I have reviewed draft-ietf-core-oscore-edhoc-09 and while I have a general understanding about CoAP, I am not familiar with EDHOC or the details of OSCORE. Perhaps some of my questions have simple obvious answers for those familiar with the technologies. - The document title consists of six token, three of them are acronyms. This is crisp and short but unless you know the acronyms, it is hard to tell what this document is about. Sure, expanding all acronyms in the title makes it long but it might make the abstract, which uses the acronyms as well, more accessible as well... Using Ephemeral Diffie-Hellman Over COSE (EDHOC) with the Constrained Application Protocol (CoAP) and Object Security for Constrained RESTful Environments (OSCORE) - It is difficult to judge whether there are any possible side effects of the proposed optimization, which essentially piggybacks the first OSCORE exchange on the last EDHOC exchange. Optimizations of this kind sometimes cause subtle side-effects. A security review should be done to ensure that there is no impact on the security of EDHOC and OSCORE. I am not able to judge this in a time efficient manner. - It is not clear to me how this works in mixed deployments where some responders implement this specification but others do not. How does the initiator figure out whether sending a combined message makes sense? It seems question is handled by the application profile. But then section 5. starts with "can include the information below" followed by some SHOULD text. So what does this combination of "can include ... SHOULD ..." mean? - What does it mean for the client to 'bear [something] in mind'? Should the text not spell out clearly what the client is expected to do in this case (SHOULDS not send a combined EDHOC + OSCORE request)? - Is section 4 telling me that the OSCORE ID and EDHOC ID can be the same (but they do not have to be the same) while with the proposed optimization they must be the same? Or is there always an identity mapping between the OSCORE ID and EDHOC ID? If so, why is section 4 even necessary? I have ticked 'has issues' because there is no reviewer 'has questions' option. It is most likely that my questions have very simple answers - so take a look at my questions and it is absolutely fine to move ahead if my questions have obvious answers or are just a lack of understanding of the context.