Apple Bluetooth GPS Protocol

Apple Bluetooth GPS Protocol

Does anyone know where to find reference information on the Apple-specific
protocol for external GPS receives that communicate over Bluetooth?
They're using the proprietary vendor extensions to NMEA-0183 as far as I
can tell, but I would love to get actual specifications.
For example, a Dual XGPS150 will dump out messages such as the following:
0000 50 52 4d 43 2c 30 35 30 36 33 37 2e 30 30 2c 56 PRMC,050637.00,V
0010 2c 2c 2c 2c 2c 2c 2c 32 39 30 39 31 33 2c 2c 2c ,,,,,,,290913,,,
0020 4e 2a 37 41 0d 0a N*7A..
0000 50 56 54 47 2c 2c 2c 2c 2c 2c 2c 2c 2c 4e 2a 33 PVTG,,,,,,,,,N*3
0010 30 0d 0a 0..