Modified regions

When you modify regions in your CAD application, do not leave a region with a hole. You cannot select a region by clicking inside a hole.

In your CAD application, you can modify regions with the union, subtract, and intersect operations. When you use the subtract operation on overlapping regions, the operation subtracts the inner boundary area from the outer boundary area. In this case, the subtract operation leaves a region with a hole. To account for the area of this hole, you can draw a boundary, typically a polyline, around the hole. You can then assign a boundary to the polyline.