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    It seems this may have something to do with summer Ramadan?

    Another such place is Morocco, where the schedule for the first start of DST and last end of DST are adequately defined, but every year since 2012 there has been a “DST suspension period”, such that DST ends before the start of Ramadan, and is restored sometime after. Not only does this mean that the clocks need to be changed four times in a single calendar year, but it also means that nobody is fully certain of when the middle two transitions will occur until the government makes an announcement. Part of the reason for this is that the dates for Ramadan are based on the observed sighting of the new moon. […] (By the way, Egypt used to do this as well, but only in 2010 and 2014.)


    Great article by the way, read the whole thing if you get the chance. Did you know Haiti this year cancelled DST with just 1 day’s notice?

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      I once worked on a system where somebody had, thinking they were a genius, added tracking of DST offsets to data collection and didn’t use UTC timestamps. They also failed to note where the data was collected. Oh, and all this was on Windows, because fuck you that’s why. This meant that changes to the timezone stuff (like in this case) are basically impossible.

      The eventual fix (which I pushed for over the course of months, because this person was really resistant to change and was scared of changing the code in the one customer site we had installed) was to track everything with UTC timestamps and track the civic timezone information separately (like, the nearest city for purposes of calculating offsets).

      The big annoying thing is that the common “local time” idea is an imperfect blend of location in space and in time, and that if you really do care what the DST and timezone stuff you need to explicitly store both the UTC (or TAI if you’re a special kind of snarfy) and the physical location of the point of collection. Otherwise, you’ll never really be able to reconstruct the local wall time at a later date.

      Time is surprisingly hard.

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        I used to get a little irritable in conversations (with persons lacking a technical background) when something about time or timezones came up. An important part of gradually becoming more level-headed (or at least numb?) about it was finding an approachable way to introduce people to the whole fustercluck, without wasting many liters of my own breath.

        Particularly, this little gem by Computerphile:


        I just make my disgruntled comment and say it’s not worth ranting about until they’ve seen that video. A lawyer once took me up on that and we ended up with a fantastic conversation about the ways in which human nuance screws up even the most well-intentioned parts of our respective fields.

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          For a bit more on this, be sure to read the other threads on the tz list for this month.