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 YKgFAfoGxGNMdgAAbAwnHQ (envelope-from ) for ; Sun, 15 Jan 2023 15:00:26 +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 WLm2APoGxGOTRwAAauVa8A (envelope-from ) for ; Sun, 15 Jan 2023 15:00:26 +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 B4850FCA2 for ; Sun, 15 Jan 2023 15:00:25 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pH3YS-0006RA-0Y; Sun, 15 Jan 2023 09:00:12 -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 1pH3YO-0006Qh-UT for emacs-orgmode@gnu.org; Sun, 15 Jan 2023 09:00:08 -0500 Received: from mout02.posteo.de ([185.67.36.66]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pH3YM-0005qE-C0 for emacs-orgmode@gnu.org; Sun, 15 Jan 2023 09:00:08 -0500 Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id 77BD7240104 for ; Sun, 15 Jan 2023 15:00:03 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1673791204; bh=FqEL+o123dMJwr966jR6XEAqr3HVRGfyVy8QxoEJBjQ=; h=From:To:Cc:Subject:Date:From; b=hmi3BB0fG9Q1pY7IBFLMP38WXiJ6TyQHOEwfNZB+0pxkHfy6X9AJYqPR+5Be5x7vE NztYJbV6C0glYz5QC4xK1Kw2RZbwNUMKnj9j8d8g7UnQoi863Dr6Nk82/Bc0pxyhil SsDiDbsFxnJiBDj5zG51uckfw72m88L42RnR2asvnqxvhAUEZ2Au3AcCTAsoi0er2x We46h52xki8M1MW1a1teX/ZCmvnAtg9d674tTmK0m133h/j9r+TJsCYlE//TaprA8/ 5HJh4PHq1wikmdCUKmn6wKH7r+WUIQScPYsgAW3I3pbcB3O2Jx+KeOTTZtZnsgB7Un 70+QtX5umVt9w== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4NvxcL3sQmz6tpT; Sun, 15 Jan 2023 15:00:02 +0100 (CET) From: Ihor Radchenko To: Max Nikulin Cc: emacs-orgmode@gnu.org Subject: Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda In-Reply-To: References: <63c287ca.a70a0220.4bd14.873b@mx.google.com> <63c2b760.170a0220.56455.a114@mx.google.com> <63c31663.a70a0220.3ab1f.a9e2@mx.google.com> Date: Sun, 15 Jan 2023 14:00:33 +0000 Message-ID: <87lem3ew3i.fsf@localhost> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=185.67.36.66; envelope-from=yantar92@posteo.net; helo=mout02.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, RCVD_IN_MSPIKE_H2=-0.001, 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=1673791225; a=rsa-sha256; cv=none; b=fGWWBVvksx9TZQEbA7FoU4O6IkAeg4t7h1aPCG5XoCcG0dTlObfUUQL7hZDgw2wHi8PicO Uo7WE6HnoEBT7U1F4sd2a7XxSN8SGybXwwUK0wwL6AY4xPRE7LYNog8EyJkVjg0QKVtguf CRcY4QUnw+ddpSISnM0w8/VLCp5yqj6+3/NaqauWxrhW6Ouy0HMeXaqjAJ1CSrm2n8OIn1 8eHkBV07tQd/m6kxoeaJWLcMBd2GfCPjNHcTEPyhG0NK7GbcslfGOJ4JzjZVTE6jmxvRYm Xi0UkqSTlTxlLdc6Z5xeCYs6kgZyxyrpjbzGgZArWmPYBIVpgyJhjiAWAcAkqg== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=posteo.net header.s=2017 header.b=hmi3BB0f; 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-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1673791225; 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=yvGlw8eHPGn8bSVYE3+JRB79OGVGEPbl7KdCLtjv6Xs=; b=K4dKMlK/GKMDj3y1gQInEWX/CDc+Tu7/8ryXxAFVfhwv91pck5sMvJL9tEdbB93QLuPqJe uMPqmv1jHzTSM/BTQKqImp5xIgJ5//UyWSJxAtXb9oCDS+dKrDNvM2qfnu7yunyRX9K2yi eemLn5hqt+8bFgSci06HUOk/gqduPashIanDdBKzlGfNIYvjqUlDzQIxaKI4H7VdxPlum8 /TGxKOmngqnpVzsskELyF2gLmW1LiEPuGcx7hVuHDy7PTBNO/EuQMpmfsiJmKhk44tOcVp Zhvfo14kkih4YxI/Om0/BU7X3elIArqL9OxltHaxkjrELiu4btzwYfFpT1VKRg== X-Migadu-Spam-Score: -4.56 X-Spam-Score: -4.56 X-Migadu-Queue-Id: B4850FCA2 X-Migadu-Scanner: scn1.migadu.com Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=posteo.net header.s=2017 header.b=hmi3BB0f; 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-TUID: A0yyXExXHz0s Max Nikulin writes: > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=54764#30 > Re: bug#54764: encode-time: make DST and TIMEZONE fields of the list > Thu, 14 Apr 2022 15:46:58 -0700 >> If you want to keep the TZDB identifier for advice about how to >> interpret dates relative to a timestamp, that's fine. But you should >> keep the UT offset in addition to the TZDB identifier, if you want your >> app to be fully accurate and useful. For example, you should store >> "1950-07-01 00:00:00 +0000 Europe/Lisbon" for a timestamp generated by >> TZDB release 2021a, so that when you interpret the timestamp in release >> 2021b you'll have an idea of what you're dealing with. > > So keeping redundant information may be crucial to get warnings that > some timestamps need to be reviewed. My takeaway from here is that automatically generated timestamps for past events should better contain redundant information: "1950-07-01 00:00:00 +0000 Europe/Lisbon" +0000 is what matters for time calculation while Europe/Lisbon indicates the actual timezone being implied. Then, if there is an event of TZ database change, Org might compare +0000 vs. Europe/Lisbon and display warning if there is discrepancy. For us, it means that we might potentially reserve <1950-07-01 00:00:00+0000@Europe/Lisbon> as a valid timestamp format. Warning is optional feature we might implement in future. -- Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at . Support Org development at , or support my work at