Interesting question, David. The term of each Parliament can be divided into sessions. When a session of Parliament is formally closed (other than to call an election), it is said to be prorogued. The Governor-General, acting on the advice of the Prime Minister, prorogues Parliament.
When Parliament is prorogued, the Notice Paper—which lists all business that is before the Senate and House of Representatives—is cleared. Senate committees can be empowered to meet after a prorogation and bills introduced in the previous session may be revived in the new session.