Retention channel 915 extends substantially {HEAD ~ the entire length} along {TAIL ~ each edge} of each part receiving area 910 
Retention channel 915 extends substantially { HEAD ~ the entire length } along { TAIL ~ each edge } of each part receiving area 910
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH