$ xev
KeyRelease event, serial 25, synthetic NO, window 0xe00001,
    root 0x3a, subw 0x0, time 13397776, (398,81), root:(1360,394),
    state 0x0, keycode 115 (keysym 0xffeb, Super_L), same_screen YES,
    XLookupString gives 0 characters:  ""

##</code><code>##

!~/.Xmodmap will execute when X starts.
keycode 115 = F40
! run xmodmap ~/.Xmodmap to reassign the key without restarting X