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Dye" Cc: Max Nikulin , emacs-orgmode@gnu.org Subject: Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Date: Sat, 21 Jan 2023 11:14:29 +1100 In-reply-to: <87cz79j5gu.fsf@tsdye.online> 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::62b; envelope-from=theophilusx@gmail.com; helo=mail-pl1-x62b.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=1674260589; 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=UOa6oH5p29daGrTa5GI+vHoxvjpn3d/MVB3iYQHtvjo=; b=Un1/zgNukm0Ra+Cw3QSpbRCEP9JjEwj9b3+svDERfNmykSR3L01mi6rKgL2cfVkZW02B43 sOI2vBlESTgA4YIsUx/VkksfhKPNkx8OU/b+Ayi4OB1ge/L+tnuU8fh68oJfTzp8kvZTn5 3EJwLxM3g0cljwJsk7PdcZPuJI6D2eVzx+A6uCVUD0wyU2+Ut/gbmFb5b5hSltDjZhwUT+ e7E/peL/26Jko0KTkwM/l1T9B298px3FWwC3SsNkZRw4k86t0qJ8NSwFa3DsdBtsGXoG3e 1imsYvaeyo/mxPN+LIN5tagoVn6n1XD9aZNSA4Sy53wTvMmKvaWPf4ONYlepDw== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=GWZGo3V9; 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=1674260589; a=rsa-sha256; cv=none; b=daB44xLYN479g8wtDmFGyiGZbMcP/Ieh3UeWAYO6+imyI9rZJaZ+jYGiwERGM1jRqhDphM uZA53XTRbapbmv72HHrff4dwffeEjbQ2EnhxisLFHyU4cwh0Ogx86gFNh1dgRp6V6bwT0W jnZ/Ycn7iNbVSEtf5ytQgRjLqd/m5UYo6f2+D3c/RZ8B/Ul7i8GjeSL49zceZk1of25jEk qB75hP6AfppH0Io+eUyjCtlsAnBzuwVJ6VLrsVNf+NAbXK7pJzxI/8645mNZh/RcxkNC1i h1rBBNs4IzJ24HfzY/ffal8QzXzj2BP2xc5UibboFy4hwq6Z3VO2Omkg1Y4LdQ== X-Migadu-Scanner: scn1.migadu.com X-Migadu-Spam-Score: -4.77 X-Spam-Score: -4.77 X-Migadu-Queue-Id: 1D5EE38740 Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=GWZGo3V9; 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-TUID: HUb6kVSWlzCc "Thomas S. Dye" writes: > Aloha Max, > > Max Nikulin writes: > >> On 20/01/2023 23:09, Thomas S. Dye wrote: >>> Max Nikulin writes: >>> Now, if Amsterdam's timezone arbitrarily changes its relation to UTC be= fore the >>> conference takes place, >>> then everyone who participates in the conference must notice this (or m= iss the >>> start of the conference). >> >> My point is that if timestamp is stored in UTC than it becomes incorrect= in the >> case of time offset change. If such timestamp is stored as local time + = time >> zone identifier then application presenting the timestamp to users will = show >> correct time as soon as zoneinfo data is updated. >> >>> A virtual conference is organized by someone in Amsterdam, who sets a s= tart >>> time corresponding to 9AM in Amsterdam at a date some years in the futu= re and >>> invites participants from all over the world.=C2=A0 Now, if Amsterdam's= timezone >>> arbitrarily changes its relation to UTC before the conference takes pla= ce, >>> then must everyone notice this?=C2=A0 Or, should Org, from the time the= arbitrary change is >>> made public, simply adjust the conference time for all the >>> participants in the Amsterdam timezone? >> >> Both variants are possible and a planning application should support the= m. It is >> matter of negotiation between the committee and the participants. Timest= amp >> should be stored in UTC only in one case. > > Agreed. So, IIUC, there are three cases: > > 1) Occurrence, where the timestamp includes UTC; > 2) Event relative to user, where the timestamp does not include UTC or a = time zone; and 3) > Event not relative to user, where the timestamp includes the relevant tim= e zone. > I would argue case 2 is really just a specialisation of case 3 i.e. it has an implicit time zone which is the user's local time zone.=20 > For completeness, Case 3 might benefit from a procedure to change the rel= evant time zone. > For instance, when the boss has scheduled time for you at 9:00 AM her tim= e, but doesn't > know where she will be on that day. > If it is to be a fact-to-face meeting (event), implying it therefore has a location, you would assume your local time zone. If not face-to-face (occurrence), it needs a UTC offset in order to ensure same point in time for all participants. The boss either needs to specify the time zone they are referencing the 9am to or the user will need to make a guess, which may or may not be correct.