Related Rule
Germany
Practice Relating to Rule 67. Inviolability of Parlementaires
Germany’s Military Manual (1992) provides:
Parlementaires and the persons accompanying them, e.g. drivers and interpreters, have a right to inviolability …
When entering the territory of the adversary, parlementaires and the persons accompanying them shall not be taken prisoner or detained. The principle of inviolability shall apply until they have safely returned to friendly territory. It does not require the adverse party to completely cease fire in a sector where a parlementaire arrives. 
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, §§ 223 and 224; see also § 1034 (protection of cartel ships).