Mathematical notation in RFCs
draft-rossi-mathinrfcs-02

Network Working Group                                           A. Rossi
Internet-Draft                              RFC Series Consulting Editor
Intended status: Informational                                M. Thomson
Expires: 26 September 2026                                              
                                                               L. Eggert
                                                           25 March 2026

                     Mathematical notation in RFCs
                       draft-rossi-mathinrfcs-02

Abstract

   This document defines policy and allows new technology for the
   representation of mathematical notation in RFCXML and relevant
   publication formats.  After implementation of this policy,
   mathematical notation in RFCXML and the HTML publication format will
   no longer be accepted in Unicode or Scalable Vector Graphics (SVGs).

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at
   https://github.com/alexisannerossi/id-mathinrfcs/edit/main/draft-
   rossi-mathinrfcs-00.md.  Status information for this document may be
   found at https://datatracker.ietf.org/doc/draft-rossi-mathinrfcs/.

   Discussion of this document takes place on the RSWG Editorial Stream
   Working Group mailing list (mailto:rswg@rfc-editor.org), which is
   archived at https://mailarchive.ietf.org/arch/browse/rswg/.

   Source for this draft and an issue tracker can be found at
   https://github.com/alexisannerossi/id-mathinrfcs.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Policy Requirements . . . . . . . . . . . . . . . . . . . . .   3
   3.  Implementation Guidance . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   This document allows new technology for the representation of
   mathematical notation in RFCXML and relevant publication formats
   defined in [RFC9720].  This document also defines policy requirements
   for the inclusion of mathematical content.  The primary motivations
   for this new policy are to improve accessibility for non-sighted
   users and to ensure consistent processing and rendering across the
   RFC series.

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   Mathematical notation in RFCs replaces existing practices for
   conveying mathematical content.  Inline ASCII and Unicode text or
   ASCII art and Scalable Vector Graphics (SVGs) can be replaced by
   native support for content that only contains math.  In HTML, native
   support can then be used in place of such crude alternatives; see
   Section 3 for more on this.  Other publication formats may use the
   best solution available for displaying math.  This document
   specifically removes support for displaying math in Unicode or SVG
   figures in the HTML publication format as these are not adequately
   accessible to all readers.

   The RFC Publication Center (RPC) is responsible for tooling and
   implementation decisions regarding this policy.  We expect the
   adoption of this policy to require changes and adaptation during
   implementation in early documents using this technology.

2.  Policy Requirements

   *  Mathematical notation should appear correctly in RFCXML, HTML and
      PDF publication formats, as well as any future publication formats
      that can support it.  The RPC will determine how to best represent
      math in the Text publication format.

   *  Mathematical notation should support both “inline” and “block”
      form.  "Inline" refers to notation that is used as part of text
      (like this x) and "block" form refers to equations that might be
      referenced in the same way that a figure is.

   *  It must be possible to reference “block” form equations from the
      text in a way that clearly distinguishes them from references to
      figures (or other elements that can be referenced, such as
      citations).  In academic writing, figures are usually referenced
      as “Fig. n” while equations are referenced as “Eq. n”.

   *  In the "block" form, equations must use the chosen math format.
      ASCII art or SVG renderings of math must not be used in any format
      except for the Text publication format, as noted.  Incidental use
      of math in figures can still use textual or SVG alternatives,
      provided that any math content is only illustrative.

   *  Major desktop and mobile browsers must be capable of natively
      rendering the mathematical notation correctly in the HTML
      publication format.

   *  The chosen implementation should allow representation of both the
      meaning and the formatting of the mathematical content.

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   *  The underlying markup of the RFCXML must embed and preserve the
      original mathematical source code.  Users should be able to
      readily extract this source representation without having to
      reverse-engineer it from the final visual renderings.

   *  Accessibility should be supported for readers of the HTML
      publication format who rely on various devices, software, and
      visual presentations (e.g. braille readers, screen readers,
      enlarging, and text formatting).  The RPC will refer to the W3C
      Accessibility Guidelines [WAI] when making decisions regarding
      accessibility.

   The RPC is authorized to make decisions about the representation of
   mathematical notation for both technical and editorial reasons in
   order to ensure that published RFCs meet the above policy and to
   provide consistency across the RFC series.  The RPC must document
   their decisions in a public place, and all changes to tooling or
   implementation decisions must be widely communicated to the RFC
   author community using mailing lists or other means.

   Any requirement to use a native math format over preexisting
   alternatives applies only when the math format is considered
   sufficiently mature.  There will be a period where the solution is
   being developed.  During this time, the solution might be incomplete
   or it might be impractical for existing documents to adapt.  The RPC
   is expected to exercise judgment on a case-by-case basis.

3.  Implementation Guidance

   The RPC is expected to solicit community input before making
   decisions and to publicly explain their reasoning.

   Documentation produced by the RPC should describe what technical and
   editorial constraints apply to the HTML publication format and CSS
   files.  That guidance should include updates to style guides to
   provide advice on how to decide when math forms are to be preferred
   over ASCII or Unicode workarounds that have been historically used in
   the series.  It is expected that native math support would be
   preferred in most cases, except for the simplest cases or to
   specifically support text renderings.

   Where possible, implementation decisions should focus on specifying
   what is disallowed, rather than attempting to specify exactly what is
   allowed.  These decisions should also consider the authoring process
   as a significant factor in implementation.

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   At the time of writing, the general view was that MathML [MATHML]
   best fit the requirements for inclusion in publication formats and
   RFC XML.  For authoring, the use of LaTeX [LaTeX] math syntax was
   considered most suitable.  The RPC is encouraged to consider these
   options seriously, unless better options become available in future.

   The RPC should periodically review and revise their practices.

4.  Security Considerations

   This document has no security considerations.

5.  IANA Considerations

   This document has no IANA actions.

6.  Acknowledgements

   This document has greatly benefited from the input of Carsten Bormann
   who provided significant input on the early draft versions of this
   document.

7.  Informative References

   [LaTeX]    "LaTeX - A document preparation system", n.d.,
              <https://www.latex-project.org/>.

   [MATHML]   Carlisle, D., Ion, P., and R. Miner, "Mathematical Markup
              Language (MathML) Version 3.0 2nd Edition",
              W3C Recommendation, 10 April 2014,
              <https://www.w3.org/TR/2014/REC-MathML3-20140410/>.

   [RFC9720]  Hoffman, P. and H. Flanagan, "RFC Formats and Versions",
              RFC 9720, DOI 10.17487/RFC9720, January 2025,
              <https://www.rfc-editor.org/rfc/rfc9720>.

   [WAI]      W3C, "W3C Accessibility Standards Overview", n.d.,
              <https://www.w3.org/WAI/standards-guidelines/>.

Authors' Addresses

   Alexis Rossi
   RFC Series Consulting Editor
   Email: rsce@rfc-editor.org

   Martin Thomson
   Email: mt@lowentropy.net

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   Lars Eggert
   Email: lars@eggert.org

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