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