ATTR_CALLBACK_DATA (Menu)
| Type: | Menu attribute | 
| Description: | A pointer-width value that is passed to the menu or menu item callback function. The value can be a pointer to user data. | 
| Menu Objects: | Menus, submenus, menu Items. | 
| Data Type: | pointer | 
| Default Value: | NULL | 
| LabWindows/CVI Compatibility: | LabWindows/CVI 3.0 and later | 
