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Re: Is it legitimate to compare 2 dateTime without timezones?

From: Eric van der Vlist <vdv@dyomedea.com>
Date: Mon, 29 Oct 2001 17:00:11 +0100
Message-ID: <3BDD7D0B.1070104@dyomedea.com>
To: xmlschema-dev@w3.org
Noah_Mendelsohn@lotus.com wrote:

> Also, keep in mind that even when you use a timezone, it is a construction 
> in the lexical form that is not distinguishable separately in the value. 
> The difference between
>         1PM GMT-5
> and     6PM GMT  (I know these aren't the right lexical forms)
> is much like the difference between:
>         1E+2
> and     100.0

> in float.  The two sets of forms represent the same values, respectively, 
> and will compare equal. 

Yes, allowing to say 1PM without mentioning any timezone is like 
allowing to say 1 without specifying the order of magnitude and saying 
that it's 1E"something undetermined".

Considering that 1PM == 1PM is implying that there is an "implicit 
application timezone" common to a schema and all its instance documents. 
I am not discussing the design decision, but think that it should be 
better documented...

> I was against this design choice for date/time, as 
> I felt that users would expect timezones to be significant if supplied.  I 
> lost, and it's certainly too late to change now.  Even when timezones are 
> supplied, they cannot be seen directly in the value space. 

Yes and I think that it's a third (and different) issue!

The first two issues being this implicit timezone and the fact that 
symbolic timezones (BST, EST, PST, ...) are not directly supported.



> ------------------------------------------------------------------------
> Noah Mendelsohn                                    Voice: 1-617-693-4036
> Lotus Development Corp.                            Fax: 1-617-693-8676
> One Rogers Street
> Cambridge, MA 02142
> ------------------------------------------------------------------------

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Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
http://xsltunit.org      http://4xt.org           http://examplotron.org
Received on Monday, 29 October 2001 10:59:44 UTC

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