Is it possible to edit the unlocked map? For example, I would like to add the road number/name to some of the unnamed/unmarked roads. Most of the Japanese roads actually have a name or number, but it's not programmed on the map. The GPS will say "turn left on Road" or "turn left on Trail" for the roads with no name. Would be nice if I could go in and at least add the road number to the map without creating a whole new one.