When assigned to a menu item, it inserts a tear off bar into the menu (a horizontal broken line). Activating that item tears off the menu. If the menu item has a label, it is shown instead of the broken line. If used outside menus, this command does nothing. Examples:

AddToMenu WindowMenu
+ I "" TearMenuOff

AddToMenu RootMenu
+ I "click here to tear me off" TearMenuOff