Determination of the day of the week not a Gregorian leap year, (but 19 in the Julian column indicates that it "is" a Julian leap year, as are all Julian "x"00 years). 20 indicates that 2000 is a leap year. Use Jan and Feb only in leap years. For determination of the day of the week (1 January 2000, Saturday) For determination of the dominical letter (2000, BA) For determination of the doomsday (2000, Tuesday) Note that the date (and hence the day of the week) in the Revised Julian and Gregorian calendars is the same from 14 October 1923 to 28 February AD 2800 inclusive and
Names of the days of the week seven-day week spread throughout the Roman Empire in Late Antiquity. By the 4th century, it was in wide use throughout the Empire, and it had also reached India and China. The Greek and Latin names are as follows: Except for modern Portuguese and Mirandese, the Romance languages preserved the Latin names, except for the names of Sunday, which was replaced by "[dies] Dominicus (Dominica)", i.e. "the Lord's Day" and of Saturday, which was named for the Sabbath. In Corsican, the Saturday is known either by Sabatu or De Sadorn. Early Old Irish adopted the names from Latin, but introduced separate