4. The bargaining units in any institution in the social affairs sector must be constituted according to the following classes of personnel:(1) nursing and cardio-respiratory care personnel, as defined in section 5;
(2) paratechnical personnel and auxiliary services and trades personnel, as defined in section 6;
(3) office personnel and administrative technicians and professionals, as defined in section 7;
(4) health and social services technicians and professionals, as defined in section 8.