Yat or Jat (, ) is the name of the thirty-second letter of the old Cyrillic alphabet, or of the sound it represents. Its name in Old Church Slavonic is y?t? () or yat? (????), in Bulgarian yat (??) or e dvoyno (? ??????, double e), in Russian and Ukrainian yat? (???), in Serbian yat (jat, ???), Croatian jat. In the common scientific Latin transliteration for old Slavic languages, the letter is represented by e with caron: (taken from Czech alphabet). The yat represented a Common Slavic long vowel. It is generally believed to have represented the sound , which was a reflex of earlier , or . That the sound represented by yat developed late in the history of Common Slavonic is indicated by its role in the second palatalization of the Slavonic velars. It is significant that from the earliest texts, there is considerable confusion between the yat and the Cyrillic io