{HEAD ~ A propped block} 31 is joined to a lower side of {TAIL ~ the connecting block} 3 
{ HEAD ~ A propped block } 31 is joined to a lower side of { TAIL ~ the connecting block } 3
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH