{TAIL ~ The at least one cross member} is terminated on each end by {HEAD ~ a single side support member} 
{ TAIL ~ The at least one cross member } is terminated on each end by { HEAD ~ a single side support member }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD