ISO-8601 compliance (Re: Why and when storing local time?))

Bernhard Reiter bernhard at
Wed Mar 23 11:16:43 CET 2011

Am Dienstag, 22. März 2011 23:26:18 schrieb Jeroen van Meeuwen (Kolab Systems):
> I think you're mistaken in the perception that:
>   20110322T220000

I was thinking about using "2011-03-22T22:00:00", as the example
above does not match the rules I've proposed in
But I guess this is irrelevant to the discussion in this thread.

> to indicate a local time with is somehow ISO-8601 compliant. 

As far as I can say it parses Appendix A. ISO 8601 Collected ABNF
of rfc3339. 

> Sure it is compatible with a selected paragraph, 
> but ISO-8601 specifically refers to either UTC *or* 
> local time plus the UTC offset, whenever the time is 
> included in the datetime (or in cases the offset is unknown, "-00:00" as
> the offset).

I do not have a copy of ISO-8601 at hand, do you?
In its absense, I have found strong hints 
that it is okay to use the above form
without offset to indicate local time:
has an example coming close:
   Example: 2003-04-01T13:01:02 represents one minute and two seconds after one o'clock in the afternoon of 2003-04-01. 

In addition:
 Specifications applying ISO 8601 can have a need to define the allowed 
 representation of the expressions in a certain data field. For instance a 
 specification might want to define that a certain field containing the date 
 and time of an event should do so in the format: YYYYMMDDhhmm with the 
 exclusion of all other formats allowed by ISO 8601 writes:
  If no UTC relation information is given with a time representation, the time is assumed to be in local time.

And Qt 4.7.2 accepts it:
QDateTime time2 = QDateTime::fromString("1996-12-20T00:39:57", Qt::ISODate);


also writes:
'"Local" or untimezoned times are presumed to be the time in the timezone of some unspecified locality'

'zzzzzz (if present) represents the timezone (as described below).'

which all allow the absense of the offset for good.


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