From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp12.migadu.com ([2001:41d0:2:4a6f::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms5.migadu.com with LMTPS id 2IVMAIMn2mMmmAAAbAwnHQ (envelope-from ) for ; Wed, 01 Feb 2023 09:49:07 +0100 Received: from aspmx1.migadu.com ([2001:41d0:2:4a6f::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp12.migadu.com with LMTPS id IERVAIMn2mNeBQEAauVa8A (envelope-from ) for ; Wed, 01 Feb 2023 09:49:07 +0100 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id 8B13D16257 for ; Wed, 1 Feb 2023 09:49:06 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pN8ku-0008Rp-2E; Wed, 01 Feb 2023 03:46:12 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pN8kr-0008Rf-UG for emacs-orgmode@gnu.org; Wed, 01 Feb 2023 03:46:10 -0500 Received: from mout01.posteo.de ([185.67.36.65]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pN8kc-0003fX-Cu for emacs-orgmode@gnu.org; Wed, 01 Feb 2023 03:46:09 -0500 Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id DFE95240729 for ; Wed, 1 Feb 2023 09:45:39 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1675241139; bh=o73jbaTk9dR4vRN786JK5SWzOPuz5In3RLFHyChhq4w=; h=From:To:Cc:Subject:Date:From; b=GOpd4Ff92Dl/7joGkOZItc8plL00AR/UGTWSeTrCAD0y/epEmA5u4AY1I1W0AM8Qv L+5Ywcn1+UUBtloYa+9Rj1KkfFNqsHQ/iQbxk6QDhcZUeyCK/6VInVj8oKA4pCxt7f ObzsX5RzNb7yjrnwUPAX7HmK5lRtFxxRlmfeE377XifjpsjMim6j2cVOPJJC94vm5t AcKJOGlpQz9i3Wb//wO88fcMn9+7e7/8fGXZAD5/aDCtMohv9tJqfzkOvkZ/sRGFqh AT3x0bsc0BAs+h7ADZ7O9IjKqKoF03Fr2jUHtRkTvIuJ+UHzHUSAeBJngX0vsWxnis IlXO2OwoWoAuw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4P6Fqk0mt0z6tmF; Wed, 1 Feb 2023 09:45:37 +0100 (CET) From: Ihor Radchenko To: Tim Cross Cc: tomas@tuxteam.de, 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) In-Reply-To: <86wn51g661.fsf@gmail.com> 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> <86wn51g661.fsf@gmail.com> Date: Wed, 01 Feb 2023 08:46:14 +0000 Message-ID: <87357pn57t.fsf@localhost> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=185.67.36.65; envelope-from=yantar92@posteo.net; helo=mout01.posteo.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 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, RCVD_IN_DNSWL_MED=-2.3, 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=1675241346; 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=Lk0io54y7gKL9c1aklIv7hWnoQQpjUSGkSNuPSAN+SU=; b=WN23k3u6eiMlY40zHEXzphjdjWTwvchtJ5wZc6IKLPeZHRjT75coiszODUkDbXEMHCwl87 4SH4ZvQ/VjXwfaLQ+o70uavW/Dk9MOAjuqluP9P88PdVcGo2iTZZaKmnajpjUz+SeipXwD hl2n+6r6DdieSBlTMF7wmQLM0VavjGDYlUjc6obNYsrfEip9bf4Uz9ZnQVbF0jnyfI3P8v w90TbNkRhn8bPCbJLHpVO5e4m9MAT07H3nvM2kz3LTgWdfGRhGyq5urUOxpCJ2ngukjzsq EhjKTUI9vmQQRZ3jcLdiO0XeFemPyoJO078ckAqTnhXGqZ0VyPeZOoPUODyFJQ== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=posteo.net header.s=2017 header.b=GOpd4Ff9; 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=posteo.net ARC-Seal: i=1; s=key1; d=yhetil.org; t=1675241346; a=rsa-sha256; cv=none; b=uOcflezej5HwHafsz46SPCPQrPgI+e/1uZz75bb2jNHyQ2hArghxr2RmEnvTzkZNzKrGgx zdNdafwkg7WvwTe2OWvSUJcW4Xl6fne3h84kgvhpyWB3zg2PrMAcbqdgnM1ua+0ATBMOsg Y5m0KnY67TUsN6QHpa6Psnb8KuBGdKY7/d/sBlUgOmcr2fodT5YdZ8b0qF9EG+E4J+KQjV bdbo8R2WhyTDX6+lYdOcRprh4RBJRAqAZ8gAFyob7OvcT5KnJohCdKJzNLdpZ4o2BvxtwW qCL94OmmPLzdHTvzCFqU9hE0i0RoTGRxY9lYJ5ONdge4RirVGUC5T5aOrxjD2A== Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=posteo.net header.s=2017 header.b=GOpd4Ff9; 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=posteo.net X-Migadu-Scanner: scn0.migadu.com X-Spam-Score: -6.14 X-Migadu-Queue-Id: 8B13D16257 X-Migadu-Spam-Score: -6.14 X-TUID: MbGvb0uPKX9g Tim Cross writes: >> 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. >... > Personally, I cannot see the use case of including both a fully > qualitifed time zone (as in @Europe/Berlin) and an offset... Let me try to explain better. Just specifying time zone is ambiguous once per year during daylight transition. [2023-03-29 02:30 @Europe/Berlin] is special. According to https://www.timeanddate.com/time/zone/germany/berlin, 2023-03-29 is the time when the clock is shifted one hour back due to the daylight saving transition. The wall time goes like 2023-03-29 02:30 -> ... -> 02:59 -> (CEST -> CET) 02:00 -> ... -> 2:30 (again!) So, [2023-03-29 02:30 @Europe/Berlin] can mean two time points: before and after the transition. Specifying explicit offset is thus necessary in this specific scenario to disambiguate the timestamp: [2023-03-29 02:30+2 @Europe/Berlin] (before transition) [2023-03-29 02:30+1 @Europe/Berlin] (after transition) -- Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at . Support Org development at , or support my work at