War and neutrality — War in general — Prisoners of war — Hague Regulations respecting the Laws and Customs of War on Land — Spies — Whether member of armed forces operating out of uniform a spy — Whether spies treated as prisoners of war — Whether member of the armed forces in disguise acting as saboteur spy — Whether such member of armed forces to be treated as a prisoner of war — Geneva Convention on Prisoners of War, 1949 — Whether such member a prisoner of war within the meaning of Article 4 of the Geneva Convention — The Law of Singapore