Abstract: An imitation-proof card-like data carrier which permits light to pass through a large number of light-conducting elements each having a light-admitting inlet portion, a light-discharging outlet portion which is laterally offset relative to the inlet portion, and a light-conducting intermediate portion with two reflecting surfaces, one adjacent to the inlet portion and the other adjacent to the outlet portion. The information which is stored in or denoted by an element is characterized by the distance beween the inlet and outlet portions as well as on the inclination of that reflecting surface which directs light into the outlet portion. The light rays issuing from the outlet portions of the elements impinge upon selected photodiodes of an array of photodiodes in an apparatus into which the data carrier is inserted to ascertain the genuineness thereof, to ascertain the identity of the bearer, to cancel certain elements if each element represents a sum of money and/or for other purposes.