I would point out that these enum names don't follow the Phobos naming conventions. They should be PascalCased - e.g. `StdASCIIEC` - though that is a bit ugly (and the values should be camelCased). Or maybe `StdASCIITestChars`? I don't know. Maybe it's okay, because they're private and not part of the public API, but I still don't like the idea of breaking the naming conventions.