With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: As of July 2009, Microsoft added and CLI to the list of specifications that the Microsoft Community Promise applies to, so anyone can safely implement specified editions of the standards without fearing a patent lawsuit from Microsoft. To implement the CLI standard requires conformance to one of the supported and defined profiles of the standard, the minimum of which is the kernel profile. The kernel profile is actually a very small set of types to support in comparison to the well known core library of default.NET installations. However, the conformance clause of the CLI allows for extending the supported profile by adding new methods and types to classes, as well as deriving from new namespaces. But it makes impossible adding new members to interfaces. This means that the features of the CLI can be used and extended, as long as the conforming profile implementation does not change the behavior of a program intended to run on that profile, while allowing for unspecified behavior from programs written specifically for that implementation.
text_B: Are Microsoft interfaces open to new members?
NO.