EPUB
There are many digital book formats. The most widely supported format is EPUB, and that is the format created by Gedcom Publisher. EPUB is supported by a large number of devices and software programs, including Amazon Kindle Fire, but not the standard Kindle.
MOBI
The standard Kindle and some other devices support the MOBI format. Amazon provides a program named KindleGen for converting an EPUB book to the MOBI format, however, not all EPUB features are compatible with the conversion process. Gedcom Publisher creates two versions of the EPUB file to adjust for the limitations of the MOBI format.
Two Output Files
After you use the Make Book command in Gedcom Publisher, you will have two new files in the same folder as the Gedcom Publisher file (".gpfile"). The first file is an EPUB file you can use with any e-book reader. The second is an EPUB file you should use if you want to convert your EPUB book to a MOBI file.
Both new files use the same name as your Gedcom Publisher file. If your file is "MyBook.gpfile", Gedcom Publisher will make:
MyBook.epub– This is your book in EPUB3 format. You can use it with any modern e-book reader. It uses some EPUB3 features that are not compatible with conversion to the MOBI format.MyBook-mobi.epub– This is your book in EPUB3 format, but this version avoids using features that are not compatible with conversion to the MOBI format.
If you submit your book to Amazon or any other publisher that converts to the MOBI format, submit the -mobi.epub version of your book. Also, if you use Kindle Viewer or the KindleGen tool from Amazon, use the -mobi.epub version. For most other purposes, use the other version without the -mobi suffix.
AZK
When you use KindleGen, the program creates two versions of your book and stores them both in the ".mobi" file. One of the versions is designed for older Kindle devices, and one is for newer. The AZK format is for newer devices. When you submit the ".mobi" file to Amazon, they keep both versions, but they download only the appropriate version when a user requests a download to a specific device.
If you are using a Kindle Fire, or a Kindle app running on a PC, tablet, or smartphone, you may want to sideload the book to that device for testing. The Kindle (iOS) help page describes how to create an AZK file and how to sideload it to an iOS device. For other devices, the process of creating the AZK format is the same, but the steps to transfer to the device will be different.