The quality indicator has always been present in GGA messages.
The positioning mode indicator is somewhat similar, but was only added in NMEA 2.3 for the Federal Aviation Administration (FAA).
Quality indicators above 2 are features of NMEA 2.3, or newer:
| Quality | Description |
|---|---|
| 0 | Fix not available |
| 1 | GPS fix |
| 2 | Differential GPS fix |
| 3 | PPS fix |
| 4 | Real-time Kinematics (RTK) |
| 5 | RTK float |
| 6 | Estimated (dead-reckoning) |
| 7 | Manual input |
| 8 | Simulation |