DocBook XML is a XML application, and is derived from SGML DocBook. It can be used to generate HTML, plain text, PDF and even more formats of output from a single source.

We use DocBook XML to write the complete documentation for moregroupware, so if you want to help, you should just go ahead and have a look at the XML files in the docs/docbook/ directory of the moregroupware distribution. The central place for more information is http://www.docbook.org/ .