{HEAD ~ Floor} 44 is formed with {TAIL ~ steps} 46 at an interior edge of opening 45 on which a plate 48 rests, the opening being covered by the plate 
is formed with
{ HEAD ~ Floor } 44 is formed with { TAIL ~ steps } 46 at an interior edge of opening 45 on which a plate 48 rests , the opening being covered by the plate
HEAD HEAD HEAD HEAD HEAD OTH REL REL REL 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