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 of the week closely parallels that of the Latin system and is ordered after the "Seven Luminaries" (七曜 "qī yào"), which consists of the Sun, Moon and the five planets visible to the naked eye. The Chinese seem to have adopted the seven-day week from the Hellenistic system by the 4th century, although by which route is not entirely clear. It was again transmitted to China in the 8th century by Manichaeans, via the country of Kang (a Central Asian polity near Samarkand). The 4th-century date, according to the "Cihai" encyclopedia, is due to a reference to Fan Ning (範寧/范宁),