It is a Roman numeral.
Other meanings: In simplified musical notation, it represents scale step (also degree) - the unit that divides the intervals between the sounds in the scale (each independent sound in the musical sound system). An octave major scale has the first and second steps of the scale...the seventh step; in the next octave, the first and second steps are repeated... ··Seventh level.
The other names of the seven tone levels are tonic, superior tonic, middle tone, subordinate tone, dominant tone, lower middle tone and leading tone (usually represented by Roman numerals IⅡⅢⅣⅤVIⅦ).
Extended information:
Roman numerals are a number used before the introduction of Arabic numerals. Roman numerals use seven Roman letters as numbers, namely I (1), X (10), C (100), M (1000), V (5), L (50), and D (500). Counting method:
When the same numbers are written consecutively, the number represented is equal to the number obtained by adding these numbers, such as III=3;
Small numbers are placed next to large numbers. On the right side, the number represented is equal to the number obtained by adding these numbers, such as Ⅷ=8, Ⅻ=12;
The small numbers (limited to Ⅰ, X and C) are to the left of the large numbers, so The number represented is equal to the number obtained by reducing a large number by reducing a small number, such as IV=4, IX=9;
Drawing a horizontal line on a number means that the number has increased in value by 1,000 times, such as
=5000.
There are several rules for Roman numerals that you must pay attention to. Using Roman numerals to remember larger numbers is cumbersome, so it is no longer commonly used. In Chinese publications, Roman numerals are mainly used for certain codes, such as product models, etc. Computer ASCII code contains the combined Roman numerals 1 to 12.
Use Roman numerals to represent the base of a number. This method is generally to write several Roman numerals in a column. The number it represents is equal to the sum of the numbers represented by each number. But there are exceptions. When the symbol I,
Reference: Roman numerals_Baidu Encyclopedia