#   rfc7991bis.rnc
#
#   RFCXML v3 RNC schema. Includes changes made after the publication of RFC 
#   7991 and features deprecated in RFC 7991.
#
#   To use in an RFCXML I-D add the following line before the <rfc> element:
#        <?xml-model href="rfc7991bis.rnc"?>
#
#   Documentation is at https://authors.ietf.org/en/templates-and-schemas

namespace a = "http://relaxng.org/ns/compatibility/annotations/1.0"

rfc =
 element rfc {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute number { text }?,
   [ a:defaultValue = "" ] attribute obsoletes { text }?,
   [ a:defaultValue = "" ] attribute updates { text }?,
   attribute category { 
     "std" | "bcp" | "exp" | "info" | "historic" 
   }?,
   attribute mode { text }?,
   [ a:defaultValue = "false" ]
   attribute consensus { "no" | "yes" | "false" | "true" }?,
   attribute seriesNo { text }?,
   attribute ipr { text }?,
   attribute iprExtract { xsd:IDREF }?,
   [ a:defaultValue = "IETF" ]
   attribute submissionType {
     "IETF" | "IAB" | "IRTF" | "independent"
   }?,
   attribute docName { text }?,
   [ a:defaultValue = "false" ]
   attribute sortRefs { "true" | "false" }?,
   [ a:defaultValue = "true" ]
   attribute symRefs { "true" | "false" }?,
   [ a:defaultValue = "true" ]
   attribute tocInclude { "true" | "false" }?,
   [ a:defaultValue = "3" ] attribute tocDepth { text }?,
   attribute prepTime { text }?,
   [ a:defaultValue = "true" ]
   attribute indexInclude { "true" | "false" }?,
   attribute version { text }?,
   [ a:defaultValue = "Common,Latin" ] attribute scripts { text }?,
   attribute expiresDate { text }?,
   link*,
   front,
   middle,
   back?
 }

link =
 element link {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute href { text },
   attribute rel { text }?
 }

front =
 element front {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   title,
   seriesInfo*,
   author+,
   date?,
   area*,
   workgroup*,
   keyword*,
   abstract?,
   note*,
   boilerplate?,
   toc?
 }

title =
 element title {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute abbrev { text }?,
   attribute ascii { text }?,
   (text | br)*
 }

author =
 element author {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute initials { text }?,
   attribute asciiInitials { text }?,
   attribute surname { text }?,
   attribute asciiSurname { text }?,
   attribute fullname { text }?,
   attribute role { "editor" }?,
   attribute asciiFullname { text }?,
   organization?,
   address?
 }

contact =
 element contact {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute initials { text }?,
   attribute asciiInitials { text }?,
   attribute surname { text }?,
   attribute asciiSurname { text }?,
   attribute fullname { text }?,
   attribute asciiFullname { text }?,
   organization?,
   address?
 }

organization =
 element organization {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute abbrev { text }?,
   attribute ascii { text }?,
   attribute asciiAbbrev { text }?,
   [ a:defaultValue = "true" ]
   attribute showOnFrontPage { "true" | "false" }?,
   text
 }

address =
 element address {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   postal?,
   phone?,
   facsimile?,
   email*,
   uri?
 }

postal =
 element postal {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (( city | cityarea | code | country | extaddr | pobox | region
      | sortingcode | street)* 
    | postalLine+)
 }

extaddr =
 element extaddr {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

pobox =
 element pobox {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

street =
 element street {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

cityarea =
 element cityarea {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

city =
 element city {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

region =
 element region {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

code =
 element code {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

sortingcode =
 element sortingcode {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

country =
 element country {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

postalLine =
 element postalLine {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

phone =
 element phone {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   text
 }

facsimile =
 element facsimile {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   text
 }

email =
 element email {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute ascii { text }?,
   text
 }

uri =
 element uri {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   text
 }

date =
 element date {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute day { text }?,
   attribute month { text }?,
   attribute year { text }?,
   text
 }

area =
 element area {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   text
 }

workgroup =
 element workgroup {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   text
 }

keyword =
 element keyword {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   text
 }

abstract =
 element abstract {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   (dl | ol | t | ul)+
 }

note =
 element note {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute title { text }?,
   attribute pn { xsd:ID }?,
   [ a:defaultValue = "false" ]
   attribute removeInRFC { "true" | "false" }?,
   name?,
   (dl | ol | t | ul)+
 }

boilerplate =
 element boilerplate {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   section+
 }

toc =
 element toc {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   section*
 }

middle =
 element middle {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   section+
 }

section =
 element section {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   attribute title { text }?,
   [ a:defaultValue = "true" ]
   attribute numbered { "true" | "false" }?,
   [ a:defaultValue = "default" ]
   attribute toc { "include" | "exclude" | "default" }?,
   [ a:defaultValue = "false" ]
   attribute removeInRFC { "true" | "false" }?,
   name?,
   (artset
    | artwork
    | aside
    | author
    | blockquote
    | contact
    | dl
    | figure
    | iref
    | ol
    | sourcecode
    | t
    | table
    | texttable
    | ul)*,
   section*
 }

name =
 element name {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute slugifiedName { xsd:ID }?,
   (text
    | bcp14
    | br
    | cref
    | em
    | eref
    | iref
    | relref
    | strong
    | sub
    | sup
    | tt
    | xref)*
 }

br =
 element br {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   empty
 }

t =
 element t {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   attribute hangText { text }?,
   [ a:defaultValue = "0" ]
   attribute indent { text }?,
   [ a:defaultValue = "false" ]
   attribute keepWithNext { "true" | "false" }?,
   [ a:defaultValue = "false" ]
   attribute keepWithPrevious { "true" | "false" }?,
   (text
    | bcp14
    | br
    | contact
    | cref
    | em
    | eref
    | iref
    | \list
    | relref
    | spanx
    | strong
    | sub
    | sup
    | tt
    | u
    | vspace
    | xref)*
 }

aside =
 element aside {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   (artset
    | artwork
    | blockquote
    | dl
    | figure
    | iref
    | ol
    | t
    | table
    | ul)*

 }

blockquote =
 element blockquote {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   attribute cite { text }?,
   attribute quotedFrom { text }?,
   ((artset | artwork | dl | figure | ol | sourcecode | t | ul)+
    | (text
       | bcp14
       | br
       | cref
       | em
       | eref
       | iref
       | relref
       | strong
       | sub
       | sup
       | tt
       | u
       | xref)+)
 }

\list =
 element list {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   [ a:defaultValue = "empty" ] attribute style { text }?,
   attribute hangIndent { text }?,
   attribute counter { text }?,
   attribute pn { xsd:ID }?,
   t+
 }

ol =
 element ol {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   [ a:defaultValue = "1" ] attribute type { text }?,
   [ a:defaultValue = "1" ] attribute start { text }?,
   attribute group { text }?,
   [ a:defaultValue = "normal" ]
   attribute spacing { "normal" | "compact" }?,
   [ a:defaultValue = "adaptive" ]
   attribute indent { text | "adaptive" }?,
   attribute pn { xsd:ID }?,
   li+
 }

ul =
 element ul {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   [ a:defaultValue = "normal" ]
   attribute spacing { "normal" | "compact" }?,
   ([ a:defaultValue = "false" ]
    attribute empty { "true" | "false" },
    [ a:defaultValue = "false" ]
    attribute bare { "true" | "false" }?)?,
   [ a:defaultValue = "3" ]
    attribute indent { text }?,
    attribute pn { xsd:ID }?,
   li+
 }

li =
 element li {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute derivedCounter { text }?,
   attribute pn { xsd:ID }?,
   (( artset
      | artwork
      | blockquote
      | dl
      | figure
      | ol
      | sourcecode
      | t
      | table
      | ul)+
    | (text
       | bcp14
       | br
       | cref
       | em
       | eref
       | iref
       | relref
       | strong
       | sub
       | sup
       | tt
       | u
       | xref)+)
 }

dl =
 element dl {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   [ a:defaultValue = "normal" ]
   attribute spacing { "normal" | "compact" }?,
   [ a:defaultValue = "false" ]
   attribute newline { "true" | "false" }?,
   [ a:defaultValue = "3" ]
   attribute indent { text }?,
   attribute pn { xsd:ID }?,
   (dt, dd)+
 }

dt =
 element dt {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   (text
    | bcp14
    | br
    | cref
    | em
    | eref
    | iref
    | relref
    | strong
    | sub
    | sup
    | tt
    | xref)*
 }

dd =
 element dd {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   (( artset
      | artwork
      | aside
      | dl
      | figure
      | ol
      | sourcecode
      | t
      | table
      | ul)+
    | (text
       | bcp14
       | br
       | cref
       | em
       | eref
       | iref
       | relref
       | strong
       | sub
       | sup
       | tt
       | u
       | xref)+)
 }

