FW: [tc-xml-l] Durations and DST

A clarification from Mike on Durations…

The key statement to my mind is

P2D is not equal to PT48H right through the year

In a similar way, if I am specifying a Month, then I had better count the days myself…

We may wish to conform some types of down-stream uses of WS-Calendar to use Hours only, if it comes to that.

tc
"If something is not worth doing, it`s not worth doing well" - Peter Drucker
Toby Considine TC9, Inc
TC Chair: oBIX & WS-Calendar
TC Editor: EMIX, EnergyInterop
U.S. National Inst. of Standards and Tech. Smart Grid Architecture Committee
Email:

Phone: (919)619-2104
http://www.tcnine.com/ blog: www.NewDaedalus.com
From:
Mike Douglass [mailto:]
Sent:  Sunday, January 23, 2011 10:20 PM
To:  
Cc:  'tc-xml-l tc-xml-l Reflector'; 
Subject:  Re: [tc-xml-l] Durations and DST

From RFC5545
      The duration of a week or a day depends on its position in the
      calendar.  In the case of discontinuities in the time scale, such
      as the change from standard time to daylight time and back, the
      computation of the exact duration requires the subtraction or
      addition of the change of duration of the discontinuity.  Leap
      seconds MUST NOT be considered when computing an exact duration.
      When computing an exact duration, the greatest order time
      components MUST be added first, that is, the number of days MUST
      be added first, followed by the number of hours, number of
      minutes, and number of seconds.
In Java(tm) implementation terms you cold use the Calendar class and work through the fields adding the appropriate values and the class takes account of DST transitions. So a day could be 23/24/25 hours.
If it's important to have an exact number of hours then you specify as hours, that is
P2D is not equal to PT48H right through the year
On 01/23/2011 09:43 PM, Toby Considine wrote:
A duration of 15 days, 5 hours, and 20 seconds would be:

       P15DT5H0M20S

How many hours is that? If one of those days is the 23 hour day (or 25 hour day) to begin oe ened Daylight Savings Time, what is the understanding?


If the Duration starts at 3:00 PM, would it end at 8:00 PM, 7:00 PM, or 9:00 PM

tc
“It is difficult to get a man to understand something, when his salary depends upon his not understanding it”

--
Upton Sinclair.
Toby Considine TC9, Inc
OASIS Technical Advisory Board TC Chair: oBIX & WS-Calendar
TC Editor: EMIX, EnergyInterop
U.S. National Inst. of Standards and Tech. Smart Grid Architecture Committee
Email:

Phone: (919)619-2104
http://www.tcnine.com/  blog:  www.NewDaedalus.com




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Mike Douglass                            
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