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Dye" To: Jean Louis Cc: "Thomas S. Dye" , Max Nikulin , emacs-orgmode@gnu.org Subject: Re: UTC or not UTC for timestamps in the past ([FEATURE REQUEST] Timezone support in org-mode) Date: Mon, 23 Jan 2023 06:04:52 -1000 In-reply-to: Message-ID: <87edrli4sr.fsf@tsdye.online> MIME-Version: 1.0 Content-Type: text/plain; format=flowed 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: 1pJzqn-004Cz1-Ms 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]:52520 X-Source-Auth: tsd@tsdye.online X-Email-Count: 3 X-Source-Cap: dHNkeWVvbmw7dHNkeWVvbmw7Ym94MjAzNS5ibHVlaG9zdC5jb20= X-Local-Domain: yes Received-SPF: pass client-ip=69.89.24.241; envelope-from=tsd@tsdye.online; helo=outbound-ss-820.bluehost.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=0.498, 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-Authentication-Results: i=1; aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=tsdye.online header.s=default header.b=kWzyFwxT; 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=none ARC-Seal: i=1; s=key1; d=yhetil.org; t=1674492020; a=rsa-sha256; cv=none; b=QSU0qMlRR4jxj8YSjkMS2wnUKknFuXP8t/W7RsPjDzwEj01qZZLjesF7Iv/pAv1XTySNQS lxnKN+K66i3YYIBqT8zBVGnAgcnnbC6eGlt2FqLBuhVs7eqVGhH6iBly/l5MTeGVIZEVuj GNNkh9OmmjFqz9tBt/KHr6QjzfP/GQ7E1Vt9zQNZORt2VBB/rKSF2HrACUiYUTNTzCYsjL DdM52lZDA7EEGznxN0VMB43gpU2W0t4jeCQyDuWrnfReKow3fv0xAIhT0ZyrDTVaR+oT0F JiT3/iMPU9Kkq6KYkTPMen62BPDPIo/Jnu3Ns/hJ48JYGQFgNHDz62uD5QdU5g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1674492020; 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=4sYw9f8ANno2t8y6ZHtKZrmLPryW4ydMSMuvynbL4VI=; b=QRv8wvbKkXst0EJLZAArJWiYJtBzkibWadMWIrYp+AEb7En8TqCwYbEi7LSfOOYKJbG/z+ vxf01+T4hW1r4EjBKetmZByVrQYj6l4/1szolLSNucUJC8CMHbGz36BNYtTAZd7pyuvz3W nWdC8PvJlWDbfY3Uw2758n4Ka/wpsr67g3T+2HeuszXaoK3RZUYcDFElMNQ6xd3TVSfAc+ geaiIdhoaCq3wDaZKOpSCPXNIFKc83Ex1AlrOkqn48Jnb/4ezVUY8vNZ96YnUnHA5xAeFE dx7uq755PE7TeY/Vxe5E7BlzoBIf9bmeWmRfzoGA5drRBTI+mhPBxIt6Ym+/+w== X-Spam-Score: -3.38 X-Migadu-Queue-Id: C078D465F0 X-Migadu-Scanner: scn0.migadu.com Authentication-Results: aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=tsdye.online header.s=default header.b=kWzyFwxT; 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=none X-Migadu-Spam-Score: -3.38 X-TUID: u5GKE7TABj5B Aloha Jean Louis, Jean Louis writes: > * Thomas S. Dye [2023-01-22 20:36]: >> > After all, for a person in Berlin [2023-01-22 Sun >> > 08:29@+1100] may >> > tell more than [2023-01-22 Sun 08:29@Australia/Sydney]. >> >> I'm not sure to follow this. IIUC, the timestamp with offset >> refers to >> absolute time, whereas the timestamp with the Australia/Sydney >> timezone >> refers to a region of space/time whose relation to absolute >> time is fixed >> for any moment, but potentially variable over time. > > I understand above that it is easier understandable when reading > [2023-01-22 Sun 08:29@+1100] as it is assumed by poster (I guess > Max) > that user will understand that there is +11 hours ahead. > Yes, the offset here is ambiguous--is it offset from some timezone or from UTC? > That is assumption by poster. I do not find it easier. > > As when user sees 08:29 that user will think of time in Berlin, > of > time which is not in UTC, and not time in UTC plus 11 hours. > > What is easier is what is generally accepted in any type of > software > worldwide, just represent it in local time zone. > > Difference between offset time and time with time zone is that > time > zone includes rules of daylight savings and other anomalies. Right. The difficulty with scheduling is that it has to take into account two time zones in some cases. Here is a proposal for a terminology of events that honors Ramsey's distinction between events and occurrences and hopes to cover all of Org's use cases. * Kinds of event - No-host event :: An event that takes place at an absolute time. Participants must know their local timezone offset from UTC. Example [2023-01-23 06:00@UTC]. - Situated event :: An event that takes place at a time local to the event site. Participants must know their local timezone offset from UTC and the event site timezone offset from UTC at the time of the event. Example [2023-01-22 Sun 08:29@Australia/Sydney]. - [Itinerant | Traveling | Mobile] event :: An event that takes place at a time local to the event site, which might change after the event has been scheduled. Participants must know their local timezone offset from UTC and the event site timezone offset from UTC at the time of the event. Examples might be a regular staff meeting that takes place at 9:00 AM wherever the boss happens to be, or a proposal to meet with a traveler when it is noon on Sunday for the traveler. Example [2023-01-23 06:00]. In this case timezone is set according to user timezone preference in scope. The Org user should be able to toggle timestamp representation. In the case of a no-host event, user might toggle between UTC and local time. In the case of situated or itinerant event, user might toggle among UTC, local time, and local time at the event site. WDYT? All the best, Tom -- Thomas S. Dye https://tsdye.online/tsdye