1. A method for flexibly storing and accessing hierarchical application data, comprising: providing classes including a hierarchy base class with functionalities for accessing hierarchical relationships; at least one hierarchy subclass that is derived from the hierarchy base class; and at least one application class; instantiating objects including at least one hierarchy object of the at least one hierarchy subclass; and at least one application object of the at least one application class; linking each application object to at least one hierarchy object, and vice versa, such that hierarchically related application objects have access to each other via the functionalities provided by the hierarchy base class without being derived therefrom.