Abstract: A document such as an ID-card is provided with check markings comprising a material based upon rare earth metals and having the property that when excited by IR radiation it emits visible light. When checking the document, the document is irradiated with pulsed IR radiation, the occurrence of corresponding visible light pulses originating from said material being detected. The visible light pulses have well defined rise and decay times dictated by the check material used, which fact is used to check that output pulses from the detector are the correct ones for indicating the genuiness of the document.

Abstract: A method of and an apparatus for reading a manually fed data carrier are disclosed. The data carrier has at least one line of coded positions and is fed manually past reader means including at least one pair of reader means which viewed in the direction of motion of the data carrier are spaced apart by a distance less than the extension of a coded position in said direction. Said pair of reader means detects the direction of motion of the data carrier each time a transition between two successive positions passes said reader means. If the detected direction is opposite to the given read-out direction, the count of a counter is increased with one unit. If the detected direction corresponds with the given direction, the count of the counter is reduced with one unit provided that the count exceeds zero. If the direction corresponds with the given direction and the count is zero, read-out result is fed out.