XKB useModMapMods, remapping Ctrl+Esc to Win and xmonad

Contents:
1. What useModMapMods in XKB interpretations means exactly?
2. Map Ctrl+Esc to Win key (Mod4) using XKB.
3. Using Ctrl+Esc as xmonad modMask.

X11 authentication and remote X clients

There is several methods of display access control, but the most used are two:
Host Access controlled by `xhost` and MIT-MAGIC-COOKIE-1 controlled by
`xauth`. Below is just what you can find in man, and may be a little more.