The DocBook Project
The DocBook Project supports the open-source development of a variety of DocBook resources; in particular, the DocBook XSL stylesheets.
DocBook provides a system for writing structured documents using SGML or XML. It is particularly well-suited to books and papers about computer hardware and software, though it is by no means limited to them.
In short, DocBook is an easy-to-understand and widely used DTD. Dozens of organizations use DocBook for millions of pages of documentation, in various print and online formats, worldwide.
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