This framework has been written for the Velocity documentation and we also tried to do a reasonably good job in documentating it.

In any case, the last and final word is in the Subversion repository for the DocBook Framework at http://svn.apache.org/repos/asf/velocity/docbook/trunk/

The reference on how to setup and build documentation is the Velocity documentation at http://svn.apache.org/repos/asf/velocity/docs/ and also the DocBook Framework documentation itself which is located in the docs/ subfolder of the distribution. If in doubt, please check there on how the framework is used.