ORTWIN is a program for the state-wide inquiry of the localities in Germany. It finds postal zip codes, telephone pre selections, coordinates, it performs perimeter searches and distance calculations. The program determines municipal codes, local center points, car license codes, topographic maps and more. It arranges localities hierarchically into the structures federal country, administrative district, rural district, town, municipality, local quarter and domicile. In a radius around a place or around a postal code area covered localities and postal areas can be clearly represented by a comfortable perimeter search. They can also be arranged in a list, stored as a file and printed. For the local inquiries and perimeter searches a data base with more than 60.000 geo coded localities is available. The program represents local data, determined by local inquiries and perimeter searches, in graphic overviews and data lists. The program supports conversions between different coordinate systems and the distance calculation between the places. It calculates with Gauss Krueger coordinates and Geographic Coordinates referring to the Potsdam Datum (Bessel ellipsoid with central point Rauenberg). It also works with UTM coordinates, which refer to the datum ETRS89 (GRS80 / WGS84, geocentric). The functionality of the program is described in a detailed electronic manual. The program can be run on most common networks and it is possible to use Terminal Services on WINDOWS Servers. The client installations are done automatically.