control character codes. For example, the key labelled "Backspace" typically produces code 8, "Tab" code 9, "Enter" or "Return" code 13 (though some keyboards might produce code 10 for "Enter").

Many keyboards include keys that do not correspond to any ASCII printable or control character, for example cursor control arrows and word processing functions. The associated keypresses are communicated to computer programs by one of four methods: appropriating otherwise unused control characters; using