1. Evidence of economic operators' technical abilities may, as a general rule, be furnished by one or more of the following means, according to the nature, quantity or importance and use of the works, supplies or services:

(a)

(i) a list of the works carried out over the past five years, accompanied by certificates of satisfactory execution for the most important works. These certificates shall indicate the value, date and location of the works and shall specify whether they were carried out according to the rules of the trade and properly completed. Where appropriate, the competent authority shall submit these certificates to the contracting authority/entity directly;

(ii) a list of the principal deliveries effected or the main services provided, as a general rule, in the past five years, with the sums, dates and recipients, whether public or private, involved. Evidence of delivery and services provided shall be given:

- where the recipient was a contracting authority/ entity, in the form of certificates issued or countersigned by the competent authority,

- where the recipient was a private purchaser, by the purchaser's certification or, failing this, simply by a declaration by the economic operator,