# Geographic areas

Each metro defines its own `areaTypes` (e.g. neighbourhood, ward). Each GeoJSON feature has a globally unique stable `id`, a `metroId`, a `typeId` and a Unicode `name`. IDs are not derived from names. A name or boundary may change without changing the ID when the underlying area retains its identity.

The API returns a full current dataset as a JSON envelope containing a GeoJSON `FeatureCollection`. Geometry is mobile-optimized WGS84 (`[longitude, latitude]`) `Polygon` or `MultiPolygon`, including holes. It is not required to be disjoint or non-overlapping. The client may match several areas for one position and must define its own boundary-point tolerance and presentation policy.

GeoJSON ring closure, winding order, valid topology, type references, unique IDs and boundary simplification quality require geospatial validation beyond ordinary JSON Schema. These checks belong to the future publishing workflow; clients should still reject malformed datasets.

The included Mississauga polygons are **synthetic illustrative rectangles, not official or accurate municipal boundaries**. Do not ship them as production geofences. Replace with licensed, verified, simplified real boundaries before implementation or release.

No historical area geometries are provided in v1. All text is Unicode/UTF-8, without translation or localization requirements.