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