Sure, disambiguation is important, but do we need to do that at the serialization level? We increase the parsing and transformation costs in DNS, when it seems

Sure, disambiguation is important, but do we need to do that at the serialization level? We increase the parsing and transformation costs in DNS, when it seems like what we really need is clear rules about what unicode values are legal and which are not. The example of umlaut is really good one though, as the umlaut can be an extra code point, or part of the actual character. I can see why we'd want to be explicit that both are not allowed in DNS... It still feels like we're solving this issue at the wrong layer, i.e. the protocol layer, as opposed to the application layer. I'm 100% in agreement on needing solutions here, but I think your example illustrates that it's a higher-order issue for applications, and not the protocol.