The ITMSP - iTunes Store Package may be used to store all kinds of content sold iTunes, from videos, to music, to digital books. These files are then submitted for review by the iTunes store. using the iTunes Producer for multimedia and book content or Application Loader for applications.This file is essential for any publishing company or freelancer who is looking to sell their products on the iTunes Store. This file is a one-catch-all format that makes it easy to submit your books and multimedia to the iTunes Store.
I use iBooks Author to create ITMSP files that are then published on the Apple iBookstore. ITMSP are great if you want to submit media that you want to be sold on the iTunes store.