A cone-of-light projection system projects a shell of laser light using a fiber-optic bundle. The ground dowel receives, in a retaining part, a ground dowel insert part which can be fixed therein and which possesses a retaining means, attached to a baseplate, for determining the position of the beam relative to the ground dowel insert part, the ground dowel insert part being fixed at least adhesively on the pressed-on beam. In the control data region, key information for decoding the encryption of the data information, the physical format information and the optical storage medium manufacturing information are recorded by wobbling a groove. The net may be attached to a material having substantially the size and shape of a license plate.