Related Rule
Germany
Practice Relating to Rule 63. Use of Flags or Military Emblems, Insignia or Uniforms of Neutral or Other States Not Party to the Conflict
Germany’s Military Manual (1992) states: “It is prohibited to make improper use of … neutral national flags, military insignia and uniforms.” 
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, § 473.