1<?xml version="1.0"?> 2<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 3 <xsd:element name= "contact" type="ContactType"/> 4 <xsd:complexType name="ContactType"> 5 <xsd:choice minOccurs="1" maxOccurs="2"> 6 <xsd:element name="customer" type="xsd:string" /> 7 <xsd:element name="comment" type="xsd:string" minOccurs="0"/> 8 </xsd:choice> 9 </xsd:complexType> 10</xsd:schema> 11