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[124.169.47.98]) by smtp.gmail.com with ESMTPSA id l8-20020a170903120800b0019117164732sm11055028plh.213.2023.02.01.00.07.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Feb 2023 00:07:42 -0800 (PST) References: <87tu0mjb24.fsf@tsdye.online> <63ca1283.170a0220.5bc81.0fdd@mx.google.com> <87pmb9k8oi.fsf@tsdye.online> <3035CDD5-41DD-4516-9E4E-9E0DF16BE2E0@gmail.com> <87lelo8c9r.fsf@localhost> <2150768.1675077958@archlinux> <87tu063ox2.fsf@localhost> <87h6w63jgg.fsf@localhost> User-agent: mu4e 1.9.19; emacs 29.0.60 From: Tim Cross To: tomas@tuxteam.de Cc: emacs-orgmode@gnu.org Subject: Re: [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Date: Wed, 01 Feb 2023 18:52:31 +1100 In-reply-to: Message-ID: <86wn51g661.fsf@gmail.com> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=2607:f8b0:4864:20::62b; envelope-from=theophilusx@gmail.com; helo=mail-pl1-x62b.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-orgmode@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "General discussions about Org-mode." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-orgmode-bounces+larch=yhetil.org@gnu.org Sender: emacs-orgmode-bounces+larch=yhetil.org@gnu.org X-Migadu-Flow: FLOW_IN X-Migadu-Country: US ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1675238921; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references:list-id:list-help:list-unsubscribe: list-subscribe:list-post:dkim-signature; bh=kvgu9T3aqU8PBBXsxLrc/Rm0KqP+ui4H1okna9VUhvE=; b=syLQsrXEJsDg5P1q8RPie2tKcP6bm/XYwbk4gu/RaiL3YHzBsAxeXUOLIwtZ99x5evVhyT /y2RN1y/CGG9IUg3JQQ+gWBudrpCURLiKsQLkhQLnPGgI/sxz5X/KMl36nvsuYovpnS4y0 sp0t2xQK1xoHmuJNyxkWrq7cM9LQ2e03VMhMOw6c2QqWCu+xad/4bORpwikgX9JthS07Ex nJ556MhYgKvs2jY6DZgo+ECgG+hDq1ZXYAFaNiFfHBG3LPJ/DlqY5IAty06pMJakZvakNx tKECIH8Da6Tzh5+I1gZ3cMb7+LVVT35HWxmgCm5IQHxYFxsIyhvIFfqax9uQiA== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=FExowFMs; spf=pass (aspmx1.migadu.com: domain of "emacs-orgmode-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="emacs-orgmode-bounces+larch=yhetil.org@gnu.org"; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=key1; d=yhetil.org; t=1675238921; a=rsa-sha256; cv=none; b=eBR9YOOyLNPswsoSqhol+LyB5WA04sjb6MK0e/VSxHpGLJj4HSu/XUuCzeC5Y1FNTsUVGK OE1HJb73gvmgxj2XdtVYOO0OrtRc0OvTDoN31oFjDF+sF1dwZ7NtkzrzX0bOJ8CO+Q+gYm oZVcghBPhfQLoZ4kDrf1CX3UPN6xYBGUKuoNR98vgZocqiribRrMCQRRvB4Se4kKoe4hXG Q3VftPj5rVJVxoJpIvRytczCwGYRAxXumR9u6gKAxp7gO8zj8IxfT8BlSOwKSKR8qZ1bU4 s78aBief8t2KYiUFFdvHv0hj6cCfkdw+AjHuDkKlLr4U2vGTlddVMUISKpVB5A== Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=FExowFMs; spf=pass (aspmx1.migadu.com: domain of "emacs-orgmode-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="emacs-orgmode-bounces+larch=yhetil.org@gnu.org"; dmarc=pass (policy=none) header.from=gmail.com X-Migadu-Scanner: scn0.migadu.com X-Spam-Score: -6.56 X-Migadu-Queue-Id: C0C8C3596E X-Migadu-Spam-Score: -6.56 X-TUID: a4lJhAiPgrfl writes: > [[PGP Signed Part:Undecided]] > On Tue, Jan 31, 2023 at 11:12:00PM +0300, Jean Louis wrote: >> * Ihor Radchenko [2023-01-31 16:46]: >> > Specifying just @Europe/Berlin is ambiguous around the daylight savings >> > transition. >> >> Sorry, I cannot see practical example why is it ambiguous. Unless >> programmer does not take all information in account, it is not >> ambigous. People on this planet agree on time zones in advance, so >> there are few changes that people cannot plan in advance. > > (snipped the huge CC list) > > Either I understand you wrong, or you don't know what you are > talking about. 2023-03-23 02:30 @Europe/Berlin refers to /two/ > points in time, thus it /is/ ambiguous. If you use disambiguating > "time zones" (MEZ vs MESZ in this case) you can resolve that. > I think the confusion relates to context interpretation. If you see @Europe/Berlin in isolation, then it is ambiguous as it can refer to two different time zone definitions (standard v daylight savings). However, if you consider it in conjunction with a date and time, as in 2023-03-23 02:30 @Europe/Berlin, then it isn't ambiguous - in that case, it really just says 'Lookup the time zone offset in the databse for Berlin as of that date and time. Now that could change - for example, the German government might make a temporary or permanent change that would change the offset from UTC for that date+time the day after I look at it (or export it). Personally, I cannot see the use case of including both a fully qualitifed time zone (as in @Europe/Berlin) and an offset, but I also don't know all possible use cases - there could well be use cases where you want/need to record both the location time zone as well as the offset at the point when you recorded the timestamp. This is why I'm in favor of a flexible and extensible syntax and strongly disagree with any argument which says we don't need UTC or we don't need abbreviated TZ names or .....