emulation-mode-map-alists is a variable defined in `C source code'.
Its value is

List of keymap alists to use for emulation modes.
It is intended for modes or packages using multiple minor-mode keymaps.
Each element is a keymap alist just like `minor-mode-map-alist', or a
symbol with a variable binding which is a keymap alist, and it is used
the same way. The "active" keymaps in each alist are used before
`minor-mode-map-alist' and `minor-mode-overriding-map-alist'.