EPSG:9540

COMPD_CS["RGNC91-93 + NGNC08 height",
    GEOGCS["RGNC91-93",
        DATUM["Reseau_Geodesique_de_Nouvelle_Caledonie_91-93",
            SPHEROID["GRS 1980",6378137,298.257222101,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","6749"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4749"]],
    VERT_CS["NGNC08 height",
        VERT_DATUM["Nivellement General de Nouvelle Caledonie 2008",2005,
            AUTHORITY["EPSG","1255"]],
        UNIT["metre",1,
            AUTHORITY["EPSG","9001"]],
        AXIS["Gravity-related height",UP],
        AUTHORITY["EPSG","9351"]],
    AUTHORITY["EPSG","9540"]]

COMPOUNDCRS["RGNC91-93 + NGNC08 height",
    GEOGCRS["RGNC91-93",
        DATUM["Reseau Geodesique de Nouvelle Caledonie 91-93",
            ELLIPSOID["GRS 1980",6378137,298.257222101,
                LENGTHUNIT["metre",1]]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["degree",0.0174532925199433]],
        CS[ellipsoidal,2],
            AXIS["geodetic latitude (Lat)",north,
                ORDER[1],
                ANGLEUNIT["degree",0.0174532925199433]],
            AXIS["geodetic longitude (Lon)",east,
                ORDER[2],
                ANGLEUNIT["degree",0.0174532925199433]]],
    VERTCRS["NGNC08 height",
        VDATUM["Nivellement General de Nouvelle Caledonie 2008"],
        CS[vertical,1],
            AXIS["gravity-related height (H)",up,
                LENGTHUNIT["metre",1]]],
    USAGE[
        SCOPE["Spatial referencing."],
        AREA["New Caledonia - Belep, Grande Terre, Ile des Pins, Loyalty Islands (Lifou, Mare, Ouvea)."],
        BBOX[-22.73,163.54,-19.5,168.19]],
    ID["EPSG",9540]]

GEOGCS["GCS_RGNC_1991-93",
    DATUM["D_Reseau_Geodesique_de_Nouvelle_Caledonie_1991-93",
        SPHEROID["GRS_1980",6378137.0,298.257222101]],
    PRIMEM["Greenwich",0.0],
    UNIT["Degree",0.0174532925199433]],
VERTCS["NGNC08_height",
    VDATUM["Nivellement_General_de_Nouvelle_Caledonie_2008"],
    PARAMETER["Vertical_Shift",0.0],
    PARAMETER["Direction",1.0],
    UNIT["Meter",1.0]]

proj4.defs("EPSG:9540","+proj=longlat +ellps=GRS80 +vunits=m +no_defs +type=crs");

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "CompoundCRS",
    "name": "RGNC91-93 + NGNC08 height",
    "components": [
        {
            "type": "GeographicCRS",
            "name": "RGNC91-93",
            "datum": {
                "type": "GeodeticReferenceFrame",
                "name": "Reseau Geodesique de Nouvelle Caledonie 91-93",
                "ellipsoid": {
                    "name": "GRS 1980",
                    "semi_major_axis": 6378137,
                    "inverse_flattening": 298.257222101
                }
            },
            "coordinate_system": {
                "subtype": "ellipsoidal",
                "axis": [
                    {
                        "name": "Geodetic latitude",
                        "abbreviation": "Lat",
                        "direction": "north",
                        "unit": "degree"
                    },
                    {
                        "name": "Geodetic longitude",
                        "abbreviation": "Lon",
                        "direction": "east",
                        "unit": "degree"
                    }
                ]
            },
            "remarks": "Replaces older systems IGN56 Lifou, IGN72 Grande Terre, ST87 Ouvea, IGN53 Mare, ST84 Ile des Pins, ST71 Belep and NEA74 Noumea. Replaced by RGNC15 (CRS 10310). See CRS code 10307 for alternate system with axes reversed used by DITTT for GIS purposes."
        },
        {
            "type": "VerticalCRS",
            "name": "NGNC08 height",
            "datum": {
                "type": "VerticalReferenceFrame",
                "name": "Nivellement General de Nouvelle Caledonie 2008"
            },
            "coordinate_system": {
                "subtype": "vertical",
                "axis": [
                    {
                        "name": "Gravity-related height",
                        "abbreviation": "H",
                        "direction": "up",
                        "unit": "metre"
                    }
                ]
            }
        }
    ],
    "scope": "Spatial referencing.",
    "area": "New Caledonia - Belep, Grande Terre, Ile des Pins, Loyalty Islands (Lifou, Mare, Ouvea).",
    "bbox": {
        "south_latitude": -22.73,
        "west_longitude": 163.54,
        "north_latitude": -19.5,
        "east_longitude": 168.19
    },
    "id": {
        "authority": "EPSG",
        "code": 9540
    }
}

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=longlat +ellps=GRS80 +vunits=m +no_defs +type=crs">
	<Layer srs="+proj=longlat +ellps=GRS80 +vunits=m +no_defs +type=crs">
	</Layer>
</Map>

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 9540, 'EPSG', 9540, '+proj=longlat +ellps=GRS80 +vunits=m +no_defs +type=crs', 'COMPD_CS["RGNC91-93 + NGNC08 height",GEOGCS["RGNC91-93",DATUM["Reseau_Geodesique_de_Nouvelle_Caledonie_91-93",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","6749"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4749"]],VERT_CS["NGNC08 height",VERT_DATUM["Nivellement General de Nouvelle Caledonie 2008",2005,AUTHORITY["EPSG","1255"]],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Gravity-related height",UP],AUTHORITY["EPSG","9351"]],AUTHORITY["EPSG","9540"]]');