W3C home > Mailing lists > Public > xmlschema-dev@w3.org > July 2001

Re: Date

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 08 Jul 2001 17:00:39 +0100
To: Noah_Mendelsohn@lotus.com
Cc: "Jeff Rafter" <jeffrafter@definedweb.com>, vdv@dyomedea.com, xmlschema-dev@w3.org
Message-ID: <f5bpubbif6g.fsf@cogsci.ed.ac.uk>
Noah_Mendelsohn@lotus.com writes:

> Henry Thompson writes:
> >> This is just not true.  12:00:00 is not equal to 
> >> 12:00:00Z.  What _is_  true is that the various 
> >> timezone-specific ways of specifying a time
> >> _are_ equal, e.g. 12:00:00Z is equal to 13:00:00Z+1.
> I had missed the former point, but it was the latter that was the subject 
> of my note.  I think many users find it counterintuitive that 12:00:00Z == 
> 13:00:00Z+1, as many seem to think they are making a useful record of the 
> timezone in which the time was noted.  All my explanations and warnings 
> were directed to this case, sorry for having missed the distinction 
> between times with and without timezones.   I still think the decision to 
> allow timezones, but to make them insignificant in this case, is a 
> questionable call.

Right, so there was certainly a point (in London in January, I think,
possibly still at the Tech Plenary in February) when there were 25
disjoint value spaces.  But that was clearly bogus, since given our
current lexical flexibility to do this right there would have to be
24x60x2 - 1 distinct value spaces.  I don't _think_ you want to go
there.  So I'd invite you to consider again that the problem is not
with our date-time ontology, which seems about right to me, but rather
is with the common sense interpretation of ordinary lexical forms.  I
actually find it pretty surprising that your users think 12:00:00Z is
different from 13:00:00+1.  I wouldn't find it surprising _at all_ if
they thought 12:00:00BST was different from 07:00:00EDT.  Note that
it's the _latter_ which is subject to change by law, but _not_ the

  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
Received on Sunday, 8 July 2001 12:00:41 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 7 January 2015 14:55:52 UTC