Section 20 has effect as if the following subsection were added at the end:
(5) For a non‑national system employee:
(a) who is not a full‑time employee; and
(b) who does not have usual weekly hours of work; and
(c) to whom either of the following subparagraphs applies:
(i) a State industrial instrument applies to the employee, but it does not specify, or provide for the determination of, the employee's ordinary hours of work;
(ii) no State industrial instrument applies to the employee;
the regulations may prescribe, or provide for the determination of, hours that are taken to be the employee's usual weekly hours of work for the purposes of the extended parental leave provisions.