An arbitration method and {HEAD ~ mechanism} assigning {TAIL ~ priority} to one of a combination of requesters 
assigning
An arbitration method and { HEAD ~ mechanism } assigning { TAIL ~ priority } to one of a combination of requesters
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH