constructive solid geometry NeXus class, using :ref:`NXquadric` and :ref:`NXoff_geometry`. One of the standard construction solid geometry set operations, or if the CSG is a pointer to the geometry provided by an :ref:`NXquadric` or an :ref:`NXoff_geometry`. Takes values: The first operand of constructive solid geometry operation. Compulsory if 'operation' is UNION, INTERSECTION, DIFFERENCE or COMPLEMENT. The second operand of constructive solid geometry operation. Compulsory if 'operation' is UNION, INTERSECTION or DIFFERENCE. Path to a field that is either an :ref:`NXquadric` (if 'operation' = IS_QUADRIC) or an :ref:`NXoff_geometry` (if 'operation' = IS_MESH) that defines the surface making up the constructive solid geometry component. Compulsory if 'operation' is IS_QUADRIC or IS_MESH.