A user-defined action that has been defined only in terms of its name and possibly its
arguments as well, without any internal action lines. A stub action serves as a convenience
to anyone referencing it in the test editor, who will see that the action is defined, and
also finds the calling action line automatically populated with the correct argument
A stub action may serve as a placeholder for a user-defined action to be
created at a later time. It may also function as a "front end" for a user-scripted action, given that such actions
cannot automatically make themselves known to the editor.