When you look at the law about salvage in the Maritime Transport Act 1994, you will see that some parts of it will start on a date chosen by the Governor-General. You can find these parts in sections 215 to 220 and Schedule 6. The Governor-General will make this date official by using an Order in Council.
The Governor-General's order is a type of law called secondary legislation. If you want to know more about what this means, you can check out Part 3 of the Legislation Act 2019. This act explains what secondary legislation is and how it is published.
You can find more information about the Legislation Act 2019 on the Legislation Act 2019 website, which has details about the publication requirements for secondary legislation.