The docbook project supports the open-source development of a variety of DocBook resources; in particular, the DocBook XSL stylesheets. In 2009 the epub Docbook XSL stylesheet was added for output docbook xml files to ePub files.
 About DocBook
DocBook is an XML vocabulary that lets you create documents in a presentation-neutral form that captures the logical structure of your content. Using free tools along with the DocBook XSL stylesheets, you can publish your content as HTML pages and PDF files, and in many other formats.
- Docbook reference book
- Docbook XSL book It's the bible in Docbook, but it's way out of date. It doesn't even mention the epub XSL.
- DocBook + Epub Brain Dump Page is a list of hacks/tips/pointers maintained by Robert Nagle
- DocBook XSL Mailing List is the place to find help for XSL questions.
- The HTML parameter page lists all the easy shortcuts for customizing your docbook output. Most of it applies to docbook to epub. See also: the general technical reference guide to templates, xsl-fo, etc.
The core DocBook standard is the DocBook Document Type Definition (DTD) maintained by the DocBook Technical Committee in OASIS. The DTD defines the vocabulary of content elements that an author can use and how they relate to each other. For example, a book element can contain a title element, any number of para elements for paragraphs, and any number of chapter elements. Using the DTD and XML syntax, authors mark up their text content with tag names enclosed in angle brackets like <chapter>. The markup is similar to HTML, but with more tags and tighter rules.
The schema for DocBook is called colophon. An example is:
<book xmlns='http://docbook.org/ns/docbook'> <title>Example colophon</title> <colophon> <para>Draft versions of the first edition of this book were produced with the DocBook DSSSL Stylesheets. Final production was performed with Troff.</para> <para>XSLT and XSL were used to produce the second edition.</para> </colophon> </book>
- Pandoc can work with files in this format.