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<h1>Viewports</h1>
<p>
Viewports are workspaces where the graphical objects are placed. 
For the stand alone usage of DoNaLD, viewport should not be defined. 
Since <a href="../scout/index.html">Scout</a>, a definitive
notation for describing screen layout, has the ability to show different
pictures in different (Scout) windows, when DoNaLD is used in
conjunction with Scout, viewport is a useful way of separating objects
into different pictures.  In DoNaLD, the line:
</p>
<pre>viewport VIEW1</pre>
<p>
means that from that line onwards the graphical objects to be
declared (not defined) will be associated with the viewport VIEW1.  All
viewports share the same conceptual space, and variables in one viewport
can freely make reference to variables in other viewports.  Viewports
need not be displayed.  Hence it is useful to dump intermediate or
conceptual objects into a viewport which will not be displayed.
</p>
<p>
For backward compatibility, declaring DoNaLD variables without first
declaring a viewport will create a default viewport displaying on a
separate screen.  This default viewport is named as <code>DoNaLD</code>.
</p>

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