{
  "name": "z",
  "type": "function",
  "groups": ["GeometryGroup"],
  "description": "Returns the z coordinate of a point geometry, or NULL if the geometry has no z value.",
  "arguments": [{
    "arg": "geometry",
    "description": "a point geometry"
  }],
  "examples": [{
    "expression": "z( geom_from_wkt( 'POINTZ(2 5 7)' ) )",
    "returns": "7"
  }],
  "tags": ["point", "coordinate"]
}