Per-terminal keymap that overrides all other local keymaps.
If this variable is non-nil, it is used as a keymap instead of the
buffer's local map, and the minor mode keymaps and text property keymaps.
It also replaces `overriding-local-map'.
This variable is intended to let commands such as `universal-argument'
set up a different keymap for reading the next command.
`overriding-terminal-local-map' has a separate binding for each
terminal device.
See Info node `(elisp)Multiple Terminals'.