The National Archives' collection is made up of records written about Federation, Governors-General, Prime Ministers, Cabinet and Ministries and most of the activities with which the government has been involved. The collection is not open to the public for browsing. Items can be requested for viewing in the reading rooms, and copies of records can be made. Most records over 30 years old are available to the public. Some are released with certain pieces of information deleted. This kind of information includes documents relating to defence and security, private information, and raw census data. Access to information that is culturally sensitivite to indigenous Australians may also be restricted.