Use case diagram
For information about Use Case Modeling in Modeler, see
Use case modeling overview.
A Use Case Diagram details the possible ways in which a system can be used, that is, the use cases, and the interaction of objects in the system to implement the use cases.
You can create a Use Case Diagram through the context menu of a Package: right-click the Package, and select > > > . Alternatively, if you have configured to display New Diagram in the Quick Access Toolbar, select > . You can also create a Use Case Diagram for a Class, Data Type, Interface or Signal: right-click the item, and select > .
The following sections provide information about how a Use Case Diagram is used in the model. For more information about an item, property or model part, click it.
Shows these dictionary items
Like most diagrams, a Use Case Diagram can show variability items and relationships. See
Overview of variability items and relationships on diagrams.
For most diagram symbols, you can change the presentation of the symbol through the Style view options (See
Style view options - all diagrams), and change the showing of Stereotypes and Tag Definitions through the Stereotypes view options (See
Stereotypes view options for a symbol - all diagrams). When a symbol has additional view options for changing its presentation, this icon 
is shown - to see how the view options can change the presentation, click the icon.
is shown - to see how the view options can change the presentation, click the icon.
Actor
Comment
Constraint
Dependency
Generalization
Use CaseThese items (which are not documented in the reference topics) can also appear on a Use Case Diagram:
• Extend Flow - indicates that a Use Case extends the activity of another. An extend flow points toward the Use Case that is extended. Extend flows can be used to represent alternative courses of action and exceptions. They are modeled as probes (with filled in nodes) on sequence diagrams.
• Frame Box
- provides a way of adding a box or background image to the diagram.
- provides a way of adding a box or background image to the diagram.• Include Flow - indicates that a Use Case includes the activity of another, that is, the included Use Case is a common activity. An include flow points toward the Use Case that is included. Include flows can be used to deal with commonality and complexity in a high level Use Case Diagram. They are modeled as probes (with open nodes) on Use Case Diagrams.
• Note
- provides a way of adding text to the diagram.
- provides a way of adding text to the diagram.• Note Link
- links a Constraint, Comment or Note to an item on the diagram.
- links a Constraint, Comment or Note to an item on the diagram.Properties
A Use Case Diagram has these properties:
Owned by
Class
Data Type
Interface
Model
Package
SignalUsed in these parts of the model
Use Case ModelCan be linked to these dictionary items
Stereotype