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