RE: Year 0000

Henry:
Your response to Andrew was not quite accurate.  ISO 8601 and XML Schema
use what is called the "prolaptic Gregorian calendar".  This means they
refer to years, months, etc as if the Gregorian calendar had been in use
since the beginning of time; specifically before 1582.  If you take this
viewpoint there is no discontinuity.
 
ISO 8601 in its usual cryptic fashion says (section 4.3.2.1 Note 2)
'Also note that the year numbers for years before the year [0001] differ
from the year numbers in the "BC/AD calendar system", where the year"1
BC" is followed by the year "1 AD"'   The Encarta article on calendars
http://encarta.msn.com/find/Concise.asp?z=1&pg=2&ti=761560321&cid=8#p8
says that "The Gregorian calendar is also called the Christian calendar
because it uses the birth of Jesus Christ as a starting date. "  So, the
BC/AD calendar, I assume from the above, uses Gregorian years.  Thus,
year [0001] corresponds to AD 1 and ... this is my interpretation ...
year [0000] corresponds to 1 BC and so on.  This is consistent if a bit
weird.
 
BTW, your notes appear in tiny font.  I assume this is some idiosyncracy
of Lotus Notes.
 
All the best, Ashok

 -----Original Message----- 
 From: zongaro@ca.ibm.com 
 Sent: Mon 8/27/2001 6:25 AM 
 To: Andrew Layman 
 Cc: lmartin@ca.ibm.com; Ashok Malhotra;
www-xml-schema-comments@w3.org; w3-xml-schema-wg@w3.org 
 Subject: RE: Year 0000
 
 

 
 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, 3 September 2001 18:34:26 UTC