CFR /  Title 5  /  Part 332  /  Sec. 332.404 Order of selection from certificates.

An appointing officer, with sole regard to merit and fitness, shall select an eligible for:

(a) The first vacancy from the highest three eligibles on the certificate who are available for appointment; and

(b) The second and each succeding vacancy from the highest three eligibles on the certificate who are unselected and available for appointment.