[Notjohn]

Just for fun, I used Kindleunpack to deconstruct a book of mine, converted on the KDP platform for sale on Amazon. I upload an epub to the KDP, since I need the epub for the other retailers, and since it happens to be the easiest way to upload an entire book in a single package, rather than as a zip file.

Kindleunpack produced two files, one in a folder called Mobi7, the other in a folder called Mobi8 which I take to be the equivalent of KF8 format (for the Fire and other newer devices and apps). To my astonishment, the file in the Mobi8 folder had the extension *.epub.

Is Amazon actually delivering an epub to customers who are reading on the Fire and related devices/apps?

(The Mobi7 folder contained a much smaller file with the extension *.htm, plus an OPF and an NCX file.)