-form-urlencoded</code>"; "<code title="attr-fs-enctype-formdata">multipart/form-data</code>"; "<code title="attr-fs-enctype-text">text/plain</code>"
<tr>
<th> <code title="">for</code>
<td> <code title="attr-label-for">label</code>
<td> Associate the label with form control
<td> ID*
<tr>
<th> <code title="">for</code>
<td> <code title="attr-output-for">output</code>
<td> Specifies controls from which the output was calculated
<td> <span>Unordered set of unique space-separated tokens</span> consisting of IDs*
<tr>
<th> <code title="">form</code>
<td> <code title="attr-fae-form">button</code>;
<code title="attr-fae-form">fieldset</code>;
<code title="attr-fae-form">input</code>;
<code title="attr-fae-form">keygen</code>;
<code title="attr-fae-form">label</code>;
<code title="attr-fae-form">object</code>;
<code title="attr-fae-form">output</code>;
<code title="attr-fae-form">select</code>;
<code title="attr-fae-form">textarea</code>
<td> Associates the control with a <code>form</code> element
<td> ID*
<tr>
<th> <code title="">formaction</code>
<td> <code title="attr-fs-formaction">button</code>;
<code title="attr-fs-formaction">input</code>
<td> <span>URL</span> to use for <span>form submission</span>
<td> <span>Valid URL</span>
<tr>
<th> <code title="">formenctype</code>
<td> <code title="attr-fs-formenctype">button</code>;
<code title="attr-fs-formenctype">input</code>
<td> Form data set encoding type to use for <span>form submission</span>
<td> "<code title="attr-fs-enctype-urlencoded">application/x-www-form-urlencoded</code>"; "<code title="attr-fs-enctype-formdata">multipart/form-data</code>"; "<code title="attr-fs-enctype-text">text/plain</code>"
<tr>
<th> <code title="">formmethod</code>
<td> <code title="attr-fs-formmethod">button</code>;
<code title="attr-fs-formmethod">input</code>
<td> HTTP method to use for <span>form submission</span>
<td> "<code title="">GET</code>"; "<code title="">POST</code>"; "<code title="">PUT</code>"; "<code title="">DELETE</code>"
<tr>
<th> <code title="">formnovalidate</code>
<td> <code title="attr-fs-formnovalidate">button</code>;
<code title="attr-fs-formnovalidate">input</code>
<td> Bypass form control validation for <span>form submission</span>
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">formtarget</code>
<td> <code title="attr-fs-formtarget">button</code>;
<code title="attr-fs-formtarget">input</code>
<td> <span>Browsing context</span> for <span>form submission</span>
<td> <span>Valid browsing context name or keyword</span>
<tr>
<th> <code title="">headers</code>
<td> <code title="attr-tdth-headers">td</code>;
<code title="attr-tdth-headers">th</code>
<td> The header cells for this cell
<td> <span>Unordered set of unique space-separated tokens</span> consisting of IDs*
<tr>
<th> <code title="">height</code>
<td> <code title="attr-canvas-height">canvas</code>;
<code title="attr-dim-height">embed</code>;
<code title="attr-dim-height">iframe</code>;
<code title="attr-dim-height">img</code>;
<code title="attr-dim-height">input</code>;
<code title="attr-dim-height">object</code>;
<code title="attr-dim-height">video</code>
<td> Vertical dimension
<td> <span>Valid non-negative integer</span>
<tr>
<th> <code title="">hidden</code>
<td> <span title="attr-hidden">HTML elements</span>
<td> Whether the element is relevant
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">high</code>
<td> <code title="attr-meter-high">meter</code>
<td> Low limit of high range
<td> <span>Valid floating point number</span>*
<tr>
<th> <code title="">href</code>
<td> <code title="attr-hyperlink-href">a</code>;
<code title="attr-hyperlink-href">area</code>;
<code title="attr-link-href">link</code>
<td> Address of the <span>hyperlink</span>
<td> <span>Valid URL</span>
<tr>
<th> <code title="">href</code>
<td> <code title="attr-base-href">base</code>
<td> <span>Document base URL</span>
<td> <span>Valid URL</span>
<tr>
<th> <code title="">hreflang</code>
<td> <code title="attr-hyperlink-hreflang">a</code>;
<code title="attr-hyperlink-hreflang">area</code>;
<code title="attr-link-hreflang">link</code>
<td> Language of the linked resource
<td> Valid BCP 47 language code
<tr>
<th> <code title="">http-equiv</code>
<td> <code title="attr-meta-http-equiv">meta</code>
<td> Pragma directive
<td> Text*
<tr>
<th> <code title="">icon</code>
<td> <code title="attr-command-icon">command</code>
<td> Icon for the command
<td> <span>Valid URL</span>
<tr>
<th> <code title="">id</code>
<td> <span title="attr-id">HTML elements</span>
<td> The element's <span title="concept-id">ID</span>
<td> Text*
<tr>
<th> <code title="">ismap</code>
<td> <code title="attr-img-ismap">img</code>
<td> Whether the image is a server-side image map
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">itemid</code>
<td> <span title="attr-itemid">HTML elements</span>
<td> <span>Global identifier</span> for a microdata item
<td> <span title="valid URL">Valid URL</span>
<tr>
<th> <code title="">itemprop</code>
<td> <span title="attr-itemprop">HTML elements</span>
<td> <span>Property names</span> of a microdata item
<td> <span>Unordered set of unique space-separated tokens</span> consisting of <span title="absolute URL">valid absolute URLs</span>, <span title="defined property name">defined property names</span>, or text*
<tr>
<th> <code title="">itemref</code>
<td> <code title="attr-itemref">itemref</code>
<td> Referenced elements
<td> <span>Unordered set of unique space-separated tokens</span> consisting of IDs*
<tr>
<th> <code title="">itemscope</code>
<td> <span title="attr-itemscope">HTML elements</span>
<td> Introduces a microdata item
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">itemtype</code>
<td> <span title="attr-itemtype">HTML elements</span>
<td> <span>Item type</span> of a microdata item
<td> <span title="absolute url">Valid absolute URL</span>*
<tr>
<th> <code title="">keytype</code>
<td> <code title="attr-keygen-keytype">keygen</code>
<td> The type of cryptographic key to generate
<td> Text*
<tr>
<th> <code title="">label</code>
<td> <code title="attr-command-label">command</code>;
<code title="attr-menu-label">menu</code>;
<code title="attr-optgroup-label">optgroup</code>;
<code title="attr-option-label">option</code>
<td> User-visible label
<td> Text
<tr>
<th> <code title="">lang</code>
<td> <span title="attr-lang">HTML elements</span>
<td> <span>Language</span> of the element
<td> Valid BCP 47 language code or the empty string
<tr>
<th> <code title="">list</code>
<td> <code title="attr-input-list">input</code>
<td> List of autocomplete options
<td> ID*
<tr>
<th> <code title="">loop</code>
<td> <code title="attr-media-loop">audio</code>;
<code title="attr-media-loop">video</code>
<td> Whether to loop the <span>media resource</span>
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">low</code>
<td> <code title="attr-meter-low">meter</code>
<td> High limit of low range
<td> <span>Valid floating point number</span>*
<tr>
<th> <code title="">manifest</code>
<td> <code title="attr-html-manifest">html</code>
<td> <span title="concept-appcache-manifest">Application cache manifest</span>
<td> <span>Valid URL</span>
<tr>
<th> <code title="">max</code>
<td> <code title="attr-input-max">input</code>
<td> Maximum value
<td> varies*
<tr>
<th> <code title="">max</code>
<td> <code title="attr-meter-max">meter</code>;
<code title="attr-progress-max">progress</code>
<td> Upper bound of range
<td> <span>Valid floating point number</span>*
<tr>
<th> <code title="">maxlength</code>
<td> <code title="attr-input-maxlength">input</code>;
<code title="attr-textarea-maxlength">textarea</code>
<td> Maximum length of value
<td> <span>Valid non-negative integer</span>
<tr>
<th> <code title="">media</code>
<td> <code title="attr-hyperlink-media">a</code>;
<code title="attr-hyperlink-media">area</code>;
<code title="attr-link-media">link</code>;
<code title="attr-source-media">source</code>;
<code title="attr-style-media">style</code>
<td> Applicable media
<td> <span>Valid media query</span>
<tr>
<th> <code title="">method</code>
<td> <code title="attr-fs-method">form</code>
<td> HTTP method to use for <span>form submission</span>
<td> "<code title="">GET</code>"; "<code title="">POST</code>"; "<code title="">PUT</code>"; "<code title="">DELETE</code>"
<tr>
<th> <code title="">min</code>
<td> <code title="attr-input-min">input</code>
<td> Minimum value
<td> varies*
<tr>
<th> <code title="">min</code>
<td> <code title="attr-meter-min">meter</code>
<td> Lower bound of range
<td> <span>Valid floating point number</span>*
<tr>
<th> <code title="">multiple</code>
<td> <code title="attr-input-multiple">input</code>;
<code title="attr-select-multiple">select</code>
<td> Whether to allow multiple values
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">name</code>
<td> <code title="attr-fe-name">button</code>;
<code title="attr-fe-name">fieldset</code>;
<code title="attr-fe-name">input</code>;
<code title="attr-fe-name">keygen</code>;
<code title="attr-fe-name">output</code>;
<code title="attr-fe-name">select</code>;
<code title="attr-fe-name">textarea</code>
<td> Name of form control to use for <span>form submission</span> and in the <code title="dom-form-elements">form.elements</code> API
<td> Text*
<tr>
<th> <code title="">name</code>
<td> <code title="attr-form-name">form</code>
<td> Name of form to use in the <code title="dom-document-forms">document.forms</code> API
<td> Text*
<tr>
<th> <code title="">name</code>
<td> <code title="attr-iframe-name">iframe</code>;
<code title="attr-object-name">object</code>
<td> Name of <span>nested browsing context</span>
<td> <span>Valid browsing context name or keyword</span>
<tr>
<th> <code title="">name</code>
<td> <code title="attr-map-name">map</code>
<td> Name of <span>image map</span> to reference from the <code title="attr-hyperlink-usemap">usemap</code> attribute
<td> Text*
<tr>
<th> <code title="">name</code>
<td> <code title="attr-meta-name">meta</code>
<td> Metadata name
<td> Text*
<tr>
<th> <code title="">name</code>
<td> <code title="attr-param-name">param</code>
<td> Name of parameter
<td> Text
<tr>
<th> <code title="">novalidate</code>
<td> <code title="attr-fs-novalidate">form</code>
<td> Bypass form control validation for <span>form submission</span>
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">open</code>
<td> <code title="attr-details-open">details</code>
<td> Whether the details are visible
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">optimum</code>
<td> <code title="attr-meter-optimum">meter</code>
<td> Optimum value in gauge
<td> <span>Valid floating point number</span>*
<tr>
<th> <code title="">pattern</code>
<td> <code title="attr-input-pattern">input</code>
<td> Pattern to be matched by the form control's value
<td> Regular expression matching the JavaScript <i title="">Pattern</i> production
<tr>
<th> <code title="">ping</code>
<td> <code title="attr-hyperlink-ping">a</code>;
<code title="attr-hyperlink-ping">area</code>
<td> <span title="URL">URLs</span> to ping
<td> <span>Set of space-separated tokens</span> consisting of <span title="valid URL">valid URLs</span>
<tr>
<th> <code title="">placeholder</code>
<td> <code title="attr-input-placeholder">input</code>;
<code title="attr-textarea-placeholder">textarea</code>
<td> User-visible label to be placed within the form control
<td> Text*
<tr>
<th> <code title="">poster</code>
<td> <code title="attr-video-poster">video</code>
<td> Poster frame to show prior to video playback
<td> <span>Valid URL</span>
<tr>
<th> <code title="">pubdate</code>
<td> <code title="attr-time-pubdate">time</code>
<td> Whether the element's value represents a publication time for the nearest <code>article</code> or <code>body</code>
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">radiogroup</code>
<td> <code title="attr-command-radiogroup">command</code>
<td> Name of group of commands to treat as a radio button group
<td> Text
<tr>
<th> <code title="">readonly</code>
<td> <code title="attr-input-readonly">input</code>;
<code title="attr-textarea-readonly">textarea</code>
<td> Whether to allow the value to be edited by the user
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">rel</code>
<td> <code title="attr-hyperlink-rel">a</code>;
<code title="attr-hyperlink-rel">area</code>;
<code title="attr-link-rel">link</code>
<td> Relationship between the document containing the hyperlink and the destination resource
<td> <span>Set of space-separated tokens</span>*
<tr>
<th> <code title="">required</code>
<td> <code title="attr-input-required">input</code>;
<code title="attr-textarea-required">textarea</code>
<td> Whether the control is required for <span>form submission</span>
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">reversed</code>
<td> <code title="attr-ol-reversed">ol</code>
<td> Number the list backwards
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">rows</code>
<td> <code title="attr-textarea-rows">textarea</code>
<td> Number of lines to show
<td> <span>Valid non-negative integer</span> greater than zero
<tr>
<th> <code title="">rowspan</code>
<td> <code title="attr-tdth-rowspan">td</code>;
<code title="attr-tdth-rowspan">th</code>
<td> Number of rows that the cell is to span
<td> <span>Valid non-negative integer</span>
<tr>
<th> <code title="">sandbox</code>
<td> <code title="attr-iframe-sandbox">iframe</code>
<td> Security rules for nested content
<td> <span>Unordered set of unique space-separated tokens</span> consisting of
"<code title="attr-iframe-sandbox-allow-same-origin">allow-same-origin</code>",
"<code title="attr-iframe-sandbox-allow-forms">allow-forms</code>", and
"<code title="attr-iframe-sandbox-allow-scripts">allow-scripts</code>"
<tr>
<th> <code title="">spellcheck</code>
<td> <span title="attr-spellcheck">HTML elements</span>
<td> Whether the element is to have its spelling and grammar checked
<td> "<code title="">true</code>"; "<code title="">false</code>"
<tr>
<th> <code title="">scope</code>
<td> <code title="attr-th-scope">th</code>
