For the modelling of objects occurring in a com- plex domain (such as CASE), we have developed the INtelligent CAse Conceptual Object Model (INCA- COM). Using the modelling tools offered by INCA- COM, a modeller can describe objects in a natural, Le., understandable way. Although the development of INCA-COM is still in progress, we verify in this pa- per, at least partially, our claims that it allows for a natural way of modelling complex objects. This is done by describing the development of an object- oriented model of a Data-Flow Diagram Editor and its associated objects, using INCA-COM's conceptual tools. This application in modelling served as a test case and has guided us in the further development of other parts of INCA-COM not yet fully specified.