[PROJ] EPSG:5490 - How do I know if it is included in PROJ?

[Even Rouault]

Hélène,

> 
> Apologies if this is extra-basic : as a newbie, I was looking for a list of
> projections covered by PROJ, and can't find any so far.

In a general way, this might depend on the PROJ version you are considering.

For PROJ 5.2 or older, you have to look at the epsg file:
https://github.com/OSGeo/PROJ/blob/5.2/nad/epsg

For PROJ 6 or newer, in one of those files depending on the nature of the CRS:
https://github.com/OSGeo/PROJ/blob/master/data/sql/geodetic_crs.sql
https://github.com/OSGeo/PROJ/blob/master/data/sql/projected_crs.sql

Or use the projinfo utility:

projinfo EPSG:5490
PROJ.4 string:
+proj=utm +zone=20 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs 
+type=crs

WKT2_2018 string:
PROJCRS["RGAF09 / UTM zone 20N",
    BASEGEOGCRS["RGAF09",
        DATUM["Reseau Geodesique des Antilles Francaises 2009",
            ELLIPSOID["GRS 1980",6378137,298.257222101,
                LENGTHUNIT["metre",1]]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["degree",0.0174532925199433]],
        ID["EPSG",5489]],
    CONVERSION["UTM zone 20N",
        METHOD["Transverse Mercator",
            ID["EPSG",9807]],
        PARAMETER["Latitude of natural origin",0,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8801]],
        PARAMETER["Longitude of natural origin",-63,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8802]],
        PARAMETER["Scale factor at natural origin",0.9996,
            SCALEUNIT["unity",1],
            ID["EPSG",8805]],
        PARAMETER["False easting",500000,
            LENGTHUNIT["metre",1],
            ID["EPSG",8806]],
        PARAMETER["False northing",0,
            LENGTHUNIT["metre",1],
            ID["EPSG",8807]]],
    CS[Cartesian,2],
        AXIS["(E)",east,
            ORDER[1],
            LENGTHUNIT["metre",1]],
        AXIS["(N)",north,
            ORDER[2],
            LENGTHUNIT["metre",1]],
    USAGE[
        SCOPE["unknown"],
        AREA["Caribbean - French Antilles west of 60°W"],
        BBOX[14.08,-63.66,18.32,-60]],
    ID["EPSG",5490]]

> More specifically, I was wondering whether the horizontal system EPSG:5490
> (RGAF09) is covered by PROJ -

The answer is yes for all recent enough PROJ versions.

Even

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