What’s the meaning of location classes?

Location classes provide information on the location process and an indication of the location accuracy:

• classes 0, 1, 2, 3 indicate that the location was obtained with 4 messages or more and provides the accuracy estimation,
• class A indicates that the location was obtained with 3 messages,
• class B indicates that the location was obtained with 2 messages,
• class G indicates that the location is a GPS fix obtained by a GPS receiver attached to the platform. The accuracy is better than 100 meters.
• class Z indicates that the location process failed.

The accuracy cannot be estimated for classes A and B (not enough messages).