data base ;
 block = 1 ; do a = 0 , 1 ;
 do b = 0 , 1 ; do c = 0 , 1 ; do d = 0 , 1 ;
 do e = 0 , 1 ; do f = 0 , 1 ; do g = 0 , 1 ;
        if mod(a+b+c,2) = 0 then
        if mod(a+d+e,2) = 0 then
        if mod(b+d+f,2) = 0 then
        if mod(a+b+d+g,2) = 0 then
           output ;
  end ; end ; end ; end ; end ; end ; end ;
 data foldover ; set base ;
 block = 2 ; a = mod(a+1,2) ;
 b = mod(b+1,2) ; c = mod(c+1,2) ; d = mod(d+1,2) ;
 e = mod(e+1,2) ; f = mod(f+1,2) ; g = mod(g+1,2) ;
 data semifold ; set base foldover ;
 block = 3 ;
 if a = 0 then do ;
    a = 1 ; output ; end ;
 *   Generate some noise data ;
 data comb ; set base foldover semifold ;
 y = normal(33557) ;
 proc glm ;
 class block a b c d e f g ;
 model y = block a b c d e f g a*b a*c
      a*d a*e a*f a*g ; run ;

/****************************************************
                       Sum of
Source           DF   Squares  Mean Square

Model            15     12.78      0.85 Error
12.55      1.56 Corrected Total  23     25.34

   Source   DF Type I SS Type II SS Type III SS

   block     2    2.708      2.252       2.252
   a         1    0.003      0.003       0.003
   b         1    0.792      0.792       1.341
   c         1    1.019      1.019       0.986
   d         1    0.077      0.077       0.053
   e         1    3.083      3.083       1.785
   f         1    0.049      0.049       0.213
   g         1    0.139      0.139       0.028
   a*b       1    0.914      0.914       0.914
   a*c       1    0.015      0.015       0.015
   a*d       1    2.188      2.188       2.188
   a*e       1    0.918      0.918       0.918
   a*f       1    0.576      0.576       0.576
   a*g       1    0.299      0.299       0.299

The fact that the Type I, II, and III sums of squares differ is a
reflection of the non-orthogonality in the irregular 3/32
fraction.
******************************************************************;