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Microsoft policy in response to Daylight Saving Time and Time Zone changes

Many applications and cloud services reference the underlying Windows operating system for Daylight Saving Time (DST) and Time Zone (TZ) information. In order to ensure that Windows has the latest and most accurate time data, Microsoft continuously monitors DST and TZ changes announced by governments around the world. Microsoft makes an effort to incorporate these changes to Windows, and publishes an update through Windows Update (WU). Each DST/TZ update released through WU will have the latest time data and will also supersede any previously issued DST/TZ update. KB article 914387 maintains the list of updates that have been released along with a short summary of the content that shipped with each update. Microsoft hopes that this will provide a consistent way for customers and partners to be informed whenever such an update is published.

Recommendations
In order for Microsoft to provide an update at the earliest and ensure a seamless transition to new DST and TZ policies, Microsoft recommends that governments provide the following:
  1. Ample advance notice (1 year or more) of the planned change.
  2. Official published confirmation of planned changes to DST or time zones.
  3. Concentrated efforts on promoting the change to affected citizens.
Microsoft DST/TZ Support Policy

Change typeChange detailsMicrosoft's Support PolicySolution
Change to a region's time zone rulesA subset of the region that shares a time zone makes a change to its DST requirements or changes the time bias of its time zone. A new time zone is required for the subset of users changing requirements because the existing time zone is needed as is for the rest of its users.

-or-

New DST or TZ change that does not match another TZ's exact parameters including historical time data accuracy (from 2010).

Microsoft will introduce a new time zone for such scenarios.

A new Windows time zone entry will be created only when a country/region (including dependencies), or a first-order administrative division of a country/region (state, province, department, etc.), has a separate and distinct history of UTC offsets and DST rules from existing time zone entries. Additionally, a smaller geographic area (county, city, etc.) qualifies for a new Windows time zone entry when its current UTC offset and DST rule combination is not provided by another Windows time zone entry.

If there is insufficient lead time to engineer, test and publish a Windows Update before these changes take effect, Microsoft will publish interim guidance on the DST Blog that can be used up until a Windows Update is made available.
Interim guidance and/or Windows Update
Changes to DST start/end datesModify an existing time zone by changing the DST rule or adding and removing DST to a time zone.

-or-

Modifying the time bias to an existing time zone.
Microsoft will publish a Windows Update that incorporates these DST changes to existing Windows time zones. In order to ensure these updates are made available before these laws take effect, we recommend governments provide ample notice (1 year or more) prior to the change taking effect.

If there is insufficient lead time to engineer, test and publish a Windows Update before these changes take effect, Microsoft will publish interim guidance on the DST Blog that can be used up until a Windows Update is made available.
Interim guidance and/or Windows Update 
Changes to display namesA region that has an existing Windows time zone announces changes to the name referenced in the Windows time zone display name.Microsoft will update the display name for the existing time zones for all supported languages and publish an update.

If there is insufficient lead time to engineer, test and publish a Windows Update before these changes take effect, Microsoft recommends using the existing time zone until a Windows Update is made available.
Windows Update


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आलेख ID: 22803 - पिछली समीक्षा: 17/08/2016 - संशोधन: 15

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