The plug board may provide {HEAD ~ a rib} in {TAIL ~ both top and back surfaces} thereof, while the upper and lower housings each provides a groove to receive the rib in the plug board 
in
The plug board may provide { HEAD ~ a rib } in { TAIL ~ both top and back surfaces } thereof , while the upper and lower housings each provides a groove to receive the rib in the plug board
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH