developersstandardsparser
How to Read a tzdb Zone and Rule Line: A Developer's Guide
A step-by-step breakdown of tzdb syntax: Zone definitions, Rule transitions, Link aliases, and AT/UNTIL modifiers.
Read ArticleArticles & Research
Deep dives into the history, anomalies, politics, and mechanics of the IANA Time Zone Database.
Browse Topics
dstpolicyhistory
The Countries That Abolished Daylight Saving Time, and Those That Brought It Back
Why governments repeatedly abandon and resurrect daylight saving time, and how tzdb rules track the political oscillation.
Read Article russiadstgeography
Russia's 11 Time Zones and a Decade of Temporal Reversals
From permanent daylight saving time to permanent standard time: how Russia reorganized its 11 time zones three times in four years.
Read Article historynetherlandsanomalies
The Curious History of Amsterdam Time: UTC+00:19:32.13
How the Netherlands maintained a fractional offset of 19 minutes and 32 seconds for three decades before World War II.
Read Article offsetsgeographystandards
The Fractional Offsets Still in Use Today: 15, 30, and 45 Minutes
Why several billion people do not observe whole-hour UTC offsets, from India and Iran to Nepal and Chatham Island.
Read Article anomaliessamoadate-line
The Nation That Skipped a Day: Samoa and the International Date Line
How Samoa moved from east to west of the International Date Line twice: repeating the 4th of July in 1892, then erasing December 30 in 2011.
Read Article historyrailroadsstandards
Watching Standard Time Spread Across the Globe: 1883 to Today
How local solar time gave way to coordinated standard time zones, driven by railroads, telegraph lines, and international diplomacy.
Read Article historystandardsarchitecture
What the tz database is and why one text file runs the world's clocks
How a public domain collection of plain text files maintained by volunteers coordinates timestamps for billions of devices.
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