[PROJ] Unexpected no NADCON5 transformations

[Javier Jimenez Shaw]

Hi devs,

I was going to get an order of magnitude of NADCON5 transformations added
in PROJ 9.2.0 (+ PROJ-data), and I found that they are not always applied.
As they are datum transformations, I would assume that they are independent
of the vertical system, but maybe I am wrong.

Going from WGS84(3D) to NAD83(2011) + NAVD88 height produces different
horizontal values than the input (what I expected)

$ echo 40 -100 0 | PROJ_NETWORK=ON ./cs2cs EPSG:4979 EPSG:6318+5703 -d 8
39.99999330 -99.99999115 25.47826194

However any other combination using 2D+vert or 3D is not changing the
horizontal coordinates.

$ echo 40 -100 0 | PROJ_NETWORK=ON ./cs2cs EPSG:4326+5773 EPSG:6319 -d 8
40.00000000 -100.00000000 -25.05249596
$ echo 40 -100 0 | PROJ_NETWORK=ON ./cs2cs EPSG:4979 EPSG:6319 -d 8
40.00000000 -100.00000000 0.00000000
$ echo 40 -100 0 | PROJ_NETWORK=ON ./cs2cs EPSG:4326+5773 EPSG:6318+5703 -d
8
40.00000000 -100.00000000 -0.49709511

Enabling the debug messages, the first case is clearly looking for the
nadcon5 grids. The other 3 are not.

Is that expected?

Thanks.

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