The European Terrestrial Reference System 1989 (ETRS89), introduced in Europe as a geodetic reference system, is implemented in Romania (by the ODG of the ANCPI No. 212/2009) for the creation of a modern National Spatial Geodetic Network (RGNS) and the realization of pan-European cartographic products.
ETRS89 is defined according to the international standard ISO 19111, as composed of the ETRS89 geodetic datum, based on the GRS80 (Geodetic Reference System 1980) ellipsoid and the elliptical geodetic coordinate system.
• In Romania, two reference systems are officially used:
• The 1942 coordinate system (internationally known as "S-42"), based on the 1940 Krasovski ellipsoid, with the fundamental point at Pulkovo (Russia), together with the 1970 Stereographic projection;
• Reference system based on the reference 1910 Hayford ellipsoid, oriented on the fundamental astronomical point located inside the Military astronomical observatory in Bucharest, together with the 1930 stereographic projection – Bucharest secant plane.
The coordinates transformations used in Romania can be classified into two categories:
• Local coordinate transformations without a model of Helmert data distortion with 7 parameters or 4 parameters (standard deviation is around ± 0.10 m or less, depending on the distance between the joint points);
• Coordinate transformations with a data distortion model for which the standard deviation of the transformed coordinates is around ± 0.10-0.15 m, provided the existence of a sufficient number of joint points spread evenly across the entire country territory.