Function: set-input-meta-mode

Enable or disable 8-bit input on TERMINAL.
If META is t, Emacs will accept 8-bit input, and interpret the 8th
bit as the Meta modifier.

If META is nil, Emacs will ignore the top bit, on the assumption it is

Otherwise, Emacs will accept and pass through 8-bit input without
specially interpreting the top bit.

This setting only has an effect on tty terminal devices.

Optional parameter TERMINAL specifies the tty terminal device to use.
It may be a terminal object, a frame, or nil for the terminal used by
the currently selected frame.

See also `current-input-mode'. (fn META &optional TERMINAL)