Furuno FCR-2107 Series Operator's Manual page 512

Appendix 5: Digital Interface
RMC - Recommended minimum specific GPS/TRANSIT data
Recipient of sentences:
Expected nominal interval of sentences: 1 - 5 s
Alarm generated if message not received: 22 s ± 2 s
E = Estimated (dead reckoning)
M = Manual input
S = Simulator
N = data not valid
ROT – Rate of turn
Recipient of sentences:
Expected nominal interval of sentences: 1 s
Alarm generated if message not received: 12 s ± 2 s
AP-60