Generically, parameters which apply globally to a particular data transmission, as opposed to the data actually carried in the transmission. These data usually include type of codec, number of channels, channel format, originating node information (in a network context), type of data encryption, etc. In Dolby Digital , metadata specifically refers to the parameters which travel alongside the audio in the Dolby Digital stream as auxiliary data. The metadata here provides scalable decoding information about the audio which can be interpreted in different ways by different receivers, allowing a producer to tailor a program’s mix to the playback environment without requiring the medium to store multiple versions, e.g., a 5.1 mix and a stereo mix.