path: root/doc/rfc/rfc6949.txt

Internet Architecture Board (IAB)                            H. Flanagan
Request for Comments: 6949                             RFC Series Editor
Updates: 2223                                                N. Brownlee
Category: Informational                   Independent Submissions Editor
ISSN: 2070-1721                                                 May 2013


         RFC Series Format Requirements and Future Development

Abstract

   This document describes the current requirements and requests for
   enhancements for the format of the canonical version of RFCs.  Terms
   are defined to help clarify exactly which stages of document
   production are under discussion for format changes.  The requirements
   described in this document will determine what changes will be made
   to RFC format.  This document updates RFC 2223.

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 5741.

   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/rfc6949.

Copyright Notice

   Copyright (c) 2013 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.






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Table of Contents

   1. Introduction ....................................................2
      1.1. Terminology ................................................3
   2. History and Goals ...............................................4
      2.1. Issues Driving Change ......................................5
           2.1.1. ASCII Art ...........................................5
           2.1.2. Character Encoding ..................................6
           2.1.3. Pagination ..........................................7
           2.1.4. Reflowable Text .....................................8
           2.1.5. Metadata and Tagging ................................8
      2.2. Further Considerations .....................................9
           2.2.1. Creation and Use of RFC-Specific Tools ..............9
           2.2.2. Markup Language ....................................10
      2.3. RFC Editor Goals ..........................................10
   3. Format Requirements ............................................10
      3.1. Original Requirements to Be Retained ......................10
      3.2. Requirements to Be Added ..................................11
      3.3. Requirements to Be Retired ................................12
   4. Security Considerations ........................................13
   5. Informative References .........................................13
   6. Acknowledgements ...............................................13

1  Introduction

   Over 40 years ago, the RFC Series began as a collection of memos in
   an environment that included handwritten RFCs, typewritten RFCs, RFCs
   produced on mainframes with complicated layout tools, and more.  As
   the tools changed and some of the source formats became unreadable,
   the core individuals behind the Series realized that a common format
   that could be read, revised, and archived long in the future was
   required.  US-ASCII was chosen for the encoding of characters, and
   after a period of variability, a well-defined presentation format was
   settled upon.  That format has proved to be persistent and reliable
   across a large variety of devices, operating systems, and editing
   tools.  That stability has been a continuing strength of the Series.
   However, as new technology, such as small devices and advances in
   display technology, comes into common usage, there is a growing
   desire to see the format of the RFC Series adapt to take advantage of
   these different ways to communicate information.

   Since the format stabilized, authors and readers have suggested
   enhancements to the format.  However, no suggestion developed clear
   consensus in the Internet technical community.  As always, some
   individuals see no need for change, while others press strongly for
   specific enhancements.





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   This document takes a look at the current requirements for RFCs as
   described in RFC 2223 [RFC2223] and more recently in 2223bis
   [2223bis].  Section 2 reviews recent requests for enhancements as
   understood from community discussion and various proposals for new
   formats including HTML, XML, PDF, and EPUB.  The actual requirements
   are then captured in Section 3.  The focus of this document is on the
   Canonical format of RFCs, but some mention of other phases in the RFC
   publication process and the document formats associated with these
   phases is also included.  Terms are defined to help clarify exactly
   which stages of document production are under discussion for format
   changes.

1.1  Terminology

   ASCII: Coded Character Set -- 7-bit American Standard Code for
   Information Interchange, ANSI X3.4-1986 [ASCII]

   Canonical format: the authorized, recognized, accepted, and archived
   version of the document
      *  Currently: formatted plain text

   Metadata: information associated with a document so as to provide,
   for example, definitions of its structure, or of elements within the
   document such as its topic or author

   Publication format: display and distribution format as it may be read
   or printed after the publication process has completed
      *  Currently published by the RFC Editor: formatted plain text,
         PDF of the formatted plain text, PDF that contains figures
         (rare)
      *  Currently made available by other sites: HTML, PDF, others

   Reflowable text: text that automatically wraps to the next line in a
   document as the user moves the margins of the text, either by
   resizing the window or changing the font size

   Revisable format: the format that will provide the information for
   conversion into a Publication format; it is used or created by the
   RFC Editor (see Section 2.3 for an explanation of current practice)
      *  Currently: XML (optional), nroff (required)

   Submission format: the format submitted to the RFC Editor for
   editorial revision and publication
      * Currently: formatted plain text (required), XML (optional),
         nroff (optional)






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2.  History and Goals

   Below are the current RFC format rules as defined in [RFC2223] and
   clarified in 2223bis.

      *  The character codes are ASCII.

      *  Each page must be limited to 58 lines followed by a form feed
         on a line by
            itself.

      *  Each line must be limited to 72 characters followed by carriage
         return and line feed.

      *  No overstriking (or underlining) is allowed.

      *  These "height" and "width" constraints include any headers,
         footers, page numbers, or left-side indenting.

      *  Do not fill the text with extra spaces to provide a straight
         right margin.

      *  Do not do hyphenation of words at the right margin.

      *  Do not use footnotes.  If such notes are necessary, put them at
         the end of a section, or at the end of the document.

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

      *  Note that the number of pages in a document and the page
         numbers on which various sections fall will likely change with
         reformatting.  Thus, cross-references in the text by section
         number usually are easier to keep consistent than cross-
         references by page number.

      *  RFCs in plain ASCII text may be submitted to the RFC Editor in
         e-mail messages (or as online files) in either the finished
         Publication format or in nroff.  If you plan to submit a
         document in nroff please consult the RFC Editor first.

   The precedent for additional formats, specifically PostScript, is
   described in RFC 2223 and has been used for a small number of RFCs:

      Note that since the ASCII text version of the RFC is the primary
      version, the PostScript version must match the text version.  The
      RFC Editor must decide if the PostScript version is "the same as"
      the ASCII version before the PostScript version can be published.



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   Neither RFC 2223 nor 2223bis uses the term 'metadata', though the RFC
   Editor currently refers to components of the text such as the Stream,
   Status (e.g., Updates, Obsoletes), Category, and ISSN as 'metadata'.

2.1.  Issues Driving Change

   While some authors and readers of RFCs report that they find the
   strict limits of character encoding, line limits, and so on to be
   acceptable, others claim to find those limitations a significant
   obstacle to their desire to communicate and read the information via
   an RFC.  With a broader community of authors currently producing RFCs
   and a wider range of presentation devices in use, the issues being
   reported by the community indicate limitations of the current
   Canonical format that must be reviewed and potentially addressed in
   the Canonical RFC format.

   While the specific points of concern vary, the main issues discussed
   are:

      *  ASCII art

      *  Character encoding

      *  Pagination

      *  Reflowable text

      *  Metadata

   Each area of concern has people in favor of change and people opposed
   to it, all with reasonable concerns and requirements.  Below is a
   summary of the arguments for and against each major issue.  These
   points are not part of the list of requirements; they are the inputs
   that informed the requirements discussed in Section 3 of this
   document.

2.1.1.  ASCII Art

   Arguments in favor of limiting all diagrams, equations, tables, and
   charts to ASCII art depictions only include:

      *  Dependence on advanced diagrams (or any diagrams) causes
         accessibility issues.

      *  Requiring ASCII art results in people often relying more on
         clear written descriptions rather than just the diagram itself.





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      *  Use of the ASCII character set forces design of diagrams that
         are simple and concise.

   Arguments in favor of allowing the use of more complex diagrams in
   place of the current use of ASCII art include:

      *  State diagrams with multiple arrows in different directions and
         labels on the lines will be more understandable.

      *  Protocol flow diagrams in which each step needs multiple lines
         of description will be clearer.

      *  Scenario descriptions that involve three or more parties with
         communication flows between them will be clearer.

      *  Given the difficulties in expressing complex equations with
         common mathematical notation, allowing graphic art would allow
         equations to be displayed properly.

      *  Complex art could allow for grayscale or color to be introduced
         into the diagrams.

   Two suggestions have been proposed regarding how graphics should be
   included: one that would have graphic art referenced as a separate
   document to the Publication format, and one that would allow embedded
   graphics in the Publication format.

2.1.2.  Character Encoding

   For most of the history of the RFC Series, the character encoding for
   RFCs has been ASCII.  Below are arguments for keeping ASCII as well
   as arguments for expanding to UTF-8.

   Arguments for retaining the ASCII-only requirement:

      *  It is the most easy to search and display across a variety of
         platforms.

      *  In extreme cases of having to retype or scan hard copies of
         documents (it has been required in the past), ASCII is
         significantly easier to work with for rescanning and retaining
         all of the original information.  There can be no loss of
         descriptive metadata such as keywords or content tags.








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      *  If we expand beyond ASCII, it will be difficult to know where
         to draw the line on which characters are and are not allowed.
         There will be issues with dependencies on local file systems
         and processors being configured to recognize any other
         character set.

      *  The IETF works in ASCII (and English).  The Internet research,
         design, and development communities function almost entirely in
         English.  That strongly suggests that an ASCII document can be
         properly rendered and read by everyone in the communities and
         audiences of interest.

   Arguments for expanding to allow UTF-8:

      *  In discussions of internationalization, actually being able to
         illustrate the issue is rather helpful, and you can't
         illustrate a Unicode code point with "U+nnnn".

      *  It will provide the ability to denote protocol examples using
         the character sets those examples support.

      *  It will allow better support for international character sets,
         in particular, allowing authors to spell their names in their
         native character sets.

      *  Certain special characters in equations or quoted from other
         texts could be allowed.

      *  Citations of web pages using more international characters are
         possible.

   Arguments for strictly prescribed UTF-8 use:

      *  In order to keep documents as searchable as possible, ASCII-
         only should be required for the main text of the document, and
         some broader UTF-8 character set allowed under clearly
         prescribed circumstances (e.g., author names and references).

2.1.3.  Pagination

   Arguments for continuing the use of discrete pages within RFCs:

      *  Ease of reference and printing; referring to section numbers is
         too coarse a method.







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   Arguments for removing the pagination requirement:

      *  Removing pagination will allow for a smoother reading
         experience on a wider variety of devices, platforms, and
         browsers.

      *  Removing pagination results in people often using subsections
         rather than page number for reference purposes, forcing what
         would otherwise be long sections to be broken into subsections.
         This would encourage documents that are better organized and
         simpler.

2.1.4.  Reflowable Text

   Arguments against requiring text to be reflowable:

      *  Reflowable text may impact the usability of graphics and tables
         within a document.

   Arguments for requiring text to be reflowable:

      *  RFCs are more readable on a wider variety of devices and
         platforms, including mobile devices and assorted screen
         layouts.

2.1.5.  Metadata and Tagging

   While metadata requirements are not part of RFC 2223, there is a
   request that descriptive metadata tags be added as part of a revision
   of the Canonical RFC format.  These tags would allow for enhanced
   content by embedding information such as links, tags, or quick
   translations and could help control the look and feel of the
   Publication format.  While the lack of metadata in the current RFCs
   does not impact an RFC's accessibility or readability, several
   individuals have indicated that allowing metadata within the RFCs
   would make their reading of the documents more efficient.

   Arguments for allowing metadata in the Canonical and Publication
   formats:

      *  Metadata potentially allows readers to get more detail out of a
         document.  For example, if non-ASCII characters are allowed in
         the Author's Address and Reference sections, metadata must
         include translations of that information.







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   Arguments against metadata in the final Canonical and Publication
   formats:

      *  Metadata adds additional overhead to the overall process of
         creating RFCs and may complicate future usability as a result
         of requiring backward compatibility for metadata tags.

2.2.  Further Considerations

   Some of the discussion beyond the issues described above went into a
   review of potential solutions.  Those solutions and the debate around
   them added a few more points to the list of potential requirements
   for a change in RFC Format.  In particular, the discussion of tools
   introduced the idea of whether a change in format should also include
   the creation and ongoing support of specific RFC authoring and/or
   rendering tools and whether the Canonical format should be a format
   that must go through a rendering agent to be readable.

2.2.1.  Creation and Use of RFC-Specific Tools

   Arguments in support of community-supported RFC-specific tools:

      *  Given the community that would be creating and supporting these
         tools, there would be greater control and flexibility over the
         tools and how they implement the RFC format requirements.

      *  Community-supported tools currently exist and are in extensive
         use within the community, so it would be most efficient to
         build on that base.

   Arguments against community-supported RFC-specific tools:

      *  We cannot be so unique in our needs that we can't use
         commercial tools.

      *  Ongoing support for these tools adds a greater level of
         instability to the ongoing availability of the RFC Series
         through the decades.

      *  The community that would support these tools cannot be relied
         on to be as stable and persistent as the Series itself.










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2.2.2.  Markup Language

   Arguments in support of a markup language as the Revisable format:

      *  Having a markup language such as XML or HTML allows for greater
         flexibility in creating a variety of Publication formats, with
         a greater likelihood of similarity between them.

   Arguments against a markup language as the Revisable format:

      *  Having the Revisable format be in a markup language instead of
         in a simple text-formatting structure ties us in to specific
         tools and/or tool support going forward.

2.3.  RFC Editor Goals

   Currently, each RFC has an nroff file created prior to publication.
   For RFCs revised using an XML file, the nroff file is created by
   converting XML to nroff at the final step.  As more documents are
   submitted with an XML file (of the RFCs published in 2012,
   approximately 65% were submitted with an XML file), this conversion
   is problematic in terms of time spent and data lost from XML.  Making
   the publication process for the RFC Editor more efficient is strongly
   desired.

3.  Format Requirements

   Understanding the major pain points and balancing them with the
   expectation of long-term viability of the documents brings us to a
   review of what must be kept of the original requirements, what new
   requirements may be added, and what requirements may be retired.
   Detailed rules regarding how these changes will be implemented will
   be documented in a future RFC.

3.1.  Original Requirements to Be Retained

   Several components of the original format requirements must be
   retained to ensure the ongoing continuity, reliability, and
   readability of the Series:

      1.  The content of an RFC must not change, regardless of format,
          once published.

      2.  The Canonical format must be persistent and reliable across a
          large variety of devices, operating systems, and editing tools
          for the indefinite future.  This means the format must be both
          readable and editable across commonly used devices, operating
          systems, and platforms for the foreseeable future.



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      3.  While several Publication formats must be allowed, in order to
          continue support for the most basic reading and search tools
          and to provide continuity for the Series, at least one
          Publication format must be plain text.

      4.  The boilerplate and overall structure of the RFC must be in
          accordance with current RFC and Style Guide requirements (see
          [RFC5741]).

   Issues such as overstriking, page justification, hyphenation, and
   spacing will be defined in the RFC Style Guide [Style].

3.2.  Requirements to Be Added

   In addition to those continuing requirements, discussions with
   various members of the wider Internet community have yielded the
   following general requirements for the RFC Series.

      5.  The documents must be made accessible to people with visual
          disabilities through such means as including alternative text
          for images and limiting the use of color.  See the W3C's
          accessibility documents [WCAG20] and the United Nations
          "Convention on the Rights of Persons with Disabilities"
          [UN2006] for guidance.  Appropriate authoring tools are highly
          desirable but focus on the creation of Internet-Drafts, a
          topic outside the scope of the RFC Editor.

      6.  The official language of the RFC Series is English.  ASCII is
          required for all text that must be read to understand or
          implement the technology described in the RFC.  Use of non-
          ASCII characters, expressed in a standard Unicode Encoding
          Form (such as UTF-8), must receive explicit approval from the
          document stream manager and will be allowed after the rules
          for the common use cases are defined in the Style Guide.

      7.  The Submission and Publication formats need to permit
          extending the set of metadata tags, for the addition of
          labeled metadata.  A predefined set of metadata tags must be
          created to make use of metadata tags consistent for the life
          of the Series.

