are
<tt>1</tt> for one-bit dither, and <tt>2</tt>, for a 2-bit variable
dot dither.

<dt><b><tt>Aspect:</tt></b><em>{int}</em>
<dd>Controls the aspect ratio for highlight dot placement. Valid
values are <tt>1</tt>, <tt>2</tt>, and <tt>4</tt>. For best results,
choose a value near the x resolution divided by the y resolution. For
example, if resolution is 1440x720, aspect should be 2.

<dt><b><tt>Microdot:</tt></b><em>{int}</em>
<dd>Chooses a microdot size. On EPSON devices, this value is passed
directly thr