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