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