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 cC0HGmhp2mNKJAAAbAwnHQ (envelope-from ) for ; Wed, 01 Feb 2023 14:30:16 +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 8CbUGWhp2mMKPQAAauVa8A (envelope-from ) for ; Wed, 01 Feb 2023 14:30:16 +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 141DD869B for ; Wed, 1 Feb 2023 14:30:16 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pND8C-0001ZE-Db; Wed, 01 Feb 2023 08:26:32 -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 1pND7p-00018Y-Iq for emacs-orgmode@gnu.org; Wed, 01 Feb 2023 08:26:13 -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 1pND7k-0005Be-Ft for emacs-orgmode@gnu.org; Wed, 01 Feb 2023 08:26:08 -0500 Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id D623424065E for ; Wed, 1 Feb 2023 14:26:01 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1675257961; bh=tHMLBT8p0HhLpQ0WYh03wM3bQqI+KjLHRbtqpwmMbOU=; h=From:To:Cc:Subject:Date:From; b=GwOEnZUtJtEFeFXIXrUdrEI4VGRZpbn7XYYN5h4z8dwSPwp0k6cQKfI67mwQH2HHV o6KQ7Zsow19AV4kOB4mjCTwCO6szbS8xjiB4YuybpHeWyoXr4iRWK3HGzW6JqqwKxP dD1nkZ4QUWzmp+8WlB6SDrORdrtZMFLwhzKwoYLwRyc3XZeCu/UsPAWIlzrv29aSu2 LO3IdNEtIUbCToO0HxV/njeELGNJFfy45fEmNNUqEJvEvteBRXan7OiTopc3kbHTmd mdcOPTConlRp8ysPX6sdnV7miIRane9hb1sBkRH+RgwwjVk7YLeWKhEqlXvU8gUM8f sHuYnHkPb16qw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4P6N3D6hrpz9rxH; Wed, 1 Feb 2023 14:26:00 +0100 (CET) From: Ihor Radchenko To: Christian Moe Cc: emacs-orgmode@gnu.org Subject: POSIX TS spec reverses the meaning of TZ offset compared to ISO (was: [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda)) In-Reply-To: <87o7qdsf7h.fsf@christianmoe.com> References: <87fsc88aq9.fsf@localhost> <63c7dd3d.170a0220.6b4d6.f84f@mx.google.com> <877cxk6oeu.fsf@localhost> <63c86454.170a0220.80970.652d@mx.google.com> <63c8f5a6.170a0220.ea8cf.7f96@mx.google.com> <63c9b654.170a0220.d82d2.4254@mx.google.com> <87mt6e86sr.fsf@tsdye.online> <63c9d976.620a0220.a7d40.113b@mx.google.com> <87tu0mjb24.fsf@tsdye.online> <63ca1283.170a0220.5bc81.0fdd@mx.google.com> <87pmb9k8oi.fsf@tsdye.online> <3035CDD5-41DD-4516-9E4E-9E0DF16BE2E0@gmail.com> <87lelo8c9r.fsf@localhost> <2150768.1675077958@archlinux> <87tu063ox2.fsf@localhost> <87r0v9sio1.fsf@christianmoe.com> <87edr9lgq6.fsf@localhost> <87o7qdsf7h.fsf@christianmoe.com> Date: Wed, 01 Feb 2023 13:26:36 +0000 Message-ID: <87v8kljz3n.fsf@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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=1675258216; a=rsa-sha256; cv=none; b=JzYJVxrrA/CPD67kfify/dChtZEiJPMvIZTB8aWQ2R/bhl6yv+7F8Y4rI/63OaZqWum+0D ZTl6v0MeGrGd32oMGRCbHUhdh9R6oJhw6pFjIhD4gcCVdNKhvfsV4fEVEImqizjJSf+SEo 7S2EaGge93x/5LCXd9WzmPgI4zvzpoqs2wkNIj1E98+PNOCJHuZU3Ekejdfdh3Uc1KELL9 gBGGsA1nWwlM1yM2h844fJrWLQUG2VYnsf9f32QOSRVJU+BKg6xfJiR2aY6jSRHuCPdfUy UKxIzglxzI+jV7ljpuTuvP5wgbQnMXDweHnCsnidcECF5+inQKBSQ+GGPS9/nw== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=posteo.net header.s=2017 header.b=GwOEnZUt; 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=1675258216; 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:dkim-signature; bh=FFqAHTAxUDLZBxTohxDN6IOnGnNapVNga0K7vy/3Kjs=; b=M0YzjW7xaB2JvFBXeRETYK6mqP5irXaz8tmMwfu5zHVkdW8FjzApPvbfVg1L3P2lDWgjmf LLKvH20vqe/pAWKq2fKoXuASCcOc4H33YIWXB6/5T1aOL65SJX4NCtjEUoJ6v1h7QQnlHy 3kppy4WWoiLOn0RtVkgrbSwEAZRppR9v3Gney4AvM52/1Syb9WsmnpgJx6H3lII9ZpTv37 E4gCwHYnkMV7cEB64ewoZDPi/0ThJjxQrNInmoClqeSBX0tf3E4d9XBQx5Y1fiSWjE2fql mdsuB2lnNCvTGkR9XILg9kc3u9jBmbe8Q89mP2q58mAyzmUZeQVsMfLIrBKqWA== Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=posteo.net header.s=2017 header.b=GwOEnZUt; 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-Migadu-Scanner: scn1.migadu.com X-Migadu-Spam-Score: -2.98 X-Spam-Score: -2.98 X-Migadu-Queue-Id: 141DD869B X-TUID: ioDwG780YAq0 [ adding Org ML back to CC ] Christian Moe writes: >> Note, however, that because we are conforming to POSIX TZ, @UTC+2 is two >> hours _behind_ the Greenwich. > > Ouch. This is probably something we need to discuss further. Dear All, There is potential confusion coming from the different interpretations of the time zone offsets used in ISO8601 and POSIX TZ specs: https://en.wikipedia.org/wiki/ISO_8601#Time_zone_designators: Negative UTC offsets describe a time zone west of UTC=C2=B100:00, where the civil time is behind (or earlier) than UTC so the zone designator will look like "=E2=88=9203:00","=E2=88=920300", or "=E2=88= =9203". https://www.di-mgt.com.au/wclock/help/wclo_tzexplain.html:=20=20=20=20 [Asia/Beijing] TZ=3DCST-8 Minutes and seconds are optional, so CST-8 and CST-08:00:00 mean the same thing. Note that the sign convention (+/-) used in a Posix TZ string is the opposite to that used in Internet time offsets (RFC 3339) and in Arthur David Olson's TZ data files. So, the equivalent time zone offsets in, say, Singapore will be: [2023-02-01 12:00 @Asia/Singapore] [2023-02-01 12:00+08] ;; local time 8 hours earlier than UTC as in ISO8601 = spec [2023-02-01 12:00 @UTC-08] ;; UTC is 8 hours earlier than local time as in = POSIX TZ spec This is potentially confusing. We may, in theory, reverse the meaning of @UTC[+-]NN manually, but then values like @EST+5 will remain reversed, again creating the confusion. Or, if we reverse everything in @..., users more familiar with POSIX TZ will get confused. Any ideas? --=20 Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at . Support Org development at , or support my work at