This repository contains configuration files that were originally for the X Windowing System (a.k.a. X11 or Xorg). CrOS moved away from using X around 2015, but these files are still used to configure input devices. Thankfully this reduction in scope greatly reduces their effect on life satisfaction.
The syntax is now a subset of Xorg's configuration syntax, and using anything outside of that subset will either cause an error or just be ignored. Specifically, only InputClass sections are supported. Within those, the following entries are supported:
Identifier;Match directives (MatchProduct, MatchDevicePath, MatchUSBID, MatchIsPointer, MatchIsTouchpad, and MatchIsTouchscreen);Driver, which is ignored; andOption, which is used to specify gesture properties instead of X11 input device options (though some old X11 options may be hanging around).For more details, see the parsing code in Chromium's GesturePropertyProvider.