A safety device for the throttle operation includes a shaft, a linking plate having an end connected and moving with the shaft and another end provided with an projecting bent wing, a pulling plate having one end formed with a shaft hole for combining with the shaft and located at a side of the bent wing and another end resting on an end surface of the bent wing and connected with a throttle line. A user-defined metalabel is assigned to each of the electronic files, web pages, or web site members. Present invention further provides a 300% increase in average encoding rate and better implementation of stego-keys is achieved over previous MIDI steganography methods.