Ah, getting info from the calendar. That's helpful to know.
In my Bear in Mind addon, I have the Blizzard_Calendar listed as a dependency. I then looked through the UI source code and found how they update and gather calendar info.
You can look in BiM.lua if you like to see how I gather the day's events (just don't straight up copy it
). The relevant code is at the end of the BiM.PlayerLogin function, which then also calls the CheckForCalendarEvents function above that.