Upon receiving requests from {TAIL ~ the combination} of {HEAD ~ requesters}, the corresponding priority vector is referred to and the next requester identifier on this list is selected 
Upon receiving requests from { TAIL ~ the combination } of { HEAD ~ requesters } , the corresponding priority vector is referred to and the next requester identifier on this list is selected
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH