<?xml version="1.0" encoding="UTF-8" ?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.tempuri.org/MainSchema" xmlns:tns="http://www.tempuri.org/MainSchema" xmlns:ns="http://www.tempuri.org/ImportedSchema" elementFormDefault="qualified" > <xs:import namespace="http://www.tempuri.org/ImportedSchema" schemaLocation="./import-455953.xsd" /> <xs:complexType name="MyMainType"> <xs:sequence> <xs:element name="MainA"> <xs:complexType> <xs:attribute name="MainID" type="xs:int"/> </xs:complexType> </xs:element> <xs:element ref="ns:AnotherElement" /> </xs:sequence> </xs:complexType> <xs:element name="MainElement" type="tns:MyMainType"> <xs:key name="MainKey" > <xs:selector xpath="tns:MainA" /> <xs:field xpath="@MainID" /> </xs:key> </xs:element> </xs:schema>