This constant represents the digit equivalent of 1,976 written in the Roman Numeral numeric system. This is an example of a Roman Numeral you might encounter representing the year 1976, so you could theoretically see this Roman Numeral being used in references to the United State's 200th anniversary celebration that was held in 1976.
Larger numbers are written using Roman Numerals by combining the Roman Numeral in sequence with the largest numerals on the left and smaller ones to the right in descending order.
There are special case rules used to subtract values to avoid having numbers with the same Roman Numeral repeated more than three times. In this example case, the 'I" comes before the "V" making the last two digits combine to represent four (instead of using IIII to make four).