From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Dokos Subject: Re: Time-zone in dates Date: Wed, 01 Jul 2015 11:17:17 -0400 Message-ID: <87d20bj4aq.fsf@alphaville.usersys.redhat.com> References: <87zj3moadx.fsf@gmail.com> <87zj3mv9rb.fsf@ucl.ac.uk> <87ioaav72g.fsf@ucl.ac.uk> <87y4j6tgyn.fsf@nicolasgoaziou.fr> <20150626195749.GG5090@fjo-extia-HPdeb> <87zj3iodr4.fsf@ucl.ac.uk> <87egkugfjw.fsf@pierrot.dokosmarshall.org> <878ub1zlzy.fsf@delle7240.chemeng.ucl.ac.uk> <87lhf1i68s.fsf@alphaville.usersys.redhat.com> <87fv581jfv.fsf@ucl.ac.uk> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:34013) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAJlT-0001Lc-G6 for emacs-orgmode@gnu.org; Wed, 01 Jul 2015 11:17:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZAJlP-0001qo-73 for emacs-orgmode@gnu.org; Wed, 01 Jul 2015 11:17:31 -0400 Received: from plane.gmane.org ([80.91.229.3]:42858) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZAJlP-0001qd-08 for emacs-orgmode@gnu.org; Wed, 01 Jul 2015 11:17:27 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1ZAJlN-0000B6-Cw for emacs-orgmode@gnu.org; Wed, 01 Jul 2015 17:17:25 +0200 Received: from nat-pool-bos-t.redhat.com ([66.187.233.206]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 01 Jul 2015 17:17:25 +0200 Received: from ndokos by nat-pool-bos-t.redhat.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 01 Jul 2015 17:17:25 +0200 List-Id: "General discussions about Org-mode." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org Sender: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org To: emacs-orgmode@gnu.org Eric S Fraga writes: > On Tuesday, 30 Jun 2015 at 11:08, Nick Dokos wrote: >> Eric S Fraga writes: >> >>> On Monday, 29 Jun 2015 at 21:17, Nick Dokos wrote: >>>> The only reliable way of doing that is to use UTC as the "internal" >>>> representation and translate to/from local time on external >>>> display/input *only*. In the case of org mode, the "internal" >>>> representation is user-visible, so that can cause confusion and some >>>> head-scratching. But *any* other method is going to be a nightmare >>>> (damhikt). >>> >>> This may be the correct approach although I worry about losing >>> information by only storing UTC. Whether this information loss is >>> important or not is difficult to predict. It may be of ephemeral >>> importance only. >> >> In what way are you losing information? > > Sorry, should have been clear: the time zone information itself. By > reducing to UTC, you lose one bit of information. Whether that matters > or not in practice is not clear but I'm always uncomfortable when > considering data representations that lead to information loss. > > I've been trying to come up with an example that would illustrate the > problem but I've failed so far. > > Funnily enough, the one example I can think of that would be difficult > to manage with UTC is the case of not wanting to specify a time > zone. Somewhat contrived but, for instance, wanting to do something > every morning such as brushing my teeth. This would be, say, at 7am > regardless of which time zone I'm in. If this were stored in UTC, it > would be at a different time depending on where I was at the time. > This is actually a pretty good example. This and Michael Brand's examples make it clear that storing (just) UTC in the file is untenable. Nick