(every three or four years) at the end of February.
Local variations
As officials adopted it they adapted it.
In the decades after 46 BCE, across the Roman empire,
localities retained features of their old calendars.
The first days of the year and months,
and in some cases the names of the months
were out of synch in the Alexandrian calendar,
the Asian calendar, the Syro-Macedonian calendar,
the Cappadocian calendar, the Cyprus calendar,
and the calendars of the cities of Syria and Palestine.
Moreover, regions on the edges of the empire,
Gaul, Greece, Macedon, the Balkans, and Judea
continued to use their unreformed calendars.
Calends, nundinae, and ides
April Fools day would be
the Aphrodite calends.
The market days were the nundines,
the Sunday of their eight-day week.
March fifteenth was the ides of March,
which Shakespeare’s soothsayer
warned Julius Caesar to beware of.
He knew where he stood,
but it did him little good.
Letters A through H used to mark all days of the year
when the year was divided into nundinæ, cycles of eight days.
Today all days of the year are marked with a letter A though G for each day of the week.
The dominical letter of the year
is determined by which day of the week the first day of January falls on.
This helps with calculations for the liturgical year, to ensure, for example,
that Ash Wednesday falls on a Wednesday, and Easter Sunday falls on a Sunday.
Letters A through H used to mark all days of the year when the year was divided into nundinæ, cycles of eight days. Today all days of the year are marked with a letter A though G for each day of the week. The dominical letter of the year is determined by which day of the week the first day of January falls on. This helps with calculations for the liturgical year, to ensure, for example, that Ash Wednesday falls on a Wednesday, and Easter Sunday falls on a Sunday.
See also in The book of science:
Readings in wikipedia: