%% 
%%  Ein Beispiel der DANTE-Edition
%%  
%%  2. Auflage
%% 
%%  Beispiel 15-02-33 auf Seite 729.
%% 
%%  Copyright (C) 2016 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.
%% 
%% 
%% ==== 
verbatimtex
%% 
\documentclass[]{article}
\usepackage[T1]{fontenc}
\begin{document}
etex
% --- start of displayed preamble in the book ---
input boxes;
% --- end of displayed preamble in the book ---
beginfig(1)
fill unitsquare xscaled 1.1in yscaled .7in
	withcolor 0.9white;
boxit(currentpicture);
dx=dy=10mm; clearit; drawboxed();
forsuffixes $=n,c: makelabel.top(str $,$); endfor;
makelabel.bot("s",s);
forsuffixes $=ne,e,se: makelabel.rt(str $,$); endfor;
forsuffixes $=nw,w,sw: makelabel.lft(str $,$); endfor;
pickup pencircle scaled .3bp;
vardef larrow@#(expr a,da,s)=
  drawdblarrow a..a+da; label@#(s,a+.5da); enddef;
larrow.rt(n,(0,-dy),"dy"); larrow.rt(s,(0,dy),"dy");
larrow.top(e,(-dx,0),"dx");larrow.top(w,(dx,0),"dx");
endfig;
end;
\end{document}
