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# docidx_lang_syntax(n) 1.0 tcllib "Documentation tools"

## Name

docidx_lang_syntax - docidx language syntax

## Description

This document contains the formal specification of the syntax of the docidx markup language, version 1 in Backus-Naur-Form. This document is intended to be a reference, complementing the docidx language command reference. A beginner should read the much more informally written docidx language introduction first before trying to understand either this document or the command reference.

## Fundamentals

In the broadest terms possible the docidx markup language is like SGML and similar languages. A document written in this language consists primarily of markup commands, with text embedded into it at some places.

Each markup command is a just Tcl command surrounded by a matching pair of [ and ]. Which commands are available, and their arguments, i.e. syntax is specified in the docidx language command reference.

In this document we specify first the lexeme, and then the syntax, i.e. how we can mix text and markup commands with each other.

## Lexical definitions

In the syntax rules listed in the next section

1. <TEXT> stands for all text except markup commands.

2. Any XXX stands for the markup command [xxx] including its arguments. 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.

3. <WHITE> stands for all text consisting only of spaces, newlines, tabulators and the comment markup command.

## Syntax

The rules listed here specify only the syntax of docidx documents. The lexical level of the language was covered in the previous section.

Regarding the syntax of the (E)BNF itself

1. The construct { X } stands for zero or more occurrences of X.

2. The construct [ X ] stands for zero or one occurrence of X.

The syntax:

    index     = defs
                INDEX_BEGIN
                [ contents ]
                INDEX_END
                { <WHITE> }
    defs      = { INCLUDE | VSET | <WHITE> }
    contents  = keyword { keyword }
    keyword   = defs KEY ref { ref }
    ref       = MANPAGE | URL | defs

At last a rule we were unable to capture in the EBNF syntax, as it is about the arguments of the markup commands, something which is not modeled here.

1. The arguments of all markup commands have to be plain text, and/or text markup commands, i.e. one of

   1. lb,

   2. rb, or

   3. vset (1-argument form).

## 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.

## See Also

docidx_intro, docidx_lang_cmdref, docidx_lang_faq, docidx_lang_intro

## Keywords

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

## Category

Documentation tools

## Copyright

Copyright © 2007-2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>