DocBook.orgThe version 5.0 release is a complete rewrite of DocBook in RELAX NG. The intent of this rewrite is to produce a schema that is true to the spirit of DocBook while simultaneously removing inconsistencies that have arisen as a natural consequence of DocBook's long, slow evolution. The Technical Committee has taken this opportunity to simplify a number of content models and tighten constraints where RELAX NG makes that possible.
The Technical Committee provides the DocBook 5.0 schema in other schema languages, including W3C XML Schema and an XML DTD, but the RELAX NG Schema is the normative schema.
There are no current candidate releases of DocBook V5.x.