ComposeKey

The Compose(key) on Sun Type 6/7 keyboards (standard keyboards at the institute)

http://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Compose_key_on_Sun_Type_5c_keyboard.jpg/220px-Compose_key_on_Sun_Type_5c_keyboard.jpg (Broken link) 

allows you to type characters not available by ordinary key presses, such as Æ, ṅ, Ð, and so on.

In order to produce such characters, you first press Compose followed by additional two keystrokes which compose the character, for instance:

• Compose, ", a → ä

or

• Compose, ,, c → ç

Here's a rather incomplete list of possible characters:

Please refer to http://en.wikipedia.org/wiki/Compose_key for more information.