Each L shaped leg 34 includes a transversely extending lip 38 with {HEAD ~ a keying arrangement} in {TAIL ~ the form} of a plurality of slots 40 formed therein 
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Each L shaped leg 34 includes a transversely extending lip 38 with { HEAD ~ a keying arrangement } in { TAIL ~ the form } of a plurality of slots 40 formed therein
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH