Judging by the geographical specifications, E16/E17/E18/E19/E20/E21/E22/E23/E24/E25/E26/E27/E28 include the Gserskad and Rdoskad Tibetic varieties of northwestern Sichuan under the areally dominant Amdo Tibetan [adx] entry. But sound changes and other developments from proto-Tibetic effectively exclude the two from being Amdo, and arguably form a separate language ( Sun, Jackson T.-S. 2007 , Sun, Jackson Tianshin 2021 , Sun, Jackson T.-S. 2006 ). See also: Amdo Tibetan [adx].