<xs:element name="terminology"><xs:complexType><xs:sequence><xs:element ref="terminologyAssociation" minOccurs="0" maxOccurs="unbounded"/><xs:element ref="codeSystem" minOccurs="0" maxOccurs="unbounded"/><xs:element ref="valueSet" minOccurs="0" maxOccurs="unbounded"/><xs:element name="conceptMap" type="ConceptMapType" minOccurs="0" maxOccurs="unbounded"/></xs:sequence></xs:complexType><!-- Cannot have two valueSets carrying the same id and effectiveDate --><xs:unique name="valueset-idversion-unique"><xs:selector xpath="valueSet"/><xs:field xpath="@id"/><xs:field xpath="@effectiveDate"/></xs:unique><xs:unique name="valueset-ref-unique"><xs:selector xpath="valueSet"/><xs:field xpath="@ref"/></xs:unique><!-- Cannot have two codeSystems carrying the same id and effectiveDate --><xs:unique name="codesystem-idversion-unique"><xs:selector xpath="codeSystem"/><xs:field xpath="@id"/><xs:field xpath="@effectiveDate"/></xs:unique><xs:unique name="codesystem-ref-unique"><xs:selector xpath="codeSystem"/><xs:field xpath="@ref"/></xs:unique></xs:element>