So in the Gregorian calendar the equivalent of the "Solar Cycle" would be 400 years, not 7 x 400 = 2800 years as one might be tempted to believe.) Each ordinary (non-leap) year is assigned a letter in the range A to G which describes what days of the year are Sundays. This is the most likely equivalence between the two systems. This is the cause of some heated debate, especially since some dictionaries and encyclopedias say that a century starts in years that end in 00.This letter is called the "Dominical Letter" ("Sunday Letter") of the year. Furthermore, the change 1999/2000 is obviously much more spectacular than the change 2000/2001.The Gregorian calendar is the one commonly used today.
The following definitions apply to the Gregorian calendar.It was decreed by Pope Gregory XIII in a papal bull, Inter Gravissimas, on February 24, 1582 (shown at right).This bull is named "Inter Gravissimas" after its first two words.For example, the calendars for the years 19 are identical, even when it comes to the date for Easter. Some cultures eschew year counts altogether but name each year after an event that characterized the year.But sometimes a very long time can pass before a calendar can be reused; if you happen to have a calendar from 1940, you won’t be able to reuse it until the year 5280! To most people it is ; to an American it is ; and to a person using the international standard it could be (although a year specified with only two digits does not conform to the ISO standard). However, a count of years from an initial epoch is the most successful way of maintaining a consistent chronology.However, although the last form is frequently seen, it is not allowed by the ISO standard. If you want to be sure that people understand you, you should: In about C. 523, the papal chancellor, Bonifatius, asked a monk by the name of Dionysius Exiguus to devise a way to implement the rules from the Nicean council (the so-called "Alexandrine Rules") for general use. Whether this epoch is associated with an historical or legendary event, it must be tied to a sequence of recorded historical events.