      8.  Graphics may include ASCII art and a more complex form to be
          defined, such as SVG line art [SVG].  Color and grayscale will
          not be accepted.  RFCs must correctly display in monochromatic
          black-and-white to allow for monochrome displays, black-and-
          white printing, and support for visual disabilities.





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      9.  The Canonical format must be renderable into self-contained
          Publication formats in order to be easily downloaded and read
          offline.

      10. Fixed-width fonts and non-reflowable text are required for
          ASCII-art sections, source code examples, and other places
          where strict alignment is required.

      11. At least one Publication format must support readable print to
          standard paper sizes.

      12. The Canonical format should be structured to enable easy
          program identification and parsing of code or specifications,
          such as MIB modules and ABNF.

   The requirements of the RFC Editor regarding RFC format and the
   publication process include:

      13. The final conversion of all submitted documents to nroff
          should be replaced by using an accepted Revisable format
          throughout the process.

      14. In order to maintain an efficient publication process, the RFC
          Editor must work with the minimal number of files required for
          each submission (not a tar ball of several discrete
          components).

      15. In order to maintain the focus of the RFC Editor on editing
          for clarity and consistency rather than document layout
          details, the number of Publication formats produced by the RFC
          editor must be limited.

      16. Tools must support error checking against document layout
          issues as well as other format details (diagrams, line breaks,
          variable- and fixed-width fonts).

3.3.  Requirements to Be Retired

   Some of the original requirements will be removed from consideration,
   but detailed rules regarding how these changes will be implemented
   will be documented in a future RFC.

      *  Pagination ("Each page must be limited to 58 lines followed by
         a form feed on a line by itself.")

      *  Maximum line length ("Each line must be limited to 72
         characters followed by carriage return and line feed.")




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      *  Limitation to 100% ASCII text ("The character codes are
         ASCII.")

4.  Security Considerations

   This document sets out requirements for RFCs in their various
   formats; it does not concern interactions between Internet hosts.
   Therefore, it does not have any specific security considerations.

5.  Informative References

   [RFC2223]  Postel, J. and J. Reynolds, "Instructions to RFC Authors",
              RFC 2223, October 1997.

   [RFC5741]  Daigle, L., Ed., Kolkman, O., Ed., and IAB, "RFC Streams,
              Headers, and Boilerplates", RFC 5741, December 2009.

   [ASCII]    American National Standard for Information Systems - Coded
              Character Sets - 7-Bit American National Standard Code for
              Information Interchange (7-Bit ASCII), ANSI X3.4-1986,
              American National Standards Institute, Inc., March 26,
              1986.

   [2223bis]  Reynolds, J. and R. Braden, "Instructions to Request for
              Comments (RFC) Authors", Work in Progress, August 2004.

   [Style]    Flanagan, H. and S. Ginoza, "RFC Style Guide", Work in
              Progress, October 2012.

   [SVG]      Dahlstrom, E., Dengler, P., Grasso, A., Lilley, C.,
              McCormack, C., Schepers, D., and J. Watt, "Scalable Vector
              Graphics (SVG) 1.1 (Second Edition)", W3C Recommendation,
              16 August 2011, <http://www.w3.org/TR/SVG11/>.

   [WCAG20]   Caldwell, B., Cooper, M., Reid, L., and G. Vanderheiden,
              "Web Content Accessibility Guidelines (WCAG) 2.0", 11
              December 2008, <http://www.w3.org/TR/WCAG20/>.

   [UN2006]   United Nations, "Convention on the Rights of Persons with
              Disabilities", December 2006.

6.  Acknowledgements

   The authors received a great deal of helpful input from the community
   in pulling together these requirements and wish to particularly
   acknowledge the help of Joe Hildebrand, Paul Hoffman, and John
   Klensin, who each published an Internet-Draft on the topic of
   potential format options before the IETF 84 BOF.



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Authors' Addresses

   Heather Flanagan
   RFC Series Editor

   EMail: rse@rfc-editor.org


   Nevil Brownlee
   Independent Submissions Editor

   EMail rfc-ise@rfc-editor.org







































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