Hi,
actually we use DocBook V4.2 for the PostgreSQL manuals. I suggest an upgrade to DocBook 5.x. This sounds simple, but it will be a long process with many sub-tasks.

Rationale:

• Sooner or later we MUST migrate as the 4.x series is outdated: V4.2 dates back to 2002. The 4.x series is no longer actively developed since 2006. See: http://www.docbook.org/tdg5/en/html/ch01.html "In October 2006, the DocBook Technical Committee released DocBook V4.5, the last release planned in the 4.x series."
• V5.0 is available since 2009. See: http://www.docbook.org/tdg5/en/html/ch01.html: "DocBook V5.0 became an official Committee Specification in June 2009 and became an official OASIS Standard in October 2009."
• Actually the technical committee has the third Candidate Release for V5.1.

PROs:

• The formal part of the migration is supported by existing tools: http://docbook.org/docs/howto/#convert4to5 (nevertheless some scripts written by ourself will be necessary).
• The normative schema for Docbook 5.x is written in RELAX NG. Additionally the technical committee converts this normative schema to a XSD schema and to DTD, which are not normative but very near to RELAX NG and will fit for most applications. Hence, we have the choice between three schema syntaxes and everybody can use his favourite one.
• Our source file format will switch from SGML to XML. This implies that we have access to all XML features like XLink, XPath, XSLT, XSL-FO, SVG, MathML, namespaces, ... .

CONs:

• The migration from 4.x to 5.x implies major changes at 3 different levels.
• DocBook structure: Previously it was defined in SGML syntax (DTD). Now it is defined in RELAX NG schema language plus Schematron rules.
• DocBook files: Previously we used SGML syntax for our files. We must convert them to a valid XML syntax, eg: tag omission.
• Tools and style sheets: All tools which operate at the native SGML-level (editors, conversions, ...) must be replaced by XML conforming tools. As valid XML implicitly conforms to a valid SGML syntax this step may be accomplished by reconfiguring some of the tools, eg.: .emacs.

What I have done so far is:

• Conversion of sgml files to valid xml syntax with a perl skript. I failed to use 'osx' or 'spam'.
• Conversion of these xml files to Docbook5.x format using xsltproc and Docbooks xslt-migration skripts.
• Creation of html files using xsltproc and Docbooks xslt skripts.
• Creation of fo files using xsltproc and Docbooks xslt skripts.
• Creation of pdf files using fop.
• The conversions needs less than 10 minutes on a Intel i5 processor.
  

This is a very first raw round-trip with one output file per sgml file and output type. Not supported: entities (__gt__ as a surrogate), <[CDATA and similar SGML constructs, PostgreSQL specific style sheets, Makefile, additional errors occur, .... .  I append one file of every new format for the chapter "Advanced Features": xml (the new source), html, fo, pdf.

Any ideas or suggestions? Shall we go further on this way? Has anybody more experiences in SGML-->XML conversions or Docbook 4.x --> 5.x conversions?

Kind regards
Jürgen Purtz