In retrospect, I think that first question didn't quite come out the way I meant it. My apologies.
Your comments to the second question answered my poorly worded request though. Since I'm looking to future-proof my library now (before it gets any larger or harder to manage), I'm trying to find good tools and practices to implement now. Having pretty much decided on EPUB, I was confused by the sudden appearance of a new contender.
Do you have a "smallish" ebook that uses this TEI-MEK structure? (Not sure of this format's name.) I'm only looking for a couple of sample pages tied together into a book with various example implementations of the XML scheme. I don't read Hungarian and the DTDs were pretty much over my head. But I might be able to figure things out with an example file. I probably should be learning XML - but I would rather wait for improved tools that can provide assistance and automation of tasks.
Edit: Or I could just re-read your original post and download the sample book!