{HEAD ~ One flange} 46 has a depending lip 48 and the other flange 47 has {TAIL ~ an upstanding rib} 49 to seat within the channel flanges 40 securing the tray from downward movement 
{ HEAD ~ One flange } 46 has a depending lip 48 and the other flange 47 has { TAIL ~ an upstanding rib } 49 to seat within the channel flanges 40 securing the tray from downward movement
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH