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DocBook.orgDocBook 5: The Definitive Guide is Copyright © 2010 Norman Walsh.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, as spelled out in the book's legal notice.
Versions available:
Version 1.0 is DocBook 5: The Definitive Guide from O'Reilly Media and XML Press. You can get it in electronic or dead-tree form.
Version 1.1 is a “work in progress” that purports to document DocBook V5.0+. That is, it documents DocBook V5.0 with some additional material that will eventually appear in DocBook V5.1.
Version 1.3 is a “work in progress” that purports to document DocBook V5.1b2. That is, it documents the schema that will eventually become the official DocBook V5.1 schema. (Eventually the 1.1 link above will be replaced by a link to this version, but since the early betas of V5.1 are likely to be a bit unstable, I'm leaving both online for the time being.)