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4.6. Specification Required

4.6. Specification Required​

For the Specification Required policy, review and approval by a designated expert (see Section 5) is required, and the values and their meanings must be documented in a permanent and readily available public specification, in sufficient detail so that interoperability between independent implementations is possible. This policy is the same as Expert Review, with the additional requirement of a formal public specification. In addition to the normal review of such a request, the designated expert will review the public specification and evaluate whether it is sufficiently stable and permanent, and sufficiently clear and technically sound to allow interoperable implementations.

The intention behind "permanent and readily available" is that a document can reasonably be expected to be findable and retrievable long after IANA assignment of the requested value. Publication of an RFC is an ideal means of achieving this requirement, but Specification Required is intended to also cover the case of a document published outside of the RFC path, including informal documentation.

For RFC publication, formal review by the designated expert is still requested, but the normal RFC review process is expected to provide the necessary review for interoperability. The designated expert's review is still important, but it's equally important to note that when there is IETF consensus, the expert can sometimes be "in the rough" (see also the last paragraph of Section 5.4).

As with Expert Review (Section 4.5), clear guidance to the designated expert should be provided when defining the registry, and thorough understanding of Section 5 is important.

When specifying this policy, just use the term "Specification Required". Some specifications have chosen to refer to it as "Expert Review with Specification Required", and that only causes confusion.

Examples:

  • Diffserv-aware TE Bandwidth Constraints Model Identifiers [RFC4124]
  • TLS ClientCertificateType Identifiers 64-223 [RFC5246]
  • ROHC Profile Identifiers [RFC5795]
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