[ REPUBLIC OF ANGOLA Article 14 (Lapse of a patent) 1. A patent shall lapse: a) on the expiration of the term of legal protection; b) where it is waived by its holder or his successors; c) where it has not begun to be effectively and regularly exploited in Angola within four years of being granted; d) where its exploitation has been interrupted for more than two years, save in the event of proven force majeure; e) where fees have not been paid, save where the patent owner requests its revalidation within six months of the date on which the fee should have been paid. 2. For the purposes of paragraph (c) of this Article, regular and effective exploitation of a patent shall mean exploitation of the patent either by its holder or by a third party through the grant of a license. CHAPTER III Utility models and industrial designs Article 15 (The concept of utility models) 1. Any new arrangement or form obtained in or introduced into objects such as tools, work implements or utensils that improve or increase the conditions for their use and their usefulness, shall be regarded as a utility model. 2. Protection shall be granted exclusively to the particular new form that makes it possible to increase and improve the utility and utilization of the objects for which it is intended. Article 16 (Concept of industrial design) 1. Any three-dimensional form, whether or not it is associated with a line or colors that may be used as a type in the manufacture of an industrial or handcrafted product, shall be taken to be an industrial design. 2. Any new arrangement or set of lines or colors that may be applied, for an industrial or commercial purpose, in the ornamentation of a product by any