of the system-model data structure no longer exists,
and a single data structure now caters for both types of arithmetic.
</p>

<p>
The old animation facility relied on a separate program,
called <i>SceneViewer</i>, which was part of an old graphics package
called <i>OpenInventor</i>.&nbsp; A function called <i>drawmodel</i> would
create a text file containing drawing instructions expressed in
OpenInventor's language, and run SceneViewer to display
them.&nbsp; <b><i>Spatial_v2</i></b> comes with a new anima