tzdb 2021c: 0 time zone changes

Published: October 1, 2021 · Automatically generated from source data.

Published on Time Dozen: October 7, 2026

Briefly

Revert most 2021b changes to 'backward'.
Fix 'zic -b fat' bug in pre-1970 32-bit data.
Fix two Link line typos.
Distribute SECURITY file.
This release is intended as a bugfix release, to fix compatibility problems and typos reported since 2021b was released.

Other notes in this release (code, build procedure, documentation)

Revert almost all of 2021b's changes to the 'backward' file, by moving Link directives back to where they were in 2021a. Although 'zic' doesn't care which source file contains a Link directive, some downstream uses ran into trouble with the move. (Problem reported by Stephen Colebourne for Joda-Time.)
Fix typo that linked Atlantic/Jan_Mayen to the wrong location (problem reported by Chris Walton).
Fix 'backzone' typo that linked America/Virgin to the wrong location (problem reported by Michael Deckers).

Fix a bug in 'zic -b fat' that caused old timestamps to be mishandled in 32-bit-only readers (problem reported by Daniel Fischer).