1<?xml version="1.0" encoding="utf-8"?> 2<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> 3 <xs:element name="catalog"> 4 <xs:complexType> 5 <xs:sequence> 6 <xs:element ref="journal" minOccurs="0" maxOccurs="unbounded"/> 7 </xs:sequence> 8 <xs:attribute name="title" type="xs:string"/> 9 <xs:attribute name="publisher" type="xs:string"/> 10 </xs:complexType> 11 </xs:element> 12 <xs:element name="journal"> 13 <xs:complexType> 14 <xs:sequence> 15 <xs:element ref="article" minOccurs="0" maxOccurs="unbounded"/> 16 </xs:sequence> 17 <xs:attribute name="date" type="xs:string"/> 18 </xs:complexType> 19 </xs:element> 20 <xs:element name="article"> 21 <xs:complexType> 22 <xs:sequence> 23 <xs:element name="title" type="xs:string" minOccurs="1" default="Schema Validation"/> 24 <xs:element ref="author" minOccurs="0" maxOccurs="unbounded"/> 25 </xs:sequence> 26 </xs:complexType> 27 </xs:element> 28 <xs:element name="author" type="xs:string"/> 29</xs:schema> 30 31