In parallel, {HEAD ~ a network based clock offset} between the two clocks can be calculated based on messages exchanged over {TAIL ~ a communication network} interconnecting the two clocks, without reverting to the global time reference 
In parallel , { HEAD ~ a network based clock offset } between the two clocks can be calculated based on messages exchanged over { TAIL ~ a communication network } interconnecting the two clocks , without reverting to the global time reference
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH