# What geospatial leaves out, and what to use instead

Some geospatial work is left out of the language. Each row says why, and
what to use instead:

| Left out | Why | Instead |
|---|---|---|
| `geo.buffer` | PostGIS buffers a `geography` by projecting it to a planar system it picks, so the result depends on PROJ's choice and can't be reproduced in Jadpo's code | `within(distance:)` and `Circle` for "near"; a provider package for drawn buffers |
| Coordinate systems other than WGS84 (British National Grid and the rest) | Accurate conversion needs datum grids (OSTN15 for Great Britain), megabytes of data per system that every wasm32 build would carry | `EastingNorthing` kept with its `Crs`; a provider package later |
| Straight edges on longitude and latitude (`geometry` columns) | Two edge meanings would split every operation in two; the standard library stores geometries as `geography` | Great circles ([Edges are great circles](what-every-geospatial-operation-follows.md#edges-are-great-circles)) |
| Routing, travel times, geocoding | Network data and paid services | Provider packages ([Integrations](external-services.md)) |
| Nearest first without a radius, farthest first, pages by distance | Disagree with `geo.distance` or can't use the index | A radius ([Nearest first inside a radius](geospatial-queries.md#nearest-first-inside-a-radius)) |
| Simplifying, unions, splitting at the antimeridian | None of the standard library's [scenario applications](scenario-applications.md) needs them; each is a large algorithm | Later, when one does |
| `GeometryCollection`, and a `Feature` with no geometry | Rare, and each makes every consumer handle an extra case | A `MultiPolygon`, or the right geometry type |
| Altitude in any operation | WGS84's operations are on the surface; height above the ellipsoid isn't height above the ground | Kept and stored, never measured |