IEC 61937-11:2021 is available as IEC 61937-11:2021 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.

IEC 61937-11:2021 describes the method to convey non-linear PCM bitstreams encoded in accordance with the MPEG-4 AAC format and its extensions (spectral band replication, parametric stereo and MPEG surround), and non-linear PCM bitstreams encoded in accordance with the MPEG-D USAC format, framed in MPEG-4 LATM/LOAS. IEC 61937-11:2021 cancels and replaces the first edition published in 2010, and Amendment 1:2018. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) MPEG-D USAC has been added.