a. Any head of a department established by this charter may appoint, and at pleasure, remove so many deputies as may be provided for by law and determine their relative rank, and may appoint and at pleasure remove a secretary to the department if so provided, and, except as otherwise provided by law, shall assign to them their duties and may by instrument in writing filed in the department designate any deputy to possess any of the powers and exercise such of the duties of the head of the department and for such times and under such conditions as such head of a department may specify.
b. During a vacancy in the office of the head of an administration or a department established by this charter, or whenever by reason of illness or absence from the city such official shall be prevented from attending to the duties of office, the highest ranking deputy not absent of under disability shall act as the head of the administration or department.
c. The head of each mayoral department, including each such department within an administration, shall designate a deputy commissioner of the department or a senior officer reporting directly to the head of the department who shall be responsible for the personnel, management and budget administration functions of the department and for financial planning and management in the areas of payroll, purchasing, vouchering, accounting and related areas assigned by the head of the department.