The PrincipalPermission class allows security checks against the active principal. This is done by using the language constructs that are defined for both imperative and declarative security actions. To perform an imperative security demand for membership in a built-in Microsoft Windows group, you must first set the default principal policy to the Windows principal by calling the SetPrincipalPolicy (PrincipalPolicy.WindowsPrincipal) statement. Construct a PrincipalPermission object specifying the group name. To specify the group name, you can provide just the group name, or you can preface the group name with either "BUILTIN\" or the computer name and a backslash. Finally, call the PrincipalPermission.Demand method. There is another method of identifying group membership, i.e. by using the PrincipalPermission class or the PrincipalPermissionAttribute attribute derived from the System.Security.Permissions namespace. The PrincipalPermission object identifies that the identity of the active principal should match its information with the identity information that is passed to its constructor. The identity information contains the user's identity name and role.