"Peter" wrote in message ...

"John R. Copeland" wrote

How does Garmin prevent people sharing data on e.g. the MX20/GNS480,
when the flash cards are standard FAT?

Garmin doesn't.
Jeppesen does it by managing the subscription services.

OK, so if a bunch of GNS480 owners get together, they can copy the CF
data cartridges and share them? That's pretty good - essential here in
Europe where we pay some USD3000+ for European Jeppview

Someone in that bunch will need to be a skilled hacker, though.
There are license keys involved.
Furthermore, the MX20 and GNS480 keys are handled differently.