[KevinH]

As a professor, I was quite interested and downloaded the new iBooks Authoring tool hoping to be able to see how it compares with Sigil and possibly use it to produce valid epub3.

Instead, what I found was a blatant attempt to embrace and destroy the epub3 spec

* iBooks Author will not even load an epub (or any version)
* iBooks author will not let you publish to anywhere but the IBook Store
* if you export to "iBooks" you will get a completely bastardized epub with its own mimetype file "application/x-ibooks+xip" that has the same basic layout as an epub but that seems to use its own fixed format layout and has lots of Apple extensions.

To see all of this, Go to the Mac App Store and download iBook Author.app for free and then open one of its templates and export it to iBooks format.

The results .iBooks file can be unzipped to see how badly they have bastardized the epub format.

A real shame.

Oh well.