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 YJL6OmGe0mMS3wAAbAwnHQ (envelope-from ) for ; Thu, 26 Jan 2023 16:38:10 +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 0AnrOmGe0mM/JwAAauVa8A (envelope-from ) for ; Thu, 26 Jan 2023 16:38:09 +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 B4AD2A7FB for ; Thu, 26 Jan 2023 16:38:09 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pL4JR-00045o-Eg; Thu, 26 Jan 2023 10:37:17 -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 1pL4JQ-00045b-DY for emacs-orgmode@gnu.org; Thu, 26 Jan 2023 10:37:16 -0500 Received: from ciao.gmane.io ([116.202.254.214]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pL4JL-0005LA-4f for emacs-orgmode@gnu.org; Thu, 26 Jan 2023 10:37:16 -0500 Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1pL4JJ-0005c9-83 for emacs-orgmode@gnu.org; Thu, 26 Jan 2023 16:37:09 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: emacs-orgmode@gnu.org From: Max Nikulin Subject: Re: UTC or not UTC for timestamps in the past ([FEATURE REQUEST] Timezone support in org-mode) Date: Thu, 26 Jan 2023 22:37:03 +0700 Message-ID: References: <87lelxk87a.fsf@tsdye.online> <63ca5101.630a0220.b2298.3363@mx.google.com> <63cb2d0b.630a0220.f919a.6174@mx.google.com> <63cc5983.620a0220.a7d40.68f6@mx.google.com> <87r0vnhxj6.fsf@tsdye.online> <87ilgyiid8.fsf@tsdye.online> <87edrli4sr.fsf@tsdye.online> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Content-Language: en-US In-Reply-To: <87edrli4sr.fsf@tsdye.online> Received-SPF: pass client-ip=116.202.254.214; envelope-from=geo-emacs-orgmode@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: 16 X-Spam_score: 1.6 X-Spam_bar: + X-Spam_report: (1.6 / 5.0 requ) BAYES_00=-1.9, DKIM_ADSP_CUSTOM_MED=0.001, FORGED_GMAIL_RCVD=1, FORGED_MUA_MOZILLA=2.309, FREEMAIL_FORGED_FROMDOMAIN=0.141, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, NICE_REPLY_A=-1.15, NML_ADSP_CUSTOM_MED=0.9, SPF_HELO_NONE=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-Seal: i=1; s=key1; d=yhetil.org; t=1674747489; a=rsa-sha256; cv=none; b=h4/nxO+sJIh2o+C7ldPFVA8PobxuK9ljQQQkRHuvkuj1tB9q0+oSXhp8eipx38+rUJ5LBr 5ssT836ACbYM/ShY+68QBJwgir84nji23vOVyKWc4ZMNI1mXGY2A/Grje4TSGagy1rI0st mW9pUso2Gj6gxMg+XRCIN4MyfDhkeTK/brgp9FESFqRD2CEuDHuZJY6S+bQBi029ebl4k5 PJ3167qAQjtEaynD/1kACchxfPfuaW6FtJkdkEV0GxW3Nlyhs0Zj5TeD0je4yzw39kGJKW kCuVgLPWuYk3jb/5U2fBBWm5YTjmsxuiTifiFoieyHPNyo0p/Ix+BJBx+2FXRg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1674747489; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to: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=q476wI/c4qommI4TZRwHPCZKiIvcvAmVCxhqAaphVFg=; b=pB6MCEZmzjPiVKdDSrfFFpTNsF+2TZVmWxoVHfzTy3LtCe4WVfUH+5+bQXO1ueL9X/TZJK RC2/MublzzAEpOwd0PHb9MLgCueDY4lLR8hWp0qP4/wxGkDYGS9eZ0vyo/Ywomfsp1RaS9 VlIE2rheKS+iTp5F8rfmdo3q17vCLHcPiKNeImas4V7oti0UpQcAp5PhFfPNDncuCnLN0R SKnlYP1pW1VqiaU8oe4MdAA4xDSwzrjQyN/IlIffJGI0L3p8F0ZknW8OPDAp9s/uG/kdnz tSVlVGVluf7jHsY7f41jJpdAS24HZCxXcTxPx/wEUw0ylcRH4nTHhvBZjtVVkw== 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=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=gmail.com (policy=none) X-Migadu-Scanner: scn0.migadu.com X-Migadu-Spam-Score: 3.52 X-Spam-Score: 3.52 X-Migadu-Queue-Id: B4AD2A7FB 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=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=gmail.com (policy=none) X-TUID: akl85Qyx5WUk On 23/01/2023 23:04, Thomas S. Dye wrote: > * Kinds of event > - No-host event :: An event that takes place at an absolute time. > Participants must know their local timezone offset from UTC. Example > [2023-01-23 06:00@UTC]. > - Situated event :: An event that takes place at a time local to the > event site.  Participants must know their local timezone offset from UTC > and the event site timezone offset from UTC at the time of the event. > Example [2023-01-22 Sun 08:29@Australia/Sydney]. > - [Itinerant | Traveling | Mobile] event :: An event that takes place at > a time local to the event site, which might change after the event has > been scheduled.  