The region Boolean executes a simultaneous Boolean intersect and subtract on the involved solids. The typical result contains multiple bodies. In the simplest case, one body represents the result of intersecting the stock and tool solids. Another body represents the result of subtracting the tool solid from the stock solid. Thus, the stock solid is divided into two bodies: one representing the region inside the tool solid and one representing the region outside the tool solid. This is most often used to create a separate body for the purpose of applying a mesh constraint to that subvolume.
Pick the cylinder followed by the box. On the Structure ribbon in the Entity Modification group, click Boolean and choose from the drop-down menu. Click to close the Edit Properties dialog box.
The view now displays the result of the region operation. In the following figure, the newly-created solid is highlighted in red for clarity.
Notice that the region has a presence in the Browser under the Geometry node. The cylinder is located under the Creation > Stocks node and the box is under the Creation > Tools node.