31.1. A candidate inventory may be used for a period of 2 years from the date of its constitution. Notwithstanding the foregoing, the period for using the candidate inventory may be extended, each extension corresponding to 1 year, by taking the following criteria into consideration:
(1) the number of applicants eligible for the candidate inventory or whose eligibility is established by the evaluation, as the case may be, who have not yet been declared qualified;
(2) the number of positions likely to be filled after competitions are held from the candidate inventory; and
(3) the appropriateness of the evaluation procedure used in relation to the nature of the position.