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Network Working Group                                       H. Levkowetz
Internet-Draft                                              Elf Tools AB
Intended status: Informational                             July 16, 2018
Expires: January 17, 2019


Implementation notes for RFC 7991, "The 'xml2rfc' Version 3 Vocabulary"
           draft-levkowetz-xml2rfc-v3-implementation-notes-00

Abstract

   This memo documents issues and observations found while implementing
   RFC 7991.  Individual notes are organised into separate sections,
   depending on their characters.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 17, 2019.

Copyright Notice

   Copyright (c) 2018 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
   (https://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.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Fitness for Purpose . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Degraded Table of Contents  . . . . . . . . . . . . . . .   4
     2.2.  Justification of Tables and Artwork . . . . . . . . . . .   4
     2.3.  RFC Publication Date Policy . . . . . . . . . . . . . . .   5
   3.  Issues with the Schema  . . . . . . . . . . . . . . . . . . .   5
     3.1.  RFC 7991  . . . . . . . . . . . . . . . . . . . . . . . .   5
       3.1.1.  In Section 2.5.5, "name" Attribute  . . . . . . . . .   5
       3.1.2.  In Section 2.20, <dl> . . . . . . . . . . . . . . . .   5
       3.1.3.  New Section 2.20.4, "indent" Attribute  . . . . . . .   6
       3.1.4.  In Section 2.29, <li> . . . . . . . . . . . . . . . .   6
       3.1.5.  In Section 2.32, <name> . . . . . . . . . . . . . . .   7
       3.1.6.  In Section 2.42, <references> . . . . . . . . . . . .   7
       3.1.7.  In Section 2.45.1, "category" Attribute . . . . . . .   7
       3.1.8.  In Section 2.53.3 and 2.53.4. . . . . . . . . . . . .   8
       3.1.9.  In Section 2.63.2, <ul> "empty" attribute . . . . . .   8
       3.1.10. In Section 3.4.2, "hangIndent" Attribute  . . . . . .   8
       3.1.11. In Appendix C.  Relax NG schema . . . . . . . . . . .   8
       3.1.12. Use of the term 'counter'.  . . . . . . . . . . . . .   9
     3.2.  RFC 7998  . . . . . . . . . . . . . . . . . . . . . . . .   9
       3.2.1.  In Section 5.2.6, Attribute Default Value Insertion .   9
       3.2.2.  In Section 5.4.2.1, Compare <rfc> "submissionType"
               and <seriesInfo> "stream".  . . . . . . . . . . . . .   9
       3.2.3.  In Section 5.4.6, "pn" Numbering. . . . . . . . . . .  10
   4.  Non-Schema Issues . . . . . . . . . . . . . . . . . . . . . .  10
     4.1.  RFC 7991  . . . . . . . . . . . . . . . . . . . . . . . .  10
       4.1.1.  In Section 2.17, <date> . . . . . . . . . . . . . . .  10
       4.1.2.  In Section 2.47, <seriesInfo> . . . . . . . . . . . .  11
       4.1.3.  In Appendix A.1.1: TLP switch-over date discrepancies  11
       4.1.4.  Index . . . . . . . . . . . . . . . . . . . . . . . .  12
       4.1.5.  Anchors . . . . . . . . . . . . . . . . . . . . . . .  12
     4.2.  RFC 7992  . . . . . . . . . . . . . . . . . . . . . . . .  12
       4.2.1.  In Section 8.1.1, Index Contents  . . . . . . . . . .  12
     4.3.  RFC 7994  . . . . . . . . . . . . . . . . . . . . . . . .  12
       4.3.1.  Additional Guidance . . . . . . . . . . . . . . . . .  12
     4.4.  RFC 7998  . . . . . . . . . . . . . . . . . . . . . . . .  13
       4.4.1.  In Section 5.2.3, <date> Insertion  . . . . . . . . .  13
       4.4.2.  In Section 5.2.4, "prepTime" Insertion  . . . . . . .  13
       4.4.3.  In Section 5.2.6, Attribute Default Value Insertion .  13
       4.4.4.  In Section 5.2.7, "toc" Attribute . . . . . . . . . .  14
       4.4.5.  In Section 5.2.8, "removeInRFC" Warning Paragraph . .  14
       4.4.6.  In Section 5.3.1, "month" Attribute . . . . . . . . .  14
       4.4.7.  In Section 5.3.2, ASCII Attribute Processing  . . . .  14
       4.4.8.  New Section: "keepWithNext" Normalisation . . . . . .  15
       4.4.9.  In Section 5.4.2, <boilerplate> Insertion . . . . . .  15
       4.4.10. In Section 5.4.2.1, Compare <rfc> submissionType and



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               <seriesInfo> "stream".  . . . . . . . . . . . . . . .  15
       4.4.11. In Section 5.4.2.2, "Status of this Memo" Insertion .  16
       4.4.12. In Section 5.4.3, <reference> "target" Insertion  . .  16
       4.4.13. In Section 5.4.4, <name> Slugification  . . . . . . .  16
       4.4.14. In Section 5.4.6, "pn" Numbering. . . . . . . . . . .  17
       4.4.15. In Section 5.4.7, <iref> Numbering  . . . . . . . . .  18
       4.4.16. In Section 5.4.8.2, "derivedContent" Insertion
               (without Content) . . . . . . . . . . . . . . . . . .  18
       4.4.17. In Section 5.5.1, <artwork> Processing  . . . . . . .  18
       4.4.18. In Section 5.5.2, <sourcecode> Processing . . . . . .  18
       4.4.19. In Section 5.4.8.2, "derivedContent" Insertion. . . .  19
       4.4.20. In Section 5.4.9, <relref> Processing . . . . . . . .  19
       4.4.21. In Section 5.6.3,  <link> Processing  . . . . . . . .  20
       4.4.22. New Section for Index . . . . . . . . . . . . . . . .  20
   5.  Informative References  . . . . . . . . . . . . . . . . . . .  20
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   Implementation of tool support for [RFC7991] and related
   specifications has been done during 2017 and 2018, split in the
   following individual parts, all implemented as individual modes of
   the python-based xml2rfc processor [XML2RFC]:

   *  An XML converter from vocabulary version 2 [RFC7749] to version 3
      [RFC7991]

   *  A Normalisation processor, "PrepTool", [RFC7997]

   *  An XML to plain text converter [RFC7994] for the version 3
      vocabulary

   *  An XML to html converter [RFC7992] for the version 3 vocabulary
      (pending as of 08 Jul 2018)

   *  A HTML to PDF converter [RFC7995] for the version 3 vocabulary
      (pending as of 08 Jul 2018)

   During the implementation work, a number of issues with the
   specification has been found (this was expected at the outset by all
   parties) and a number of observations has been made about limitations
   of the specification and vocabulary version 3 schema, and also
   limitations in the specification of the work to be done.

   The purpose of this memo is to collect those issues and observations
   in one place.





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2.  Fitness for Purpose

   The introduction to [RFC7991] states:

      "This document defines the "xml2rfc" version 3 vocabulary: an XML-
      based language used for writing RFCs and Internet-Drafts.  It is
      heavily derived from the version 2 vocabulary that is also under
      discussion.  This document obsoletes the v2 grammar described in
      RFC 7749."

   However, an unstated assumption seems to have been that the new tools
   and formatters would be used primarily to produce HTML output, in
   order to transition to publication of renderings of RFCs in more
   modern formats than plain-text ASCII.

   This is a reasonable and worthwhile goal, but as a result, the schema
   as specified in [RFC7991] has some drawbacks compared with the
   version 2 vocabulary when used to produce Internet-Drafts in the text
   format common within the IETF (Internet Engineering Task Force) at
   this time.

2.1.  Degraded Table of Contents

   Lack of pagination has little impact on direct online readability,
   but when comparing the output of the new text formatter with the old
   one, one aspect leaps out: Since there is no pagination, the table of
   contents simply lists the section headers to a certain depth, without
   any accompanying page numbers.  This makes a surprising difference in
   how useful the table of contents is in getting an initial feel for
   the document.  The at-a-glance information which lets a reader know
   if this is a document of 10 pages or 100 is simply lacking.

   Recommendation:  Add support for pagination in a future version of
      the text formatter.

2.2.  Justification of Tables and Artwork

   The version 3 schema deprecates the previously available 'align'
   attribute for artwork and tables, and the PrepTool will remove these
   attributes if used.  This makes a previous feature that was
   appreciated by some authors unavailable.  In the text formatter, the
   effect is simply to make all tables and artwork left-aligned, which
   may not be the most readable and polished output, but for the HTML
   formatter it also potentially removes the option of letting text flow
   around smaller artwork and tables in a controlled way.

   Recommendation:  Make the 'align' attribute for artwork and tables
      available again.  (The current text formatter code already has



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      support for the 'align' attribute for these elements; but since
      the attribute is stripped away by the PrepTool, the code is never
      invoked.)

2.3.  RFC Publication Date Policy

   The specification [RFC7998] says that an error should be generated if
   a <date> specification is found with missing elements; but the RFC
   Editor publishes documents (except for April 1st RFCs) with only year
   and month, no day of month.  The specification disallows this, and in
   effect makes it impossible for the RFC Editor to publish documents
   according to the current policy regarding publication date format.

   Recommendation:  Revert to to the old behaviour, where the tool in
      RFC mode would issue a date with or without day depending on
      whether the <date> element had a day attribute or not.

