At the upper position, the tabletop units 32 are separated and {HEAD ~ the brace portions} 38 and 40 are disposed in substantially axial alignment or in {TAIL ~ substantially a straight line}, and the tabletop units 32 are at higher tabletop position 
are disposed in
At the upper position , the tabletop units 32 are separated and { HEAD ~ the brace portions } 38 and 40 are disposed in substantially axial alignment or in { TAIL ~ substantially a straight line } , and the tabletop units 32 are at higher tabletop position
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH