gistfile1.txt

% ------- Define procedures---- 
/inch {72 mul} def
/box % stack: x y => --- 
{ newpath moveto
1 inch 0 rlineto 0 1 inch 
rlineto −1 inch 0 
rlineto closepath } def

/fillbox % stack: grayvalue => --- 
{ setgray fill } def
% ----------- Main Program ----------- 3.5 inch 4.5 inch box
0 fillbox
3.75 inch 5 inch box
.4 fillbox
4 inch 5.5 inch box .8 fillbox showpage