CITROEN DS3 Owner's Handbook Manual page 30

Total distance recorder
System which measures the total distance
travelled by the vehicle during its life.
The total and trip distances are displayed for
thirty seconds when the ignition is switched off,
when the driver's door is opened and when the
vehicle is locked or unlocked.
Trip distance recorder
System which measures a distance travelled
during a day or other period until it is reset to
zero by the driver.
With the ignition on, press the button until
zeros appear.
Instruments and controls
Lighting rheostat
System for manual adjustment of the brightness
of the instruments and controls in relation to the
exterior brightness.
Activation
When the lighting is on:
press the button to change the brightness
of the instruments and controls,
when the level of brightness required is
reached, release the button.
Deactivation
When the lighting is off, or in day mode on
vehicles fitted with LED lamps, pressing the
button does not have any effect.