Section Cut is a Thea Render entity that allows the users to cut parts from his scene. It is defined as a plane and it is added transparently into the active camera. To add a Section cut in your scene, create a Plane primitive object and add the Thea Section Cut Tag. The plane's Y axis shows which part of the scene will be invisible from your rendering. Since only the matrix is needed to define a section cut, instead of just a primitive, any object can be used as section cut, but it is preferable to use Planes since it makes it easier to visualize the section cut in the viewport.
Last, Thea supports multiple Section cuts in the same scene and all of them are added in the active camera.