Hacking my way through various operations, trying to root out "unavailable font" messages, and I've noticed (not for the first time, but for the first time I've been minded to ask questions) a whole slew of paragraph style definitions in the .book. Even if I assume they've drifted in there from the component .fm files, I'm still left wondering why.
And considering I've just exposed one area of ignorance, let's go for broke with another question: what is encoded in the BookFileInfo block?