Working With Model Items and Diagrams > Working with diagrams > Diagram types > Sequence diagram
  
Sequence diagram
For information about Object Interaction Modeling in Modeler, see Object interaction modeling overview.
A Sequence Diagram is a graphical description of a Class, Event, Interface, Operation or Use Case. You use it to show the interactions which occur between the objects. The diagram includes statements, objects and stimuli:
• Each statement describes the processes which occur written in a form of structured English (additional view options can be used to show line numbering and loop connections - known as construct balancing); statements are written down the left hand margin of the diagram; the vertical time axis is nonlinear and can be regarded as event driven.
• Objects and boundaries - declared across the top of the diagram and modeled as vertical lines: objects can be Actors, Instances, Parts, Ports, Interface Devices, Packages and Subsystems. The order in which objects are placed on the diagram is not significant; however, they should be arranged for maximum clarity.
• Stimuli, in the form of messages and probes between objects which are drawn automatically.
You can create a Sequence Diagram through the context menu of a Package: right-click the Package, point to UML, point to Behavior, and then click Sequence Diagram. You can also create a Sequence Diagram for an Event, Operation or Use Case: right-click the item, point to New, and then click Sequence Diagram.
You must use a Sequence Diagram to create the following model items:
Statement
Timing Constraint
The following sections provide information about how a Sequence 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 Sequence Diagram can show variability items and relationships. Tell me more...
For most diagram symbols, you can change the presentation of the symbol through the Style view options ( tell me more...), and change the showing of Stereotypes and Tag Definitions through the Stereotypes view options ( tell me more...). 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.
Actor
Attribute(as Part or Port instance)
Comment
Constraint
Dependency
Event (instance of)
Instance
Interface Device
IO Flow
Operation (instance of)
Package
Role (as Part or Port instance)
Slot (on Instances)
Statement
Subsystem
Timing Constraint
Use Case(instance of as a Probe)
These items (which are not documented in the reference topics) can also appear on a Sequence Diagram.
• Frame Box - provides a way of adding a box or background image to the diagram.
• Note - provides a way of adding text to the diagram.
• Note Link - links a Constraint, Comment or Note to an item on the diagram.
Properties
A Sequence Diagram has these properties:
• Description
• Full Name
• Last Changed By
• Last Changed On
• Name
• Page Reference
• Type
• Visibility
Owned by
Class
Event
Interface
Model
Operation
Package
Use Case
Used in these parts of the model
Object Interaction Model
Can be linked to these dictionary items
Stereotype
* 
Like other diagrams in a Model, a Constraints Diagram can be linked to an Activity Partition, Comment, Frame Box, General Node, General Flow, General Flow Diagram Node, Constraint (applied), General Flow Diagram Flow or Swimlane.