can I add tags to the book's filename?
I know I can do it when «saving to disk».
I just would like to have them into the library to.
As a matter of fact, I would prefer not to save to disk every book.
I would like to keep and sync the library with PDF Expert or iBooks into my iDevices, where then I could search for a particular tag (I prepend the hashtag symbol to every tag, so that searching is more accurate).
Is there a way to do that? I know you cannot change the dir structure of the library, but what about file names?