How to determine whether the OS has the latest DST rules

Hello, I am working on an issue related to Brazil timezone. Our code reads the DST rules from windows registry instead of tzdata. My question is -- how do I determine whether the windows system has applied the latest timezone DST rules from the following registry? I don't know how to interpret the binary data HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones Any advice is appreciated. Thanks, Florence