/etc/xul-ext/calendar-timezones.js is in xul-ext-calendar-timezones 1.3+build1-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | // Place your preferences for xul-ext-calendar-timezones in this file.
// You can override here the preferences specified in
// /usr/share/xul-ext/calendar-timezones/defaults/preferences/preferences.js
|