%% 
%%  A DANTE-Edition example
%% 
%%  Example 02-03-1 on page 22.
%% 
%%  Copyright (C) 2010 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{article}
\pagestyle{empty}
\setlength\textwidth{129.70511pt}
\setlength\parindent{0pt}

\usepackage{pstricks}

\begin{document}
\psframebox[framesep=0pt,linestyle=dotted]{%
\begin{pspicture}(2,1)% cm is default
  \psset{xunit=0.5mm,yunit=2mm}
  \psline{->}(40,5)\psline{->}(0,1cm)(40,0)
\end{pspicture}}\\[20pt]
\psset{xunit=0.5mm,yunit=2mm}% changes the default!
\psframebox[framesep=0pt,linestyle=dotted]{%
\begin{pspicture}(40,5)% default for x and y is different
  \psline{->}(40,5)\psline{->}(0,1cm)(40,0)
\end{pspicture}}
\end{document}