Yang di-Pertuan Agong or Supreme Head or Supreme Head of the Federation "Yang di-Pertuan Agong" or "Supreme Head" or "Supreme Head of the Federation" means the person who is for the time being holding the office of Yang di-Pertuan Agong in accordance with the provisions of the Constitution, and includes the Deputy Supreme Head or a Ruler whenever he is lawfully exercising the functions of the Yang di-Pertuan Agong; ACT 388 - INTERPRETATION ACTS 1948 AND 1967 (CONSOLIDATED AND REVISED 1989) 66. DEFINITIONs.