or <description> MUST be present. inSpecs: - RSS 2.0 schemaOrg: Article related: - Entry - Channel - GUID - term: Entry definition: >- The Atom 1.0 unit of syndicated content inside a feed. Each atom:entry MUST have id, title, and updated; author may be inherited from the parent feed; either content or an alternate link is required. inSpecs: - Atom 1.0 schemaOrg: Article required: - id - title - updated - term: Content definition: >- The body of an item or entry. In Atom, atom:content may be text, html, xhtml, or reference remote content via src. In JSON Feed, an item MUST supply at least one of content_html or content_text. inSpecs: - Atom 1.0 - JSON Feed 1.1 schemaOrg: articleBody - term: Summary definition: >- Short representation of an entry's content. Required in Atom when atom:content is base64-encoded, references remote content, or is absent in favor of a link. inSpecs: - Atom 1.0 - JSON Feed 1.1 schemaOrg: abstract identity: - term: GUID definition: >- Globally unique identifier for an RSS 2.0 item. When isPermaLink='true' (default) the value MUST be a resolvable URL. Best practice per the RSS Best Practices Profile is to provide a stable opaque identifier and set isPermaLink='false', commonly using the Tag URI scheme (RFC 4151). inSpecs: - RSS 2.0 - RSS Best Practices Profile schemaOrg: identifier aliases: - Globally Unique Identifier related: - Tag URI - term: ID definition: >- Atom 1.0 atom:id — permanent, universally unique identifier for a feed or entry as an IRI. In JSON Feed, item.id SHOULD be a URL that resolves to the item's permalink. inSpecs: - Atom 1.0 - JSON Feed 1.1 schemaOrg: identifier required: true - term: PermaLink definition: >- Permanent URL for an item or entry. In RSS 2.0 the <link> element of an item serves as the permalink; an item's guid is a permalink when isPermaLink='true'. inSpecs: - RSS 2.0 - Atom 1.0 - JSON Feed 1.1 schemaOrg: url - term: Tag URI definition: >- An identifier scheme (RFC 4151) of the form 'tag:authority,YYYY-MM-DD:specific-string' often used as a stable non-URL guid for RSS items to avoid coupling identity to URL changes. inSpecs: - RSS Best Practices Profile related: - GUID dates: - term: pubDate definition: >- Publication date of an RSS 2.0 channel or item, formatted per RFC 822. Aggregators do not honor future-dated pubDate — items SHOULD NOT be published with a future pubDate to attempt embargo. inSpecs: - RSS 2.0 - RSS Best Practices Profile schemaOrg: datePublished - term: lastBuildDate definition: >- RSS 2.0 channel-level RFC 822 timestamp of the last time the channel's content changed. inSpecs: - RSS 2.0 schemaOrg: dateModified - term: updated definition: >- Atom 1.0 atom:updated — most recent instant when the feed or entry was meaningfully modified, as an RFC 3339 timestamp. inSpecs: - Atom 1.0 schemaOrg: dateModified required: true - term: published definition: >- Atom 1.0 atom:published — initial creation or first availability of an entry, as an RFC 3339 timestamp. inSpecs: - Atom 1.0 schemaOrg: datePublished - term: date_published definition: >- JSON Feed 1.1 RFC 3339 timestamp of an item's original publication. inSpecs: - JSON Feed 1.1 schemaOrg: datePublished - term: date_modified definition: >- JSON Feed 1.1 RFC 3339 timestamp of an item's last modification. inSpecs: - JSON Feed 1.1 schemaOrg: dateModified enclosures-and-media: - term: Enclosure definition: >- An RSS 2.0 media attachment on an item, with url, length (bytes), and type (MIME) attributes. The foundation of podcasting. Best practice is no more than one enclosure per item because not all aggregators handle multiple enclosures. inSpecs: - RSS 2.0 - RSS Best Practices Profile schemaOrg: associatedMedia related: - Attachment - Media RSS - term: Attachment definition: >- JSON Feed 1.1 item-level media attachment with url, mime_type, optional title, size_in_bytes, and duration_in_seconds. inSpecs: - JSON Feed 1.1 schemaOrg: associatedMedia - term: Media RSS definition: >- A widely-used XML namespace extension to RSS 2.0 (http://search.yahoo.com/mrss/) for richer media metadata than the single-enclosure model — multiple media:content nodes, thumbnails, ratings, credits. inSpecs: - Media RSS (extension) related: - Enclosure subscription: - term: OPML definition: >- Outline Processor Markup Language — an XML format whose most common application is exchanging lists of RSS/Atom/JSON Feed subscriptions between feed readers. Subscription-list outlines use type='rss' with xmlUrl pointing to the feed and htmlUrl pointing to the site. inSpecs: - OPML 2.0 aliases: - Outline Processor Markup Language - term: Subscription List definition: >- An OPML 2.0 document whose body contains outline elements representing a user's feed subscriptions, optionally nested into folder outlines. The de facto portable format for feed-reader import/export. inSpecs: - OPML 2.0 related: - OPML - Outline - term: Outline definition: >- The fundamental OPML element; for subscription lists, a leaf outline represents one feed subscription via type='rss', text, title, xmlUrl, and htmlUrl. inSpecs: - OPML 2.0 discovery: - term: Autodiscovery definition: >- HTML convention by which a web page advertises its feed(s) via <link rel='alternate' type='application/rss+xml' href='...'> elements in the document head. Feed readers, browsers, and crawlers use this to locate feeds from a homepage URL alone. The same pattern is used with application/atom+xml and application/feed+json. inSpecs: - HTML - RSS Best Practices Profile related: - Self Link - .well-known/feeds - term: Self Link definition: >- An atom:link with rel='self' pointing at the feed's own canonical URL. Required for proper feed identity and relocation across the Atom ecosystem; widely adopted in RSS 2.0 via the Atom namespace as well. inSpecs: - Atom 1.0 related: - feed_url - term: feed_url definition: >- JSON Feed 1.1 top-level URL identifying the feed itself; the JSON Feed equivalent of atom:link rel='self'. Strongly recommended for public feeds because it enables relocation. inSpecs: - JSON Feed 1.1 - term: home_page_url definition: >- JSON Feed 1.1 top-level URL identifying the human-readable website the feed describes — the equivalent of RSS 2.0 channel <link>. inSpecs: - JSON Feed 1.1 push-and-real-time: - term: WebSub definition: >- W3C Recommendation (formerly PubSubHubbub) defining a publish/subscribe protocol over HTTP that turns pull-based feeds into push-based ones. JSON Feed 1.1 surfaces WebSub hubs via the top-level 'hubs' array; Atom and RSS surface them via <link rel='hub' href='...'> elements. inSpecs: - WebSub (W3C) - JSON Feed 1.1 - Atom 1.0 - RSS 2.0 related: - Hub - term: Hub definition: >- A WebSub hub URL advertised by a feed to which subscribers can subscribe to receive real-time notifications when the feed changes, avoiding pure polling. inSpecs: - WebSub - JSON Feed 1.1 related: - WebSub - term: rssCloud definition: >- The original RSS 2.0 <cloud> element predating WebSub, declaring a service that aggregators can register with to be notified of channel updates. Limited adoption today. inSpecs: - RSS 2.0 extensions: - term: XML Namespace Extension definition: >- The standard mechanism for extending RSS 2.0 and Atom feeds without changing the core spec — declare a new XML namespace and add elements from that namespace alongside core ones. RSS 2.0's frozen status makes namespaces the only path for new features. inSpecs: - RSS 2.0 - Atom 1.0 related: - Media RSS - iTunes Podcast Namespace - Dublin Core - term: iTunes Podcast Namespace definition: >- Apple's RSS 2.0 namespace extension (http://www.itunes.com/dtds/podcast-1.0.dtd) defining the de facto podcast metadata vocabulary — itunes:author, itunes:category, itunes:explicit, itunes:image, itunes:duration, itunes:summary. inSpecs: - iTunes Podcast Namespace (extension) - term: Dublin Core definition: >- A widely-used metadata namespace (http://purl.org/dc/elements/1.1/) embedded in many RSS 2.0 feeds for canonical metadata like dc:creator and dc:date. inSpecs: - Dublin Core - RSS 2.0 (via extension) media-types: - term: application/rss+xml definition: >- IANA-registered MIME type for RSS 2.0 feeds. Used as the value of the type attribute in autodiscovery <link> elements and as the Content-Type response header when serving RSS feeds. inSpecs: - RSS 2.0 - term: application/atom+xml definition: >- IANA-registered MIME type for Atom 1.0 feeds, defined by RFC 4287. inSpecs: - Atom 1.0 - term: application/feed+json definition: >- MIME type recommended by JSON Feed 1.1 for JSON Feed documents. application/json is acceptable as a fallback. inSpecs: - JSON Feed 1.1 - term: text/x-opml definition: >- De facto MIME type used for OPML 2.0 subscription lists in HTTP responses and HTML autodiscovery link elements. inSpecs:

vocabulary: name: RSS Family Vocabulary description: >- Normative and de facto vocabulary covering the RSS family of content syndication standards — RSS 2.0, Atom 1.0 (RFC 4287), JSON Feed 1.1, OPML 2.0, the RSS Best Practices Profile, and HTML feed autodiscovery. Terms are grouped by concept area: feed-level, item-level, identity, dates, enclosures and media, subscription, and discovery. Each term notes which spec(s) it appears in and its closest schema.org analogue when one exists. version: '1.0' created: '2026-05-23' modified: '2026-05-23' feed-level-concepts: - term: Feed definition: >- A document representing a stream of frequently updated content. In RSS 2.0 the feed is the element; in Atom 1.0 it is atom:feed; in JSON Feed 1.1 it is the top-level JSON object. inSpecs: - RSS 2.0 - Atom 1.0 - JSON Feed 1.1 schemaOrg: DataFeed related: - Channel - Item - Entry - term: Channel definition: >- The RSS 2.0 container element that holds feed metadata (title, link, description) and a sequence of elements. The XML root always wraps exactly one channel. inSpecs: - RSS 2.0 schemaOrg: DataFeed related: - Feed - Item - term: Title definition: >- Required human-readable name of the feed (or item). Mandatory in RSS 2.0 , Atom atom:feed, and JSON Feed top-level. In Atom, may carry type='text', 'html', or 'xhtml'. inSpecs: - RSS 2.0 - Atom 1.0 - JSON Feed 1.1 schemaOrg: name required: true - term: Description definition: >- Phrase or sentence describing the feed (RSS 2.0 channel) or item. Mandatory at channel level in RSS 2.0; optional in Atom (as subtitle) and JSON Feed (as description). inSpecs: - RSS 2.0 schemaOrg: description - term: Link definition: >- URL associated with a feed or item. In RSS 2.0 it is the website URL and item permalink; in Atom it is structured atom:link with rel attributes (self, alternate, related, enclosure, via, hub). inSpecs: - RSS 2.0 - Atom 1.0 schemaOrg: url related: - PermaLink - Self Link - Hub item-level-concepts: - term: Item definition: >- The RSS 2.0 unit of syndicated content inside a channel. All sub-elements are optional but at least one of or <description> MUST be present. inSpecs: - RSS 2.0 schemaOrg: Article related: - Entry - Channel - GUID - term: Entry definition: >- The Atom 1.0 unit of syndicated content inside a feed. Each atom:entry MUST have id, title, and updated; author may be inherited from the parent feed; either content or an alternate link is required. inSpecs: - Atom 1.0 schemaOrg: Article required: - id - title - updated - term: Content definition: >- The body of an item or entry. In Atom, atom:content may be text, html, xhtml, or reference remote content via src. In JSON Feed, an item MUST supply at least one of content_html or content_text. inSpecs: - Atom 1.0 - JSON Feed 1.1 schemaOrg: articleBody - term: Summary definition: >- Short representation of an entry's content. Required in Atom when atom:content is base64-encoded, references remote content, or is absent in favor of a link. inSpecs: - Atom 1.0 - JSON Feed 1.1 schemaOrg: abstract identity: - term: GUID definition: >- Globally unique identifier for an RSS 2.0 item. When isPermaLink='true' (default) the value MUST be a resolvable URL. Best practice per the RSS Best Practices Profile is to provide a stable opaque identifier and set isPermaLink='false', commonly using the Tag URI scheme (RFC 4151). inSpecs: - RSS 2.0 - RSS Best Practices Profile schemaOrg: identifier aliases: - Globally Unique Identifier related: - Tag URI - term: ID definition: >- Atom 1.0 atom:id — permanent, universally unique identifier for a feed or entry as an IRI. In JSON Feed, item.id SHOULD be a URL that resolves to the item's permalink. inSpecs: - Atom 1.0 - JSON Feed 1.1 schemaOrg: identifier required: true - term: PermaLink definition: >- Permanent URL for an item or entry. In RSS 2.0 the <link> element of an item serves as the permalink; an item's guid is a permalink when isPermaLink='true'. inSpecs: - RSS 2.0 - Atom 1.0 - JSON Feed 1.1 schemaOrg: url - term: Tag URI definition: >- An identifier scheme (RFC 4151) of the form 'tag:authority,YYYY-MM-DD:specific-string' often used as a stable non-URL guid for RSS items to avoid coupling identity to URL changes. inSpecs: - RSS Best Practices Profile related: - GUID dates: - term: pubDate definition: >- Publication date of an RSS 2.0 channel or item, formatted per RFC 822. Aggregators do not honor future-dated pubDate — items SHOULD NOT be published with a future pubDate to attempt embargo. inSpecs: - RSS 2.0 - RSS Best Practices Profile schemaOrg: datePublished - term: lastBuildDate definition: >- RSS 2.0 channel-level RFC 822 timestamp of the last time the channel's content changed. inSpecs: - RSS 2.0 schemaOrg: dateModified - term: updated definition: >- Atom 1.0 atom:updated — most recent instant when the feed or entry was meaningfully modified, as an RFC 3339 timestamp. inSpecs: - Atom 1.0 schemaOrg: dateModified required: true - term: published definition: >- Atom 1.0 atom:published — initial creation or first availability of an entry, as an RFC 3339 timestamp. inSpecs: - Atom 1.0 schemaOrg: datePublished - term: date_published definition: >- JSON Feed 1.1 RFC 3339 timestamp of an item's original publication. inSpecs: - JSON Feed 1.1 schemaOrg: datePublished - term: date_modified definition: >- JSON Feed 1.1 RFC 3339 timestamp of an item's last modification. inSpecs: - JSON Feed 1.1 schemaOrg: dateModified enclosures-and-media: - term: Enclosure definition: >- An RSS 2.0 media attachment on an item, with url, length (bytes), and type (MIME) attributes. The foundation of podcasting. Best practice is no more than one enclosure per item because not all aggregators handle multiple enclosures. inSpecs: - RSS 2.0 - RSS Best Practices Profile schemaOrg: associatedMedia related: - Attachment - Media RSS - term: Attachment definition: >- JSON Feed 1.1 item-level media attachment with url, mime_type, optional title, size_in_bytes, and duration_in_seconds. inSpecs: - JSON Feed 1.1 schemaOrg: associatedMedia - term: Media RSS definition: >- A widely-used XML namespace extension to RSS 2.0 (http://search.yahoo.com/mrss/) for richer media metadata than the single-enclosure model — multiple media:content nodes, thumbnails, ratings, credits. inSpecs: - Media RSS (extension) related: - Enclosure subscription: - term: OPML definition: >- Outline Processor Markup Language — an XML format whose most common application is exchanging lists of RSS/Atom/JSON Feed subscriptions between feed readers. Subscription-list outlines use type='rss' with xmlUrl pointing to the feed and htmlUrl pointing to the site. inSpecs: - OPML 2.0 aliases: - Outline Processor Markup Language - term: Subscription List definition: >- An OPML 2.0 document whose body contains outline elements representing a user's feed subscriptions, optionally nested into folder outlines. The de facto portable format for feed-reader import/export. inSpecs: - OPML 2.0 related: - OPML - Outline - term: Outline definition: >- The fundamental OPML element; for subscription lists, a leaf outline represents one feed subscription via type='rss', text, title, xmlUrl, and htmlUrl. inSpecs: - OPML 2.0 discovery: - term: Autodiscovery definition: >- HTML convention by which a web page advertises its feed(s) via <link rel='alternate' type='application/rss+xml' href='...'