San Luis (Argentina) Time Zone Changes

by LATAM DST Taskforce

Background – San Luis Time Zone changes    

Argentina's San Luis province will officially observe a new time zone to adequate the time zone of the province with their geographic location. The new time zone information is the following:

• Daylight saving time starts: 0:00 of second Sunday of October the clocks should go forward to 1:00 of the same day. The time will follow the GMT-03:00.
• Daylight saving time ends: 24:00 of second Sunday of April the clocks should go back to 23:00 of the previous day. The time will follow the GMT-04:00.

Since the new time zone published by the government is different from any time zone defined in the previous years, Windows-based computers will not correctly interpret the time that is related to the transition to or from daylight saving time.

In addition to Microsoft products, other software, OS releases and hardware (phones, routers, switches and managed devices) may require updates and/or changes.

At this moment Microsoft is studying the feasibility of a hotfix to update the Windows Operating Systems with a new time zone definition for San Luis. Before release a hotfix Microsoft needs to follow test procedures to minimize the possibility of any adverse effect. We cannot guarantee that a hotfix will be released.

This document describes the supported workaround that needs to be followed prior to the change on Sunday April 11^th. Customers that follow this guide will need to change back to the proper time zone before the next DST period starts.

Before the next DST period starts we will publish advice and recommendations on the LATAM Team Blog at https://blogs.technet.com/latam.

General recommendations

• Please note that if you adjust the machine's clock manually, you may have adverse effects on your environment. This procedure is not supported by Microsoft.
• Before applying the changes on Windows Operating Systems to reflect the change in the time zone in San Luis, be aware of potential issues that will affect Microsoft Office Outlook and Exchange Server. Read "Impacts for Outlook clients and Exchange" section for more details.
• Contact Microsoft Support prior to any modification if you are unsure about the steps to follow in order to be prepared for the Daylight Saving Time change in San Luis.
• The most recent cumulative update to daylight saving time (DST) and world time zones (TZ) is now available for supported versions of the Windows Operating System via Microsoft Download Center and Windows Update. For more information about this cumulative DST and TZ update, visit the following Microsoft Web site: https://support.microsoft.com/kb/981128.
• This update does not include any update for the San Luis but it contains recent changes on several time zones around the world.

Impacts for Outlook clients and Exchange

There is a difference between the DST Dates and time zone established in previous years and the new definition adopted the San Luis government.  We are going to call this difference "Delta Period".

Depend of the time zone that the machine was configured to we can have a delta period at the end of the DST as follows:

The inconvenience experienced by Outlook client users happens for all appointments during the delta period that were created before the administrators update the DST dates on the operating system.

Those appointments will be off 1 hour. This may happen for both recurring and single-instance appointments.

The appointments created after the DST dates have been updated on the operating system will have the correct time.

Why do we experience this behavior?

To answer this question, we need to understand how Outlook schedule meetings and appointments:

Three factors affect the scheduling of a meeting and appointment in Outlook:

• The computer's clock setting (time).
• The computer's local time zone setting.
• The computer's daylight saving time adjustment setting.

Outlook time stamps the message request with the Greenwich Mean Time for the meeting. Outlook calculates Greenwich Mean Time by using the computer's clock time, plus or minus the local time zone adjustment, minus (depending upon the time of year) the daylight-saving time adjustment.

As soon as Outlook receives the meeting request it will calculate the meeting time for the recipient and schedule it on the calendar. If any of the three factors listed earlier are incorrect at that time, the meeting time will be incorrect. You cannot correct the time after the fact by correcting the factor in error; you must open the meeting request and manually correct the scheduled time.

How to update Windows Operating Systems and correct Outlook calendars    

Customer needs to follow the steps bellow to update the Operating Systems and Outlook calendar.

This section describes the anticipated impacts of the changes. We recommend customers to evaluate steps before apply on their environment.

Recently Paraguay changed their DST period to end on the Second Saturday of April at 23:59:59. Microsoft released a Time Zone cumulative update on March of 2010 that includes the new definition for GMT-04:00 Asuncion. The new date matches the date adopted by San Luis.

However, the start of the DST period for GMT-04:00 Asuncion is not the same as the date selected by San Luis. User and administrators will be required to take further actions before the next DST period starts in October of 2010. A fallback procedure will be published later on https://blogs.technet.com/latam.

Applies to:

• Windows XP, Windows 2003, Windows Vista, Windows 7, Windows Server 2008 and Windows Server 2008 R2 users
• The KB981128 does not apply to machines running Windows 2000.
• Windows 2000 users have to follow the KB 914387 (March 15, 2010 - Revision: 68.0) before continuing with the steps below.

Note:

• There is no automatic way of changing the time zone on Windows Vista and Windows 2008. This change has to be done manually.
• Administrators will not be able to correct calendar items in a centralized way (directly on the Exchange Server).

The following graph shows a summary of tasks associated with this change:

Below is a brief description of these activities:

If apply the KB981128 or KB914387 is a not possible user will have to wait until the DST fallback on April 11^th of 2010 and change the machines to a time zone with a definition of GMT-04:00 like GMT-04 Asuncion or GMT-04:00 Georgetown.

However, the start of the DST period for GMT-04:00 Asuncion is not the same as the date selected by San Luis. Users and administrators will be required to take further actions before the next DST period starts in October of 2010. A fallback procedure will be published later on https://blogs.technet.com/latam.

Applies to:

• Windows 2000, Windows XP, Windows 2003, Windows Vista, Windows 7, Windows Server 2008 and Windows Server 2008 R2 users

Note:

• There is no automatic way of changing the time zone on Windows Vista and Windows 2008. This change has to be done manually.
• Administrators will not be able to correct calendar items in a centralized way (directly on the Exchange Server).

The following graph shows a summary of tasks associated with this change:

Below is a brief description of these activities:

Changing Windows OS time zone to '(GMT -4:00) Asuncion'

Attention: To change the computer to GMT-04:00 Asuncion before April 11, 2010 is necessary to apply the KB981128 (KB914387 for Windows 2000 users). This KB updated the definition of the GMT-04:00 Asuncion. The new definition has the same DST end date as the one adopted by San Luis. Failure to do so will cause the machine to change time before the correct date.

In order to change the computer time zone to '(GMT -4:00) Asuncion', please follow the steps below:

For Windows Vista, Windows Server 2008, Windows 7 and Windows 2008 R2 machines:

1. Click Start and type: control timedate.cpl 

2. Click 'Change time zone…' button:
   

3. Select '(UTC-04:00) Asuncion' and click OK:
     

For Windows 2000, Windows XP and Windows Server 2003 machines: 

1. Click Start button, select 'Run' and type the following command:  control timedate.cpl

2. Click 'Time Zone' tab and select '(GMT-04:00) Asuncion':
   

    

Automatically changing machine time zone to '(GMT -4:00) Asuncion' on Active Directory environments

Warning: If your domain have multiples site in different countries make sure that you only deploy this solution to machines that are located in San Luis. We recommend customers to evaluate the alternative and test before apply on their production environment.

Note: this procedure is only supported in Windows 2000, Windows XP and Windows Server 2003, Windows 7 and Windows 2008 R2 Operating Systems. Users running Windows Vista and Windows Server 2008 will have to use the procedures specified in 'Changing Windows OS time zone to '(GMT -04:00) Asuncion'' section.

On Active Directory environments, administrators may want to automate the change of time zones to '(GMT-04:00) Asuncion'. This section explains how to deploy this time zone change via startup script. These procedures need to be executed in a Domain Controller or another machine with Admin Tools installed.

After performing all the steps below, all machines need to be restarted to automatically change the computer time zone. To avoid restarting a specific machine, please execute the procedures 'Changing Windows PC Operating Systems time zone' above to move this machine to '(GMT -04:00) Asuncion' time zone.

Use a script to change the machine time zone to (GMT -04:00) Asuncion

The script below can be used to change the current time zone to '(GMT -04:00) Asuncion' of the client computer. Then, the script writes an event to the Application log of the client computer where the script was run.

1. Click Start, click Run, type notepad, and then press ENTER.
2. Copy the following code, and then paste it into the Notepad document. . The following VBS Sample is only supported in Windows 2000, Windows XP and Windows 2003.

   On Error Resume Next strNewTimeZone = "Paraguay Standard Time" Set objSh = CreateObject("WScript.Shell") 'Get the StandardName key of the current time zone szStandardName = objSh.RegRead("HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\StandardName") 'Enumerate the subkeys in the time zone database Const HKEY_LOCAL_MACHINE = &H80000002 Set objReg = GetObject("winmgmts:{impersonationLevel=impersonate}!\\.\root\default:StdRegProv") szTzsKeyPath = "SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones" objReg.EnumKey HKEY_LOCAL_MACHINE, szTzsKeyPath, arrTzSubKeys 'Step through the time zones to find the matching Standard Name szCurrentTzKey = "<Unknown>" For Each subkey In arrTzSubKeys strTimeZoneStandarName = "" strTimeZoneStandarName = objSh.RegRead("HKLM\" & szTzsKeyPath & "\" & subkey & "\Std") If (strTimeZoneStandarName = szStandardName) Then 'Found matching StandardName, now store this time zone key name szCurrentTzKey = subkey End If Next Dim process, processid, result, strUpdateCommand Set process = GetObject("winmgmts:{impersonationLevel=impersonate}!\\.\root\cimv2:Win32_process") 'Add time change privilege to the process object process.Security_.Privileges.AddAsString "SeSystemTimePrivilege", True strUpdateCommand = "control.exe timedate.cpl,,/Z" & strNewTimeZone 'Launch control.exe to change time zone using the TZ key name stored in strNewTimeZone result = process.Create(strUpdateCommand, Null, Null, processid) If result <> 0 Then objSh.LogEvent 1, "Process to change machine time zone failed to execute on this computer. Unable to change machine time zone." wScript.Quit 0 End If 'Get the display name from previous time zone and compare with the new time zone szPrevDispName = objSh.RegRead("HKLM\" & szTzsKeyPath & "\" & szCurrentTzKey & "\Display") szNewDispName = objSh.RegRead("HKLM\" & szTzsKeyPath & "\" & strNewTimeZone & "\Display") 'Write entry to the Application event log stating that the update has executed If szPrevDispName = szNewDispName Then objSh.LogEvent 4, "Machine time zone was refreshed. The current time zone is: " & Chr(13) & Chr(10) & Chr(13) & Chr(10) & szNewDispName & "." Else objSh.LogEvent 4, "Machine time zone was changed from: " & Chr(13) & Chr(10) & Chr(13) & Chr(10) & szPrevDispName & Chr(13) & Chr(10) & Chr(13) & Chr(10) & "To: " & Chr(13) & Chr(10) & Chr(13) & Chr(10) & szNewDispName & "." End If

3. On the File menu, click Save As.
4. Select a destination, and then type "ChangeTZGMT4.vbs" in the File name box.
5. In the Save as type box, click All Files, and then click Save.
6. Double click in the ChangeTZGMT4.vbs to refresh time zone information.

Note: Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure. However, they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.

Deploying time zone changes using Group Policy

1. Click Start, click Run, type notepad, and then press ENTER.

2. Copy the following lines, and then paste it into the Notepad document.

   The script will test the Operating System version and apply the VBS described above on Windows 2000, Windows XP and Windows 2003. For Windows 7 and Windows 2008 R2 the script uses the utility TZUTIL to change the time zone. The script will ignore Windows Vista and Windows 2008.

   @echo off REM // Verify the Operating System Version. ver |find /i "6.">nul REM // If OS is Vista or newer skip to next session. IF %errorlevel% EQU 0 GOTO SIX REM // If OS is Windows 2000, Windows XP or Windows 2003 changes the run the ChangeTZ.vbs cscript \\contoso.com\NETLOGON\ChangeTZ.vbs GOTO End :SIX REM // Verify the Operating System Version. ver |find /i "6.0">nul REM // If OS is Vista or Windows 2008 ends script. IF %errorlevel% EQU 0 GOTO End REM // If OS is Windows 7 or Windows 2008 R2 changes the time zone with utility TZUTIL TZUTIL /s "Paraguay Standard Time" :End

   Note: You must replace the \\contoso.com notation above with the actual DNS domain name for your Active Directory domain.

3. On the File menu, click Save As.

4. Select a destination, and then type ChangeTZ_GMT4.cmd in the File name box.

5. In the Save as type box, click All Files, and then click Save.

6. Copy the following files to the Netlogon share folder of the domain controller that holds the PDC emulator role in the domain:

   ChangeTZGMT4.cmd
   ChangeTZGMT4.vbs

7. Wait until Active Directory replication occurs. Also, wait until the files and folders in the system volume (SYSVOL) shared folder replicate to domain controllers in the domain.

8. Click Start, click Run, type control admintools, and then click OK.

9. Double-click Active Directory Sites and Services.

10. Select a site where the computers in San Luis are located. (Small environments may have only a site named 'Default-First-Site-Name').

