Why does neovim not let me map <C-m> and <C-i>?

[slugbyte]

If I map <C-m> to anything, anytime I'm in normal mode if I press <Enter>, it will trigger the <C-m> mapping... this makes <c-m> basically unusable to me. does anyone know why this is?

I also have had trouble mapping <C-i> to anything. If i inspect the map it will show that its been remaped, but when I trigger it, nothing happens. does anyone know why this is?