Related Rule
Switzerland
Practice relating to Rule 66. Non-Hostile Contacts between the Parties to the Conflict
Section A. General
Switzerland’s Basic Military Manual (1987) provides: “Military commanders of both sides may, within the bounds of their authority, contact each other directly in their respective operation zones.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 12(1).
Switzerland’s ABC of International Humanitarian Law (2009) states:
Ceasefire
A ceasefire is an immediate halt or end to hostilities. This military concept refers to both agreements negotiated between the parties to a conflict and the unilateral termination of all military activity by one of the parties, possibly for a specified period of time or in a specified area. 
Switzerland, Federal Department of Foreign Affairs, ABC of International Humanitarian Law, 2009, p. 9.