<?xml version="1.0"?>
<!-- Digital Item Adaptation ISO/IEC 21000-7 -->
<!-- Schema for basic schema tools -->
<schema
	version="ISO/IEC 21000-7"
	id="DIA.xsd"
	targetNamespace="urn:mpeg:mpeg21:2003:01-DIA-NS"
	xmlns="http://www.w3.org/2001/XMLSchema"
	xmlns:dia="urn:mpeg:mpeg21:2003:01-DIA-NS"
	elementFormDefault="qualified" attributeFormDefault="unqualified">

	<!-- ################################################	-->
	<!--  Definition of DIA Base Types						-->
	<!-- ################################################	-->

	<complexType name="DIABaseType" abstract="true">
		<complexContent>
			<restriction base="anyType">
				<attribute name="id" type="ID" use="optional"/>
			</restriction>
		</complexContent>
	</complexType>

	<complexType name="DIADescriptionType" abstract="true">
		<complexContent>
			<extension base="dia:DIABaseType"/>
		</complexContent>
	</complexType>

	<!-- ################################################ -->
	<!--  Definition of Description Metadata Type         -->
	<!-- ################################################ -->
	<complexType name="DescriptionMetadataType">
		<complexContent>
			<extension base="dia:DIABaseType">
				<sequence>
					<element name="ClassificationSchemeAlias" maxOccurs="unbounded">
						<complexType>
							<complexContent>
								<extension base="dia:DIABaseType">
									<attribute name="alias" type="NMTOKEN" use="required"/>
									<attribute name="href" type="anyURI" use="required"/>
								</extension>
							</complexContent>
						</complexType>
					</element>
				</sequence>
			</extension>
		</complexContent>
	</complexType>

	<!-- ################################################	-->
	<!--  Definition of DIA Root Element						-->
	<!-- ################################################	-->

	<element name="DIA">
		<complexType>
	      <sequence>
	         <element name="DescriptionMetadata" type="dia:DescriptionMetadataType"
					minOccurs="0"/>
			   <choice maxOccurs="unbounded">
				   <element name="Description" type="dia:DIADescriptionType"/>
				   <element name="Reference" type="dia:ReferenceType"/>
			   </choice>
	      </sequence>
		</complexType>
	</element>

	<element name="DIADescriptionUnit" type="dia:DIABaseType"/>

	<!-- ################################################	-->
	<!--  Definition of Reference								-->
	<!-- ################################################	-->

	<complexType name="ReferenceType">
		<attribute name="uri" type="anyURI" use="required"/>
	</complexType>

</schema>