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 CI0LAGClxWNYcgEAbAwnHQ (envelope-from ) for ; Mon, 16 Jan 2023 20:28:32 +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 GOt/O1+lxWMYpQAAauVa8A (envelope-from ) for ; Mon, 16 Jan 2023 20:28:31 +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 AA4012EBFA for ; Mon, 16 Jan 2023 20:28:31 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pHV98-0004fZ-4b; Mon, 16 Jan 2023 14:27:54 -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 1pHV96-0004fQ-QI for emacs-orgmode@gnu.org; Mon, 16 Jan 2023 14:27:52 -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 1pHV95-0000cc-81 for emacs-orgmode@gnu.org; Mon, 16 Jan 2023 14:27:52 -0500 Received: from quad (panix3.panix.com [166.84.1.3]) by mailbackend.panix.com (Postfix) with ESMTPS id 4Nwhr45trVz3xBD; Mon, 16 Jan 2023 14:27:48 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=panix.com; s=panix; t=1673897268; bh=5BLQzx+X8JQZFE1wPQ+u0N/2III08F15eWLhxMOw+OE=; h=References:From:To:Cc:Subject:Date:Reply-To:In-reply-to; b=R3Z1SHSVTL49W8IDn4Qe02yOmxOVoT/YN7aWmUYN8A3W9sa5iSatTQv275T8laZei WpztMIu0DjzVWO4UCYFhPhUReRLzQ8qK5VhfI2YQLZrkDTv9FWbjDszVP7XFxSxHyk XDPL7rT/10/CvGQZQ6yitnNOyvTpPIEqzj/FTghE= 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> User-agent: mu4e 1.8.1; emacs 28.1 From: Robert Horn To: Ihor Radchenko Cc: Daryl Manning , emacs-orgmode@gnu.org Subject: Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Date: Mon, 16 Jan 2023 14:22:35 -0500 In-reply-to: <87fscajo2q.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=R3Z1SHSV; 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=1673897311; a=rsa-sha256; cv=none; b=IsbBlJdQw79bMjyX38Q7QsVu2PFTxRgxe6B/S0sd41adJ6xuTQnfT/AZ6iXysC4I+Fon/9 2aojnWOHL0d1n3VVHbr2HO/F5h6l8ugbFw0RHxq3AsZvfsj89F9YWGDXp7zkyNc2Clv0Ft ossIsGwxrvIxUiLNUvFI61cQjf0PvLf+17fC696kSHJnRNvMTPDwsoPpJJHDmse+P1+FeD 7A4IwrrPIA4z6g0g2B4RXNsrCzUPGhD1u4fc0bQdQPFIByOJsemDGUweWduglwLAPdc2Va w/4+TkZpCJGbYHBLm41gxKbSWDl0N66xH5x8o8vDQMdPxlYhcnjBrANvm8q2vw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1673897311; 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=xCi01uzJEWCRDYKDsno/KB107dps4udBUZov9VVq+Zk=; b=IcwXu0pVdYVXDA82t8Q3Oh0iMfeKi1H94qvxNuz2sNtBvoZD/DuCCD37PHox3sLvclUwC8 RDKag6AC4jHNE0F8PQfxgiS/WvrITaWWAMpAQWniHYe11JAZYxSXdCULDIYm8lK6+lVkdf owplKGod3zzJlrowbBgVLbOBrmonYcdxmfOuRyp8WmNBJ/xXR5nAnQGFrb2kiqwgAouVTj unzN3HKs/HMHWXJxqnSuYA+ZyULbiiyq/EzmZSq+OyOzHLWZRFg8xJdtNe/LrwZoSS/7AY eOiesTDemCXZLcve0+10wlZ1oJcD8K732iowdQJctTz5Z6kfaXdS02QjNpPBbg== X-Migadu-Queue-Id: AA4012EBFA 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=R3Z1SHSV; 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: -0.83 X-Spam-Score: -0.83 X-TUID: us/FQW0GjDuK Ihor Radchenko writes: > https://www.youtube.com/watch?v=-5wpm-gesOY gives various examples. > To summarize: > > 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. > 5. Leap seconds! 23:59:59 -> 23:59:60 -> 00:00:00, according to > astronomical Earth observations > Fortunately, the most recent vote reached majority for eliminating leap seconds, hopefully within 8 years. -- Robert Horn rjhorn@alum.mit.edu