A method of operating a fuel cell capable of suppressing degradation of a fuel cell caused by starting and stopping of the fuel cell, including carrying out a restoring operation by decreasing a voltage of the cathode following termination of the fuel cell. The punching means has a receiving opening into which a sample card can be introduced by means of a movable gripping unit of the punching device and can be positioned in relation to the punching means, and a punching drive which can be coupled or is coupled to the punch of the punching means and which drives the punch between the resting position and the punching position. A page identifier is the sequence of the first point on its corresponding Hilbert curve section.