I am an assigned INT directorate reviewer for . These comments were written primarily for the benefit of the Internet Area Directors. Document editors and shepherd(s) should treat these comments just like they would treat comments from any other IETF contributors and resolve them along with any other Last Call comments that have been received. For more details on the INT Directorate, see https://datatracker.ietf.org/group/intdir/about/ . This draft defines a few optional extensions to the LoST protocol as defined in RFC5222 so that the server can provide supplemental information that may be useful for the client. I'm not familiar with the LoST protocol, so it's quite possible my review miss something. With noting that, the draft is very well written, its purpose and explanations are clear, and I didn't find any obvious problem, especially those related to the INT area. I think it's ready for publication. I have a couple of comments, making mostly just out of curiosity. I'd be happy to get clarifications on these points, but these are not blocking issues at all. - The definition of similarity (in Section 2) looks loose to me: Similar Location: A suggested civic location that is similar to an Invalid Location which was used in a LoST query, but which has one or more elements added, modified, or removed such that the suggested location is a Valid Location. If we apply this definition literally, a completely "different" location could be considered to be "similar" as long as it's valid, since all editorial operations can be applied for arbitrary times, right? Perhaps it's intentionally kept loose and left to the server implementation and discretion, but it would be also nice if it gives some example of what would NOT be considered to be similar (for example, what if an element contains a misspelling and fixing it would make it valid?). - Also related to the above definition, can "Similar Location" be used only when the input is invalid? For example, what if both "6000 15th Avenue Northwest" and "6000 15th Avenue Southwest" exist and the input is either of them in a complete form, can we include the other as a "Similar Location"?