slackbuilds_ponce/system/docbook-xml

DocBook is a schema (available in several languages including RELAX NG,
SGML and XML DTDs, and W3C XML Schema) maintained by the DocBook
Technical Committee of OASIS. It is particularly well suited to books
and papers about computer hardware and software (though it is by no
means limited to these applications).

This package includes: 4.1.2, 4.2, 4.3 and 4.4.

4.5 isn't included because it is already provided by the linuxdoc-tools
package that comes with Slackware.