[PROJ] WGS84 to GDA94 and GDA2020

[Nigel Stewart]

Hello all, first time posting to this list.

We've come across something a bit disconcerting using PROJ. To and from
GDA94 and GDA2020 (Australia) PROJ is using Helmert step, but from a
WGS84-based transverse mercator the Helmert is not used and the coordinates
are exactly the same for both EPSG:28356 (GDA94) and EPSG:7856 (GDA2020).
ChatGPT has something to say about telling PROJ about EPSG:8048 for the
Helmert transformation. Are we being unrealistic about just expecting it to
work without forming our own pipeline for this particular case? Or does
this seem like some sort of corner case that PROJ could implement in
future? Any perspective or guidance appreciated.

The ChatGPT opinion is along the lines of:
cs2cs +init=epsg:4326 +to +init=epsg:28356 +step +init=epsg:8048

Thanks,

Nigel Stewart
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