Re: [Cbor] draft-ietf-cbor-date-tag-02 - handling of time zone offsets

Jim Schaad <ietf@augustcellars.com> Wed, 08 July 2020 04:46 UTC

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From: Jim Schaad <ietf@augustcellars.com>
To: <draft-ietf-cbor-date-tag@ietf.org>
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References: <20200701072123.hnyhzemagtotnuyl@anna.jacobs.jacobs-university.de> <DD477DBD-3F3F-48FA-BADC-FF550CC3D4F7@tzi.org> <20200701090536.mqkfjebfzhz5phls@anna.jacobs.jacobs-university.de> <5244.1593618673@localhost> <04FEC6E5-F8E9-472D-A4D6-71C6C00D79E6@tzi.org> <20200703060820.ydmbdmp5fy2v6wgf@anna.jacobs.jacobs-university.de> <99A557CE-559D-409A-A3DC-5D20F2F55F5E@tzi.org> <20200703064652.m7tuvfcglxyvfque@anna.jacobs.jacobs-university.de> <2A137293-075C-4862-91C2-CC583B9B2FF6@tzi.org> <20200703103212.kwl5pbxubznjqpf6@anna.jacobs.jacobs-university.de> <B4E1605F-4C94-4EC6-B603-0BB725CEF34F@tzi.org>
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Subject: Re: [Cbor] draft-ietf-cbor-date-tag-02 - handling of time zone offsets
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Mike,

Based on the messages that I have seen, I would suggest the following actions:

Create a new section dealing with the following: 
a) a definition of what calendar day means
b) a definition of a term other than Unix Epoch to be used as the basis.  This  is a point in time rather than a calendar day so having this as the basis point seems to be generation frisson.  It would appear that it is better to use 1970-01-01 as a POSIX calendar date epoch.
c) Guidance on how to use two points in time to compute a calendar day count.
d) Information on why it is a bad idea or how to compare a calendar date and a point in time.
e) Guidance on how to compare two calendar dates (this should be easy).

Jim



> -----Original Message-----
> From: CBOR <cbor-bounces@ietf.org> On Behalf Of Carsten Bormann
> Sent: Friday, July 3, 2020 5:11 AM
> To: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
> Cc: draft-ietf-cbor-date-tag@ietf.org; Michael Richardson
> <mcr+ietf@sandelman.ca>ca>; cbor@ietf.org
> Subject: Re: [Cbor] draft-ietf-cbor-date-tag-02 - handling of time zone offsets
> 
> On 2020-07-03, at 12:32, Juergen Schoenwaelder <j.schoenwaelder@jacobs-
> university.de> wrote:
> >
> > PS: There are even events where there is no natural time zone that can
> >    be associated with the event, like the first step on the moon.
> 
> (For those who weren’t there when it happened:)
> 
> Indeed, Monday, 1969-07-21T02:56:15Z.
> 
> Most Americans will tell you Sunday 1969-07-20 for the first steps.   The exact
> time was actually specifically chosen to occur on prime time TV in the US (and
> then was slightly delayed, but managed to stay in window), which spans several
> time zones, which all have this on 1969-07-20.
> 
> Yes, I agree we should have some text on this (not the moon landing, but the
> issues in converting between calendar dates and times anchored on time
> scales).
> 
> Grüße, Carsten
> 
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