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