3.  Issues with the Schema

3.1.  RFC 7991

3.1.1.  In Section 2.5.5, "name" Attribute

      "A filename suitable for the contents (such as for extraction to a
      local file)."

   Given the existing use of "name" on seriesInfo, this attribute name
   has a semantic dissonance.

   Recommendation:  Deprecate "name" for use on <artwork> and
      <sourcecode>, and instead use "file", which for <sourcecode> will
      be explicitly rendered, as established as best current practice
      for YANG modules (see for instance RFC 6087 [RFC6087])

3.1.2.  In Section 2.20, <dl>

   The current specification says:

      "The "hanging" attribute defines whether or not the term appears
      on the same line as the definition.  hanging="true" indicates that
      the term is to the left of the definition, while hanging="false"
      indicates that the term will be on a separate line."

   This does not match established typographic terminology.  In
   typographic terminology, "hanging indent" describes the case where
   the indentation of the second and subsequent lines of a paragraph is
   greater than the indentation of the first line.  Whether the
   definition in a definition list starts on the first line or not has



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   nothing to do with the presence of hanging indent; our definition
   lists will _always_ have hanging indent.

   The 'hanging' attribute also describes something different from what
   the term has been used to describe in the version 2 vocabulary.  This
   will be confusing to users.

   A more descriptive name for the attribute we're talking about would
   be 'start-definition-on-first-line', but that's unwieldy.  Maybe
   'newline="false"' to start the definition on the first line, or
   something like 'definition-start="first"'?

   Recommendation:  Change this to a different term that is more
      descriptive and does not use typographically incorrect
      terminology.

3.1.3.  New Section 2.20.4, "indent" Attribute

   The deprecation of the "hangIndent" attribute on <list> leaves no
   opportunity to control the size of the hanging indent.  In some
   definition lists, it is desirable to have a wide indentation, in
   order to clearly show the terms, in other cases it is more important
   to allow for a larger text volume than the width of the terms would
   allow.

   Recommendation:  Add an "indent" attribute on <dl> to control the
      size of the hanging indent.

3.1.4.  In Section 2.29, <li>

3.1.4.1.  Unordered lists with arbitrary symbols

   When <li> is used with <ul empty="true">, the rendering is under-
   specified (the specification say 'no label will be show", but doesn't
   say whether list indentation (leading white-space) should be
   eliminated or not.

   If the intention is to make it possible to render unordered lists
   with arbitrary symbols, chosen on a per-list-item basis, the current
   attributes of <li> are insufficient to indent and line-wrap list
   items properly with <ul empty='true'>.

   It is not possible, for instance, to use <ul> lists to generate XML
   for a table of content, since if the with of the bullet (the section
   number, in this case) is unknown, the proper indentation and line
   wrapping cannot be determined.





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   Recommendation:  Add an explicit "bullet" attribute to support this
      use case.

3.1.4.2.  Mixed Content Model

   The mixed content model for <li> --- either text and inline elements
   like sub, sup, bcp14, _or_ <t>, <ul>, <figure> etc, is non-intuitive
   and may be hard for users to keep straight.

   Recommendation:  Consider simplifying the schema by requiring that
      text and inline elements always are placed within a <t> element.

   This would apply also to other elements that today have alternative
   content models: <blockquote>, <dd>, <td>, and <th>.

3.1.5.  In Section 2.32, <name>

   So the <name> element can contain text or <tt>, and <tt> can contain
   other markup like <sub> and <sup> etc., but why cannot <name> contain
   <sup> etc.  directly?

3.1.6.  In Section 2.42, <references>

   The v3 schema cannot properly model multiple reference subsections
   contained within one numbered section.  The v2 formatter handled this
   by silently inserting a containing section, but with the introduction
   of the preptool, which in theory should produce a master file from
   which various formatters would produce equivalent results, this
   becomes troublesome, as the automatic insertion of a container
   section is specified for the html formatter, in section 9.8. of RFC
   7992, but not for the text formatter.  It would be much better to
   make the prepped xml explicitly show exactly what should be rendered,
   and not rely on formatters silently insert elements.

   Recommendation:  Update the schema to make it possible for
      <references> to contain <references>, and have the prepped xml
      explicitly show both the encapsulating section and the
      subsections.  The current preptool implementation does this.

3.1.7.  In Section 2.45.1, "category" Attribute

   Changing the "category" attribute of <rfc> to a name value in an
   additional <seriesInfo> makes it much harder than it needs to be to
   look it up.  It also makes the semantics of <seriesInfo> less clear.

   Recommendation:  Remove this, and keep the "category" attribute on
      <rfc>




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3.1.8.  In Section 2.53.3 and 2.53.4.

3.1.8.1.  Unnecessary limitation on where the "keepWithNext" attribute
          can be used

   Why keepWithNext only on <t>?  It would be very natural to expect to
   be able to say keepWithNext for 2 tables, or 2 figures, or 2 lists?

   Recommendation:  Permit keepWithNext on all elements that can be
      siblings to <t>.

3.1.8.2.  Violation of KISS and DRY principles

   keepWithNext on one element is equivalent with keepWithPrevious on
   the following element, provided the following element can have a
   keepWithPrevious attribute.  Providing both violates both KISS and
   DRY.

   Recommendation:  Keep only one of these two attributes, preferably
      keepWithNext.

3.1.9.  In Section 2.63.2, <ul> "empty" attribute

   In v2, this results in a list using space as the bullet, thus each
   list entry is indented as with other bullet symbols.  However, this
   leaves no way to get list entries with arbitrary text that are not
   indented, in order to produce lists such as that used in Table of
   Content and Index.

   The current implementation introduces a new attribute "bare" with the
   possible values "false" | "true" to signal this.  This works, but is
   maybe clumsier than necessary.

3.1.10.  In Section 3.4.2, "hangIndent" Attribute

      "Deprecated.  Use <dl> instead."

   This causes capability loss.  The "hangIndent" attribute not only
   signalled that hanging indent should be used, but also gave the size
   of the indent.  No equivalent control has been provided for the <dl>
   element in the version 3 vocabulary.

3.1.11.  In Appendix C.  Relax NG schema

   The "colspan" attribute is given a default value of "0", this should
   be "1".  "0" is not otherwise defined in the text, and the only
   reasonable interpretation would be to hide the cell (make it occupy
   zero columns).



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   The "rowspan" attribute is given a default value of "0", this should
   be "1".  "0" is not otherwise defined in the text, and the only
   reasonable interpretation would be to hide the cell (make it occupy
   zero rows).

3.1.12.  Use of the term 'counter'.

   The classical meaning of this term is a a monotonically increasing
   sequence of integers, globally unique or unique within a context.  In
   this document, it is instead meant to indicate section, table, figure
   numbers, which for sections are not plain counters.

   To make more interesting, in other contexts in the document, the
   notation "-nnn", which also would normally indicate a dash followed
   by digits, i.e., a counter, is also re-interpreted to include section
   numbers; strings of numbers including embedded period signs.  This is
   bad terminology.

   Recommendation:  Instead of "counter", use "number" as the attribute
      value, and explicitly say "Section number, Figure number,
      Table number or ordered list labels" in the description.  Use
      "-n.n" instead of "-nnn".

3.2.  RFC 7998

3.2.1.  In Section 5.2.6, Attribute Default Value Insertion

   The <seriesInfo> "stream" attribute has a default value of "IETF".
   The effect of setting default values after the XInclude processing is
   to set stream="IETF" on all reference <seriesInfo> which don't have a
   stream set.  This is probably not right.

   The current implementation removes the default value for the "stream"
   attribute from the schema.

3.2.2.  In Section 5.4.2.1, Compare <rfc> "submissionType" and
        <seriesInfo> "stream".

   It doesn't seem like a good fit to have tag attributes that all have
   to be set to the same value.  This is not DRY, and unnecessarily
   introduces the possibility of conflict, as a result of multiple
   <seriesInfo> elements being permitted (Relevant to the v3 schema, not
   the preptool).








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3.2.3.  In Section 5.4.6, "pn" Numbering.

   The list of elements that are given p- or paragraph tags is severely
   limited, and since the presence of a pn= attribute is required in
   order to make internal <xref> instances work, this limits the
   elements to which it is possible to reference with html fragment
   identifiers.  Why?
   Why is <dt> and <li> present, but not <ol>, <dl>, <ul>?

   The current implementation adds p- numbering to <list>, <dl>, <dd>,
   <ol>, <ul>, which all are allowed to have pn= attributes according to
   the schema.

4.  Non-Schema Issues

4.1.  RFC 7991

4.1.1.  In Section 2.17, <date>

4.1.1.1.  Current Date Requirement

      "When the prep tool is used to create Internet-Drafts, it will
      reject a submitted Internet-Draft that has a <date> element in the
      boilerplate for itself that is anything other than today."

   It is not up to the format definition to set policy for acceptance or
   rejection of draft submissions.  The matter is more complex than the
   text assumes, see for instance datatracker issue #2422.  In addition
   to being inappropriate, this text also quietly changes policy from
   +/- 3 days to +/- 0 days, without saying that it updates RFC 4228
   [RFC4228], which is the current specification of permissible dates in
   draft submissions.  Finally, enforcing this would cause _a lot_ of
   grief and problems.

   This specification item has been ignored in the implementation.

4.1.1.2.  Date Specification in References

      "Bibliographic references: In dates in <reference> elements, the
      date information can have prose text for the month or year.  For
      example, vague dates (year="ca. 2000"), date ranges
      (year="2012-2013"), non-specific months (month="Second quarter"),
      and so on are allowed."

   The text regarding prose text for month and year in bibliographic
   references is not workable.  How should month and year be combined?
   Some bibliographic references may have date text which requires year
   first, others year last, and so on.  Mixing the described fuzziness



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   into the otherwise strict year, month, date format makes little sense
   when the result of combining the year, month and date attributes
   cannot be predictably and correctly rendered.

   Recommendation:  Instead of the current specification, permit either
      that the <date> element may have text content, or an alternative
      attribute to be used for rendering if year, month, or day cannot
      be specified exactly.

4.1.2.  In Section 2.47, <seriesInfo>

   The possible and forbidden combinations of attributes for this
   element has now become so convoluted that it's really hard to
   understand how to use it correctly.  This needs a serious
   reconsideration.

   The 'name' attribute is mandatory, and only 3 values are permitted:
   "RFC", "Interned-Draft", and "DOI".  But it is also mandatory to set
   the name to "" for a <seriesInfo> with a status attribute.  Hmm...

   So there are 4, not 3 permitted values: "RFC", "Internet-Draft",
   "DOI", and "".

   This means that all reference files which has things like name="ISO",
   name="W3C Recommendation", etc., etc., have become illegal.

   This limitation on <seriesInfo> "name" attributes has not been
   enforced in the current implementation.

4.1.3.  In Appendix A.1.1: TLP switch-over date discrepancies

   There are discrepancies between the specified switch-over dates in
   the specification, and those given by the Trust statements:

   *  TLP3.0: The specification says 2009-11-01 but the TLP statement
      says effective date 2009-09-12.

   *  TLP4.0: The specification says 2010-04-01 but the TLP statement
      says effective date 2009-12-28.  The dates on which TLP 4 started
      to be use in published RFCs seems to match the stated effective
      date of 2009-12-28, based on a scan of some RFCs around that date.

   The current implementation uses the official dates in the preptool,
   not the dates in RFC 7991.

   RFC 7991 also states this about the pre5378 text: this text appears
   under "Copyright Notice", unless the document was published before
   November 2009, in which case it appears under "Status of This Memo".



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   This does not agree at all with what actual RFCs contain; they seem
   to consistently have this text under Copyright Notice.

4.1.4.  Index

   There is no guidance on the structure of an index, if one is to be
   generated by the preptool.

4.1.5.  Anchors

   Section 5.1 of RFC 7992 says in part:

      "The prep tool produces XML with anchor attributes in all elements
      that need them."

   This is rather vital information regarding the content of the prepped
   xml when building a formatter, unfortunately it is not mentioned in
   RFC 7991.

4.2.  RFC 7992

4.2.1.  In Section 8.1.1, Index Contents

   The index has an extra <div> enclosing the contents, starting
   directly after <h2>, while sections explicitly does not have a div
   here.  This irregularity seems quite unnecessary, but makes the
   formatter code more complex than need be.  Could we please align the
   two?

4.3.  RFC 7994

4.3.1.  Additional Guidance

   *  <aside>: Guidance requested on the rendering.  Now rendered with
      an indentation of 9 relative to surrounding text

   *  <blockquote>: Guidance requested on the rendering.  Now rendered
      with an indentation of 3 spaces, pipe(|), two spaces relative to
      surrounding text.

   *  <sub>: Guidance requested.  Now rendered as _(text)

   *  <sup>: Guidance requested.  Now rendered as ^(text)

   *  <tt>: Guidance requested.  Now rendered as "text"

   *  Guidance for <eref> rendering.  In the html formatter, handling of
      <eref> is straightforward and is specified; it simply translates



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      to an external link.  In the legacy text formatter, <eref> was
      handled by inserting an extra <references> subsection called
      "URLs", and adding reference entries for the URLs there, while the
      <eref> citation point got a trailing numeric reference number.
      With the preptool output becoming the authoritative published
      document, this difference won't be reflected in the xml.  The two
      formats would be more aligned if the text formatter renders <eref>
      URLs inline.

      Recommendation:  Change the rendering of <eref> in text to render
         the URL inline within parentheses instead of adding the 'URLs'
         reference subsection.

4.4.  RFC 7998

4.4.1.  In Section 5.2.3, <date> Insertion

   Error if any of year, month, day is missing:

   It is an unnecessary and unwanted restriction when not in RFC
   processing mode to given an error for missing date elements.  Missing
   date elements is permitted because they make it easier for draft
   authors to rev drafts without having to pay attention to the date
   values every time they generate new output.  This requirement should
   apply only to RFC prepping mode.

   Additionally, in RFC processing mode, this implicitly changes the
   RFC-Editor policy regarding publication dates, which earlier have
   specified only year and month (except for April 1st RFCs).  Is this
   intentional?

4.4.2.  In Section 5.2.4, "prepTime" Insertion

   This is under-specified, given the detailed requirements on the
   <date> attributes.  Should probably be RFC3339.

4.4.3.  In Section 5.2.6, Attribute Default Value Insertion

   All the default values in 7991 are also expressed in the v3.rnc
   schema.  Remove text indicating otherwise.  And by the way, it was
   very helpful to extract these from the schema programmatically;
   having them specified otherwise would make it much harder to follow a
   changing schema.

   A number of attributes which are deprecated have default values.  The
   current specification will cause those to be inserted, even if they
   have been removed earlier by the v2v3 converter because they are
   deprecated.  This seems inconsistent.



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   Recommendation:  Omit deprecated attributes from the default-setting.

4.4.4.  In Section 5.2.7, "toc" Attribute

   It's specified that sections with <boilerplate> ancestors should have
   toc="exclude", but this won't then affect <boilerplate> sections
   which are inserted as part of the processing in 5.4.2.  It would make
   more sense to move this processing to after 5.4.2.

   The logic in the second bullet is flawed.  First it says to set
   elements with children with toc="include" to "include", but then it
   says that it is an error if they are set to "exclude".  Either there
   should be a warning, and the toc= attribute should be updated, or
   there should be an error and termination.  Not both.

4.4.5.  In Section 5.2.8, "removeInRFC" Warning Paragraph

   This potentially inserts a new <t> element, but after the default
   setting in 5.2.6.  Maybe place default setting after all potential
   element insertions have taken place.

4.4.6.  In Section 5.3.1, "month" Attribute

      "Normalise the values of "month" attributes in all <date> elements
      in <front> elements in <rfc> elements to numeric values."

   Is that 'in' a direct descendant relationship, or any descendant?
   I.e., does this affect <date> elements in included <reference>
   elements?  Unclear.  (RFC7991 is much clearer on this point, but
   that's not an excuse for being unclear here).

4.4.7.  In Section 5.3.2, ASCII Attribute Processing

   The uppercasing of 'ascii' in the section <name> is incorrect in this
   case; the attribute name is explicitly 'ascii', not 'ASCII'.  The
   section name should be '"ascii" Attribute Processing'.

      "In every <author> element"...

   After the earlier XInclude processing, this will include all the
   author elements in the included references, which the document author
   cannot normally do an anything about.  Is this the intention?

   Recommendation:  Limit it to /rfc/front/author' elements.

   <title> and <postalLine> also has an ascii attribute -- is it a
   mistake that they are not mentioned here?  Assuming so, for the
   preptool implementation.



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   What about the ascii* attributes on author?  Assuming they should be
   processed the same way.

4.4.8.  New Section: "keepWithNext" Normalisation

   This should specify normalisation of keepWithNext/keepWithPrevious
   such as to replace all keepWithNext with an equivalent
   keepWithPrevious on the following <t>

4.4.9.  In Section 5.4.2, <boilerplate> Insertion

      "Create a <boilerplate> element if it does not exist.  If there
      are any children of the <boilerplate> element, produce a warning
      that says "Existing boilerplate being removed.  Other tools,
      specifically the draft submission tool, will treat this condition
      as an error" and remove the existing children."

   Should this be done in both I-D mode and RFC mode?  The trouble is
   that the following subsections only describes the boilerplate
   relevant to an RFC; there's additional boilerplate that is needed for
   drafts.  I don't think it's reasonable to have a draft with only
   parts of the boilerplate contained in a boilerplate section.

   Recommendation:  The boilerplate-element insertion parts of 5.4.2 be
      done in both RFC and draft mode, with the appropriate boilerplate
      for each case.  Add text to describe the appropriate boilerplate
      for drafts, or remove the sections specific to RFC boilerplate.

   This section also specifies an error message to be used verbatim; the
   troublesome thing is that it's not clear what it means.  The message
   is: "Existing boilerplate being removed.  Other tools, specifically
   the draft submission tool, will treat this condition as an error".
   What is it that the draft submission tool is going to treat as an
   error?  The presence of boilerplate?  Why?  The removal of
   boilerplate?  How is that related to draft submission?  This is very
   jumbled.

4.4.10.  In Section 5.4.2.1, Compare <rfc> submissionType and
         <seriesInfo> "stream".

   This comes too late.  It is specified that if either is missing, it
   should be added.  But the default attribute setting earlier has set
   stream="IETF" on all <seriesInfo> elements that didn't have it.  If a
   document is read without submissionType, and stream set correctly to
   something else than "IETF" on one of the <seriesInfo> elements, then
   the default-setting will have created a conflict which cannot be
   resolved purely from the document at this point.




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   It doesn't seem like a good fit to have tag attributes that all have
   to be set to the same value.  This is not DRY, and unnecessarily
   introduces the possibility of conflict, as a result of multiple
   <seriesInfo> elements being permitted (Relevant to the v3 schema, not
   the preptool).

