Electronic labelling system with rail 1 supporting labels fixed onto the edge face of a shelf, the rail and the shelf having the same height, the rail 1 having a free edge 8 and a top groove 9. Optionally, the validation of authorization data may incorporate completion of a financial transaction, this may be effected through use of premium rate telephone lines using the novel method and system of the invention. That process requires capturing a tag of the selected musical item, and processing the tag to develop reference key to the same. The electrical circuit comprises an input circuit for connection to the probe. The alloy layer is effectively protected against re-oxidation by a non-corrosive, alkali metal fluoroaluminate layer which forms simultaneously. A gripper may surround the shaft and prevent improper advancement of the shaft into the face mask.