18. (1) The owner of the copyright in an existing work or the Assignment of copyright.prospective owner of the copyright in a future work may assign to any person the copyright either wholly or partially and either generally or subject to limitations and either for the whole term of the copyright or any part thereof:
Provided that in the case of the assignment of copyright in any future work, the assignment shall take effect only when the work comes into existence.
(2) Where the assignee of a copyright becomes entitled to any right comprised in the copyright, the assignee as respects the rights so assigned, and the assignor as respects the rights not assigned, shall be treated for the purposes of this Act as the owner of copyright and the provisions of this Act shall have effect accordingly.
(3) In this section, the expression "assignee" as respects the assignment of the copyright in any future work includes the legal representatives of the assignee, if the assignee dies before the work comes into existence.
19. No assignment of the copyright in any work shall be valid Mode of assignment.unless it is in writing signed by the assignor or by his duly authorised agent.
20. Where under a bequest a person is entitled to the manuscript Transmission of copyright in manuscript by testamentary disposotion.of a literary, dramatic or musical work, or to an artistic work, and in the work was not published before the death of the testator, the bequest shall, unless the contrary intention is indicated in the testator's will or any codicil thereto, be construed as including the copyright in the work in so far as the testator was the owner of the copyright immediately before his death.
Explanation. — In this section, the expression "manuscript" means the original document embodying the work, whether written by hand or not.
21. (1) The author of a work may relinquish all or any of the Right of author to relinquish copyright.rights comprised in the copyright in the work by giving notice in the prescribed form to the Registrar of Copyrights and thereupon such rights shall, subject to the provisions of sub-section (3), cease to exist from the date of the notice.
(2) On receipt of a notice under sub-section (1), the Registrar of Copyrights shall cause it to be published in the Official Gazette and in such other manner as he may deem fit.
(3) The relinquishment of all or any of the rights comprised in the copyright in a work shall not affect any rights subsisting in favour of any person on the date of the notice referred to in sub-section (1).