Participants must know their local timezone offset from > UTC and the event site timezone offset from UTC at the time of the > event.  Examples might be a regular staff meeting that takes place at > 9:00 AM wherever the boss happens to be, or a proposal to meet with a > traveler when it is noon on Sunday for the traveler. Example [2023-01-23 > 06:00].  In this case timezone is set according to user timezone > preference in scope. Thomas, I mostly agree with the set of event kinds your suggested. Perhaps names should be justified to have precise and concise terms in UI. From my point of view their value is association with appropriate storage format for particular timestamp. An additional parameter (or sometimes first one to choose) is if explicit or implicit time zone should be used in the file. In the latter case the same kinds of events are possible, particular one is determined from a parent scope. User should be just aware what is actual time zone if it is implicit one. The following concept is aside from event kinds, but might (or might not) be useful to present agenda, to schedule events, to implement the feature. Perhaps a trip may be considered as an ad hoc timezone that follows offsets of time in locations to visit. (Several such ad hoc time zones may allow to track schedule of several people, but it may be too complex to use.) It may be considered close to "mobile" event, but the purpose is not to ensure correct time of particular event. It may facilitate presentation of timeline during the trip. Perhaps it is more correct to talk about how events are scheduled, not of event kinds. Consider Christmas and similar events. It is personal and local for each user. If you share your .org file (with specified file-local time zone) with other persons they celebrate accordingly to their local time. In addition they may decide that it should be pleasant for you to receive a greeting close to your local time. It seems during discussion we use terms in slightly different meaning, so I will try to clarify my point of view. I had a course on general relativity theory, so "absolute time" does make much sense for me. UTC is just a widely accepted agreement. I was bound to Earth rotation and accumulated some offset from more precise atomic clocks. UTC however currently is easiest way to perform time related calculations. My perception is still that UTC is one of timezones that may be used to specify event time. It is a bit special since it is used as a reference for other time zones, so it may be preferable for global events. If UTC considered as an ordinary time zone then the whole set of time zones may be divided into 2 classes: with fixed time offset (including UTC, Etc/GMT+3 that may be specified as -03:00, etc) and with time zones associated to specific locations. Second class is affected by DST, changes of offsets that may be source of uncertainty. The role of UI is to help user to choose a timezone that is suited best for particular event. For events in the future often it is necessary to use a location-based time zone, in other cases it is UTC or anyone with fixed offset. When you recording current time, explicit offset may be better. I am still unsure what is better to use: kinds of events or kinds of time zones. I agree that offset as a part of timestamp may be confusing, but I am afraid that significant part of affected users are unaware of UTC as well. That is why proper UI may be a challenging task. Thomas, for me event kinds are less important than understanding that UTC timestamps are not enough achieve properly working schedule. Currently you see that timezones associated with locations in some cases must be used in stored timestamps. Have you noticed that I missed anything significant in your messages?