IBooks Author analysis by the co-chairman of the CSS Working Group
glazman.org
glazman.org
But if I were a publisher and I wanted to make a nice book, I would either do the following: if I already had a good authoring tool I would use it for any of the distributed platforms and if I didn't have any authoring tool and the one proposed by Apple was appealing to me but I wanted to remain portable accross platforms I would keep the form and content completely separated (as css is meant to html) and use the Apple tools to create a good format for the Apple platform and use something else for others platforms.
I think the problem is not about standards or anything else, I think the problem is that we can't accept that a company creating so many appealing tools always put so much burden and restrictions in their use. Especially in this case where the tool is 'free' but has a very restrictive license. But as everything else, anyone is free to make a better product or an equivalent product with a better license, this is competition, this is good.
Quotes from the linked post like this: "The ability to control the size of each column and column gap was recently discussed in the CSS WG. The Group decided that allowing setting of individual column width and column gap width is not a feature considered for the first REC of this document.", suggest, to me at least, that Apple created their proprietary format because standards didn't and still don't cover the fictionality they have in mind for these interactive books. I'd rather Apple do that than hastily muscle their implementation into the standards.
The settings for column width and column gap width, in particular, sound like they'd be critical for making a really attractive ebook. If the epub 3 standard doesn't support such basic functionality, there's a problem.
This isn't quite the same as the stuff Microsoft pulled -- MS created tools that claimed to generate "HTML" (but which in reality only worked in Internet Explorer) and encouraged their use on the public web. Apple isn't claiming these things are ePub 3 (or any other standard format), and in fact they're explicitly forbidding their use in a generic context. I'm not a fan of their licensing restrictions, but at least they're not claiming (or even implying) in any way that these ebooks are standards-based.
And this greatly clarifies whether the format is ePub or not.