Modifier letter left half ring

The modifier letter left half ring ⟨ʿ⟩ is a character of the Unicode Spacing Modifier Letters range (although it is not a modifier but a standalone grapheme). It is used in romanization to transliterate the Semitic letter ayin after it was used by The Encyclopedia of Islam (later the International Journal of Middle East Studies), representing the sound /ʕ/ (a voiced pharyngeal fricative, as in Arabic ع ʿayn). In informal contexts, the backtick ⟨`⟩ or the apostrophe ⟨'⟩ is commonly used as a substitute.