path: root/docs/dev/todo.txt

======================
 Docutils_ To Do List
======================

:Author: David Goodger (with input from many); open to all Docutils
         developers
:Contact: goodger@python.org
:Date: $Date$
:Revision: $Revision$
:Copyright: This document has been placed in the public domain.

.. _Docutils: http://docutils.sourceforge.net/

.. contents::


Priority items are marked with "@" symbols.  The more @s, the higher
the priority.  Items in question form (containing "?") are ideas which
require more thought and debate; they are potential to-do's.

Many of these items are awaiting champions.  If you see something
you'd like to tackle, please do!  If there's something you'd like to
see done but are unable to implement it yourself, `please consider
contributing`__ in other ways.

__ http://docutils.sf.net/#please-contribute


Priorities
==========

* Always high priority: `FIX BUGS!`__

  __ ../../BUGS.html

* Include substitution files for character entities, produced by the
  tools/unicode2rstsubs.py.  As static data, these files could go
  inside the docutils package somewhere.

* A Python Source Reader component (Python auto-documentation) will be
  added.  See the document `"Plan for Enthought API Documentation
  Tool"`__ for details.  If you'd like to help, let me know!

  __ enthought-plan.html

* `Nested inline markup`_.


General
=======

* Refactor

  - Rename methods & variables according to the `Python coding
    conventions <policies.html#python-coding-conventions>`_.

  - The name-to-id conversion and hyperlink resolution code needs to be
    checked for correctness and refactored.  I'm afraid it's a bit of
    a spaghetti mess now.

* Configuration file handling needs discussion:

  - There should be some error checking on the contents of config
    files.  How much checking should be done?  How loudly should
    Docutils complain if it encounters an error/problem?

  - Docutils doesn't complain when it doesn't find a configuration
    file supplied with the ``--config`` option.  Should it?  (If yes,
    error or warning?)

  - Is a system-wide configuration file (in ``/etc/docutils.conf``) a
    good idea?

  - Is a user-specific configuration file (``~/.docutils``) really
    necessary?  Maybe the name (``.docutils``) needs discussion, too.

* Language modules: in accented languages it may be useful to have
  both accented and unaccented entries in the ``bibliographic_fields``
  mapping for versatility.

* Add a "--strict-language" option & setting: no English fallback for
  language-dependent features.

* Add internationalization to _`footer boilerplate text` (resulting
  from "--generator", "--source-link", and "--date" etc.), allowing
  translations.

* Need a Unicode to HTML entities codec for HTML writer?  No, the
  "xmlcharrefreplace" output error handler is sufficient.
  Make it the default for HTML & XML writers?

* Add validation?  See http://pytrex.sourceforge.net, RELAX NG, pyRXP.

* Ask Python-dev for opinions (GvR for a pronouncement) on special
  variables (__author__, __version__, etc.): convenience vs. namespace
  pollution.  Ask opinions on whether or not Docutils should recognize
  & use them.

* In ``docutils.readers.get_reader_class`` (& ``parsers`` &
  ``writers`` too), should we be importing "standalone" or
  "docutils.readers.standalone"?  (This would avoid importing
  top-level modules if the module name is not in docutils/readers.
  Potential nastiness.)

* @@@ Perhaps store a _`name-to-id mapping file`?  This could be
  stored permanently, read by subsequent processing runs, and updated
  with new entries.  ("Persistent ID mapping"?)

* Perhaps the ``Component.supports`` method should deal with
  individual features ("meta" etc.) instead of formats ("html" etc.)?

* Add _`object numbering and object references` (tables & figures).
  These would be the equivalent of DocBook's "formal" elements.

  We may need _`persistent sequences`, such as chapter numbers.  See
  `OpenOffice.org XML`_ "fields".  Should the sequences be automatic
  or manual (user-specifyable)?

  We need to name the objects:

  - "name" option for the "figure" directive? ::

        .. figure:: image.png
           :name: image's name

    Same for the "table" directive::

        .. table:: optional title here
           :name: table's name

           =====  =====
             x    not x
           =====  =====
           True   False
           False  True
           =====  =====

    This would also allow other options to be set, like border
    styles.  The same technique could be used for other objects.

    A preliminary "table" directive has been implemented, supporting
    table titles.  Perhaps the name should derive from the title.

  - The object could also be done this way::

        .. _figure name:

        .. figure:: image.png

    This may be a more general solution, equally applicable to tables.
    However, explicit naming using an option seems simpler to users.

  - Perhaps the figure name could be incorporated into the figure
    definition, as an optional inline target part of the directive
    argument::

        .. figure:: _`figure name` image.png

    Maybe with a delimiter::

        .. figure:: _`figure name`: image.png

    Or some other, simpler syntax.

  We'll also need syntax for object references.  See `OpenOffice.org
  XML`_ "reference fields":

  - Parameterized substitutions?  For example::

        See |figure (figure name)| on |page (figure name)|.

        .. |figure (name)| figure-ref:: (name)
        .. |page (name)| page-ref:: (name)

    The result would be::

        See figure 3.11 on page 157.

    But this would require substitution directives to be processed at
    reference-time, not at definition-time as they are now.  Or,
    perhaps the directives could just leave ``pending`` elements
    behind, and the transforms do the work?  How to pass the data
    through?  Too complicated.

  - An interpreted text approach is simpler and better::

        See :figure:`figure name` on :page:`figure name`.

    The "figure" and "page" roles could generate appropriate
    boilerplate text.  The position of the role (prefix or suffix)
    could also be utilized.

    See `Interpreted Text`_ below.

  - We could leave the boilerplate text up to the document::

        See Figure :fig:`figure name` on page :pg:`figure name`.

  - Reference boilerplate could be specified in the document
    (defaulting to nothing)::

        .. fignum::
           :prefix-ref: "Figure "
           :prefix-caption: "Fig. "
           :suffix-caption: :

  .. _OpenOffice.org XML: http://xml.openoffice.org/

* Think about _`large documents` made up of multiple subdocument
  files.  Issues: continuity (`persistent sequences`_ above),
  cross-references (`name-to-id mapping file`_ above and `targets in
  other documents`_ below).

  When writing a book, the author probably wants to split it up into
  files, perhaps one per chapter (but perhaps even more detailed).
  However, we'd like to be able to have references from one chapter to
  another, and have continuous numbering (pages and chapters, as
  applicable).  Of course, none of this is implemented yet.  There has
  been some thought put into some aspects; see `the "include"
  directive`__ and the `Reference Merging`_ transform below.

  When I was working with SGML in Japan, we had a system where there
  was a top-level coordinating file, book.sgml, which contained the
  top-level structure of a book: the <book> element, containing the
  book <title> and empty component elements (<preface>, <chapter>,
  <appendix>, etc.), each with filename attributes pointing to the
  actual source for the component.  Something like this::

      <book id="bk01">
      <title>Title of the Book</title>
      <preface inrefid="pr01"></preface>
      <chapter inrefid="ch01"></chapter>
      <chapter inrefid="ch02"></chapter>
      <chapter inrefid="ch03"></chapter>
      <appendix inrefid="ap01"></appendix>
      </book>

  (The "inrefid" attribute stood for "insertion reference ID".)

