Mongolian O ᠣ

O writes a rounded back vowel and stands fourth in the alphabet. Its most important property is one it shares with the letter that follows it: the script writes o and u with a single shape and does not distinguish them. In practice a Mongolian word containing either is written with the same sign, and the reader supplies the difference from knowledge of the word. This is an inheritance rather than a decision.

The alphabet came to Mongolian from Old Uyghur, and behind that from Sogdian and ultimately from an Aramaic abjad in which a single letter covered the rounded vowels and the labial glide together. Mongolian took the sign as it stood and never subdivided it, so a system with more rounded vowels than its source is written with the source's inventory. Inside a word the shape is a rounded stroke attached to the spine; at the beginning of a word it is preceded by the opening stroke that introduces any vowel; at the end it takes a distinctive tail. Unicode encodes o at U+1823 and u at U+1824, so the two are separate characters in a digital text even though a handwritten page keeps them apart only in the reader's head. That gap between the encoded text and the written page is one of the practical difficulties of putting this script on a screen.

When a writing system does not distinguish two sounds, something else has to. For the rounded vowels of Mongolian that something is the dictionary and the reader's memory, and the arrangement works well enough for a literate community reading its own language. It works less well at the boundaries. Foreign names are the clearest case, because a reader meeting an unfamiliar word has no stored form to fall back on and no way to tell which rounded vowel the writer intended. Scholarly transliteration systems handle this by making the choice explicit, which is why the same Mongolian word can appear in several spellings in Western books, differing precisely at the points the script leaves open. Cataloguers and archivists face the same problem when a personal name has to be filed.

The modern Cyrillic orthography used in Mongolia removes the ambiguity outright, spelling each vowel with its own letter, and that is one of its genuine advantages over the traditional script rather than merely a political fact about the period it was introduced in. The traditional script keeps the ambiguity and keeps a great deal besides: a continuous manuscript tradition, a calligraphic practice, and a body of religious literature that was written in it and has never been fully transferred out of it. The two orthographies answer different needs, and Mongolia today uses both.