<td> Specifies which cells the header cell applies to
<td> "<code title="attr-th-scope-row">row</code>";
"<code title="attr-th-scope-col">col</code>";
"<code title="attr-th-scope-rowgroup">rowgroup</code>";
"<code title="attr-th-scope-colgroup">colgroup</code>"
<tr>
<th> <code title="">scoped</code>
<td> <code title="attr-style-scoped">style</code>
<td> Whether the styles apply to the entire document or just the parent subtree
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">seamless</code>
<td> <code title="attr-iframe-seamless">iframe</code>
<td> Whether to apply the document's styles to the nested content
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">selected</code>
<td> <code title="attr-option-selected">option</code>
<td> Whether the option is selected by default
<td> <span>Boolean attribute</span>
<tr>
<th> <code title="">shape</code>
<td> <code title="attr-area-shape">area</code>
<td> The kind of shape to be created in an <span>image map</span>
<td> "<code title="attr-area-shape-keyword-circle">circle</code>";
"<code title="attr-area-shape-keyword-default">default</code>";
"<code title="attr-area-shape-keyword-poly">poly</code>";
"<code title="attr-area-shape-keyword-rect">rect</code>"
<tr>
<th> <code title="">size</code>
<td> <code title="attr-input-size">input</code>;
<code title="attr-select-size">select</code>
<td> Size of the control
<td> <span>Valid non-negative integer</span> greater than zero
<tr>
<th> <code title="">sizes</code>
<td> <code title="attr-link-sizes">link</code>
<td> Sizes of the icons (for <code title="attr-link-rel">rel</code>="<code title="rel-icon">icon</code>")
<td> List of sizes*
<tr>
<th> <code title="">span</code>
<td> <code title="attr-col-span">col</code>;
<code title="attr-colgroup-span">colgroup</code>
<td> Number of columns spanned by the element
<td> <span>Valid non-negative integer</span> greater than zero
<tr>
<th> <code title="">src</code>
<td> <code title="attr-media-src">audio</code>;
<code title="attr-embed-src">embed</code>;
<code title="attr-iframe-src">iframe</code>;
<code title="attr-img-src">img</code>;
<code title="attr-input-src">input</code>;
<code title="attr-script-src">script</code>;
<code title="attr-source-src">source</code>;
<code title="attr-media-src">video</code>
<td> Address of the resource
<td> <span>Valid URL</span>
<tr>
<th> <code title="">start</code>
<td> <code title="attr-ol-start">ol</code>
<td> Ordinal value of the first item
<td> <span>Valid integer</span>
<tr>
<th> <code title="">step</code>
<td> <code title="attr-input-step">input</code>
<td> Granularity to be matched by the form control's value
<td> <span>Valid floating point number</span> greater than zero, or "<code title="">any</code>"
<tr>
<th> <code title="">style</code>
<td> <span title="attr-style">HTML elements</span>
<td> Presentational and formatting instructions
<td> CSS declarations*
<tr>
<th> <code title="">summary</code>
<td> <code title="attr-table-summary">table</code>
<td> Explanatory text for complex tables for users of screen readers
<td> Text*
<tr>
<th> <code title="">tabindex</code>
<td> <span title="attr-tabindex">HTML elements</span>
<td> Whether the element is focusable, and the relative order of the element for the purposes of sequential focus navigation
<td> <span>Valid integer</span>
<tr>
<th> <code title="">target</code>
<td> <code title="attr-hyperlink-target">a</code>;
<code title="attr-hyperlink-target">area</code>
<td> <span>Browsing context</span> for <span>hyperlink</span> <span title="navigate">navigation</span>
<td> <span>Valid browsing context name or keyword</span>
<tr>
<th> <code title="">target</code>
<td> <code title="attr-base-target">base</code>
<td> Default <span>browsing context</span> for <span>hyperlink</span> <span title="navigate">navigation</span> and <span>form submission</span>
<td> <span>Valid browsing context name or keyword</span>
<tr>
<th> <code title="">target</code>
<td> <code title="attr-fs-target">form</code>
<td> <span>Browsing context</span> for <span>form submission</span>
<td> <span>Valid browsing context name or keyword</span>
<tr>
<th> <code title="">title</code>
<td> <span title="attr-title">HTML elements</span>
<td> Advisory information for the element
<td> Text
<tr>
<th> <code title="">title</code>
<td> <code title="attr-abbr-title">abbr</code>;
<code title="attr-dfn-title">dfn</code>
<td> Full term or expansion of abbreviation
<td> Text
<tr>
<th> <code title="">title</code>
<td> <code title="attr-command-title">command</code>
<td> Hint describing the command
<td> Text
<tr>
<th> <code title="">title</code>
<td> <code title="attr-link-title">link</code>
<td> Title of the link
<td> Text
<tr>
<th> <code title="">title</code>
<td> <code title="attr-link-title">link</code>;
<code title="attr-style-title">style</code>
<td> Alternative style sheet set name
<td> Text
<tr>
<th> <code title="">type</code>
<td> <code title="attr-hyperlink-type">a</code>;
<code title="attr-hyperlink-type">area</code>;
<code title="attr-link-type">link</code>
<td> Hint for the type of the referenced resource
<td> <span>Valid MIME type</span>
<tr>
<th> <code title="">type</code>
<td> <code title="attr-button-type">button</code>
<td> Type of button
<td> "<code title="attr-button-type-submit">submit</code>";
"<code title="attr-button-type-reset">reset</code>";
"<code title="attr-button-type-button">button</code>"
<tr>
<th> <code title="">type</code>
<td> <code title="attr-button-type">button</code>;
<code title="attr-input-type">input</code>
<td> Type of form control
<td> <span title="attr-input-type"><code>input</code> type keyword</span>
<tr>
<th> <code title="">type</code>
<td> <code title="attr-command-type">command</code>
<td> Type of command
<td> "<code title="attr-command-type-keyword-command">command</code>";
"<code title="attr-command-type-keyword-checkbox">checkbox</code>";
"<code title="attr-command-type-keyword-radio">radio</code>"
<tr>
<th> <code title="">type</code>
<td> <code title="attr-embed-type">embed</code>;
<code title="attr-object-type">object</code>;
<code title="attr-script-type">script</code>;
<code title="attr-source-type">source</code>;
<code title="attr-style-type">style</code>
<td> Type of embedded resource
<td> <span>Valid MIME type</span>
<tr>
<th> <code title="">type</code>
<td> <code title="attr-menu-type">menu</code>
<td> Type of menu
<td> "<code title="context menu state">context</code>"; "<code title="toolbar state">toolbar</code>"
<tr>
<th> <code title="">usemap</code>
<td> <code title="attr-hyperlink-usemap">img</code>;
<code title="attr-hyperlink-usemap">object</code>
<td> Name of <span>image map</span> to use
<td> <span>Valid hash-name reference</span>*
<tr>
<th> <code title="">value</code>
<td> <code title="attr-button-value">button</code>;
<code title="attr-option-value">option</code>
<td> Value to be used for <span>form submission</span>
<td> Text
<tr>
<th> <code title="">value</code>
<td> <code title="attr-input-value">input</code>
<td> Value of the form control
<td> varies*
<tr>
<th> <code title="">value</code>
<td> <code title="attr-li-value">li</code>
<td> Ordinal value of the list item
<td> <span>Valid integer</span>
<tr>
<th> <code title="">value</code>
<td> <code title="attr-meter-value">meter</code>;
<code title="attr-progress-value">progress</code>
<td> Current value of the element
<td> <span>Valid floating point number</span>
<tr>
<th> <code title="">value</code>
<td> <code title="attr-param-value">param</code>
<td> Value of parameter
<td> Text
<tr>
<th> <code title="">width</code>
<td> <code title="attr-canvas-width">canvas</code>;
<code title="attr-dim-width">embed</code>;
<code title="attr-dim-width">iframe</code>;
<code title="attr-dim-width">img</code>;
<code title="attr-dim-width">input</code>;
<code title="attr-dim-width">object</code>;
<code title="attr-dim-width">video</code>
<td> Horizontal dimension
<td> <span>Valid non-negative integer</span>
<tr>
<th> <code title="">wrap</code>
<td> <code title="attr-textarea-wrap">textarea</code>
<td> How the value of the form control is to be wrapped for <span>form submission</span>
<td> "<code title="attr-textarea-wrap-soft">soft</code>";
"<code title="attr-textarea-wrap-hard">hard</code>"
</table>
<p>An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.</p>
<hr>
<table>
<caption>List of event handler content attributes</caption>
<thead>
<tr>
<th> Attribute
<th> Element(s)
<th> Description
<th> Value
<tbody>
<tr>
<th> <code title="">onabort</code>
<td> <span title="handler-onabort">HTML elements</span>
<td> <code title="event-abort">abort</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onafterprint</code>
<td> <code title="handler-window-onafterprint">body</code>
<td> <code title="event-afterprint">afterprint</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onbeforeprint</code>
<td> <code title="handler-window-onbeforeprint">body</code>
<td> <code title="event-beforeprint">beforeprint</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onbeforeunload</code>
<td> <code title="handler-window-onbeforeunload">body</code>
<td> <code title="event-beforeunload">beforeunload</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onblur</code>
<td> <code title="handler-window-onblur">body</code>
<td> <code title="event-blur">blur</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onblur</code>
<td> <span title="handler-onblur">HTML elements</span>
<td> <code title="event-blur">blur</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">oncanplay</code>
<td> <span title="handler-oncanplay">HTML elements</span>
<td> <code title="event-media-canplay">canplay</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">oncanplaythrough</code>
<td> <span title="handler-oncanplaythrough">HTML elements</span>
<td> <code title="event-media-canplaythrough">canplaythrough</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onchange</code>
<td> <span title="handler-onchange">HTML elements</span>
<td> <code title="event-change">change</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onclick</code>
<td> <span title="handler-onclick">HTML elements</span>
<td> <code title="event-click">click</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">oncontextmenu</code>
<td> <span title="handler-oncontextmenu">HTML elements</span>
<td> <code title="event-contextmenu">contextmenu</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondblclick</code>
<td> <span title="handler-ondblclick">HTML elements</span>
<td> <code title="event-dblclick">dblclick</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondrag</code>
<td> <span title="handler-ondrag">HTML elements</span>
<td> <code title="event-drag">drag</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondragend</code>
<td> <span title="handler-ondragend">HTML elements</span>
<td> <code title="event-dragend">dragend</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondragenter</code>
<td> <span title="handler-ondragenter">HTML elements</span>
<td> <code title="event-dragenter">dragenter</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondragleave</code>
<td> <span title="handler-ondragleave">HTML elements</span>
<td> <code title="event-dragleave">dragleave</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondragover</code>
<td> <span title="handler-ondragover">HTML elements</span>
<td> <code title="event-dragover">dragover</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondragstart</code>
<td> <span title="handler-ondragstart">HTML elements</span>
<td> <code title="event-dragstart">dragstart</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondrop</code>
<td> <span title="handler-ondrop">HTML elements</span>
<td> <code title="event-drop">drop</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ondurationchange</code>
<td> <span title="handler-ondurationchange">HTML elements</span>
<td> <code title="event-media-durationchange">durationchange</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onemptied</code>
<td> <span title="handler-onemptied">HTML elements</span>
<td> <code title="event-media-emptied">emptied</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onended</code>
<td> <span title="handler-onended">HTML elements</span>
<td> <code title="event-media-ended">ended</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onerror</code>
<td> <code title="handler-window-onerror">body</code>
<td> <code title="event-error">error</code> event handler for <code>Window</code> object, and handler for <a href="#runtime-script-errors">script error notifications</a>
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onerror</code>
<td> <span title="handler-onerror">HTML elements</span>
<td> <code title="event-error">error</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onfocus</code>
<td> <code title="handler-window-onfocus">body</code>
<td> <code title="event-focus">focus</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onfocus</code>
<td> <span title="handler-onfocus">HTML elements</span>
<td> <code title="event-focus">focus</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onformchange</code>
<td> <span title="handler-onformchange">HTML elements</span>
<td> <code title="event-formchange">formchange</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onforminput</code>
<td> <span title="handler-onforminput">HTML elements</span>
<td> <code title="event-forminput">forminput</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onhashchange</code>
<td> <code title="handler-window-onhashchange">body</code>
<td> <code title="event-hashchange">hashchange</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">oninput</code>
<td> <span title="handler-oninput">HTML elements</span>
<td> <code title="event-input">input</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">oninvalid</code>
<td> <span title="handler-oninvalid">HTML elements</span>
<td> <code title="event-invalid">invalid</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onkeydown</code>
<td> <span title="handler-onkeydown">HTML elements</span>
