Related Rule
Switzerland
Practice Relating to Rule 121. Location of Internment and Detention Centres
Switzerland’s Basic Military Manual (1987) provides: “Internment shall always take place in premises located on land, where the climate is favourable and where security conditions are sufficient.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 118.
Switzerland’s Aide-Memoire on the Ten Basic Rules of the Law of Armed Conflict (2005) states with regard to prisoner-of-war camps: “Correct behaviour … The camps must be situated at a sufficient distance to combat zones and must be marked.” 
Switzerland, The Ten Basic Rules of the Law of Armed Conflict, Aide-memoire 51.007/IIIe, Swiss Army, issued based on Article 10 of the Ordinance for Organisation of the Federal Department for Defence, Civil Protection and Sports dated 7 March 2003, entry into force on 1 July 2005, Chart of Protective Signs.
With regard to internee camps, the Aide-Memoire also states: “Correct behaviour … The camps must be situated at a sufficient distance to combat zones and must be marked.” 
Switzerland, The Ten Basic Rules of the Law of Armed Conflict, Aide-memoire 51.007/IIIe, Swiss Army, issued based on Article 10 of the Ordinance for Organisation of the Federal Department for Defence, Civil Protection and Sports dated 7 March 2003, entry into force on 1 July 2005, Chart of Protective Signs.
Switzerland’s Regulation on Legal Bases for Conduct during an Engagement (2005) states:
182 Persons who clearly indicate their willingness to surrender may not be attacked. As soon as circumstances permit, they must be searched, disarmed and evacuated from the danger zone. This must be done while constantly ensuring one’s own safety at all times (surveying the battlefield, cover, protection against fire).
185 Mission orders must contain directives for the evacuation and internment of prisoners of war.
189 The final legal status of captured persons is determined by a military tribunal and not by the military unit that took them prisoner. Therefore, the troops treat captured persons with the same respect and in accordance with the same rules as prisoners of war, even when their status is uncertain. 
Switzerland, Bases légales du comportement à l’engagement (BCE), Règlement 51.007/IVf, Swiss Army, issued based on Article 10 of the Ordinance on the Organization of the Federal Department for Defence, Civil Protection and Sports of 7 March 2003, entry into force on 1 July 2005, §§ 182, 185 and 189.
[emphasis in original]