Is this expected behavior? Sometimes books don't include identifiers, such as compilations of classics, sold by several sites.
If I include one, such as uri:
http://www.website.com/book_name, the GUI shows it. However, if I polish the book to put the identifier into the file so I can export it and store it somewhere apart from Calibre (I know Calibre can update metadata when exporting, but I have this option disabled), the identifier does not end up in the OPF-file.
Is this as it is supposed to be, or is this a bug?