The global constant DTU_gc_tziTimeZoneCET defines the time zone as well as the switch between summer and standard time of the Central European EU countries. The switch is done according to the following rules: The switch to summer time (CEST) takes place on the last Sunday of March. The clock is set ahead by one hour at 2:00 a.m.. The switch to standard time (CET) takes place on the last Sunday of October. The clock is set back by one hour at 3:00 a.m..