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Internet Architecture Board (IAB)                            H. FlanaganRequest for Comments: 6949                             RFC Series EditorUpdates:2223                                                N. BrownleeCategory: Informational                   Independent Submissions EditorISSN: 2070-1721                                                 May 2013RFC Series Format Requirements and Future DevelopmentAbstract   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 updatesRFC 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; seeSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://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 toBCP 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.Brownlee & Flanagan           Informational                     [Page 1]

RFC 6949             RFC Series Format Requirements             May 2013Table of Contents1. Introduction ....................................................21.1. Terminology ................................................32. History and Goals ...............................................42.1. Issues Driving Change ......................................52.1.1. ASCII Art ...........................................52.1.2. Character Encoding ..................................62.1.3. Pagination ..........................................72.1.4. Reflowable Text .....................................82.1.5. Metadata and Tagging ................................82.2. Further Considerations .....................................92.2.1. Creation and Use of RFC-Specific Tools ..............92.2.2. Markup Language ....................................102.3. RFC Editor Goals ..........................................103. Format Requirements ............................................103.1. Original Requirements to Be Retained ......................103.2. Requirements to Be Added ..................................113.3. Requirements to Be Retired ................................124. Security Considerations ........................................135. Informative References .........................................136. Acknowledgements ...............................................131  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.Brownlee & Flanagan           Informational                     [Page 2]

RFC 6949             RFC Series Format Requirements             May 2013   This document takes a look at the current requirements for RFCs as   described inRFC 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 inSection 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 (seeSection 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)Brownlee & Flanagan           Informational                     [Page 3]

RFC 6949             RFC Series Format Requirements             May 20132.  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 inRFC 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.Brownlee & Flanagan           Informational                     [Page 4]

RFC 6949             RFC Series Format Requirements             May 2013   NeitherRFC 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 inSection 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.Brownlee & Flanagan           Informational                     [Page 5]

RFC 6949             RFC Series Format Requirements             May 2013      *  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.Brownlee & Flanagan           Informational                     [Page 6]

RFC 6949             RFC Series Format Requirements             May 2013      *  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.Brownlee & Flanagan           Informational                     [Page 7]

RFC 6949             RFC Series Format Requirements             May 2013   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 ofRFC 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.Brownlee & Flanagan           Informational                     [Page 8]

RFC 6949             RFC Series Format Requirements             May 2013   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.Brownlee & Flanagan           Informational                     [Page 9]

RFC 6949             RFC Series Format Requirements             May 20132.2.2.  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.Brownlee & Flanagan           Informational                    [Page 10]

RFC 6949             RFC Series Format Requirements             May 2013      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.Brownlee & Flanagan           Informational                    [Page 11]

RFC 6949             RFC Series Format Requirements             May 2013      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.")Brownlee & Flanagan           Informational                    [Page 12]

RFC 6949             RFC Series Format Requirements             May 2013      *  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.Brownlee & Flanagan           Informational                    [Page 13]

RFC 6949             RFC Series Format Requirements             May 2013Authors' Addresses   Heather Flanagan   RFC Series Editor   EMail: rse@rfc-editor.org   Nevil Brownlee   Independent Submissions Editor   EMail rfc-ise@rfc-editor.orgBrownlee & Flanagan           Informational                    [Page 14]