<P> Much more lasting than the ephemeral month names of the post-Augustan Roman emperors were the Old High German names introduced by Charlemagne . According to his biographer, Charlemagne renamed all of the months agriculturally into German . These names were used until the 15th century, over 700 years after his rule, and continued, with some modifications, to see some use as "traditional" month names until the late 18th century . The names (January to December) were: Wintarmanoth ("winter month"), Hornung, Lentzinmanoth ("spring month", "Lent month"), Ostarmanoth ("Easter month"), Wonnemanoth ("joy - month", a corruption of Winnimanoth "pasture - month"), Brachmanoth ("fallow - month"), Heuuimanoth ("hay month"), Aranmanoth ("reaping month"), Witumanoth ("wood month"), Windumemanoth ("vintage month"), Herbistmanoth ("harvest month"), and Heilagmanoth ("holy month"). </P> <P> The calendar month names used in western and northern Europe, in Byzantium, and by the Berbers, were derived from the Latin names . However, in eastern Europe older seasonal month names continued to be used into the 19th century, and in some cases are still in use, in many languages, including: Belarusian, Bulgarian, Croatian, Czech, Finnish, Georgian, Lithuanian, Macedonian, Polish, Romanian, Slovene, Ukrainian . When the Ottoman Empire adopted the Julian calendar, in the form of the Rumi calendar, the month names reflected Ottoman tradition . </P> <P> The principal method used by the Romans to identify a year for dating purposes was to name it after the two consuls who took office in it, the eponymous period in question being the consular year . Beginning in 153 BC, consuls began to take office on 1 January, thus synchronizing the commencement of the consular and calendar years . The calendar year has begun in January and ended in December since about 450 BC according to Ovid or since about 713 BC according to Macrobius and Plutarch (see Roman calendar). Julius Caesar did not change the beginning of either the consular year or the calendar year . In addition to consular years, the Romans sometimes used the regnal year of the emperor, and by the late 4th century documents were also being dated according to the 15 - year cycle of the indiction . In 537, Justinian required that henceforth the date must include the name of the emperor and his regnal year, in addition to the indiction and the consul, while also allowing the use of local eras . </P> <P> In 309 and 310, and from time to time thereafter, no consuls were appointed . When this happened, the consular date was given a count of years since the last consul (so - called "post-consular" dating). After 541, only the reigning emperor held the consulate, typically for only one year in his reign, and so post-consular dating became the norm . Similar post-consular dates were also known in the west in the early 6th century . The system of consular dating, long obsolete, was formally abolished in the law code of Leo VI, issued in 888 . </P>

Difference between the julian calendar and the gregorian calendar