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RE: Year 0000

From: <zongaro@ca.ibm.com>
Date: Mon, 27 Aug 2001 09:25:02 -0400
To: "Andrew Layman" <andrewl@microsoft.com>
Cc: lmartin@ca.ibm.com, "Ashok Malhotra" <ashokma@microsoft.com>, <www-xml-schema-comments@w3.org>, <w3-xml-schema-wg@w3.org>
Message-ID: <OFBFF256F7.EFF09444-ON85256AB5.0045D2B2@torolab.ibm.com>
Hi Andrew,

     Perhaps I was a bit imprecise in saying that the year 0000 in ISO 
8601 is what is commonly called 1 BCE.  The year 1 BCE is a year in the 
Julian calendar, whereas ISO 8601 treats the Gregorian calendar as if it 
existed prior to 1582-10-15, and extends it indefinitely back in time.  So 
0000 in ISO 8601 and 1 BCE overlap to a great extent, but not necessarily 
completely.

     1582-10-05 is the day after 1582-10-04, and 1582-10-14 is the day 
before 1582-10-15 in ISO 8601.

Thanks,

Henry
------------------------------------------------------------------------
Henry Zongaro      XML Parsers development
IBM SWS Toronto Lab   Tie Line 778-6044;  Phone (416) 448-6044
mailto:zongaro@ca.ibm.com

Please respond to "Andrew Layman" <andrewl@microsoft.com> 
To:     Lisa Martin/Toronto/IBM@IBMCA, "Ashok Malhotra" <ashokma@microsoft.com>
cc:     Henry Zongaro/Toronto/IBM@IBMCA, <www-xml-schema-comments@w3.org>, 
<w3-xml-schema-wg@w3.org> 
Subject:        RE: Year 0000


In that case, is 1582-10-05 a valid ISO 8601 date?  What day follows
1582-10-04?  What day precedes 1582-10-15?  Are the answers to these
questions consistent with the assumption that year 0000 is 1 BCE?

-----Original Message-----
From: lmartin@ca.ibm.com [mailto:lmartin@ca.ibm.com] 
Sent: Friday, August 10, 2001 2:08 PM
To: Ashok Malhotra
Cc: zongaro@ca.ibm.com; www-xml-schema-comments@w3.org;
w3-xml-schema-wg@w3.org
Subject: RE: Year 0000


Yes, I'll add it to our Issues list.
Lisa.


"Ashok Malhotra" <ashokma@microsoft.com> on 08/10/2001 04:11:14 PM

Please respond to "Ashok Malhotra" <ashokma@microsoft.com>

To:   Henry Zongaro/Toronto/IBM@IBMCA
cc:   <www-xml-schema-comments@w3.org>, <w3-xml-schema-wg@w3.org>, Lisa
      Martin/Toronto/IBM@IBMCA
Subject:  RE: Year 0000


Yes, I came to the same conclusion after rereading the 2000 version of
ISO 8601. I think we need to consider this as a possible errata item.
Lisa, can you please add to the errata list.



All the best, Ashok
===========================================================

     -----Original Message-----
     From: zongaro@ca.ibm.com [mailto:zongaro@ca.ibm.com]
     Sent: Friday, August 10, 2001 1:01 PM
     To: Ashok Malhotra
     Cc: www-xml-schema-comments@w3.org; w3-xml-schema-wg@w3.org;
     lmartin@ca.ibm.com
     Subject: RE: Year 0000



     Hi Ashok,

          Although ISO 8601:2000 isn't entirely clear on the point, it
does
     say that the year numbers are contiguous.  I take that to mean that
     0000 is the year before 0001, and -0001 is the year before that.
That
     would mean 0000 is what is usually referred to as 1 BC (or 1 BCE)
and
     -0001 is 2 BC (or 2 BCE).

          If my understanding is correct, that means the years that are
     commonly called 1BC (0000) and 5BC (-0004) are leap years in the
     proleptic Gregorian calendar, but 4BC (-0003) is not.

     Thanks,

     Henry
 
------------------------------------------------------------------------

     Henry Zongaro      XML Parsers development
     IBM SWS Toronto Lab   Tie Line 778-6044;  Phone (416) 448-6044
     mailto:zongaro@ca.ibm.com


     Please respond to "Ashok Malhotra" <ashokma@microsoft.com>


     To:        Henry Zongaro/Toronto/IBM@IBMCA,
     <www-xml-schema-comments@w3.org>
     cc:        <w3-xml-schema-wg@w3.org>, Lisa Martin/Toronto/IBM@IBMCA
     Subject:        RE: Year 0000


     I found additional confirmation that the 2000 version of ISO 8601
     does,
     indeed, allow the year 0000.  I don't know what it maps to in terms
on
     AD and BC because AD 1 == 0001 and BC 1 == -0001.  Should we
discuss
     as
     a possible errata item.
     Ashok

                     -----Original Message-----
                     From: zongaro@ca.ibm.com
                     Sent: Thu 8/9/2001 2:02 PM
                     To: www-xml-schema-comments@w3.org
                     Cc:
                     Subject: Year 0000




                     Hello,

                          I just saw a copy of ISO 8601:2000.  I was
     surprised to
     discover that it defines 0000 to be a valid year, unlike the
     specification of dateTime in the "XML Schema:  Datatypes"
     recommendation
     [1].  I gather that in ISO 8601:2000, the year 0000 is roughly
     equivalent to what people usually refer to as 1BC, and is a leap
year.

                          Should dateTime follow ISO 8601:2000 in this
     respect?

                     Thanks,

                     Henry
                     [1]
     http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#dateTime

 
------------------------------------------------------------------------

                     Henry Zongaro      XML Parsers development
                     IBM SWS Toronto Lab   Tie Line 778-6044;  Phone
(416)
     448-6044
                     mailto:zongaro@ca.ibm.com
Received on Monday, 27 August 2001 09:24:53 GMT

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