Re: [Sedate] Can offsets like [+02:00] be used instead of IANA names in brackets?

Justin Grant <justingrant.ietf.public@gmail.com> Thu, 17 March 2022 17:01 UTC

Return-Path: <justingrant.ietf.public@gmail.com>
X-Original-To: sedate@ietfa.amsl.com
Delivered-To: sedate@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 0F0383A12D2 for <sedate@ietfa.amsl.com>; Thu, 17 Mar 2022 10:01:26 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.107
X-Spam-Level:
X-Spam-Status: No, score=-2.107 tagged_above=-999 required=5 tests=[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, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id TSjYAN3TOOwU for <sedate@ietfa.amsl.com>; Thu, 17 Mar 2022 10:01:21 -0700 (PDT)
Received: from mail-oi1-x234.google.com (mail-oi1-x234.google.com [IPv6:2607:f8b0:4864:20::234]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 31EFB3A12D6 for <sedate@ietf.org>; Thu, 17 Mar 2022 10:01:21 -0700 (PDT)
Received: by mail-oi1-x234.google.com with SMTP id q129so4219661oif.4 for <sedate@ietf.org>; Thu, 17 Mar 2022 10:01:21 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=rS9VMmTfGVNzSeyjKK+YlVjdY3NX5h7gKSPdBZgcssk=; b=F9qn4pGccKT+mg/ChqXmVqQ/QbP/1peH86HOhLZN982Vi5cL7WIjTGxbuTEO0BdmgH P23u1wji9dAX4PKoxIWVya2ahv1Oe9bconQm+iYX2CL7iuR9WfldpSVykQ7OOb/kymyC oIvp9HqDzRfGOItUcvkXhuwIzoq5qF9g8YS2CYG9az9FUfpSc9OXU9WclitjUd5W3Bx1 TDuYX+qFDsMMXBOBzh/CVPSETK77D4y4Apm5U5ZcI5+HpvAJ6Nxb1lSv7cLAZ+ML5RBa o2DSVMkzhWgJLapTfZjG3/Nn/0SYvZJYwoeGzbnq1lzX/FPcEME25uPzuquc9Z4NKZTi s1ZQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=rS9VMmTfGVNzSeyjKK+YlVjdY3NX5h7gKSPdBZgcssk=; b=zNUW2PzKL2nSZmP8tD1Ipxu1Iu4Z9BPAx133aCE0Ak0E/4BiGJ8uv6FNRMIQjDZDOB dA0Ns6/gWyCk7STV5Ql7PiN5fJ8v+tKJxzGBYvD8KhpzWoNDnbs8VioSxzVab/2R15QA gI4do8h/4DKzSWqBmALDjRb6x/+1zyjKwe3VPlDWCIDjIMlTapBw2noe7eo0r8iM1tzX e+hHiZ4ETT2X1Bf87y3e8ItUtliuHTpPfs+4YuQI8ytX88Jv4/ulN2dAYAkyUpPb0lYx GJ+kcIapcA9TyUc3Ht8tHxq/zjJs0m5+w9qEIGaVAC5sFbnll8RyMQV2LbJb+euj2Rus zWWw==
X-Gm-Message-State: AOAM5313U3Iea0f8hzkVGoe6c93cb9W+p1Flj5klWLSE7ybM+kK46AaW /p98hs7i0k0PRXvfdmW/DJo25oNffHCKsRB1j2P1Us+8F1o=
X-Google-Smtp-Source: ABdhPJzNNjY2oYBEpRuZyjfU2jPe4B//LyXVbMZ0nsTpXHnzSkZIc1TYXbq76QsU6bFs5gg+1JMS0OtVXgJ7+NVVfE8=
X-Received: by 2002:a05:6808:683:b0:2ec:a748:8347 with SMTP id k3-20020a056808068300b002eca7488347mr2607306oig.120.1647536479791; Thu, 17 Mar 2022 10:01:19 -0700 (PDT)
MIME-Version: 1.0
References: <CACy7CfhB63dgxatWHYSr-KMKP1SWwd6nRmumCSCPVijgYede4A@mail.gmail.com> <c8035af7-1302-a04a-e449-76db3ad1754e@igalia.com> <6D38910C-72A3-4133-A9BF-794B532765DF@tzi.org> <CACy7Cfgw42p4e0squf0=Ji=RPau+ASeTWd=D6syK5=WUXpfvDw@mail.gmail.com> <A5B6B601-F5B1-469F-B442-3D008519D24B@tzi.org> <CACy7CfhxiOOy0BMdAgx2Jaiomnq6GvEqhamUmOwgdWB6oyKY3w@mail.gmail.com> <63BE08D0-C7C5-4CEA-BBE2-640C8F126661@tzi.org> <f6645a58-74f4-31f4-edd7-85d3d1b91851@igalia.com> <CACy7CfitzT5qDh68P5ZBRDSMAKwSWozWgg9yTJAT2AX9S_VD_A@mail.gmail.com> <VI1PR0202MB34246D8D790A3B6BC4A76E9F870A9@VI1PR0202MB3424.eurprd02.prod.outlook.com>
In-Reply-To: <VI1PR0202MB34246D8D790A3B6BC4A76E9F870A9@VI1PR0202MB3424.eurprd02.prod.outlook.com>
From: Justin Grant <justingrant.ietf.public@gmail.com>
Date: Thu, 17 Mar 2022 10:01:08 -0700
Message-ID: <CACy7CfgwehrwckoG1TuFVCf6c0xvCtiq-QLSzDTAdru9NmvUaw@mail.gmail.com>
To: Edward Welbourne <edward.welbourne@qt.io>
Cc: Carsten Bormann <cabo@tzi.org>, "sedate@ietf.org" <sedate@ietf.org>, Ujjwal Sharma <ryzokuken@igalia.com>
Content-Type: multipart/alternative; boundary="000000000000a1ee5005da6cfa60"
Archived-At: <https://mailarchive.ietf.org/arch/msg/sedate/PbhkIARGZQsONxN52xhtKApDWwY>
Subject: Re: [Sedate] Can offsets like [+02:00] be used instead of IANA names in brackets?
X-BeenThere: sedate@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Serialising Extended Data About Times and Events <sedate.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/sedate>, <mailto:sedate-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/sedate/>
List-Post: <mailto:sedate@ietf.org>
List-Help: <mailto:sedate-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/sedate>, <mailto:sedate-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 17 Mar 2022 17:01:26 -0000

I'm hearing consensus on this thread that it's OK to add offset strings in
brackets, e.g. "2021-12-09T00:00-08:00[-08:00]" in order to be compatible
with prior art in java.time.ZonedDateTime. Caveat: this format is allowed
but is generally not recommended because of the issues noted by @Edward
Welbourne <edward.welbourne@qt.io> and others. Documentation should
discourage but not prohibit use of this format.

Does anyone object?

If not, can we merge
https://github.com/ietf-wg-sedate/draft-ietf-sedate-datetime-extended/issues/12
 ?

Cheers,
Justin


On Wed, Mar 9, 2022 at 2:02 AM Edward Welbourne <edward.welbourne@qt.io>
wrote:

>
> Justin Grant (8 March 2022 21:58) wrote:
> > An IANA name in brackets means "receiver, please use your TZDB rules
> > to decide how to calculate the offset of derived timestamps like "1
> > day later" An offset string in brackets means "receiver, I am opting
> > out of using time zone rules. Instead, every derived timestamp should
> > use this offset."
>
> One warning here: if the sender only tells the receiver the offset of a
> particular time and stipulates another time as "one day later", or
> similar, the resulting time will be expressed relative to that offset
> *which might not match* the sender's time-zone for that time (due to a
> transition in the interval), so may produce different results than if
> the sender had reported their zone's IANA ID.  That is potentially
> desirable in some cases, of course, but the documentation of the choice
> of annotation should make clear that the two forms are not always
> equivalent.
>
>         Eddy.
>