This enables an engineer to test a telephone line by simply clipping {HEAD ~ a crocodile clip} onto {TAIL ~ the test contact member} and a wall member 
This enables an engineer to test a telephone line by simply clipping { HEAD ~ a crocodile clip } onto { TAIL ~ the test contact member } and a wall member
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH