mix the cut up rhubarb,sugar and orange rind, set aside. sift to-gether the flour, salt and soda. add the oatmeal and mix well to blend. Cream the margarine and brown sugar and add the oatmeal and flour mixture. put half the mixture in a greased 11 x 7 pan, put the rhubarb mixture on top and then the rest of crumbs, press down well so the bars won't be too crumbly. Bake at 200ºC for 35 min.