Super_R neu zuordnen, um zu steuern (Fedora 22)

Ich habe überprüft, ob der Schlüsselcode 134 (0x86) meine Super_R-Taste auf meiner Tastatur ist. Aber ich würde das gerne neu zuordnen, um es zu kontrollieren. Allerdings habe ich fast jede Permutation ausprobiert. Was mache ich falsch?

user@localhost ~ % xmodmap -pm
xmodmap:  up to 4 keys per modifier, (keycodes in parentheses):

shift       Shift_L (0x32),  Shift_R (0x3e)
lock        Caps_Lock (0x42)
control     Control_L (0x25),  Caps_Lock (0x42),  Control_R (0x69)
mod1        Alt_L (0x40),  Alt_R (0x6c),  Meta_L (0xcd)
mod2        Num_Lock (0x4d)
mod3      
mod4        Super_L (0x85),  Super_R (0x86),  Super_L (0xce),  Hyper_L (0xcf)
mod5        ISO_Level3_Shift (0x5c),  Mode_switch (0xcb)

user@localhost ~ % xmodmap -e "remove mod4 = Super_R"
X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  118 (X_SetModifierMapping)
  Value in failed request:  0x17
  Serial number of failed request:  11
  Current serial number in output stream:  11
user@localhost ~ % xmodmap -e "add control = Super_R"
X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  118 (X_SetModifierMapping)
  Value in failed request:  0x17
  Serial number of failed request:  11
  Current serial number in output stream:  11