Higher grade duty at Healthe Care

I work in a hospital run by Healthe Care. How does the higher grade duty work?
Clause 22 of the Healthe Care Pty Ltd (New South Wales Hospitals) and the NSWNMA/ANMF NSW Branch Enterprise Agreement 2017 sets out that, if acting up in a higher graded position, you should receive for the period of acting the minimum payment for the higher position. Note that if rostered in advance, the period of acting must be for more than three consecutive days to activate the payment unless you are required to be in charge of the hospital during the period.