U+1843 "ᡃ" Mongolian Letter Todo Long Vowel Sign Unicode Character

U+1843 "ᡃ" Mongolian Letter Todo Long Vowel Sign is a diacritical mark used in the Todo script, a variant of the traditional Mongolian alphabet historically employed by the Oirat and Kalmyk peoples. Its primary function is to extend the length of a preceding vowel in a syllable, altering pronunciation for linguistic precision in representing long vowel sounds within Todo Mongolian orthography. This character belongs to the Unicode block for Mongolian, where it serves as a modifier rather than an independent letter, and it is typically written as a thin, vertical line attached to the upper right of a base character. The Todo script itself was developed in the 17th century to more accurately transcribe spoken Oirat, and this vowel sign remains a key component in preserving the phonetic distinctions of that language in digital text.