[JimmXinu]

I've been revisiting the idea of including epub version 3 support natively in EpubMerge.

Currently, EM uses Calibre's Convert to downgrade epub3 to epub2. This works, but Convert is rather intensive with what it changes.

I think I have a handle on how I'd implement epub3 natively in EM. The problem is that I don't really want to deal with epub3 AND epub2 input at the same time, or with epub3 AND epub2 output.

Calibre's Polish Upgrade book internals appears to be much less heavy handed about what it changes when going from epub2 to epub3. The epubs it produces are NOT epub2 back compatible, however. EM output would NOT be epub2 compliant (no NCX TOC). But Convert is still there.

Any opinions on whether reversing EM from epub2 only (albeit with auto-convert) to epub3 only (with auto-polish) is worthwhile?

I will also be looking at epub3 in EpubSplit and FanFicFare (anthology feature, at least).