I could only find an &quot;overview&quot;, not a full spec: <a href="https:&#x2F;&#x2F;tools.ietf.org&#x2F;html&#x2F;draft-grange-vp9-bitstream-00" rel="nofollow">https:&#x2F;&#x2F;tools.ietf.org&#x2F;html&#x2F;draft-grange-vp9-bitstream-00</a>