I don't know if they got re-classified but I found what I thought was them in Regulations of Equipment of the Army 1942 in Section KA (Misc office Eqpt etc) as Chairs, folding, flat.
However there is no doubting them from the picture in a 1946 VAOS J1 (Camping eqpt) Chairs, G.S.
Although there were fewer slats on the 1946 one. Richard how many slats do yours have?