[PROJ] Questions about ESRI WKT -> proj operation mappings

[Nyall Dawson]

Hi list,

While attempting to fill some of the gaps in the ESRI WKT to proj
operation mapping file
(https://github.com/OSGeo/PROJ/blob/master/scripts/build_esri_projection_mapping.py)
I've hit some questions:

- ESRI Hammer_Aitoff projection: is this the same as proj's "hammer",
but with the fixed W=0. parameter mentioned in
https://proj.org/operations/projections/hammer.html?

- Flat_Polar_Quartic: is this the same as the McBryde-Thomas
Flat-Polar Quartic exposed by proj?

- "Cube": I'm guessing this is
https://pro.arcgis.com/en/pro-app/help/mapping/properties/cube.htm,
and differs from https://proj.org/operations/projections/qsc.html
because qsc only supports a single face at a time..?

Anyone able to assist here?

Nyall