<td> <code title="event-keydown">keydown</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onkeypress</code>
<td> <span title="handler-onkeypress">HTML elements</span>
<td> <code title="event-keypress">keypress</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onkeyup</code>
<td> <span title="handler-onkeyup">HTML elements</span>
<td> <code title="event-keyup">keyup</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onload</code>
<td> <code title="handler-window-onload">body</code>
<td> <code title="event-load">load</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onload</code>
<td> <span title="handler-onload">HTML elements</span>
<td> <code title="event-load">load</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onloadeddata</code>
<td> <span title="handler-onloadeddata">HTML elements</span>
<td> <code title="event-media-loadeddata">loadeddata</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onloadedmetadata</code>
<td> <span title="handler-onloadedmetadata">HTML elements</span>
<td> <code title="event-media-loadedmetadata">loadedmetadata</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onloadstart</code>
<td> <span title="handler-onloadstart">HTML elements</span>
<td> <code title="event-media-loadstart">loadstart</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onmessage</code>
<td> <code title="handler-window-onmessage">body</code>
<td> <code title="event-message">message</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onmousedown</code>
<td> <span title="handler-onmousedown">HTML elements</span>
<td> <code title="event-mousedown">mousedown</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onmousemove</code>
<td> <span title="handler-onmousemove">HTML elements</span>
<td> <code title="event-mousemove">mousemove</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onmouseout</code>
<td> <span title="handler-onmouseout">HTML elements</span>
<td> <code title="event-mouseout">mouseout</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onmouseover</code>
<td> <span title="handler-onmouseover">HTML elements</span>
<td> <code title="event-mouseover">mouseover</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onmouseup</code>
<td> <span title="handler-onmouseup">HTML elements</span>
<td> <code title="event-mouseup">mouseup</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onmousewheel</code>
<td> <span title="handler-onmousewheel">HTML elements</span>
<td> <code title="event-mousewheel">mousewheel</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onoffline</code>
<td> <code title="handler-window-onoffline">body</code>
<td> <code title="event-offline">offline</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ononline</code>
<td> <code title="handler-window-ononline">body</code>
<td> <code title="event-online">online</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onpause</code>
<td> <span title="handler-onpause">HTML elements</span>
<td> <code title="event-media-pause">pause</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onplay</code>
<td> <span title="handler-onplay">HTML elements</span>
<td> <code title="event-media-play">play</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onplaying</code>
<td> <span title="handler-onplaying">HTML elements</span>
<td> <code title="event-media-playing">playing</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onpagehide</code>
<td> <code title="handler-window-onpagehide">body</code>
<td> <code title="event-pagehide">pagehide</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onpageshow</code>
<td> <code title="handler-window-onpageshow">body</code>
<td> <code title="event-pageshow">pageshow</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onpopstate</code>
<td> <code title="handler-window-onpopstate">body</code>
<td> <code title="event-popstate">popstate</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onprogress</code>
<td> <span title="handler-onprogress">HTML elements</span>
<td> <code title="event-media-progress">progress</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onratechange</code>
<td> <span title="handler-onratechange">HTML elements</span>
<td> <code title="event-media-ratechange">ratechange</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onreadystatechange</code>
<td> <span title="handler-onreadystatechange">HTML elements</span>
<td> <code title="event-readystatechange">readystatechange</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onredo</code>
<td> <code title="handler-window-onredo">body</code>
<td> <code title="event-redo">redo</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onresize</code>
<td> <code title="handler-window-onresize">body</code>
<td> <code title="event-resize">resize</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onscroll</code>
<td> <span title="handler-onscroll">HTML elements</span>
<td> <code title="event-scroll">scroll</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onseeked</code>
<td> <span title="handler-onseeked">HTML elements</span>
<td> <code title="event-media-seeked">seeked</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onseeking</code>
<td> <span title="handler-onseeking">HTML elements</span>
<td> <code title="event-media-seeking">seeking</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onselect</code>
<td> <span title="handler-onselect">HTML elements</span>
<td> <code title="event-select">select</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onshow</code>
<td> <span title="handler-onshow">HTML elements</span>
<td> <code title="event-show">show</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onstalled</code>
<td> <span title="handler-onstalled">HTML elements</span>
<td> <code title="event-media-stalled">stalled</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onstorage</code>
<td> <code title="handler-window-onstorage">body</code>
<td> <code title="event-storage">storage</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onsubmit</code>
<td> <span title="handler-onsubmit">HTML elements</span>
<td> <code title="event-submit">submit</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onsuspend</code>
<td> <span title="handler-onsuspend">HTML elements</span>
<td> <code title="event-media-suspend">suspend</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">ontimeupdate</code>
<td> <span title="handler-ontimeupdate">HTML elements</span>
<td> <code title="event-media-timeupdate">timeupdate</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onundo</code>
<td> <code title="handler-window-onundo">body</code>
<td> <code title="event-undo">undo</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onunload</code>
<td> <code title="handler-window-onunload">body</code>
<td> <code title="event-unload">unload</code> event handler for <code>Window</code> object
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onvolumechange</code>
<td> <span title="handler-onvolumechange">HTML elements</span>
<td> <code title="event-media-volumechange">volumechange</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
<tr>
<th> <code title="">onwaiting</code>
<td> <span title="handler-onwaiting">HTML elements</span>
<td> <code title="event-media-waiting">waiting</code> event handler
<td> <span title="event handler content attributes">Event handler content attribute</span>
</table>
<!-- v2 for completeness: (also search for REFLECTIDL)
<h3 class="no-num">Reflecting IDL attributes</h3>
<p><i>This section is non-normative.</i></p>
<table>
<caption>List of <dfn>reflecting IDL attributes</dfn></caption>
<thead>
<tr>
<th> Interface
<th> Element(s)
<th> IDL attribute
<th> Reflects...
<tbody>
...
<tr>
<td> <code>HTMLElement</code>
<td> <span>HTML elements</span>
<td> <code title="dom-contextMenu">contextMenu</code>
<td> <code title="attr-contextmenu">contextmenu</code>
<tr>
<td> <code>HTMLOptionElement</code>
<td> <code>option</code>
<td> <code title="dom-option-text">text</code>
<td> <code>textContent</code>
</table>
( include option.text; textarea.defaultValue, and other attributes that "reflect" the element's textContent )
-->
<h3 class="no-num">Interfaces</h3>
<p><i>This section is non-normative.</i></p>
<table>
<caption>List of interfaces for elements</caption>
<thead>
<tr>
<th> Element(s)
<th> Interface(s)
<tbody>
<tr>
<td> <code>a</code>
<td> <code>HTMLAnchorElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>abbr</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>address</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>area</code>
<td> <code>HTMLAreaElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>article</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>aside</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>audio</code>
<td> <code>HTMLAudioElement</code> : <code>HTMLMediaElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>b</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>base</code>
<td> <code>HTMLBaseElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>bdo</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>blockquote</code>
<td> <code>HTMLQuoteElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>body</code>
<td> <code>HTMLBodyElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>br</code>
<td> <code>HTMLBRElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>button</code>
<td> <code>HTMLButtonElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>canvas</code>
<td> <code>HTMLCanvasElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>caption</code>
<td> <code>HTMLTableCaptionElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>cite</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>code</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>col</code>
<td> <code>HTMLTableSectionElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>colgroup</code>
<td> <code>HTMLTableColElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>datalist</code>
<td> <code>HTMLDataListElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>dd</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>details</code>
<td> <code>HTMLDetailsElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>div</code>
<td> <code>HTMLDivElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>dl</code>
<td> <code>HTMLDListElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>dt</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>em</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>embed</code>
<td> <code>HTMLEmbedElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>fieldset</code>
<td> <code>HTMLFieldSetElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>figure</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>footer</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>form</code>
<td> <code>HTMLFormElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>head</code>
<td> <code>HTMLHeadElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>h1</code>
<td> <code>HTMLHeadingElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>h2</code>
<td> <code>HTMLHeadingElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>h3</code>
<td> <code>HTMLHeadingElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>h4</code>
<td> <code>HTMLHeadingElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>h5</code>
<td> <code>HTMLHeadingElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>h6</code>
<td> <code>HTMLHeadingElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>header</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>hgroup</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>hr</code>
<td> <code>HTMLHRElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>html</code>
<td> <code>HTMLHtmlElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>i</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>iframe</code>
<td> <code>HTMLIFrameElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>img</code>
<td> <code>HTMLImageElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>input</code>
<td> <code>HTMLInputElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>ins</code>
<td> <code>HTMLModElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>kbd</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>keygen</code>
<td> <code>HTMLKeygenElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>label</code>
<td> <code>HTMLLabelElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>legend</code>
<td> <code>HTMLLegendElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>li</code>
<td> <code>HTMLLIElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>link</code>
<td> <code>HTMLLinkElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>map</code>
<td> <code>HTMLMapElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>mark</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>meter</code>
<td> <code>HTMLMeterElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>nav</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>noscript</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>object</code>
<td> <code>HTMLObjectElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>ol</code>
<td> <code>HTMLOListElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>optgroup</code>
<td> <code>HTMLOptGroupElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>option</code>
<td> <code>HTMLOptionElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>output</code>
<td> <code>HTMLOutputElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>p</code>
<td> <code>HTMLParagraphElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>param</code>
<td> <code>HTMLParamElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>pre</code>
<td> <code>HTMLPreElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>progress</code>
<td> <code>HTMLProgressElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>q</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>rp</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>rt</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>ruby</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>samp</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>section</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>select</code>
