A substrate assembly for a gas discharge panel, comprising a dielectric layer and a protective layer of MgO being formed in this order on a substrate having electrodes,wherein the dielectric layer is a laminate of an organic dielectric layer and an inorganic dielectric layer in this order from a side of the substrate. If the buffer selected by the transmission controller is detected to have an insufficient occupancy level when selected, a dummy data block is supplied to the data transmission stream in place of a data block from the selected buffer. The invention also includes a device for separating debris from the vacuum airstream. In a third embodiment, the user has to neither download application software, nor register for the service.