overriding-local-map is a variable defined in `C source code'.
Its value is

  • This variable may be risky if used as a file-local variable.

Keymap that replaces (overrides) local keymaps.
If this variable is non-nil, Emacs looks up key bindings in this
keymap INSTEAD OF the keymap char property, minor mode maps, and the
buffer's local map. Hence, the only active keymaps would be
`overriding-terminal-local-map', this keymap, and `global-keymap', in
order of precedence.