hen no data exists, use <code>TRUE</code>.  If <code>NA</code>, all levels are shown in legend,
but unobserved levels are omitted.</p></dd>


<dt id="arg-show-help">show.help<a class="anchor" aria-label="anchor" href="#arg-show-help"></a></dt>
<dd><p>If <code>TRUE</code>, display some minimal help.</p></dd>


<dt id="arg-inherit">inherit<a class="anchor" aria-label="anchor" href="#arg-inherit"></a></dt>
<dd><p>A logical indicating whether default attributes are inherited.</p></dd>


<dt id="arg-environment"