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Re: A question on "Restriction"

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 15 Dec 2000 09:46:41 +0000
To: Yimin Zhu <yzhu@citadon.com>
Cc: "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
Message-ID: <f5b4s06j9tq.fsf@cogsci.ed.ac.uk>
Yimin Zhu <yzhu@citadon.com> writes:

> If I have a complextType A containing two sub elements B and C.
> 
> <complexType name="A">
> 	<complexContent>
> 		<element name="B" type="string"/>
> 		<element name="C" type="string"/>
> 	</complexContent>
> </ComplexType>

Not valid as written, should be

 <complexType name="A">
  <element name="B" type="string"/>
  <element name="C" type="string"/>
 </complexType>

> Now I wish to define an element E, which is inherited from A. Also, E can
> only have B in its content model. Can I do it by using restriction as
> following?

> <element name="E">
> 	<complexType>
> 			<xsd:complexContent>
> 				<xsd:restriction base="A">
> 					<xsd:all>
> 						<xsd:element name="B"
> type="xsd:string"/>
> 					</xsd:all>
> 				</xsd:restriction>
> 			</xsd:complexContent>
> 	</complexType>
> </element>

Again, typos corrected, and assume prefix 'my' for targetNamespace:

<element name="E">
  <complexType>
   <complexContent>
     <restriction base="my:A">
       <all>
         <element name="B" type="string"/>
       </all>
      </restriction>
   </complexContent>
  </complexType>
</element>

No, this is not valid.  Restriction can only eliminate optional parts
of content models, and the 'C' element in the 'A' type was not
optional.

ht
-- 
  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 Friday, 15 December 2000 04:46:44 GMT

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