11. Right-click this site, and then click 'Properties'.

12. Click the Group Policy tab, click New, type DST Time Zone Change, and then press ENTER.

13. Click Edit. The Group Policy Object Editor tool starts.

14. Expand Computer Configuration, expand Windows Settings, and then click Scripts (Startup/Shutdown).

15. Double-click Startup, and then click Add.

16. In the Script Name box, type the universal naming convention (UNC) path of the ChangeTZGMT4.cmd file that is located in the Netlogon share. For example, type:

    \\contoso.com\NETLOGON\ChangeTZGMT4.cmd

17. Click OK two times.

Adjusting Outlook calendars for users in San Luis who moved to '(GMT -04:00) Asuncion'

As soon as you move to the time zone '(GMT -04:00) Asuncion", several Outlook calendar items starting from Sunday April 11^th 2010 will be displayed 1 hour off.

Options to correct your Outlook calendar in this scenario:

• Manually modify each appointment on the affected period (starting Sunday, April 11^th, 2010) after the operating system time zone has been changed. Instructions on the section "How to manually modify Outlook Calendar items"

  - or -

• Customers may also opt to use the "Outlook Time Zone Data Update Tool version 3.0" on the mode Permanent Time Zone Move to correct the Outlook calendar items. This procedure is explained below.

Special note:

We recommend you to print your calendar before any changes are made, and then review the calendar items to make sure these items appear at the correct times. You can use this printed copy of the calendar items to verify that Outlook has been updated successfully.

Step by step procedure to use "Outlook Time Zone Data Update Tool version 3.0" after a time zone move

The following describes the steps to be followed by end-users performing a time zone move:

1. The steps below can be followed for users who changed their time zone configuration to "(GMT -04:00) Asuncion".

2. Download and run the installation package from:

   https://www.microsoft.com/downloads/details.aspx?familyid=%20E343A233-B9C8-4652-9DD8-AE0F1AF62568&displaylang=en

3. Go to Start, All Programs, Microsoft Office Outlook Tools, Time Zone Data Update Tool and Select "Permanent Time Zone Move Mode".

4. Properly select the "Original Time Zone" drop down, and "(GMT -04:00) Asuncion" for the "New Time Zone:" drop down and click OK.
    

   NOTE: As with standard time zone updates, the tool defaults to updating affected items on your Calendar and in your Reminders folder.  If you would like to update additional items (e.g. items in additional Calendars or a PST), you can do so by clicking the 'Custom…' button and manually selecting the target folder

5. The tool will inspect your mailbox and will report how many appointments will be moved:
    
   If you click "Details" the appointment list will appear and you will be able to select all (default) or some of the appointments. In a normal situation you will move all the appointments to the new time zone. Click "OK" in the following dialog to proceed moving the appointments. A log file "Outlook Time Zone Update .log" will be generated in the %temp% directory.

6. Click "OK" to correct the calendar items listed.

7. After moving Click "OK" again to close the tool.

8. Review your calendar items from Sunday, April 11^th, 2010 and verify they were correctly updated.

How to manually modify Outlook Calendar items:

After you move from another time zone to '(GMT -04:00) Asuncion", your calendar items will be one hour off on the Delta Period starting from Sunday, April 11^th, 2010.

A simpler alternative to correct the Outlook Calendar items is by adjusting the appointments manually. To do so, please proceed as follows:

1. Start Outlook, and then open the Outlook calendar.
2. Manually move each meeting that you organized so that they occur at the correct time.
3. Send an update for each meeting that you moved to the meeting attendees. This action causes the calendar for each attendee to display the correct time for the meeting.
4. Manually move each single-instance appointment.
5. Manually move all recurring appointments that occur in the extended DST period.

Recommendations to minimize the impacts on Outlook/Exchange:

• Simulate the changes on a lab environment, so you know what will happen and what to expect.
• Work in conjunction with the operating system team to update the DST dates as soon as possible to minimize the chance of users creating new appointments during the delta period before the operating system DST dates get updated.
• Before doing any change on the DST information, request the users to print their schedule so they have a reference to follow in order to manually update the appointments later if needed.
• Take a full online backup of your Exchange Servers in case you decide to use the Exchange Calendar Update Tool.
• For the meetings with multiple attendees only the meeting requestor should update the time and send the update to the others.
• Include the time of the meeting in the e-mail request so that invitees can double check the correct meeting time (such as, "Project brainstorming - 11:00 A.M. San Luis time").
• Exercise caution with the appointments and meetings in the extended DST period. When in doubt, verify the correct time with the organizer.

References:

941018 How to address daylight saving time by using the Exchange Calendar Update Tool

931667 How to address time zone changes by using the Time Zone Data Update Tool for Microsoft Office Outlook

943390 Some Outlook calendar items are rebased incorrectly when you use the Outlook Time Zone Data Update Tool to adjust for daylight saving time changes in certain time zones