Re: What day is 2010-01-02 (and what time is it)

On 18 mar 2010, at 17.38, Marshall Eubanks wrote:

> This is backwards. Most astronomers I know regard UTC as a nuisance. In their 
> calculations, astronomers use TAI (or, if they need to know the rotation of 
> the Earth, UT1). Solar system ephemeris work uses ephemeris time, for 
> historical reasons (ET − TAI = 32.184 seconds). GPS internally uses GPS time, 
> which has the leap second adjustment appropriate for the start of the series 
> in 1980, supposedly because the GPS program office didn't understand leap 
> seconds (TAI - GPS = 19 seconds).
Hmm...the signal for the GPS include the difference nowadays, right?

But, the largest problem I think are daylight savings, and the fact the 
daylight savings rules change.

We should from IETF point of view review the ical spec, and try to push 
timezone information away from the objects, and to a central repository. The 
timezone offset should be calculated based on the geographical location of the 
event.

I.e. if I (or my application) know something happened at 13:32 on 2010-01-02 in 
Stockholm, that is I claim the best way of stating when something happened. 
Even better example is 13:32 at 2123-01-02 in Stockholm, as the chance 
Stockholm still exists in 2123 is higher than Stockholm use the same daylight 
savings rule then compared with today.

Of course one should be able to say explicit time related to UTC (or TAI ;-) ) 
as well, but...I am tired of all applications that do the wrong thing. 
Specifically in user interfaces.

   Patrik

PGP.sig
Description: This is a digitally signed message part

_______________________________________________
Ietf mailing list
Ietf(_at_)ietf(_dot_)org
https://www.ietf.org/mailman/listinfo/ietf