In theory the purpose of having the IETF meet as it does is to encourage people in different areas to work together. So why is it that whenever I propose designing something for WG A in a fashion that allows it to be used by working group B along the road that there is a constant chorus of 'out of scope'? If we are going to work together then it has to be possible for someone in the S/MIME world to say in their WG 'hey, OpenPGP has already done it this way, why not copy'. Equally it should be possible for someone in IPSEC to say 'hey, the TLS folk have won, why not work on a common approach to key exchange'. Instead anyone suggesting that we try to do things in a consistent way across IETF have to keep explaining why an approach that allows for consistency across WGs should be considered. I think people need to think very carefully before entering into discussions if the only input they have is to shoot down a use case. If there are two proposals on the table and no clear way to choose between them, the way to address the issue is to look for more use cases that can serve as a tie breaker. The point of working group focus is to get work done. Litigating the question of whether a use case has standing is invariably a waste of time. None of us can fully anticipate the uses for which a technology will be put and the most successful IETF protocols are precisely the ones that have supported such uses. Just because a use case is on the table does not mean that there is an obligation to address it. The point of a charter is to focus a working group on a set of deliverables. A charter should never become an obstacle to working across working groups or across areas. In the particular case that has set me off this time, the issue is whether a not-yet WG would spin up yet another IANA registry for its own exclusive use or make use of the MIME Content-Type registry. Of course if you narrow the scope of the problem to one WG and nothing outside its scope, there is 'nothing to choose' between the two approaches. A new registry will serve just as well as the existing one (besides creating more work) because the advantages of using Content-Type have been ruled out of scope. But it doesn't bring any advantage either. One of the things we seem to lack in IETF is some sort of friction when it comes to creating new registries. JOSE has just created a new set of crypto registries instead of re-using the PEM set and there are a half dozen other crypto registries besides. We seem to re-invent the MIME content-type registry repeatedly. And quite why .well-known, URI and SRV should be separate is a mystery to me. In general, the way to get interoperation between protocols and avoid silos is for people to use existing registries whenever possible.