NOT_UNDERSTOOD

The access control rule is too complex to be represented in the current Telepathy API.

The associated variant is meaningless. Setting this mode is never valid; the connection manager MUST raise an error if this is attempted. XEP-0016 Privacy Lists can easily produce access control mechanisms that can't be expressed in a simpler API. We need to be able to at least indicate that fact. The associated variant in Access_Control is ignored.