{HEAD ~ Each} of the side rail portions of the frame has {TAIL ~ an upright outer wall} and an integral horizontal top wall merging into an inwardly and downwardly slanted inner wall 
has
{ HEAD ~ Each } of the side rail portions of the frame has { TAIL ~ an upright outer wall } and an integral horizontal top wall merging into an inwardly and downwardly slanted inner wall
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH