Originally Posted by pdurrant
You might think of KF8 as a kind of compiled ePub, just as the original Mobi was a kind of compiled OEB.
Exactly. In OEB all the end users formats were compiled versions of OEB. There were three, IMP, LIT, and MOBI. All were based on OEB and if you had the source it was fairly easy to make any of them although all three formats had extensions to the format specification.
Amazon's KF8 is actually targeted toward ePub3 rather than ePub version 2 but, except for the Fixed layout version it is a proper subset of ePub3 although they succumbed to including some extensions to make some old mobi kludges continue to work.