The Commissioner, in addition to any prescribed leave or leave specified in the Police Award or in an instrument of appointment, may grant leave for a specified period to a police officer, with or without pay, as follows:

(a) additional sick leave for ex-service persons;

(b) leave for defence purposes other than that required by Commonwealth law;

(c) leave due to injury sustained or illness contracted in the course of carrying out duties;

(d) leave for any other reason the Commissioner considers appropriate.