Jurisdiction — Territorial — Foreign armed forces — Army and Air Force Exchange Services — United States Military Commissary Stores — Commercial trading — Sale of motor vehicles to United States servicemen stationed in Germany — Claim for breach of competition law — Whether such sales must respect provisions of municipal law — NATO Status of Forces Agreement, 1951, Article II — Supplementary Agreement, Article 11(II) — Distinction between procurement and sale of motor vehicles — The law of the Federal Republic of Germany