In process chains, you can use rules as operators to specify how event and function are interlinked. Frequently, these rule representations for displaying logical operators are very complex - this is especially the case when rules are linked to each other. To prevent process chains from becoming too complex due to representations of this kind, you can use the general rule in the EPC or PCD. You can link this general rule operator to a rule diagram illustrating all details of the complex rule (which results in the formation of a hierarchy).