The quality report of a dataset in a geographic information system (GIS) is very important information for a potential user to enable him or her to decide whether the data meets specific demands. Quality is described by a set of the quality parameters completeness, correctness, consistency and accuracy (Veregin, 1989; Lanter and Veregin, 1992). Once they are defined, methods must be applied for checking particular datasets to find data errors and obtain values for the quality parameters. Consistency is a basic requisite for handling geodata. Consistency can be examined at different levels corresponding to the data model. Therefore data modelling will be explained in more detail.