Related Rule
Germany
Practice relating to Rule 66. Non-Hostile Contacts between the Parties to the Conflict
Section A. General
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 KonfliktenHandbuch, 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 KonfliktenHandbuch, August 1992, §§ 231 and 232.