These tags are considered unregistered for the purpose of this document. From time to time and as required by the community, the IANA may, with the advice and consent of the IESG, create new top-level registration trees. The IANA will only register feature tags in the IETF tree in response to a communication from the IESG stating that a given registration has been approved. Global tags will be registered by the IANA after review by a designated expert. That review will serve to ensure that the tag meets the technical requirements of this specification.
Some fields are optional.
A value of TRUE indicates an available capability. The feature has an associated numeric or enumerated value. 4 Security Considerations Negotiation mechanisms reveal information about one party to other parties. This may raise privacy concerns, and may allow a malicious party to make better guesses about the presence of specific security holes. The authors wish to thank Larry Masinter, Graham Klyne, Al Gilman, Dan Wing, Jacob Palme, and Martin Duerst for their contributions to discussions about media feature tag registration.