Role of Seniority in Selection of Applicants. In matters of appointment to part-time vacancies or full-time vacancies for which there are no full-time applicants, the seniority of part-time applicants shall govern the selection process only where the ability and qualifications of the applicants is relatively equal. Successive part-time vacancies that occur as a consequence of such appointments shall not be subject to the posting provisions of Clause 16.01.