Abstract: A method of providing by a laser beam on a bright metal surface (1) areas discernible from the surrounding surface as darker areas for producing for instance optically readable marks (5) and a metal surface provided in this manner. The procedure for producing marks not weakening the general properties of the metal surface is that the metal surface (1) is exposed to a laser beam pulse, the energy of which is 1 to 10 J/cm.sup.2, preferably 3 to 5 J/cm.sup.2 and the duration 5 ns to 1 .mu.s, preferably 15 to 30 ns; a spot of impact (7) of the laser beam pulse on the metal surface (1) is changed in such a way that a new spot of impact (8) overlaps the earlier spot of impact (7) and the metal surface (1) is exposed to a new laser beam pulse, such that an area (7a) of the metal surface, where the pulses do not overlap each other and which abuts on the spot of impact of the new pulse, gets a color contrasting with the original metal surface (1).

Abstract: A location scale and an optical reading sensor for reading the location scale. The location scale comprises bars with a first edge and a second edge, wherein either the first edges or the second edges are located at regular intervals to form an incremental scale. To provide both incremental data and absolute data on the same scale, the bars are of at least two different widths, and any n successive bars on the scale form a unique individual code indicating the absolute location of those n bars on the scale.