The apparatus includes {HEAD ~ each timing server} of {TAIL ~ the multiple pluralities} of timing servers configured to transmit, receive, and monitor synchronization signals 
of
The apparatus includes { HEAD ~ each timing server } of { TAIL ~ the multiple pluralities } of timing servers configured to transmit , receive , and monitor synchronization signals
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH