This document establishes a reference software for Rec. ITU-T H.266 | ISO/IEC 23090-3.NOTE The use of this reference software is not required for making an implementation of an encoder or decoder in conformance to Rec. ITU-T H.266 | ISO/IEC 23090-3. Requirements established in Rec. ITU-T H.266 | ISO/IEC 23090-3 take precedence over the behaviour of the reference software.