You are officially divorced once your Certificate of Divorce is issued by the court. Issues like division of property, pensions and debts cannot be changed once the divorce is finalized. This is why it is so important to get legal advice beforehand!
Issues like parenting arrangements and child support may later be changed through a ‘variation application’ if there is a material change in circumstances.
Issues like spousal support may or may not be able to be changed in the future, depending on your situation and the wording in your Corollary Relief Order.