Comment 9 for bug 1012243

Minimal metadata – author, title, genre – are extracted from the OPF file by iTunes when adding a book. All other metadata fields can only be added or edited manually by the user in iTunes, or through the OSA interface.

Calibre's UDID for the book is stored in the 'composer' field, which was selected because it's one of the few fields which can be searched through the iTunes OSA interface. There's no way that I'm aware of to put something in the OPF file that iTunes would subsequently discover and place into the composer field in its database. That's the tip of the iceberg. The rest of the lesser-used metadata - sort fields, series #s, comments, etc - also need a means of finding their way into the iTunes database.

To simplify, the driver as implemented sends the book to iTunes. Once the book has been added to iTunes, calibre then tweaks the metadata according to the user's options.

Without OSA communication, it's possible to get the book to iTunes, but once it's there, there's no way to update the metadata or delete the book.