  The processing system would process each component separately, but
  it would recognize and use the book file to coordinate chapter and
  page numbering, and keep a persistent ID to (title, page number)
  mapping database for cross-references.  Docutils could use a similar
  system for large-scale, multipart documents.

  __ ../ref/rst/directives.html#including-an-external-document-fragment

  Aahz's idea:

      First the ToC::

          .. ToC-list::
              Introduction.txt
              Objects.txt
              Data.txt
              Control.txt

      Then a sample use::

          .. include:: ToC.txt

          As I said earlier in chapter :chapter:`Objects.txt`, the
          reference count gets increased every time a binding is made.

      Which produces::

          As I said earlier in chapter 2, the
          reference count gets increased every time a binding is made.

      The ToC in this form doesn't even need to be references to actual
      reST documents; I'm simply doing it that way for a minimum of
      future-proofing, in case I do want to add the ability to pick up
      references within external chapters.

  Perhaps, instead of ToC (which would overload the "contents"
  directive concept already in use), we could use "manifest".  A
  "manifest" directive might associate local reference names with
  files::

      .. manifest::
         intro: Introduction.txt
         objects: Objects.txt
         data: Data.txt
         control: Control.txt

  Then the sample becomes::

      .. include:: manifest.txt

      As I said earlier in chapter :chapter:`objects`, the
      reference count gets increased every time a binding is made.

* Add testing for Docutils' front end tools?

* Changes to sandbox/davidg/infrastructure/docutils-update?

  - Modify the script to only update the snapshots if files have
    actually changed in CVS (saving some SourceForge server cycles).

  - Make passing the test suite a prerequisite to snapshot update,
    but only if the process is completely automatic.

  - Rewrite in Python?

* Publisher: "Ordinary setup" shouldn't requre specific ordering; at
  the very least, there ought to be error checking higher up in the
  call chain.  [Aahz]

  ``Publisher.get_settings`` requires that all components be set up
  before it's called.  Perhaps the I/O *objects* shouldn't be set, but
  I/O *classes*.  Then options are set up (``.set_options``), and
  ``Publisher.set_io`` (or equivalent code) is called with source &
  destination paths, creating the I/O objects.

  Perhaps I/O objects shouldn't be instantiated until required.  For
  split output, the Writer may be called multiple times, once for each
  doctree, and each doctree should have a separate Output object (with
  a different path).  Is the "Builder" pattern applicable here?

* Perhaps I/O objects should become full-fledged components (i.e.
  subclasses of ``docutils.Component``, as are Readers, Parsers, and
  Writers now), and thus have associated option/setting specs and
  transforms.

* Multiple file I/O suggestion from Michael Hudson: use a file-like
  object or something you can iterate over to get file-like objects.

* Add an "--input-language" option & setting?  Specify a different
  language module for input (bibliographic fields, directives) than
  for output.  The "--language" option would set both input & output
  languages.

* Auto-generate reference tables for language-dependent features?
  Could be generated from the source modules.  A special command-line
  option could be added to Docutils front ends to do this.  (Idea from
  Engelbert Gruber.)

* Change the "class" attribute of elements (set with
  Element.set_class) to a list?

* Enable feedback of some kind from internal decisions, such as
  reporting the successful input encoding.  Modify runtime settings?
  System message?  Simple stderr output?

* Rationalize Writer settings (HTML/LaTeX/PEP) -- share settings.

* The "docutils.conf" included with Docutils should become complete,
  with examples of every setting (many/most commented out).  It's
  currently sparse, requiring doc lookups.

* Merge docs/user/latex.txt info into tools.txt and config.txt.

* Add an "--include file" command-line option (config setting too?),
  equivalent to ".. include:: file" as the first line of the doc text?
  Especially useful for character entity sets, text transform specs,
  boilerplate, etc.

* Parameterize the Reporter object or class?  See the `2004-02-18
  "rest checking and source path"`_ thread.

  .. _2004-02-18 "rest checking and source path":
     http://thread.gmane.org/gmane.text.docutils.user/1112

* Add a "disable_transforms" setting?  And a dummy Writer subclass
  that does nothing when its .write() method is called?  Would allow
  for easy syntax checking.  See the `2004-02-18 "rest checking and
  source path"`_ thread.

* Add a generic meta-stylesheet mechanism?  An external file could
  associate style names ("class" attributes) with specific elements.
  Could be generalized to arbitrary output attributes; useful for HTML
  & XMLs.  Aahz implemented something like this in
  sandbox/aahz/Effective/EffMap.py.

* William Dode suggested that table cells be assigned "class"
  attributes by columns, so that stylesheets can affect text
  alignment.  Unfortunately, there doesn't seem to be a way (in HTML
  at least) to leverage the "colspec" elements (HTML "col" tags) by
  adding classes to them.  The resulting HTML is very verbose::

      <td class="col1">111</td>
      <td class="col2">222</td>
      ...

  At the very least, it should be an option.  People who don't use it
  shouldn't be penalized by increases in their HTML file sizes.

  Table rows could also be assigned classes (like odd/even).  That
  would be easier to implement.

  How should it be implemented?

  * There could be writer options (column classes & row classes) with
    standard values.

  * The table directive could grow some options.  Something like
    ":cell-classes: col1 col2 col3" (either must match the number of
    columns, or repeat to fill?)  and ":row-classes: odd even" (repeat
    to fill; body rows only, or header rows too?).

  Probably per-table directive options are best.  The "class" values
  could be used by any writer, and applying such classes to all tables
  in a document with writer options is too broad.

* Make the csv-table directive work with Python 2.1/2.2.  (See the
  discussion_ on the mailing list.)

  .. _discussion: http://thread.gmane.org/gmane.text.docutils.user/1319

* The docutils.nodes.Element APIs could use some simplification.  For
  example, ``node[x]`` is ambiguous (different results if x is a
  string or an integer).  Replace with ``node[int]`` and
  ``node.attributes[string]``?

* Add file-specific settings support to config files, like::

      [file index.txt]
      compact-lists: no

  Is this even possible?  Should the criterion be the name of the
  input file or the output file?

* The "validator" support added to OptionParser is very similar to
  "traits_" in SciPy_.  Perhaps something could be done with them?
  (Had I known about traits when I was implementing docutils.frontend,
  I may have used them instead of rolling my own.)

  .. _traits: http://old.scipy.org/site_content/traits
  .. _SciPy: http://www.scipy.org/

* tools/buildhtml.py: Extend the --prune option ("prune" config
  setting) to accept file names (generic path) in addition to
  directories (e.g. --prune=docs/user/rst/cheatsheet.txt, which should
  *not* be converted to HTML).

* stylesheet & stylesheet_path settings: either one should set the
  other one to ``None`` as a side effect.  See discussion on
  docutils-develop from 2004-07-03.


Documentation
=============

User Docs
---------

* Add a FAQ entry about using Docutils (with reStructuredText) on a
  server and that it's terribly slow.  See the first paragraphs in
  <http://article.gmane.org/gmane.text.docutils.user/1584>.


Developer Docs
--------------

* Complete `Docutils Runtime Settings <../api/runtime-settings.html>`_.

* @@@ Improve the internal module documentation (docstrings in the
  code).  Specific deficiencies listed below.

  - docutils.parsers.rst.states.State.build_table: data structure
    required (including StringList).

  - docutils.parsers.rst.states: more complete documentation of parser
    internals.

* docs/ref/doctree.txt: DTD element structural relationships,
  semantics, and attributes.  In progress; element descriptions to be
  completed.

* Document the ``pending`` elements, how they're generated and what
  they do.

* Document the transforms (perhaps in docstrings?): how they're used,
  what they do, dependencies & order considerations.

* Document the HTML classes used by html4css1.py.

* Write an overview of the Docutils architecture, as an introduction
  for developers.  What connects to what, why, and how.  Either update
  PEP 258 (see PEPs_ below) or as a separate doc.

* Give information about unit tests.  Maybe as a howto?

* Document the docutils.nodes APIs.

* Complete the docs/api/publisher.txt docs.


How-Tos
-------

* Creating Docutils Writers

* Creating Docutils Readers

* Creating Docutils Transforms

* Creating Docutils Parsers

* Using Docutils as a Library


PEPs
----

* Complete PEP 258 Docutils Design Specification.

  - Fill in the blanks in API details.

  - Specify the nodes.py internal data structure implementation?

        [Tibs:] Eventually we need to have direct documentation in
        there on how it all hangs together - the DTD is not enough
        (indeed, is it still meant to be correct?  [Yes, it is.
        --DG]).

* Rework PEP 257, separating style from spec from tools, wrt Docutils?
  See Doc-SIG from 2001-06-19/20.


Python Source Reader
====================

General:

* Analyze Tony Ibbs' PySource code.

* Analyze Doug Hellmann's HappyDoc project.

* Investigate how POD handles literate programming.

* Take the best ideas and integrate them into Docutils.

Miscellaneous ideas:

* If we can detect that a comment block begins with ``##``, a la
  JavaDoc, it might be useful to indicate interspersed section headers
  & explanatory text in a module.  For example::

      """Module docstring."""

      ##
      # Constants
      # =========

      a = 1
      b = 2

      ##
      # Exception Classes
      # =================

      class MyException(Exception): pass

      # etc.

* Should standalone strings also become (module/class) docstrings?
  Under what conditions?  We want to prevent arbitrary strings from
  becomming docstrings of prior attribute assignments etc.  Assume
  that there must be no blank lines between attributes and attribute
  docstrings?  (Use lineno of NEWLINE token.)

  Triple-quotes are sometimes used for multi-line comments (such as
  commenting out blocks of code).  How to reconcile?

* HappyDoc's idea of using comment blocks when there's no docstring
  may be useful to get around the conflict between `additional
  docstrings`_ and ``from __future__ import`` for module docstrings.
  A module could begin like this::

      #!/usr/bin/env python
      # :Author: Me
      # :Copyright: whatever

      """This is the public module docstring (``__doc__``)."""

      # More docs, in comments.
      # All comments at the beginning of a module could be
      # accumulated as docstrings.
      # We can't have another docstring here, because of the
      # ``__future__`` statement.

      from __future__ import division

  Using the JavaDoc convention of a doc-comment block beginning with
  ``##`` is useful though.  It allows doc-comments and implementation
  comments.

  .. _additional docstrings:
     ../peps/pep-0258.html#additional-docstrings

* HappyDoc uses an initial comment block to set "parser configuration
  values".  Do the same thing for Docutils, to set runtime settings on
  a per-module basis?  I.e.::

      # Docutils:setting=value

  Could be used to turn on/off function parameter comment recognition
  & other marginal features.  Could be used as a general mechanism to
  augment config files and command-line options (but which takes
  precedence?).

* Multi-file output should be divisible at arbitrary level.

* Support all forms of ``import`` statements:

  - ``import module``: listed as "module"
  - ``import module as alias``: "alias (module)"
  - ``from module import identifier``: "identifier (from module)"
  - ``from module import identifier as alias``: "alias (identifier
    from module)"
  - ``from module import *``: "all identifiers (``*``) from module"

* Have links to colorized Python source files from API docs?  And
  vice-versa: backlinks from the colorized source files to the API
  docs!

* In summaries, use the first *sentence* of a docstring if the first
  line is not followed by a blank line.


reStructuredText Parser
=======================

Also see the `... Or Not To Do?`__ list.

__ rst/alternatives.html#or-not-to-do

* Add (functional) tests for the "raw" role, its class attribute, and
  the other roles as well.

* Allow the _`:trim:` option for all directives when they occur in a
  substitution definition, not only the unicode_ directive.

  .. _unicode:
     http://docutils.sf.net/docs/ref/rst/directives.html#unicode-character-codes
  
* The parser doesn't know anything about double-width characters such
  as Chinese hanza & Japanese kanji/kana.  Also, it's dependent on
  whitespace and punctuation as markup delimiters, which may not be
  applicable in these languages.

  Python 2.4 introduces the function ``unicodedata.east_asian_width``,
  so this problem will be resolved later, when Python 2.4 is in a
  reasonably stable state and being used more widely.

* Clean up the code; refactor as required.

* Add motivation sections for constructs in spec.

* Document title should grow an implicit target.

* Allow very long titles (on two or more lines)?

* And for the sake of completeness, should definition list terms be
  allowed to be very long (two or more lines) also?

* Support generic hyperlink references to _`targets in other
  documents`?  Not in an HTML-centric way, though (it's trivial to say
  ``http://www.example.com/doc#name``, and useless in non-HTML
  contexts).  XLink/XPointer?  ``.. baseref::``?  See Doc-SIG
  2001-08-10.

* .. _adaptable file extensions:

  In target URLs, it would be useful to not explicitly specify the
  file extension.  If we're generating HTML, then ".html" is
  appropriate; if PDF, then ".pdf"; etc.  How about using ".*" to
  indicate "choose the most appropriate filename extension?  For
  example::

      .. _Another Document: another.*

  Should the choice be from among existing files only?  Documents
  only, or objects (images, etc.) also?  (How to differentiate?
  Element context [within "image"]?)

  This may not be just a parser issue though; it may need framework
  support.

  Mailing list thread: `Images in both HTML and LaTeX`__

  __ http://thread.gmane.org/gmane.text.docutils.user/1239

* Implement the header row separator modification to table.el.  (Wrote
  to Takaaki Ota & the table.el mailing list on 2001-08-12, suggesting
  support for "=====" header rows.  On 2001-08-17 he replied, saying
  he'd put it on his to-do list, but "don't hold your breath".)

* Tony says inline markup rule 7 could do with a *little* more
  exposition in the spec, to make clear what is going on for people
  with head colds.

* @@ Fix the parser's indentation handling to conform with the
  stricter definition in the spec.  (Explicit markup blocks should be
  strict or forgiving?)

* @@ Tighten up the spec for indentation of "constructs using complex
  markers": field lists and option lists?  Bodies may begin on the
  same line as the marker or on a subsequent line (with blank lines
  optional).  Require that for bodies beginning on the same line as
  the marker, all lines be in strict alignment.  Currently, this is
  acceptable::

      :Field-name-of-medium-length: Field body beginning on the same
          line as the field name.

  This proposal would make the above example illegal, instead
  requiring strict alignment.  A field body may either begin on the
  same line::

      :Field-name-of-medium-length: Field body beginning on the same
                                    line as the field name.

  Or it may begin on a subsequent line::

      :Field-name-of-medium-length:
          Field body beginning on a line subsequent to that of the
          field name.

  This would be especially relevant in degenerate cases like this::

      :Number-of-African-swallows-requried-to-carry-a-coconut:
          It would be very difficult to align the field body with
          the left edge of the first line if it began on the same
          line as the field name.

* Allow for variant styles by interpreting _`indented lists` as if
  they weren't indented?  For example, currently the list below will
  be parsed as a list within a block quote::

      paragraph

        * list item 1
        * list item 2

  But a lot of people seem to write that way, and HTML browsers make
  it look as if that's the way it should be.  The parser could check
  the contents of block quotes, and if they contain only a single
  list, remove the block quote wrapper.  There would be two problems:

  1. What if we actually *do* want a list inside a block quote?

  2. What if such a list comes immediately after an indented
     construct, such as a literal block?

  Both could be solved using empty comments (problem 2 already exists
  for a block quote after a literal block).  But that's a hack.

  Perhaps a runtime setting, allowing or disabling this convenience,
  would be appropriate.  But that raises issues too:

      User A, who writes lists indented (and their config file is set
      up to allow it), sends a file to user B, who doesn't (and their
      config file disables indented lists).  The result of processing
      by the two users will be different.

  It may seem minor, but it adds ambiguity to the parser, which is
  bad.

  See the `Doc-SIG discussion starting 2001-04-18`__ with Ed Loper's
  "Structuring: a summary; and an attempt at EBNF", item 4 (and
  follow-ups, here__ and here__).  Also `docutils-users,
  2003-02-17`__ and `beginning 2003-08-04`__.

  __ http://mail.python.org/pipermail/doc-sig/2001-April/001776.html
  __ http://mail.python.org/pipermail/doc-sig/2001-April/001789.html
  __ http://mail.python.org/pipermail/doc-sig/2001-April/001793.html
  __ http://sourceforge.net/mailarchive/message.php?msg_id=3838913
  __ http://sf.net/mailarchive/forum.php?thread_id=2957175&forum_id=11444

* Make the parser modular.  Allow syntax constructs to be added or
  disabled at run-time.  Or is subclassing enough?

* Continue to report (info, level 1) enumerated lists whose start
  value is not ordinal-1?

* Generalize the "doctest block" construct (which is overly
  Python-centric) to other interactive sessions?  "Doctest block"
  could be renamed to "I/O block" or "interactive block", and each of
  these could also be recognized as such by the parser:

  - Shell sessions::

        $ cat example1.txt
        A block beginning with a "$ " prompt is interpreted as a shell
        session interactive block.  As with Doctest blocks, the
        interactive block ends with the first blank line, and wouldn't
        have to be indented.

  - Root shell sessions::

        # cat example2.txt
        A block beginning with a "# " prompt is interpreted as a root
        shell session (the user is or has to be logged in as root)
        interactive block.  Again, the block ends with a blank line.

  Other standard (and unambiguous) interactive session prompts could
  easily be added (such as "> " for WinDOS).

  Tony Ibbs spoke out against this idea (2002-06-14 Doc-SIG thread
  "docutils feedback").

* Should the "doctest" element go away, and the construct simply be a
  front-end to generic literal blocks?

* Add support for pragma (syntax-altering) directives.

  Some pragma directives could be local-scope unless explicitly
  specified as global/pragma using ":global:" options.

* Remove leading numbers from section titles for implicit link names?
  A section titled "3. Conclusion" could then be referred to by
  "``Conclusion_``" (i.e., without the "3.").

* Implement auto-enumerated lists?  See `Auto-Enumerated Lists`__.

  __ rst/alternatives.html#auto-enumerated-lists

* Support whitespace in angle-bracketed standalone URLs according to
  Appendix E ("Recommendations for Delimiting URI in Context") of `RFC
  2396`_.

  .. _RFC 2396: http://www.rfc-editor.org/rfc/rfc2396.txt

* Use the vertical spacing of the source text to determine the
  corresponding vertical spacing of the output?

* [From Mark Nodine]  For cells in simple tables that comprise a
  single line, the justification can be inferred according to the
  following rules:

  1. If the text begins at the leftmost column of the cell,
     then left justification, ELSE
  2. If the text begins at the rightmost column of the cell,
     then right justification, ELSE
  3. Center justification.

  The onus is on the author to make the text unambiguous by adding
  blank columns as necessary.  There should be a parser setting to
  turn off justification-recognition (normally on would be fine).

  Decimal justification?

* Make enumerated list parsing more strict, so that this would parse
  as a paragraph with an info message::

      1. line one
      3. line two

* Generalize the "target-notes" directive into a command-line option
  somehow?  See docutils-develop 2003-02-13.

* Include the _`character entity substitution definition files`
  `temporarily stored here <http://docutils.sf.net/tmp/charents/>`__,
  perhaps in a ``docutils/parsers/rst/includes/`` directory.  See
  `misc.include`_ below.

* Should ^L (or something else in reST) be defined to mean
  force/suggest page breaks in whatever output we have?

  A "break" or "page-break" directive would be easy to add.  A new
  doctree element would be required though (perhaps "break").  The
  final behavior would be up to the Writer.  The directive argument
  could be one of page/column/recto/verso for added flexibility.

  Currently ^L (Python's "\f") characters are treated as whitespace.
  They're converted to single spaces, actually, as are vertical tabs
  (^K, Python's "\v").  It would be possible to recognize form feeds
  as markup, but it requires some thought and discussion first.  Are
  there any downsides?  Many editing environments do not allow the
  insertion of control characters.  Will it cause any harm?  It would
  be useful as a shorthand for the directive.

  It's common practice to use ^L before Emacs "Local Variables"
  lists::

      ^L
      ..
         Local Variables:
         mode: indented-text
         indent-tabs-mode: nil
         sentence-end-double-space: t
         fill-column: 70
         End:

  These are already present in many PEPs and Docutils project
  documents.  From the Emacs manual (info):

      A "local variables list" goes near the end of the file, in the
      last page.  (It is often best to put it on a page by itself.)

  It would be unfortunate if this construct caused a final blank page
  to be generated (for those Writers that recognize the page breaks).
  We'll have to add a transform that looks for a "break" plus zero or
  more comments at the end of a document, and removes them.

* Could the "break" concept above be extended to inline forms?
  E.g. "^L" in the middle of a sentence could cause a line break.
  Only recognize it at the end of a line (i.e., "\f\n")?

  Or is formfeed inappropriate?  Perhaps vertical tab ("\v"), but even
  that's a stretch.  Can't use carriage returns, since they're
  commonly used for line endings.

* Allow a "::"-only paragraph (first line, actually) to introduce a
  literal block without a blank line?  (Idea from Paul Moore.) ::

      ::
          This is a literal block

  Is indentation enough to make the separation between a paragraph
  which contains just a ``::`` and the literal text unambiguous?
  There's one problem with this concession.  What if one wants a
  definition list item which defines the term "::"?  We'd have to
  escape it.  Currenty, "\::" doesn't work (although it should;
  **bug**), and ":\:" is misinterpreted as a field name (name "\";
  also a **bug**).  Assuming these bugs are squashed, I suppose it's a
  useful special case.  It would only be reasonable to apply it to
  "::"-only paragraphs though.  I think the blank line is visually
  necessary if there's text before the "::"::

      The text in this paragraph needs separation
      from the literal block following::
          This doesn't look right.

  Another idea.  Would it be worthwhile to allow literal blocks to
  begin without a newline after the "::"?  Example::

      ::  while True:
              print 'hello world'

  Perhaps.  Perhaps not.

* Add new syntax for _`nested inline markup`?  Or extend the parser to
  parse nested inline markup somehow?  See the `collected notes
  <rst/alternatives.html#nested-inline-markup>`__.

* Drop the backticks from embedded URIs with omitted reference text?
  Should the angle brackets be kept in the output or not? ::

      <file_name>_

  Probably not worth the trouble.

* Add ``^superscript^`` inline markup?  The only common non-markup
  uses of "^" I can think of are as short hand for "superscript"
  itself and for describing control characters ("^C to cancel").  The
  former supports the proposed syntax, and it could be argued that the
  latter ought to be literal text anyhow (e.g. "``^C`` to cancel").

* Add _`math markup`.  We should try for a general solution, that's
  applicable to any output format.  Using a standard, such as MathML_,
  would be best.  TeX (or itex_) would be acceptable as a *front-end*
  to MathML.  See `the culmination of a relevant discussion
  <http://article.gmane.org/gmane.text.docutils.user/118>`__.

  Both a directive and an interpreted text role will be necessary (for
  each markup).  Directive example::

      .. itex::
         \alpha_t(i) = P(O_1, O_2, \dots O_t, q_t = S_i \lambda)

  The same thing inline::

      The equation in question is :itex:`\alpha_t(i) = P(O_1, O_2,
      \dots O_t, q_t = S_i \lambda)`.

  .. _MathML: http://www.w3.org/TR/MathML2/
  .. _itex: http://pear.math.pitt.edu/mathzilla/itex2mmlItex.html

* How about a syntax for alternative hyperlink behavior, such as "open
  in a new window" (as in HTML's ``<a target="_blank">``)?  Double
  angle brackets might work for inline targets::

      The `reference docs <<url>>`__ may be handy.

  But what about explicit targets?

  The MoinMoin wiki uses a caret ("^") at the beginning of the URL
  ("^" is not a legal URI character).  That could work for both inline
  and explicit targets::

      The `reference docs <^url>`__ may be handy.

      .. _name: ^url

* Add an option to allow arbitrary URI schemes (not just those in
  urischemes.py)?  This would make text like "signal:noise" into a
  URI.

* Add an option to add URI schemes at runtime.

* _`Segmented lists`::

      : segment : segment : segment
      : segment : segment : very long
        segment
      : segment : segment : segment

  The initial colon (":") can be thought of as a type of bullet

  We could even have segment titles::

      :: title  : title   : title
      : segment : segment : segment
      : segment : segment : segment

  This would correspond well to DocBook's SegmentedList.  Output could
  be tabular or "name: value" pairs, as described in DocBook's docs.

* Allow backslash-escaped colons in field names::

      :Case Study\: Event Handling: This chapter will be dropped.

* _`footnote spaces`:

  When supplying the command line options
  --footnote-references=brackets and --use-latex-footnotes with the
  LaTeX writer (which might very well happen when using configuration
  files), the spaces in front of footnote references aren't trimmed.

* Enable _`tables inside XML comments`, where "--" ends comments.  I
  see three implementation possibilities:

  1. Make the table syntax characters into "table" directive options.
     This is the most flexible but most difficult, and we probably
     don't need that much flexibility.

  2. Substitute "~" for "-" with a specialized directive option
     (e.g. ":tildes:").

  3. Make the standard table syntax recognize "~" as well as "-", even
     without a directive option.  Individual tables would have to be
     internally consistent.

  Directive options are preferable to configuration settings, because
  tables are document-specific.  A pragma directive would be another
  approach, to set the syntax once for a whole document.


Directives
----------

Directives below are often referred to as "module.directive", the
directive function.  The "module." is not part of the directive name
when used in a document.

* Allow directives to be added at run-time?

* Use the language module for directive option names?

* Add "substitution_only" and "substitution_ok" function attributes,
  and automate context checking?

* Change directive functions to directive classes?  Superclass'
  ``__init__()`` could handle all the bookkeeping.

* Implement options on existing directives:

  - Add a "name" option to directives, to set an author-supplied
    identifier?

  - All directives that produce titled elements should grow implicit
    reference names based on the titles.

  - _`images.image`: "border"?

    _`Units of measure`?  (See `docutils-users, 2003-03-02
    <http://article.gmane.org/gmane.text.docutils.user/154>`__, and
    `docutils-develop, 2004-04-29
    <http://article.gmane.org/gmane.text.docutils.devel/1439>`_.)

  - _`images.figure`: "title" and "number", to indicate a formal
    figure?

  - _`parts.sectnum`: "local"?, "start", "refnum"

    A "local" option could enable numbering for sections from a
    certain point down, and sections in the rest of the document are
    not numbered.  For example, a reference section of a manual might
    be numbered, but not the rest.  OTOH, an all-or-nothing approach
    would probably be enough.

    The "start" option will specify the sequence set to use at the
    same time as the starting value, for the first part of the section
    number (i.e., section, not subsection).  For example::

        .. sectnum: :start: 1

        .. sectnum: :start: A

        .. sectnum: :start: 5

        .. sectnum: :start: I

    The first one is the default: start at 1, numbered.  The second
    one specifies letters, and start at "A".  The third specifies
    numbers, start at 5.  The last example could signal Roman
    numerals, although I don't know if they'd be applicable here.
    Enumerated lists already do all this; perhaps that code could be
    reused.

    Here comes the tricky part.  The "sectnum" directive should be
    usable multiple times in a single document.  For example, in a
    long document with "chapter" and "appendix" sections, there could
    be a second "sectnum" before the first appendix, changing the
    sequence used (from 1,2,3... to A,B,C...).  This is where the
    "local" concept comes in.  This part of the implementation can be
    left for later.

    A "refnum" option (better name?) would insert reference names
    (targets) consisting of the reference number.  Then a URL could be
    of the form ``http://host/document.html#2.5`` (or "2-5"?).  Allow
    internal references by number?  Allow name-based *and*
    number-based ids at the same time, or only one or the other (which
    would the table of contents use)?  Usage issue: altering the
    section structure of a document could render hyperlinks invalid.

  - _`parts.contents`: Add a "suppress" or "prune" option?  It would
    suppress contents display for sections in a branch from that point
    down.  Or a new directive, like "prune-contents"?

    Add an option to include topics in the TOC?  Another for sidebars?
    See docutils-develop 2003-01-29.

  - _`misc.include`:

    - @@@ Allow whitespace in paths (just not at line boundaries).

    - "encoding" option?  Take default from runtime settings.  Use
      Input component to read it in?

    - Option to select a range of lines?

    - Option to label lines?

    - Default directory for "built-in includes", using the C syntax
      ``#include <name>``?

          Use C-preprocessor semantics for locating include files?
          E.g., ``.. include:: file.txt`` will read another file into
          the current one, relative to the current file's directory,
          and ``.. include:: <standard>`` will read a standard include
          file from ``docutils/include/``.  (Should "quotes" be
          required around non-standard include files?)

          -- http://sf.net/mailarchive/message.php?msg_id=1938401

      I now think that ``docutils/parsers/rst/include/`` is a better
      place for these files, since they're reStructuredText-specific.

      Keeping standard data files together with the package code makes
      sense to me.  It seems much less complex to implement than a
      separate system data directory, such as ``/usr/share/docutils``.
      Any reason a system data directory should be used?  How does
      Distutils handle data files?

      How about an environment variable, say RSTINCLUDEPATH or
      RSTPATH?  This could be combined with a setting/option to allow
      user-defined include directories.

      For a specific application, see the discussion of `character
      entity substitution definition files`_ above.

      Instead of C-include "<syntax>", perhaps a new "include-sys"
      directive?

  - _`misc.raw`: "encoding" option?

  - _`misc.class`: @@@ Allow multiple classes (whitespace-separated)
    to be declared.

* Implement directives.  Each of the list items below begins with an
  identifier of the form, "module_name.directive_function_name".  The
  directive name itself could be the same as the
  directive_function_name, or it could differ.

  - _`html.imagemap` (Useful outside of HTML?  If not, replace with
    image only in non-HTML writers?)

  - _`parts.endnotes` (or "footnotes"): See `Footnote & Citation Gathering`_.

  - _`parts.citations`: See `Footnote & Citation Gathering`_.

  - _`misc.exec`: Execute Python code & insert the results.  Perhaps
    dangerous?  Call it "python" to allow for other languages?

  - _`misc.system`?: Execute an ``os.system()`` call, and insert the
    results (possibly as a literal block).  Definitely dangerous!  How
    to make it safe?  Perhaps such processing  should be left outside
    of the document, in the user's production system (a makefile or a
    script or whatever).  Or, the directive could be disabled by
    default and only enabled with an explicit command-line option or
    config file setting.  Even then, an interactive prompt may be
    useful, such as:

        The file.txt document you are processing contains a "system"
        directive requesting that the ``sudo rm -rf /`` command be
        executed.  Allow it to execute?  (y/N)

  - _`misc.eval`: Evaluate an expression & insert the text.  At parse
    time or at substitution time?  Dangerous?  Perhaps limit to canned
    macros; see text.date_ below.

  - _`misc.encoding`: Specify the character encoding of the input
    data.  But there are problems:

    - When it sees the directive, the parser will already have read
      the input data, and encoding determination will already have
      been done.

    - If a file with an "encoding" directive is edited and saved with
      a different encoding, the directive may cause data corruption.

  - _`misc.language`: Specify the language of a document.  There is a
    problem similar to the first problem listed for misc.encoding_,
    although to a lesser degree.

  - _`misc.settings`: Set any Docutils runtime setting from within a
    document?

  - _`misc.charents`: Equivalent to::

        .. include:: {includepath}/charents.txt

  - .. _conditional directives:

    Docutils already has the ability to say "use this content for
    Writer X" (via the "raw" directive), but it doesn't have the
    ability to say "use this content for any Writer other than X".  It
    wouldn't be difficult to add this ability though.

    My first idea would be to add a set of conditional directives.
    Let's call them "writer-is" and "writer-is-not" for discussion
    purposes (don't worry about implemention details).  We might
    have::

         .. writer-is:: text-only

            ::

                +----------+
                |   SNMP   |
                +----------+
                |   UDP    |
                +----------+
                |    IP    |
                +----------+
                | Ethernet |
                +----------+

         .. writer-is:: pdf

            .. figure:: protocol_stack.eps

         .. writer-is-not:: text-only pdf

            .. figure:: protocol_stack.png

    This could be an interface to the Filter transform
    (docutils.transforms.components.Filter).

    The ideas in `adaptable file extensions`_ above may also be
    applicable here.

    Here's an example of a directive that could produce multiple
    outputs (*both* raw troff pass-through *and* a GIF, for example)
    and allow the Writer to select. ::

        .. eqn::

           .EQ
           delim %%
           .EN
           %sum from i=o to inf c sup i~=~lim from {m -> inf}
           sum from i=0 to m sup i%
           .EQ
           delim off
           .EN

  - _`body.qa` (directive a.k.a. "faq", "questions"): Questions &
    Answers.  Implement as a generic two-column marked list?  As a
    standalone (non-directive) construct?  (Is the markup ambiguous?)
    Add support to parts.contents.

    New elements would be required.  Perhaps::

        <!ELEMENT question_list (question_list_item+)>
        <!ATTLIST question_list
            numbering  (none | local | global)
                                #IMPLIED
            start     NUMBER    #IMPLIED>
        <!ELEMENT question_list_item (question, answer*)>
        <!ELEMENT question %text.model;>
        <!ELEMENT answer (%body.elements;)+>

    Originally I thought of implementing a Q&A list with special
    syntax::

        Q: What am I?

        A: You are a question-and-answer
           list.

        Q: What are you?

        A: I am the omniscient "we".

    Where each "Q" and "A" could also be numbered (e.g., "Q1").
    However, a simple enumerated or bulleted list will do just fine
    for syntax.  A directive could treat the list specially; e.g. the
    first paragraph could be treated as a question, the remainder as
    the answer (multiple answers could be represented by nested
    lists).  Without special syntax, this directive becomes low
    priority.

  - _`body.example`: Examples; suggested by Simon Hefti.  Semantics as
    per Docbook's "example"; admonition-style, numbered, reference,
    with a caption/title.

