In a user interface, ... after a command means that the user needs to enter extra information before the command can execute. It is also used to signify that an operation may take some time, as in "Please wait...". In a GUI environment, clicking on a menu item with ... after the name means another dialog box will open which requires more actions from the user. A typical example is the Run... in the Microsoft Windows Start menu and the List of Values field in Oracle ERP applications.
If a command requires additional information to complete its intended action, and you use a dialog box to supply that information, follow the command with an ellipsis