{TAIL ~ the slot elements} and {HEAD ~ the guide walls} being provided on said port member as flange structure thereon, 
{ TAIL ~ the slot elements } and { HEAD ~ the guide walls } being provided on said port member as flange structure thereon ,
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH