# CRS Policy

## API Boundary
GeoJSON in API responses should be EPSG:4326.

## Analytical Operations
For Belgium/Kempen projected calculations, use EPSG:31370 where possible.

## Raster Operations
Raster operations must preserve source CRS unless a reproject operation is explicitly requested.

## Required Metadata
Every dataset must store:
- source CRS;
- normalized CRS string;
- bounds in source CRS;
- bounds in EPSG:4326;
- transform/affine for rasters where available.

## Unsupported Cases
If CRS cannot be determined:
- dataset can be stored as `metadata_failed` or `requires_crs`;
- processing requiring geospatial alignment must be blocked;
- UI must ask for CRS or show limitation.