Qbject-orientated databases model entities as objects in much the same way as do object orientated programming languages. Each object not only contains attributes which define the state of that particular entity, but also the methods (i.e. specialized procedures) for doing various things. For example, in a GIS context a spatial object class might include methods for testing if selected objects overlap or intersect, or if they are adjacent to one another. Groups of similar objects are known as object classes, and individual objects are instances of these classes. The data values themselves are objects. Inheritance is supported i.e. object classes may inherit the properties. data attributes and methods of other classes.