Uighur alphabet

The Uighur alphabet is any of the following:

Descendant of Sogdian alphabet, used for texts of Buddhist, Manichean and Christian contents for 700-800 years in East Turkestan. Last known manuscripts are dated the 18th century. Prototype for Mongolian and Manchu alphabets. Also called Old Uighur alphabet.
Modified Arabic alphabet, widely used by modern Uighurs in chinese East Turkestan.
Modified Latin alphabet, used by Uighurs in chinese East Turkestan 15-20 years until late 1980s. Still in use for Internet communications in Uighur.
Modified Cyrillic alphabet, used by Uighurs in former Soviet Republics of Central Asia.