Hello and welcome!This is the official home page for DocBook 5: The Definitive Guide. The definitive guide is the official documentation for DocBook. The latest edition covers DocBook V5.0. It was published by O'Reilly Media and XML Press. In support of DocBook users everywhere, this book and its source XML are available online. Of course, you're always free to buy a copy, too, if you'd like :-).
