Part 3 of the MPEG-2 standard (formally known as ISO/IEC 13818-3, also known as MPEG-2 Audio or MPEG-2 BC) defines audio coding: The MPEG-2 Part 3 should not be confused with MPEG-2 Part 7: AAC a.k.a.
MPEG-2 NBC (Non-Backward Compatible) - the MPEG-2 Advanced Audio Coding with support for multichannel encoding (up to 48 channels).
[1][2] MPEG-2 Part 3 introduced new audio encoding methods compared to MPEG-1 Part 3:[7] MPEG-2 BC (backward compatible with MPEG-1 audio formats)[1][2][5]