pressing an unmodified #\a:

KeyPress event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625668427, (527,-433), root:(577,365),
    state 0x0, keycode 38 (keysym 0x61, a), same_screen YES,
    XLookupString gives 1 bytes: (61) "a"
    XmbLookupString gives 1 bytes: (61) "a"
    XFilterEvent returns: False

KeyRelease event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625668474, (527,-433), root:(577,365),
    state 0x0, keycode 38 (keysym 0x61, a), same_screen YES,
    XLookupString gives 1 bytes: (61) "a"
    XFilterEvent returns: False

pressing a Control_L #\a:

KeyPress event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625738441, (166,-14), root:(216,784),
    state 0x0, keycode 37 (keysym 0xffe3, Control_L), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

KeyPress event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625738512, (166,-14), root:(216,784),
    state 0x4, keycode 38 (keysym 0x61, a), same_screen YES,
    XLookupString gives 1 bytes: (01) ""
    XmbLookupString gives 1 bytes: (01) ""
    XFilterEvent returns: False

KeyRelease event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625738744, (166,-14), root:(216,784),
    state 0x4, keycode 38 (keysym 0x61, a), same_screen YES,
    XLookupString gives 1 bytes: (01) ""
    XFilterEvent returns: False

KeyRelease event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625738902, (166,-14), root:(216,784),
    state 0x4, keycode 37 (keysym 0xffe3, Control_L), same_screen YES,
    XLookupString gives 0 bytes: 
    XFilterEvent returns: False


pressing a (presumed Super) #\a:

KeyPress event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625769488, (179,-14), root:(229,784),
    state 0x0, keycode 233 (keysym 0xffec, Super_R), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

KeyRelease event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625769488, (179,-14), root:(229,784),
    state 0x40, keycode 233 (keysym 0xffec, Super_R), same_screen YES,
    XLookupString gives 0 bytes: 
    XFilterEvent returns: False

KeyPress event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625769576, (179,-14), root:(229,784),
    state 0x0, keycode 38 (keysym 0x61, a), same_screen YES,
    XLookupString gives 1 bytes: (61) "a"
    XmbLookupString gives 1 bytes: (61) "a"
    XFilterEvent returns: False

KeyRelease event, serial 29, synthetic NO, window 0x3800001,
    root 0x4d, subw 0x0, time 625769648, (179,-14), root:(229,784),
    state 0x0, keycode 38 (keysym 0x61, a), same_screen YES,
    XLookupString gives 1 bytes: (61) "a"
    XFilterEvent returns: False