12.15.6 Geometry Property Functions

12.15.6.1 General Geometry Property Functions
12.15.6.2 Point Property Functions
12.15.6.3 LineString Property Functions
12.15.6.4 MultiLineString Property Functions
12.15.6.5 Polygon Property Functions
12.15.6.6 MultiPolygon Property Functions
12.15.6.7 GeometryCollection Property Functions

Each function that belongs to this group takes a geometry value as its argument and returns some quantitative or qualitative property of the geometry. Some functions restrict their argument type. Such functions return NULL if the argument is of an incorrect geometry type. For example, the Area() polygon function returns NULL if the object type is neither Polygon nor MultiPolygon.