[tz] FW: [Ext] The TZ Coordination

Zoid Soft zoidsoft at gmail.com
Sun May 31 18:22:23 UTC 2020

Astrologers have been significant contributors to this list.

> On May 31, 2020, at 1:25 PM, Matt Johnson-Pint <mj1856 at hotmail.com> wrote:
> Forgive me if this is in any way ignorant, but why must the DST transitions align so precisely with Ramadan?  Would it not be sufficient if the dates for the time change were predictable as long as the switch to GMT occurred sometime before the start of Ramadan and the switch back to GMT+1 occurred sometime after?  Is there a political, social, or religious reason why they must be so exactly aligned?
> -Matt
> From: tz <tz-bounces at iana.org> on behalf of Milamber <milamberspace at gmail.com>
> Sent: Sunday, May 31, 2020 7:03:50 AM
> To: Florian Weimer <fw at deneb.enyo.de>; Paul Eggert <eggert at cs.ucla.edu>
> Cc: Time zone mailing list <tz at iana.org>
> Subject: Re: [tz] FW: [Ext] The TZ Coordination
> On 5/31/20 12:09 PM, Florian Weimer wrote:
>> * Paul Eggert:
>>> On 5/30/20 7:00 AM, Florian Weimer wrote:
>>>>> Would this be a good opportunity to engage with the government of Morocco
>>>>> to encourage them to give more warning?
>>>> My understanding is that at present, they don't know themselves in
>>>> advance.
>>> Yes, I think you're right.
>>>> They would have to redefine the criteria to something based
>>>> exclusively on astronomical calculations
>>> That shouldn't be necessary, as they're using a conservative
>>> approximation; that is, it's OK if their approximation is a bit off
>>> because all they need to do is to bracket the actual Ramadan rather
>>> than predict its Gregorian dates exactly.  If they had an algorithm
>>> they could publish it and we could use it. And it would be
>>> technically feasible for them to have an algorithm; see the
>>> Morocco-prediction code in the tzdb 'africa' file for an example
>>> algorithm.
>> It looks like the algorithm predicted correctly the data of Eid
>> al-Fitr as 24 May, but the derivation of the end date from that is
>> suspicious.  I think it would make more sense if the time change does
>> not happen on Eid itself. 
> In Morocco (where I live), the end of Ramadan (arabic month) is follow by the Eid al-Fitr, and concretely it's 1 or 2 day off for the people (with traditional visiting of family, big lunches/diners, etc.). So for this year the astronomical calculations don't include the following 2 day off in the calc. This 2 days have fall in a Sunday/Monday, so it's not acceptable by people to have a time shift during these 2 day off.
> Perhaps, you can modify the (predict) rules for next years : if the end of Ramadan is a (probable) Friday or Saturday (and so the 2 day off is on a weekend), the next time shift will be the next weekend.
>>  A rule like this would ensure that Eid
>> still uses the same time as Ramadan in every year, which is likely
>> what people expect.

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