I've spent a few hours today looking at The Daisy Pipeline Project:
http://daisymfc.sourceforge.net/
There are numerous transformers used within the Pipeline tool that you might find of note. One thing mentioned in the reference material for the ePUB Creator script (
http://daisymfc.sourceforge.net/doc/...PSCreator.html) that caught my eye:
The OPS Specification is quite picky about what kind of text documents can be used within an EPUB. You can only use XHTML 1.1 (not 1.0) documents, or DTBook 2005-2 (not 2005-1 or 2005-3) documents.
I thought you might find this of note if you're not already aware.
---------------------------------------------------------jp english