timestamp notation @gnupg.org

MFPA expires2011 at ymail.com
Sat Jun 18 23:44:01 CEST 2011

Hash: SHA512


On Saturday 18 June 2011 at 5:24:45 PM, in
<mid:BANLkTik1W3nTc17Dy=PeefiTkgkhvVBGvQ at mail.gmail.com>, Jerome Baum

> See
> http://tech.groups.yahoo.com/group/ISO8601/message/226
> for details (be sure to look at the other replies as
> well).

Like most discussion threads, I see opposing views represented there.

> I don't have ISO 8601 handy, so I can't speak
> first hand. However, this example seems very rational:

> "The 20th Century 1901-01-01 / P100Y
> 1901-01-01 T 00:00:00 / 2001-01-01 T 00:00:00"

I would prefer to say the century finished at 2000-12-31T24:00:00. (-;

Also, I think 1901-01-01T00:00:00/2001-01-01T00:00:00
would be equivalent to 1901-01-01T00:00:00/P100Y,
and 1901-01-01/2001-01-01 would be equivalent to 1901-01-01/P100Y.

They are different in the same way as 5 Euros is different to
5.00 Euros.

>> What about time zones? Lets say person A, signing the
>> document, has a local time offset of GMT+2 and person
>> B, receiving the document, has a local time offset of
>> GMT+1. Person A has their app set to round down to the
>> beginning of the day, which in person B's local time
>> is 23:00:00 on the previous day. I guess person A
>> seeing 20110618T000000/P1D and person B seeing
>> 20110617T230000/P1D is a non-issue, since the two
>> refer to the same time interval in UTC.

> Ah, we've been careless. Append a "Z" to your dates and
> they are UTC (or append a timezone, if you want that).
> Those two intervals are actually ambiguous AFAIK. We
> could specify either:

> 1. All times must be UTC ("Z") or have a timezone; or

Aren't the timestamps recorded in the signature packets as unix time
[1], and displayed in the local time detected from the user's system?

> 2. Ambiguous times are interpreted as UTC.

I think the ISO 8601 standard assumes local time unless otherwise
specified. So it makes sense for each person viewing the signature to
see the timestamp in their own local time if no time zone information
is included.

20110618T000000+0200/P1D and 20110617T230000+0100/P1D both refer to
the same time period without ambiguity.

If people feel there is ambiguity here, maybe this is best dealt with
by adding some simple text to the GnuPG output to indicate that times
are shown in local time, as per the user's system.

[1] http://tools.ietf.org/html/rfc4880#section-3.5

- --
Best regards

MFPA                    mailto:expires2011 at ymail.com

What's another word for synonym?


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