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Define Parameters

Within the properties of an operation, Activity or Interaction, you can define parameters to control how that object and its subordinate objects behave.

The order or sequence of the parameters in the object properties is reproduced in code. You can set and manage the order using facilities available within the 'Parameters' tab of the 'Properties' dialog for an operation.


Click on an operation in the Browser window or in a diagram.


Design > Element > Editors > Properties Dialog > [select or create an operation] > Parameters

Keyboard Shortcuts

F10 > Parameters

Define the Parameters

The first two fields are in the left-hand panel of the tab, and the remaining fields are in the right-hand panel.



See also


In the 'Parameter' list, overtype the New Parameter text with the new parameter name.


Click on the drop-down arrow and click on:

  • The required data type of the operation, as defined by the code language (data type) or
  • <none> for no type (or you can type in a value manually if you prefer), or
  • 'Select Type' and browse for the appropriate operation classifier (you can add a new one if there are no classifiers that suit)

To add new code language data types that can be displayed in this list, see the Data Types Help topic.

Select Dialog Coding Data Types

Default Value

(Optional) Type a default value for the parameter.


(Optional) Type in the appropriate stereotype name, or click on the Browse. button and select one using the 'Stereotypes for <object name>'. You can select multiple stereotypes, in which case each stereotype is shown on a separate line of the 'Stereotype' field.

Stereotype Selector


(Optional) Type an alternative name or reference for the parameter.


Click on the drop-down arrow and select the way the parameter is passed to a function:

  • In = By Value
  • InOut = By Reference
  • Out = Passed By Reference, but only the return value is significant
  • Return = The parameter is a returned value
Operation Parameters by Reference

Fixed Value

Click on the drop-down arrow and select True, even if the parameter is passed by reference.


Click on the Browse. button to display the 'Multiplicity' dialog, and define the multiplicity of the parameter.

  • Lower bound - Type the lower limit to the number of elements that must be in the collection
  • Upper bound - Type the upper limit to the number of elements allowed in the collection
  • Allow Duplicates - Select the checkbox to indicate that duplicate values are allowed; this field maps to the UML property isUnique, with a value False
  • Multiplicity is Ordered - Select the checkbox to indicate that the collection is ordered
  • OK - Click on this button to save the information and close the dialog


Click on the Browse. button and type any additional notes on the parameter. These notes are unformatted.


  • To organize parameters into the required sequence, and reorganize the display of information, right-click on the background of the 'Parameter' tab or on a specific parameter and select from the same context menu options as for the 'Operations' tab
  • Set the amount of parameter detail to display in a specific diagram using the 'Show Parameter Detail' drop-down list on the 'Features' tab of the 'Properties' dialog for the diagram; the setting applies only to the current diagram, and the default is to show the type only
  • You can set Tagged Values on a parameter, as well as on the parent operation

Learn more