<b>pic</b> objects</p>

<p style="margin-top: 1em">The missing simple object type
is a <i>spline</i>. There is also a way to collect objects
into <i>block composites</i> which allows you to treat the
whole group as a single object (resembling a box) for many
purposes. We&rsquo;ll describe both of these later on.</p>

<p style="margin-top: 1em">The box, ellipse, circle, and
block composite objects are <i>closed</i>; lines, arrows,
arcs and splines are <i>open</i>. This distinction is often
important in expla