xref =
 element xref {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute target { xsd:IDREF },
   [ a:defaultValue = "false" ]
   attribute pageno { "true" | "false" }?,
   [ a:defaultValue = "default" ]
   attribute format { "default" | "title" | "counter" | "none" }?,
   attribute derivedContent { text }?,
   [ a:defaultValue = "of" ]
   attribute sectionFormat { "of" | "comma" | "parens" | "bare" }?,
   attribute section { text }?,
   attribute relative { text }?,
   attribute derivedLink { text }?,
   (text | em | strong | sub | sup | tt)*
 }

relref =
 element relref {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute target { xsd:IDREF },
   [ a:defaultValue = "of" ]
   attribute displayFormat { "of" | "comma" | "parens" | "bare" }?,
   attribute derivedContent { text }?,
   attribute section { text },
   attribute relative { text }?,
   attribute derivedLink { text }?,
   text
 }

eref =
 element eref {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   [ a:defaultValue = "none" ]
   attribute brackets { "none" | "angle" }?,
   attribute target { text },
   text
 }

iref =
 element iref {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute item { text },
   [ a:defaultValue = "" ] attribute subitem { text }?,
   [ a:defaultValue = "false" ]
   attribute primary { "true" | "false" }?,
   attribute pn { xsd:ID }?,
   empty
 }

cref =
 element cref {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute source { text }?,
   [ a:defaultValue = "true" ]
   attribute display { "true" | "false" }?,
   (text
    | br
    | em
    | eref
    | relref 
    | strong
    | sub
    | sup
    | tt
    | xref)*
 }

tt =
 element tt {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text
    | bcp14
    | br
    | cref
    | em
    | eref
    | iref
    | relref
    | strong
    | sub
    | sup
    | xref)*
 }

strong =
 element strong {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text
    | bcp14
    | br
    | cref
    | em
    | eref
    | iref
    | relref
    | sub
    | sup
    | tt
    | xref)*
 }

em =
 element em {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text
    | bcp14
    | br
    | cref
    | eref
    | iref
    | relref
    | strong
    | sub
    | sup
    | tt
    | xref)*
 }

sub =
 element sub {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text
    | bcp14
    | cref
    | em
    | eref
    | iref
    | relref
    | strong
    | sub
    | sup
    | tt
    | xref)*
 }

sup =
 element sup {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text
    | bcp14
    | cref
    | em
    | eref
    | iref
    | relref
    | strong
    | sub
    | sup
    | tt
    | xref)*
 }

spanx =
 element spanx {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   [ a:defaultValue = "preserve" ]
   attribute xml:space { "default" | "preserve" }?,
   [ a:defaultValue = "emph" ] attribute style { text }?,
   text
 }

vspace =
 element vspace {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   [ a:defaultValue = "0" ] attribute blankLines { text }?,
   empty
 }

figure =
 element figure {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   [ a:defaultValue = "" ] attribute title { text }?,
   [ a:defaultValue = "false" ]
   attribute suppress-title { "true" | "false" }?,
   attribute src { text }?,
   attribute originalSrc { text }?,
   [ a:defaultValue = "left" ]
   attribute align { "left" | "center" | "right" }?,
   [ a:defaultValue = "" ] attribute alt { text }?,
   [ a:defaultValue = "" ] attribute width { text }?,
   [ a:defaultValue = "" ] attribute height { text }?,
   name?,
   iref*,
   preamble?,
   (artset | artwork | sourcecode)+,
   postamble?
 }

table =
 element table {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   [ a:defaultValue = "center" ]
   attribute align { "left" | "center" | "right" }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   name?,
   iref*,
   thead?,
   tbody+,
   tfoot?
 }

preamble =
 element preamble {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text
    | bcp14
    | cref
    | em
    | eref
    | iref
    | relref
    | spanx
    | strong
    | sub
    | sup
    | tt
    | u
    | xref)*
 }

artset =
 element artset {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   artwork+
 }


artwork =
 element artwork {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   attribute xml:space { text }?,
   [ a:defaultValue = "" ] attribute name { text }?,
   [ a:defaultValue = "" ] attribute type { text }?,
   attribute src { text }?,
   [ a:defaultValue = "left" ]
   attribute align { "left" | "center" | "right" }?,
   [ a:defaultValue = "" ] attribute alt { text }?,
   [ a:defaultValue = "" ] attribute width { text }?,
   [ a:defaultValue = "" ] attribute height { text }?,
   attribute originalSrc { text }?,
   (text* | svg)
 }
include "SVG-1.2-RFC.rnc"

sourcecode =
 element sourcecode {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   attribute pn { xsd:ID }?,
   [ a:defaultValue = "" ] attribute name { text }?,
   [ a:defaultValue = "" ] attribute type { text }?,
   [ a:defaultValue = "false" ] 
   attribute markers { "true" | "false" }?,
   attribute src { text }?,
   attribute originalSrc { text }?,
   text
 }

thead =
 element thead {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   tr+
 }

tbody =
 element tbody {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   tr+
 }

tfoot =
 element tfoot {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   tr+
 }

tr =
 element tr {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   (td | th)+
 }

td =
 element td {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   [ a:defaultValue = "1" ] attribute colspan { text }?,
   [ a:defaultValue = "1" ] attribute rowspan { text }?,
   [ a:defaultValue = "left" ]
   attribute align { "left" | "center" | "right" }?,
   ((artset | artwork | dl | figure | ol | sourcecode | t | ul)+
    | (text
       | bcp14
       | br
       | cref
       | em
       | eref
       | iref
       | relref
       | strong
       | sub
       | sup
       | tt
       | u
       | xref)*)
 }

th =
 element th {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   [ a:defaultValue = "1" ] attribute colspan { text }?,
   [ a:defaultValue = "1" ] attribute rowspan { text }?,
   [ a:defaultValue = "left" ]
   attribute align { "left" | "center" | "right" }?,
   ((artset | artwork | dl | figure | ol | sourcecode | t | ul)+
    | (text
       | bcp14
       | br
       | cref
       | em
       | eref
       | iref
       | relref
       | strong
       | sub
       | sup
       | tt
       | u
       | xref)*)
 }

postamble =
 element postamble {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text | cref | eref | iref | spanx | xref)*
 }

texttable =
 element texttable {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID }?,
   [ a:defaultValue = "" ] attribute title { text }?,
   [ a:defaultValue = "false" ]
   attribute suppress-title { "true" | "false" }?,
   [ a:defaultValue = "center" ]
   attribute align { "left" | "center" | "right" }?,
   [ a:defaultValue = "full" ]
   attribute style { "all" | "none" | "headers" | "full" }?,
   name?,
   preamble?,
   ttcol+,
   c*,
   postamble?
 }

ttcol =
 element ttcol {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute width { text }?,
   [ a:defaultValue = "left" ]
   attribute align { "left" | "center" | "right" }?,
   (cref | eref | iref | xref | text)*
 }

c =
 element c {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text | cref | eref | iref | spanx | xref)*
 }

bcp14 =
 element bcp14 {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   text
 }

back =
 element back {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   displayreference*,
   references*,
   section*
 }

displayreference =
 element displayreference {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute target { xsd:IDREF },
   attribute to { text }
 }

references =
 element references {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute pn { xsd:ID }?,
   attribute anchor { xsd:ID }?,
   attribute title { text }?,
   name?,
   (references+ | (reference | referencegroup)*)
 }

reference =
 element reference {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID },
   attribute derivedAnchor { text }?,
   attribute target { text }?,
   [ a:defaultValue = "true" ]
   attribute quoteTitle { "true" | "false" }?,
   attribute quote-title { "true" | "false" }?,
   stream?,
   front,
   (annotation | format | refcontent | seriesInfo)*
 }

stream = 
 element stream {
   ( "IETF" | "IAB" | "IRTF" | "independent" )?
}

referencegroup =
 element referencegroup {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute anchor { xsd:ID },
   attribute derivedAnchor { text }?,
   attribute target { text }?,
   reference+
 }

seriesInfo =
 element seriesInfo {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute name { text },
   attribute value { text },
   attribute asciiName { text }?,
   attribute asciiValue { text }?,
   attribute status { text }?,
   attribute stream { "IETF" | "IAB" | "IRTF" | "independent" }?,
   empty
 }

format =
 element format {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   attribute target { text }?,
   attribute type { text },
   attribute octets { text }?,
   empty
 }

annotation =
 element annotation {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text
    | bcp14
    | cref
    | em
    | eref
    | iref
    | relref
    | spanx
    | strong
    | sub
    | sup
    | tt
    | u
    | xref)*
 }

refcontent =
 element refcontent {
   attribute xml:base { text }?,
   attribute xml:lang { text }?,
   (text | bcp14 | em | strong | sub | sup | tt)*
 }

u = 
 element u {
   attribute anchor { xsd:ID }?,
   attribute ascii { text }?,
   [ a:defaultValue = "lit-name-num" ]
   attribute format { text }?,
   attribute pn { xsd:ID }?,
   text
 }

start |= rfc