Calloc is a calendar localization framework for the Emacs calendar. It supplies your locale's official red calendar days, official flag days, other often commemorated days, the days summer and winter time starts and ends (if it is observed in your locale), and localized time formats, names of days, months, hemisphere-seasons, lunar phases, sunset, sunrise and date formats.

Some locales also have extra flag days for official flag days for the flag(s) of national minorities and/or semi-independent regions. (Some minorities have their own locale as well, but it makes sense to add official flag days for their flag to the majority language locales as well since some members of minorities have lost the use of their native language, but still want to celebrate their heritage by flagging with their own flag.) Look in the table of locales currently supported to see which locales include extra flag days.

The Emacs calendar is more useful when it is localized since having your locale's red calendar days and other often commemorated days in the calendar makes it easier to use the calendar for planning appointments. If you have a flag pole, then seeing the official flag days of your locale makes it easier to plan which days to get up early to raise the flag. Seeing in the calendar in advance when to set the clock an hour back or forward at the start and end of summertime (daylight saving time) is also useful for planning even if computers and electronic devices sync their clocks over NTP. In addition, localizing the Emacs calendar makes it more personal and friendly since it speaks your language.

(use-package calloc
 :ensure t
 ;; Load calloc after Emacs' calendar
 :after calendar
 :config
 (setopt calloc-locale "nb_NO"
	 calloc-enable-red-days t
	 calloc-enable-flag-days nil	 
	 calloc-enable-extra-flag-days "Samisk"
	 calloc-enable-commemorated-days t
	 calloc-enable-summertime-days t)))