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Xml2rfc generates RFCs and IETF drafts from document source in XML according to the IETF xml2rfc v2 and v3 vocabularies.

Project description


The IETF uses a specific format for the standards and other documents it publishes as RFCs, and for the draft documents which are produced when developing documents for publications. There exists a number of different tools to facilitate the formatting of drafts and RFCs according to the existing rules, and this tool, xml2rfc, is one of them. It takes as input an xml file which contains the text and meta-information about author names etc., and transforms it into suitably formatted output. The input xml file should follow the grammars in RFC7749 (for v2 documents) or RFC7991 (for v3 documents). Note that the grammar for v3 is still being refined, and changes will eventually be captured in the bis draft for 7991. Changes not yet captured can be seen in the xml2rfc source v3.rng.

xml2rfc provides a variety of output formats. See the command line help for a full list of formats. It also provides conversion from v2 to v3, and can run the preptool on its input.


Installation of the python package is done as usual with ‘pip install xml2rfc’, using appropriate switches and/or sudo.

Installation of support libraries for the PDF-formatter

In order to generate PDFs, xml2rfc uses the WeasyPrint module, which depends on external libaries that must be installed as native packages on your platform, separately from the xml2rfc install.

First, install the Cairo, Pango, and GDK-PixBuf library files on your system. See installation instructions on the WeasyPrint Docs:

(Python 3 is not needed if your system Python is 2.7, though).

(On some OS X systems with System Integrity Protection active, you may need to create a symlink from your home directory to the library installation directory (often /opt/local/lib):

ln -s /opt/local/lib ~/lib

in order for weasyprint to find the installed cairo and pango libraries. Whether this is needed or not depends on whether you used macports or homebrew to install cairo and pango, and the homebrew / macport version.)

Next, install the pycairo and weasyprint python modules using pip. Depending on your system, you may need to use ‘sudo’ or install in user-specific directories, using the –user switch. On OS X in particular, you may also need to install a newer version of setuptools using –user before weasyprint can be installed. If you install with the –user switch, you may need to also set PYTHONPATH, e.g.,


for Python 2.7.

The basic pip commands (modify as needed according to the text above) are:

pip install ‘pycairo>=1.18’ ‘weasyprint<=0.42.3’

With these installed and available to xml2rfc, the –pdf switch will be enabled.

For PDF output, you also need to install the Noto font set. Download the full set from, and install as appropriate for your platform.


xml2rfc accepts a single XML document as input and outputs to one or more conversion formats.

Basic Usage: xml2rfc SOURCE [options] FORMATS...

Run xml2rfc --help for a full listing of command-line options.


Version 2.20.0 (26 Feb 2019)

This release changes the rendering of <xref> elements with text content by v3 formatters, and reintroduces <xref format=”none”> under v3 in order to properly cover the combinatorial space of rendering of <xref> with and without text content. It fixes a number of issues, including a somewhat unexpected issue with namespace normalization, and improves the rendering output in some edge cases. More details from the commit log:

  • Removed namespace cleanup and normalisation during the v2v3 conversion, as it can have negative effects for inlined <svg> when the SVG namespace is specified in multiple places.
  • Changed handling of reference//author entries with fullname but without initials and surname in order to derive those the same way for references as it’s done in other places.
  • Dropped support for Py34. Support is now Py27 (untill end 2019), and Python 3.5 - 3.7.
  • Tweaked the CSS for bcp14 keyword elements.
  • Fixed a problem where a temporary valuable name stomped on a method-wide name.
  • Fixed a problem where <xref> “relative” attributes were treated as fragment identifiers instead of as relative URL paths.
  • Improved the placeholder text emitted by the v3 text renderer for artwork without ascii-art.
  • Removed stripping of the now (again) functional <xref> format value “none” from the v2v3 converter.
  • Tweaked the rendering of <xref> having both derivedContent (section information, for instance) and text content, to generate hyperlinks to the xref target for both of them. Simplified the html renderer by eliminating extra code for <relref>, now covered by the generic <xref> code.
  • Fixed a problem with a missing hash character between path and fragment identifiers in derivedLink generation.
  • Added a conversion of <relref> elements to the generic <xref> form to preptool. Tweaked a debug print statement.
  • Added An SVG diagram of the processing flow for v2 and v3 documents, used by xml2rfc3.rst, to doc/
  • Added an rST-formatted Introduction to xml2rfc version 3 to doc/

Version 2.19.1 (16 Feb 2019)

This is a small bugfix release. From the commit log:

  • Removed some linux-specific code.
  • Fixed a problem with the handling of comments and PIs inside text blocks.

Version 2.19.0 (14 Feb 2019)

Changed handling of alternative artwork

The way <artwork> has been specified to handle the presence of both SVG artwork and text fallback (in Section 2.5 of [RFC7991]) has the result that any SVG content has to be placed as a data: URL in the “src” attribute when an ascii-art fallback is present. This makes the SVG effectively uneditable once the preptool has been run, even if the SVG artwork was originally provided as a regular SVG XML file external to the document XML file.

In order to be able to more easily deal with alternative instances of artwork, and in the future possibly deal smoothly with a wider number of alternative artwork formats than is currently provided for, a new element <artset> could be introduced, presenting a set of alternative artwork executions. This would let the renderer pick the most appropriate <artwork> instance for its format from the alternatives present within an <artset> element, based on the “type” attribute of each enclosed <artwork> element.

If more than one <artwork> element is found within an <artset> element, with the same “type” attribute, the renderer could select the first one, or possibly choose between the alternative instances based on the output format and some quality of the alternative instances that made one more suitable than the other for that particular format, such as size, aspect ratio, or whatnot.

Implementation: Xml2rfc as of version 2.18.0 implements this, with a

preference list when rendering to HTML and PDF of ( “svg”, “binary-art”, “ascii-art” ), while the text renderer uses the list ( “ascii-art”, ) – i.e., one entry only. The Relax-NG compact schema used for <artset> is this:

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

The <artset> element can occur anywhere an <artwork> element can occur. The first anchor on an <artwork> element within an <artset> element will be promoted to the <artset> element if it has none; apart from that, anchors on <artwork> elements within an <artset> element will be removed by the preptool.

Additionally, this release contains some other fixes and changes. From the commit log:

  • Normalized the expansion of <xref> to be more consistent conceptually and across renderings. Added back rendering support for format=’none’.
  • Added another exception class to the import exception catch for pango, to avoid a crash in some environments.
  • Applied a patch from to improve the xml2rfc description.
  • Disallow lxml 4.3.1, as it can cause segfaults with some Python versions. Fixes issue #393.
  • Put back LICENCE which has been lost from the source distribution tarball at some point.
  • Adjusted the <xref format=”counter”/> output for appendices.
  • Added code to remove any usage of Unicode U+2028 LINE SEPARATOR from the text output also in legacy mode.
  • Fixed a problem with the text format rendering of <xref> for an appendix.
  • Added a get_element_tags() method in BaseV3Writer, and commented out some debug code.
  • Removed a warning about missing country that would appear even if no <address> or <postal> was supplied.

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