Wikipedia says:
The Australian Classification Board was created in 1970 to classify or rate all films (and later in 1994, video games) that came into Australia. In the early years of the system, beginning on November 15, 1971, there were four ratings:
G for General Exhibition, carried over from the previous ratings system
NRC Not Recommended for Children (previously X, A or Not Suitable for Children. This later became PG for Parental Guidance)
M for Mature Audiences (Previously SOA or Suitable Only for Adults. This later became M 15+ from the late 1980s until 2005)
R for Restricted Exhibition (later became R 18+ in the late 1980s)Australia is weird.
That’s not even accurate. They forgot MA 15+.