For the calculation of time zone boundaries, UTC offsets, and daylight saving times, MaiaMechanics.com uses the Time Zone Database (TZ) by IANA.
Jovian Archive's MMI for Windows was released in 2004, and has since relied upon the ACS Atlas by Alabe for time data. The ACS Atlas was the most reputable source of time data available at the time, and to this day is used by numerous astrological applications. And while ACS Atlas data is for the most part reliable, based on user feedback and our own investigations, it unfortunately does have its flaws. Most importantly, it is not maintained to a level of degree that provides us with enough confidence for the future.
TZ is an open source database which is constantly reviewed and updated. We are now confident that TZ data is 100% reliable for birth data calculation since 1970, while pre 1970’s data has only a 1% chance of a faulty result, which we will continue to monitor and refine. For this reason, TZ is the best solution moving forward. Furthermore, the public has the ability to report errors.
All Jovian Archive online chart calculators now use TZ as it represents the best solution moving forward. MMI continues to use the ACS Atlas but will soon receive an update to implement TZ.