FW: RE: How to determine whether the OS has the latest DST rules

Olson, Arthur David (NIH/NCI) [E] olsona at dc37a.nci.nih.gov
Thu Nov 6 20:27:06 UTC 2008

I'm forwarding this message from Phil Guera, who sent it by way of a
secure mail server.



I did some programming to read this information. Basically, the
information is given in the area that Microsoft calls TZI. It's a
complicated element to decipher, but if you give me the timezones you
are interested in, I can give you screen shots of the interpretation of
the registry binary data.

I wrote this TimeZonesExplorer just before Microsoft added some
historical capability to their registry's handling of timezones, and
never did update it to read the historical data, but the way MS stores
the info is based on the zone, current year, and subset of yearly
historical data. Though their treatment of historical data doesn't go
back in time very far like the TZ database does. I'm still running
Windows XP pro, but I believe the registry is structured the same on
Vista at this time. At any rate with the screen shots, you should be
able to see the basics of how to make the binary data more human
readable. It's just a matter of splitting the TZI info into parts and
performing some hex math conversion to get to the actual information
contained within it. 

Phil Guerra 

North Kansas City Hospital 
Information Technology 
Enterprise Technologies 
phillip.guerra at nkch.org 
Toll Free Relay Phone: 866-797-5805 
AOL IM: Mycroft2800

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