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 provides a guide to the many specifications related to SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions). The document is quite useful for people like me who know little about SIMPLE and would like to get a quick overview. Bravo to the authors! The Security Considerations section of the document states that "This specification is an overview of existing specifications, and does not introduce any security considerations on its own." I agree. I did notice one thing that may be a typo. Section 3.2 says: RFC 4975, The Message Session Relay Protocol (MSRP) (S): [RFC4975] defines a small text-based protocol for exchanging arbitrarily sized content of any time between users. I don't understand the words "of any time". Maybe they're supposed to say "of any kind"? Or "at any time"? Not a big deal but the text is confusing. Other than that little glitch, I think the document is ready to go. Thanks, Steve