Hello,   I need to control the order of the variables in a given data set and use RETAIN before the SET statement. Here is an example:     data start ; var1 = 1 ; var2 = 2 ; output ; var1 = . ; var2 = 2 ; output ; run ; data end ; retain var2 var1 dummy ; set start ; if var1 = 1 then dummy = 1 ; run ; I have done this dozens of times in the past but now I encountered a problem. The resulting data set looks like that:     var2 var1 dummy 1 2 1 1 2 2 . 1   I expected dummy in row 2 to be a missing. To me it seems that dummy is retained although I only used RETAIN to order the columns which should have no effect on the values of the variable itself according to this source. Can anybody explain this to me?   ... View more