The annual calendar is a watch function that shows at minimum, the day, date and month, often accompanied by the year. While the watch may account for longer and shorter months, it does not take into consideration leap years and therefore must be reset accordingly. Some calendar watches also require a reset each year between the end of February and beginning to March.
Annual Calendar vs Perpetual Calendar
Where annual calendars need to be adjusted per month or at least once in four years, perpetual calendars take different lengths of months and leap years into account. Most perpetual calendar watches only need to be reset at the year 2100. The perpetual watch will regard this as a leap year, but according to calendar rules it is not – only century turnings that can be devided by 400 are leap years.
