That would work, up until I actually try to re-zip the contents. Last I looked at the spec, it requires things to be done in a particular order (as @tyingq's li

That would work, up until I actually try to re-zip the contents. Last I looked at the spec, it requires things to be done in a particular order (as @tyingq's link indicates) and although I've used pandoc to convert some other documents, coming up with the proper incantation to feed into it seems like more trouble than just doing it yourself. More to the point, things like my Oral Defense required certain elements to be on a given page (e.g, p.1-2 were front matter and the text began on p.3) and I don't know if that kind of control is possible in pandoc. With regard to validation, there used to be a web form at validator.idpf.org which let you upload a finished book and it would scan for errors, but that page seems to be gone. I don't doubt that epubcheck works, it's just a shame that it requires a huge download to enable its functionality and one which doesn't really play well in macOS. I'm perfectly ok with doing the creation and editing by hand, but come on, this is a UNIX system (!) and the absence of a better command line tool for validating output is imho inexcusable.