Regions are 2D enclosed areas you create from closed shapes called loops. A loop is a curve or a sequence of connected curves that defines an area on a plane with a boundary that does not intersect itself. Loops can be combinations of lines, polylines, circles, arcs, ellipses, elliptical arcs, splines, 3D faces, traces, and solids. The objects that make up the loops must either be closed or form closed areas by sharing endpoints with other objects. The objects must also be coplanar (on the same plane).
