Control points and their coordinates and elevations define in practice the reference system for coordinates and elevations used in Finland. The NLS benchmark register contains information about nationwide control points and benchmarks. The marks are mainly horizontal and elevation control points in classes 1–3 measured by the National Land Survey of Finland. The product belongs to the open data of the National Land Survey of Finland. More information: Topographic data and how to acquire it http://www.maanmittauslaitos.fi/en/maps-and-spatial-data/expert-users/topographic-data-and-how-acquire-it.