The mask generated from the most significant bits section of the pointer includes {HEAD ~ bits} corresponding to {TAIL ~ various regions} of the output mask 
The mask generated from the most significant bits section of the pointer includes { HEAD ~ bits } corresponding to { TAIL ~ various regions } of the output mask
OTH 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 OTH OTH OTH OTH