U+1F91 "ᾑ" Greek Small Letter Eta with Dasia and Ypogegrammeni Unicode Character

U+1F91 "ᾑ" Greek Small Letter Eta with Dasia and Ypogegrammeni is a polytonic Greek letter representing the vowel eta (η) combined with a rough breathing mark (dasia) indicating an initial /h/ sound and an iota subscript (ypogegrammeni) written below the letter, which in ancient Greek transcription denotes a long diphthong with a silent iota that influences pronunciation and was traditionally used in textual accents. This character, belonging to the Greek Extended block, is primarily employed in classical and liturgical Greek texts to preserve historical orthography and phonetic distinctions, though it is rarely seen in modern Greek writing, which has simplified to monotonic accentuation.