54As the Court has already held (Windsurfing Chiemsee, paragraph 25, Linde, paragraph 73, and Libertei, paragraph 52), Article 3(1)(c) of the Directive pursues an aim which is in the public interest, namely that such signs or indications may be freely used by all. Article 3(1)(c) therefore prevents such signs and indications from being reserved to one undertaking alone because they have been registered as trade marks.