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M (geography Data Type)

The M (measure) value of the geography instance. The semantics of the measure value are user-defined but generally describe the distance along a linestring. For example, the measure value could be used to keep track of mileposts along a road.



Return Types

SQL Server type: float

CLR type: SqlDouble


The value of this property is null if the geography instance is not a Point, as well as for any Point instance for which it is not set.

This property is read-only.

M values are not used in any calculations made by the library and will not be carried through any library calculations.


The following example creates a Point instance with Z (elevation) and M (measure) values and uses M to fetch the M value of the instance.

DECLARE @g geography;
SET @g = geography::STGeomFromText('POINT(-122.34900 47.65100 10.3 12)', 4326);