GPS is a subclass of GNSS. And GNSS should be added as a parent class relative to GPS and other GNSS systems listed below.

GNSS stands for Global Navigation Satellite System. It's a general term for any satellite system that uses signals to calculate a receiver's position. GNSS systems provide positioning, navigation, and timing (PNT) services.

It would be good to add the international peers to the U.S. GPS system, Galileo, Beidou, GLONASS, IRNSS, QZSS.

It is significant because in geophysics --> geodesy, GNSS receivers provide more accurate positions because they are multi-constellation (vs GPS only) and therefore can track more satellites at any given time.