In New Zealand we can ban a movie, game or other publication if its availability is likely to be injurious to the public good due to how it deals with sex, horror, crime, cruelty and violence.
Other systems use other tests, for example the NZ Broadcasting Standards Authority uses a test of "good taste or decency". The Australian Classification Code talks about content that might "offend against the standards of morality, decency and propriety generally accepted by reasonable adults".
The M classification means that something is unrestricted and recommended for mature audiences 16 years and over.
The wording of the M classification can sometimes be confusing partly because two other classifications also refer to people "16 years and over": R16 means "Restricted to people 16 years and over" and RP16 means "Restricted to people 16 years and over unless accompanied by a parent or guardian".
The name of the committee set up by the government to review our classification laws in the 1980s was the Ministerial Committee of Inquiry into Pornography.
The correct answer refers to 'pornography' in the title as many people were concerned about this at the time, but the scope of the review was much wider - looking at censorship issues in general, reviewing the existing classificaion laws and coming up with recommendations for a new law.
Find out more about why classification works the way it does
The Office of Film and Literature Classification is not responsible for enforcing the classification system.
Police, Customs and the Censorship Compliance Unit are all responsible for enforcing the law. Our role is to classify publications and provide information about the system.
Singapore's Media Development Authority uses an R21 age restriction for some films.
By law, the highest age-restriction we can assign in New Zealand is R18. A restriction to 18 year-olds is also the highest classification in Australia and the UK. However, all of the agencies on this list can also ban films or require cuts to be made to films.
Our first film classification law was the Cinematograph-film Censorship Act of 1916.
Some other names for historical film classification laws in New Zealand are Films Act 1983, the Video Recordings Act 1987 and the Cinematograph Films Act 1961.
Find out more about the history of censorship on our timeline
We can't classify broadcast TV, live performances or statues.
We can't classify broadcasts on radio or TV because this is covered by the Broadcasting Act 1989. Live shows that are filmed and then later distributed on DVD or some other media are 'publications' and so can be classified, but a performance as it is being performed cannot be classified. What about statues or sculptures? A statue can't be classified unless it has "printed or impressed upon it, or otherwise shown upon it, 1 or more...images, representations, signs, statements, or words".
Find out more about why classification works the way it does