An embeddable mapping between IANA Time Zone Database names
(like "America/New_York" and "China/Shanghai") and their equivalent POSIX "TZ" rule descriptions
(like "EST5EDT,M3.2.0,M11.1." and "CST-8").
In this way, more user-friendly names can be used in a timezone-setting API, and timezone rules can be easily updated with a firmware upgrade.
See example/example.c for an embedded use case.
Provide user-facing clients with zones.json to have a shared timezone vocabulary with the embedded library.
Since the build is heavily environment-dependant, the Dockerfile provides a consistent build environment — latest Arch Linux. When the IANA timezone database updates (a few times a year, usually: see the latest version here and compare to the release name/date), just run make in the root directory to rebuild all the "data" build artifacts (zones.c etc.). These data build artifacts can be checked in to source control since they change so infrequently.
If the IANA timezone database hasn't changed, you can just build zones.o, which isn't as sensitive to the build environment.