Roman numeral

The R. n. appears in three places when writing a date: 1) in the French Revolutionary Calendar to designate a) which decade the day of the month fell in; b) which year of the Revolution the year was; the date description has these R. n. in PS-RULE DP1; 2) the R. n. may also follow the given name of the British monarch in giving the regnal year; the R. n. appears as a variation to the ordinal form of a postpositive title phrase of a personal name phrase in PS-RULE [PS13].