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.

The summary of the review is Ready


The document clarifies the usage of an existing flag, and adds new flag
that fine-tunes the interpretation of the original flag. the document does 
not introduce any new security concerns.