Tools required for building the documentation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* GNU make 3.80 or later
* DocBook 4.1.2 or later
* The DocBook XML DTD (also known as DocBk XML)
* DocBook XSL stylesheets -- version 1.50.0 or later is recommended.

I am not quite sure which tools work, but I used the following
ones successfully, so they are required:

* xmllint (part of libxml2) is used for validation.
* xsltproc (part of libxslt1) is used for transforming XML files into HTML
  files. Version 1.0.18 or later is recommended.

On Red Hat systems you need the following packages:
libxml2, libxslt, docbook-dtds, docbook-style-xsl

On Debian you will need these packages:
docbook-xml, docbook-xsl, xsltproc, libxml2-utils


Building the documentation
~~~~~~~~~~~~~~~~~~~~~~~~~~

The documentation and its translations reside in subdirectories.
When building the documentation, the generated HTML files are
placed in subdirectories of the 'HTML' directory.

IMPORTANT: Do NOT place sensitive files under 'HTML'!
           It is for generated documentation only.
           The whole directory tree is wiped out by the Makefile
           when running 'make distclean' or 'make clean'.


A few words about SGML catalog files
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

As far as I know, the document type declaration in XML files requires
both a public and a system identifier. For example:

<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
  "/usr/share/sgml/docbook/dtd/xml/4.1.2/docbookx.dtd">

where

  "-//OASIS//DTD DocBook XML V4.1.2//EN"

is the public, and

  "/usr/share/sgml/docbook/dtd/xml/4.1.2/docbookx.dtd"

is the system identifier.

The problem is that the system identifier is most probably system-dependent.
To avoid the need to manually fix the system identifiers before building the
documentation, I've decided to use SGML catalogs. If you have your catalogs
set up correctly, xmllint and xsltproc will use them to find the DTDs
based on the public identifiers.

Note that this works only if public identifiers override system identifiers
(i.e. the catalog file must contain 'OVERRIDE YES'). (I had no problem with
these on my system, since the Debian people took care of everything. ;-))
