From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp10.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms5.migadu.com with LMTPS id NkKUGS3P4mP2sgAAbAwnHQ (envelope-from ) for ; Tue, 07 Feb 2023 23:22:37 +0100 Received: from aspmx1.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp10.migadu.com with LMTPS id mAT2Fy3P4mMhxgAAG6o9tA (envelope-from ) for ; Tue, 07 Feb 2023 23:22:37 +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 2F0744511B for ; Tue, 7 Feb 2023 23:22:37 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pPWLi-0001RU-N3; Tue, 07 Feb 2023 17:22:02 -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 1pPWLe-0001Qx-QN for emacs-orgmode@gnu.org; Tue, 07 Feb 2023 17:22:01 -0500 Received: from stw1.rcdrun.com ([217.170.207.13]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pPWLd-0005mA-3w for emacs-orgmode@gnu.org; Tue, 07 Feb 2023 17:21:58 -0500 Received: from localhost ([::ffff:197.239.15.228]) (AUTH: PLAIN admin, TLS: TLS1.3,256bits,ECDHE_RSA_AES_256_GCM_SHA384) by stw1.rcdrun.com with ESMTPSA id 0000000000103955.0000000063E2CF08.00004A89; Tue, 07 Feb 2023 15:21:59 -0700 Date: Wed, 8 Feb 2023 00:46:45 +0300 From: Jean Louis To: Max Nikulin Cc: emacs-orgmode@gnu.org, ypuntot Subject: Re: [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Message-ID: Mail-Followup-To: Max Nikulin , emacs-orgmode@gnu.org, ypuntot References: <724af979-3825-4818-bc3b-76649752a004@gmail.com> <58ef4a47-8bda-2d85-05d4-e2c7e14d902d@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <58ef4a47-8bda-2d85-05d4-e2c7e14d902d@gmail.com> User-Agent: Mutt/2.2.9+54 (af2080d) (2022-11-21) Received-SPF: pass client-ip=217.170.207.13; envelope-from=bugs@gnu.support; helo=stw1.rcdrun.com X-Spam_score_int: 14 X-Spam_score: 1.4 X-Spam_bar: + X-Spam_report: (1.4 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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-Authentication-Results: i=1; aspmx1.migadu.com; dkim=none; 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=none ARC-Seal: i=1; s=key1; d=yhetil.org; t=1675808557; a=rsa-sha256; cv=none; b=CsGM/M9GUBYIvobPrU9EMRSnDNrBDnIKXu1CUYYpg6SVuU2SlJwn69w2+thK2PJie4LvKw mIcgfGtVXVxMAnBsnaxAP/ESvF8Gk3XB89B8pzvgc/HtCoMAJHgrcZpQ++wEMW7i77OpJS 82ONfZVT8p6aoQaxFIDEvKKAtXWFNMHnmZt+AcQiKm0CsNOdOkWR+aTu6vpZZARyncgNpU USWxkS+AlMiIWqqKucmmYTDKz+aHXjVVvze9VUn557QoCZE4tBY9ggbpOb3XFnoztaICjo b6DX3K3pimpNTGnZzwzGyaYYXibuyII3BiY+fjpGupu6FS7FMPfyAe29lfU9gA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1675808557; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=I0RfcmGr7hwBs6v5sj4HxgTAZP24qQhKETkB5Yw2zB8=; b=WA/V9LEIwxRsZyXij+m3Z3/M9WuQoSL2H0vRcBx61IcggHrQ4or3sAP+j40XmwCePYchIk k4X9JWj36s+L1IXGSS3g5IDx94qmZKVDhURjo4VHReK/boDs5wR3X4ST5Hfw9TmCY5+nZ0 lMNWApe1GMwHD2cBldHtKOEBeLxi8+VNhnnpJvcmjQ4JLbFXs5pJfClHqsW+VQZe+9LsQP SmrxckBqB32R5MPc81dLn0MMVbiJHrWlUS2dXFToDJxGdcTYcxt3nPAJlvrsqd60u0XQAV F9OZzsqaUTIgAV2hh2/SctW77tfWZmIDudnTh3slaOvp09KdkBdih5YG/74kdQ== X-Migadu-Queue-Id: 2F0744511B X-Migadu-Scanner: scn0.migadu.com Authentication-Results: aspmx1.migadu.com; dkim=none; 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=none X-Migadu-Spam-Score: 0.11 X-Spam-Score: 0.11 X-TUID: 4A8IACQwaXv8 * Max Nikulin [2023-02-05 20:06]: > On 05/02/2023 01:59, ypuntot wrote: > > Then, given the time zone and the local time, you can know UTC. > > If orgmode gets the UTC there is not ambiguity. > > Mapping from local time to UTC may be ambiguous, so mapping from local time > to time zone offset may be ambiguous as well. Okay, though explain practical case examples. Local time to UTC is almost always used in computing for accurate log purposes. Using UTC time for future events is vague, for reason that other human cannot know with certainty what the author intended to do. Maybe author intended meeting at 10 o'clock, but UTC offset in author's or participant's time zone changed, or even time zone entry is not any more. Author maybe had UTC offset -5, but now is -7, it becomes vague what time author really intended. Local time to time with UTC offset for same reason could be non-conclusive in future. Past is alright, as local time with UTC offset is pretty certain as time zones hardly change in past. Org needs first use examples, and then implementation for use examples. > Usual case is local time change due to daylight saving time. Notice that 2nd > and 4th lines in the results table have the same input, but time offset > differs by 1 hour in the output while local time is the same: Which is good example to demonstrate to people that 2:30 o'clock alone cannot be represented in such time zones without UTC offset. That "02:30" appears twice, it does not mean it is ambigous, as UTC offset or different name of time zone like CET, CEST, would indicat what time is that exacctly. -- Jean Take action in Free Software Foundation campaigns: https://www.fsf.org/campaigns In support of Richard M. Stallman https://stallmansupport.org/