The 610 connector is unique to Australia. The plug consists of three thin and one thicker, nonconnected prongs.
The 610 connector is still rather common in Australian households and is primarily used in wall sockets. Modular, or RJ-15 connectors are popular also.
See also: 431A
This article (or an earlier version of it) contains material from FOLDOC, used with permission. Update as needed.