A central problem for the design of knowledge-based systems is the so-called knowledge acquisition bottleneck. Knowledge acquisition is crucial for the quality and efficiency of a planned knowledge-based system. These systems are always based on one or several knowledge bases, whose contents are an influential quality factor for the system's result. For that reason, it is evident that a consistent approach to knowledge acquisition is of great importance. In relation to the problem domain the knowledge-based system is intended for, the knowledge acquisition can be highly problematic. While, for example, in technical problem domains, the access to expert knowledge can usually be achieved in an acceptable manner, the acquisition of medical knowledge for formalisation and usage in an information system is not possible without difficulty