{TAIL ~ A priority vector} for the combination of requesters has a sequential list of {HEAD ~ requester identifiers} 
{ TAIL ~ A priority vector } for the combination of requesters has a sequential list of { HEAD ~ requester identifiers }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD