RE: XSD 1.1 issue: when did timezones cease being durations?

At 3:25 PM -0500 050301, C. M. Sperberg-McQueen wrote:

>  > If that means you've stored one integer that is a multiple of 60 between
>>  -50400 and 50400, rather than storing one integer between -840 and 840,
>>  then we're quite close--I don't see that it matters much.  But a
>>  dayTimeDuration value is not an integer, it's a pair of integers.  Is
>>  that really what you want to store?
>
>Who's talking about storage?

RTFM.  At 11:22 AM -0800 050301, Ashok Malhotra wrote:

>2.  F&O changed it behavior as of this morning.  The timezone 
>component is now stored as
>a dayTimeDuration e.g.  PT5h30m.

Returning to your msg:

>You mention a bug found earlier in the idea that
>timezone information is a duration; at the risk
>of replowing well known ground, can you remind
>the rest of us of what it was?

RTFM again, dammit!

At 2:10 PM -0500 050301, I wrote:

>THE REASON THEY WERE CHANGED IS SIMPLE:  TIMEZONES ARE NOT THE
>SAME AS DURATIONS--THEY DON'T BEHAVE THE SAME WAY.  CALLING THEM
>DURATIONS JUST BECAUSE THEY ARE SIMILAR TO DURATIONS IS WISHFUL
>THINKING.  TIMEZONES ARE NO MORE DURATIONS THAN FLOATS ARE DECIMALS.
>
>There are four things critical to timezones:  the lexical
>mapping, the canonical mapping, the value itself, and the
>algorithm for adding them to and subtracting them from
>dateTime values.
>
>Of these, the only thing that they *can* have in common with
>is the value.  Since timezones aren't really durations, what
>point is there in replacing an integer-valued property with
>one whose value is a pair of integers, one of which is required
>to be zero?
>
>Pretending a timezone is a duration will--obviously--not confuse
>people into thinking that you use duration lexical representations
>for timezones.  People know better.  But it will confuse implementers
>who will think that they can get correct results using the duration
>addition-to-dateTimes algorithm.
>
>This error was discovered early in the development of the 7-property
>model, and was corrected a long time ago by ceasing to pretend that
>timezones are duration.
>
>Must we replow this ground?

-- 
Dave Peterson
SGMLWorks!

davep@iit.edu

Received on Tuesday, 1 March 2005 20:52:34 UTC