U+02D1 MODIFIER LETTER HALF TRIANGULAR COLON

U+02D1 was added to Unicode in version 1.1 (1993). It belongs to the block Spacing Modifier Letters in the Basic Multilingual Plane.

This character is a Modifier Letter and is commonly used, that is, in no specific script.

The glyph is not a composition. It has a Neutral East Asian Width. In bidirectional context it acts as Left To Right and is not mirrored. In text U+02D1 behaves as Alphabetic regarding line breaks. It has type OLetter for sentence and ALetter for word breaks. The Grapheme Cluster Break is Any.

The Wikipedia has the following information about this codepoint:

In linguistics, vowel length is the perceived duration of a vowel sound. Often the chroneme, or the "longness", acts like a consonant, and may have arisen from one etymologically, such as in Australian English. While not distinctive in most other dialects of English, vowel length is an important phonemic factor in many other languages, for instance in Finnish, Fijian, Japanese, Old English, and Vietnamese. It plays a phonetic role in the majority of dialects of English English, and is said to be phonemic in a few other dialects, such as Australian English and New Zealand English. It also plays a lesser phonetic role in Cantonese, unlike other varieties of Chinese.

Many languages do not distinguish vowel length phonemically, and those that do usually distinguish between short vowels and long vowels. There are very few languages that distinguish three phonemic vowel lengths, for instance Luiseño and Mixe. However, some languages with two vowel lengths also have words where long vowels appear adjacent to other short or long vowels of the same type, e.g. Japanese hōō "phoenix", Estonian jäääärne "(on the) edge of the ice", or Ancient Greek ἀάατος [a.áː.a.tos] "inviolable". Some languages that do not ordinarily have phonemic vowel length but do permit vowel hiatus may similarly exhibit sequences of identical vowel phonemes that yield phonetically long vowels, such as Georgian გააადვილებ [ɡa.a.ad.vil.eb] "you will facilitate it".