Related Rule
Indonesia
Practice Relating to Rule 5. Definition of Civilians
Indonesia’s Air Force Manual (1990) states: “Unlawful combatants are persons who participate in hostilities without authorization of the belligerent authority, including persons who are neither members of the armed forces nor of a militia.” 
Indonesia, The Basics of International Humanitarian Law in Air Warfare, Indonesian Air Force, 1990, p. 18, § 22.
The Report on the Practice of Indonesia considers that this definition is compatible with the definition provided in Article 50(1) of the 1977 Additional Protocol I. 
Report on the Practice of Indonesia, 1997, Chapter 1.1.