coordinate system

Also referred to as a coordinate reference system (see ISO 19111:2019).

(1) An exact definition of a system of mathematics and geodetic constants that defines how a specific geographic location is converted to a set of two or three numbers, such as an x- and y-value. In the cartographic context, most coordinate systems are Cartesian.

(2) A set of transformations that allow GNSS positions to be transformed to projection coordinates with elevations above the geoid. Essentially, a coordinate system consists of a datum transformation, a geoid model, and a coordinate projection definition.

• The datum transformation is one of those defined in the database and effectively includes the definition of the datum the coordinate projection is based on.
• Typically an existing geoid model is assigned to the coordinate system, but it is also possible to specify a constant geoid separation instead of a geoid model or to specify that no geoid model should be used.
• A large number of coordinate projection types (for example, Transverse Mercator, and Lambert One Parallel) are available for allocation to a coordinate system.