shift       Shift_L (0x32),  Shift_R (0x3e)
lock        Caps_Lock (0x42)
control     Control_L (0x25),  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)

! Part 1 (since about 2006)

! Avoid BadValue (TODO: debug why we get BadValue otherwise)
clear mod1
clear mod4

! Actually, my keyboard doesn't have 0xcc/0xcd keys, thank you...
keycode 0xcc = NoSymbol
keycode 0xcd = NoSymbol

! mod3 is Alt. I'm sure this is documented somewhere.
! It works that way in every program!
add mod3 = Alt_L
add mod3 = Alt_R

! In addition to Alt keys, my keyboard has ... drumroll ... *Windows* keys!
! These are meta keys, say, in Windows web browsers.
!   Don't take my word for it, hit F12 and type:
!   onkeydown = function(e){console.log(e);}
! And, um, Alt is already taken, so obviously Meta = Windows key.
! Is that not clear to someone, or is someone just being annoying
! with all this "Alt = Meta" garbage?
keycode 0x85 = Meta_L
keycode 0x86 = Meta_R

! No, mod1 is not Alt!
! In every program, mod1 is actually meta!
add mod1 = Meta_L
add mod1 = Meta_R
remove mod1 = Alt_L
remove mod1 = Alt_R



! Part 2 (since about 2015)
! What is going on?? USB thinks it can just wipe my xmodmap???
!
! 1. Locate xkb rulefile using
!
!   udevadm control --log-priority=info
!
!
! It will be something like
!
!    /lib/udev/rules.d/64-xorg-xkb.rules
!
!
! 2. Edit /lib/udev/rules.d/64-xorg-xkb.rules. Add:
!
!   RUN += "/big/usb_fix.sh"
!
! and do:
!
!   udevadm control --reload-rules
!
! note: using /big is intentional... on new Ubuntus, the system dies
! with "a start job is running..." in disk mounting. So we prevent this
! script from running ig /big is not mounted yet.
!
!
! 3. Create the /big/usb_fix.sh script:
!
! #!/bin/sh
! echo "xmodmap ~/.Xmodmap" >> /usr/local/usb_fix.log
!
! and make it executable.
!
!
! 4.
! mkfifo /usr/local/usb_fix.log
!
!
! 5.
! Create a script (e.g. named ~/bin/usb_fix_client)
!
! #!/bin/sh
! yes 'cat /usr/local/usb_fix.log | sh' | sh
!
! and put this in your .xinitrc.


! Part 3 (since about 2018)
!
! Every now and then, apt-get can overwrite the xorg-xkb-rules?
! solution for now is turn off automatic updates.