A multiprocessor digital data processing system comprises a plurality of processing cells arranged in a hierarchy of rings. When the sending element is warmed up and activated by a heater, a microcomputer controls electric power supplied to the heater based on a control base value being set according to a duty ratio100%. The annular gap has a gap width of less than or equal to 20 mm viewed in the cross-section, and the enveloping body has a wall thickness of less than or equal to 20 mm, wherein the plastic is polypropylene, and a separate expansion volume is not provided for the insulating fluid. The upper portion is rotatable relative to the base between a first configuration for supporting the tapered loop antenna element on a horizontal surface and a second configuration for supporting the tapered loop antenna element from a vertical surface. The apparatus provides a device for application of the method for verifying document authenticity.