Like devices, epublication formats are numerous and varied, with subtle differences between them, but large divergences in purpose, capability, and device support. (iampariah.com)
Consequently, it's most logical and productive to think of epublications in terms of format classes, with each class offering a particular combination of purpose, capability, and device support. (iampariah.com)
Even if you don't decide to roll your own epublication, you'll know what is involved and won't pay someone a ginourmous fee to do something you might be able to do in an hour or two. (storyfix.com)