<td> <code>HTMLSelectElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>small</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>source</code>
<td> <code>HTMLSourceElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>span</code>
<td> <code>HTMLSpanElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>strong</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>style</code>
<td> <code>HTMLStyleElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>sub</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>sup</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>table</code>
<td> <code>HTMLTableElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>td</code>
<td> <code>HTMLTableDataCellElement</code> : <code>HTMLTableCellElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>textarea</code>
<td> <code>HTMLTextAreaElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>th</code>
<td> <code>HTMLTableHeaderCellElement</code> : <code>HTMLTableCellElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>thead</code>
<td> <code>HTMLTableRowElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>time</code>
<td> <code>HTMLTimeElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>title</code>
<td> <code>HTMLTitleElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>ul</code>
<td> <code>HTMLUListElement</code> : <code>HTMLElement</code>
<tr>
<td> <code>var</code>
<td> <code>HTMLElement</code>
<tr>
<td> <code>video</code>
<td> <code>HTMLVideoElement</code> : <code>HTMLMediaElement</code> : <code>HTMLElement</code>
</table>
<!--END complete--><!-- (only has events from HTML5) -->
<h3 class="no-num">Events</h3>
<p><i>This section is non-normative.</i></p>
<table>
<caption>List of events</caption>
<thead>
<tr>
<th> Event
<th> Interface
<th> Description
<tbody>
<tr>
<td> <code title="event-DOMActivate">DOMActivate</code>
<td> <code>Event</code>
<td> Fired at an element before its <span>activation behavior</span> is run
<tr>
<td> <code title="event-DOMContentLoaded">DOMContentLoaded</code>
<td> <code>Event</code>
<td> Fired at the <code>Document</code> once it and its scripts have loaded, without waiting for other subresources
<tr>
<td> <code title="event-abort">abort</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> when the download was aborted by the user
<tr>
<td> <code title="event-afterprint">afterprint</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> after printing
<tr>
<td> <code title="event-beforeprint">beforeprint</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> before printing
<tr>
<td> <code title="event-beforeunload">beforeunload</code>
<td> <code>BeforeUnloadEvent</code>
<td> Fired at the <code>Window</code> when the page is about to be unloaded, in case the page would like to show a warning prompt
<tr>
<td> <code title="event-blur">blur</code>
<td> <code>Event</code>
<td> Fired at nodes losing focus
<tr>
<td> <code title="event-change">change</code>
<td> <code>Event</code>
<td> Fired at controls when the user commits a value change
<tr>
<td> <code title="event-contextmenu">contextmenu</code>
<td> <code>Event</code>
<td> Fired at elements when the user requests their context menu
<tr>
<td> <code title="event-error">error</code>
<td> <code>Event</code>
<td> Fired at elements when network and script errors occur
<tr>
<td> <code title="event-focus">focus</code>
<td> <code>Event</code>
<td> Fired at nodes gaining focus
<tr>
<td> <code title="event-formchange">formchange</code>
<td> <code>Event</code>
<td> Fired at form controls when the user commits a value change to a control on the form
<tr>
<td> <code title="event-forminput">forminput</code>
<td> <code>Event</code>
<td> Fired at form controls when the user changes the value of a control on the form
<tr>
<td> <code title="event-hashchange">hashchange</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> when the fragment identifier part of <span>the document's current address</span> changes
<tr>
<td> <code title="event-input">input</code>
<td> <code>Event</code>
<td> Fired at controls when the user changes the value
<tr>
<td> <code title="event-invalid">invalid</code>
<td> <code>Event</code>
<td> Fired at controls during form validation if they do not satisfy their constraints
<tr>
<td> <code title="event-load">load</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> when the document has finished loading; fired at an element containing a resource (e.g. <code>img</code>, <code>embed</code>) when its resource has finished loading
<tr>
<td> <code title="event-message">message</code>
<td> <code>MessageEvent</code>
<td> Fired at an object when the object receives a message
<tr>
<td> <code title="event-offline">offline</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> when the network connections fails
<tr>
<td> <code title="event-online">online</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> when the network connections returns
<tr>
<td> <code title="event-pagehide">pagehide</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> when the page's entry in the <span>session history</span> stops being the <span>current entry</span>
<tr>
<td> <code title="event-pageshow">pageshow</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> when the page's entry in the <span>session history</span> becomes the <span>current entry</span>
<tr>
<td> <code title="event-popstate">popstate</code>
<td> <code>PopStateEvent</code>
<td> Fired at the <code>Window</code> when the user navigates the <span>session history</span>
<tr>
<td> <code title="event-readystatechange">readystatechange</code>
<td> <code>Event</code>
<td> Fired at the <code>Document</code> when it finishes parsing and again when all its subresources have finished loading
<tr>
<td> <code title="event-redo">redo</code>
<td> <code>UndoManagerEvent</code>
<td> Fired at the <code>Window</code> object when the user <span title="do-redo">goes forward in the undo transaction history</span>
<tr>
<td> <code title="event-reset">reset</code>
<td> <code>Event</code>
<td> Fired at a <code>form</code> element when it is <span title="concept-form-reset">reset</span>
<tr>
<td> <code title="event-show">show</code>
<td> <code>Event</code>
<td> Fired at a <code>menu</code> element when it is shown as a context menu
<tr>
<td> <code title="event-submit">submit</code>
<td> <code>Event</code>
<td> Fired at a <code>form</code> element when it is <span title="concept-form-submit">submitted</span>
<tr>
<td> <code title="event-undo">undo</code>
<td> <code>UndoManagerEvent</code>
<td> Fired at the <code>Window</code> object when the user <span title="do-undo">goes backward in the undo transaction history</span>
<tr>
<td> <code title="event-unload">unload</code>
<td> <code>Event</code>
<td> Fired at the <code>Window</code> object when the page is going away
</table>
<p class="note">See also <a href="#mediaevents">media element
events</a>, <a href="#appcacheevents">application cache events</a>,
and <a href="#dndevents">drag-and-drop events</a>.</p>
<!--START complete-->
<!--START websocket-api--><!--START storage--><!--START database--><!--START eventsource--><!--START workers-->
<!--START vocabs--><!--START vCard--><!--START vEvent--><!--START work-->
<h2 class="no-num" id="references">References</h2><!--REFS-->
<!--END vocabs--><!--END vCard--><!--END vEvent--><!--END work-->
<p>All references are normative unless marked "Non-normative".</p>
<!--START vocabs--><!--START vCard--><!--START vEvent--><!--START work-->
<dl>
<!--REFERENCES ON-->
<dt id="refsABNF">[ABNF]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/std/std68.txt">Augmented
BNF for Syntax Specifications: ABNF</a></cite>, D. Crocker,
P. Overell. IETF, January 2008.</dd>
<dt id="refsABOUT">[ABOUT]</dt>
<dd><cite><a
href="http://tools.ietf.org/html/draft-holsten-about-uri-scheme">The
'about' URI scheme</a></cite>, J. Holsten, L. Hunt. IETF, August
2009.</dd>
<dt id="refsARIA">[ARIA]</dt>
<dd><cite><a href="http://www.w3.org/WAI/PF/aria/">Accessible Rich
Internet Applications (WAI-ARIA)</a></cite>, J. Craig, M. Cooper, L. Pappas,
R. Schwerdtfeger, L. Seeman. W3C, August 2009.</dd>
<dt id="refsARIAIMPL">[ARIAIMPL]</dt>
<dd><cite><a
href="http://www.w3.org/WAI/PF/aria-implementation/">WAI-ARIA 1.0
User Agent Implementation Guide</a></cite>, A. Snow-Weaver,
M. Cooper. W3C, August 2009.</dd>
<dt id="refsATAG">[ATAG]</dt>
<dd>(Non-normative) <cite><a
href="http://www.w3.org/TR/ATAG20/">Authoring Tool Accessibility
Guidelines (ATAG) 2.0</a></cite>, J. Richards, J. Spellman,
J. Treviranus. W3C, May 2009.</dd>
<dt id="refsATOM">[ATOM]</dt>
<dd>(Non-normative) <cite><a
href="http://www.ietf.org/rfc/rfc4287.txt">The Atom Syndication
Format</a></cite>, M. Nottingham, R. Sayre. IETF, December
2005.</dd>
<dt id="refsBCP47">[BCP47]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/bcp/bcp47.txt">Tags for
Identifying Languages; Matching of Language Tags</a></cite>,
A. Phillips, M. Davis. IETF, September 2006.</dd>
<dt id="refsBECSS">[BECSS]</dt>
<dd><cite><a href="http://www.w3.org/TR/becss/">Behavioral
Extensions to CSS</a></cite>, I. Hickson. W3C, October 2007.</dd>
<dt id="refsBEZIER">[BEZIER]</dt>
<dd><cite>Courbes à poles</cite>, P. de Casteljau. INPI, 1959.</dd>
<dt id="refsBIDI">[BIDI]</dt>
<dd><cite><a href="http://www.unicode.org/reports/tr9/">UAX #9: Unicode
Bidirectional Algorithm</a></cite>, M. Davis. Unicode Consortium,
March 2008.</dd>
<dt id="refsBIG5">[BIG5]</dt>
<dd>(Non-normative) <cite>Chinese Coded Character Set in Computer</cite>. Institute
for Information Industry, March 1984.</dd>
<dt id="refsBOCU1">[BOCU1]</dt>
<dd>(Non-normative) <cite><a
href="http://www.unicode.org/notes/tn6/">UTN #6: BOCU-1:
MIME-Compatible Unicode Compression</a></cite>, M. Scherer,
M. Davis. Unicode Consortium, February 2006.</dd>
<dt id="refsCESU8">[CESU8]</dt>
<dd>(Non-normative) <cite><a
href="http://www.unicode.org/reports/tr26/">UTR #26: Compatibility
Encoding Scheme For UTF-16: 8-BIT (CESU-8)</a></cite>,
T. Phipps. Unicode Consortium, April 2002.</dd>
<dt id="refsCHARMOD">[CHARMOD]</dt>
<dd>(Non-normative) <cite><a
href="http://www.w3.org/TR/charmod/">Character Model for the World
Wide Web 1.0: Fundamentals</a></cite>, M. Dürst, F. Yergeau,
R. Ishida, M. Wolf, T. Texin. W3C, February 2005.</dd>
<dt id="refsCOMPUTABLE">[COMPUTABLE]</dt>
<dd>(Non-normative) <cite><a
href="http://www.turingarchive.org/browse.php/B/12">On computable
numbers, with an application to the
Entscheidungsproblem</a></cite>, A. Turing. In <cite>Proceedings of
the London Mathematical Society</cite>, series 2, volume 42, pages
230-265. London Mathematical Society, 1937. Retrieved on
2007-03-03.</dd>
<dt id="refsCOOKIES">[COOKIES]</dt>
<!--
<dd><cite><a href="http://www.ietf.org/rfc/rfc2109.txt">HTTP State
Management Mechanism</a></cite>, D. Kristol, L. Montulli. IETF,
February 1997.</dd>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2965.txt">HTTP State Management
Mechanism</a></cite>, D. Kristol, L. Montulli. IETF, October 2000.</dd>
-->
<dd><cite><a
href="http://tools.ietf.org/html/draft-abarth-cookie">HTTP State
Management Mechanism</a></cite>, A. Barth. IETF, August 2009.</dd>
<dt id="refsCORS">[CORS]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/cors/">Cross-Origin
Resource Sharing</a></cite>, A. van Kesteren. W3C, March 2009.</dd>
-->
<dd><cite><a
href="http://dev.w3.org/2006/waf/access-control/">Cross-Origin
Resource Sharing</a></cite>, A. van Kesteren. W3C, June 2009.</dd>
<dt id="refsCSS">[CSS]</dt>
<dd><cite><a href="http://www.w3.org/TR/CSS/">Cascading Style Sheets Level 2
Revision 1</a></cite>, B. Bos, T. Çelik, I.
Hickson, H. Lie. W3C, April 2009.</dd>
<dt id="refsCSSCOLOR">[CSSCOLOR]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/css3-color/">CSS Color
Module Level 3</a></cite>, T. Çelik, C. Lilley, L.
Baron. W3C, July 2008.</dd>
-->
<dd><cite><a href="http://dev.w3.org/csswg/css3-color/">CSS Color
Module Level 3</a></cite>, T. Çelik, C. Lilley, L.
Baron. W3C, August 2008.</dd>
<dt id="refsCSSFONTS">[CSSFONTS]</dt>
<dd><cite><a href="http://www.w3.org/TR/css3-fonts/">CSS Fonts
Module Level 3</a></cite>, J. Daggett. W3C, June 2009.</dd>
<dt id="refsCSSOM">[CSSOM]</dt>
<dd><cite><a href="http://dev.w3.org/csswg/cssom/">Cascading Style Sheets
Object Model (CSSOM)</a></cite>, A. van Kesteren. W3C, December 2007.</dd>
<dt id="refsCSSUI">[CSSUI]</dt>
<dd><cite><a href="http://www.w3.org/TR/css3-ui/">CSS3 Basic User
Interface Module</a></cite>, T. Çelik. W3C, May 2004.</dd>
<dt id="refsDOM2HTML">[DOM2HTML]</dt>
<dd>(Non-normative) <cite><a
href="http://www.w3.org/TR/DOM-Level-2-HTML/">Document Object Model
(DOM) Level 2 HTML Specification</a></cite>, J. Stenback, P. Le
Hegaret, A. Le Hors. W3C, January 2003.</dd>
<dt id="refsDOMCORE">[DOMCORE]</dt>
<dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
S. Byrnes. W3C, April 2004.</dd>
<!--
<dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
DOM Core</a></cite>, S. Pieters. W3C, June 2009.</dd>
-->
<dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
<!--
<dd><cite><a
href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
Model (DOM) Level 3 Events Specification</a></cite>,
B. Höhrmann, P. Le Hegaret, T. Pixley. W3C, December
2007.</dd>
-->
<dd><cite><a
href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
Object Model (DOM) Level 3 Events Specification</a></cite>,
D. Schepers. W3C, July 2009.</dd>
<dt id="refsDOMRANGE">[DOMRANGE]</dt>
<dd><cite><a
href="http://www.w3.org/TR/DOM-Level-2-Traversal-Range/">Document
Object Model (DOM) Level 2 Traversal and Range
Specification</a></cite>, J. Kesselman, J. Robie, M. Champion,
P. Sharpe, V. Apparao, L. Wood. W3C, November 2000.</dd>
<dt id="refsDOMVIEWS">[DOMVIEWS]</dt>
<dd><cite><a
href="http://www.w3.org/TR/DOM-Level-2-Views/">Document Object
Model (DOM) Level 2 Views Specification</a></cite>, A. Le Hors, L.
