W3C home > Mailing lists > Public > xmlschema-dev@w3.org > November 2002

Re: deterministic or ambiguous?

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 06 Nov 2002 13:33:22 +0000
To: "Nell Golding" <nell_golding@hotmail.com>
Cc: xmlschema-dev@w3.org
Message-ID: <f5bvg3aq0v1.fsf@erasmus.inf.ed.ac.uk>

"Nell Golding" <nell_golding@hotmail.com> writes:

> I woud like to know, whether I make mistakes in schema definition and
> XMLSpy doesn't notice them, or these are bugs of the other tools.
> 
> Here is a part of my schema that causes difficulties:
> 
> <xs:element name="root">
>   <xs:complexType>
>        <xs:choice>
> 	  <xs:sequence>
> 	    <xs:element name="Ack_Nack" type="xs:string" fixed="ACK">
> 	       <xs:annotation>
> 		 <xs:documentation>Acknowledgement</xs:documentation>
> 		</xs:annotation>
> 	    </xs:element>
> 	    <xs:element name="Reason_Nack" type="leer"/>
> 	  </xs:sequence>
> 	  <xs:sequence>
> 	    <xs:element name="Ack_Nack" type="xs:string" fixed="NACK">
> 		<xs:annotation>
>                   <xs:documentation>Rejection</xs:documentation>
> 		</xs:annotation>
> 	    </xs:element>
> 	    <xs:element name="Reason _Nack" type="Explanation_of_Nack"
> 	    maxOccurs="unbounded">
> 
> 		<xs:annotation>
>                   <xs:documentation>Explanation to the rejection of
>                   the Templates</xs:documentation>
> 
> 		</xs:annotation>
> 	    </xs:element>
> 	 </xs:sequence>
>       </xs:choice>
>    </xs:complexType>
> </xs:element>

The above content model violates the Unique Particle Attribution
constraint alright -- no way for parser to tell which Ack_Nack element
to try to validate with.  The DTD equivalent would be

   ((A_N,R_N)|(A_N,R_N))

which XML 1.0 would reject.

You're essentially trying to get a co-occurence constraint here, and
W3C XML Schema version 1.0 does not support them -- sorry.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2002, 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/
 [mail really from me _always_ has this .sig -- mail without it is forged spam]
Received on Wednesday, 6 November 2002 08:33:25 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 11 January 2011 00:14:35 GMT