docidx_lang_syntax - docidx language syntax

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

tcllib                                                 1.0                              docidx_lang_syntax(3tcl)

       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 docidxlanguagecommandreference.  A beginner should read the much more informally written docidxlanguageintroduction  first
       before trying to understand either this document or the command reference.

       In  the broadest terms possible the docidxmarkuplanguage 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 docidxlanguagecommandreference.

       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.

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

       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.

       docidx_lang_syntax - docidx language syntax

       docidx_intro, docidx_lang_cmdref, docidx_lang_faq, docidx_lang_intro

       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).