Sorry in advance for what is I am sure a frequent question. I was unable to find a clear answer, but no doubt this is due to poor searching on my part...
I finally found some time to try out Calibre. I find that it immediately solved one huge problem I've had with the Opus, which is that it has no margin on the screen, making many ebooks hard to read. Running the books through Calibre to add a margin turns out to be trivial. Thanks kovidgoyal!
Where I'm running into problems is that when I do a transfer to device, Calibre wants to put everything into a relatively flat folder structure (i.e., one folder per author.) Since the Opus doesn't have categories, I had hoped to be able to group the files into folders on the Opus, first by topic, then by author. Other than manually, is there any way of directing Calibre to transfer books to a particular folder on the Opus?
(Please note that I am
not asking
that question. I couldn't care less how Calibre represents files internally. I'm only talking about the layout used when the files are transferred to the device.)