></font>', which do conversion between points and
centimetres, are often useful in labelling data curves 
(see <a href="ReversePolishMath.html#rpnMathematics">rpn Mathematics</a>).
<p>
<li> `<font color="#82140F"><code>..graylevel..</code></font>'
<!-- latex: \index{@code{..graylevel..}, graylevel (0=black)} -->
Graylevel to use in drawing lines, text, etc.  Black ink is 0; white
paper is 1.  <b>See also</b> `<font color="#82140F"><code>..red..</code></font>' etc.
<p>
<li> `<font color="#82140F"><code>..ima