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Re: Ambiguous content models -- allowed or disallowed by XSDL?

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 13 Jun 2002 09:13:40 +0100
To: Ian Stokes-Rees <ijs@decisionsoft.com>
Cc: Morris Matsa <mmatsa@us.ibm.com>, xmlschema-dev@w3.org
Message-ID: <f5b660n7g0b.fsf@cogsci.ed.ac.uk>

Ian Stokes-Rees <ijs@decisionsoft.com> writes:

<snip/> -- I'll address the general question in another message.

> Perhaps I can better serve the discussion by providing the explicit
> example in question (see below).  I would say that this is an illegal
> ACM as you cannot identify from the single token "startDate" whether you
> are in theh first sequence (startDate, endDate) or the second sequence
> (startDate, duration).
> 
> Do others believe this type definition is legal or illegal?

Violates UPA, for sure.

The DTD equivalent, i.e. ((s,e)?|(s,d)?|(d,e)?) is also disallowed.

> Can anyone suggest a reasonable way to achieve the desired constraint?

Sure -- ((s,(d|e))|(d,e))?

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2002, part-time member of W3C Team
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	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
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Received on Thursday, 13 June 2002 04:13:46 GMT

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