From teletypewriter

* produces an ASCII escape character. It may be used to exit menus or modes.
* is a backtick or grave accent, also formerly backspaced over letters to write non-English languages; on some systems it is used as an opening quote. The single quote ' is normally used for an acute accent.
* is the tilde, an accent backspaced and printed over other letters for non-English languages. Nowadays the key does