An “execution server” manages requests from client machines based on {HEAD ~ priorities} assigned to {TAIL ~ the requests} 
assigned to
An “ execution server ” manages requests from client machines based on { HEAD ~ priorities } assigned to { TAIL ~ the requests }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL