184.108.40.206 Membership-Of Pattern
These methods enable a client to obtain the group membership of a user or the alias membership of a set of SIDs. In mixed mode domains, these methods are useful in approximating the authorization data associated with an authentication request for a given user. However, in native mode domains, these methods are not accurate because the authorization building process is more complex than what these methods enable. This means that in native mode domains, these methods MUST NOT be used to approximate the authorization data for a given user accessing a resource.
A client MUST first obtain a handle to the user or domain, depending on the method.
See section 1.3 for a description of the "membership-of" pattern of methods.