intended location in the automobile and a fixation knob insertable in the foundation plate and comprising a round base and an arm diagonally opposed to the base and having pressure lugs to rest on the conductor film on its under side facing the base. Here, after attachment of the holding device to an automobile, the conductor film, provided with an oblong hole, or several, can be thrust in between the base and the arm, a finger attached to the arm entering an oblong hole and securing the conductor film against being pulled out. With this holding device, only perforated conductor films can be fastened. DE 88 05 815 U1 shows a clamp for holding of cables which clamp comprises an underpart having a fastening element, opposite the underpartbetween the top part attached to the underpart and opposed to the floor, and the stop arranged on one side of the holding region, which opening is closable by a lid reaching over the top part in closed position and connectable to the underpart by means of a closure. In the clamp formed according to the invention, when the lid is open, several film or tape lines can be introduced successively into the then clear entry opening, these being held securely enough for the performance of assembly operations between top part and underpart and by the lateral stops. When all films or tape lines to be held have been placed in the clamp, the lid is closed, thereby effecting the final fixation of the films or tape lines