IEC 61937-7:2004 specifies the method for the digital audio interface specified in IEC 60958 to convey non-linear PCM bitstreams encoded in accordance with the ATRAC, ATRAC2/3 and ATRAC-X formats. This second edition cancels and replaces the first edition published in 2002. It constitutes a technical revision. This edition includes the following significant technical changes: In this edition, a new audio data-type of ATRAC-X is added to ATRAC and ATRAC2/3. Specific properties such as reference points, repetition period, the method of filling stream gaps, and decoding latency are specified for data-type of ATRAC-X.