As a running example for all patterns dealing with mappinh inheritance we use a part of a so called partner system. A Party is any form of person (natural person or institution) our company has to work with. Customers are Parties as well as Employees. When it comes to Employees, we distinguish between SalariedEmployees and FreelanceEmployees. This results in the following object diagram.

We did not add all attributes needed for a real life application but insert only as many attributes as are needed to demonstrate the different mapping patterns that we discuss. Therefore we do not use any complex attributes or relationships. For our example we assume that none of the classes is an abstract base class. All five classes may have instances.