Cable. W3C, November 2000.</dd>
<dt id="refsE163">[E163]</dt>
<dd><cite>Recommendation E.163 — Numbering Plan for The International
Telephone Service</cite>, CCITT Blue Book, Fascicle II.2, pp. 128-134, November
1988.</dd>
<dt id="refsECMA262">[ECMA262]</dt>
<dd><cite><a
href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
Language Specification</a></cite>. ECMA, December 1999.</dd>
<dt id="refsECMA357">[ECMA357]</dt>
<dd>(Non-normative) <cite><a
href="http://www.ecma-international.org/publications/standards/Ecma-357.htm">ECMAScript
for XML (E4X) Specification</a></cite>. ECMA, December 2005.</dd>
<dt id="refsEUCKR">[EUCKR]</dt>
<dd><cite>Hangul Unix Environment</cite>. Korea Industrial
Standards Association, 1992. Ref. No. KS C 5861-1992.</dd>
<dt id="refsEVENTSOURCE">[EVENTSOURCE]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/eventsource/">Server-Sent
Events</a></cite>, I. Hickson. W3C, April 2009.</dd>
-->
<dd><cite><a
href="http://dev.w3.org/html5/eventsource/">Server-Sent
Events</a></cite>, I. Hickson. W3C, July 2009.</dd>
<dt id="refsFILEAPI">[FILEAPI]</dt>
<dd><cite><a
href="http://dev.w3.org/2006/webapi/FileUpload/publish/FileAPI.html">File
API</a></cite>, A. Ranganathan. W3C, August 2009.</dd>
<dt id="refsGBK">[GBK]</dt>
<dd><cite>Chinese Internal Code Specification</cite>. Chinese IT
Standardization Technical Committee, December 1995.</dd>
<!-- http://www.iana.org/assignments/charset-reg/GBK -->
<dt id="refsGRAPHICS">[GRAPHICS]</dt>
<dd>(Non-normative) <cite>Computer Graphics: Principles and
Practice in C</cite>, Second Edition, J. Foley, A. van Dam,
S. Feiner, J. Hughes. Addison-Wesley, July 1995. ISBN
0-201-84840-6.</dd>
<!--
This book ("Computer Graphics: Principles and Practice in C")
apparently does not make any references to literature in the
bibliographic section to define the "even-odd" rule for polygon
filling and hit testing. In the absence of such a reference, I
guess that this book is the most authoritative reference.
-->
<dt id="refsGREGORIAN">[GREGORIAN]</dt>
<dd>(Non-normative) <cite>Inter Gravissimas</cite>, A. Lilius,
C. Clavius. Gregory XIII Papal Bulls, February 1582.</dd>
<dt id="refsHTML4">[HTML4]</dt>
<dd>(Non-normative) <cite><a
href="http://www.w3.org/TR/html4/">HTML 4.01
Specification</a></cite>, D. Raggett, A. Le Hors, I. Jacobs. W3C,
December 1999.</dd>
<dt id="refsHTML5">[HTML5]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/html5/">HTML5</a></cite>,
I. Hickson, D. Hyatt. W3C, April 2009.</dd>
<dd><cite><a
href="http://www.w3.org/html/wg/html5/">HTML5</a></cite>,
I. Hickson, D. Hyatt. W3C, August 2009.</dd>
-->
<dd><cite><a
href="http://www.whatwg.org/specs/web-apps/current-work/">HTML5</a></cite>,
I. Hickson. WHATWG, August 2009.</dd>
<dt id="refsHTMLDIFF">[HTMLDIFF]</dt>
<!--
<dd>(Non-normative) <cite><a
href="http://www.w3.org/TR/html5-diff/">HTML5 differences from
HTML4</a></cite>, A. van Kesteren. W3C, April 2009.</dd>
-->
<dd>(Non-normative) <cite><a
href="http://dev.w3.org/html5/html4-differences/">HTML5
differences from HTML4</a></cite>, A. van Kesteren. W3C, August
2009.</dd>
<dt id="refsHTTP">[HTTP]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2616.txt">Hypertext
Transfer Protocol — HTTP/1.1</a></cite>, R. Fielding, J. Gettys,
J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee. IETF,
June 1999.</dd>
<dt id="refsIANACHARSET">[IANACHARSET]</dt>
<dd><cite><a
href="http://www.iana.org/assignments/character-sets">Character
Sets</a></cite>. IANA, May 2007.</dd>
<dt id="refsIANAPERMHEADERS">[IANAPERMHEADERS]</dt>
<dd><cite><a
href="http://www.iana.org/assignments/message-headers/perm-headers.html">Permanent
Message Header Field Names</a></cite>. IANA, October 2009.</dd>
<dt id="refsIEEE754">[IEEE754]</dt>
<dd><cite><a
href="http://ieeexplore.ieee.org/servlet/opac?punumber=4610933">IEEE
Standard for Floating-Point Arithmetic (IEEE 754)</a></cite>. IEEE,
August 2008. ISBN 978-0-7381-5753-5.</dd>
<dt id="refsISO8601">[ISO8601]</dt>
<dd><cite><a href="http://isotc.iso.org/livelink/livelink/4021199/ISO_8601_2004_E.zip?func=doc.Fetch&nodeid=4021199">ISO8601: Data elements and interchange formats — Information interchange — Representation of dates and times</a></cite>. ISO, December 2004.</dd>
<dt id="refsISO885911">[ISO885911]</dt>
<dd><cite><a
href="http://anubis.dkuug.dk/jtc1/sc2/open/02n3333.pdf">ISO-8859-11:
Information technology — 8-bit single-byte coded graphic
character sets — Part 11: Latin/Thai
alphabet</a></cite>. ISO, October 1999.</dd>
<dt id="refsJSON">[JSON]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc4627.txt">The
application/json Media Type for JavaScript Object Notation
(JSON)</a></cite>, D. Crockford. IETF, July 2006.</dd>
<dt id="refsJSURL">[JSURL]</dt>
<dd><cite><a
href="http://tools.ietf.org/html/draft-hoehrmann-javascript-scheme">The
'javascript' resource identifier scheme</a></cite>,
B. Höhrmann. IETF, November 2006.</dd>
<dt id="refsMAILTO">[MAILTO]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2368.txt">The mailto URL
scheme</a></cite>, P. Hoffman, L. Masinter, J. Zawinski.
IETF, July 1998.</dd>
<dt id="refsMATHML">[MATHML]</dt>
<dd><cite><a href="http://www.w3.org/TR/MathML/">Mathematical
Markup Language (MathML)</a></cite>, D. Carlisle, P. Ion, R. Miner,
N. Poppelier. W3C, October 2003.</dd>
<dt id="refsMIMESNIFF">[MIMESNIFF]</dt>
<dd><cite><a
href="http://tools.ietf.org/html/draft-abarth-mime-sniff">Content-Type
Processing Model</a></cite>, A. Barth, I. Hickson. IETF,
May 2009.</dd>
<dt id="refsMQ">[MQ]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/css3-mediaqueries/">Media
Queries</a></cite>, H. Lie, T. Çelik, D. Glazman, A. van
Kesteren. W3C, April 2009.</dd>
-->
<dd><cite><a
href="http://dev.w3.org/csswg/css3-mediaqueries/">Media
Queries</a></cite>, H. Lie, T. Çelik, D. Glazman, A. van
Kesteren. W3C, July 2009.</dd>
<dt id="refsNPAPI">[NPAPI]</dt>
<dd>(Non-normative) <cite><a
href="https://developer.mozilla.org/en/Gecko_Plugin_API_Reference">Gecko
Plugin API Reference</a></cite>. Mozilla, November 2008.</dd>
<dt id="refsOPENSEARCH">[OPENSEARCH]</dt>
<dd><cite><a
href="http://www.opensearch.org/Specifications/OpenSearch/1.1#Autodiscovery_in_HTML.2FXHTML">Autodiscovery
in HTML/XHTML</a></cite>. In <cite>OpenSearch 1.1 Draft 4</cite>,
Section 4.6.2. OpenSearch.org.</dd>
<dt id="refsORIGIN">[ORIGIN]</dt>
<dd><cite><a
href="http://tools.ietf.org/html/draft-abarth-origin">The HTTP
Origin Header</a></cite>, A. Barth, C. Jackson, I. Hickson. IETF,
September 2009.</dd>
<dt id="refsPINGBACK">[PINGBACK]</dt>
<dd><cite><a
href="http://www.hixie.ch/specs/pingback/pingback">Pingback
1.0</a></cite>, S. Langridge, I. Hickson. January 2007.</dd>
<dt id="refsPNG">[PNG]</dt>
<dd><cite><a href="http://www.w3.org/TR/PNG/">Portable Network
Graphics (PNG) Specification</a></cite>, D. Duce. W3C, November
2003.</dd>
<dt id="refsPORTERDUFF">[PORTERDUFF]</dt>
<dd><cite><a
href="http://keithp.com/~keithp/porterduff/p253-porter.pdf">Compositing
Digital Images</a></cite>, T. Porter, T. Duff. In <cite>Computer
graphics</cite>, volume 18, number 3, pp. 253-259. ACM Press, July
1984.</dd>
<dt id="refsPPUTF8">[PPUTF8]</dt>
<dd>(Non-normative) <cite><a
href="http://www.ifi.uzh.ch/mml/mduerst/papers/PDF/IUC11-UTF-8.pdf">The
Properties and Promises <!-- Promizes (sic) --> of
UTF-8</a></cite>, M. Dürst. University of Zürich,
September 1997. In <cite>Proceedings of the 11th International
Unicode Conference</cite>.</dd>
<dt id="refsPROGRESS">[PROGRESS]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/progress-events/">Progress
Events</a></cite>, C. McCathieNevile. W3C, May 2008.</dd>
-->
<dd><cite><a
href="http://dev.w3.org/2006/webapi/progress/Progress.html">Progress
Events</a></cite>, C. McCathieNevile. W3C, March 2009.</dd>
<dt id="refsPSL">[PSL]</dt>
<dd><cite><a href="http://publicsuffix.org/">Public Suffix List</a></cite>.
Mozilla Foundation.</dd>
<dt id="refsRFC1034">[RFC1034]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc1034.txt">Domain
Names - Concepts and Facilities</a></cite>, P. Mockapetris. IETF,
November 1987.</dd>
<dt id="refsRFC1345">[RFC1345]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc1345.txt">Character Mnemonics
and Character Sets</a></cite>, K. Simonsen. IETF, June 1992.</dd>
<dt id="refsRFC1468">[RFC1468]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc1468.txt">Japanese Character
Encoding for Internet Messages</a></cite>, J. Murai, M. Crispin, E. van der
Poel. IETF, June 1993.</dd>
<dt id="refsRFC1494">[RFC1494]</dt>
<dd>(Non-normative) <cite><a
href="http://www.ietf.org/rfc/rfc1494.txt">Equivalences between
1988 X.400 and RFC-822 Message Bodies</a></cite>, H. Alvestrand,
S. Thompson. IETF, August 1993.</dd>
<dt id="refsRFC1554">[RFC1554]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc1554.txt">ISO-2022-JP-2:
Multilingual Extension of ISO-2022-JP</a></cite>, M. Ohta, K. Handa. IETF,
December 1993.</dd>
<dt id="refsRFC1557">[RFC1557]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc1557.txt">Korean Character
Encoding for Internet Messages</a></cite>, U. Choi, K. Chon, H. Park. IETF,
December 1993.</dd>
<dt id="refsRFC1842">[RFC1842]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc1842.txt">ASCII
Printable Characters-Based Chinese Character Encoding for Internet
Messages</a></cite>, Y. Wei, Y. Zhang, J. Li, J. Ding, Y. Jiang.
