Well, that was an interesting foray into the world of ebook editors and readers! Learning a lot in this adventure. The scrambled version is attached. In the course of adding the scrambler, I learned about Calibre, which is required in order to use the scrambler. It also includes an editor as well as its own validator. So now I'm in a version explosion!
But to keep things simple, the version I'm uploading here was generated using Sigil.
Any suggestions appreciated.