ISO 22670:2006 specifies a return-channel-frames (RCF) service for a space link extension (SLE). The RCF service is an SLE transfer service that delivers to a mission user all telemetry frames from one master channel or one virtual channel.
It defines, in an abstract manner, the RCF service in terms of
- the operations necessary to provide the service;
- the parameter data associated with each operation;
- the behaviours that result from the invocation of each operation;
- the relationship between, and the valid sequence of, the operations and resulting behaviours.