[TLS] Re: Working Group Last Call for Post-quantum Hybrid ECDHE-MLKEM Key Agreement for TLSv1.3

["Salz, Rich" <[e-mail]>]

  *
Again, this isn't what Recommended=Y/N means in the context
  *
of TLS. Rather, it means that it's generally OK, which is why we have
  *
four separate recommended EC curves.

It seems like it’s worth quoting the meaning as clarified in 8447bis, which is in the RFC editor’s queue. (TL;DR — okay to use, not mandatory to implement)

   Y:  Indicates that the IETF has consensus that the item is
      RECOMMENDED.  This only means that the associated mechanism is fit
      for the purpose for which it was defined.  Careful reading of the
      documentation for the mechanism is necessary to understand the
      applicability of that mechanism.  The IETF could recommend
      mechanisms that have limited applicability, but will provide
      applicability statements that describe any limitations of the
      mechanism or necessary constraints on its use.

   N:  Indicates that the item has not been evaluated by the IETF and
      that the IETF has made no statement about the suitability of the
      associated mechanism.  This does not necessarily mean that the
      mechanism is flawed, only that no consensus exists.  The IETF
      might have consensus to leave an items marked as "N" on the basis
      of its having limited applicability or usage constraints.

   D:  Indicates that the item is discouraged.  This marking could be
      used to identify mechanisms that might result in problems if they
      are used, such as a weak cryptographic algorithm or a mechanism
      that might cause interoperability problems in deployment.  When
      marking a registry entry as “D”, either the References or the
      Comments Column MUST include sufficient information to determine
      why the marking has been applied.  Implementers and users SHOULD
      consult the linked references associated with the item to
      determine the conditions under which the item SHOULD NOT or MUST
      NOT be used.