nt></p>


<p align="center" style="margin-top: 1em"><font color="#000000">Figure
11-3: Composite block objects always have positive width and
height</font></p>

<p style="margin-top: 1em"><font color="#000000">Blocks may
be nested. This means you can use block attachment points to
build up complex diagrams hierarchically, from the inside
out. Note that <b>last</b> and the other sequential naming
mechanisms don&rsquo;t look inside blocks, so if you have a
program that looks like</font></p>

<pre style="margi