\def\yaxIs{\ifnum\yscaling=1\raise\ynumbering%
\hbox to\xpos{\advance\ylength\ht2%
\vbox to\ylength{\xfinal0\yfinal0%
\ifnum\ybasis=10\else\message{ynumber-Error!}\fi%
\divide\ymin\ybasis\divide\ymax\ybasis%
\divide\yinc\ybasis%
\loop\advance\xfinal1\xvalint\ymin%
\setbox\xfinal\hbox to\xpos{\hfill%
\ifnum\xvalint<0-\xvalint-\xvalint\fi\relax%
\number\xvalint\kern.5\em}%
\advance\ymin\yinc\ifnum\ymin>\ymax%
\yfinal1\fi\relax\ifnum\yfinal=0\repeat%
\loop\box\xfinal\negadvAnce\xfinal1\relax%
\ifnum\xfinal>0\vss\repeat}}\kern-\xpos\fi}%