Cldr.Calendar.Julian.month_of_year

You're seeing just the function month_of_year, go back to Cldr.Calendar.Julian module for more information.

month_of_year(year, month, day)

month_of_year(year(), month(), day()) :: month()

Calculates the month of the year from the given year, month, and day. It is an integer from 1 to 12.