An invalidation scheme of a secret key is implemented, which is usable for a functional encryption scheme. The method records events performed at the same time respectively by an event field, and also the event fields correspond to a time field, such that a musical file can have less file length. Alternatively, the protective film is formed by laminating a plurality of resin films which differ in one of the water absorption ratio, the elastic modulus and the hardness. The base unit communicates status information regarding the appliance to the receiving unit and the receiving unit can determine whether the status of the appliance is undesirable. Player excitement and enjoyment is enhanced because the present invention provides the player with multiple opportunities to achieve game credits and because the player is guaranteed to have at least one opportunity to select from the final selection group.