From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp11.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 aJc2Brq5xWPU2AAAbAwnHQ (envelope-from ) for ; Mon, 16 Jan 2023 21:55:22 +0100 Received: from aspmx1.migadu.com ([2001:41d0:2:4a6f::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp11.migadu.com with LMTPS id YCE8Brq5xWMjfQAA9RJhRA (envelope-from ) for ; Mon, 16 Jan 2023 21:55:22 +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 97EDC3980D for ; Mon, 16 Jan 2023 21:55:21 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pHWVI-0004Lq-Ur; Mon, 16 Jan 2023 15:54:52 -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 1pHWVH-0004Li-Q4 for emacs-orgmode@gnu.org; Mon, 16 Jan 2023 15:54:51 -0500 Received: from mailbackend.panix.com ([166.84.1.89]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pHWVF-0007Pm-Ms for emacs-orgmode@gnu.org; Mon, 16 Jan 2023 15:54:51 -0500 Received: from quad (panix2.panix.com [166.84.1.2]) by mailbackend.panix.com (Postfix) with ESMTPS id 4NwkmG6jDZz42Pc; Mon, 16 Jan 2023 15:54:38 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=panix.com; s=panix; t=1673902479; bh=3bKRs2YFxV/Xx0i/ua1sTSdoUDS7iIJQG2rwESHfmDA=; h=References:From:To:Cc:Subject:Date:Reply-To:In-reply-to; b=dDGwu3NsuefhkeT6bqFQO52Dn39uH8CjqCTgcTmoTFTBRU2Wue6PaMzd+XoZi3lk1 56BrQnvP63maNf+cSHVZwegxO98aTSUHosq6c/snge2uZNLumxmORP1F0ZsYAu+fg6 IXCpDmkYL1zDodd+LaUKllgK8yWHgvG8HTlMhM5Q= 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> <87cz7ejmgu.fsf@localhost> User-agent: mu4e 1.8.1; emacs 28.1 From: Robert Horn To: Ihor Radchenko Cc: rjhorn@alum.mit.edu, Daryl Manning , emacs-orgmode@gnu.org Subject: Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Date: Mon, 16 Jan 2023 15:47:23 -0500 In-reply-to: <87cz7ejmgu.fsf@localhost> Message-ID: MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=166.84.1.89; envelope-from=rjhorn@panix.com; helo=mailbackend.panix.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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: , Reply-To: rjhorn@alum.mit.edu 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=fail ("headers rsa verify failed") header.d=panix.com header.s=panix header.b=dDGwu3Ns; 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)" header.from=panix.com (policy=none) ARC-Seal: i=1; s=key1; d=yhetil.org; t=1673902521; a=rsa-sha256; cv=none; b=nMW327Spg+0HlWxTJv6P2MXReRqpIx5u9fhIJTarxbTd+IrM4LA0BuJg9gI15vaEJbjmJL l+ypupRlubhV7G54DaLukOSkKbJ1rS33+pJmF84EGX+EI7oEpWMA2foVypONHhxTM4aAxZ qac7y7hLgtTI200I/HtytjXB8wptmJlduJZV8kaqY7EdeoDLiMdG1Vuhb8iIucq8MjJdO9 uWpXCimPxMoH+Qj54ZLMAJSrzL+WTcKi0ejbfgf0Bxn5zg9/cj3jx8jI97nCj6M1Gw8gdP djenOeQlrqy3gBWJgoFT5wQ8KTC3lbSqhCJZ57lUqGyzAkVZ0KlcY2LOBiVVVw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1673902521; h=from:from:sender:sender:reply-to: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=XVLbkMYsyfX4FxGHDHhq+CgDL0tZBZM3nRrLZDvqZf8=; b=hkrCQlkyRLw9kruB4uVYa98kdRqZgh2vhJss8JgRGlle+ZxpzcjxpMQ8JagnC3kNivcVsf VY2OC88yZpbH/V20JQX9ErKS92RT6Ei1M9I/GpgZcp9ldOcLPn1HGw+P5u+L/jUd25DEyj WVEeJXSb2oRB8Z+1Cp2Yp5cyn6mE8ET/H9RyRV+K6xcvYxcxIwN0heWtFGLGPyXk146SWM E4P1Apssln8euC6G5xptR1itJwp2WlrdKVIozc9Ri78c+F8aU0gpSlRJa69BOVbd6jXvYO IRzT5olCGBwN2P0A7AAYzNfl4bYWOaS3aTTP7GGcFDapmkq8SGWCtSrWEDKgUw== X-Migadu-Queue-Id: 97EDC3980D X-Migadu-Scanner: scn0.migadu.com Authentication-Results: aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=panix.com header.s=panix header.b=dDGwu3Ns; 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)" header.from=panix.com (policy=none) X-Migadu-Spam-Score: -0.33 X-Spam-Score: -0.33 X-TUID: m/mBlSzi2NWY Ihor Radchenko writes: > Robert Horn writes: > >>> 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: >>> - DST transitions are not stable and change from year to year >>> according to strange rules that may involve Julian dates or >>> counting weekdays >>> - DST transition rules may change over time >>> - The new year day itself is not necessarily fixed (England >>> - Julian/Gregorian transitions happened at different times in >>> different countries >> >> Note that as a result "time when it happened" has different rules than >> "future time when it is scheduled". There are lots of other times that are >> scheduled as "future local time, subject to changing DST rules". This >> is particularly tricky for repeating times for regularly scheduled events. > > Not really. Countries may change DST at any moment in future. Or decide > to switch calendars (consider countries near the day transition line). > > And "past local time, according to the DST rules in effect at the time" > is also an option that might be useful in certain scenarios. > The issue is clarity of the expected rules for the format. If I schedule a meeting for 10:05 DST, but the rules change so that it is not DST at that location at that time in the future, what is the expected interpretation? It could be: a) the meeting should be at 10:05 ST, because the intent was to meet at 10AM in the then local time. b) the meeting should be at 11:05 ST, because the time was chosen to correspond to a particular sun angle. Getting the rules and explanation clear is the issue. It's a mistake that a great many people make with scheduling meetings. Those two behaviors need different encodings because they behave differently. -- Robert Horn rjhorn@alum.mit.edu