What is "t-comma"

T-comma is a letter which is part of the Romanian alphabet, used to represent the Romanian language sound , the voiceless alveolar affricate (like ts in bolts). It is written as the letter T with a small comma below and it has both the lower-case (U+021B) and the upper-case variants (U+021A). It is also a part of the alphabets of Gagauz and Livonian.

The letter was proposed in the Buda Lexicon, a book published in 1825, which included two texts by Petru Maior, Orthographia romana sive Latino-valachica una cum clavi and Dialogu pentru inceputul linbei române, introducing ș for and ț for .