This invention relates to coextruded, transparent, biaxially oriented polyester film comprising a base layer and a heatsealable top layer which is peelable from at least APET, the heatsealable and peelable top layer consisting ofa) 80-98% by weight of polyester andb) 2-10% by weight of inorganic andor organic particles having an average diameter d50 of from 2. The stacked layers form signal processing components and at least one peripheral wall surrounding a walled area of each substrate. The second processor module includes a second microprocessor and memory. The purge gas supply system includes a purge gas mixture generator configured to generate a purge gas mixture which includes at least one purging gas and moisture. A new service can be started only if the control characteristics it requires are not reserved by a previously invoked service. In one embodiment, the nitride compound includes SixNy.