Gregorian calendar It also specifies its epact relative to 1 January, in contrast with the Julian calendar, which specified it relative to 22 March. The old date was derived from the Greek system: the earlier "Supputatio Romana" specified it relative to 1 January. During the period between 1582, when the first countries adopted the Gregorian calendar, and 1923, when the last European country adopted it, it was often necessary to indicate the date of some event in both the Julian calendar and in the Gregorian calendar, for example, "10/21 February 1750/51", where the dual year accounts for some countries already beginning their
Broadcast calendar Broadcast calendar The broadcast calendar is a standardized calendar used primarily for the planning and purchase of radio and television programs and advertising. Every week in the broadcast calendar starts on a Monday and ends on a Sunday, and every month has either four or five such weeks. Broadcast calendar months thus have either 28 or 35 days. The key link between the broadcast and Gregorian calendars is that the first week of every broadcast month always contains the Gregorian calendar first of the month. For example, if January 1 falls on a Saturday, then the broadcast calendar year would