Originally Posted by kovidgoyal
Finally, the extra markup in kepubs is almost certainly there to allow for annotations and bookmarking and likely serves no other purpose. Apparently the developers at Kobo, like the developers at Amazon with KF8 (which uses a very similar scheme) chose not to implement the EPUB 3 CFI spec.
That is correct. I have looked at the stored bookmarks on the device for kepubs to check this. And to compare with what they are doing for epubs and other formats.
I just had a quick look at the EPUB 3 CFI spec. Is the bookmark in the calibre viewer based on this? From the examples, it looks similar, but that might be a coincidence. The reason for the interest is that I have been meaning to look see if I could translate bookmarks between the Kobo to the viewer.