Requirements for Plain-Text RFCs

Internet Architecture Board (IAB)                            H. Flanagan
Request for Comments: 7994                                    RFC Editor
Category: Informational                                    December 2016
ISSN: 2070-1721


                    Requirements for Plain-Text RFCs

Abstract

   In 2013, after a great deal of community discussion, the decision was
   made to shift from the plain-text, ASCII-only canonical format for
   RFCs to XML as the canonical format with more human-readable formats
   rendered from that XML.  The high-level requirements that informed
   this change were defined in RFC 6949, "RFC Series Format Requirements
   and Future Development".  Plain text remains an important format for
   many in the IETF community, and it will be one of the publication
   formats rendered from the XML.  This document outlines the rendering
   requirements for the plain-text RFC publication format.  These
   requirements do not apply to plain-text RFCs published before the
   format transition.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Architecture Board (IAB)
   and represents information that the IAB has deemed valuable to
   provide for permanent record.  It represents the consensus of the
   Internet Architecture Board (IAB).  Documents approved for
   publication by the IAB are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7994.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Table of Contents

   1. Introduction ....................................................2
   2. Character Encoding ..............................................4
   3. Figures and Artwork .............................................4
   4. General Page Format Layout ......................................4
      4.1. Headers and Footers ........................................5
      4.2. Table of Contents ..........................................5
      4.3. Line Width .................................................5
      4.4. Line Spacing ...............................................5
      4.5. Hyphenation ................................................5
   5. Elements from the xml2rfc v3 Vocabulary .........................5
   6. Security Considerations .........................................6
   7. References ......................................................6
      7.1. Normative References .......................................6
      7.2. Informative References .....................................7
   IAB Members at the Time of Approval ................................8
   Acknowledgements ...................................................8
   Author's Address ...................................................8

1.  Introduction

   In 2013, after a great deal of community discussion, the decision was
   made to shift from the plain-text, ASCII-only canonical format for
   RFCs to XML as the canonical format [XML-ANNOUNCE].  The high-level
   requirements that informed this change were defined in [RFC6949],
   "RFC Series Format Requirements and Future Development".  Plain text
   remains an important format for many in the IETF community, and it
   will be one of the publication formats rendered from the XML.  This
   document outlines the rendering requirements for the plain-text RFC
   publication format.  These requirements do not apply to plain-text
   RFCs published before the format transition.

   The Unicode Consortium defines "plain text" as "Computer-encoded text
   that consists only of a sequence of code points from a given
   standard, with no other formatting or structural information.

   Plain-text interchange is commonly used between computer systems that
   do not share higher-level protocols." [UNICODE-GLOSSARY].  In other
   words, plain-text files cannot include embedded character formatting
   or style information.  The actual character encoding, however, is not
   limited to any particular sequence of code points.

   A plain-text output for RFCs will continue to be required for the
   foreseeable future.  The process of converting xml2rfc version 2
   (xml2rfc v2) into text documents is well understood [RFC7749].  We
   plan to rely on the practice to date to inform the requirements for
   converting xml2rfc version 3 (xml2rfc v3) to text [RFC7991].  This
   document calls out those requirements that are changed from v2 or
   otherwise deserve special attention, such as the requirements around
   the character encoding that may be used; changes in the page layout;
   and changes in how figures, artwork, and pagination may be handled.
   For more details on general style, see "RFC Style Guide" [RFC7322].

   The following assumptions drive the changes in the plain-text output
   for RFCs:

   o  The existing tools used by the RFC Editor and many members of the
      author community to create the text file are complicated to change
      and support; manual manipulation is often required for the final
      output.  In particular, handling page breaks and associated widows
      and orphans for paginated output is tricky [WIDOWS].

   o  Additional publication formats -- for example, PDF, HTML -- will
      be available that will offer features such as markup and pretty
      printing.

   o  There is an extensive tool chain in existence among the community
      to work with plain-text documents.  Similar functionality may be
      possible with other publication formats, but the workflow that
      uses the existing tool chain should be supported as much as is
      considered practical.

   Where practical, the original guidance for the structure of a
   plain-text RFC has been kept (e.g., with line lengths, with lines
   per page [INS2AUTH]).  Other publication formats, such as HTML and
   PDF, will include additional features that will not be present in the
   plain text (e.g., paragraph numbering, typographical emphasis).

   The details described in this document are expected to change based
   on experience gained in implementing the new publication toolsets.
   Revised documents will be published capturing those changes as the
   toolsets are completed.  Other implementers must not expect those
   changes to remain backwards-compatible with the details described in
   this document.

2.  Character Encoding

   Plain-text files for RFCs will use the UTF-8 [RFC3629] character
   encoding.  That said, the use of non-ASCII characters will be only
   allowed in a limited and controlled fashion.

   Many elements within the xml2rfc v3 vocabulary have an attribute for
   the ASCII equivalent to a non-ASCII character string.  The ASCII
   equivalent will be rendered within the plain text as per the guidance
   in "The Use of Non-ASCII Characters in RFCs" [RFC7997]; please view
   the PDF version of that document.

   The plain-text file will include a Byte Order Mark (BOM) to provide
   text reader software with in-band information about the character
   encoding scheme used.

3.  Figures and Artwork

   Artwork, such as network diagrams or performance graphs, must be
   tagged by the XML <artwork> element (see Section 2.5 of "The
   'xml2rfc' Version 3 Vocabulary" [RFC7991].  Where this artwork is
   comprised of an ASCII art diagram, it must be tagged as
   "type='ascii-art'".  The plain-text format will only include
   ASCII art.  If the canonical format includes figures or artwork other
   than ASCII art, then the plain-text output must include a pointer to
   the relevant figure in the HTML version of the RFC to allow readers
   to see the relevant artwork.

   Authors who wish to include ASCII art for the plain-text file and
   SVG art for the other outputs may do so, but they should be aware of
   the potential for confusion to individuals reading the RFC with two
   unique diagrams describing the same content.  If there is conflicting
   information between the publication formats, please review the XML
   and PDF files to resolve the conflict.

4.  General Page Format Layout

   One plain-text output will be created during the publication process
   with basic pagination that includes a form feed instruction every
   58 lines at most, including blank lines.  Instructions or a script
   will be made available by and for the community to strip out
   pagination as per individual preference.

4.1.  Headers and Footers

   The front matter on the front page (such as the RFC number and
   category) and the back matter on the last page (the authors' full
   names and contact information) will continue with the structure
   described in RFC 7841 [RFC7841], "RFC Streams, Headers, and
   Boilerplates".  Running headers and footers will no longer be added.

4.2.  Table of Contents

   In order to retain similar content wherever possible between the
   various publication formats, the table of contents will list section
   and subsection numbers and titles but will not include page numbers.

4.3.  Line Width

   Each line must be limited to 72 characters followed by the character
   sequence that denotes an end-of-line (EOL).  The EOL sequence used by
   the RFC Editor will be the two-character sequence CR LF (Carriage
   Return followed by Line Feed).  This limit includes any left-side
   indentation.

   Note that the EOL used by the RFC Editor may change with different
   transports and as displayed in different display software.

4.4.  Line Spacing

   Use single-spaced text within a paragraph, and one blank line between
   paragraphs.

4.5.  Hyphenation

   Hyphenated words (e.g., "Internet-Draft") should not be split across
   successive lines.

5.  Elements from the xml2rfc v3 Vocabulary

   The plain-text formatter uses the relevant tags from the xml2rfc v3
   source file to build a document conforming to the layout and
   structure described by the full RFC Style Guide [RFC7322] (including
   the updates in the web portion of the Style Guide) [STYLEWEB].

6.  Security Considerations

   The requirements of the plain-text format involve no significant
   security considerations.  As part of the larger format project,
   however, unintended changes to the text as a result of the
   transformation from the base XML file could in turn corrupt a
   standard, practice, or critical piece of information about a
   protocol.

7.  References

7.1.  Normative References

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of
              ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629,
              November 2003, <http://www.rfc-editor.org/info/rfc3629>.

   [RFC6949]  Flanagan, H. and N. Brownlee, "RFC Series Format
              Requirements and Future Development", RFC 6949,
              DOI 10.17487/RFC6949, May 2013,
              <http://www.rfc-editor.org/info/rfc6949>.

   [RFC7322]  Flanagan, H. and S. Ginoza, "RFC Style Guide", RFC 7322,
              DOI 10.17487/RFC7322, September 2014,
              <http://www.rfc-editor.org/info/rfc7322>.

   [RFC7749]  Reschke, J., "The "xml2rfc" Version 2 Vocabulary",
              RFC 7749, DOI 10.17487/RFC7749, February 2016,
              <http://www.rfc-editor.org/info/rfc7749>.

   [RFC7841]  Halpern, J., Ed., Daigle, L., Ed., and O. Kolkman, Ed.,
              "RFC Streams, Headers, and Boilerplates", RFC 7841,
              DOI 10.17487/RFC7841, May 2016,
              <http://www.rfc-editor.org/info/rfc7841>.

   [RFC7991]  Hoffman, P., "The "xml2rfc" Version 3 Vocabulary",
              RFC 7991, DOI 10.17487/RFC7991, December 2016,
              <http://www.rfc-editor.org/info/rfc7991>.

   [RFC7997]  Flanagan, H., Ed., "The Use of Non-ASCII Characters in
              RFCs", RFC 7997, DOI 10.17487/RFC7997, December 2016,
              <http://www.rfc-editor.org/info/rfc7997>.

7.2.  Informative References

   [INS2AUTH] RFC Editor, "Instructions to Request for Comments (RFC)
              Authors", August 2004, <https://www.rfc-editor.org/
              materials/instructions2authors.txt>.

   [STYLEWEB] RFC Editor, "Web Portion of the Style Guide",
              February 2016,
              <http://www.rfc-editor.org/styleguide/part2/>.

   [UNICODE-GLOSSARY]
              The Unicode Consortium, "Glossary of Unicode Terms",
              September 2016, <http://www.unicode.org/glossary/>.

   [WIDOWS]   Wikipedia, "Widows and orphans", September 2016,
              <https://en.wikipedia.org/w/
              index.php?title=Widows_and_orphans&oldid=738356204>.

   [XML-ANNOUNCE]
              Flanagan, H., "Subject: Direction of the RFC Format
              Development effort", May 2013,
              <http://www.rfc-editor.org/pipermail/
              rfc-interest/2013-May/005584.html>.

IAB Members at the Time of Approval

   The IAB members at the time this memo was approved were
   (in alphabetical order):

      Jari Arkko
      Ralph Droms
      Ted Hardie
      Joe Hildebrand
      Russ Housley
      Lee Howard
      Erik Nordmark
      Robert Sparks
      Andrew Sullivan
      Dave Thaler
      Martin Thomson
      Brian Trammell
      Suzanne Woolf

Acknowledgements

   This document owes a great deal of thanks to the efforts of the RFC
   Format Design Team: Nevil Brownlee, Tony Hansen, Joe Hildebrand, Paul
   Hoffman, Ted Lemon, Julian Reschke, Adam Roach, Alice Russo, Robert
   Sparks, and David Thaler.

Author's Address

   Heather Flanagan
   RFC Editor

   Email: rse@rfc-editor.org
   URI:   http://orcid.org/0000-0002-2647-2220