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 sIvRAYMK4WPdggAAbAwnHQ (envelope-from ) for ; Mon, 06 Feb 2023 15:11:15 +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 kNm3AYMK4WNcpgAAauVa8A (envelope-from ) for ; Mon, 06 Feb 2023 15:11:15 +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 84BB4D74E for ; Mon, 6 Feb 2023 15:11:14 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pP2CZ-00060l-Dr; Mon, 06 Feb 2023 09:10:35 -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 1pP2CX-0005zU-J0 for emacs-orgmode@gnu.org; Mon, 06 Feb 2023 09:10:33 -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 1pP2CU-0002XH-2S for emacs-orgmode@gnu.org; Mon, 06 Feb 2023 09:10:32 -0500 Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id 40772240276 for ; Mon, 6 Feb 2023 15:10:25 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1675692625; bh=a+Eqst+ZZUex3+y48k590qm91qAdQnt7ozdEQ8nJL0A=; h=From:To:Cc:Subject:Date:From; b=dSJDvoZ+zR5mLzP4d5HsfD2jtC0vP2OuZzxd40YU4E110u+UbA2AMBwh4ssnpnVIM SjImH9rZw9cGkeF/nS3az+UUYxqe4/yEbzggZ6VgWPpZKERFABBwlWi/ck0pSZvluc bEAVuScBLl+nyhbFwIyMtpGsSdzXFtHXcB/xTsJjsf8noa6+Kw35TP/T2+Flf51Msa N4Vr9tptPq8q3tVtUac1d8xyGTcOd592yz29Q0CDnIfJiUiEjsVGgLhmwS7lS4VwQE acctx5ScMxIdm2B7vEx/D2XUMWlCyKcClbGO7EI9HQNq3uEe3CZi8OgDD4nKiPi2hM XOdFqVLc+RzIw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4P9Sp45Kylz6tnw; Mon, 6 Feb 2023 15:10:20 +0100 (CET) From: Ihor Radchenko To: Jean Louis Cc: Ypo , Org-mode 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: References: <87lelce6iu.fsf@localhost> Date: Mon, 06 Feb 2023 14:10:58 +0000 Message-ID: <87357i9959.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-Country: US X-Migadu-Flow: FLOW_IN ARC-Seal: i=1; s=key1; d=yhetil.org; t=1675692674; a=rsa-sha256; cv=none; b=tdlxc5WIMfVXPeTvYpTkgIr6byMrTtFYNC4F7YAkRuQAfVLqleBy4utEwD8Zt8VvA+GzOo bbQCqKBMgRiV+nUiXMLhZO/J9ahQK7Szl2Vh2nG/UMgCWPYjBPd0DW4YM+WFiWZvf+cloM 0UnJM1dFZHHmlcKMyOj42yxBnJU1k7xkERq3wUNrwyzRQPZMe/MEIzdNFn7P7rxOu9rr/0 WW1Ufg9o5xY8hQXxaL2LQcqWs98ywO/7GBmJwN0E++zC6xytYv6fwodqSukciq7oafrV/U HvcwZ5cFlL5dLm+itZ+FUGkGhFDxeHs3LfYrfFHF1QiitBBuo8x+BykRKdvy0g== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=posteo.net header.s=2017 header.b=dSJDvoZ+; dmarc=pass (policy=none) header.from=posteo.net; 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" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1675692674; 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=A/NZU32abxN5ABjSWc6lqasQpCWad9Q3ivkG7o38YJA=; b=U7+nFSjWXGw+B+/S10Mlr/X2uk4x8dWgeS7UYXEVELdXAHYFZn3boD4rXGLgBxqy3S5lY2 KVO1sd3IGcu3VlJZblccTyleVOIAjSns+OyIYiyABr+NOwLP2uc5vOE15Ajv1vV6ASEeMi gt5gUievelgqq8Fu3pJ9H5+ofAV73EKgkAHk22bH2sFoKi+U+FsDeznNErY7IT6rlWljNK UnsMvy3k6vF3FN9UYSCyZGYiHdQeLPrQj22esByKEsEL1416eJEjXRR2uWHc94UhTkM0VK WwYk/LV80Jy0cv/jLm+sWgVhSmGACSgOWIk0FZq2WEwz91FRtji+Hb2SSSs5WA== Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=posteo.net header.s=2017 header.b=dSJDvoZ+; dmarc=pass (policy=none) header.from=posteo.net; 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" X-Migadu-Scanner: scn1.migadu.com X-Migadu-Spam-Score: -4.55 X-Spam-Score: -4.55 X-Migadu-Queue-Id: 84BB4D74E X-TUID: iUrWy+Xo0iCy Jean Louis writes: > * Ihor Radchenko [2023-02-05 13:45]: >> [2024-02-04 12:00 @-08,America/Vancouver] will use fixed -8 offset > > What does that mean practically? Provide example for better > understanding. It means "when I scheduled this item, I expected the UTC offset at the time of the timestamp to be -08 and remain so. It was motivated by America/Vancouver time zone, but if it changes in future, I do not care - the scheduled time should remain at specific time point relative to UTC". > - The UTC offset is not certain to remain fixed in the future. Yes. But fixing UTC offset means that time point is fixed. Example: you need a timestamp exactly N hours from now. It must not be affected by time zone rule changes. > - If you do not have the time of creation of the timestamp above, you > cannot know with certainty what was the offset in past, to calculate > new UTC offset in case it changed America/Vancouver in the above timestamp is nothing but a reference comment. One may or may not use it. > - As not even time zone is certain to remain in existence in future, > you will need to use time zone, in order to derive that future UTC > offset correctly. As it could change in mean time. If timestamp must follow the future time zone rules, can just use [2024-02-04 12:00 @America/Vancouver] >> [2024-02-04 12:00 @America/Vancouver] will use @America/Vancouver time >> zone, as it is be defined in you OS time zone database. > > If you do not keep UTC offset, you will miss changes in future and > generate errors. Only if you care. Maybe it is not an error to follow the future changes. If you want to be notified, just use [2024-02-04 12:00 @-08,!America/Vancouver] explicitly stating the offset you expect in future. >> [2024-02-04 12:00 @-08,!America/Vancouver] (note "!") will use fixed -8 >> offset, but also calculate America/Vancouver time from TZ database, >> compare it with the time coming from -8 offset, and warn you if there is >> inconsistency. > > The UTC offset is the log what was the UTC offset at the time point > when timestamp was created, as future UTC offset cannot be known. Sure. -08 is expected offset. > Making it "fixed" does not fix it in real time, you are then > introducing something new than what other programs do with time. I do not understand this statement. > I do not think that you need "!", you are creating work not necessary > for users. I hope that I clarified the need in the above examples. You may also refer to the reference in the original proposal. The idea with "!" is explained in more details. > If users wish to get some warnings, let them customize single option. This will be less fine-grained approach. For some timestamps, you don't need warnings. Of course, default customization may be also provided to enable warnings for timestamps without "!". -- Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at . Support Org development at , or support my work at