They occur at {HEAD ~ precise times} in {TAIL ~ programming} and can synchronize the operation of receiver station apparatus to the timing of programming transmissions 
in
They occur at { HEAD ~ precise times } in { TAIL ~ programming } and can synchronize the operation of receiver station apparatus to the timing of programming transmissions
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH