In addition to having a unique identifier, each menu item in a menu bar or menu has a unique position value. The leftmost item in a menu bar, or the top item in a menu, has position zero. The position value is incremented for subsequent menu items. The system assigns a position value to all items in a menu, including separators. The following illustration shows the position values of items in a menu bar and in a menu.
When calling a menu function that modifies or retrieves information about a specific menu item, you can specify the item using either its identifier or its position. For more information, see Menu Modifications.