acter code specifying the perspective (or category by which the population is split into subsets) with 3 options:</p><ol><li><p><code>"cd"</code> ... by condition;</p></li>
<li><p><code>"dc"</code> ... by decision;</p></li>
<li><p><code>"ac"</code> ... by accuracy.</p></li>
</ol></dd>


<dt>area</dt>
<dd><p>A character code specifying the area of the boxes (or their relative sizes) with
3 options:</p><ol><li><p><code>"no"</code> ... all boxes are shown with the same size;</p></li>
<li><p><code>"sq"</code> .