docbook changelog

Hi all!

This is my first email here.
I am looking for a DocBook changelog.
Especially I'd like to know what changed form v4.1.2 to 4.4.

Besides, is there a simple way, to convert v4.1.2 documents to v4.4?

My original problem:
I have to transform DOC/DOCX documents to DocBook v4.4.
DocBook roundtripping ended up in error.
LibreOffice resulted DocBook v4.1.2.
Now I am planning to compare XSD files and write a custom XSLT to do the job.

Thanx for help in advance!

Jazoja