From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp11.migadu.com ([2001:41d0:8:6d80::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms5.migadu.com with LMTPS id GOEKM2Y22mPzTwAAbAwnHQ (envelope-from ) for ; Wed, 01 Feb 2023 10:52:38 +0100 Received: from aspmx1.migadu.com ([2001:41d0:8:6d80::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp11.migadu.com with LMTPS id aJP5MmY22mOFfgEA9RJhRA (envelope-from ) for ; Wed, 01 Feb 2023 10:52:38 +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 8BC318D14 for ; Wed, 1 Feb 2023 10:52:38 +0100 (CET) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pN9mr-0003LK-NR; Wed, 01 Feb 2023 04:52:17 -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 1pN9mn-0003Ks-3U for emacs-orgmode@gnu.org; Wed, 01 Feb 2023 04:52:13 -0500 Received: from mail-pf1-x429.google.com ([2607:f8b0:4864:20::429]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1pN9ml-0002fP-39 for emacs-orgmode@gnu.org; Wed, 01 Feb 2023 04:52:12 -0500 Received: by mail-pf1-x429.google.com with SMTP id z3so12217302pfb.2 for ; Wed, 01 Feb 2023 01:52:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:from:to:cc:subject:date:message-id:reply-to; bh=+IFA2Xh8fYUjcW3k+q/tHoyXAYbWSjSFXIK9lQSlFY4=; b=NPzU+RLTehAbOkrqiOUcUEckzeYqZjx5qy60KwhOCzSwTZaaj5ynkiaMhsfEN7XQZI ulvljNKFpgOVfA8qRRi7Rm0+aJiIxPVWJO3euQ3PJPMWxfuoGunEMT8/Tp5i1sbg5Kqe wilH5V6E7gNU8zuj0mVbpapfeng5eyW11MAB5mB7oOvUV5JQCsk90cIkwu4r6E8cpPb3 XkDxpurF0UNsgFhWaoRhLSNJFXutXxSj90DMlDeyAtYhMYWgC5/eoNiVMGZuxGTB4RCM kJCvRvbgJ8zsyRWpIhu1Prz1E9PJF8zYlLneyahuFo6JR1N+dvqEaoKjm9GBnR+IPl6z ZDDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=+IFA2Xh8fYUjcW3k+q/tHoyXAYbWSjSFXIK9lQSlFY4=; b=v0l6BRIzS4vb/HvitVX9GObl+DOVjO5btVDd6WWU5ealRb2tcUoqR774Ji9KsSHZrp kfsBNM4zdxRDTl5qBsLKveyhvq1yqkyFdCrar9VladRdowRm8kUr8IoEmoyraWmzU4Gg 20DaSQGrkMzV4IuVhAeJPtLG2lyoUEYW0J+M7uOYqlv2Y9VnO+U55KRNJ/SOvo0ylW/s l2qzdh64o6nFS5uweCco627kvIc376w7eFoS61MQCst7i/A2Rj+BkWb3Fd9E6FptXR+p xTA2GEKM8jj370quZXND/TjUI/KBoLVgZswWeOh7SoNO1ZSwRLNHSNR1mMR6O+FbXXgU OfiA== X-Gm-Message-State: AO0yUKWKx6eo11PJWfZHDvMti1B3WmzTyiPU+34fG9dUgryI0aqctF7o TsZYglcUMpHXpRnEy82rklqlrLKYKEIJGA== X-Google-Smtp-Source: AK7set/GnIyuirO68xXL+Mj2OhmQVitpgyJ/LvgK0mSmmebDeRWvvjYcxhIUtuxxGUWXesRNVNyvpA== X-Received: by 2002:aa7:8494:0:b0:593:da68:c521 with SMTP id u20-20020aa78494000000b00593da68c521mr1573987pfn.18.1675245128866; Wed, 01 Feb 2023 01:52:08 -0800 (PST) Received: from dingbat (124-169-47-98.dyn.iinet.net.au. [124.169.47.98]) by smtp.gmail.com with ESMTPSA id b17-20020aa78ed1000000b00580e3917af7sm10964577pfr.117.2023.02.01.01.52.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Feb 2023 01:52:08 -0800 (PST) References: <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> <87h6w63jgg.fsf@localhost> <86wn51g661.fsf@gmail.com> <87357pn57t.fsf@localhost> User-agent: mu4e 1.9.19; emacs 29.0.60 From: Tim Cross To: Ihor Radchenko Cc: tomas@tuxteam.de, emacs-orgmode@gnu.org Subject: Re: [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda) Date: Wed, 01 Feb 2023 20:38:52 +1100 In-reply-to: <87357pn57t.fsf@localhost> Message-ID: <86sffpg1bv.fsf@gmail.com> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=2607:f8b0:4864:20::429; envelope-from=theophilusx@gmail.com; helo=mail-pf1-x429.google.