This revised Rec. ITU-T H.266 adds support for the operation range extensions that provide support for higher bit depths, an additional “level 6.3” for support of higher resolutions and bit rates, three new supplemental enhancement information (SEI) messages, and other necessary interface changes corresponding to the revised Rec. ITU-T H.274 V2. This document also includes corrections to various minor defects in the prior content of the Recommendation. This Recommendation was developed jointly with ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information, and Rec. ITU-T H.266 is maintained as technically aligned twin text with ISO/IEC 23090-3.