But isn't it a magic string already, because of the {parameter} parsing? I don't really see an issue in treating it as if it was just `Request-URI` (in RFC2616

But isn't it a magic string already, because of the {parameter} parsing? I don't really see an issue in treating it as if it was just `Request-URI` (in RFC2616 terms) with some parameter magic, and became a Request-Line-resembling `[ Method SP ] Request-URI`, which is fully backwards-compatible and isn't exactly surprising to anyone. I think it's pretty much obvious what it does even if one never sees the documentation. And given that `Method` is either one of a few predefined constants or `extension-method = token`, and `token` excludes whitespace, slashes and all sort of brackets I don't think there's a chance of confusion or misparsing there, even for weirdest custom methods.