In Rational® XDE, it is possible to place association relationships between most shapes and connectors. However, in the new Rational modeling products, you can only place association relationships between classifiers such as classes and use cases because UML 2.0 is stricter than UML 1.4.
In XDE, directed associations are typically owned by the client class, while bidirectional (and undirected) associations are owned by the nearest package or component. Association ownership has changed significantly in UML 2.0. In UML 2.0, associations are always owned by the nearest package or component, while navigable association ends are owned by their client end, not the association itself.
A property object is a new construct in UML 2.0 that does the job of both an Attribute and an AssociationEnd, providing much needed duality between both model elements. Property objects appear as small, red squares in the Model Explorer view, as shown in the figure later in this topic.
In the following figures, the before figures represent XDE, while the after figures represent the same diagram or construct in the Rational modeling products after import.