An electrically extensively heatable, transparent object includes at least one electrically conductive, transparent coating on an electrically insulating substrate. The device also includes a memory for storing a plurality of emergency service connection profiles. =\u03b3m\u03b3FSR with \u03b3FSR=\u03b3mm, determination of the wavelengths of lines in said neighboring order m 1, by means of the provisional wavelength scale \u03b3 1, replacement of the provisional wavelength of at least two lines by the reference wavelength for said lines as obtained in step and repeat of steps to for at least one further neighboring order.