How do I activate and deactivate the child lock on the WAT28400UC?

To activate or deactivate the child lock, touch and hold the Temperature and Finish in buttons simultaneously for approximately 3 seconds until the D symbol appears in the display. When D is lit steady, the child lock is active; when D is blinking, the child lock is active but the cycle selector has been adjusted. Note that the child lock can remain activated until the next cycle start even after switching the machine off. (Page 22)