Instructors may be appointed on a full-time or hourly basis in universities and attached units to teach courses or conduct applied practical studies for which a teaching staff member has not been appointed in accordance with this law, or courses requiring particular specialization, from among individuals recognized as specialists in their field on the basis of their experience and works. Instructors may be appointed to positions designated for teaching staff members, ancillary staff or instructors, by a rector, upon the proposal of the Faculty Administrative Board and the Dean in the case of faculties, or the head of department in the case of departments attached to the office of the Rector. They may also be appointed on a part-time (hourly) basis or on a contract basis. Instructors may be appointed to a position designated for a teaching staff member for a maximum two-year period. If, at the end of this period, no teaching staff member has applied for the said position, and the institution deems it appropriate, they may be re-appointed in the same manner. Such appointments are not automatically renewed. Conservatories and schools of higher education may appoint instructors on a regular basis, when necessary.