A drilling system, including: a drill bit; and a thruster to apply a force to the drill bit. The object of the present invention is to disclose a method for defining reference magnetizations in layer systems, whereby the reference directions can be selected as desired with regard to number and spatial direction. The front portion of the mesh exactly fits into the hernia sac. Certain operating characteristics of a power switching device can be ascertained by analyzing the impedance of the magnetic actuator coil within the power switching device. Light emitted from the light source and incident to the light guide element is diffusion-reflected on the diffusion surface and a part of the diffusion-reflected light illuminates the light-transmissive portion.