@Rick_SAS Thank you! I will find the CALL EXECUTE very helpful in my work!   Below is my code of how to do the proc mixed call. I don't know if you wanted all combinations (e.g. 1 -1 0 0 and -1 1 0 0) or just one (e.g. only -1 1 0 0). If you make it do j = i+1 to 4, then you will get only 1 combination. You can run this even if you don't have a dataset and see the code it writes for SAS to execute.   data test;      length Contrast $ 300;      array a{4} a1 - a4;      /* Initialize array */      do x = 1 to 4;           a{x} = 0;      end;      Contrast = ''; /* This loop will cycle through the array. i controls the +1, j controls the -1. */ /* Contrast will have 12 unique contrasts for the model */      do i = 1 to 4;         a{i} = 1;         do j = 1 to 4;            if i ^= j then do;               a{j} = -1;               do y = 1 to 4;                  Contrast = catx(' ',Contrast,a{y});               end;              call execute (                    "proc mixed data=data1  ; "    ||                    "   class treatment genotype ;"   ||                    " model trait = treatment genotype treatment*genotype / htype=1 ddfm=satterth  ;" ||                    " lsmestimate treatment*genotype '(geno1-geno2)trt1 vs (geno1-geno2)trt2' " ||                    Contrast || ";")               ;               output;               Contrast = '';               a{j} = 0;             end;          end;          a{i} = 0;      end;      keep Contrast; run; ... View more