Some Orthodox churches have adopted the Revised Julian calendar for the observance of fixed feasts, while other Orthodox churches retain the Julian calendar for all purposes.
The ordinary year in the previous Roman calendar consisted of 12 months, for a total of 355 days.
The net effect was to add 22 or 23 days to the year, forming an intercalary year of 377 or 378 days.
According to the later writers Censorinus and Macrobius, the ideal intercalary cycle consisted of ordinary years of 355 days alternating with intercalary years, alternately 377 and 378 days long.
This article is about a calendar used for civil and liturgical purposes.