[cxS]

as they do not contain information on how objects should interact

Explain.. I doubt any language does, and this would be an even thinner line for OO languages, of which, C# is. Define "objects" in this context, because that can have many meanings for .NET.

and even explicitly states that a conforming version of C# only follows some of the declared norms, and is allowed to add methods, namespaces, classes, etc.

What exactly explicitly states this? (reference)....Although, you're saying languages like C++ are not this way, you mean? :S