DrawingElementRef
DrawingElementRef =
ComponentInstanceRef|ComponentDefinitionRef|ConstructionLineRef|ConstructionPointRef|DimensionLinearRef|DimensionRadialRef|EdgeRef|FaceRef|GroupRef|ImageEntityRef|SectionPlaneRef|SnapRef|TextRef
A reference to a drawing element which may not exist yet.
NOTE: This reference is only valid in the operation that constructed it
SketchupOperation#drawing-element