"ID",Clock Source,Reference
GOES,Geosynchronous Orbit Environment Satellite,[RFC5905]
GPS,Global Position System,[RFC5905]
GAL,Galileo Positioning System,[RFC5905]
PPS,Generic pulse-per-second,[RFC5905]
IRIG,Inter-Range Instrumentation Group,[RFC5905]
WWVB,"LF Radio WWVB Ft. Collins, CO 60 kHz",[RFC5905]
DCF,"LF Radio DCF77 Mainflingen, DE 77.5 kHz",[RFC5905]
HBG,"LF Radio HBG Prangins, HB 75 kHz",[RFC5905]
MSF,"LF Radio MSF Anthorn, UK 60 kHz",[RFC5905]
JJY,"LF Radio JJY Fukushima, JP 40 kHz, Saga, JP 60 kHz",[RFC5905]
LORC,"MF Radio LORAN C station, 100 kHz",[RFC5905]
TDF,"MF Radio Allouis, FR 162 kHz",[RFC5905]
CHU,"HF Radio CHU Ottawa, Ontario",[RFC5905]
WWV,"HF Radio WWV Ft. Collins, CO",[RFC5905]
WWVH,"HF Radio WWVH Kauai, HI",[RFC5905]
NIST,NIST telephone modem,[RFC5905]
ACTS,NIST telephone modem,[RFC5905]
USNO,USNO telephone modem,[RFC5905]
PTB,European telephone modem,[RFC5905]
DFM,UTC(DFM),[DFM_AS][Jščrgen_Appel]