Just some thoughts regarding using multiple references from the "Things to note" section of your blog entry:
http://sigildev.blogspot.com/2010/04...tics-menu.html
I recently converted an older print edition to epub and used 2 titles, 2 introductions + 2 prefaces.
The 2 titles were for the title page & the bastard title. And this was a 2nd edition with introductions & prefaces from each.
I wasn't sure exactly what the standard is for handling these since, as you mentioned, it's not really covered in the standard -- although I do recognize that they could have been combined into one file & one reference each.
The available types in the standard also don't give an option for a frontispiece and I toyed with the idea of tagging/including it as "title" too.
Similarly, many textbooks have 2 tables of contents - one short and one detailed. Before reading your post I would have tagged them individually.
I guess this may just boil down to how individual reading systems end up using these tags.
Thanks for a fantastic program!
Troy