{HEAD ~ The non extension end edge} of {TAIL ~ each panel} is connected to the opposing panel by flat walls 
{ HEAD ~ The non extension end edge } of { TAIL ~ each panel } is connected to the opposing panel by flat walls
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH