RTCM Type 1 messages contain pseudorange correction data for GPS satellites. They are used in both the VERIPOS Standard and Standard+ calculations.
RTCM Type 31 messages contain pseudorange correction data for GLONASS satellites. They are used in both the VERIPOS Standard GLONASS and GLONASS Only calculations.
RTCM Type 15 messages contain Ionospheric delay information derived using GPS dual frequency data. They are used in the VERIPOS Standard+ calculation.
RTCM Type 16 messages may be used to broadcast text messages from reference stations to users.
Typically the acceptable age for Type 1 and 31 messages is 120 seconds.
Ionospheric error varies at a slower rate than other errors and so Type 15 messages can be broadcast at a lower rate and ages of up to 600 seconds are acceptable.