Microsoft Policy in Response to DST/TZ Requests

Microsoft Windows has established an annual update schedule for daylight saving time (DST) and time zone (TZ) releases. Most Windows-based applications (and some services) reference the underlying operating system for DST/TZ information, but some applications and services do not. Hence many of our product teams also follow an annual product update cadence such a Windows, with provisions for semi-annual cumulative updates as needed. For each update release, Microsoft accepts change requests up to a few months (generally four to six) prior to the release date. The Windows Release schedule provides a regular cadence for other product groups to follow.

Following the Windows regular cadence for publishing newly legislated DST rules and TZ updates, cumulative DST and Time Zone updates are scheduled for release each December (to the Microsoft Download Centre and to Windows Update respectively) for the coming calendar year as long as there are time zones affected. When needed, Microsoft product groups may also provide a semi-annual update in the August/September timeframe. The product group will also publish the new or modified TimeZoneInformation (TZI) keys in an update to Microsoft KB article 914387 for IT professionals and systems administrators who may need that information. Microsoft hopes that this will provide a more predictable way for customers to anticipate and plan for our scheduled product updates as they are published.

Recommendations

In order to achieve more seamless transitions to new DST and time zones policies, Microsoft requests 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 the affected citizens.

Customer requests and the Microsoft DST/TZ Support Policy

Change Type	Change Details	Solution Recommendations	Solution
Change to a regions TZ rules	New DST or TZ change matches another TZs exact parameters.	There will be no product updates for this type of request. The recommendation is for the country or region requesting this change to use the existing time zone that matches the same parameters	Guidance
Changes to existing time zones	Modifying the DST start and end times and dates of a time zone (or several time zones that affect a particular country or region) with no time zone that matches the exact parameters. -or- Modify an existing time zone by change the DST rule or adding and removing DST to a time zone. -or- Modifying the time bias to an existing time zone.	In this scenario, if there is no existing time zone that matches the exact requirements of the country or region, the recommendation is to schedule the request to be included in the next DST/TZ cadence release. Microsoft’s ability to meet any country or region’s needs with this official DST/TZ policy, depends greatly on the regions providing sufficient time (6 months or more) of notification prior to the change taking effect.	Cadence Update -and- Guidance
New Time Zones	A 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.	This scenario requires a new time zone. The recommendation is to schedule the request to be included in the next DST/TZ cadence release. Microsoft’s ability to meet any country or region’s needs with this official DST/TZ policy , depends greatly on the regions providing sufficient time (6 months or more) of notification prior to the change taking effect.	Cadence Update -and- Guidance

On occasion, when there are extreme circumstances that require a change to a time zone, Microsoft may make an effort to provide a solution to the customers in the impacted regions through an Out-of-Band (OOB) Release. Any such package would include a Windows hot fix and a documented Outlook solution through the TZMOVE tool. Where a temporary workaround for customers exists Microsoft may recommend using the workaround until the Cadence Release is made available.