I have reviewed this document as part of the security directorate's
ongoing effort to review all IETF documents being processed by the IESG.
These comments were written primarily for the benefit of the security area
directors.  Document editors and WG chairs should treat these comments
just like any other last call comments.

This document describes a mechanism to prevent extensibility failures in
the TLS ecosystem.  It reserves a set of TLS protocol values that may be
advertised to ensure peers correctly handle unknown values. Aside from a
nit/question, the document is ready.

The question relates to language in section 2. which states: "The values
allocated above are thus no longer available for use as TLS or DTLS
[RFC6347] version numbers." Should this draft be marked as updating 6347
and 8446 as a result? At present it is Informational and does not update
any other specifications.