The mark consists of a three-dimensional configuration of a film-dispensing cassette having two pairs of generally parallel outer sides, where the outer sides transition in curved corners to form a closed geometrical outline at the outer periphery. The film-dispensing cassette has a ring shape forming a central opening delimited by two pairs of generally parallel inner sides, where the inner sides transition in curved corners to form a closed geometrical outline of the central opening. Dashed lines indicate matter that is not claimed as a feature of the mark. The matter that is not claimed as a feature of the mark includes the three-dimensional configuration of the cassette lid, and a series of vertical ribs on a surface delimiting an inner periphery of a central opening of the cassette.