Earlier quoted context omitted.
For the limits the speed is 1200 mph and the altitude 59,000 ft. A commercial airliner won’t exceed 650 mph or 40,000 ft.
I think those are the old COCOM limits which are no longer in effect. I believe that currently the only limit is 600 m/s (which is nice, since when there were both speed and altitude limits some manufacturers OR'd them and some manufacturers AND'd them, so it wasn't clear if altitude alone would be enough to disable a device until you found out the hard way)
Ah, yeah that's been updated since I've worked with GPS