Techniques to reduce the amount of registration required by a mobile station in a wireless communication system, especially if the registration zones are defined to be small areas. The required depth of field is achieved by using energetic particles to minimize diffraction and an energetic particle source with suitably small diameter. The ball pivot comprises a shaft area and a joint ball, a load-sensing means being arranged in the shaft area of the ball pivot. The first and second icon symbols represent first and second objects, respectively, of a computer program.