Legal time ought to be used in official and business affairs.
The time law can be understood as a continuation of legal practice going back to 1893 when mean solar time at 15 degree eastern longitude was laid down as legal time for the German Reich. Before that date numerous regulations existed which established the use of local times throughout the country. In contrary, the use of the Gregorian calendar had already found common acceptance for several centuries. To make it clear, daylight saving time begins on the last Sunday of March and ends on the last Sunday of October in each year. The Physikalisch-Technische Bundesanstalt PTB is entrusted by the Time Act to realise and disseminate legal time to the public.