[rashkae]

It was an interesting sample to look at thank you. One thing to note about this file is that it is a pure epub3 file that only has nav.xhtml and no backwards compatible toc.ncx file. This is probably very rare, as most commercially available books will have the toc.ncx. Converting to epub3 in calibre is the only time I've seen a book without.

When sending the books to Kobo with KTE, the nav.xhtml gets processed to add kobo spans. A serious question needs to be asked... should it? In theory, the file can be added to the spine to be viewable as part of book content, so probably yes.

Even with the Kobo spans, the spaces *are* preserved, but get filtered out by Kobo when creating it's internal Table of Contents. This is, alas, a bug in the Kobo firmware, but it is only exposed when adding the spans in the TOC file. (Ie, if you rename the original epub to .kepub.epub and copy to the device manually, the TOC preserves spaces properly.)

Edit: As an experiment, I *did* add the nav.xhtml to the spine of book and confirmed that it displays properly with spaces, but the TOC still looses them.

Edit 2: As another experiment, I added a toc.ncx file. But when sending as Kepub, the Kobo still generated it's toc from the nav.xhtml file and did not display the spaces. At this point, I will need to download an epub3 file to Kobo Desktop and decrypt it to see if it handles the nav file differently.