code for determining {TAIL ~ a second set} of candidates from the first set of candidates who have passed {HEAD ~ testing procedures}; and 
code for determining { TAIL ~ a second set } of candidates from the first set of candidates who have passed { HEAD ~ testing procedures } ; and
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH