I created an epub framework in InDesign, exported it as a book, then opened it with BBEdit so I could import my html files.
It's working great, except that break tags trigger errors. I got another error message for the entity nbsp. (I'm previewing it with iBooks.)
So I'm trying to figure out what's going on here. Are break tags and white space not allowed in epubs? If so, is there another protocol for inserting breaks and white space?