ISO 22664:2016 defines the TC Space Data Link Protocol in terms of: a) the services provided to the users of this protocol; b) the protocol data units employed by the protocol; and c) the procedures performed by the protocol. It does not specify: a) individual implementations or products; b) the implementation of service interfaces within real systems; c) the methods or technologies required to perform the procedures; or d) the management activities required to configure and control the protocol.