The control software also allows automatic distributed operation of {HEAD ~ multiple sites} in {TAIL ~ synchronization} to within parts per million or better 
The control software also allows automatic distributed operation of { HEAD ~ multiple sites } in { TAIL ~ synchronization } to within parts per million or better
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH