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RE: Lexical and canonical representations of dateTime, et al.

From: Ashok Malhotra <ashokma@microsoft.com>
Date: Fri, 2 Nov 2001 09:48:03 -0800
Message-ID: <E5B814702B65CB4DA51644580E4853FB01488565@red-msg-12.redmond.corp.microsoft.com>
To: <zongaro@ca.ibm.com>, <www-xml-schema-comments@w3.org>
Henry:

Thanks you for reminding us.  As it turns out I have changed my position
on 1 and 3.  

 

Additional digits can be used to increase the precision of fractional
seconds if desired i.e. the format ss.ss... with any number of digits
after the decimal point is supported. To accommodate year values greater
than 9999 additional digits can be added to the left of this
representation. 



[AM] I would like the Schema WG to define a minimal level of
conformance.  I suggest that conformant processors be required to
support 4 digit year numbers and microsecond precision on seconds.

 

3) ISO 8601 specifies that 24:00:00 of one day is the same as 00:00:00
of the following day.  Which is the permitted form in the canonical
representations of the various types?

 

[AM] I think we need to pick one for the canonical representation.

I vote for 00:00:00



All the best, Ashok 
=========================================================== 
Ashok Malhotra              <mailto: ashokma@microsoft.com
<mailto:%20ashokma@microsoft.com> > 
Microsoft Corporation 
 

 

-----Original Message-----
From: zongaro@ca.ibm.com [mailto:zongaro@ca.ibm.com] 
Sent: Friday, November 02, 2001 8:56 AM
To: www-xml-schema-comments@w3.org
Subject: Lexical and canonical representations of dateTime, et al.

 



Hello, 

     I raised the following questions in a note on xmlschema-dev in
March.[1]  Questions 2) and 4) in that note were addressed in the "XML
Schema: Datatypes" Recommendation, but I don't believe that 1) and 3)
were addressed, so I've copied them here so they won't be forgotten. 

     Comments from Ashok Malhotra are prefixed by "AM>>" and responses
from me are prefixed by "HZ>". 



     Sections 3.2.7.1 and 3.2.7.2 of the Datatypes Recommendation define
the lexical and canonical representations of the dateTime datatype,
respectively.  Section 3.2.7.1 states, in part that: 

Additional digits can be used to increase the precision of fractional
seconds if desired i.e the format ss.ss... with any number of digits
after the decimal point is supported. To accommodate year values greater
than 9999 additional digits can be added to the left of this
representation. 


1) Unlike the definition of decimal (3.2.3), this definition doesn't
specify the minimum number of additional year digits nor the minimum 
number of additional digits in the fractional portion of the seconds 
that needs to be supported by a processor.  Does a processor really 
need to be prepared to handle an arbitrary number of digits? 
Obviously this can have a significant effect on an implementation.
AM>> There have been a lot of diffrent requirements for this.
AM>> Scientists want very accurate fractional second values.
AM>> Use a decimal number to represent the seconds part.

HZ>> I don't object to supporting very accurate fractional numbers of
HZ>> seconds; my only question is whether a processor needs to be
HZ>> prepared to support an *arbitrary* number of digits.  The
HZ>> definition of "number" permits a minimally-conforming processor
HZ>> to support as few as 18 digits, but there is no similar "out" for
HZ>> a processor with respect to the number of digits in the
HZ>> fractional portion of the seconds, nor in the number of digits in 
HZ>> the year. 

3) ISO 8601 specifies that 24:00:00 of one day is the same as 00:00:00
of the following day.  Which is the permitted form in the canonical
representations of the various types?
AM>> Both are acceptable.

HZ>> The definition of canonical lexical representation requires there
HZ>> to be a one-to-one mapping between the canonical lexical space
HZ>> and the value space.  Because 2001-03-21T24:00:00Z maps to the
HZ>> same value as 2001-03-22T00:00:00Z, I don't believe they can both
HZ>> be permitted to be canonical lexical values.

Thanks,

Henry 
[1] http://lists.w3.org/Archives/Public/xmlschema-dev/2001Mar/0111.html
------------------------------------------------------------------------
Henry Zongaro      XML Parsers development
IBM SWS Toronto Lab   Tie Line 969-6044;  Phone (905) 413-6044
mailto:zongaro@ca.ibm.com
Received on Friday, 2 November 2001 12:48:54 GMT

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