Geodesy.
The Chua origin and associated network is in Brazil with a connecting traverse through northern Paraguay. It was used in Brazil only as input into the Corrego Allegre adjustment and for government work in Distrito Federal.
Brazil - south of 18°S and west of 54°W, plus Distrito Federal. Paraguay - north.
Definition: JSON
{ "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json", "type": "GeodeticReferenceFrame", "name": "Chua", "ellipsoid": { "name": "International 1924", "semi_major_axis": 6378388, "inverse_flattening": 297 }, "scope": "Geodesy.", "area": "Brazil - south of 18°S and west of 54°W, plus Distrito Federal. Paraguay - north.", "bbox": { "south_latitude": -31.91, "west_longitude": -62.57, "north_latitude": -15.37, "east_longitude": -47.1 }, "id": { "authority": "EPSG", "code": 6224 } }