{HEAD ~ The rail portions} of {TAIL ~ the frame} each have an upright outer wall, an integral downwardly slanted inner wall and a hidden outwardly open slot therein between the outer and inner walls 
of
{ HEAD ~ The rail portions } of { TAIL ~ the frame } each have an upright outer wall , an integral downwardly slanted inner wall and a hidden outwardly open slot therein between the outer and inner walls
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH