{
  "title": "Feature",
  "description": "A GeoJSON Feature",
  "allOf": [
    { "$ref": "http://json.schemastore.org/geojson.json#/definitions/feature" }
  ],
  "type": "object",
  "required": ["id"],
  "properties": {
    "id": {
      "type": "string",
      "pattern": "^[-_.A-Za-z0-9]+$"
    }
  }
}