ST_M — Return the M coordinate of the point, or NULL if not available. Input must be a point.
float ST_M(geometry  a_point);
Return the M coordinate of the point, or NULL if not available. Input must be a point.
| ![[Note]](images/note.png) | |
| This is not (yet) part of the OGC spec, but is listed here to complete the point coordinate extractor function list. | 
 This method implements the OpenGIS Simple Features
 Implementation Specification for SQL 1.1.
 This method implements the OpenGIS Simple Features
 Implementation Specification for SQL 1.1.
 This method implements the SQL/MM specification.
 This method implements the SQL/MM specification.
 This function supports 3d and will not drop the z-index.
 This function supports 3d and will not drop the z-index.