From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp12.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 yDYJL9TBxmPqUgEAbAwnHQ (envelope-from ) for ; Tue, 17 Jan 2023 16:42:12 +0100 Received: from aspmx1.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp12.migadu.com with LMTPS id CGnxLtTBxmPeuQAAauVa8A (envelope-from ) for ; Tue, 17 Jan 2023 16:42:12 +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 8F0B135813 for ; Tue, 17 Jan 2023 16:42:12 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pHo5P-0005WJ-R2; Tue, 17 Jan 2023 10:41:19 -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 1pHo5N-0005UZ-2P for emacs-orgmode@gnu.org; Tue, 17 Jan 2023 10:41:17 -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 1pHo5J-0006q8-2o for emacs-orgmode@gnu.org; Tue, 17 Jan 2023 10:41:15 -0500 Received: from localhost ([::ffff:102.85.233.9]) (AUTH: PLAIN admin, TLS: TLS1.3,256bits,ECDHE_RSA_AES_256_GCM_SHA384) by stw1.rcdrun.com with ESMTPSA id 00000000000561BB.0000000063C6C199.0000131F; Tue, 17 Jan 2023 08:41:13 -0700 Date: Tue, 17 Jan 2023 18:37:53 +0300 From: Jean Louis To: Ihor Radchenko Cc: Daryl Manning , emacs-orgmode@gnu.org Subject: Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Message-ID: Mail-Followup-To: Ihor Radchenko , Daryl Manning , emacs-orgmode@gnu.org References: <86zgamtv6o.fsf@gmail.com> <87tu0t1i0c.fsf@localhost> <63c2aa9e.170a0220.3bb49.9ef4@mx.google.com> <87pmbhz1x6.fsf@localhost> <87wn5mlo7f.fsf@localhost> <87pmbelnd0.fsf@localhost> <87fscajo2q.fsf@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <87fscajo2q.fsf@localhost> 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: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-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-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=1673970132; a=rsa-sha256; cv=none; b=Yx8Xg+Qzbdk0N/yd4k8+pjpdZrre1j0JRE8fqC1pUoZHGNYjfM5GDVd6EUgyTbiWQAZhrs pZ4SKICQVaqcfWRALCdg1SdvI6/QstFt8kP/br61lhQGjm+3qps9a00Axj7xUb4YWmOVs6 ZVTWSoyFaB8Mn+7d9eaS07uNwt0CUeyU0iMGfsi730MRwQvfN4FQ4/0SMGXkYbtX+qZkSO 5gr/n8z4tUgWkwg3I0yjoRn8C413K1v2EzNYh953DE1oTBwNro7GTrBhpfOG11jBtwEk4S ErIgGeS30tzm7TTUJoleou+BEKVTtpwyMnk1vpVoTiSQN3wA/uc3QSMJoYQzJg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1673970132; 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=IwC+t6ss+flz4pu68Ou49/Hxk+Cds7cZ+R9maIfh+pY=; b=UQs9v+fxyUWtQzfuxDawpQb+0IayrRNE5L13xdkftkcTSLvJWTKoJoZ6XMAWyji/bR4vHm t4+9Aw5X4LK3O0juKMg1FDJYPXVdxf88e6/WHmi/Jq0FvpZKUdsfJA8M1CDfyyRMMwl5XQ Y4PPZx/IilxYaOfLgEHXZWrZjvetzpcr0iSuhztGialWlbryV349e1biL5arGJj2E3FAgz oKdBmLe4lTqnu7c4Ft2aLewfmyTAl45mLlxIJsIFtlclh/zCN7KTk1bEXUkQFhll4/mPhA iQJ4IxTzeGG+4r98Z2Ts9/+na6qXMqNx393wk08G2glb6KHZmkMGs1A9e0oD/Q== 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: -2.43 X-Spam-Score: -2.43 X-Migadu-Queue-Id: 8F0B135813 X-Migadu-Scanner: scn1.migadu.com X-TUID: dGAdzU8eRAoz * Ihor Radchenko [2023-01-16 22:08]: > 1. Time (YYYY-MM-DD HH:MM) not continuous and may change arbitrarily at > certain times a year or in future or in the past: I am sure that system library must be responsible to know those changes. It is not for Org. So the calculation which transforms +1 time zone to -5 time zone shall be done by using system libraries which are supposed to have those options. I have no idea if they have. > 2. There might be arbitrary time gaps due to time transition, including > - One hour back during DST transition (northern and southern > hemispheres do the transitions in opposite directions) > - Multiple days skipped (Samoa skips a whole day during DST > transition) Interesting, but I still think that shall be in system library, and system libraries shall provide calculation functions. Does that exist in C library? > 3. We cannot assume that the same geographical area has fixed time zone > even at given point of time: > - Palestinian/Israeli people follow different time zones in the > contested territories They may, sure, I can also follow my own, but Org and system libraries shall use internationally accepted norms. > 4. Great Britain had new year on March 25 until 16th century > (March 24, 1000 -> (+1 day) March 25, 1001) Of course, that is why December is called by that way, as the tenth month, not twelfth. That may be part of representation of calendar, but because it is history, it is not so important for us in future. > 5. Leap seconds! 23:59:59 -> 23:59:60 -> 00:00:00, according to > astronomical Earth observations Should be part of C library to observe those things. -- Jean Take action in Free Software Foundation campaigns: https://www.fsf.org/campaigns In support of Richard M. Stallman https://stallmansupport.org/