Substitution groups

[Ben Ryan <b_ryan@c-elect.co.uk>]

Hi,
	I am trying to a schema where I want to model addresses that can handle
both UK and US style codes e.g. postcode and zip code. I wanted to use
substitution groups as follows:

<xsd:element name="code" type="astring" abstract="true">
</xsd:element>

<xsd:element name="postcode" type="astring" substitutionGroup="code">
</xsd:element>

<xsd:element name="zip" type="astring" substitutionGroup="code">
</xsd:element>

where the complex type astring is defined as follows:

<xsd:complexType name="astring" mixed="true">
  <xsd:sequence minOccurs="0" maxOccurs="unbounded">
    <xsd:any namespace="##other"/>
  </xsd:sequence>
</xsd:complexType>

Using XMLSpy this validates OK, but using the IBM Schema Quality Checker
I get the following errors:

SUBSTITUTION GROUP ERROR : the type of the element declaration,element
postcode, is not compatible with the type of its substitution group
head.  
 
SUBSTITUTION GROUP ERROR : the type of the element declaration,element
zip, is not compatible with the type of its substitution group head.  

Can anyone explain this as I assumed :) that as they all are the same
type there should be no problem.


Thanks,

Ben

-- 
***************************
Dr Benjamin Ryan
Senior Technical Consultant
C-Elect
Tel: +(44) 1484 517077
Fax: +(44) 1484 517068
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