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, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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-Flow: FLOW_IN X-Migadu-Country: US ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1675245158; 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=+IFA2Xh8fYUjcW3k+q/tHoyXAYbWSjSFXIK9lQSlFY4=; b=rOXWjHjhLBiGa73eApD8/2pB6tNRI4RqF0li1Ms8R2xMdIg78gpkYRa2AO8og1oUjI+JTO lHUITEzlIrqDgyQdukbRQVp8Bb9UWELCwSnmi/YUWOolMT+ooalGt3gSpJsCYCPQT1/fiH zp1rKw3+PYP24j7p0C5ywWyaqTO5m0RHMQBzjxeRC7W0pGXVCajNTs67F44G+iLI0Tw572 fSQNYA4TfrxBv4h5kuFWGITLsy0xhgQWywwj+tUGXcbzXsqyvCoNuohXh5tmW4jKiHAGlG Q5im/NfIoeZX23yNve+4rmWTF01mjEu7cDQGY5ZgJfA7g9C4bgTvaGEjY/oFgg== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=NPzU+RLT; 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=gmail.com ARC-Seal: i=1; s=key1; d=yhetil.org; t=1675245158; a=rsa-sha256; cv=none; b=id041bi9UePBkfTU5cEwYAIqj+wQ317TToMct++6wHhvM84N586VCCjqfgkBwd7kdqCDOn F+BS+T1dxVxZBt7Jr4QCOjkNLXCFTseIrPVGqV00HIto4npZJ57PeEsvJ66gLBRID6bvNJ 57+S2nWmAuxs3mJ7Zz5TNtMox/7c4Xl4+b59g2kjl/QF4ZLRUg44JTwrnPXNsTQQSom9rE z13BxDs52uV1HGzOp6xAM7fkIoMjo+aA05FxyqxljzRfz3ysGnW6QrdC3lZWCtWeSWn0z8 BS8Gtu+pNug1ug+JwocYsAdfB+9vE1Oqbb+b/PU6YuLGMZ4+eC+71oOcZGW0dg== Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=NPzU+RLT; 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=gmail.com X-Migadu-Scanner: scn0.migadu.com X-Spam-Score: -10.06 X-Migadu-Queue-Id: 8BC318D14 X-Migadu-Spam-Score: -10.06 X-TUID: 46Zl3qnyiNZU Ihor Radchenko writes: > Tim Cross writes: > >>> Either I understand you wrong, or you don't know what you are >>> talking about. 2023-03-23 02:30 @Europe/Berlin refers to /two/ >>> points in time, thus it /is/ ambiguous. If you use disambiguating >>> "time zones" (MEZ vs MESZ in this case) you can resolve that. >> >> I think the confusion relates to context interpretation. If you see >> @Europe/Berlin in isolation, then it is ambiguous as it can refer to two >> different time zone definitions (standard v daylight savings). However, >> if you consider it in conjunction with a date and time, as in 2023-03-23 >> 02:30 @Europe/Berlin, then it isn't ambiguous - in that case, it really >> just says 'Lookup the time zone offset in the databse for Berlin as of >> that date and time. >>... >> Personally, I cannot see the use case of including both a fully >> qualitifed time zone (as in @Europe/Berlin) and an offset... > > Let me try to explain better. Just specifying time zone is ambiguous > once per year during daylight transition. > > [2023-03-29 02:30 @Europe/Berlin] is special. > > According to https://www.timeanddate.com/time/zone/germany/berlin, > 2023-03-29 is the time when the clock is shifted one hour back due to > the daylight saving transition. The wall time goes like > > 2023-03-29 02:30 -> ... -> 02:59 -> (CEST -> CET) 02:00 -> ... -> 2:30 (again!) > > So, [2023-03-29 02:30 @Europe/Berlin] can mean two time points: before > and after the transition. Specifying explicit offset is thus necessary > in this specific scenario to disambiguate the timestamp: > > [2023-03-29 02:30+2 @Europe/Berlin] (before transition) > [2023-03-29 02:30+1 @Europe/Berlin] (after transition) OK, in that case, I think what we are in danger of here is letting the perfect be the enemy of good. The problems of daylight savings transition points is fairly well understood and I think it is fairly well accepted that there is ambiguity arising from the use of daylight savings. The real question is, can the additional complexity associated with including both a time zone name and an offset be justified in order to handle the very small number of time stamps which will fall within the daylight savings transition hour for those locations which have daylight savings? Keep[ing in mind that the complexity is less to do with the time stamp format and more to do with using that information in any meaningful sense. This, combined with the reduced readability of such time stamps and increased possibility of user confusion leads me to question if allowing time stamps with both offset and time zone together in the one time stamp is worthwhile.