An enforcement mechanism uses the access rights set up for the user to determine whether to grant or deny {HEAD ~ accesses} to {TAIL ~ resources} 
to
An enforcement mechanism uses the access rights set up for the user to determine whether to grant or deny { HEAD ~ accesses } to { TAIL ~ resources }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL