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[124.169.47.98]) by smtp.gmail.com with ESMTPSA id u10-20020a170902a60a00b00196807b5189sm902565plq.292.2023.01.29.12.38.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 29 Jan 2023 12:38:09 -0800 (PST) Message-ID: <63d6d931.170a0220.84f9f.11fd@mx.google.com> X-Google-Original-Message-ID: --text follows this line-- References: <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> <63d43ec5.630a0220.87fac.44e2@mx.google.com> User-agent: mu4e 1.9.17; emacs 29.0.60 From: Tim Cross To: Jean Louis Cc: Sterling Hooten , "Thomas S. Dye" , Ihor Radchenko , Daryl Manning , rjhorn@alum.mit.edu, emacs-orgmode@gnu.org Subject: Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Date: Mon, 30 Jan 2023 07:26:01 +1100 In-reply-to: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2607:f8b0:4864:20::102d; envelope-from=theophilusx@gmail.com; helo=mail-pj1-x102d.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-Country: US X-Migadu-Flow: FLOW_IN ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1675024743; 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=aJUc6iMWqbtpbEhcA04+1Eq1YWLkgKYGExFSdovqXJ8=; b=PsY/vsm/1zS2eIt+qEtQRqwXWoLftT9EvxjDeGl64puc3FyZTjt7kHWZ8uZbAcOlkfta4m TntYoYast0yvmvVq5Yg54SERU9gJH1x6fj+ptBBYbFskxUo7pUHHbTISXmXRxCIIpoJFYS +PmMhiZsfhDI7Nfgoou+yxggNrLb14PxJPHPg17W5poZ/6Pim9Vq4rriwDclGQjUTrVykZ Qh6Q1Egedzo1E8elpj8YGO2TPd9EdF+6ZfCYC0IdXHiw2Wwahq7XSypyAclz6Q2WIaia6D 0Zes1nF8Ng0heLfNluEHEtYJ3/4wlCy0gds/UL0d5jFNw0uTgQnVBg+/kWYicQ== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=bltjmj+P; dmarc=pass (policy=none) header.from=gmail.com; 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" ARC-Seal: i=1; s=key1; d=yhetil.org; t=1675024743; a=rsa-sha256; cv=none; b=CqEKTA5x3mdiHR5C1DMrtxX5G6bFhgr6UVX2g8v6Nq+5h24Q32WyLFwewqPkpC1j4615no nSgSvh6lPJabiiHyelEnjWDSLfnieoAQvG8kWfmMetmfrCcmgwDhpB0JzN4EnzN9QvFkyP Pyum7rsBXakLVBZ2u+gXIyMdRvieZQMKO5ya/MQQOIBJWoZ2nB6YUEnMS0FCEe1U8PgfIt nU1bJTGZQMDjGoWV2YLr6lC3tBl8mIoYZGEc3OeYnKTHK82t2KPOkT79lLLC2ObcFwVeEK G4dlhn9aYi3fztq6dk86xCaxV4Q6yQh8HTGWH1XYCpw7UGVG8jnivJfyTrku3w== X-Spam-Score: -6.26 X-Migadu-Spam-Score: -6.26 Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=bltjmj+P; dmarc=pass (policy=none) header.from=gmail.com; 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" X-Migadu-Queue-Id: D86071C3A X-Migadu-Scanner: scn1.migadu.com X-TUID: n8cJCd4jAXbT Jean Louis writes: > * Tim Cross [2023-01-28 00:15]: >> > >> >> What kinds of representations would a calendar system capable of >> >> handling timezones require? >> >>=20 >> >> =E2=80=A2 Instant (fixed) >> >> =E2=80=A2 This is referring to an unambiguous moment in time >> >> =E2=80=A2 e.g., 2007-02-03T05:00:00.000Z >> >> =E2=80=A2 Offset (fixed) >> >> =E2=80=A2 This captures the idea of "when did it happen for the per= son who >> >> made the observation" >> >> =E2=80=A2 e.g., 2007-02-03T04:00:00.000+01:00 >> > >> > Offset is not that fixed, maybe from viewpoint of storage as maybe it >> > is considered fixed in it's representation, but you have to keep in >> > mind that time offset by it's definition is changing itself, suddenly, >> > depending of daylight saving and time zone. >> > >>=20 >> I think your misinterpreting the intent here. If you specify a timestamp >> with offset, it is fixed. > > That is what you say. And I am pointing out to international standard > references. > > If you use offset as "fixed" it means such use would not be by > standard, and you would confusing users and programmers who are using > standard for calculations in programs. > >> It does not change with daylight savings or any other change in >> rules for a time zone. It does not even specify a time zone. > > And while and before making that decision, did you review the standard > that time zone offset is influenced and changed by daylight savings? > > It does not specify time zone. But it is derived from time zone, and > is not same from time zone. > > Are you aware that time zone offset could have "skipped time" or > "added time" due to daylight savings? > > That implies that by using time offset, you would forget daylight > savings which are international standard, and make calculations wrong, > because you started applying own standard in Org. > I think your still misunderstanding what is meant by offset. Yes, a timezone is defined by the offset it has from UTC Yes, a location time zone may change due to various reasons, such as daylight savings time, which also means the offset for that timezone changes. However, it is the time zone definition which has changed. THink of it as a time zone with a new offset rather than a time zone with a chagned offset.=20 When you specify a date+time wiht an explicit offset, that offset is fixed. That date+time is fixed. It will not change when daylight davings comes in or goes out because it isn't a time zone. It is only an offset and has no location reference and therefore no time zone. Saying that an offset is a fixed value is very different from saying that a time zone has a fixed offset. I think this is where your confusion is coming from.=20