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