minOccurs and maxOccurs
<?xml version="1.0"?> <name xmlns="http://www.java2s.com/name" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.java2s.com/name Schema.xsd" title="Mr."> <first>first</first> <middle>middle</middle> <last>last</last> </name> File: Schema.xsd <?xml version="1.0"?> <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:target="http://www.java2s.com/name" targetNamespace="http://www.java2s.com/name" elementFormDefault="qualified"> <group name="NameGroup"> <sequence> <element name="first" type="string" minOccurs="1" maxOccurs="unbounded" /> <element name="middle" type="string" minOccurs="0" maxOccurs="1" /> <element name="last" type="string" /> </sequence> </group> <complexType name="NameType"> <group ref="target:NameGroup" /> <attribute name="title" type="string" /> </complexType> <element name="name" type="target:NameType" /> </schema>