General Category - Letter Number

Letter Number is a classification assigned to characters that represent numbers through letters, such as Roman numerals (Ⅰ, Ⅴ, Ⅹ), circled numbers (①, ②), or superscript digits (¹, ²). These characters are distinct from decimal digits (like Arabic 0‑9) and are treated as numeric symbols rather than alphabetic letters, even though they derive from letter forms. The value affects text processing, including sorting, searching, and case mapping, since these characters typically have no lowercase or uppercase variants. It also influences how systems handle numeric conversion, as each such character has a defined numeric value (e.g., Ⅻ equals 12), but they are not used in arithmetic operations like regular digit characters. For programming and font rendering, this classification helps identify glyphs that look like letters but function purely as numerals, ensuring they are not mistakenly processed as normal alphabetic characters.