https://en.wikipedia.org/wiki/Space-cadet_keyboard https://en.wikipedia.org/wiki/Space-cadet_keyboard Also, if you have a 104/105 key keyboard with "windows" a

https://en.wikipedia.org/wiki/Space-cadet_keyboard https://en.wikipedia.org/wiki/Space-cadet_keyboard Also, if you have a 104/105 key keyboard with "windows" and "menu" keys, you do& have a keyboard with four modifier keys. From my .Xmodmap file: clear Mod1 clear Mod3 clear Mod4 clear Mod5 ! left alt -> Meta keycode 64 = Meta_L add Mod1 = Meta_L ! right alt -> Alt keycode 108 = Alt_R add Mod4 = Alt_R ! left windows -> Super keycode 133 = Super_L add Mod3 = Super_L ! right windows -> Hyper keycode 134 = Hyper_R add Mod5 = Hyper_R Emacs uses all four automatically, as M- A- s- H- respectively. (alternatively, see: http://ergoemacs.org/emacs/emacs_hyper_super_keys.html http://ergoemacs.org/emacs/emacs_hyper_super_keys.html )