Quick Reference :: PostScript Language
Operator:
[
a b c d ...
]
w
setdash
sets the dash pattern parameter
Example :
%! newpath 100 700 translate 0 0 moveto [8 8] 0 setdash 400 0 rlineto stroke 0 -100 moveto [] 0 setdash 400 0 rlineto stroke showpage