measuring characteristics of a subset of {HEAD ~ said plurality} of {TAIL ~ processing regions}, defining measured characteristics 
of
measuring characteristics of a subset of { HEAD ~ said plurality } of { TAIL ~ processing regions } , defining measured characteristics
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH