Re: Predictable Internet Time

Cyrus Daboo <cyrus@daboo.name> Tue, 03 January 2017 18:03 UTC

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Date: Tue, 03 Jan 2017 13:03:13 -0500
From: Cyrus Daboo <cyrus@daboo.name>
To: Phillip Hallam-Baker <phill@hallambaker.com>, Stewart Bryant <stewart.bryant@gmail.com>
Subject: Re: Predictable Internet Time
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Hi Phillip,

--On January 3, 2017 at 12:42:42 PM -0500 Phillip Hallam-Baker 
<phill@hallambaker.com>; wrote:

> 1) TAI: Use this and only this for any and all purposes that involve
> recording the time an event took place. Including forensic and scientific
> purposes.
>
> 2) PIT: Use this for inter-machine communications. It may also be used to
> present TAI in a human readable form because the mapping from TAI to PIT
> is fixed.
>
> 3) Local Time Zones: For human display purposes

Please note that local time is needed not just for human display purposes 
but also for handling recurring events that are "anchored" to a local time. 
e.g., you want your thermostat to turn on at 6pm local time every day, but 
that has to account for daylight saving time changes etc. Thus when 
defining future data/time values, often (local time & time zone id) is 
required and must be part of the data interchange between devices. Thus the 
need to keep devices up to date with time zone changes (which was the 
primary impetus for the tzdist RFC7808 work).

-- 
Cyrus Daboo