b) For a work of joint authorship, the co-authors shall be the first owners of the economic rights. If, however, a work of joint authorship consists of parts that can be used separately and the author of each part can be identified, the author of each part shall be the first owner of the economic rights in the part that he has created. c) For a work created by an author, employed by a natural person or legal entity, in the course of his employment, the first owner of the economic rights shall, unless provided otherwise in a contract, be the employee. d) For an audiovisual work, the first owner of the economic rights shall be the producer, unless provided otherwise in a contract. The co-authors of the audiovisual work and the authors of the pre-existing works included in or adapted for the making of the audiovisual work shall, however, maintain their economic rights in their contributions or pre-existing works, respectively, to the extent that those contributions or pre-existing works can be the subject of acts covered by their economic rights separately from the audiovisual work. §9.22. Presumption Regarding Authorship, Producers of Audiovisual Works and Publishers a) The natural person whose name is indicated as the author of a work in the usual manner shall, in the absence of proof to the contrary, be presumed to be the author of the work. This provision shall be applicable even if the name is a pseudonym, where the pseudonym leaves no doubt as to the identity of the author. b) The person whose name appears on an audiovisual work in the usual manner shall, in the absence of proof to the contrary, be presumed to be the producer of the work. c) In the case of an or pseudonymous work, subject to the provision of subsection (a) of this section, the publisher whose name appears on the work shall, in the absence of proof to the contrary, be presumed to represent the author and, in this capacity, shall be entitled to exercise and enforce the moral and economic rights of the author. This presumption shall cease to apply when the author reveals his identity. §9.23. Assignment, Relinquishment and Licensing of Authors’ Rights a) Subject to this section, copyright shall be transmissible by assignment, license, and testamentary disposition or by operation of law, as movable property. b) An assignment, license or testamentary disposition of copyright may be limited so as to apply only to some of the acts which the owner of the copyright has the exclusive right to control, or to a part only of the period of the copyright, or to a specified country or other geographical area. c) Any assignment of copyright and any exclusive license to do an act subject to authorization by the owner of copyright shall be in writing signed by or on behalf of the assignor or licensor, as the case may be. 28