ont color="#82140F">
.offset. = {rpn ..ysize.. 3 + }
open file1
read columns x y
close
draw axes
draw curve 
<p>
..ymargin.. += .offset.
open file2
read columns x y
draw axes 
draw curve 
close
<p>
..ymargin.. += .offset.  
open file3 
read columns x y 
draw axes 
draw curve 
close
</font></PRE>
</TD>
</TR>
</TABLE>
<p>
The first line needs a bit of explanation. It is a reverse-polish
expression.  The format is `<font color="#82140F"><code>{</code></font>' followed by `<font color="#82140F"><code>rpn</code>