said slot elements including {TAIL ~ respective guide walls} disposed in {HEAD ~ parallel opposition} to said port member and slidably engaged by the corresponding tongue elements, 
said slot elements including { TAIL ~ respective guide walls } disposed in { HEAD ~ parallel opposition } to said port member and slidably engaged by the corresponding tongue elements ,
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH