I'm not really worried about how it looks on the receiving end, just that it shows up in some form. My suggestion for ?starlight was only if you weren't going be continuum compliant. If you are, then there's no issue. And your arguments against something like ?starlight are flawed: 1) If the server DOES need to distinguish clients, it has to query all of them. That means packets to all clients, even though only a very small percentage are starlights. I personally don't think the overhead of a single packet is significant, but you brought it up. 2&3) Making mapping impossible is worse than making it mandatory. If bugs are discovered in previous versions, then with your capability system it'll be impossible to resolve (without adding a capability for no_bug_x, which I'm sure you'll agree isn't clean). 4) Continuum compliance is really not something you should be changing at runtime. 5) Can send it out of band, either using invalid message settings or by creating a packet for it. Or not worry that continuum users can disable their continuum compliance.