You unzip the calibre output and the html was correct?
No, what I said was that I didn't see anything *obviously* wrong there. If you, or others, actually play with Calibre, and assign it real-world "reasonable" tasks, and see the large and interesting variety of ways that it fails, then you will understand my, and others, reluctance to assume that an output from Calibre is representative of anything. http://www.idpf.org/ is the source of the descriptions of what EPUB is and what the file format can and cannot do, if anyone actually cares to try to actually figure it all out. It would be a gift to the PG community if anyone can come up with even a simple tool that reliably takes even one HTML file and correctly and reliably following all the IDPF rules convert that HTML into an EPUB that even begins to work on most EPUB machines. It is NOT as simple as hacking an existing EPUB and inserting your unmangled HTML into the zip file -- as anyone who has tried this approach on non-trivial HTML files has found. Is there already such a tool on the internet? Not that I've found -- and god knows I've gone looking.