   Recommendation:  Remove the default value for stream, and make it
      subordinate to submissionType.

4.4.11.  In Section 5.4.2.2, "Status of this Memo" Insertion

   It specifies that one should consider both submissionType and
   <seriesInfo> stream value; but those have just been set equal in
   5.4.2.1.  The text should be adjusted to not sound as if these two
   should be both be considered as if they could be different.

4.4.12.  In Section 5.4.3, <reference> "target" Insertion

      "Insert "target" attributes for RFC, DOI, and Internet-Draft
      references that lack them."

   It is indicated that the rfc-editor will provide the URL patterns.
   What are they?

   The order of <seriesInfo> determines the rendering order.  These
   should be sorted in the desired rendering order (currently 'BCP',
   'RFC', 'DOI'.  The current implementation does so.

4.4.13.  In Section 5.4.4, <name> Slugification

   The 'n-' prefix for slugs is unnecessarily opaque.

   Recommendation:  Use slugs with prefix "name-" rather than "n-", to
      be more self-documenting.

   Should the slugs be unique?  Assuming yes, but guidance would be
   good.  The current implementation enforces unique slugs, with the
   following algorithm:

   *  remove non-ascii letters

   *  replace-non-letters with dash, compacting multiple dashes to one

   *  reduce length to 32, but insure uniqueness by increasing length or
      adding numerical suffixes, up to length 40 with suffixes numbered
      2 to 99.





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4.4.14.  In Section 5.4.6, "pn" Numbering.

   What does 'pn' mean?  Cryptic is never good when humans have to deal
   with it.  At least explain as "part number" in text.  Possibly even
   change pn="" to part="".

   <back><section> is not mentioned.  Assuming numbering as section-
   appendix.1.2

   <iref> elements are not mentioned (but covered in 7991).  Should be
   listed in 7998.

   The numbering scheme is inconsistent between notes/boilerplate and
   other sections, in that attempting to split a pn on dashes (which
   external tools might want to do) the boilerplate/note sections
   contain an additional dash.

   Recommendation:  Change that to a dot, for better consistency with
      other sections.  This also makes the <t> part numbers less
      confusing: "section-boilerplate.1-1" instead of "section-
      boilerplate-1-1"

4.4.14.1.  RFC format anchors / fragment identifiers

   The anchor prefixes described unnecessarily break with existing links
   to document sections.  Wikipedia has (2018-02-19) about 84 000 pages
   that link to RFCs; with most pages having multiple links.  A small
   manual sampling indicates that about 1 link in 10 has a #section-
   fragment identifier.  All of these will break if the new tools are
   used to generated content linked from these pages.

   How much larger than Wikipedia is the whole of the internet, in terms
   of links to RFCs?  Hard to tell (though searching for 'rfc' on Google
   indicates 'about 10 000 000 results).  In any case, we are talking
   about breaking a substantial number of links using fragment
   identifiers of the format #section- and #appendix- if the new tools
   are used to replace the old html content that sites currently point
   to.

   Recommendation:  update rfc7998 preptool to use these prefixes,
      instead:

      -  "section-xxx"

      -  "figure-xxx"

      -  "table-xxx"




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      -  "appendix-xxx"

      -  "index-xxx"

      -  "para-xxx"

      -  "name-xxx"

4.4.15.  In Section 5.4.7, <iref> Numbering

   Numbering of <iref> talks about setting the 'pn' attribute.  Mixed
   into this is a mention of 'irefid', which isn't a valid attribute.
   The current implementation assumes that 'pn' is meant.

   The item and sub-item text is not constrained to slug format; in
   order to deliver useful pn values, slugification should be done.  On
   the other hand, the explicit prescription of how to ensure uniqueness
   clashes with the total lack of uniqueness attention under 5.4.4.

   Recommendation:  Remove the details of how to ensure uniqueness.

4.4.16.  In Section 5.4.8.2, "derivedContent" Insertion (without
         Content)

   There's a formatting mistake:

   The last sentence of the last bullet ("Issue a warning...") should
   not be part of the bullet, but a separate final paragraph for the
   Section.

4.4.17.  In Section 5.5.1, <artwork> Processing

   RFC791 specifies that the <artwork> content is a fallback if there is
   external <svn> content, but 7998 says to drop the fallback and insert
   the external <svn>.  This deletes information, and makes the fallback
   unavailable.  This needs a better handling.

   For now, if there is fallback content, the external URL content is
   converted to a data: URL for the src, which pulls it in and makes it
   immutable, but retains the fallback.

4.4.18.  In Section 5.5.2, <sourcecode> Processing

   List item 4 says:

      "fill the content of the <sourcecode> element with the resolved
      XML from the URI in the "src" attribute"




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   However, the URI should not be assumed to resolve to xml, but instead
   treated like CDATA.

