A:Answer It means that you must plug either a USB extension or another type of cable, lightning, etc... to extend it forward so that you can plug something in, elsewhere, since the back of the deck will not be accessible. I would not put a flash drive directly in the back. In some cases it may not even fit, but I've had multiple decks that get a read error and the flash drive needs to be unplugged and plugged back in, so a USB extension is recommended.