IETF, August 1995.</dd>
<dt id="refsRFC1922">[RFC1922]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc1922.txt">Chinese Character
Encoding for Internet Messages</a></cite>, HF. Zhu, DY. Hu, ZG. Wang, TC. Kao,
WCH. Chang, M. Crispin. IETF, March 1996.</dd>
<dt id="refsRFC2045">[RFC2045]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2045.txt">Multipurpose Internet
Mail Extensions (MIME) Part One: Format of Internet Message Bodies</a></cite>,
N. Freed, N. Borenstein. IETF, November 1996.</dd>
<dt id="refsRFC2046">[RFC2046]</dt>
<dd><cite><a
href="http://www.ietf.org/rfc/rfc2046.txt">Multipurpose Internet
Mail Extensions (MIME) Part Two: Media Types</a></cite>, N. Freed,
N. Borenstein. IETF, November 1996.</dd> <!-- for text/plain and
"Internet Media type"; not for definition of "valid MIME type". -->
<dt id="refsRFC2119">[RFC2119]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF, March
1997.</dd>
<dt id="refsRFC2237">[RFC2237]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2237.txt">Japanese Character
Encoding for Internet Messages</a></cite>, K. Tamaru. IETF, November
1997.</dd>
<dt id="refsRFC2246">[RFC2246]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2246.txt">The TLS Protocol
Version 1.0</a></cite>, T. Dierks, C. Allen. IETF, January 1999.</dd>
<dt id="refsRFC2313">[RFC2313]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2313.txt">PKCS #1:
RSA Encryption</a></cite>, B. Kaliski. IETF, March 1998.</dd>
<dt id="refsRFC2318">[RFC2318]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2318.txt">The
text/css Media Type</a></cite>, H. Lie, B. Bos, C. Lilley. IETF,
March 1998.</dd>
<dt id="refsRFC2388">[RFC2388]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2388.txt">Returning Values from
Forms: multipart/form-data</a></cite>, L. Masinter. IETF, August 1998.</dd>
<dt id="refsRFC2426">[RFC2426]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2426.txt">vCard MIME Directory
Profile</a></cite>, F. Dawson, T. Howes. IETF, September 1998.</dd>
<dt id="refsRFC2445">[RFC2445]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2445.txt">Internet Calendaring
and Scheduling Core Object Specification (iCalendar)</a></cite>, F. Dawson, D.
Stenerson. IETF, November 1998.</dd>
<dt id="refsRFC2483">[RFC2483]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2483.txt">URI Resolution
Services Necessary for URN Resolution</a></cite>, M. Mealling, R. Daniel.
IETF, January 1999.</dd>
<dt id="refsRFC2781">[RFC2781]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2781.txt">UTF-16, an
encoding of ISO 10646</a></cite>, P. Hoffman, F. Yergeau. IETF,
February 2000.</dd>
<dt id="refsRFC2646">[RFC2646]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2646.txt">The Text/Plain Format
Parameter</a></cite>, R. Gellens. IETF, August 1999.</dd>
<dt id="refsRFC2806">[RFC2806]</dt>
<dd>(Non-normative) <cite><a
href="http://www.ietf.org/rfc/rfc2806.txt">URLs for Telephone
Calls</a></cite>, A. Vaha-Sipila. IETF, April 2000.</dd>
<dt id="refsRFC3023">[RFC3023]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc3023.txt">XML Media
Types</a></cite>, M. Murata, S. St. Laurent, D. Kohn. IETF, January 2001.</dd>
<dt id="refsRFC3279">[RFC3279]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc3279.txt">Algorithms
and Identifiers for the Internet X.509 Public Key Infrastructure
Certificate and Certificate Revocation List (CRL)
Profile</a></cite>, W. Polk, R. Housley, L. Bassham. IETF, April
2002.</dd>
<dt id="refsRFC3490">[RFC3490]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc3490.txt">Internationalizing
Domain Names in Applications (IDNA)</a></cite>, P. Faltstrom, P. Hoffman, A.
Costello. IETF, March 2003.</dd>
<dt id="refsRFC3548">[RFC3548]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc3548.txt">The Base16, Base32,
and Base64 Data Encodings</a></cite>, S. Josefsson. IETF, July
2003.</dd>
<dt id="refsRFC3629">[RFC3629]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc3629.txt">UTF-8, a
transformation format of ISO 10646</a></cite>, F. Yergeau. IETF,
November 2003.</dd>
<dt id="refsRFC3864">[RFC3864]</dt>
<dd><cite><a
href="http://www.ietf.org/rfc/rfc3864.txt">Registration Procedures
for Message Header Fields</a></cite>, G. Klyne, M. Nottingham,
J. Mogul. IETF, September 2004.</dd>
<dt id="refsRFC3986">[RFC3986]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc3986.txt">Uniform Resource
Identifier (URI): Generic Syntax</a></cite>, T. Berners-Lee, R. Fielding, L.
Masinter. IETF, January 2005.</dd>
<dt id="refsRFC3987">[RFC3987]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc3987.txt">Internationalized
Resource Identifiers (IRIs)</a></cite>, M. Dürst, M. Suignard. IETF, January
2005.</dd>
<dt id="refsRFC4281">[RFC4281]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc4281.txt">The Codecs Parameter
for "Bucket" Media Types</a></cite>, R. Gellens, D. Singer, P. Frojdh. IETF,
November 2005.</dd>
<dt id="refsRFC4329">[RFC4329]</dt>
<dd>(Non-normative) <cite><a
href="http://www.ietf.org/rfc/rfc4329.txt">Scripting Media
Types</a></cite>, B. Höhrmann. IETF, April 2006.</dd>
<dt id="refsRFC4366">[RFC4366]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc4366.txt">Transport
Layer Security (TLS) Extensions</a></cite>, S. Blake-Wilson,
M. Nystrom, D. Hopwood, J. Mikkelsen, T. Wright. IETF, April
2006.</dd>
<dt id="refsRFC4770">[RFC4770]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc4770.txt">vCard Extensions for
Instant Messaging (IM)</a></cite>, C. Jennings, J. Reschke. IETF,
January 2007.</dd>
<dt id="refsRFC5280">[RFC5280]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc5280.txt">Internet
X.509 Public Key Infrastructure Certificate and Certificate
Revocation List (CRL) Profile</a></cite>, D. Cooper, S. Santesson,
S. Farrell, S. Boeyen, R. Housley, W. Polk. IETF, May 2008.</dd>
<dt id="refsRFC5322">[RFC5322]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc5322.txt">Internet Message
Format</a></cite>, P. Resnick. IETF, October 2008.</dd>
<dt id="refsSCSU">[SCSU]</dt>
<dd>(Non-normative) <cite><a
href="http://www.unicode.org/reports/tr6/">UTR #6: A Standard
Compression Scheme For Unicode</a></cite>, M. Wolf, K. Whistler,
C. Wicksteed, M. Davis, A. Freytag, M. Scherer. Unicode Consortium,
May 2005.</dd>
<dt id="refsSELECTORS">[SELECTORS]</dt>
<dd><cite><a
href="http://www.w3.org/TR/css3-selectors">Selectors</a></cite>,
T. Çelik, E. Etemad, D. Glazman, I. Hickson, P. Linss,
J. Williams. W3C, March 2009.</dd>
<dt id="refsSHIFTJIS">[SHIFTJIS]</dt>
<dd><cite>JIS X0208: 7-bit and 8-bit double byte coded KANJI sets
for information interchange</cite>. Japanese Standards Association,
1997.</dd>
<dt id="refsSQL">[SQL]</dt>
<dd>The precise dialect has not yet been specified.</dd>
<dt id="refsSRGB">[SRGB]</dt>
<dd><cite><a
href="http://webstore.iec.ch/webstore/webstore.nsf/artnum/025408!OpenDocument&Click=">IEC
61966-2-1: Multimedia systems and equipment — Colour measurement
and management — Part 2-1: Colour management — Default RGB colour
space — sRGB</a></cite>. IEC, October 1999.</dd>
<dt id="refsSVG">[SVG]</dt>
<dd><cite><a href="http://www.w3.org/TR/SVGTiny12/">Scalable Vector
Graphics (SVG) Tiny 1.2 Specification</a></cite>, O. Andersson,
R. Berjon, E. Dahlström, A. Emmons, J. Ferraiolo, A. Grasso,
V. Hardy, S. Hayman, D. Jackson, C. Lilley, C. McCormack,
A. Neumann, C. Northway, A. Quint, N. Ramani, D. Schepers,
A. Shellshear. W3C, December 2008.</dd>
<dt id="refsTIS620">[TIS620]</dt>
<dd><cite><a
href="http://www.nectec.or.th/it-standards/std620/std620.htm">UDC
681.3.04:003.62</a></cite>. Thai Industrial Standards Institute,
Ministry of Industry, Royal Thai Government, 1990. ISBN
974-606-153-4.</dd>
<dt id="refsUAAG">[UAAG]</dt>
<dd>(Non-normative) <cite><a
href="http://www.w3.org/TR/UAAG20/">Web Content Accessibility
Guidelines (UAAG) 2.0</a></cite>, J. Allan, K. Ford, J. Richards,
J. Spellman. W3C, July 2009.</dd>
<dt id="refsUNICODE">[UNICODE]</dt>
<dd><cite><a href="http://www.unicode.org/versions/">The Unicode Standard</a></cite>. Unicode Consortium, 2007.</dd>
<dt id="refsUNIVCHARDET">[UNIVCHARDET]</dt>
<dd>(Non-normative) <cite><a
href="http://www.mozilla.org/projects/intl/UniversalCharsetDetection.html">A
composite approach to language/encoding
detection</a></cite>, S. Li, K. Momoi. Netscape, September 2001. In
<cite>Proceedings of the 19th International Unicode
Conference</cite>.</dd>
<dt id="refsUTF7">[UTF7]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2152.txt">UTF-7: A
Mail-Safe Transformation Format of Unicode</a></cite>,
D. Goldsmith, M. Davis. IETF, May 1997.</dd>
<dt id="refsUTF8DET">[UTF8DET]</dt>
<dd>(Non-normative) <cite><a
href="http://www.w3.org/International/questions/qa-forms-utf-8">Multilingual
form encoding</a></cite>, M. Dürst. W3C, October 2007.</dd>
<dt id="refsUTR36">[UTR36]</dt>
<dd>(Non-normative) <cite><a
href="http://www.unicode.org/reports/tr36/">UTR #36: Unicode
Security Considerations</a></cite>, M. Davis, M. Suignard. Unicode
Consortium, July 2008.</dd>
<dt id="refsWCAG">[WCAG]</dt>
<dd>(Non-normative) <cite><a
href="http://www.w3.org/TR/WCAG20/">Web Content Accessibility
Guidelines (WCAG) 2.0</a></cite>, B. Caldwell, M. Cooper, L. Reid,
G. Vanderheiden. W3C, December 2008.</dd>
<dt id="refsWEBADDRESSES">[WEBADDRESSES]</dt>
<dd><cite><a href="http://www.w3.org/html/wg/href/draft">Web
addresses in HTML5</a></cite>, D. Connolly,
C. Sperberg-McQueen. March 2009.</dd>
<dt id="refsWEBSQL">[WEBSQL]</dt>
<dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web SQL
Database</a></cite>, I. Hickson. W3C, July 2009.</dd>
<dt id="refsWEBIDL">[WEBIDL]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
IDL</a></cite>, C. McCormack. W3C, December 2008.</dd>
-->
<dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
IDL</a></cite>, C. McCormack. W3C, July 2009.</dd>
<dt id="refsWEBLINK">[WEBLINK]</dt>
<dd><cite><a
href="http://tools.ietf.org/html/draft-nottingham-http-link-header">Web
Linking</a></cite>, M. Nottingham. IETF, July 2009.</dd>
<dt id="refsWEBSOCKET">[WEBSOCKET]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/websockets/">The Web Sockets
API</a></cite>, I. Hickson. W3C, April
2009.</dd>
-->
<dd><cite><a href="http://dev.w3.org/html5/websockets/">The Web Sockets
API</a></cite>, I. Hickson. W3C, August
2009.</dd>
<dt id="refsWHATWGBLOG">[WHATWGBLOG]</dt>
<dd><cite><a href="http://blog.whatwg.org/">The WHATWG Blog</a></cite>. WHATWG.</dd>
<dt id="refsWHATWGWIKI">[WHATWGWIKI]</dt>
<dd><cite><a href="http://wiki.whatwg.org/">The WHATWG Wiki</a></cite>. WHATWG.</dd>
<dt id="refsWEBWORKERS">[WEBWORKERS]</dt>
<!--
<dd><cite><a
href="http://www.w3.org/TR/webworkers/">Workers</a></cite>,
I. Hickson. W3C, April 2009.</dd>
-->
<dd><cite><a href="http://dev.w3.org/html5/workers/">Web
Workers</a></cite>, I. Hickson. W3C, September 2009.</dd>
<dt id="refsWIN1252">[WIN1252]</dt>
<dd><cite><a href="http://www.microsoft.com/globaldev/reference/sbcs/1252.htm">Windows 1252</a></cite>. Microsoft.</dd>
<dt id="refsWIN1254">[WIN1254]</dt>
<dd><cite><a href="http://www.microsoft.com/globaldev/reference/sbcs/1254.htm">Windows 1254</a></cite>. Microsoft.</dd>
<dt id="refsWIN31J">[WIN31J]</dt>
<dd><cite><a href="http://www.microsoft.com/globaldev/reference/dbcs/932.mspx">Windows Codepage 932</a></cite>. Microsoft.</dd>
<dt id="refsWIN874">[WIN874]</dt>
<dd><cite><a href="http://www.microsoft.com/globaldev/reference/sbcs/874.mspx">Windows 874</a></cite>. Microsoft.</dd>
<dt id="refsWIN949">[WIN949]</dt>
<dd><cite><a href="http://www.microsoft.com/globaldev/reference/dbcs/949.mspx">Windows Codepage 949</a></cite>. Microsoft.</dd>
<dt id="refsX121">[X121]</dt>
<dd><cite>Recommendation X.121 — International Numbering Plan for
Public Data Networks</cite>, CCITT Blue Book, Fascicle VIII.3,
pp. 317-332, November 1988.</dd>
<dt id="refsX690">[X690]</dt>
<dd><cite><a
href="http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf">Recommendation
X.690 — Information Technology — ASN.1 Encoding Rules —
Specification of Basic Encoding Rules (BER), Canonical Encoding
Rules (CER), and Distinguished Encoding Rules
(DER)</a></cite>. International Telecommunication Union, July
2002.</dd>
<dt id="refsXHR">[XHR]</dt>
<!--
<dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
Object</a></cite>, A. van Kesteren. W3C, April
2008.</dd>
-->
<dd><cite><a
href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
A. van Kesteren. W3C, June 2009.</dd>
<dt id="refsXHTML1">[XHTML1]</dt>
<dd><cite><a href="http://www.w3.org/TR/xhtml1/">XHTML(TM) 1.0 The
Extensible HyperText Markup Language (Second Edition)</a></cite>. W3C,
August 2002.</dd>
<dt id="refsXHTMLMOD">[XHTMLMOD]</dt>
<dd><cite><a
href="http://www.w3.org/TR/xhtml-modularization">Modularization of
XHTML(TM)</a></cite>, M. Altheim, F. Boumphrey, S. Dooley, S.
