This paragraph presents a global picture about what functionality xpt delivers and how and where to use it. Some use cases.
DocBook is a XML vocabulary (http://en.wikipedia.org/wiki/DocBook) for writing books and articles. Often a make tool-chain is used, where a DocBook XML source is transformed into a certain format, e.g. HTML or PDF. A place where, with every version of a document, manual action is required: releaseinfo and pubdate.