[xml-dev] Extensible schemas and xs:any

Hi all,

I am having trouble making an XML schema extensible through use of 
"xs:any".

What I want is a main schema that has an element that is allowed to
have a sequence of any child nodes. To do this I defined a
global type that has an xs:any content model (is that the
right way to say this?). The document element then has a child
element of this type. (see Main.xsd below)

Then I would like to have a 'sub' schema that xs:imports the main
schema - and in this sub schema I over-ride the "Stuff" element
from  the main schema and specify that the Stuff element must have
certain elements.
(see Sub.xsd below)

Finally - if I construct an instance document that specifies the
location of both schemas - and includes the Stuff element with
child elements as declared in the Sub schema - I try to validate
this hybrid document against both schemas. (see Stuff.xml below)

I've included below the 2 schemas and a sample instance. XSV
complaigns about the way I've done it (I've included a bit of the
error message below). XSV says it "can't find a type for
wildcard-matching element <qualified name of element in Sub schema>"

Is what I'm trying to do possible? If so what am I doing wrong?
If it's not possible - can anyone suggest a way to achieve the
same result - that is to be able to define elements of a schema
that can take any content - but that can be restricted by other
schemas?

Thanks

Murray

################### Main.xsd  ########################
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://redcone.gbst.com/Main"
     xmlns:main="http://redcone.gbst.com/Main"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     elementFormDefault="qualified" attributeFormDefault="qualified">

     <xs:complexType name="StuffType">
	<xs:sequence>
	    <xs:any maxOccurs="unbounded"/>
	</xs:sequence>
	</xs:complexType>
	
	<xs:element name="Things">
	   <xs:complexType>
		<xs:sequence>
		    <xs:element name="Thing" type="xs:string"/>
		    <xs:element name="Stuff" type="main:StuffType"/>
		</xs:sequence>
	    </xs:complexType>
	</xs:element>
</xs:schema>

################### Sub.xsd  ########################
<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XML Spy v4.0.1 U (http://www.xmlspy.com) by Nick 
Russell (QUT) -->
<xs:schema targetNamespace="http://redcone.gbst.com/Sub"
     xmlns:main="http://redcone.gbst.com/Main"
     xmlns:sub="http://redcone.gbst.com/Sub"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     elementFormDefault="qualified" attributeFormDefault="qualified">

     <xs:import namespace="http://redcone.gbst.com/Main"
         schemaLocation="Main.xsd"/>

     <!-- This is the Document Element -->
     <xs:element  name="Stuff" type="sub:MyStuffType"/>

     <xs:complexType name="MyStuffType">
	<xs:complexContent>
	    <xs:restriction base="main:StuffType">
		<xs:sequence>
		    <xs:element name="MyStuffA" type="xs:string"/>
		    <xs:element name="MyStuffB" type="xs:string"/>
		</xs:sequence>
	    </xs:restriction >
	</xs:complexContent>
     </xs:complexType>
</xs:schema>

################### Stuff.xml  ########################
<?xml version="1.0" encoding="UTF-8"?>
<!--Sample XML file generated by XML Spy v4.3 U (http://www.xmlspy.com)-->
<main:Things
	xmlns:main="http://redcone.gbst.com/Main"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 	
	xmlns:sub="http://redcone.gbst.com/Sub"
	xsi:schemaLocation=
		"http://redcone.gbst.com/Main
		Main.xsd
		http://redcone.gbst.com/Sub
		Sub.xsd">
	<main:Thing>String</main:Thing>
	<main:Stuff>
		<sub:MyStuffA>blah</sub:MyStuffA>
		<sub:MyStuffB>blad</sub:MyStuffB>
	</main:Stuff>
</main:Things>


############ fragment of XSV error msg  ##################
<invalid char='3' code='src-resolve' line='14'
resource='file:/f:/murray/sec_lending/schemas/Stuff.xml'>
can't find a type for wildcard-matching element
{http://redcone.gbst.com/Sub}:MyStuffA</invalid>