24 lines
1.5 KiB
Markdown
24 lines
1.5 KiB
Markdown
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---
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layout: post
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title: The Trouble with Time
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date: 2022-03-01
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---
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We are all bound by an oppressive force. One which declares what we must say and when we must say it. I am, of course,
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referring to tzdata.
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The Time Zone Database, or tzdata, is a list of time zones. Each entry includes information about UTC offsets, when
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daylight savings time begins and ends, and historical information about time changes. For example, if you ask tzdata about the zone
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`America/New_York`, referring to New York City, NY, USA, it will tell you that NYC was 4 hours, 56 minutes, and 2 seconds behind Greenwich
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until 18 November 1883, when it switched to 5 hours behind. It can also tell you when DST started and ended every year from 1920, when NYC
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introduced it, until now (and can predict when it may happen again in future years.
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If you're scheduling an event or even just showing a clock this information is essential. tzdata gives you this information
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for the entire world, with frequent updates when countries change their time zones and DST rules. That's why tzdata is used
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by billions of computers worldwide.
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Unfortunately, dealing with time is quite complicated. tzdata asserts that a time zone is an area where the time rules have been uniform
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since 1970. That zone will then be named by the largest city within the area.
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Continuing our NYC example, Washington DC's time has never differed from NYC since 1970 and it is smaller than NYC,
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so there's no `America/Washington_DC` and residents of DC will just use `America/New_York`
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