westausatc - I recently suggested just that to a manager who in the distant past held a rating on the airspace in question. I received a confused look and "why would you want that?"
When TAAATS was first commissioned, there was a reference in MATS that clearly stated that the RADAR separation standard on a TAAATS display within 100NM was 3NM. The only limitation being the range-scale on the display during the application of the separation standard. Melbourne Centre Local Instructions stated otherwise and denied us the application of what would have been a distinctly advantageous improvement in our ability to provide a service within 100NM of Perth with the introduction of TAAATS.
The reference in MATS was quickly removed in a subsequent amendment... and quickly forgotten.
At that time we asked the Melbourne techs whether it was true that the Eurocat processing was accurate enough to allow us to apply a 3NM separation standard on a TAAATS display within 100NM and they said "yes".
I then asked JH why the reference in MATS had been removed and he said:
"Because we don't trust En-route controllers to apply a 3NM separation standard".
Unless something has changed, it would seem that there is no technical reason why a 3NM separation standard could not be applied within 100NM on the appropriate range-scale. Which leaves only one problem... someone has to sign-off on it... which means... take responsibility for it.
Which is why we won't be taking a seat in Le Grenier à Pain, Montmarte for some time.