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