What does "RRC" stands for?

How the calendar works

• Each year is divided into twelve 30-day months, four seasonal days, one "Median day" which marks the middle of the year and one "Leap day" when the year is a leap year; this is put at the end of the year.
• Each month is divided into three 10-day weeks.
• Seasonal days, median day and the leap day does not have a weekday name.
• Names for the months are taken from the French Republican Calendar, with Nivôse being the first month.
• Unlike the French Republican Calendar, Nivôse 1 is the same day as Gregorian calandar January 1st.
• To prevent confusion with the Gregorian calendar and the original French Republican Calendar, a prefix like "RRC" can be added before the date, and Gregorian month names can be used.
• The Median Day, the Leap Day and the four seasonal days don't belong to any month; when written in concise format, they're written as: "P" for Day of Spring (Printemps), "É" for Day of Summer (Éte), "A" for Day of Autumn (Automne), "H" for Day of Winter (Hiver), "M" for Median Day and "X" for Leap day