Arbiter 16 receives requests for {TAIL ~ access} from any of a number of {HEAD ~ requesters} 
Arbiter 16 receives requests for { TAIL ~ access } from any of a number of { HEAD ~ requesters }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD