I've been looking at a few different ePub3s (programatically, not through ePub-specific software), and notive that the navigation document containing the TOC doesn't seem to be constantly named.
Is there a way of finding it, other than through reading each file for the relevant HTML?
Thanks
Edit: Digging around further, perhaps the package.opf is the answer: <item id="nav_1" href="nav.xhtml" media-type="application/xhtml+xml" properties="nav"></item>
?