Abstract: Apparatus is disclosed for providing a modulo-n check character as a function of a sequence of data characters. The check character may be used to permit a check of the data character sequence for its correctness, for example, after being transmitted to a data processing installation or after printing. In the preferred embodiments each data character of the sequence is generated by one of a plurality of data character carriers which are selectively set to generate a given character. An additional check carrier is provided to generate the check character. The check carrier is set by a predetermined amount each time one of the data carriers is set so that the ultimately generated check character is a function of the data character sequence.

Abstract: A sensing rod for use in the manual scanning of graphic information. The sensing rod has a tip which is adapted to both reflect light and to receive light which is reflected from an information carrier. A light-emitting section is provided at the front end of the gripping zone which is optically coupled with at least one source of light arranged in the sensing rod.