All told, the prefix keys in Emacs are @kbd{C-c}, @kbd{C-h},
@kbd{C-x}, @kbd{C-x @key{RET}}, @kbd{C-x @@}, @kbd{C-x a}, @kbd{C-x
-n}, @w{@kbd{C-x r}}, @kbd{C-x v}, @kbd{C-x 4}, @kbd{C-x 5}, @kbd{C-x
-6}, @key{ESC}, and @kbd{M-g}. (@key{F1} and @key{F2} are aliases for
+n}, @w{@kbd{C-x r}}, @kbd{C-x v}, @kbd{C-x 4}, @kbd{C-x 5}, @kbd{C-x 6},
+@key{ESC}, @kbd{M-o} and @kbd{M-g}. (@key{F1} and @key{F2} are aliases for
@kbd{C-h} and @kbd{C-x 6}.) But this list is not cast in concrete; it
is just a matter of Emacs's standard key bindings. If you customize
Emacs, you can make new prefix keys, or eliminate these. @xref{Key