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You can reuse elements from a UML diagram in other UML diagrams. For example, classes can appear on more than one class diagram, and can also appear on multiple use case diagrams.

Relations can also be used in multiple diagrams, but when they are placed on another diagram, the objects attached to them are also placed on the diagram.

The following elements can appear on the following diagrams:


Diagram type


Class diagram, package diagram, use case diagram, sequence diagram (as interaction or lifeline)


Class diagram, package diagram, use case diagram

Data type

Class diagram, package diagram

Primitive type

Class diagram


Class diagram, package diagram


Class diagram, package diagram, sequence diagram (as lifeline)


Class diagram


Class diagram

Association junction

Class diagram


Package diagram, class diagram


Use case diagram, sequence diagram (as interaction or lifeline)

Use case

Use case diagram

Extension point

Use case diagram

All elements available in the sequence diagram can only be used in that diagram.

In order to use an existing element in another diagram just drag the element from the model browser onto the target diagram and drop it there. It is the standard way for using existing elements in multiple diagrams or views.

When using classes and actors in a sequence diagram, they are represented by a lifeline.

Element detail visibility on a diagram

If an element is used on more than one diagram, its display may vary. For example, when a class with attributes and operations that has been created on a class diagram, is used again on a use case diagram, it will not show its attributes and operations. These details are not shown on a use case diagram.

Class with details displayed in a class diagram and in a use case diagram