EPSG:6279

DATUM["OS_SN_1980",
    SPHEROID["Airy 1830",6377563.396,299.3249646,
        AUTHORITY["EPSG","7001"]],
    AUTHORITY["EPSG","6279"]]

DATUM["OS (SN) 1980",
    ELLIPSOID["Airy 1830",6377563.396,299.3249646,
        LENGTHUNIT["metre",1]],
    ID["EPSG",6279]]

DATUM["D_OS_SN_1980",
    SPHEROID["Airy_1830",6377563.396,299.3249646]]

{
    "$schema": "https://proj.org/schemas/v0.5/projjson.schema.json",
    "type": "GeodeticReferenceFrame",
    "name": "OS (SN) 1980",
    "ellipsoid": {
        "name": "Airy 1830",
        "semi_major_axis": 6377563.396,
        "inverse_flattening": 299.3249646
    },
    "scope": "Geodesy.",
    "area": "Ireland - onshore. United Kingdom (UK) - onshore - England; Scotland; Wales; Northern Ireland. Isle of Man.",
    "bbox": {
        "south_latitude": 49.81,
        "west_longitude": -10.56,
        "north_latitude": 60.9,
        "east_longitude": 1.84
    },
    "id": {
        "authority": "EPSG",
        "code": 6279
    }
}