McCarron, S. Schnitzenbaumer, T. Wugofski. W3C, April 2001.</dd>
<dt id="refsXML">[XML]</dt>
<dd><cite><a href="http://www.w3.org/TR/xml/">Extensible Markup
Language</a></cite>, T. Bray, J. Paoli, C. Sperberg-McQueen,
E. Maler, F. Yergeau. W3C, November 2008.</dd>
<dt id="refsXMLBASE">[XMLBASE]</dt>
<dd><cite><a href="http://www.w3.org/TR/xmlbase/">XML
Base</a></cite>, J. Marsh, R. Tobin. W3C, January 2009.</dd>
<dt id="refsXMLNS">[XMLNS]</dt>
<dd><cite><a href="http://www.w3.org/TR/xml-names/">Namespaces in
XML</a></cite>, T. Bray, D. Hollander, A. Layman, R. Tobin. W3C,
August 2006.</dd>
<dt id="refsXPATH10">[XPATH10]</dt>
<dd><cite><a
href="http://www.w3.org/TR/1999/REC-xpath-19991116">XML Path
Language (XPath) Version 1.0</a></cite>, J. Clark, S. DeRose. W3C,
November 1999.</dd>
<dt id="refsXSLT10">[XSLT10]</dt>
<dd><cite><a href="http://www.w3.org/TR/1999/REC-xslt-19991116">XSL
Transformations (XSLT) Version 1.0</a></cite>, J. Clark. W3C,
November 1999.</dd>
<!--REFERENCES OFF-->
</dl>
<!--END vocabs--><!--END vCard--><!--END vEvent--><!--END work-->
<!--END websocket-api--><!--END storage--><!--END database--><!--END eventsource--><!--END workers-->
<h2 class="no-num">Acknowledgements</h2> <!-- ACKS -->
<p>Thanks to
Aankhen,
Aaron Boodman,
Aaron Leventhal,
Adam Barth,
Adam de Boor,
Adam Roben,
Addison Phillips,
Adele Peterson,
Adrian Bateman,
Adrian Sutton,
Agustín Fernández,
Ajai Tirumali,
Alan Plum,
Alastair Campbell,
Alex Bishop,
Alex Nicolaou,
Alex Rousskov,
Alexander J. Vincent,
Alexey Feldgendler,
Алексей Проскуряков (Alexey Proskuryakov),
Alexis Deveria,
Allan Clements,
Amos Jeffries,
Anders Carlsson,
Andreas<!-- mqmq87 -->,
Andrei Popescu,
André E. Veltstra,
Andrew Clover,
Andrew Gove,
Andrew Grieve,
Andrew Oakley,
Andrew Sidwell,
Andrew Smith,
Andrew W. Hagen,
Andy Heydon,
Andy Palay,
Anne van Kesteren,
Anthony Boyd,
Anthony Bryan,
Anthony Hickson,
Anthony Ricaud,
Antti Koivisto,
Aron Spohr,
Arphen Lin,
Aryeh Gregor,
Asbjørn Ulsberg,
Ashley Sheridan,
Aurelien Levy,
Ave Wrigley,
Ben Boyle,
Ben Godfrey,
Ben Leslie,
Ben Meadowcroft,
Ben Millard,
Benjamin Hawkes-Lewis,
Bert Bos,
Bijan Parsia,
Bil Corry,
Bill Mason,
Bill McCoy,
Billy Wong,
Björn Höhrmann,
Blake Frantz,
Boris Zbarsky,
Brad Fults,
Brad Neuberg,
Brady Eidson,
Brendan Eich,
Brenton Simpson,
Brett Wilson,
Brett Zamir,
Brian Campbell,
Brian Korver,
Brian Ryner,
Brian Smith,
Brian Wilson,
Bryan Sullivan,
Bruce D'Arcus,
Bruce Lawson,
Bruce Miller,
C. Williams,
Cameron McCormack,
Cao Yipeng,
Carlos Perelló Marín,
Chao Cai,
윤석찬 (Channy Yun),
Charl van Niekerk,
Charles Iliya Krempeaux,
Charles McCathieNevile,
Chris Cressman,
Chris Morris,
Chris Pearce,
Christian Biesinger,
Christian Johansen,
Christian Schmidt,
Christopher Aillon,
Chriswa,
Cole Robison,
Colin Fine,
Collin Jackson,
Corprew Reed,
Craig Cockburn,
Csaba Gabor,
Daniel Barclay,
Daniel Bratell,
Daniel Brooks,
Daniel Brumbaugh Keeney,
Daniel Davis,
Daniel Glazman,
Daniel Peng,
Daniel Schattenkirchner,
Daniel Spång,
Daniel Steinberg,
Danny Sullivan,
Darin Adler,
Darin Fisher,
Darxus,
Dave Camp,
Dave Hodder,
Dave Lampton,
Dave Singer,
Dave Townsend<!-- Mossop on moz irc -->,
David Baron,
David Bloom,
David Bruant,
David Carlisle,
David E. Cleary,
David Egan Evans,
David Flanagan,
David Gerard,
David Håsäther,
David Hyatt,
David I. Lehn,
David Matja,
David Remahl,
David Smith,
David Woolley,
DeWitt Clinton,
Dean Edridge,
Dean Edwards,
Debi Orton,
Derek Featherstone,
Dimitri Glazkov,
Dimitry Golubovsky,
Divya Manian,
dolphinling,
Dominique Hazaël-Massieux,
Doron Rosenberg,
Doug Kramer,
Drew Wilson,
Edmund Lai,
Eduard Pascual,
Eduardo Vela,
Edward O'Connor,
Edward Welbourne,
Edward Z. Yang,
Eira Monstad,
Eliot Graff,
Elizabeth Castro,
Elliott Sprehn,
Elliotte Harold,
Eric Carlson,
Eric Law,
Eric Rescorla,
Erik Arvidsson,
Evan Martin,
Evan Prodromou,
Evert,
fantasai,
Felix Sasaki,
Francesco Schwarz,
Francis Brosnan Blazquez,
Franck 'Shift' Quélain,
Frank Barchard,
鵜飼文敏 (Fumitoshi Ukai),
Futomi Hatano,
Gavin Carothers,
Gareth Rees,
Garrett Smith,
Geoffrey Garen,
Geoffrey Sneddon,
George Lund,
Giovanni Campagna,
Graham Klyne,
Greg Botten,
Greg Houston,
Gregg Tavares,
Grey,
Gytis Jakutonis,
Håkon Wium Lie,
Hallvord Reiar Michaelsen Steen,
Hans S. Tømmerhalt,
Henri Sivonen,
Henrik Lied,
Henry Mason,
Hugh Winkler,
Ian Bicking,
Ian Davis,
Ignacio Javier,
Ivan Enderlin,
Ivo Emanuel Gonçalves,
J. King,
Jacques Distler,
James Craig,
James Graham,
James Justin Harrell,
James M Snell,
James Perrett,
James Robinson,
Jan-Klaas Kollhof,
Jason Kersey,
Jason Lustig,
Jason White,
Jasper Bryant-Greene,
Jed Hartman,
Jeff Balogh,
Jeff Cutsinger,
Jeff Schiller,
Jeff Walden,
Jeffrey Zeldman,
胡慧鋒 (Jennifer Braithwaite),
Jens Bannmann,
Jens Fendler,
Jens Lindström,
Jens Meiert,
Jeremy Keith,
Jeremy Orlow,
Jeroen van der Meer,
Jian Li,
Jim Jewett,
Jim Ley,
Jim Meehan,
Jjgod Jiang,
João Eiras,
Joe Clark,
Joe Gregorio,
Joel Spolsky,
Johan Herland,
John Boyer,
John Bussjaeger,
John Carpenter,
John Fallows,
John Foliot,
John Harding,
John Keiser,
John Snyders,
John-Mark Bell,
Johnny Stenback,
Jon Ferraiolo,
Jon Gibbins,
Jon Perlow,
Jonas Sicking,
Jonathan Rees,
Jonathan Worent,
Jonny Axelsson,
Jorgen Horstink,
Jorunn Danielsen Newth,
Joseph Kesselman,
Joseph Pecoraro,
Josh Aas,
Josh Levenberg,
Joshua Randall,
Jukka K. Korpela,
Jules Clément-Ripoche,
Julian Reschke,
Justin Sinclair,
Kai Hendry,
Kartikaya Gupta,
Kathy Walton,
Kelly Norton,
Kevin Benson,
Kornél Pál,
Kornel Lesinski,
Kristof Zelechovski,
黒澤剛志 (KUROSAWA Takeshi),
Kyle Hofmann<!-- Ozob -->,
Léonard Bouchet,
Lachlan Hunt,
Larry Masinter,
Larry Page,
Lars Gunther<!-- Keryx Web -->,
Lars Solberg,
Laura Granka,
Laura L. Carlson,
Laura Wisewell,
Laurens Holst,
Lee Kowalkowski,
Leif Halvard Silli,
Lenny Domnitser,
Leons Petrazickis,
Logan<!-- on moz irc -->,
Loune,
Luke Kenneth Casson Leighton,
Maciej Stachowiak,
Magnus Kristiansen<!-- Dashiva -->,
Maik Merten,
Malcolm Rowe,
Mark Birbeck,
Mark Miller,
Mark Nottingham,
Mark Pilgrim,
Mark Rowe<!--bdash-->,
Mark Schenk,
Mark Wilton-Jones,
Martijn Wargers,
Martin Atkins,
Martin Dürst,
Martin Honnen,
Martin Kutschker,
Masataka Yakura,
Mathieu Henri,
Matt Schmidt,
Matt Wright,
Matthew Gregan,
Matthew Mastracci,
Matthew Raymond,
Matthew Thomas,
Mattias Waldau,
Max Romantschuk,
Menno van Slooten,
Micah Dubinko,
Michael 'Ratt' Iannarelli,
Michael A. Nachbaur,
Michael A. Puls II<!--Shadow2531-->,
Michael Carter,
Michael Daskalov,
Michael Enright,
Michael Gratton,
Michael Nordman,
Michael Powers,
Michael(tm) Smith,
Michel Fortin,
Michelangelo De Simone,
Michiel van der Blonk,
Mihai Şucan<!-- from ROBO Design -->,
Mike Brown,
Mike Dierken<!-- S. Mike Dierken -->,
Mike Dixon,
Mike Schinkel,
Mike Shaver,
Mikko Rantalainen,
Mohamed Zergaoui<!-- Innovimax SARL -->,
Ms2ger,
NARUSE Yui,
Neil Deakin,
Neil Rashbrook,
Neil Soiffer,
Nicholas Shanks,
Nicolas Gallagher,
Noah Mendelsohn,
Noah Slater,
Ojan Vafai,
Olaf Hoffmann,
Olav Junker Kjær,
Oldřich Vetešník,
Oliver Hunt,
Oliver Rigby,
Olivier Gendrin,
Olli Pettay,
Patrick H. Lauke,
Paul Norman,
Per-Erik Brodin,
Peter Karlsson,
Peter Kasting,
Peter Stark,
Peter-Paul Koch,
Philip Jägenstedt,
Philip Taylor,
Philip TAYLOR<!-- a different one -->,
Prateek Rungta,
Rachid Finge,
Rajas Moonka,
Ralf Stoltze,
Ralph Giles,
Raphael Champeimont,
Remco,
Remy Sharp,
Rene Saarsoo,
Rene Stach,
Ric Hardacre,
Rich Doughty,
Richard Ishida,
Rigo Wenning,
Rikkert Koppes,
Rimantas Liubertas,
Rob Ennals,
Robert Blaut,
Robert Collins,
Robert O'Callahan,
Robert Sayre,
Robin Berjon,
Roland Steiner,
Roman Ivanov,
Roy Fielding,
Ryan King,
S. Mike Dierken,
Sam Dutton,
Sam Kuper,
Sam Ruby,
Sam Weinig,
Sander van Lambalgen,
Sarven Capadisli,
Scott González,
Scott Hess,
Sean Fraser,
Sean Hogan,
Sean Knapp,
Sebastian Markbåge,
Sebastian Schnitzenbaumer,
Seth Call,
Shanti Rao,
Shaun Inman,
Shiki Okasaka,
Sierk Bornemann,
Sigbjørn Vik,
Silvia Pfeiffer,
Simon Montagu,
Simon Pieters,
Simon Spiegel,
skeww, <!-- on reddit -->
Stefan Haustein,
Stefan Santesson,
Steffen Meschkat,
Stephen Ma,
Steve Faulkner,
Steve Runyon,
Steven Bennett,
Steven Garrity,
Steven Tate,
Stewart Brodie,
Stuart Ballard,
Stuart Parmenter,
Subramanian Peruvemba,
Sunava Dutta,
Susan Borgrink,
Susan <!--G.--> Lesch,
Sylvain Pasche,
T. J. Crowder,
<span title="" lang="tr">Tantek Çelik</span>,
田村健人 (TAMURA Kent),
Ted Mielczarek,
Terrence Wood,
Thomas Broyer,
Thomas O'Connor,
Tim Altman,
Tim Johansson,
Toby Inkster,
Todd Moody,
Tom Pike,
Tommy Thorsen,
Travis Leithead,
Tyler Close,
Vladimir Katardjiev,
Vladimir Vukićević,
voracity,
Wakaba,
Wayne Pollock,
Wellington Fernando de Macedo,
Will Levine,
William Swanson,
Wladimir Palant,
Wojciech Mach,
Wolfram Kriesing,
Yi-An Huang,
Yngve Nysaeter Pettersen,
Yuzo Fujishima,
Zhenbin Xu,
Zoltan Herczeg,
and
Øistein E. Andersen,
for their useful comments, both large and small, that have led to
changes to this specification over the years.</p>
<p>Thanks also to everyone who has ever posted about HTML5 to their
blogs, public mailing lists, or forums, including the <a
href="http://lists.w3.org/Archives/Public/public-html/">W3C
public-html list</a> and the <a
href="http://www.whatwg.org/mailing-list">various WHATWG lists</a>.
