Related Rule
Germany
Practice relating to Rule 66. Non-Hostile Contacts between the Parties to the Conflict
Section C. Definition of parlementaires
Germany’s Military Manual (1992) states:
A cessation of hostilities is regularly preceded by negotiations with the adversary. In the area of operations the parties to the conflict frequently use parlementaires for this purpose … Parlementaires are persons authorized by one party to the conflict to enter into negotiations with the adversary. 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten KonfliktenHandbuch, August 1992, §§ 222 and 223.
The manual adds: “Defectors or members of friendly forces taken prisoner by the adversary have no status as parlementaires nor as persons accompanying parlementaires.” 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten KonfliktenHandbuch, August 1992, § 225.