[KevinH]

I am not seeing this with iOS iBooks at all. There is no requirement for a toc entry in the nav href to end in a fragment that I see. This is with the iOS books app.

As for splitting, that should be done first. Then do what you want with the body tags. But ids are not needed on body tags for correct links.

Also explore hrefs that end in #top or even with empty fragment # if need be.

Splitting has to change ids on the body tag otherwise duplicate ids are generated.

Please attach a sample epub for iOS Books where links in the nav require fragments to work properly. I have only seen that when the links themselves are incorrect and some ereaders fall back to the unique fragment id. But this is not something to be relied on across Readers.