Evo7,
The Garmin GPS units, at least, are based on a split of the world into 3. The Americas, Europe/Africa and Asia/Pacific. Personally, I'd prefer the ability to mix and match smaller regions so I could choose Europe and North America as one. I have dealt with the nice folk at Jeppesen regarding databases and they do offer all sorts of regional/detail choices. It's just that Garmin don't pass those choices on.
BP