Geo base data is data from official survey agencies that captures and describes the landscape (topography), real estate (land and buildings) within a consistent geodetic spatial reference system that is neutral regarding any specific application (AdV 2005). Examples of such base data in Germany are the Official Topographic-Cartographic Information System (ATKIS), the Official Land Registry Information System (ALKIS) and the Official Survey Marker Information System (AFIS). The three components, AFIS, ALKIS and ATKIS, combine to make up the so-called AAA-Modell.
In addition to geo base data there is also geo expert data, produced by official agencies and institutes on specific topics. Within the IOER Monitor such expert data can be, for example, protected areas specified by the Federal Agency for Nature Conservation (BfN) within their landscape and nature protection programme. Topographic geo base data is required in order to make use of geo expert data.
Note: Although here geo expert data is explicitly distinguished from base data, this distinction is frequently not observed.