From 871948edfecb00bf06d5904ab3686aad34412aae Mon Sep 17 00:00:00 2001
From: Paul Eggert tz
databasetz
databasetz
databasetz
database
-If your government plans to change its time zone boundaries or
-daylight saving rules, inform tz@iana.org
well in
-advance, as this will coordinate updates to many cell phones,
-computers, and other devices around the world.
-The change should be officially announced at least a year before it affects
-how clocks operate; otherwise, there is a good chance that some
-clocks will operate incorrectly after the change, due
-to delays in propagating updates to software and data. The shorter
-the notice, the more likely clock problems will arise; see "On
-the Timing of Time Zone Changes" for examples.
-The tz
data can represent planned changes
-far into the future, and a long-planned change can easily be reverted
-or otherwise altered with a year's notice before the change would have
-affected clocks.
-
Changes to the tz
code and data are often
propagated to clients via operating system updates, so
client tz
data can often be corrected by
@@ -286,6 +270,49 @@ displays changes between recent tzdb
versions.
+If your government plans to change its time zone boundaries or
+daylight saving rules, please send email to tz@iana.org
well in advance,
+as this will coordinate updates to many cell phones,
+computers, and other devices around the world.
+In your email, please cite the legislation or regulation that specifies
+the change, so that it can be checked for details such as the exact times
+when clock transitions occur.
+It is OK if a rule change is planned to affect clocks
+far into the future, as a long-planned change can easily be reverted
+or otherwise altered with a year's notice before the change would have
+affected clocks.
+There is no fixed schedule for tzdb
releases.
+However, typically a release occurs every few months.
+Many downstream timezone data distributors wait for
+a tzdb
release before they produce an update
+to time zone behavior in consumer devices and software products.
+After a release, various parties must integrate, test,
+and roll out an update before end users see changes.
+These updates can be expensive, for both the quality
+assurance process and the overall cost of shipping and installing
+updates to each device's copy of tzdb
.
+Updates may be batched with other updates and may take substantial
+time to reach end users after a release.
+Older devices may no longer be supported and thus may never be updated,
+which means they will continue to use out-of-date rules.
+For these reasons any rule change should be promulgated at least a +year before it affects how clocks operate; otherwise, there is a good +chance that many clocks will operate incorrectly after the change, due +to delays in propagating updates to software and data. +The shorter the notice, the more likely clock problems will arise; see "On +the Timing of Time Zone Changes" for examples. +
+tz
database