Note: Emacs binds C-\ to a function that offers
to change the keyboard input method in the multilingual
environment. Viper overrides this binding. However, it is
still possible to switch the input method by typing \
C-\ in the Vi command state and C-z \ C-\ in
the Insert state. Or you can use the MULE menu on the
menubar.
In Vi state, switch to Emacs state; in Emacs state, switch
to Vi state.