Related Rule
Practice relating to Rule 66. Non-Hostile Contacts between the Parties to the Conflict
Section C. Definition of parlementaires
Switzerland’s Basic Military Manual (1987) defines a parlementaire as a person “who is authorized by one of the belligerents to enter into communication with the other and who advances bearing a white flag”. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 13.