> >> The `is` prefix doesn’t provide any functionality that would otherwise >> be unavailable. It doesn’t add any value, yet causes incompatibility, >> author confusion, and it increases implementation complexity. > > I don't see any evidence that it adds no value. Support for existing > implementations is value.
It adds no value because it doesn’t enable any new functionality. I agree support for existing implementations would have some value, but given that existing implementations disagree on the properties for which they support `is` that is not going to happen anyway. It’s impossible to be compatible with all those different implementations at the same time.
