They are ICAO standards. As hopefully my final comment on this thread, ICAO requires ATC to apply separation which many countries do as a minimum whereas Australia and other countries also apply separation assurance.
For instance, with applying separation between aircraft, a controller may not act until an event occurs and then turn, descend or climb an aircraft to maintain separation. With separation assurance the controller will manage traffic so if there is something unexpected, the aircraft will remain separated if the controller can't intervene. Nothing like a student doing a go around with an open microphone and ATC can only sit and watch.