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