hxa7241 you are a gem, this is just the type of examples I need to get up to speed. And in making comparisons it is invaluable - many thanks.
I must have read about alternative stylesheets somewhere on the IDPF site, but later when I wanted to make sure, I could find no reference. Your confirmation is as good as gold as far as I am concerned.
Your advice on using XHTML+CSS will be adhered to as well, at least to begin with, in the end hopefully all the readers will improve in this regard.
By the way your practical guide has been the best resource for clarifying the standard that I have come across, I am in your debt.
I hope, as things unfold, the standard embraces a number of “standard” DTDs along with arbitrary XML — DTbooks has virtues, TEI is essential for serious academic work (it really needs a collection of stylesheets to be anywhere near functional), DocBook etc.,.
The foreign matter I was thinking to include, is part of long term project, that is providing typographical stylesheets that produce PDF for readers to display (I don't expect the readers to do this transformation, rather to have the capacity inbuilt into the epub and produced on demand via a local computer).
Early in 2008 I hope to put in the public domain, with the help of Sydney based company, an easy and reliable system for creating world-wide unique identifiers. That is a hole that needs fixing sooner rather than later, along with a register of works, authors, editions and publishers based on unique identifiers.
Exciting times for e–books ahead, epub need not do everything, but as a standard it is sorely needed.
Many thanks for your answers and most of all your examples.