EPSG:6807

DATUM["Nouvelle_Triangulation_Francaise_Paris",
    SPHEROID["Clarke 1880 (IGN)",6378249.2,293.466021293627,
        AUTHORITY["EPSG","7011"]],
    AUTHORITY["EPSG","6807"]],
PRIMEM["Paris",2.33722917,
    AUTHORITY["EPSG","8903"]]

DATUM["Nouvelle Triangulation Francaise (Paris)",
    ELLIPSOID["Clarke 1880 (IGN)",6378249.2,293.466021293627,
        LENGTHUNIT["metre",1]],
    ID["EPSG",6807]],
PRIMEM["Paris",2.5969213,
    ANGLEUNIT["grad",0.0157079632679489],
    ID["EPSG",8903]]

DATUM["D_NTF",
    SPHEROID["Clarke_1880_IGN",6378249.2,293.466021293627]],
PRIMEM["Paris",2.33722917]

{
    "$schema": "https://proj.org/schemas/v0.5/projjson.schema.json",
    "type": "GeodeticReferenceFrame",
    "name": "Nouvelle Triangulation Francaise (Paris)",
    "ellipsoid": {
        "name": "Clarke 1880 (IGN)",
        "semi_major_axis": 6378249.2,
        "semi_minor_axis": 6356515
    },
    "prime_meridian": {
        "name": "Paris",
        "longitude": {
            "value": 2.5969213,
            "unit": {
                "type": "AngularUnit",
                "name": "grad",
                "conversion_factor": 0.0157079632679489
            }
        }
    },
    "scope": "Topographic mapping.",
    "area": "France - onshore - mainland and Corsica.",
    "bbox": {
        "south_latitude": 41.31,
        "west_longitude": -4.87,
        "north_latitude": 51.14,
        "east_longitude": 9.63
    },
    "id": {
        "authority": "EPSG",
        "code": 6807
    }
}