Sets the Object ID of the clipping entity for this Viewport object (DXF 340).
The following entity types are acceptable clipping entities:
untitled table OdDb2dPolyline OdDb3dPolyline OdDbCircle OdDbEllipse OdDbFace OdDbPolyline OdDbRegion OdDbSpline
A clipping entity must be in the same PaperSpace as this Viewport.