Recommendation ITU-T H.266.1 "Conformance specification for ITU-T H.266 versatile video coding" specifies tests for (non-exhaustive) testing to verify whether bitstreams and decoders meet the normative requirements specified in Rec. ITU‑T H.266 | ISO/IEC 23090-3 Versatile video coding (VVC). The bitstreams provided with this document correspond to the 01/2026 (V3) edition of Rec. ITU-T H.266. Relative to the previous (second) edition, this version adds bitstreams for the Multilayer Main 10 profile. This Recommendation was developed collaboratively with ISO/IEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information, and corresponds with ISO/IEC 23090-15 as technically aligned twin text. The conformance bitstreams needed for this Recommendation are available at: https://www.itu.int/wftp3/av-arch/jvet-site/bitstream_exchange/VVC3rdEd/DIS/