When the test contactor is in a test position, only one of {HEAD ~ the pair} of {TAIL ~ conductors} is in contact with the test contact member 
of
When the test contactor is in a test position , only one of { HEAD ~ the pair } of { TAIL ~ conductors } is in contact with the test contact member
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH