program execution.
<p>
<li> `<font color="#82140F"><code>..xinc..</code></font>'
<!-- latex: \index{@code{..xinc..}, x increment on axes} -->
x increment on axes.
<p>
<li> `<font color="#82140F"><code>..xleft..</code></font>'
<!-- latex: \index{@code{..xleft..}, x value at left of plot} -->
x value at left of plot.
<p>
<li> `<font color="#82140F"><code>..xmargin..</code></font>'
<!-- latex: \index{@code{..xmargin..}, left margin} -->
Left margin, in centimetres.
<p>
<li> `<font color="#82140F"><code>..xrigh