# doctoc_lang_intro(3tcl) 1.0 doctools "Documentation tools"

## Name

doctoc_lang_intro - doctoc language introduction

## Description

This document is an informal introduction to version 1.1 of the doctoc 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 doctoc language syntax specification and the doctoc language command reference.

### Fundamentals

While the doctoc markup language is quite similar to the doctools markup language, in the broadest terms possible, there is one key difference. A table of contents 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.

        ... [division_start {Appendix 1}] ...

      ... [item thefile \
              label {file description}] ...

### Basic structure

The most simple document which can be written in doctoc is

        [toc_begin GROUPTITLE TITLE]
        [toc_end]

This also shows us that all doctoc documents consist of only one part where we will list items and divisions.

The user is free to mix these as she sees fit. This is a change from version 1 of the language, which did not allow this mixing, but only the use of either a series of items or a series of divisions.

We will discuss the commands for each of these two possibilities in the next sections.

### Items

Use the command item to put an item into a table of contents. This is essentially a reference to a section, subsection, etc. in the document, or set of documents, the table of contents is for. The command takes three arguments, a symbolic name for the file the item is for and two text to label the item and describe the referenced section.

Symbolic names are used to preserve the convertibility of this format to any output format. The actual name of any file will be inserted by the chosen formatting engine when converting the input, based on a mapping from symbolic to actual names given to the engine.

Here a made up example for a table of contents of this document:

    [toc_begin Doctoc {Language Introduction}]
    [item 1 DESCRIPTION]
    [item 1.1 {Basic structure}]
    [item 1.2 Items]
    [item 1.3 Divisions]
    [item 2 {FURTHER READING}]
    [toc_end]

### Divisions

One thing of notice in the last example in the previous section is that the referenced sections actually had a nested structure, something which was expressed in the item labels, by using a common prefix for all the sections nested under section 1.

This kind of structure can be made more explicit in the doctoc language by using divisions. Instead of using a series of plain items we use a series of divisions for the major references, and then place the nested items inside of these.

Of course, instead of the nested items we can again use divisions and thus nest arbitrarily deep.

A division is marked by two commands instead of one, one to start it, the other to close the last opened division. They are:

division_start

  This command opens a new division. It takes one or two arguments, the title of the division, and the symbolic name of the file it refers to. The latter is optional. If the symbolic filename is present then the section title should link to the referenced document, if links are supported by the output format.

division_end

  This command closes the last opened and not yet closed division.

Using this we can recast the last example like this

    [toc_begin Doctoc {Language Introduction}]
    [division_start DESCRIPTION]
    [item 1 {Basic structure}]
    [item 2 Items]
    [item 3 Divisions]
    [division_end]
    [division_start {FURTHER READING}]
    [division_end]
    [toc_end]

Or, to demonstrate deeper nesting

    [toc_begin Doctoc {Language Introduction}]
    [division_start DESCRIPTION]
    [division_start {Basic structure}]
    [item 1 Do]
    [item 2 Re]
    [division_end]
    [division_start Items]
    [item a Fi]
    [item b Fo]
    [item c Fa]
    [division_end]
    [division_start Divisions]
    [item 1 Sub]
    [item 1 Zero]
    [division_end]
    [division_end]
    [division_start {FURTHER READING}]
    [division_end]
    [toc_end]

And do not forget, it is possible to freely mix items and divisions, and to have empty divisions.

    [toc_begin Doctoc {Language Introduction}]
    [item 1 Do]
    [division_start DESCRIPTION]
    [division_start {Basic structure}]
    [item 2 Re]
    [division_end]
    [item a Fi]
    [division_start Items]
    [item b Fo]
    [item c Fa]
    [division_end]
    [division_start Divisions]
    [division_end]
    [division_end]
    [division_start {FURTHER READING}]
    [division_end]
    [toc_end]

### Advanced structure

In all previous examples we fudged a bit regarding the markup actually allowed to be used before the toc_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]
    [toc_begin GROUPTITLE TITLE]
    ...
    [toc_end]

Even more important, these two commands are allowed anywhere where a markup command is allowed, without regard for any other structure.

    [toc_begin GROUPTITLE TITLE]
    [include FILE]
    [vset VAR VALUE]
    ...
    [toc_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 toc_begin may contain only the templating commands vset and include, a file included in a division may contain only items or divisions commands, etc.

### Escapes

Beyond the 6 commands shown so far we have two more available. However their function is not the marking up of toc 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 doctoc language syntax specification as well. From here on out the doctoc 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, doctoc is perfectly suited for the automatic generation from doctools documents, and this is the route Tcllib's easy and simple dtplite goes, creating a table of contents 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. 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

doctoc_intro, doctoc_lang_cmdref, doctoc_lang_syntax

## Keywords

doctoc commands, doctoc language, doctoc markup, doctoc syntax, markup, semantic markup

## Category

Documentation tools

## Copyright

Copyright © 2007 Andreas Kupries <andreas_kupries@users.sourceforge.net>