Specifying a <Polygon>
An instance of the <Polygon> class is required to have 3 or more vertices in counter-clockwise order, specifying a bounded portion of a plane.
However, a <Polygon> may provide more information if desired.
In this terrain example, suppose one of the <Polygon> components of the <Union Of Primitive Geometry> isn't just terrain, but an ECC_TREED_TRACT?
Can we classify that single <Polygon> instance as ECC_TREED_TRACT while leaving the rest of the union as plain ECC_TERRAIN?