Spatial units carrying information on land vulnerability are methodologically an important issue. These units should, in the first place, enable the environmental assessments of an intervention. The problem was very much emphasized since the Slovenian legislation has prescribed preparation of vulnerability studies based on ecosystems division of land. The paper suggests that the information on environmental vulnerability should be represented as a “continuous field” data type. It could be derived from different information sources based on different data types. However, the data type should enable further processing based on raster data. Within the Project ONIX-GPOV the specific data base and the specific software have been developed to meet these requirements. Only some basic ideas are described in the article