Germanic calendar inspired by the Julian calendar, introduced a purely solar reckoning with a year having a fixed number of weeks (52 weeks or 364 days). This necessitated the introduction of "leap weeks" instead of Julian leap days. The old Icelandic calendar is not in official use any more, but some Icelandic holidays and annual feasts are still calculated from it. It has 12 months, of 30 days broken down into two groups of six often termed "winter months" and "summer months". The calendar is peculiar in that each month always start on the same day of week. This was achieved by
Gregorian calendar to number the days sequentially with no gaps, and 29 February is typically considered as the leap day. Before the 1969 revision of the Roman Calendar, the Roman Catholic Church delayed February feasts after the 23rd by one day in leap years; Masses celebrated according to the previous calendar still reflect this delay. Calendar cycles repeat completely every 400 years, which equals 146,097 days. Of these 400 years, 303 are regular years of 365 days and 97 are leap years of 366 days. A mean calendar year is days = 365.2425 days, or 365 days, 5 hours, 49 minutes and