Related Rule
Germany
Practice relating to Rule 66. Non-Hostile Contacts between the Parties to the Conflict
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.” 
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 Konflikten – Handbuch, August 1992, § 222.
The manual adds:
Apart from detaching parlementaires, the parties to a conflict may also communicate with each other through the intermediary of Protecting Powers. Protecting Powers are neutral or other states not parties to the conflict which safeguard the rights and interests of a party to the conflict and those of its nationals vis-à-vis an adverse party to the conflict … Particularly the International Committee of the Red Cross may act as a so-called substitute … if the parties to the conflict cannot agree upon the designation of a Protecting Power …
A cease-fire is defined as a temporary interruption of military operations which is limited to a specific area and will normally be agreed upon between the local commanders. It shall regularly serve humanitarian purposes, in particular searching for and collecting the wounded and the shipwrecked, rendering first aid to these persons, and removing civilians. 
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 Konflikten – Handbuch, August 1992, §§ 231 and 232.
Germany’s Soldiers’ Manual (1991) recognizes the white flag as the flag of parlementaires and the flag of surrendering combatants. 
Germany, Taschenkarte, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, Bearbeitet nach ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten – Handbuch, Zentrum Innere Führung, June 1991, p. 6.
Germany’s Military Manual (1992) states that parlementaires “make themselves known by a white flag”. 
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 Konflikten – Handbuch, August 1992, § 223, see also Appendix 1/2.
Germany’s IHL Manual (1996) recognizes the white flag as the flag of parlementaires. 
Germany, ZDv 15/1, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, DSK VV230120023, Bundesministerium der Verteidigung, June 1996, Appendix 1/2, No. 11.
Germany’s Soldiers’ Manual (2006) recognizes the white flag as the flag of parlementaires and the flag of surrendering combatants. 
Germany, Druckschrift Einsatz Nr. 03, Humanitäres Völkerrecht in bewaffneten Konflikten - Grundsätze, Erarbeitet nach ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten - Handbuch, DSK SF009320187, Bundesministerium der Verteidigung, R II 3, August 2006, p. 6.
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 Konflikten – Handbuch, 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 Konflikten – Handbuch, August 1992, § 225.
Germany’s Military Manual (1992) provides: “The commander to whom a parlementaire is sent is not in all cases obliged to receive him.” 
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 Konflikten – Handbuch, August 1992, § 226.