The mode indicator, located at the bottom center of the LCD, shows the DT402/DT400 series throttles' current mode of operations.
The DT400 automatically defaults to the Fn mode & returns to this mode whenever the EXIT Key is pressed. The Mode indicator usually shows what the numeric keys are associated with. For example, in Fn mode, any entry on the numeric keypad will affect functions. In Sw mode, keypad entries will change turnouts and in Lo mode, entries on the keypad will enter loco address numbers, etc.