4.4.19.  In Section 5.4.8.2, "derivedContent" Insertion.

   It is not clear from the description if the derived content text
   should contain square brackets when an <xref> would be rendered with
   square brackets in current output formats.

   It is not clear if the derived content should include the 'Figure',
   or 'Table' label when pointing to such objects.  When rendering such
   a reference in the current output formats, the generated text would
   include the label, but the current text seems to lean towards not
   making this part of the derived content, which would cause
   incompatibility with the output of v2 formatters.

   The purpose of this is insufficiently explained.  If the intention is
   to use this when generating derived formats, there are problems: If,
   for instance, the derived format with a <reference> target is set to
   'RFC1234', the text inserted in a derived format should have
   surrounding square brackets; but if the target is a section, it
   should not.  If on the other hand the derived format includes the
   square brackets when appropriate, the link in a derived format with
   internal link capability will use the whole of the bracketed string,
   rather than the more appropriate text within the brackets.

   The current implementation works around this by using different
   formatter code for different cases, which is not good from the
   viewpoint of using the prepped XML as the archival format.  The whole
   "derivedContent" handling and specification needs a thorough rework,
   with specification of the intended use of the attribute by
   formatters.

4.4.20.  In Section 5.4.9, <relref> Processing

   Why doesn't <relref> have the same format options as <xref>?  Surely
   they must be just as relevant here.  But more importantly, <relref>
   overlaps <xref> so much that it would be better to just add section,
   relative, and displayFormat to <xref>.  Maybe change displayFormat to
   the earlier proposed 'sectionFormat'.

   Recommendation:  Deprecate <relref>, and fold the functionality into
      <xref>.








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4.4.21.  In Section 5.6.3, <link> Processing

   Bullet 4.: Bad grammar s/RFC the form/RFC, in the form/

   Bullet 4.: Hmm.  The <link rel="convertedFrom" href="draft-....">
   should ideally be created automatically, but there is no clear path
   of how to do that.

   Recommendation:  Require docName to be set to the draft name, and use
      that to create this link.

4.4.22.  New Section for Index

   RFC7998 does not say a word about index, but it seems counter-
   intuitive not to produce one, given all other prepping being done.
   What's more, in Section 2.27 of RFC 7991 there's this text:

      "When the prep tool is creating index content, it collects the
      items in a case-sensitive fashion for both the item and sub-item
      level."

5.  Informative References

   [RFC4228]  Rousskov, A., "Requirements for an IETF Draft Submission
              Toolset", RFC 4228, DOI 10.17487/RFC4228, December 2005,
              <https://www.rfc-editor.org/info/rfc4228>.

   [RFC6087]  Bierman, A., "Guidelines for Authors and Reviewers of YANG
              Data Model Documents", RFC 6087, DOI 10.17487/RFC6087,
              January 2011, <https://www.rfc-editor.org/info/rfc6087>.

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

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

   [RFC7992]  Hildebrand, J., Ed. and P. Hoffman, "HTML Format for
              RFCs", RFC 7992, DOI 10.17487/RFC7992, December 2016,
              <https://www.rfc-editor.org/info/rfc7992>.

   [RFC7993]  Flanagan, H., "Cascading Style Sheets (CSS) Requirements
              for RFCs", RFC 7993, DOI 10.17487/RFC7993, December 2016,
              <https://www.rfc-editor.org/info/rfc7993>.





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   [RFC7994]  Flanagan, H., "Requirements for Plain-Text RFCs",
              RFC 7994, DOI 10.17487/RFC7994, December 2016,
              <https://www.rfc-editor.org/info/rfc7994>.

   [RFC7995]  Hansen, T., Ed., Masinter, L., and M. Hardy, "PDF Format
              for RFCs", RFC 7995, DOI 10.17487/RFC7995, December 2016,
              <https://www.rfc-editor.org/info/rfc7995>.

   [RFC7996]  Brownlee, N., "SVG Drawings for RFCs: SVG 1.2 RFC",
              RFC 7996, DOI 10.17487/RFC7996, December 2016,
              <https://www.rfc-editor.org/info/rfc7996>.

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

   [RFC7998]  Hoffman, P. and J. Hildebrand, ""xml2rfc" Version 3
              Preparation Tool Description", RFC 7998,
              DOI 10.17487/RFC7998, December 2016,
              <https://www.rfc-editor.org/info/rfc7998>.

   [XML2RFC]  Levkowetz, H., "xml2rfc", 2018,
              <https://pypi.org/pypi/xml2rfc>.

Author's Address

   Henrik Levkowetz
   Elf Tools AB
   Ollonstigen 8
   Sweden

   Email: henrik@levkowetz.com



















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