{HEAD ~ Each substrate} has a first edge and {TAIL ~ a second edge} orthogonal with the first edge 
{ HEAD ~ Each substrate } has a first edge and { TAIL ~ a second edge } orthogonal with the first edge
HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH