RFC2629 through XSLTJ. Reschke
greenbytes
July 2016

Transforming RFC2629-formatted XML through XSLT



1. Introduction

This document describes a set of XSLT transformations that can be used to transform "XML2RFC" XML ([RFC7749], updating [RFC2629]) to various output formats, such as HTML and PDF. The main topics are

The full distribution is available at <http://greenbytes.de/tech/webdav/rfc2629xslt.zip>.


2. Supported RFC2629 elements

rfc2629.xslt supports both all RFC2629 grammar elements and the extensions implemented in xml2rfc 1.36.

2.1 Extension elements

rfc2629.xslt supports two kind of extension elements, using different XML namespaces.

The first set contains (hopefully) generally useful extensions, see Section 11.

The second set is used for change and issue tracking and currently is not documented here. Please email the author in case you're interested in using these extensions.


3. Processing Instructions

All PIs can be set as XSLT parameter as well, overriding any value that is found in the source file to be transformed.

Using processing instructions:

<?rfc toc="yes"?>
<?rfc-ext support-rfc2731="no"?>

Using XSLT parameters (Saxon):

java -cp saxon.jar com.icl.saxon.StyleSheet source.xml rfc2629.xslt \
  xml2rfc-toc=yes xml2rfc-ext-support-rfc2731=no > result.html 

Using XSLT parameters (xsltproc):

xsltproc --param xml2rfc-toc '"yes"' \
   --param xml2rfc-ext-support-rfc2731 '"no"' \
   rfc2629.xslt source.xml > result.html 

(note the required quoting of string parameters)

3.1 Supported xml2rfc-compatible PIs

PI targetPI pseudo-attributeXSLT parameter namedefaultcomment
rfcbackground
xml2rfc-background
(not set)
rfccompact
xml2rfc-compact
"no"only applies to HTML output method when printing
rfccomments
xml2rfc-comments
(not set)
rfcdocmapping
"yes"This is the default for rfc2629.xslt anyway, and it can not be changed
rfcediting
xml2rfc-editing
"no"
rfcfooter
xml2rfc-footer
(not set)
rfcheader
xml2rfc-header
(not set)
rfcinclude
only partly supported, use external entities instead (see Appendix C.1) or other tools (Section 13.8) instead
rfcinline
xml2rfc-inline
(not set)
rfciprnotified
xml2rfc-iprnotified
"no"
rfclinkmailto
xml2rfc-linkmailto
"yes"
rfcprivate
xml2rfc-private
(not set)
rfcrefparent
xml2rfc-private
"References"Title for References sections when automatically inserted
rfcrfcedstyle
xml2rfc-rfcedstyle
(not set)(limited support)
rfcsortrefs
xml2rfc-sortrefs
"no"
rfcsymrefs
xml2rfc-symrefs
"yes"The default has changed from "no" to "yes" as of June 6, 2007 and xml2rfc 1.33pre4.
rfctoc
xml2rfc-toc
"no"
rfctocdepth
xml2rfc-tocdepth
99
rfctopblock
xml2rfc-topblock
"yes"

3.2 Unsupported xml2rfc-compatible PIs

PI targetPI pseudo-attributecomment
rfcneedLines
rfcslides
rfcstrict
rfcsubcompact
rfctocindent
(defaults to "yes")
rfctocompact

3.3 Extension PIs

PI targetPI pseudo-attributeXSLT parameter namedefaultdescription
rfc-extallow-markup-in-artwork
xml2rfc-allow-markup-in-artwork
"no"Enables support for specific elements inside abstract elements (using this extension makes the document incompatible to the RFC2629bis DTD; see description of conversion XSLT in Section 13.4).
rfc-extauthors-section
xml2rfc-ext-authors-section
"end"When "before-appendices", place the authors section between references and appendices (this ordering was used a long time ago).
rfc-extduplex
xml2rfc-ext-duplex
"no"When set to "yes", format the PDF output for doublesided printing.
rfc-exthtml-pretty-print
xml2rfc-ext-html-pretty-print
Used to specify a JS-based code pretty-printer; the value is the CSS class name to insert, followed by a blank space, followed by the URI of the JS library. For instance: "prettyprint https://cdn.rawgit.com/google/code-prettify/master/loader/run_prettify.js"
rfc-extinclude-index
xml2rfc-ext-include-index
"yes"When set to "no", no index will be generated.
rfc-extinclude-references-in-index
xml2rfc-ext-include-references-in-index
"no"When set to "yes", index entries are generated for all references.
rfc-extinsert-metadata
xml2rfc-ext-insert-metadata
"yes"When set to "yes", include JS code that fetches current RFC metadata and inserts it into the front page (standards track, obsoletion, updates, errata).
rfc-extjustification
xml2rfc-ext-justification
"never""never": never emit justified text, "always": always emit justified text, "print": only emit justified text for print media.
rfc-extparse-xml-in-artwork
xml2rfc-parse-xml-in-artwork
"no"May be used to enable parsing of XML content in figures (MSXML only).
rfc-extsec-no-trailing-dots
xml2rfc-ext-sec-no-trailing-dots
When set to "yes", add trailing dots to section numbers. This seems to be the preferred format in the newest RFCs.
rfc-extsupport-rfc2731
xml2rfc-ext-support-rfc2731
"yes"Decides whether the HTML transformation should generate META tags according Section 6.4.

4. Anchors

The transformation automatically generates anchors that are supposed to be stable and predictable and that can be used to identify specific parts of the document. Anchors are generated both in HTML and XSL-FO content (but the latter will only be used for PDF output when the XSL-FO engine supports producing PDF anchors).

The following anchors get auto-generated:

Anchor nameDescription
rfc.abstract
Abstract
rfc.authors
Authors section
rfc.copyright
Copyright section
rfc.copyrightnotice
Copyright notice
rfc.figure.n
Figures (titled)
rfc.figure.u.n
Figures (untitled)
rfc.index
Index
rfc.ipr
Intellectual Property
rfc.iref.n
Internal references
rfc.note.n
Notes (from front section)
rfc.references
References
rfc.references.n
Additional references
rfc.section.n
Section n
rfc.section.n.p.m
Section n, paragraph m
rfc.status
Status of memo
rfc.table.n
Tables (titled)
rfc.table.u.n
Tables (untitled)
rfc.toc
Table of contents
rfc.xref.name.n
References to reference n to name

5. Supported XSLT engines

The transformation requires a non-standard extension function (see exsl:node-set) which is however widely available. XSLT processors that do not support this extension (or a functional equivalent, such as msxsl:node-set) currently are not supported.

Input documents do not always specify the date completely. In this case, the transformation attempts to let the XSLT engine to compute the system date, using either scripting in Microsoft's XSLT engine, or the exsl:date-time extension function.

5.1 Standalone Engines

The following XSLT engines are believed to work well:

5.2 In-Browser Engines

The following browsers seem to work fine:

The following browsers are known not to work properly:

  • Firefox 1.*/2.*: (missing extension function - see change request at Mozilla BugZilla 193678)

  • Opera 9.21: execution fails, potentially to a somewhat complex XPath expression (reported to Opera as bug 245725).

  • Opera 9.5 and 9.6: transformation appears to work, but CSS isn't getting applied (reported to Opera as bug 337388 on 2008-06-12).

  • Safari 2.* supports client-side XSLT as of MacOS X 10.4, but misses required extension functions. A problem with stylesheets producing non-ASCII output (such as NBSP characters) has been fixed as of OSX 10.4.4. Both problems have been reported through Apple's bug tracking system, see <http://drakken.dbc.mtview.ca.us/pipermail/xml2rfc/2005-May/002073.html> and <http://bugs.webkit.org/show_bug.cgi?id=4079>.


6. Transforming to HTML

Transformation to HTML can be done inside the browser if it supports XSLT. To enable this, add the following processing instruction to the start of the source file:

  <?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>

(and ensure that rfc2629.xslt is present).

6.1 HTML compliance

The transformation result is supposed to conform to HTML5 [HTML5]. This can be checked using the W3C's online validator at <http://validator.w3.org>.

XSLT 1.0 is not capable to directly emit the HTML doctype declaration, thus uses the SYSTEM ID "about:legacy-compat" instead (see Section 8.1.1 of [HTML5]).

When not run in a browser, the doctype declaration can be adjusted using a small script, such as with:

saxon test.xml rfc2629.xslt | awk -f html5doctype.awk

with

#!/usr/bin/awk -f

# waitfordoctype:
# 0: wait for line starting with DOCTYPE and eat empty lines
# 1: wait for line starting with <html
# 2: afterwards

BEGIN {
  waitfordoctype = 0;
}

/<!DOCTYPE .*/ {
  if (waitfordoctype == 0) {
    waitfordoctype = 1
  }
}

/<html.*/ {
  if (waitfordoctype == 1) {
    waitfordoctype = 2
    printf("<!DOCTYPE html>\n")
  }
  else {
    print
  }
}

{
  if (waitfordoctype == 0 && $0 != "") {
    print
  }
  else if (waitfordoctype == 2) {
    print
  }
}

6.3 Standard HTML metadata

The following standard HTML META elements are produced:

META namedescription
generator
from XSLT engine version and stylesheet version
keywords
from keyword elements in front section

6.4 Dublin Core (RFC2731) metadata

Unless turned off using the "rfc-ext support-rfc2731" processing instruction, the transformation will generate metadata according to [RFC2731] and [DC-HTML].

The following DCMI properties are produced:

META namedescription
DC.Creator
from author information in front section
DC.Date.Issued
from date information in front section
DC.Description.Abstract
from abstract
DC.Identifier
document URN [RFC2648] from "docName" attribute
DC.isPartOf
RFC ISSN (for RFCs)
DC.Relation.Replaces
from "obsoletes" attribute

7. Transforming to XHTML

Transforming to XHTML requires slightly different XSLT output options and is implemented by the derived transformation script rfc2629toXHTML.xslt.


8. Transforming to CHM (Microsoft Compiled Help)

To generate a CHM file using Microsoft's HTML Help Compiler (hhc), three files are required in addition to the HTML file.

  1. hhc - table of contents file (HTML)
  2. hhk - index file (HTML)
  3. hhp - project file (plain text)

The three files are generated with three specific transformations, each requiring the additional XSLT parameter "basename" to specify the filename prefix.

Example:

saxon rfc2616.xml rfc2629toHhp.xslt basename=rfc2616  > rfc2616.hhp
saxon rfc2616.xml rfc2629toHhc.xslt basename=rfc2616  > rfc2616.hhc
saxon rfc2616.xml rfc2629toHhk.xslt basename=rfc2616  > rfc2616.hhk
hhc rfc2616.hhp

9. Transforming to PDF

9.1 Via XSL-FO

Transformation to XSL-FO [XSL-FO] format is available through rfc2629toFO.xslt (which includes rfc2629.xslt, so keep both in the same folder).

Compared to HTML user agents, XSL-FO engines unfortunately either come as open source (for instance, Apache FOP) or feature-complete (for instance, AntennaHouse XSL Formatter), but not both at the same time.

As Apache FOP needs special workarounds (index generation), and some popular extensions aren't standardized yet, the translation produces a generic output (hopefully) conforming to [XSL-FO]. Specific backends (xsl11toFop.xslt, xsl11toXep.xslt, xsl11toAn.xslt) then provide post-processing for the individual processors.

9.1.1 Example: producing output for Apache FOP

Example:

saxon rfc2616.xml rfc2629toFo.xslt > tmp.fo
saxon tmp.fo xsl11toFop.xslt > rfc2629.fo

9.2 Via HTML

PDF output can also be produced directly from (X)HTML. One simple approach is to rely on the browser's printing function, and to use a printer driver that produces PDF. Depending on the brower's CSS capabilities, the output will behave properly with respect to table breaks etc.

An alternative is PrinceXML (see <http://www.princexml.com/>), which can produce PDF directly from (X)HTML input, based on the CSS printing information.

For instance, PDF output with text justification turned on can be produced with:

saxon input.xml rfc2629.xslt > output.html
prince output.html output.pdf

10. Transforming to ePub

Experimental transformation to ePub format is available through a set of stylesheets, and the Unix Shell script mkepub.sh (which requires that "zip" and either "saxon" or "xsltproc" are installed).

For instance, an epub version of rfc2616.xml can be generated like this:

mkepub.sh rfc2616.xml

11. Generic Extensions

This section documents extensions implemented in rfc2629.xslt, using the extension namespace "http://purl.org/net/xml2rfc/ext".

11.1 <abnf-char-sequence> element

Converts the contained quoted string into a hex-encoded character sequence, for use in case-sensitive ABNF productions.

For instance, "<x:abnf-char-sequence>"HTTP"</x:abnf-char-sequence>" gets converted to "%x48.54.54.50".

11.2 <anchor-alias> element

Using its "value" attribute, this element allows the definition of an internal link target alias for the enclosing element. This alias can then be used with the <ref> element for intra-document references.

Note that the anchor alias is not subject to the naming constraints that apply to anchor elements (which are XML names).

11.3 <bcp14> element

This element marks the content as being one of the normative keywords defined in [RFC2119].

The DOCTYPE definition below allows using these keywords using XML entity expansion: such as in "...server &MUST; accept...".

<!DOCTYPE rfc [
 <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >MAY</bcp14>">
 <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >MUST</bcp14>">
 <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >MUST NOT</bcp14>">
 <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >OPTIONAL</bcp14>">
 <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >RECOMMENDED</bcp14>">
 <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >REQUIRED</bcp14>">
 <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >SHALL</bcp14>">
 <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >SHALL NOT</bcp14>">
 <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >SHOULD</bcp14>">
 <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'
   >SHOULD NOT</bcp14>">]>

11.4 <bb> element

Marking up a string as <bb> indicates that it represents the bottom line of a box drawing, replacing the "+" and "-" characters accordingly.

11.5 <bc> element

Marking up a string as <bc> indicates that it represents a center line of a box drawing, replacing the "|" character accordingly.

11.6 <blockquote> element

This element is like the <blockquote> element defined in Section 4.4.4 of [HTML5] (note this is a block-level element!). It should contain one or more <t> child elements.

11.7 <bt> element

Marking up a string as <bt> indicates that it represents the top line of a box drawing, replacing the "+" and "-" characters accordingly.

11.8 <dfn> element

This element is like the <dfn> element defined in Section 4.5.8 of [HTML5].

11.9 <feedback> element

This elements allows declaring a feedback link for document reviewers. The template string takes the form of a URI template, such as:

<x:feedback template="mailto:ietf-http-wg@w3.org?subject={docname},%20%22{section}%22&amp;body=&lt;{ref}&gt;:"/>

where "docname" is substituted by the document name, "section" is substituted by section title (number and name), and "ref" is substituted by a URI pointing to the section being referenced.

11.10 <h> element

This element is like the "h" element in [XHTML2].

11.11 <highlight> element

Used to highlight text passages, currently only allowed in <artwork>.

Note: this is stripped when generating input for xml2rfc, so please use with care.

11.12 <length-of> element

This element can be used to insert the length of another formatted section (in decimal).

Example: computing the Content-Length header value

<artwork>
...
Content-Length: <x:length-of target="req"/>
  
<x:span anchor="req">123456789
<x:span><artwork/>

The lenght computation counts line ends as two characters (CRLF).

Note that indentation characters in artwork will be counted. The "indented" attribute allows to specify the amount of indentation to be substracted from the computed length.

11.14 <lt> element

Used for grouping multiple <t> elements into a single list item.

11.15 <note> element

Can be used to add a note, usually indented by a few characters. It should contain one or more <t> child elements.

11.16 <parse-xml> element

This element instructs the processor to parse the contents as XML and to warn when there's a problem (requires either MSXML or Saxon8 or newer).

11.17 <prose> element

This element can be used inside <reference> to add plain text (before the date, when present).

See also <refcontent> (Section 12.16).

11.18 <q> element

This element is like the <q> element defined in Section 4.5.7 of [HTML5].

11.19 <ref> element

This element is a simplified variant of the <xref> element, in that no "target" attribute needs to be specified, instead the text contents acts as identifier. That in itself wouldn't be terribly useful, but together with the <anchor-alias>, it allows referring to other parts of the document with minimal additional markup.

For instance, given an alias definition such as

<section title="Test" anchor="test">
  <x:anchor-alias value="alias1"/>
  <x:anchor-alias value="alias 2"/>
  ...
</section>

the following simple references

<x:ref>test</x:ref>
<x:ref>alias1</x:ref>
<x:ref>alias 2</x:ref>

are equivalent to...:

<xref target="test">test</xref>
<xref target="test">alias1</xref>
<xref target="test">alias 2</xref>

11.20 <source> element

Can be used to enhance a <reference> with information about the location for the XML source. This can be used by the <xref> processing code to automatically extract the target section number.

For example:

...
<xref target="RFC2616" x:fmt="of" x:rel="#PUT" />
...

<reference target="RFC2616"/>
  ...
  <x:source href="rfc2616.xml"/>
  ...
    

11.21 <sup> element

This element is like the <sup> element in Section 4.5.16 of [HTML5].

Note: the down conversion to RFC2629 format replaces "xy" by "x^y".

See also <sup> (Section 12.22).

11.22 Extensions to Xml2rfc <artwork> element

Sometimes, artwork occurs inside lists. To get it indent properly in xml2rfc's text output, it needs to be indented in the source. This is sub-optimal, as this whitespace will also appear in the HTML output, where it's already indented due to HTML's semantics. As a workaround, a "x:indent-with" attribute can be specified, containing a string that will be prepended to each line when clean-for-DTD.xslt is run (see Section 13.4).

Furthermore, documents can contain code that might need to be marked as "code component" (<http://www.ietf.org/iesg/statement/copyright.html>). This can be done using "x:is-code-component".

Finally, when allowing pretty-printing of code (see "html-pretty-print" in Section 3.3, the "x:lang" attribute can used to explicitly opt into pretty-printing (the value is currently unused and ought to be set to an empty string).

11.23 Extensions to Xml2rfc <iref> element

The extension attribute below is allowed on the standard <iref> element:

  • x:for-anchor specifies that the <iref> will also be automatically inserted whenever the specified anchor is cross-referenced -- this may save entering lots of <iref> instances. As a special case, a value of "" (empty string) refers to the anchor attribute of the closest ancestor.

11.24 Extensions to Xml2rfc <list> element

The extension attribute below is allowed on the standard <list> element:

  • x:indent specifies the amount of indentation for list items in hanging lists. This can be useful when the output format, such as XSL-FO, does not support automatical formatting. The value takes an XSL-FO width, such as "5em". The default is length of longest label in characters times 0.8em.

Also, the <list> element can take <x:lt> child elements instead of <t>, allowing to insert multiple paragraphs into a single list item.

11.25 Extensions to Xml2rfc <rfc> element

The extension attributes below are allowed on the standard <rfc> element:

  • grddl:transformation can be used to reference a GRDDL transform.
  • x:maturity-level can be used to specify the IETF Standards Track Maturity Level of "proposed", "draft" or "internet" (see Section 4.1 of [RFC2026]).

11.26 Extensions to Xml2rfc <section> element

The extension attribute below is allowed on the standard <list> element:

  • x:fixed-section-number can be used to specify a fixed section number. This can be useful when formatting historic documents that used a different numbering style.

11.27 Extensions to Xml2rfc <xref> element

Three extension attributes are allowed on the standard <xref> element:

  1. x:sec can be specified to point to a specific section of the referenced document,
  2. x:rel may specify a relative reference to use when linking into the referenced document (if linking by section number is not available),
  3. x:fmt defines the text format to be used.

The following formats are defined for the x:fmt attribute:

, (Comma)
[reference], Section sec
()
[reference] (Section sec)
of
Section sec of [reference]
number
sec
none
No output (can be used to have xrefs to references without having them rendered as such)
sec
Section sec

These extensions are currently only supported for <xref> elements without child nodes.

If the processor knows how to reference the target section, it will generate a link directly to the target section, such as in [RFC2119], Section 5.


12. Experimental Support for XML2RFCv3 Vocabulary

rfc2629.xslt experimentally supports some elements from the "V3" vocabulary, defined in [XML2RFCV3]. This support is experimental, as the "v3" vocabulary is still being developed.

12.1 aside Element

12.2 bcp14 Element

12.3 blockquote Element

12.4 boilerplate Element

12.5 br Element

12.6 displayreference Element

12.7 dd Element

12.8 dl Element

12.9 dt Element

12.10 em Element

12.11 li Element

12.13 name Element

See Section 2.32 of [XML2RFCV3]. Currently only supported inside <references> and <section>.

12.14 ol Element

12.15 postalLine Element

12.16 refcontent Element

12.17 sourcecode Element

12.18 Extensions to reference Element

12.18.1 quoteTitle attribute

12.19 Extensions to section Element

12.19.1 numbered attribute

12.19.2 removeInRFC attribute

12.20 strong Element

12.21 sub Element

12.22 sup Element

12.23 svg Element

12.24 table Element

12.25 tbody Element

12.26 td Element

12.27 tfoot Element

12.28 th Element

12.29 thead Element

12.30 tr Element

12.31 tt Element

12.32 ul Element


13. Utilities

13.1 Checking References

check-references.xslt can be used to check all references to RFC- and ID-series IETF publications and to W3C publications (note this script requires local copies of <ftp://ftp.isi.edu/in-notes/rfc-index.xml> and <http://www.w3.org/2002/01/tr-automation/tr.rdf> and will use the XML status information provided at <http://tools.ietf.org/>).

If the document is supposed to be published on the IETF standards track, the desired level can be specified using the parameter intended-level as 'proposed', 'draft' or 'internet'. Alternatively, it can be specified inside the document using the attribute x:maturity-level on the <rfc> element (see Section 11.25).

Note: Downward references should be annotated using the <annotate> element, containing an <xref> to [BCP97].

When an XSLT 2.0 processor is used, links in the document can be checked as well using the link-check parameter ('yes' or 'no'). Note that this only works for http links to documents of type text/*.

For instance, as of 2008-07-12, the script produces for <http://greenbytes.de/tech/webdav/rfc2518.xml>:

> saxon rfc2518.xml check-references.xslt intended-status=PROPOSED \
  link-check=yes

Normative References:
ISO-11578: not checked
ISO-639: not checked
ISO-8601: not checked
REC-xml-19980210: [FirstEdition] obsoleted by REC-xml-20001006
REC-xml-names-19990114: [FirstEdition] obsoleted by
 REC-xml-names-20060816
RFC1766: [PROPOSED STANDARD] obsoleted by RFC3066 RFC3282
RFC2068: [PROPOSED STANDARD] obsoleted by RFC2616
RFC2069: [PROPOSED STANDARD] obsoleted by RFC2617
RFC2119: [BEST CURRENT PRACTICE] (-> BCP0014) ok
RFC2141: [PROPOSED STANDARD] ok
RFC2277: [BEST CURRENT PRACTICE] (-> BCP0018) ok
RFC2396: [DRAFT STANDARD] obsoleted by RFC3986
RFC2279: [DRAFT STANDARD] obsoleted by RFC3629

Informational References:
REC-PICS-labels-961031: [REC] ok
RFC1807: [INFORMATIONAL] ok
RFC2026: [BEST CURRENT PRACTICE] (-> BCP0009) ok
RFC2291: [INFORMATIONAL] ok
RFC2376: [INFORMATIONAL] obsoleted by RFC3023
RFC2413: [INFORMATIONAL] obsoleted by RFC5013
USMARC: not checked
WF: not checked

Link Targets
<http://www.w3.org/TR/1998/REC-xml-19980210>: ok
<http://www.w3.org/TR/1999/REC-xml-names-19990114>: ok
<http://www.dlib.org/dlib/july96/lagoze/07lagoze.html>: ok
<http://www.w3.org/pub/WWW/TR/REC-PICS-labels-961031.html>: ok

Recognized formats in the <seriesInfo> element are:

  • for RFCs, the name attribute must be "RFC", and the value attribute must be the number of the RFC,
  • for Internet Drafs, the name attribute must be "ID" or "Internet-Draft", and the value attribute must be the file name of the draft (including the two-digit running number, but excluding a file extension),
  • for W3C documents, the name attribute must be "W3C", must start with "W3C ", or must start with "World Wide Web Consortium ", and the value attribute must be the "shorthand" name of the specification, such as "REC-xml-19980210".

13.2 Generating Graphs from References

gen-reference-graph.xslt generates a graph of RFC dependencies, using the same base data as in check-references.xslt (see Section 13.1). Its output is a "dot" file, to be processed by GraphViz (see <http://www.graphviz.org/>).

The picture below shows the RFC dependencies in RFC2629.


(PNG output obtained from GraphViz)

13.3 Producing reference entries for books

amazon-asin.xslt uses the Amazon web services to generate a <reference> element for a given ASIN (ISBN).

For instance:

<?xml version="1.0" encoding="utf-8"?>
<references>
 <reference target="urn:isbn:0134516591">
   <front>
     <title>Simple Book, The: An Introduction to Internet Management,
               Revised Second Edition</title>
     <author surname="Rose"
                fullname="Marshall T. Rose" initials="M. T. ">
       <organization/>
     </author>
     <author surname="Marshall"
                fullname="Rose T. Marshall" initials="R. T.">
       <organization/>
     </author>
     <date year="1996" month="March"/>
   </front>
   <seriesInfo name="Prentice Hall" value=""/>
 </reference>
</references>

Note that the resulting XML usually requires checking, in this case Amazon's database is playing tricks with Marshall's name...

13.4 Down-converting to RFC2629bis DTD

clean-for-DTD.xslt can be used to down-convert some extensions to a format that is supported by the base xml2rfc distribution. Note that these extensions are experimental (feedback appreciated).

The following mappings are done:

  • <iref> elements inside <artwork> elements are moved in front of the enclosing <figure> element.
  • <xref> elements inside <artwork> are expanded just like in regular text (that is, the markup is stripped, but the element is replaced by the applicable replacement text).
  • <x:anchor-alias> elements get stripped.
  • <x:bcp14> elements get stripped.
  • <x:bb>, <x:bc> and <x:bt> elements get stripped.
  • <x:blockquote> elements get converted to indented text (through a <list> element).
  • <x:dfn> elements get stripped.
  • <x:h> elements get stripped.
  • <x:link> elements get stripped.
  • <x:lt> elements get collapsed into a single <lt> element with added <vspace> added to simulate paragraph breaks.
  • <x:note> elements get converted to indented text (through a <list> element).
  • <x:q> elements get stripped, with apostrophes added around the text.
  • <x:prose> elements are transformed into <seriesInfo> elements (which is an abuse of the element and only a workaround until xml2rfc gets a matching extension).
  • <x:ref> elements get replaced by <xref> elements, targetting either the anchor or another anchor with matching <x:anchor-alias> child element.

13.5 Extracting artwork

With extract-artwork.xslt, artwork elements named through the "name" attribute can be extracted. This can be used to automatically check their syntax (for instance, when ABNFs appear within a figure element).

For instance:

saxon rfc3986.xml extract-artwork.xslt name=uri.abnf

In addition, artwork of a specific type can be extracted, such as with:

saxon rfc3986.xml extract-artwork.xslt type=abnf

When extracting by type, artwork elements with a specified name can be excluded; this can be handy when the document uses some kind of schema language, and an appendix contains the collected schema, repeating definitions from earlier on. Example:

saxon rfc3986.xml extract-artwork.xslt type=abnf except-name=clschm

13.6 GRRDL

rfc2629grddl.xslt extracts RDF information. This is experimental work-in-progress. See <http://www.w3.org/TR/grddl/> for more information.

13.7 HTML Live Refresh

Experimental

The "HTML Live Refresh" mode allows to run a text editor and a browser side-by-side, with the browser auto-updating every few seconds, displaying the updated HTML, and automatically navigating to the part of the page that changed last.

The requirements for this mode are:

  1. A browser that supports the DOMParser and XSLTProcessor APIs.
  2. The ability to reload the source code and the XSLT code from within Javascript; in some browsers this is forbidden for "file:" URIs due to perceived security problems.

This feature is currently tested with:

  1. Mozilla Firefox, and
  2. Google Chome (where, to be able to reload from the local filesystem, Chrome needs to be started with the command line option --allow-file-access-from-files).

Use of this feature requires the inclusion of a processing instruction that holds the name of the XML source, such as:

<?rfc-ext refresh-from="draft-foo-bar-00.xml"?>

The optional parameters refresh-interval and refresh-xslt support changing the refresh interval (in seconds, defaulting to 10), and the name of the XSLT file to use (defaulting to "rfc2629.xslt").

To test this feature, start with a minimal source file like this:

<?xml-stylesheet type='text/xsl' href='rfc2629.xslt'?>
<?rfc-ext refresh-from="draft-foo-bar-00.xml"?> 
<rfc docName="draft-foo-bar-00" ipr="trust200902">
  <front>
    <title>Title Goes Here</title>
    <abstract>
      <t>Abstract</t>
    </abstract>
  </front>
</rfc>

...open it in both text editor and browser, start editing and of course ocasionally save.

13.8 Refreshing included material in the XML source

There are many methods for automatic inclusion of material in the XML source, such as the "include" processing instruction (see Section 3.1), external entities (Appendix C.1), or XInclude. In general, those share a common problem: the XML source file isn't self-contained, which makes it harder to submit it as Internet Draft.

The tool refresh-inclusions.sh does in-place replacement: it scans the source file for inclusion directives (expressed as XML processing instructions), and refreshes the included text with data from an external file. It will not modify the source file unless included material did actually change. When it does modify the source file, it will copy the original source to a backup file.

refresh-inclusions.sh can include both plain text (BEGINESCAPEDINC/ENDESCAPEDINC) and XML (BEGININC/ENDINC). The figure below was inserted using:

<?BEGINESCAPEDINC refresh-inclusions.sh ?>
...
<?ENDSCAPEDINC refresh-inclusions.sh ?>

(note that the SP character at the end of the directive is significant)

refresh-inclusions.sh:

#!/bin/sh
# Refresh file inclusions based on XML processing instructions
# 
# Copyright (c) 2006-2016, Julian Reschke (julian.reschke@greenbytes.de)
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 
# * Redistributions of source code must retain the above copyright notice,
#   this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
#   this list of conditions and the following disclaimer in the documentation
#   and/or other materials provided with the distribution.
# * Neither the name of Julian Reschke nor the names of its contributors
#   may be used to endorse or promote products derived from this software
#   without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

expand() {

  # remember whether we started with CRLF (assumes that we have dos2unix)
  CRLF=$(dos2unix -ic "$1" 2>/dev/null | tr -d ' ')
  
  cat "$1" | awk ' 

  function filecontents(filename) {
    while (getline < filename > 0) {
      fc[filename] = fc[filename] $0 "\n"
    }
    return fc[filename]
  }

  BEGIN {
    includefile = "";
    includeescapedfile = "";
  }
  
  # start include (verbatim mode)
  /<\?BEGININC .* \?>$/ {
    print
    keyword = "<?BEGININC " 
    extract = match($0, /<\?BEGININC .* \?>$/)
    includefile = substr($0, RSTART + length(keyword),
                    RLENGTH - 3 - length(keyword))
    output = filecontents(includefile)
    printf("%s", output)
  }
  
  # start include (escape-for-XML mode)
  /<\?BEGINESCAPEDINC .* \?>$/ {
    print
    keyword = "<?BEGINESCAPEDINC " 
    extract = match($0, /<\?BEGINESCAPEDINC .* \?>$/)
    includeescapedfile = substr($0, RSTART + length(keyword),
                           RLENGTH - 3 - length(keyword))
    output = filecontents(includeescapedfile)
    # escape ampersand, less-than, and greater-than
    # when part of a CDATA end marker
    gsub(/&/, "\\&amp;", output)
    gsub(/</, "\\&lt;", output)
    gsub(/]]>/, "]]\\&gt;", output)
    printf("%s", output)
  }

  # end include (verbatim mode)
  /^<\?ENDINC .* \?>/ {
    if ($2 != includefile) {
      printf ("unexpected ENDINC, got %s but expected %s\n", $2,
        includefile) >> "/dev/stderr"
    }
    includefile = "";
  }
  
  # end include (escape-for-XML mode)
  /^<\?ENDESCAPEDINC .* \?>/ {
    if ($2 != includeescapedfile) {
      printf ("unexpected ENDESCAPEDINC, got %s but expected %s\n", $2,
        includeescapedfile) >> "/dev/stderr"
    }
    includeescapedfile = "";
  }

  #default
  {
    if (includefile == "" && includeescapedfile == "") {
      print
    }
  }
  
  END {
    if (includefile != "") {
      printf ("missing ENDINC for %s\n",
        includefile) >> "/dev/stderr"
    }
    if (includeescapedfile != "") {
      printf ("missing ENDESCAPEDINC for %s\n",
        includeescapedfile) >> "/dev/stderr"
    }
  }
  
  ' > $$
  
  # restore CRLF if needed
  if [ -n "$CRLF" ]; then
    FNN=$(echo "$1" | tr -d ' ')
    [ "$FNN" = "$CRLF" ] && unix2dos -q $$
  fi
  
  # check for changes
  cmp -s "$1" $$ || (
    cp -v "$1" "$1".ri.bak
    cp $$ "$1"
    echo "$1" updated )
  
  rm -f $$
}

[ $# -ne 0 ] || ( echo "refresh-inclusions.sh file..." >&2 ; exit 2 )

for i in $*
do
  expand $i
done

14. Informative References

[BCP97]
Klensin, J. and S. Hartman, “Handling Normative References to Standards-Track Documents”, BCP 97, RFC 4897, June 2007, <http://www.rfc-editor.org/info/bcp97>.
[DC-HTML]
Johnston, P. and A. Powell, “Expressing Dublin Core metadata using HTML/XHTML meta and link elements”, Dublin Core Metadata Initiative, August 2008, <http://dublincore.org/documents/2008/08/04/dc-html/>.
[HTML5]
Hickson, I., Berjon, R., Faulkner, S., Leithead, T., Doyle Navara, E., O'Connor, E., and S. Pfeiffer, “HTML5”, W3C Recommendation REC-html5-20141028, October 2014, <http://www.w3.org/TR/2014/REC-html5-20141028/>.
Latest version available at <http://www.w3.org/TR/html5/>.
[RFC2026]
Bradner, S., “The Internet Standards Process -- Revision 3”, BCP 9, RFC 2026, DOI 10.17487/RFC2026, October 1996, <http://www.rfc-editor.org/info/rfc2026>.
[RFC2045]
Freed, N. and N. Borenstein, “Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies”, RFC 2045, DOI 10.17487/RFC2045, November 1996, <http://www.rfc-editor.org/info/rfc2045>.
[RFC2119]
Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>.
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1”, RFC 2616, DOI 10.17487/RFC2616, June 1999, <http://www.rfc-editor.org/info/rfc2616>.
[RFC2629]
Rose, M., “Writing I-Ds and RFCs using XML”, RFC 2629, DOI 10.17487/RFC2629, June 1999, <http://www.rfc-editor.org/info/rfc2629>.
[RFC2648]
Moats, R., “A URN Namespace for IETF Documents”, RFC 2648, DOI 10.17487/RFC2648, August 1999, <http://www.rfc-editor.org/info/rfc2648>.
[RFC2731]
Kunze, J., “Encoding Dublin Core Metadata in HTML”, RFC 2731, DOI 10.17487/RFC2731, December 1999, <http://www.rfc-editor.org/info/rfc2731>.
[RFC5234]
Crocker, D., Ed. and P. Overell, “Augmented BNF for Syntax Specifications: ABNF”, STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008, <http://www.rfc-editor.org/info/rfc5234>.
[RFC7230]
Fielding, R., Ed. and J. Reschke, Ed., “Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing”, RFC 7230, DOI 10.17487/RFC7230, June 2014, <http://www.rfc-editor.org/info/rfc7230>.
[RFC7749]
Reschke, J., “The "xml2rfc" Version 2 Vocabulary”, RFC 7749, DOI 10.17487/RFC7749, February 2016, <http://www.rfc-editor.org/info/rfc7749>.
[RNC]
Clark, J., “RELAX NG Compact Syntax”, OASIS, Nov 2002, <http://www.oasis-open.org/committees/relax-ng/compact-20021121.html>.
[XHTML2]
Birbeck, M., Gylling, M., McCarron, S., Pemberton, S., Axelsson, J., Dubinko, M., Epperson, B., Ishikawa, M., and A. Navarro, “XHTML(tm) 2.0”, W3C Group Note NOTE-xhtml2-20101216, December 2010, <http://www.w3.org/TR/2010/NOTE-xhtml2-20101216>.
Latest version available at <http://www.w3.org/TR/xhtml2>.
[XML]
Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and F. Yergeau, “Extensible Markup Language (XML) 1.0 (Fifth Edition)”, W3C Recommendation REC-xml-20081126, November 2008, <http://www.w3.org/TR/2008/REC-xml-20081126/>.
Latest version available at <http://www.w3.org/TR/xml>.
[XML2RFCV3]
Hoffman, P., “The "xml2rfc" version 3 Vocabulary”, Internet-Draft draft-iab-xml2rfc-04 (work in progress), June 2016.
[XSL-FO]
Berglund, A., “Extensible Stylesheet Language (XSL) Version 1.1”, W3C Recommendation REC-xsl11-20061205, December 2006, <http://www.w3.org/TR/2006/REC-xsl11-20061205/>.
Latest version available at <http://www.w3.org/TR/xsl11/>.

A. RELAX NG Compact Schema

The RelaxNG schema ([RNC]) below can be used to validate input documents (for instance, with Jing).

Note that this is work in progress, and doesn't yet cover all extensions completely.

# WORK IN PROGRESS! PLEASE REPORT PROBLEMS TO THE AUTHOR.

# Define our extension namespace
namespace x = "http://purl.org/net/xml2rfc/ext"

# Define GRDDL namespace
namespace grddl = "http://www.w3.org/2003/g/data-view#"

# Define RDF namespace
namespace rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"

# Define SVG namespace
namespace svg = "http://www.w3.org/2000/svg"

# Define XInclude namespace
namespace xi = "http://www.w3.org/2001/XInclude"

# Include rfc2629bis RNC grammar
include "rfc2629.rnc" {
  
  # Redefine <annotation> to allow more markup
  annotation =
    element annotation {
      attlist.annotation,
      (TEXT
        | xref
        | eref
        | iref
        | cref
        | spanx
        | v3_tt
        )*
    }

  # Redefine <artwork> to allow markup
  artwork =
    element artwork {
      attlist.artwork,
      attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
      ( v3_svg |
        (TEXT
          | eref 
          | iref 
          | spanx 
          | xref
          | v3_em
          | v3_strong
          | x_abnf-char-sequence
          | x_bb
          | x_bc
          | x_bcp14
          | x_bt
          | x_highlight
          | x_length-of
          | x_parse-xml
          | x_ref
          | x_span
          | x_x)*
        )
    }

  # Redefine <back> to allow displayreference
  back =
    element back {
      attlist.back,
      v3_displayreference*,
      references*,
      section*
    }

  # Redefine <c> to allow our extension elements
  c =
    element c {
      attlist.c,
      (TEXT
        | xref
        | eref 
        | iref 
        | cref 
        | spanx 
        | v3_em
        | v3_strong
        | v3_tt
        | x_ref)*
    }

  # Redefine <cref> to allow more child elements
  cref =
    element cref {
      attlist.cref,
      (TEXT
        | eref
        | xref)*
    }

  # Redefine <figure> to allow more child elements
  figure =
    element figure {
      attlist.figure,
      attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
      v3_name?,
      iref*,
      preamble?,
      ( artwork | v3_sourcecode),
      postamble?
    }

  # Redefine <front> to allow boilerplate
  front =
    element front {
      attlist.front,
      title,
      seriesInfo*,
      author+,
      date?,
      area*,
      workgroup*,
      keyword*,
      abstract?,
      note*,
      v3_boilerplate?
    }
  
  # Redefine <list> element to allow <x:lt> child elements
  \list =
    element list {
      attlist.list,
      (t+ | x_lt+)
    }    
    
  # Redefine <preamble> to allow our extension elements
  preamble =
    element preamble {
      attlist.preamble,
      (TEXT
        | xref
        | eref
        | iref
        | cref
        | spanx
        | v3_em
        | v3_strong
        | v3_tt
        | x_anchor-alias
        | x_bcp14)*
  }

  # Redefine <postal> to allow <postalLine>
  postal =
    element postal {
      (
        (city
          | code
          | country
          | region
          | street)*
        | v3_postalLine+)
    }

  # Redefine <postamble> to allow our extension elements
  postamble =
    element postamble {
      attlist.postamble,
      (TEXT
        | xref
        | eref
        | iref
        | cref
        | spanx
        | v3_em
        | v3_strong
        | v3_tt
        | x_bcp14)*
    }

  # Redefine <reference> to allow our extension elements
  reference =
    element reference {
      attlist.reference,
      front,
      seriesInfo*,
      x_prose?,
      v3_refcontent?,
      format*,
      annotation*,
      x_source?
    }

  # Redefine <references> to allow our <name>
  references =
    element references {
      attribute title { text }?,
      attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
      v3_name?,
      (reference
       | xi_include)+
    }

  # Redefine <rfc> to allow our extension elements
  rfc =
    element rfc {
      attlist.rfc,
      v3_link*,
      x_link*,
      x_feedback?,
      x_assign-section-number*,
      front,
      middle,
      back?
    }

  # Redefine <section> to allow our extension elements
  section =
    element section {
      attlist.x_section,
      (t
       | figure
       | texttable
       | iref
       | section
       | v3_aside
       | v3_blockquote
       | v3_dl
       | v3_name
       | v3_ol
       | v3_sourcecode
       | v3_table
       | v3_ul
       | x_anchor-alias
       | x_blockquote
       | x_include-author
       | x_note
       | rdf_Description)*
    }

  # Redefine <spanx> to allow some markup
  spanx =
    element spanx {
      attlist.spanx,
      (TEXT
        | iref
        | xref
        | x_ref)*
    }

  # Redefine <t> to allow our extension elements
  t =
    element t {
      attlist.t,
      (TEXT
       | \list
       | figure
       | xref
       | eref
       | iref
       | cref
       | spanx
       | vspace
       | v3_bcp14
       | v3_em
       | v3_strong
       | v3_sub
       | v3_sup
       | v3_tt
       | x_abnf-char-sequence
       | x_anchor-alias
       | x_bcp14
       | x_dfn
       | x_h
       | x_q
       | x_ref
       | x_span
       | x_sup)*
    }
}

# Extend attribute set for <abstract>
attlist.abstract &=
  attribute pn { text }? # (see [XML2RFCV3], Appendix B.2)

# Allow extension attributes on <artwork> (Section 11.22)
attlist.artwork &=
  attribute x:indent-with { ATEXT }?,
  attribute x:lang { "" }?,
  attribute x:is-code-component { "no" | "yes" }?

# Allow anchor and x:annotation attributes on <author>
attlist.author &=
  attribute anchor { xsd:ID }?,
  attribute x:annotation { ATEXT }?
  
# Extend attribute set for <c> (see Section 11.23)
attlist.c &=
  attribute anchor { xsd:ID }?

# Extend attribute set for <iref> (see Section 11.23)
attlist.iref &=
  attribute x:for-anchor { ATEXT }?

# Extend attribute set for <list> (see Section 11.24)
attlist.list &=
  attribute x:indent { ATEXT }?

# Extend attribute set for <preamble>
attlist.preamble &=
  attribute anchor { xsd:ID }?

# Extend attribute set for <reference>
attlist.reference &=
  attribute quoteTitle { "false" | "true" }? # (see Section 12.18.1)

# Extend attribute set for <references>
attlist.references &=
  attribute pn { text }? # (see [XML2RFCV3], Appendix B.2)

# Extend attribute set for <rfc>
attlist.rfc &=
  attribute grddl:transformation { ATEXT }?,
  attribute x:maturity-level { "proposed" | "draft" | "internet" }?,
  attribute indexInclude { "true" | "false" }?, # (see [XML2RFCV3], Section 2.45.4)
  attribute tocDepth { text }?, # (see [XML2RFCV3], Section 2.45.14)
  attribute tocInclude { "true" | "false" }?, # (see [XML2RFCV3], Section 2.45.15)
  attribute sortRefs { "true" | "false" }?, # (see [XML2RFCV3], Section 2.45.11)
  attribute symRefs { "true" | "false" }?, # (see [XML2RFCV3], Section 2.45.13)
  attribute version { text }? # (see [XML2RFCV3], Section 2.45.13)

# Extend/Relax attribute set for <section> (see Section 11.26)
attlist.x_section &=
  attribute anchor { xsd:ID }?,
  attribute title { ATEXT }?,
  attribute toc { "include" | "exclude" | "default" }?,
  attribute numbered { "false" | "true" }?, # see Section 12.19.1
  attribute removeInRFC { "false" | "true" }?, # see Section 12.19.2
  attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
  attribute x:fixed-section-number { ATEXT }?

# Allow anchor attribute on <spanx>
attlist.spanx &=
  attribute anchor { xsd:ID }?

# Extend attribute set for <c> (see Section 11.23)
attlist.t &=
  attribute pn { text }? # (see [XML2RFCV3], Appendix B.2)

# Allow x:quotes attribute on <title>
attlist.title &=
  attribute x:quotes { "true" | "false" }?

# Allow annotation attribute on <uri>
attlist.uri &=
  attribute x:annotation { ATEXT }?

# Extend attribute set for <xref> (see Section 11.27)
attlist.xref &=
  attribute x:fmt  { "()" | "," | "of" | "number" | "sec" |
                     "none" }?,
  attribute x:rel  { ATEXT }?,
  attribute x:sec  { ATEXT }?

# Side Note (see Section 12.1)
v3_aside =
  element aside {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    t+
  }

# BCP14/RFC2119 keywords (see Section 12.2)
v3_bcp14 =
  element bcp14 {
    "MAY"
    | "MUST"
    | "MUST NOT"
    | "NOT RECOMMENDED"
    | "OPTIONAL"
    | "RECOMMENDED"
    | "REQUIRED"
    | "SHALL"
    | "SHALL NOT"
    | "SHOULD"
    | "SHOULD NOT"
  }

# Blockquote (see Section 12.3)
v3_blockquote =
  element blockquote {
    attribute anchor { xsd:ID }?,
    attribute cite { URI }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    t+
  }

# Boilerplate (see Section 12.3)
v3_boilerplate =
  element boilerplate {
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    section+
  }

# Line Break (see Section 12.5)
v3_br =
  element br {
    empty
  }

# Mapping of reference names to display names (see Section 12.6)
v3_displayreference =
  element displayreference {
    attribute target { xsd:IDREF },
    attribute to { ATEXT }
  }

# Definition List Description Element (see Section 12.7)
v3_dd =
  element dd {
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    ((t
      | v3_dl)+ | 
    (TEXT
      | cref
      | eref
      | iref
      | xref
      | v3_em
      | v3_tt
      | v3_strong)*
    )
  }

# Definition List (see Section 12.8)
v3_dl =
  element dl {
    attribute hanging { "false" | "true" }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    attribute spacing { "normal" | "compact" }?,
    (v3_dt, v3_dd)+
  }

# Definition List Description Term (see Section 12.9)
v3_dt =
  element dt {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    (TEXT
      | cref
      | eref
      | iref
      | xref
      | v3_em
      | v3_tt
      | v3_strong)*
  }

# Emphasized Text (see Section 12.10)
v3_em =
  element em {
    (TEXT
      | xref
      | v3_strong
      | x_ref)*
  }

# Definition List (see Section 12.11)
v3_li =
  element li {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    ((v3_dl | v3_ol  | t | v3_ul )+ 
      | 
    (TEXT
      | cref
      | eref
      | iref
      | xref
      | v3_em
      | v3_strong
      | v3_sub
      | v3_sup
      | v3_tt
      | x_ref)*
    )
  }

# Container for additional links (see Section 12.12)
v3_link =
  element link {
    attribute href { text },
    attribute rel { text }?
  }

# Section/Figure/Table Name (see Section 12.13)
v3_name =
  element name {
    attribute slugifiedName { text }?, # (see [XML2RFCV3], Appendix B.2)
    (TEXT
      | cref
      | v3_em
      | v3_tt
      | xref)*
  }

# Ordered List (see Section 12.14)
v3_ol =
  element ol {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    attribute start { TEXT }?,
    attribute group { TEXT }?,
    attribute type { TEXT }?,
    v3_li+
  }

# Line in postal address (see Section 12.15)
v3_postalLine =
  element postalLine {
    TEXT
  }

# additional content for references (see Section 12.16)
v3_refcontent =
  element refcontent {
    (TEXT
      | v3_em)*
  }

# Source Code (see Section 12.17)
v3_sourcecode =
  element sourcecode {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    attribute x:lang { "" }?,
    TEXT
  }

# Emphasized Text (see Section 12.20)
v3_strong =
  element strong {
    attribute anchor { xsd:ID }?,
    (TEXT
      | xref
      | v3_em
      | x_ref)*
  }

# Subscript (see Section 12.21)
v3_sub =
  element sub {
    (TEXT)*
  }

# Superscript (see Section 12.22)
v3_sup =
  element sup {
    (TEXT)*
  }

# Table (see Section 12.24)
v3_table =
  element table {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    v3_name?,
    iref*,
    v3_thead?,
    v3_tbody,
    v3_tfoot?
  }

# Table Body (see Section 12.25)
v3_tbody =
  element tbody {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    v3_tr+
  }

# Table Contents Cell (see Section 12.26)
v3_td =
  element td {
    attribute anchor { xsd:ID }?,
    attribute align { "left" | "center" | "right" }?,
    attribute colspan { text }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    attribute rowspan { text }?,
    ( (t
       | v3_dl
       | v3_ol
       | v3_sourcecode
       | v3_ul
      )+
      | (TEXT
         | v3_bcp14
         | v3_br
         | cref
         | v3_em
         | eref
         | v3_strong
         | v3_sub
         | v3_sup
         | v3_tt
         | xref)*
    )
  }

# Table Footer (see Section 12.27)
v3_tfoot =
  element tfoot {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    v3_tr
  }

# Table Header Cell (see Section 12.28)
v3_th =
  element th {
    attribute anchor { xsd:ID }?,
    attribute align { "left" | "center" | "right" }?,
    attribute colspan { text }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    attribute rowspan { text }?,
    ( (t
       | v3_dl
       | v3_ol
       | v3_sourcecode
       | v3_ul
      )+
      | (TEXT
         | v3_bcp14
         | v3_br
         | cref
         | v3_em
         | eref
         | v3_strong
         | v3_sub
         | v3_sup
         | v3_tt
         | xref)*
    )
  }

# Table Head (see Section 12.29)
v3_thead =
  element thead {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    v3_tr
  }

# Table Row (see Section 12.30)
v3_tr =
  element tr {
    attribute anchor { xsd:ID }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    (
      v3_td
      | v3_th
    )+
  }

# Monospaced Text (see Section 12.31)
v3_tt =
  element tt {
    (TEXT
      | xref
      | v3_em
      | x_ref)*
  }

# Unordered List (see Section 12.32)
v3_ul =
  element ul {
    attribute anchor { xsd:ID }?,
    attribute empty { TEXT }?,
    attribute pn { text }?, # (see [XML2RFCV3], Appendix B.2)
    v3_li+
  }

# SVG (see Section 12.23)
v3_svg =
  element svg:svg {
    (attribute * { text }
        | text
        | anySVGElement)*
  }

 anySVGElement =
    element svg:* {
       (attribute * { text }
        | text
        | anySVGElement)*
    }
      
# Conversion to ABNF char sequence (see Section 11.1)
x_abnf-char-sequence =
  element x:abnf-char-sequence {
    TEXT
  }

# Aliasing of anchors (see Section 11.2)
x_anchor-alias =
  element x:anchor-alias {
    attribute value { TEXT },
    empty
  }

# Supply feedback links (see Section 11.9)
x_feedback =
  element x:feedback {
    attribute template { TEXT },
    empty
  }

# Including Author information
# (experimental)
x_include-author =
  element x:include-author {
    attribute target { xsd:IDREF }
  }

# Setting section numbers for internally generated sections
# (experimental)
x_assign-section-number =
  element x:assign-section-number {
    attribute builtin-target { "authors" },
    attribute number { TEXT },
    empty
  }

# Bottom line of box drawing (see Section 11.4)
x_bb =
  element x:bb {
    (TEXT
      | iref
      | xref
      | x_bb
      | x_bc
      | x_bt
      | x_ref)* 
  }

# Center line of box drawing (see Section 11.5)
x_bc =
  element x:bc {
    (TEXT
      | iref
      | spanx
      | xref
      | x_bb
      | x_bc
      | x_bt
      | x_ref)* 
  }

# BCP14/RFC2119 keywords (see Section 11.3)
x_bcp14 =
  element x:bcp14 {
    "MAY"
    | "MUST"
    | "MUST NOT"
    | "NOT RECOMMENDED"
    | "OPTIONAL"
    | "RECOMMENDED"
    | "REQUIRED"
    | "SHALL"
    | "SHALL NOT"
    | "SHOULD"
    | "SHOULD NOT"
  }
  
# Blockquote (see Section 11.6)
x_blockquote =
  element x:blockquote {
    attribute anchor { xsd:ID }?,
    attribute cite { URI }?,
    t+
  }

# Top line of box drawing (see Section 11.7)
x_bt =
  element x:bt {
    (TEXT
      | iref
      | xref
      | x_bb
      | x_bc
      | x_bt
      | x_ref)* 
  }

# declaration of definition in external reference
x_defines =
  element x:defines {
    TEXT
  }

# Definition (see Section 11.8)
x_dfn =
  element x:dfn {
    attribute anchor { xsd:ID }?,
    (TEXT
      | iref)*
  }
  
# Heading (see Section 11.10)
x_h =
  element x:h {
    TEXT
  }

# Heading (see Section 11.11)
x_highlight =
  element x:highlight {
    TEXT
  }

# Length Measurement (see Section 11.12)
x_length-of =
  element x:length-of {
    attribute indented { NUMBER }?,
    attribute target { xsd:IDREF },
    empty
  }

# Link (see Section 11.13)
x_link =
  element x:link {
    attribute basename { URI }?,
    attribute href { URI }?,
    attribute title { TEXT }?,
    attribute rel { TEXT },
    empty
  }
  
# Extended list item (see Section 11.14)
x_lt =
  element x:lt {
    attribute anchor { xsd:ID }?,
    attribute hangText { TEXT }?,
    t+
  }

# Note (see Section 11.15)
x_note =
  element x:note {
    attribute anchor { xsd:ID }?,
    t+
  }

# Signal XML content (see Section 11.16)
x_parse-xml =
  element x:parse-xml {
    (TEXT
      | xref)* 
  }

# Inline prose in a reference (see Section 11.17)
x_prose =
  element x:prose {
    TEXT
  }

# Inline quote (see Section 11.18)
x_q =
  element x:q {
    TEXT
  }

# Anchor reference (see Section 11.19)  
x_ref =
  element x:ref {
    attribute anchor { xsd:ID }?,
    TEXT
  }

# source information (see Section 11.20)  
x_source =
  element x:source {
    attribute basename { ATEXT }?,
    attribute href { URI },
    x_defines*
  }

# superscript (see Section 11.21)
x_sup =
  element x:sup {
    TEXT
  }

# Inline Span 
x_span =
  element x:span {
    attribute anchor { xsd:ID }?,
    attribute x:lang { "" }?,
    (TEXT
      | x_parse-xml)* 
  }

# Nop (for alignment in source)
x_x =
  element x:x {
    empty
  }

# XInclude
xi_include =
  element xi:include {
    attribute href { text },
    empty
  }

# Embed RDF statements 
rdf_Description =
  element rdf:Description {
    rdf_content
  }
  
rdf_content =
  ( TEXT | element * { rdf_content })*

B. Implementation Notes

B.1 Recognized type attributes for <artwork> element

Specific values in the <artwork> element's "type" attribute are recognized and cause a different visual style to be used:

TypeComment
abnfABNF as per [RFC5234]
abnf2045ABNF as per [RFC2045]
abnf2616ABNF as per [RFC2616], Section 2.1
abnf7230ABNF as per [RFC7230], Section 1.2
application/relax-ng-compact-syntaxRelax NG Compact Syntax as per [RNC]
application/xml-dtdXML DTD
codemonospaced text (with outline)
drawingdrawing (with outline)
examplemonospaced text (with outline)
inlinemonospaced text (no outline)
message/http; msgtype="request"HTTP message, as per [RFC2616], Section 19.1
message/http; msgtype="response"HTTP message, as per [RFC2616], Section 19.1

C. Examples

C.1 Using the 'Internal Subset'

The prolog of the XML document can both be used to refer to an external DTD, and also to define internal entities (Section 2.8 of [XML]):

<?xml version="1.0"?>
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>

<!DOCTYPE rfc SYSTEM "rfc2629.dtd" [

  <!-- use "&MAY;" for a BCP 14 "MAY", see Section 11.3 -->
  <!ENTITY MAY
  "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">

  <!-- re-declare "&nbsp;" as code point 160 (non-breaking space) -->
  <!-- you may need this for UAs that do not read external DTDs -->
  <!ENTITY nbsp
  "&#160;">

  <!-- allow later RFC2616 reference using "&rfc2616;" -->
  <!-- the data will be fetched from xml.resource.org -->
  <!ENTITY rfc2616 SYSTEM
  "http://xml.resource.org/public/rfc/bibxml/reference.RFC.2616.xml">

  <!-- allow a custom reference using "&mydraft;" -->
  <!-- the data will be fetched from the same location as the 
       source file -->
  <!ENTITY mydraft SYSTEM "reference.mydraft.xml">
]>

Note: including entities from a remote site will not work in Firefox, see <https://bugzilla.mozilla.org/show_bug.cgi?id=22942>.

C.2 Customization

The XSLT code can be customized by creating a custom XSLT file that uses <xsl:import> to include the original code, and just overrides particular rules.

For instance, the code below overrides several attributes in rfc2629toFO.xslt, changing the color, spacing and font family for headers.

<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
               version="1.0">

  <xsl:import href="rfc2629toFO.xslt"/>
  
  <xsl:attribute-set name="h1">
    <xsl:attribute name="color">darkblue</xsl:attribute>
    <xsl:attribute name="font-family">sans-serif</xsl:attribute>
    <xsl:attribute name="space-before">24pt</xsl:attribute>
  </xsl:attribute-set>
  
  <xsl:attribute-set name="h2">
    <xsl:attribute name="color">darkblue</xsl:attribute>
    <xsl:attribute name="font-family">sans-serif</xsl:attribute>
    <xsl:attribute name="space-before">18pt</xsl:attribute>
    <xsl:attribute name="space-after">3pt</xsl:attribute>
  </xsl:attribute-set>
  
  <xsl:attribute-set name="h3">
    <xsl:attribute name="color">darkblue</xsl:attribute>
    <xsl:attribute name="font-family">sans-serif</xsl:attribute>
    <xsl:attribute name="space-before">16pt</xsl:attribute>
    <xsl:attribute name="space-after">2pt</xsl:attribute>
  </xsl:attribute-set>

</xsl:transform>

D. Producing the IETF 'Boilerplate'

Various attributes of the <rfc> element plus some child elements of <front> affect the automatically generated parts of the front page, such as the tabular information at the beginning, the "Status Of This Memo", and the "Copyright Notice".

When submitting an Internet Draft, this "boilerplate" is checked by "Idnits" (<http://tools.ietf.org/tools/idnits/>) for compliance with the current Intellectual Property rules, and thus it is important to set the correct values.

Furthermore, the RFC Production Center uses RFC2629-based tools to generate the final RFC text, so the more accurate the supplied information is, the less additional work is left, and the risk for errors in producing the final (and immutable!) document is reduced.

The individual attributes on the <rfc> element are discussed in detail in Appendix A of [RFC7749].


E. License

Copyright (c) 2006-2016, Julian Reschke (julian.reschke@greenbytes.de)

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


Index

A B C D E F G H I J K L M N O P Q R S T U V X


Author's Address

Julian F. Reschke
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155
Germany
EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/