<p>Special thanks to Richard Williamson for creating the first
implementation of <code>canvas</code> in Safari, from which the
canvas feature was designed.</p>
<p>Special thanks also to the Microsoft employees who first
implemented the event-based drag-and-drop mechanism, <code
title="attr-contenteditable">contenteditable</code>, and other
features first widely deployed by the Windows Internet Explorer
browser.</p>
<p>Thanks to the participants of the microdata usability study for
allowing us to use their mistakes as a guide for designing the
microdata feature.</p>
<div class="impl">
<p>Special thanks and $10,000 to David Hyatt who came up with a
broken implementation of the <a href="#adoptionAgency">adoption
agency algorithm</a> that the editor had to reverse engineer and fix
before using it in the parsing section.</p>
</div>
<p>Thanks to the many sources that provided inspiration for the
examples used in the specification.</p>
<!--END html--><!--END html5-->
<div itemscope itemtype="http://n.whatwg.org/work">
<p>The abstract is based on <a itemprop="work" href="http://www.flickr.com/photos/wonderlane/2986252088/">a photo</a>
by <a itemprop="http://creativecommons.org/ns#attributionURL" href="http://www.flickr.com/photos/wonderlane/">Wonderlane</a>.
(<a itemprop="license" href="http://creativecommons.org/licenses/by/2.0/">CC BY 2.0</a>)
</div>
<!--START html--><!--START html5-->
<p>Thanks also to the Microsoft blogging community for some ideas,
to the attendees of the W3C Workshop on Web Applications and
Compound Documents for inspiration, to the #mrt crew, the #mrt.no
crew, and the #whatwg crew, and to Pillar and Hedral for their ideas
and support.</p>
<!-- Hopefully Kam won't notice he's covered by these
acknowledgements three times! -->
<!--
v2 * library of resources:
var library = new ZipFile("data.zip");
library.onload = function() {
var sound1 = library.getAudio("sound1.wav"); // returns an Audio object
var image1 = library.getImage("image1.png"); // returns an HTMLImageElement
var doc1 = library.getXMLDocument("doc1.xml"); // returns a Document
var doc2 = library.getHTMLDocument("doc1.html"); // returns an HTMLDocument
}
or:
var library = new ResourceLoader("data.zip");
library.add("moredata.zip");
library.onload = function() { ... }
library.onloading = function() {
reportLoadProgress(library.progress); // 0.0 .. 1.0
}
or:
var library = new AudioZip("sounds.zip");
library.onload = function() {
var sound1 = library["sound1.wav"];
sound.play();
}
v2 * [onclick] should make element focusable; enter should send onclick ?
v2 * a fairly common situation for web authors is to have two lists, where
the contents of the second depends on the value of the first. Is there
any way we could extend the current model to include this functionality?
(e.g. bugzilla product/component ui)
v2 * quick-searchable select
v2 * include/exclude selectors (two multi-select columns with arrows to
move selected items) and that sort of thing.
http://slashdot.org/comments.pl?sid=110240&cid=9357022
v2 * Oh, and forms need a standardized Help widget/icon. I know I can
turn my cursor into a question mark, but I'm looking for something
simple and pervasive. Maybe you can wrap fields in a help tag, just
as you do for fieldsets. And in that help tag, attributes are
available that allow for a nice, formatted, clean, full help text
popup/area/thing.
http://slashdot.org/comments.pl?sid=110240&cid=9359006
v2 * Validating only part of a form. - Anja Lehmann
v2 * Reminder to add a way to expose access keys in buttons, i.e.
Sub&mit where & signifies the m is the access key to use. Possibly
automatic? <input accesskey="m" value="Submit"> browser would be
smart enough to underline the first instance of the access key if
it exists (case insensitive)? - kerz
[or deprecate the lot (->web apps)]
v2 * need an attribute that says "the children of this element are in
their own tabbing universe, tabindex should be relative to each
other, not to the document"
-> web apps?
v2 * make select widgets have multiple columns
or ->web apps with list view
v2 * required as a group (one of the following must be available):
+ i propose something like the following:
<input type="text" group="contact" name="voicephone"> Voice phone
<input type="text" group="contact" name="fax"> Fax
<input type="text" group="contact" name="mobile"> Mobile phone
<input type="text" group="contact" name="email"> E-mail
if the user fills out none of the form fields in the "contact"
group, an error message is shown and the form is not submitted.
- Peter-Paul Koch
v2 * formatting of number fields, text fields, etc, so that when the
field is not focused, the value is displayed differently. Seems
like this would also be useful e.g. for <output> or something so
you can display localised dates, etc.
v2 * being able to select date range (from day x to day y)
v2 * ways of visualizing a linefeed in a <textarea> so it looks different
from wrapping text
v2 * all login systems have
1. enter username and password
2. create new account
3. lost password
some way of integrating this into one system, since it's so common
v2 * way of identifying different sorts of mailadresses
a) mailing-list
b) person
c) department in a company ("support", "marketing" and such)
d) general mail (like "info", "mail", "contact" and such)
e) other sorts of groupings
(or ->web apps; this is talking about in mailto: links, I think)
v2 * hotswapping login identities like in windows xp
you are logged in on operamail.com, and you want to check the mail
of another user. somehow, combined with the wand or whatever,
the browser will remember the login page, and it can re-submit it
without having to load the initial page (saving time)
v2 * provide different measuring systems, like having the html indicate
fluid in both fluid ounces and liters, and the browser can display
one or the other based on regional settings in the browser or ui,
display conversions in a tooltip, or let the user decide which
format to display.
v2 * indicate "x days ago" or "y days into the future" rather than date
v2 * input control for anniversaries
v2 * only submit fields that have changed, or a way to include in the
submission a list of which form controls were changed from their
default value
v2 * have a way of marking the first option of a <select> as the default
but have it not satisfy a new required="" attribute on <select> so
that you can have selects that require a valid value.
v2 * type="time" value="now"
v2 * add something to type="number" to support basic currency and unit
formatting of input
v2 * <fieldset enabled-if-checked="myCheckboxOrRadioButton">
...to allow sections to only be enabled if a radio button makes it
relevant, for instance.
v2 * Yan Morin proposed a multi-column dropdown <select> or <datalist>:
_________________
|_New_York______|V|_________________ <- input with a table link and a down arrow
|_City__________|_State_|_Country_|_| <- header of the table
| Montreal | QC | Canada |A| <- top arrow of the scroll
|>New York <| NY | US | | <- selected row
| Washington | DC | US |X| <- cursor scroll
| San Francisco | CA | US | |
|_Toronto_______|__ON___|_Canada__|V| <- bottom arrow of the scroll
v2 * add for="" attribute to <input type="password"> so that you can
link usernames and passwords. (Jonas Sicking)
v2 * value for unchecked checkbox?
v2 * A way to specify the default button - Michael Gratton
v2 * <fieldset readonly>?
v2 * dolphinling suggests having a way to mark certain parts of a
form as being dependent on another (mutually exclusive parts of
a form)
v2 * expose the form data set, either as an object (on which one can
invoke the JSON serialiser), or in the form of a method on
HTMLFormElement that returns the form data set serialised
according to a particular encoding (defaulting to the form's
enctype="" one, probably). This would allow forms to be used
with XHR-like systems without having to manually construct the
form data set the way that is done today.
Consistency in editorial style:
v2 * need to become consistent about whether or not to quote keyword
("<code title="">foo</code>" vs <code>foo</code>)
v2 * make the spec consistent about whether the word "algorithm" is part of
an algorithm's name or not ("</dfn> algorithm", "</span> algorithm")
v2 * make the spec more consistent about its use of "hexadecimal"
and "base-sixteen", the order that 0-9 A-Z a-z is mentioned,
and the detail to which the spec explains how to interpret a
string as a hexadecimal number.
v2 * become more consistent about what markup we use to mark up
productions (nothing? <i>? <code>?)
v2 * use <code>Document</code> consistently instead of 'document'.
v2 * s/raise/throw/g
v2 * be clearer about arrays/lists/collections being zero-based
despite using the term "/index/th".
v2 * use the sample widgets:
<li><img alt="A text field with editable sections for each
value, with a button to pop up a dialog showing a calendar or
clock." src="sample-datetime-ui-2"></li>
<li><img alt="A calendar grid with a clock in the upper right
hand corner." src="sample-datetime-ui-3"></li>
-->
</body>
</html>
<!--END html--><!--END html5-->
<!--END complete-->