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