  - _`body.index`: Index targets.

    See `Index Entries & Indexes
    <./rst/alternatives.html#index-entries-indexes>`__.

  - _`body.literal`: Literal block, possibly "formal" (see `object
    numbering and object references`_ above).  Possible options:

    - "highlight" a range of lines

    - "number" or "line-numbers"

    - "styled" could indicate that the directive should check for
      style comments at the end of lines to indicate styling or
      markup.

      Specific derivatives (i.e., a "python-interactive" directive)
      could interpret style based on cues, like the ">>> " prompt and
      "input()"/"raw_input()" calls.

    See docutils-users 2003-03-03.

  - _`body.sidebar`: Add to the already implemented directive.  Allow
    internal section structure, with adornment styles independent of
    the main document.

  - _`body.list-table`: See `List-Driven Tables
    <rst/alternatives.html#list-driven-tables>`_.

  - _`colorize.python`: Colorize Python code.  Fine for HTML output,
    but what about other formats?  Revert to a literal block?  Do we
    need some kind of "alternate" mechanism?  Perhaps use a "pending"
    transform, which could switch its output based on the "format" in
    use.  Use a factory function "transformFF()" which returns either
    "HTMLTransform()" instance or "GenericTransform" instance?

    If we take a Python-to-HTML pretty-printer and make it output a
    Docutils internal doctree (as per nodes.py) instead of HTML, then
    each output format's stylesheet (or equivalent) mechanism could
    take care of the rest.  The pretty-printer code could turn this
    doctree fragment::

         <literal_block xml:space="preserve">
         print 'This is Python code.'
         for i in range(10):
             print i
         </literal_block>

    into something like this ("</>" is end-tag shorthand)::

         <literal_block xml:space="preserve" class="python">
         <keyword>print</> <string>'This is Python code.'</>
         <keyword>for</> <identifier>i</> <keyword
         >in</> <expression>range(10)</>:
             <keyword>print</> <expression>i</>
         </literal_block>

    But I'm leaning toward adding a single new general-purpose
    element, "phrase", equivalent to HTML's <span>.  Here's the
    example rewritten using the generic "phrase"::

        <literal_block xml:space="preserve" class="python">
        <phrase class="keyword">print</> <phrase
         class="string">'This is Python code.'</>
        <phrase class="keyword">for</> <phrase
         class="identifier">i</> <phrase class="keyword">in</> <phrase
         class="expression">range(10)</>:
            <phrase class="keyword">print</> <phrase
             class="expression">i</>
        </literal_block>

    It's more verbose but more easily extensible and more appropriate
    for the case at hand.  It allows us to edit style sheets to add
    support for new formats, not the Docutils code itself.

    Perhaps a single directive with a format parameter would be
    better::

        .. colorize:: python

           print 'This is Python code.'
           for i in range(10):
               print i

    But directives can have synonyms for convenience.  "format::
    python" was suggested, but "format" seems too generic.

  - _`text.date`: Datestamp.  For substitutions.  The directive could
    be followed by a formatting string, using strftime codes.  Default
    is "%Y-%m-%d" (ISO 8601 date), but time fields can also be used.

    - Combined with the "include" directive, implement canned macros?
      E.g.::

          .. include:: <macros>

          Today's date is |date|.

      Where "macros" contains ``.. |date| date::``, among others.

  - _`text.time`: Timestamp.  For substitutions.  Shortcut for
    ``.. date:: %H:%M``.  Date fields can also be used.

  - _`pysource.usage`: Extract a usage message from the program,
    either by running it at the command line with a ``--help`` option
    or through an exposed API.  [Suggestion for Optik.]


Interpreted Text
----------------

Interpreted text is entirely a reStructuredText markup construct, a
way to get around built-in limitations of the medium.  Some roles are
intended to introduce new doctree elements, such as "title-reference".
Others are merely convenience features, like "RFC".

All supported interpreted text roles must already be known to the
Parser when they are encountered in a document.  Whether pre-defined
in core/client code, or in the document, doesn't matter; the roles
just need to have already been declared.  Adding a new role often
involves adding a new element to the DTD and may require extensive
support, therefore such additions should be well thought-out.  There
should be a limited number of roles.

The only place where no limit is placed on variation is at the start,
at the Reader/Parser interface.  Transforms are inserted by the Reader
into the Transformer's queue, where non-standard elements are
converted.  Once past the Transformer, no variation from the standard
Docutils doctree is possible.

An example is the Python Source Reader, which will use interpreted
text extensively.  The default role will be "Python identifier", which
will be further interpreted by namespace context into <class>,
<method>, <module>, <attribute>, etc. elements (see pysource.dtd),
which will be transformed into standard hyperlink references, which
will be processed by the various Writers.  No Writer will need to have
any knowledge of the Python-Reader origin of these elements.

* Alan Jaffray suggested (and I agree) that it would be sensible to:

  - have a directive and/or command-line option to specify a default
    role for interpreted text
  - allow the reST processor to take an argument for the default role
    (this will be subsumed by the above via the runtime settings
    mechanism)
  - issue a warning when processing documents with no default role
    which contain interpreted text with no explicitly specified role
    (there will always be a default role, so this won't happen)

* Add explicit interpreted text roles for the rest of the implicit
  inline markup constructs: named-reference, anonymous-reference,
  footnote-reference, citation-reference, substitution-reference,
  target, uri-reference (& synonyms).

* Add directives for each role as well?  This would allow indirect
  nested markup::

      This text contains |nested inline markup|.

      .. |nested inline markup| emphasis::

         nested ``inline`` markup

* Implement roles:

  - "acronym" and "abbreviation": Associate the full text with a short
    form.  Jason Diamond's description:

        I want to translate ```reST`:acronym:`` into ``<acronym
        title='reStructuredText'>reST</acronym>``.  The value of the
        title attribute has to be defined out-of-band since you can't
        parameterize interpreted text.  Right now I have them in a
        separate file but I'm experimenting with creating a directive
        that will use some form of reST syntax to let you define them.

    Should Docutils complain about undefined acronyms or
    abbreviations?

    What to do if there are multiple definitions?  How to
    differentiate between CSS (Content Scrambling System) and CSS
    (Cascading Style Sheets) in a single document?  David Priest
    responds,

        The short answer is: you don't.  Anyone who did such a thing
        would be writing very poor documentation indeed.  (Though I
        note that `somewhere else in the docs`__, there's mention of
        allowing replacement text to be associated with the
        abbreviation.  That takes care of the duplicate
        acronyms/abbreviations problem, though a writer would be
        foolish to ever need it.)

        __ `inline parameter syntax`_

    How to define the full text?  Possibilities:

    1. With a directive and a definition list? ::

           .. acronyms::

              reST
                  reStructuredText
              DPS
                  Docstring Processing System

       Would this list remain in the document as a glossary, or would
       it simply build an internal lookup table?  A "glossary"
       directive could be used to make the intention clear.
       Acronyms/abbreviations and glossaries could work together.

