Which statement regarding the Function property in Client Actions is true?

The statement that setting the Function property to Yes restricts the Action to have only one Output Parameter is accurate. When the Function property is set to Yes in Client Actions, it indicates that the action is designed to behave like a function in programming terms. This means it will return a value (the Output Parameter) and be usable in contexts where a function call is expected. In functional programming concepts, functions typically have a single return value, so this design choice in OutSystems imposes that restriction, simplifying the action's usage and ensuring clearer functional outputs.

The other statements do not accurately reflect the properties or behavior of actions within OutSystems. For example, setting the Function property to No does not inherently restrict the Action's usage to just the module it's defined in, nor does it limit its usability only to Screen Expressions. Additionally, setting the Function property to Yes does not conflict with an action being public; the distinction lies in the action's return capabilities rather than its visibility across modules. Understanding these distinctions is essential for effectively developing and organizing Client Actions in OutSystems applications.