Originally Posted by
Icarus2001
How is that functionally different to a clearance to operate in the TRA?
Because a clearance is only provided in airspace where there is a specified level air traffic control service provided, which in this case is clearly absent. So the only other way to enter and operate in a TRA is to obtain approval to do so from the 'controlling authority'. The OAR (Office of Airspace Regulation) in CASA will nominate who, or which organisation is that authority when they issue the Instrument that creates the TRA.