Michael

For the benefit of everyone else the example xsd files are shown below:

Extensions.xsd:

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema targetNamespace="http://localnamespace"
elementFormDefault="qualified" xmlns="http://localnamespace"
	xmlns:main="http://mainnamespace"
xmlns:xs="http://www.w3.org/2001/XMLSchema">
	<xs:import namespace="http://mainnamespace"
schemaLocation="main.xsd" />
	<xs:element name="NewEle">
		<xs:complexType>
			<xs:sequence>
				<xs:sequence>
					<xs:element name="NewSubEle"
type="main:MyComplexType"/>
				</xs:sequence>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
</xs:schema>



Main.xsd:

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema targetNamespace="http://mainnamespace"
elementFormDefault="qualified" xmlns="http://mainnamespace"
	xmlns:mstns="http://tempuri.org/XMLSchema.xsd"
xmlns:xs="http://www.w3.org/2001/XMLSchema">
	<xs:element name="TestRootElement">
		<xs:complexType>
			<xs:sequence>
				<xs:element name="ChildElement">
					<xs:complexType>
						<xs:sequence />
					</xs:complexType>
				</xs:element>
			</xs:sequence>
			<xs:attribute ref="testatt"></xs:attribute>
		</xs:complexType>
	</xs:element>
	<xs:element name="TestGlobalEle">
		<xs:complexType>
			<xs:sequence />
		</xs:complexType>
	</xs:element>
	<xs:complexType name="MyComplexType">
	</xs:complexType>
	<xs:attribute name="testatt"></xs:attribute>
</xs:schema>



Plug-in.xsd:

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema targetNamespace="http://mainnamespace"
elementFormDefault="qualified" xmlns="http://mainnamespace"
	xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:import namespace="http://localnamespace"
schemaLocation="Extensions.xsd"/>
<xs:redefine schemaLocation="Main.xsd">
	<xs:complexType name="MyComplexType">
	<xs:complexContent>
	<xs:extension base="MyComplexType">
	   <xs:sequence>
	   <xs:element name="NewRedefinedEle"></xs:element>
	   </xs:sequence>
	</xs:extension>
	</xs:complexContent>
	</xs:complexType>
</xs:redefine>

</xs:schema>



Thanks

Simon