Draft:  
Reviewer: 
Review Date:
Review Deadline: 
Status: Expert Review 

Review Summary: 


Expert Evaluation (per RFC 3427):
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    1.  A designated expert (as defined in RFC 2434 [4]) MUST review the
        proposal for applicability to SIP and conformance to these
        guidelines.  The Expert Reviewer will send email to the Transport
        Area Directors on this determination.  The expert reviewer can
        cite one or more of the guidelines that haven't been followed in
        his/her opinion.

    2.  The proposed extension MUST NOT define SIP option tags, response
        codes, or methods.

    3.  The function of the proposed header MUST NOT overlap with current
        or planned chartered extensions.

    4.  The proposed header MUST be of a purely informational nature, and
        MUST NOT significantly change the behavior of SIP entities which
        support it.  Headers which merely provide additional information
        pertinent to a request or a response are acceptable.  If the
        headers redefine or contradict normative behavior defined in
        standards track SIP specifications, that is what is meant by
        significantly different behavior.

    5.  The proposed header MUST NOT undermine SIP security in any sense.
        The Internet Draft proposing the new header MUST address security
        issues in detail as if it were a Standards Track document.  Note
        that, if the intended application scenario makes certain
        assumptions regarding security, the security considerations only
        need to meet the intended application scenario rather than the
        general Internet case.  In any case, security issues need to be
        discussed for arbitrary usage scenarios (including the general
        Internet case).

    6.  The proposed header MUST be clearly documented in an (Individual
        or Working Group) Informational RFC, and registered with IANA.

    7.  An applicability statement in the Informational RFC MUST clearly
        document the useful scope of the proposal, and explain its
        limitations and why it is not suitable for the general use of SIP
        in the Internet.


Comments:
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Nits:
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