"David Sklar writes about writing his book "Learning PHP 5" and how he used DocBook. I used DocBook for my book ("Professionelle Softwareentwicklung mit PHP 5"), too, and documented the writing process in a separate weblog."
Vex hides the raw XML tags from the user, providing instead a wordprocessor-like interface. Because of this, Vex is best suited for "document-style" XML documents such as XHTML and DocBook rather than "data-style" XML documents.
LyX is a document processor that encourages an approach to writing based on the structure of your documents (WYSIWYM), and not simply their appearance (WYSIWYG).
"What are the tools and processes that I used to write Learning PHP 5? Each chapter (and appendix) is its own file, formatted with the Docbook Lite XML dialect."
"David Sklar writes about writing his book "Learning PHP 5" and how he used DocBook. I used DocBook for my book ("Professionelle Softwareentwicklung mit PHP 5"), too, and documented the writing process in a separate weblog."