Similarly, {HEAD ~ a memory access} refers to either a memory read or {TAIL ~ a memory write operation} 
Similarly , { HEAD ~ a memory access } refers to either a memory read or { TAIL ~ a memory write operation }
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL