A method of manufacturing a telephony earpiece is provided. A heating heat exchanger provided to heat a vehicle passenger compartment is arranged in a coolant circuit of the fuel cell system, and is externally heated, at least at times, by the burner. The local computer runs a computer program adapted to the instrument or instruments controlled by that panel module, so that the local computer communicates with the data bus for bi-directional communication between the instrument and the control computer. The OTC track pitch is measured with a 747 curve, and the ATI track pitch is measured by the positions of adjacent tracks at which the on-track error rate is not worse than a given value after the targeted number of adjacent track writes in the ATI requirement. When the operating portion is pushed inward, the bias portion displaces inward correspondingly and disengages from the stop grooves. Z1 and Z2 are independently selected from CH and N.