       Then again, a glossary could be formed by gathering individual
       definitions from around the document.

    2. Some kind of `inline parameter syntax`_? ::

           `reST <reStructuredText>`:acronym: is `WYSIWYG <what you
           see is what you get>`:acronym: plaintext markup.

       .. _inline parameter syntax:
          rst/alternatives.html#parameterized-interpreted-text

    3. A combination of 1 & 2?

       The multiple definitions issue could be handled by establishing
       rules of priority.  For example, directive-based lookup tables
       have highest priority, followed by the first inline definition.
       Multiple definitions in directive-based lookup tables would
       trigger warnings, similar to the rules of `implicit hyperlink
       targets`__.

       __ ../ref/rst/restructuredtext.html#implicit-hyperlink-targets

  - "annotation": The equivalent of the HTML "title" attribute.  This
    is secondary information that may "pop up" when the pointer hovers
    over the main text.  A corresponding directive would be required
    to associate annotations with the original text (by name, or
    positionally as in anonymous targets?).

  - "figure", "table", "listing", "chapter", "page", etc: See `object
    numbering and object references`_ above.

  - "term"?: Unfamiliar or specialized terminology.

  - "glossary-term": This would establish a link to a glossary.  It
    would require an associated "glossary-entry" directive, whose
    contents could be a definition list::

        .. glossary-entry::

           term1
               definition1
           term2
               definition2

    This would allow entries to be defined anywhere in the document,
    and collected (via a "glossary" directive perhaps) at one point.


Unimplemented Transforms
========================

* _`Footnote & Citation Gathering`

  Collect and move footnotes & citations to the end of a document.
  (Separate transforms.)

* _`Hyperlink Target Gathering`

  It probably comes in two phases, because in a Python context we need
  to *resolve* them on a per-docstring basis [do we? --DG], but if the
  user is trying to do the callout form of presentation, they would
  then want to group them all at the end of the document.

* _`Reference Merging`

  When merging two or more subdocuments (such as docstrings),
  conflicting references may need to be resolved.  There may be:

  * duplicate reference and/or substitution names that need to be made
    unique; and/or
  * duplicate footnote numbers that need to be renumbered.

  Should this be done before or after reference-resolving transforms
  are applied?  What about references from within one subdocument to
  inside another?

* _`Document Splitting`

  If the processed document is written to multiple files (possibly in
  a directory tree), it will need to be split up.  Internal references
  will have to be adjusted.

  (HTML only?  Initially, yes.  Eventually, anything should be
  splittable.)

  Idea: insert a "destination" attribute into the root element of each
  split-out document, containing the path/filename.  The Output object
  or Writer will recognize this attribute and split out the files
  accordingly.  Must allow for common headers & footers, prev/next,
  breadcrumbs, etc.

* _`Navigation`

  If a document is split up, each segment will need navigation links:
  parent, children (small TOC), previous (preorder), next (preorder).
  Part of `Document Splitting`_?

* _`List of System Messages`

  The ``system_message`` elements are inserted into the document tree,
  adjacent to the problems themselves where possible.  Some (those
  generated post-parse) are kept until later, in
  ``document.messages``, and added as a special final section,
  "Docutils System Messages".

  Docutils could be made to generate hyperlinks to all known
  system_messages and add them to the document, perhaps to the end of
  the "Docutils System Messages" section.

  Fred L. Drake, Jr. wrote:

      I'd like to propose that both parse- and transformation-time
      messages are included in the "Docutils System Messages" section.
      If there are no objections, I can make the change.

  The advantage of the current way of doing things is that parse-time
  system messages don't require a transform; they're already in the
  document.  This is valuable for testing (unit tests,
  tools/quicktest.py).  So if we do decide to make a change, I think
  the insertion of parse-time system messages ought to remain as-is
  and the Messages transform ought to move all parse-time system
  messages (remove from their originally inserted positions, insert in
  System Messages section).

* _`Index Generation`


HTML Writer
===========

* Add more support for <link> elements, especially for navigation
  bars.

* Make the admonitions more distinctive and varied.

* Make the "class" attributes optional?  Implies no stylesheet?

* Base list compaction on the spacing of source list?  Would require
  parser support.  (Idea: fantasai, 16 Dec 2002, doc-sig.)

* Add a tool tip ("title" attribute?) to footnote back-links
  identifying them as such.  Text in Docutils language module.

* Add an option to restrict the document title to <head><title> only,
  and not include it in the document body.  Subtitle?

* Insert a comment at the top of HTML files that describes how to deal
  with the broken servers w.r.t. encodings?  Perhaps something like
  this:

      <!--
      If your browser is showing gibberish, the server may be broken.
      Try manually setting the character coding to "UTF-8".  In
      Mozilla/Firefox, do ...  In Internet Explorer, do ...
      For details, see <URL>.
      -->


LaTeX writer
============

* Add an ``--embed-stylesheet`` (and ``--link-stylesheet``) option.


Front-End Tools
===============

* What about if we don't know which Reader and/or Writer we are
  going to use?  If the Reader/Writer is specified on the
  command-line?  (Will this ever happen?)

  Perhaps have different types of front ends:

  a) _`Fully qualified`: Reader and Writer are hard-coded into the
     front end (e.g. ``pep2html [options]``, ``pysource2pdf
     [options]``).

  b) _`Partially qualified`: Reader is hard-coded, and the Writer is
     specified a sub-command (e.g. ``pep2 html [options]``,
     ``pysource2 pdf [options]``).  The Writer is known before option
     processing happens, allowing the OptionParser to be built
     dynamically.  Alternatively, the Writer could be hard-coded and
     the Reader specified as a sub-command (e.g. ``htmlfrom pep
     [options]``).

  c) _`Unqualified`: Reader and Writer are specified as subcommands
     (e.g. ``publish pep html [options]``, ``publish pysource pdf
     [options]``).  A single front end would be sufficient, but
     probably only useful for testing purposes.

  d) _`Dynamic`: Reader and/or Writer are specified by options, with
     defaults if unspecified (e.g. ``publish --writer pdf
     [options]``).  Is this possible?  The option parser would have
     to be told about new options it needs to handle, on the fly.
     Component-specific options would have to be specified *after*
     the component-specifying option.

  Allow common options before subcommands, as in CVS?  Or group all
  options together?  In the case of the `fully qualified`_
  front ends, all the options will have to be grouped together
  anyway, so there's no advantage (we can't use it to avoid
  conflicts) to splitting common and component-specific options
  apart.

* Parameterize help text & defaults somehow?  Perhaps a callback?  Or
  initialize ``settings_spec`` in ``__init__`` or ``init_options``?

* Disable common options that don't apply?

* Implement the "sectnum" directive as a command-line option also?

* @@@ Come up with better names for the most-used tools, and install
  them as scripts.

* Create a single dynamic_ or unqualified_ front end that can be
  installed?


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