Recommendation ITU-T H.274 specifies the syntax and semantics of video usability information (VUI) parameters and supplemental enhancement information (SEI) messages for use with coded video bitstreams. The VUI parameters and SEI messages defined in this Recommendation may be conveyed within coded video bitstreams in a manner specified in a video coding specification or may be conveyed by other means as determined by the specifications for systems that make use of such coded video bitstreams. This Recommendation is particularly intended for use with coded video bitstreams as specified by Rec. ITU-T H.266 | ISO/IEC 23090-3, although it is drafted in a manner intended to be sufficiently versatile and generic that it may also be used with other types of coded video bitstreams. Revised Rec. ITU-T H.274 adds the specification of nine additional supplemental enhancement information (SEI) messages for coded video bitstreams, and also includes corrections and editorial improvements to various minor defects in the prior content of this Recommendation. The nine additional SEI messages are for annotated regions, alpha channel information, depth representation information, multiview acquisition information, scalability dimension information, extended dependent random access point indication, display orientation, colour transform information, and multiview view position. 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.274 is maintained as technically aligned twin text with ISO/IEC 23002-7.