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