<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="list"> <xs:complexType> <xs:sequence> <xs:element name="item" maxOccurs="unbounded" minOccurs="0"> <xs:complexType> <xs:sequence> <xs:element name="options" maxOccurs="unbounded" minOccurs="0"> <xs:complexType> <xs:attribute type="xs:byte" name="level" use="required" /> <xs:attribute type="xs:integer" name="option1" use="required" /> <xs:attribute type="xs:integer" name="option2" use="optional" /> <xs:attribute type="xs:integer" name="option3" use="optional" /> </xs:complexType> </xs:element> </xs:sequence> <xs:attribute type="xs:integer" name="id" use="required" /> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema>