The Microsoft Windows time zone database changes periodically, and Microsoft pushes out changes via Windows Updates. These changes are also announced on the Microsoft Daylight Saving Time & Time Zone Blog, and in the Daylight Saving Time Help and Support Center.

When a change is made, in addition to the data being changed, there is a version number that is updated in the registry at the following key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones

The version is in a REG_DWORD value called TzVersion. On my computer, it is currently set to the value 0x7dd0100 (131924224 decimal).

The question is: Where can I find a list of changes by version number? While each of the updates increments the version number, they are not monotonic, and the blog that references the updates does not make note of the version number.

Surely there is a table somewhere that includes the version number, release date, and corresponding MSKB number. I just can't seem to find it. Anyone know where (or if) it is published?

  • I would find it highly unusal for Microsoft to publish these changes. The MSKB is already documented and and daatabase exists for those. specific changes based on the number of time zones would is unlikely to exist. – Ramhound Aug 21 '13 at 18:27
  • @Ramhound - What I'm after is a way to know which changes have or haven't been applied. Since all I can see is the version number - that makes it difficult to work backwards through a change history that doesn't reference version numbers. – Matt Johnson Aug 21 '13 at 18:57
  • It's very likely every patch has the current information for all time zones. – Ramhound Aug 21 '13 at 19:26

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