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