You can place user-defined functions in other user-defined functions. You can also configure a user-defined function to be callable from expressions. Callable means that you can place user-defined functions in an expression.
Select one of the following options when you configure a user-defined function:
Callable from any user-defined function, transformation expression, link condition expression, or task expression.
Callable from another user-defined function. Create a private function when you want the function to be part of a more complex function. The simple function may not be usable independently of the complex function.
After you create a public user-defined function, you cannot change the function type to private.
Although you can place a user-defined function in another user-defined function, a function cannot refer to itself. For example, the user-defined function RemoveSpaces includes a user-defined function TrimLeadingandTrailingSpaces. TrimLeadingandTrailingSpaces cannot include RemoveSpaces. Otherwise, RemoveSpaces is invalid.