Apple Books data file

I’m making a few assumptions here. I find that the Apple Books app is a little clumsy when it comes to managing books and collections, so I though I’d have a look at going behind its back. It appears that the books are managed in a plist file:

~/Library/Containers/com.apple.BKAgentService/Data/Documents/iBooks/Books/Books.plist

This is an XML file, so it’s easy enough to read. Using XCode, I’ve noticed the following: - The items are mostly books (I have nearly a thousand of them). - There appears to be no section for collections. I gather they’re inferred from the book details. - Books don’t all have the same information. I suppose some items exist for all of the books, but some information is missing from some books. What baffles me most is the collections. There is some information call genre which sort of matches some of the collections, but I can’t work this out. I added two collections and added a book to both, but this doesn’t appear in the plist at all, even after quitting the books app. Maybe it’s the wrong file. Does anybody have any information on managing the books data? __Edit__ Now I’m a little more confused: in the Finder the file appears as an XML file, but in the terminal it’s a binary file.