The retention channel extends substantially an entire length along {HEAD ~ each edge} of {TAIL ~ each part} receiving area 
The retention channel extends substantially an entire length along { HEAD ~ each edge } of { TAIL ~ each part } receiving area
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH