Numpad keys managing backlight
They are /, *, – and + keys, combined with Fn key.
Fn key + « / » allows you to loop through the different backlight modes. Not very useful on everyday use, except to discover the available modes.
Fn key + « * » allow you to switch on or off the backlight.
Fn key « – » and « + » allow you to lower or rise the brighness of backlight.