NAME

       docidx_lang_intro - docidx language introduction

DESCRIPTION

       This document is an informal introduction to version 1 of the docidx markup language based
       on a multitude of examples. After reading this a writer should be ready to understand  the
       two  parts  of the formal specification, i.e. the docidx language syntax specification and
       the docidx language command reference.

   FUNDAMENTALS
       While the docidx markup language is quite similar to the doctools markup language, in  the
       broadest  terms  possible, there is one key difference. An index consists essentially only
       of markup commands, with no plain text interspersed between them, except for whitespace.

       Each markup command is a Tcl command surrounded by a matching pair of [ and ].  Inside  of
       these  delimiters  the  usual rules for a Tcl command apply with regard to word quotation,
       nested commands, continuation lines, etc. I.e.

              {file description}] ...

   BASIC STRUCTURE
       The most simple document which can be written in docidx is
              [index_begin GROUPTITLE TITLE]
              [index_end]

       Not very useful, but valid. This also shows us that all docidx documents consist  of  only
       one part where we will list all keys and their references.

       A  more  useful  index  will  contain at least keywords, or short 'keys', i.e. the phrases
       which were indexed. So:
              [index_begin GROUPTITLE TITLE]
              [key markup]
              [key {semantic markup}]]
              [key {docidx markup}]
              [key {docidx language}]
              [key {docidx commands}]
              [index_end]

       In the above example the command key is used to declare the keyword phrases we wish to  be
       part of the index.

       However a truly useful index does not only list the keyword phrases, but will also contain
       references to documents associated with the keywords. Here is a made-up index for all  the
       manpages in the module base64:
              [index_begin tcllib/base64 {De- & Encoding}]
              [key base64]
              [manpage base64]
              [key encoding]
              [manpage base64]
              [manpage uuencode]
              [manpage yencode]
              [key uuencode]
              [manpage uuencode]
              [key yEnc]
              [manpage yencode]
              [key ydecode]
              [manpage yencode]
              [key yencode]
              [manpage yencode]
              [index_end]

       In  the above example the command manpage is used to insert references to documents, using
       symbolic file names, with each command belonging to the last key command coming before it.

       The other command to insert references is url. In contrast to  manpage  it  uses  explicit
       (possibly  format-specific)  urls  to describe the location of the referenced document. As
       such this command is intended for the creation of references to external  documents  which
       could not be handled in any other way.

   ADVANCED STRUCTURE
       In  all previous examples we fudged a bit regarding the markup actually allowed to be used
       before the index_begin command opening the document.

       Instead of only whitespace the two templating commands include and vset are also  allowed,
       to  enable  the  writer to either set and/or import configuration settings relevant to the
       table of contents. I.e. it is possible to write
              [include FILE]
              [vset VAR VALUE]
              [index_begin GROUPTITLE TITLE]
              [index_end]
       Even more important, these two commands are allowed anywhere where  a  markup  command  is
       allowed, without regard for any other structure.
              [index_begin GROUPTITLE TITLE]
              [include FILE]
              [vset VAR VALUE]
              [index_end]
       The only restriction include has to obey is that the contents of the included file must be
       valid at the place of the inclusion. I.e. a file included before index_begin  may  contain
       only  the  templating  commands  vset and include, a file included after a key may contain
       only manape or url references, and other keys, etc.

   ESCAPES
       Beyond the 6 commands shown so far we have two more available.  However their function  is
       not  the  marking  up of index structure, but the insertion of characters, namely [ and ].
       These commands, lb and rb respectively, are required because our use of [ and ] to bracket
       markup commands makes it impossible to directly use [ and ] within the text.

       Our  example  of their use are the sources of the last sentence in the previous paragraph,
       with some highlighting added.
              These commands, [cmd lb] and [cmd lb] respectively, are required
              because our use of [lb] and [rb] to bracket markup commands makes it
              impossible to directly use [lb] and [rb] within the text.

FURTHER READING

       Now that this  document  has  been  digested  the  reader,  assumed  to  be  a  writer  of
       documentation  should  be  fortified  enough  to  be  able to understand the formal docidx
       language syntax specification as well. From  here  on  out  the  docidx  language  command
       reference  will also serve as the detailed specification and cheat sheet for all available
       commands and their syntax.

       To be able to validate a document while writing it, it is also recommended to  familiarize
       oneself with Tclapps' ultra-configurable dtp.

       On  the  other hand, docidx is perfectly suited for the automatic generation from doctools
       documents, and this is the route Tcllib's easy and simple dtplite goes, creating an  index
       for a set of documents behind the scenes, without the writer having to do so on their own.

BUGS, IDEAS, FEEDBACK

       This  document,  will  undoubtedly contain bugs and other problems.  Please report such in
       the       category       doctools       of       the       Tcllib       SF        Trackers
       [http://sourceforge.net/tracker/?group_id=12883].    Please  also  report  any  ideas  for
       enhancements you may have.

SEE ALSO

       docidx_intro, docidx_lang_cmdref, docidx_lang_syntax

KEYWORDS

       docidx commands, docidx language, docidx markup, docidx syntax, markup, semantic markup

CATEGORY

       Documentation tools

COPYRIGHT

       Copyright (c) 2007-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>