Translate Windows timezone to TZID?

Kevin Kenny kennykb at
Fri Jun 17 14:26:32 UTC 2005

The time zone names, offsets, and begin/end rules for summer time
are stored in the system registry, in the path

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

The keys under that path are the time zone names; within each key
are the values Display (the name to display in the Control Panel)
Std (the name to use for standard time), Dlt (the name to use for
summer time), Index (a number of the zone, but not terribly useful),
MapID (a map location of the zone, again not useful since that
functionality was removed from the Control Panel), and TZI.

The TZI value is an encoded version of a TIME_ZONE_INFORMATION

The two WCHAR arrays are removed, so there are

    - bias (minutes west) - 32 bits
    - standard bias (adjustment as of 0 January) - 32 bits
    - daylight bias (adjustment in Northern summer) - 32 bits
    - the fields of the two SYSTEMTIME structures, in order.

73 de ke9tv/2, Kevin KENNY   GE Corporate Research & Development
kennykb at           P. O. Box 8, Bldg. K-1, Rm. 5B36A
                             Schenectady, New York 12301-0008 USA

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