Topographic mapping.
In some references incorrectly named "Gandajika 1970". See datum code 6685.
Definition: JSON
{ "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json", "type": "GeodeticReferenceFrame", "name": "Gan 1970", "ellipsoid": { "name": "International 1924", "semi_major_axis": 6378388, "inverse_flattening": 297 }, "scope": "Topographic mapping.", "area": "Maldives - onshore.", "bbox": { "south_latitude": -0.69, "west_longitude": 72.81, "north_latitude": 7.08, "east_longitude": 73.69 }, "id": { "authority": "EPSG", "code": 6684 } }