Provided by: tcllib_1.21+dfsg-1_all 
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.
... [key {markup language}] ...
... [manpage thefile \
{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, and the package it describes, will undoubtedly contain bugs and other problems. Please
report such in the category doctools of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist].
Please also report any ideas for enhancements you may have for either package and/or documentation.
When proposing code changes, please provide unified diffs, i.e the output of diff -u.
Note further that attachments are strongly preferred over inlined patches. Attachments can be made by
going to the Edit form of the ticket immediately after its creation, and then using the left-most button
in the secondary navigation bar.
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>
tcllib 1.0 docidx_lang_intro(3tcl)