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Dye" To: Tim Cross Cc: "Thomas S. Dye" , Max Nikulin , emacs-orgmode@gnu.org Subject: Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda Date: Fri, 20 Jan 2023 14:37:33 -1000 In-reply-to: <63cb3036.170a0220.3ea60.3a93@mx.google.com> Message-ID: <878rhwk8jk.fsf@tsdye.online> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - box2035.bluehost.com X-AntiAbuse: Original Domain - gnu.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - tsdye.online X-BWhitelist: no X-Source-IP: 50.113.33.148 X-Source-L: No X-Exim-ID: 1pJ2DQ-001KqT-O2 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cpe-50-113-33-148.hawaii.res.rr.com (poto-foou.tsdye.online) [50.113.33.148]:46862 X-Source-Auth: tsd@tsdye.online X-Email-Count: 3 X-Source-Cap: dHNkeWVvbmw7dHNkeWVvbmw7Ym94MjAzNS5ibHVlaG9zdC5jb20= X-Local-Domain: yes Received-SPF: pass client-ip=74.220.216.123; envelope-from=tsd@tsdye.online; helo=alt-proxy28.mail.unifiedlayer.com X-Spam_score_int: -15 X-Spam_score: -1.6 X-Spam_bar: - X-Spam_report: (-1.6 / 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, FROM_SUSPICIOUS_NTLD=0.5, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_PDS_OTHER_BAD_TLD=0.01 autolearn=no 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=1674262790; a=rsa-sha256; cv=none; b=A5wvCDLvFD3Yerson6OvlEVce2+NC1f8713agwJ6fxU2KxAAT50K/J7FfoslaNifuI0/k9 PORJYpzYzaOjnuV4VDBurJ5QajTHiUpLW6jMN0jmirIcLFvougd8aViVy+co/7gxPxB1KV J5RRalkn45rZgDo1EcRiATY8u4a2+g9rb/QDafmoJf6a0vLL1G2SxtmE8Oi3AQ+SH5PcGX iRNNIhDX7W/5DV/4qU0j+VRMh86WNZAeUp/bRid2rLl4yechSMW35iJ3V+2ox5zRuH6hiw uTtulSjpAxS1VRcvGF06NMcQK6l0Do5PJNe0MrnVSsbxrvfmi3JGm7y2TD1PYA== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=tsdye.online header.s=default header.b="nl/5XaGz"; dmarc=none; 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-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1674262790; 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=MHIH+UhVXxo9SzvOvUen/2FKlQOn6blRo2BCk4W7NSg=; b=SLiSUAV3ngG+iw6soxp6XEGgJf8ZabSlmyojxE25EUQuJ+hsEYzMZ1wVxlP38qUtmuKDmU bLkYb7rze5u3aZ2Kd0qc9tiQOkVFRO0tkdC6g2yuNk0TquNKQOfKwRknUcqHNVVcC+WOF9 MmSgyZnX5czuuH8aIjmaCRrv8X1yAgSvDcvsJDHG0IzloC3vU+bCd96GwlMiHUc0nsJ051 auGHkgG2ZdyjjjoJFF7yRGFs+wy5sYT5QipWHSY2CxP82o6tJbSkHI+GwyfgUVrfigvElE fyOL0oTYOAlb/O038LXaIiGaL7Pu80VW4+jR+uip7YTO+DmcWSF3Fi/l1eWUpg== X-Spam-Score: 2.29 X-Migadu-Queue-Id: 8CD2539605 Authentication-Results: aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=tsdye.online header.s=default header.b="nl/5XaGz"; dmarc=none; 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-Scanner: scn0.migadu.com X-Migadu-Spam-Score: 2.29 X-TUID: Dp6Y8Y6ReWLX Aloha Tim, Tim Cross writes: > "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=20 >>>> to UTC before the >>>> conference takes place, >>>> then everyone who participates in the conference must notice=20 >>>> this (or miss the >>>> start of the conference). >>> >>> My point is that if timestamp is stored in UTC than it becomes=20 >>> incorrect in the >>> case of time offset change. If such timestamp is stored as=20 >>> local time + time >>> zone identifier then application presenting the timestamp to=20 >>> users will show >>> correct time as soon as zoneinfo data is updated. >>> >>>> A virtual conference is organized by someone in Amsterdam,=20 >>>> who sets a start >>>> time corresponding to 9AM in Amsterdam at a date some years=20 >>>> in the future and >>>> invites participants from all over the world.=C2=A0 Now, if=20 >>>> Amsterdam's timezone >>>> arbitrarily changes its relation to UTC before the conference=20 >>>> takes place, >>>> then must everyone notice this?=C2=A0 Or, should Org, from the=20 >>>> 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=20 >>> support them. It is >>> matter of negotiation between the committee and the=20 >>> participants. Timestamp >>> 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=20 >> UTC or a time zone; and 3) >> Event not relative to user, where the timestamp includes the=20 >> relevant time zone. >> > > I would argue case 2 is really just a specialisation of case 3=20 > i.e. it > has an implicit time zone which is the user's local time zone.=20 > Case 2 covers things the user wants to do at a particular time,=20 regardless of where they are and the time zone they are in. For a=20 repeating task the time zone might change from one instance to the=20 next. It needs to follow the user around and can presumably rely=20 on software to keep track of that. >> For completeness, Case 3 might benefit from a procedure to=20 >> change the relevant time zone. >> For instance, when the boss has scheduled time for you at 9:00=20 >> AM her time, but doesn't >> know where she will be on that day. >> > > If it is to be a fact-to-face meeting (event), implying it=20 > therefore has > a location, you would assume your local time zone. If not=20 > face-to-face > (occurrence), it needs a UTC offset in order to ensure same=20 > point in > time for all participants. The boss either needs to specify the=20 > time > zone they are referencing the 9am to or the user will need to=20 > make a > guess, which may or may not be correct. Or, it might be a recurring virtual meeting that the boss wants to=20 initiate at 9:00 AM her time, regardless of the time zone she=20 happens to inhabit, as might happen on a business trip. Here, the=20 virtual meeting is an event because the boss relates it to her own=20 space/time. Inconvenient for employees, but some bosses are like=20 that. Here, the time zone needs to follow the boss around. My current hypothesis is that the three cases are exhaustive. All the best, Tom --=20 Thomas S. Dye https://tsdye.online/tsdye