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Re: I need help with some schema problems

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: Tue, 06 Jan 2004 15:38:47 +0000
To: "Adam van den Hoven" <AvandenHoven@cucbc.com>
Cc: <xmlschema-dev@w3.org>
Message-ID: <f5bfzetnl2w.fsf@erasmus.inf.ed.ac.uk>

I am baffled as to what's wrong with this case, but I observe that SQC
(2.2) also complains about test4, but not test1 or test2 or test3.

Ah, I see the problem -- it's the vexed "pointless occurrence"
'feature'.  Xerces and SQC are right, the rest of us (including XSV)
are wrong.  When a sequence has min and max of 1 and is embedded in
another sequence, you have to pretend it's not there, so you're
actually comparing

 (a,b,d?) with ((a|b|c)*,d?)

which is a three-versus-two comparison, which fails.  Sigh.

As mentioned by someone in the thread you started, fixing this is
_high_ on the list of planned changes for 1.1.

  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                      Half-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/
 [mail really from me _always_ has this .sig -- mail without it is forged spam]
Received on Tuesday, 6 January 2004 10:38:51 UTC

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