> elements in the document head. Feed readers, browsers, and crawlers use this to locate feeds from a homepage URL alone. The same pattern is used with application/atom+xml and application/feed+json. inSpecs: - HTML - RSS Best Practices Profile related: - Self Link - .well-known/feeds - term: Self Link definition: >- An atom:link with rel='self' pointing at the feed's own canonical URL. Required for proper feed identity and relocation across the Atom ecosystem; widely adopted in RSS 2.0 via the Atom namespace as well. inSpecs: - Atom 1.0 related: - feed_url - term: feed_url definition: >- JSON Feed 1.1 top-level URL identifying the feed itself; the JSON Feed equivalent of atom:link rel='self'. Strongly recommended for public feeds because it enables relocation. inSpecs: - JSON Feed 1.1 - term: home_page_url definition: >- JSON Feed 1.1 top-level URL identifying the human-readable website the feed describes — the equivalent of RSS 2.0 channel <link>. inSpecs: - JSON Feed 1.1 push-and-real-time: - term: WebSub definition: >- W3C Recommendation (formerly PubSubHubbub) defining a publish/subscribe protocol over HTTP that turns pull-based feeds into push-based ones. JSON Feed 1.1 surfaces WebSub hubs via the top-level 'hubs' array; Atom and RSS surface them via <link rel='hub' href='...'> elements. inSpecs: - WebSub (W3C) - JSON Feed 1.1 - Atom 1.0 - RSS 2.0 related: - Hub - term: Hub definition: >- A WebSub hub URL advertised by a feed to which subscribers can subscribe to receive real-time notifications when the feed changes, avoiding pure polling. inSpecs: - WebSub - JSON Feed 1.1 related: - WebSub - term: rssCloud definition: >- The original RSS 2.0 <cloud> element predating WebSub, declaring a service that aggregators can register with to be notified of channel updates. Limited adoption today. inSpecs: - RSS 2.0 extensions: - term: XML Namespace Extension definition: >- The standard mechanism for extending RSS 2.0 and Atom feeds without changing the core spec — declare a new XML namespace and add elements from that namespace alongside core ones. RSS 2.0's frozen status makes namespaces the only path for new features. inSpecs: - RSS 2.0 - Atom 1.0 related: - Media RSS - iTunes Podcast Namespace - Dublin Core - term: iTunes Podcast Namespace definition: >- Apple's RSS 2.0 namespace extension (http://www.itunes.com/dtds/podcast-1.0.dtd) defining the de facto podcast metadata vocabulary — itunes:author, itunes:category, itunes:explicit, itunes:image, itunes:duration, itunes:summary. inSpecs: - iTunes Podcast Namespace (extension) - term: Dublin Core definition: >- A widely-used metadata namespace (http://purl.org/dc/elements/1.1/) embedded in many RSS 2.0 feeds for canonical metadata like dc:creator and dc:date. inSpecs: - Dublin Core - RSS 2.0 (via extension) media-types: - term: application/rss+xml definition: >- IANA-registered MIME type for RSS 2.0 feeds. Used as the value of the type attribute in autodiscovery <link> elements and as the Content-Type response header when serving RSS feeds. inSpecs: - RSS 2.0 - term: application/atom+xml definition: >- IANA-registered MIME type for Atom 1.0 feeds, defined by RFC 4287. inSpecs: - Atom 1.0 - term: application/feed+json definition: >- MIME type recommended by JSON Feed 1.1 for JSON Feed documents. application/json is acceptable as a fallback. inSpecs: - JSON Feed 1.1 - term: text/x-opml definition: >- De facto MIME type used for OPML 2.0 subscription lists in HTTP responses and HTML autodiscovery link elements. inSpecs: - OPML 2.0