In the Dynamic Link Library GeoDLL geodesic functions like coordinate transformation, datum changes, meridian strip changes, user defined coordinate and reference systems, distance calculation, maps functions, Digital Elevation Models and more geodesic functions are contained to bind them into own applications. WINDOWS operating system allows building of function libraries intended for use by applications, the so-called Dynamic Link Libraries. The application uses functions stored in the DLL by making a DLL call. The language used for developing applications that call functions of the DLL is not important. It could be C++, Delphi, MS-Access, Visual Basic or CA-Visual Objects or other. Therefore the DLL is delivered with interface source codes to many programming languages. With GeoDLL world wide Coordinate Transformations and Reference System Transformations (datum shifts) are available: 1. The current and many historical Coordinate and Reference Systems of all States of the European Union (EU) including the eastern extension from April 2004 and other European Systems. 2. The US- and Canadian State Plane- and other Coordinate and Reference Systems of the North American Continent. 3.The Coordinate and Reference Systems of the Australian Continent. 4. A lot of Coordinate and Reference Systems of other Continents. 5. All world-wide used Coordinate and Reference Systems. 6. The German Coordinate and Reference Systems of the old and new Federal States, the 40 Prussian Soldner Land Registers, the German Lagestatus and exact Reference Systems of the German Federal States. Apart from this systems your own coordinate systems and geodetic reference systems can be defined with Helmert or Molodenski (Bursa / Wolf) parameters. You find complete lists of the functions, coordinate and reference systems treated by the DLL in the documentation or direct at the addresses http://www.killetsoft.de/p_gdla_e.htm and http://www.killetsoft.de/p_trdl_e.htm.