usr-share-X11-xkb-symbols

// Ctrl is mapped to the Alt keys, Alt to the Win keys, and Win to the Ctrl keys.
partial modifier_keys 
xkb_symbols "ctrl_alt_win" {
    key <LALT> { [ Control_L, Control_L  ] };
    modifier_map Control { <LALT> };

    key <PRSC> { type[Group1] = "ONE_LEVEL",
                 symbols[Group1] = [ Super_R ] };
};