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(emacs)Named ASCII Chars

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Named ASCII Control Characters
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   <TAB>, <RET>, <BS>, <LFD>, <ESC> and <DEL> started out as names for
certain ASCII control characters, used so often that they have special
keys of their own.  Later, users found it convenient to distinguish in
Emacs between these keys and the "same" control characters typed with
the <CTRL> key.

   Emacs distinguishes these two kinds of input, when the keyboard
reports these keys to Emacs.  It treats the "special" keys as function
keys named `tab', `return', `backspace', `linefeed', `escape', and
`delete'.  These function keys translate automatically into the
corresponding ASCII characters _if_ they have no bindings of their own.
As a result, neither users nor Lisp programs need to pay attention to
the distinction unless they care to.

   If you do not want to distinguish between (for example) <TAB> and
`C-i', make just one binding, for the ASCII character <TAB> (octal code
011).  If you do want to distinguish, make one binding for this ASCII
character, and another for the "function key" `tab'.

   With an ordinary ASCII terminal, there is no way to distinguish
between <TAB> and `C-i' (and likewise for other such pairs), because
the terminal sends the same character in both cases.