The information found in these stylesheets is designed to follow
http://docs.oasis-open.org/templates/OASISSpecificationTemplateV4.1.html

The oasis-specification-*.xsl files layer on top of the DocBook stylesheets
the differences in appearances of the OASIS constructs.  While based on
the oasis-docbook-*.xsl stylesheets, a number of changes were necessary to
accommodate new OASIS layouts.

The titlepage.templates-*.xml files are input to the DocBook stylesheet library
template/titlepage.xsl stylesheet to synthesize the corresponding
titlepage-*.xsl stylesheet fragments used by the OASIS stylesheets.

Please see the documentation for the use of the other files.