This part of IEC 60958-4 specifies the format for coding audio used for the audio content. This is one part of four documents that together specify an interface for the serial digital transmission of two channels of periodically sampled and linearly represented digital audio data from one transmitter to one receiver. It is expected that the audio data will have been sampled at any of the sampling frequencies recognized by the AES5 Recommended Practice for Professional Digital Audio Applications Employing Pulse-Code Modulation Preferred Sampling Frequencies. The capability of the interface to indicate other sample rates does not imply that it is recommended that equipment support these rates. To eliminate doubt, equipment specifications should define supported sampling frequencies.