Abstract: The invention relates to a method for opening doors, safety apparatus and the like, and to an electronic control device in which at least two cards are employed. Each card is provided with identifying elements, which are arranged in the same manner as in the other cards. One card has to be inserted in the internal part of a reading unit which is mounted on the system to be controlled, this card being thus provided with hte combination for the system itself. The other card may be inserted in a further reading unit which is identical with the first one and is accessible from the outside. If identical reading combinations are detected on comparing both series of identifying elements, positioned on the movable cards in an identical manner, a consent signal is emitted for actuating the opening mechanism.