A method for identifying the approximate semantic content of digital objects is disclosed. The tandem OLED device includes a reflective electrode and a transmissive electrode; n organic emissive layers disposed between the reflective electrode and the transmissive electrode, wherein n is an integer equal to or greater than 2; and a connecting unit disposed between every two neighboring organic light emitting layers. This variation is indicative of the sound generated by the musical instrument and can be detected by an electromagnetic radiation detector. Then, when the stopper rod is opened, molten metal flows from the pour box through the nozzle and into the mold. In response to receiving data indicating that the parameter has been acquired by said second device, the interface processor updates the message data for communication to the second device to indicate additional data is unavailable for acquisition.