options nocenter nodate;

data one;
  input yield fert variety $;
  cards;
134  5 A
140 10 A
146 15 A
153 20 A
138  5 B
142 10 B
145 15 B
147 20 B
;

data two; set one;
  y=yield;
  x1=fert;
  if variety='A' then x2=1;
  else x2=0;
  x3=x1*x2;
run;

proc print;
run;

proc reg;
  model y=x1 x2 x3;
run;

proc glm;
  model y=x1 x2 x3;
  estimate 'Variety A intercept' intercept 1 x2 1;
  estimate 'Variety A slope' x1 1 x3 1;
  estimate 'Variety B intercept' intercept 1;
  estimate 'Variety B slope' x1 1;
run;

data three;
  input yield fert variety $;
  cards;
134  5 A
140 10 A
146 15 A
153 20 A
138  5 B
142 10 B
145 15 B
147 20 B
137  5 C
144 10 C
150 15 C
158 20 C
;

data four; set three;
  y=yield;
  x1=fert;
  if variety='A' then x2=1;
  else x2=0;
  if variety='B' then x3=1;
  else x3=0;
  x4=x1*x2;
  x5=x1*x3;
run;

proc print;
run;

proc reg;
  model y=x1 x2 x3 x4 x5;
run;

proc glm;
 model y=x1 x2 x3 x4 x5;
 estimate 'Variety A intercept' intercept 1 x2 1;
 estimate 'Variety A slope' x1 1 x4 1;
 estimate 'Variety B intercept' intercept 1 x3 1;
 estimate 'Variety B slope' x1 1 x5 1;
 estimate 'Variety C intercept' intercept 1;
 estimate 'Variety C slope' x1 1;
run;

proc glm;
  model y=x1 x2 x3 x5;
 estimate 'Variety A intercept' intercept 1 x2 1;
 estimate 'Variety A slope' x1 1;
 estimate 'Variety B intercept' intercept 1 x3 1;
 estimate 'Variety B slope' x1 1 x5 1;
 estimate 'Variety C intercept' intercept 1;
 estimate 'Variety C slope' x1 1;
run;