setgray.ps
%! 50 setlinewidth 100 300 moveto 300 0 rlineto 0.2 setgray stroke 100 400 moveto 300 0 rlineto 0.4 setgray stroke 100 500 moveto 300 0 rlineto 0.6 setgray stroke 100 600 moveto 300 0 rlineto 0.8 setgray stroke showpage