(c) in so far as is strictly necessary when, for reasons of extreme urgency brought about by events unforeseeable by the entity, the goods or services could not be obtained in time by means of open or selective tendering procedures;
(d) for additional deliveries by the original supplier that are intended either as replacement parts or continuing services for existing supplies, services or installations, or as the extension of existing supplies, services or installations, when a change of supplier would compel the entity to procure equipment or services not meeting requirements of interchangeability with already existing equipment or services, including software to the extent that the initial procurement of the software was covered by this Chapter;
(e) when an entity procures a prototype or a first good or service that is developed at its request in the course of, and for, a particular contract for research, experiment, study or original development. When such contracts have been fulfilled, subsequent procurements of goods or services shall be subject to Articles 1008 (Tendering Procedures) through 1015 (Submission, Receipt and Opening of Tenders and Awarding of Contracts). Original development of a first good may include limited production in order to incorporate the results of field testing and to demonstrate that the good is suitable for production in quantity to acceptable quality standards. It does not extend to quantity production to establish commercial viability or to recover research and development costs;
(f) for goods purchased on a commodity market;
(g) for purchases made under exceptionally advantageous conditions that only arise in the very short term. This provision is intended to cover unusual disposals by firms which are not normally suppliers; or disposal of assets of businesses in liquidation or receivership. It is not intended to cover routine purchases from regular suppliers; and
(h) for a contract awarded to the winner of an architectural design contest, on condition that the contest
(i) has been organized in a manner that is consistent with the principles of this Chapter, notably as regards the publication, in the sense of Article 1010 (Invitation to Participate), of an invitation to suitably qualified suppliers to participate in the contest,
