Grystmill Unofficial Time Zones Update
© 2007 Gary S. Terhune, MS-MVP
OVERVIEW: In late 2006, Microsoft released two
KB articles detailing Updates for Windows XP and Windows 2003
systems, made necessary by various changes to laws worldwide having
to do with which locales belong to which time zones, and Daylight
Saving Time start/stop dates. The Updates involved were posted to
Microsoft/Windows Updates in January, 2007 as "Optional" or
"Recommended" Updates. In February, 2007, a third "Cumulative"
Update was released, this time as a "High Priority" Update that is
installed by Automatic Updates to Windows XP and 2003 systems.
Please see the articles themselves to view the details of these
KB928388 -- "2007 time zone update for Microsoft Windows operating
KB929120 -- "Windows Server 2003-based computers and Windows XP-based computers that are set to the West Australia time zone do not change to daylight saving time on December 3, 2006"
KB931836 -- "February 2007 cumulative time zone update for Microsoft Windows operating systems"
Editions of Windows Vista already have
these changes incorporated into their initial releases, though I
believe the February Update is also be required for Vista systems.
However, no version of these updates has been provided for "legacy"
Windows systems, from Windows 95 through Windows 2000. Others have
provided "unofficial updates" to deal with this lack of Support, and
here is my own offering.
Granted, the only change(s) that a
person need truly be concerned with are those which relate to the
time zone (or zones) in which their computer is expected to operate.
They could choose, instead, to use TZEDIT.EXE, a utility available
for download from Microsoft's FTP site, to make these few and simple
changes. But, as with all things computer, using TZEDIT introduces a
greater risk of human error. For those willing to take that chance,
the utility can be downloaded here:
While this download is a copy of the
utility contained in the Windows 98 RESKIT, available on standard
Windows 98/98SE installation CDs, it actually works just fine for
all Windows 9x systems, but its use on Windows 2000 removes the
"STD" value and adds "Standard Time" to the sub-key name. I don't
know whether this would cause any problems or not.
DISCUSSION: The Time Zone
information contained in Windows Registries has two purposes:
1. The information is used by your
computer to relate your local time and date information to
Coordinated Universal Time (UTC), aka Greenwich Mean Time (GMT).
This allows computers in different time zones to all be "on the same
page" when it comes to time and date. For example, if I send an
email at exactly 1pm Pacific Standard Time (PST) on February 2,
2007, the following Date header is included: "Date: Fri, 2 Feb 2007
13:00:00 -0800". This translates to "2 Feb 2007 21:00:00 UTC"
(13:00:00 + 8 hours). If the recipient of this email is in Germany,
which on that date is UTC plus one hour, that person's computer
translates the date/time code to Feb 2, 2007 22:00:00, or 10pm,
which is when I actually sent the email in "real time". If that
email is also sent to another friend in Bangkok (UTC +0700), that
friend will see the email as sent on 3 Feb, 2007 04:00:00. Email is
just one simple example. With only a little imagination, one can see
that this worldwide time coordination of computers can be much more
critical in other applications where computers in different time
zones are sharing information. Of course, everyone could operate on
UTC, but that would cause problems with the human interface.
2. The Registry Time Zone information
also allows your Windows computer to automatically adjust your clock
and UTC offset for Daylight Saving Time.
Each sub-key of the Time Zones key has
a name that is important only to the internal working of Windows,
but which is representative of the information contained therein,
and includes the following Values:
"Display" -- What is shown as the
location and Standard Time UTC offset when you use the drop-down
menu in your Date and Time Properties dialogue, which is accessed
from the Control Panel or by double-clicking the clock in the System
"STD" and "DLT" values simply
repeat the name of the sub-key and add "Standard Time" or "Daylight
Time", accordingly. I can't see any specific function this data
serves, but I presume it is made available to applications that
might want to use it. (In the case of WinXP/2003, the "STD" value
simply repeats the sub-key name.)
"MapID", which allows the map in the
Date/Time dialogue, where present, to be centered upon the Time Zone
you choose. Cute but not of any real significance, and, in fact,
this data is missing for most if not all of the newest entries.
Probably just an oversight.
"TZI" -- A binary Value that includes
the UTC offsets for the time zone, and, most importantly for the
second item above, the dates and times at which the locale changes
from Standard Time to Daylight Saving Time and back. This is the
only truly important Value contained in these sub-keys in the case
of legacy systems.
Windows XP and 2003 systems, and
Windows Vista, also include another Value, "Index". I'm not clear on
what function this data serves, nor am I absolutely certain, at this
writing, whether it existed in those systems prior to the recent
UPDATES: The three new Updates for Windows XP
and 2003, in addition to updating the Time Zone information
discussed above, also install a new application/service that makes
future changes contemplated by variously enacted laws worldwide
automatic. For example, the recent changes in Australian law for the
Western Australia Time Zone only contemplate a three year "trial" of
the new change for 2007. Presumably, these Windows systems will
revert the data for that time zone to previous values, unless the
change is made permanent by Australia, at which time I presume that
another Update will make the proper adjustments. On a simpler scale,
for many of the changes that will only take effect in 2007 -- in the
United States, for instance -- the new Service just told Windows to
wait until 2007 to make the change. There are other more complicated
examples, but I'm not going to try to figure them out from the
Registry data. The entries for Israel, in particular, look very
interesting. The data for these changes are included in sub-keys of
the affected Time Zone sub-keys called "Dynamic DST". Other info has
also been added to the main Time Zone key that I'm not entirely
certain about, though the "Index" value seems to be involved.
The point is: None of the above is at
all applicable to versions of Windows earlier than XP/2003. So, for
the Unofficial Updates I am making available here, I have removed
all of that data. Also, the newer versions of Windows changed the
naming convention for the Time Zone sub-keys to add "Standard Time"
to all of them -- The key that used to be named "Afghanistan" is now
named "Afghanistan Standard Time". As far as I know, it's not
operationally important, and I could have left the new additions
named that way, or updated the old keys to the new naming
convention, but it simply makes no sense to me to name the keys
thusly, since a good part of the data involved also have to do with
Daylight Saving Time. So, on the off chance that it does make
a difference to the legacy systems, but more because of my own
sensibilities, I have renamed the new keys using the old convention,
removing "Standard Time" from the key names.
The "Unofficial Updates" I am providing here update
legacy Windows Registries to include all of the applicable new data
from the official Updates for Windows XP/2003. The "Legacy" systems
include all versions of Windows 95, 98 and ME, NT4 and 2000. I have
tested them on Windows 95B, 98, 98+SP1, 98SE, ME and 2000. Since the
Time Zones key in Windows NT Registries (Windows 2000 and NT4) are
sub-keys of "HKLM\Software\Microsoft\
Windows NT", and the 9x systems all have the Time Zones
key in "HKLM\Software\Microsoft Windows", they require different
update files. While the updates themselves are small in size, I have
packed them into self-executing ZIP files, both for maximum
portability and to evade many of the "security features" now in
place on Windows systems. The ZIP files contain a REG file that does
the actual updating, executed by a batch file that will also
automatically back up the existing Time Zones key to the Windows
directory before Merging the REG file. A Readme.txt file is also
included, and is automatically launched upon completion of the
I am only able to
provide this Unofficial Time Zone Update in the English language. As
far as I know, it is only useful to English Windows systems. I
invite Microsoft MVPs from other countries, and any other interested
parties, to use the data included in these files to create similar
Unofficial Updates for their own languages. You can also contact me
at firstname.lastname@example.org to
confer on methodology. I can't say, for certain, that the TZI data
translates to other languages, so you may have to recreate the files
appropriate EXE file using links below and run the EXE. (I suggest
saving this Update for possible future needs.) This latest version
of the update resets the Time/Date applet automatically, however
a full restart of the system is required in some cases.
A backup of the previous Time Zones Registry key, named
TZ_BAK.reg, will be saved to your Windows directory. If you
perform the procedure more than once, no further backups will be
SYSADMINS: See here for a discussion
of how best to update many systems.
WARNING! DO NOT use these
Unofficial Updates on any Windows systems other than the ones
listed. For Windows XP and 2003 systems, use Windows Updates.
NOTE! This update ENTIRELY
REPLACES the Time Zones key. Any custom modifications made prior to
installation will be LOST! However, there is an automatic backup
created before the changes are made, as discussed above.
"Grystmill Unofficial Time Zone Update" for Windows
(all versions of Windows 95, 98 and ME)
"Grystmill Unofficial Time Zone Update" for Windows
(all versions of Windows NT4 and 2000)
Updated May 8, 2007 to include new data for New Zealand