Endpoints use the exchange of Setup messages to negotiate MOQT extensions. Extensions can define new Message types, new Parameters, or new framing for Data Streams and Datagrams.
The client and server MUST include all Setup Parameters Section 9.3.1 required for the negotiated MOQT version in CLIENT_SETUP and SERVER_SETUP.
Clients request the use of extensions by specifying Parameters in CLIENT_SETUP. The Server responds with Parameters in the SERVER_SETUP to indicate any extensions it supports.
New versions of MOQT MUST specify which existing extensions can be used with that version. New extensions MUST specify the existing versions with which they can be used.