Geometry coordinates

Each point comprising a non-empty geometry includes exactly one set of X and Y position coordinates. Optionally, each location can include one Z position coordinate and one M measurement coordinate.

All coordinate values are represented as double-precision numbers.

An X position coordinate specifies the distance to the east (if positive) or west (if negative) of a location relative to a point of reference.
A Y position coordinate specifies the distance to the north (if positive) or south (if negative) of a location relative to a point of reference.
A Z position coordinate specifies an altitude (if positive) or depth (if negative), normal to the earth's surface, of the location determined by the X and Y coordinates.
An M measurement coordinate specifies numerical information about the location determined by the X and Y coordinates, such as temperature, rainfall, or distance from a specific location.