The IEC 60870-5-103 standard defines remote control of indications or control of objects without corresponding indication. Example of a controllable indication could be circuit breaker ON/OFF whose position can be monitored as a normal ASDU 1 indication, and which also can be controlled ON or OFF by the IEC 60870-5-103 client. Example of a control object without corresponding indication could be an acknowledge object, for example LED Reset.
According to the standard the remote control operations are performed using the ASDU 20 object type. Controllable indications usually can be controlled into two positions, ON or OFF. Acknowledge points can only be controlled ON. If the IED is in local mode, the remote CB controls are rejected.