Oregon Revised Statutes Public Officers and Employees § 242.764

(1) The commission shall prepare and keep a register for each grade and classification in the civil service of all persons whose general average standing upon examination for such grade or classification is not less than the minimum fixed by the rules of the commission, and who are otherwise eligible. Such persons shall take rank upon the register, as candidates, in the order of their relative standing as determined by examination and investigation. Candidates of equal standing shall take rank upon the register according to the order in which their applications were filed. No entrance or promotion register shall be kept in effect for longer than 30 months from the effective date thereof.

(2) The current entrance register shall be headed by the names of persons who have been regular employees and who were laid off from their positions for reasons other than fault or delinquency on their part. The current promotion register shall be headed by the names of persons who have been regular promoted employees and who were demoted from their positions for reasons other than fault or delinquency on their part. The order of the names of such persons shall be such that the name of the person who was last laid off or demoted is first on the register.

(3) Only one entrance register and one promotion register shall exist at any time for each grade and classification in the civil service. No promotion register shall be canceled unless it has been exhausted or has been in existence for at least 30 months. The entrance register shall not be canceled unless it has been exhausted or has been in existence for at least 12 months.