[ REPUBLIC OF ANGOLA 6. The patent holder shall be entitled to demand equitable remuneration, as well as supervision of the exploitation of the invention involving, inter alia, the manufacture, sale and use of the subject matter of the invention. Article 12 (Invention occurring while an employment contract is in force) 1. Inventions and improvements carried out during the period of validity of an employment contract for research in Angola, in which the inventive activity was planned or resulted from the very nature of the work performed, shall belong exclusively to the employer entity. 2. Inventions that have occurred during the period of validity of an employment contract must be patented in Angola and this circumstance, together with the name of the inventor, shall appear on the patent application. 3. Where a worker uses his own resources, equipment or other material means, he shall have exclusive ownership of the invention. 4. Where the employer entity and the worker have contributed equally to the making of an invention, said invention shall be owned jointly, with the employer enterprise having the right to exploit it and the worker having the right to the remuneration set, unless otherwise provided by the parties. 5. A joint invention patent shall be exploited by the employer within one year of its grant, failing which it shall become the exclusive property of the worker. Article 13 (Nullity of a patent) A patent shall be null and void where: a) its subject matter does not meet the conditions set out in Article 3; b) it is established that its subject matter was not patentable under the terms of Article 4; c) it has been granted contrary to the rights of third parties; d) it is established that the title does not correspond to its true subject matter; e) one of the legal formalities stipulated in this Law has been omitted during its processing.