{HEAD ~ The pair} of stacks is connected by {TAIL ~ a length} of material which is folded on top of the stacks 
{ HEAD ~ The pair } of stacks is connected by { TAIL ~ a length } of material which is folded on top of the stacks
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH