How do I map the Ctrl-I key while still retaining the functionality

of the <Tab> key? The Ctrl-I key and the <Tab> key produce the same keycode, so Vim cannot distinguish between the Ctrl-I and the <Tab> key. When you map the Ctrl-I key, the <Tab> key is also mapped (and vice versa). The same restriction applies for the Ctrl-[ key and the <Esc> key.