\def\Symbol{{\tt {\char'134}symbol}}
\vbox{\line{\hfil
\diagram{\xaxis3truecm,0.,1.0,0.5,;\noscale
\yaxis4truecm,-1.0,9.0,1.,\Symbol;\nogrid}
{\values{
\symbol0\point0.5,0.0;
\symbol1\point0.5,1.0;
\symbol2\point0.5,2.0;
\symbol3\point0.5,3.0;
\symbol4\point0.5,4.0;
\symbol5\point0.5,5.0;
\symbol6\point0.5,6.0;
\symbol7\point0.5,7.0;
\symbol8\point0.5,8.0;
\symbol9\point0.5,9.0;}}
\hfil
\diagram{\xaxis3truecm,0.,1.0,0.5,;\noscale
\yaxis4truecm,-1.0,9.0,1.,;}
{\values{
\symbol0\point0.5,0.0;
\symbol1\point0.5,1.0;
\symbol2\point0.5,2.0;
\symbol3\point0.5,3.0;
\symbol4\point0.5,4.0;
\symbol5\point0.5,5.0;
\symbol6\point0.5,6.0;
\symbol7\point0.5,7.0;
\symbol8\point0.5,8.0;
\symbol9\point0.5,9.0;}}
\hfil}
\vskip -\medskipamount
\noindent{\bf Figure~13. 
\rm Ten symbols are predefined:
\printsymbol0 = \Symbol{\tt0}, 
\printsymbol1 = \Symbol{\tt1}, 
\dots, 
\printsymbol9 = \Symbol{\tt9}.}}