What is "assaat"

Assaat Datuk Mudo (18 September 1904 – 16 June 1976), known as Mr. Assaat, was born in Banuhampu, West Sumatera, Dutch East Indies (now Indonesia). He was the only President of Yogyakarta-based Republic of Indonesia when became the part of the United States of Indonesia. Reign from December 1949 until August 1950. He and a number of Indonesia founder, fought for the independence of Indonesia from the Dutch.