10.09 Promotions.
   Whenever practicable, vacancies in the classified service shall be filled by promotion, and the Civil Service Rules shall indicate the lines of promotion from each lower to higher grade whenever experience derived in the lower grade tends to qualify for the higher grade. Eligible lists from which promotions are to be made shall be created as provided by the Civil Service Rules, and the appointment of eligibles therefrom shall be made from a certification which contains only the names and addresses of the three highest ranking persons on the eligible list. Appointments to higher positions shall, in such cases as the City Manager shall request, be made after open competitive tests in which persons not in the service of the City may compete as well as applicants for such positions from the lower grades of the service or from other branches thereof. In such cases, appointments shall be made from the three highest eligibles.