<xsd:complexType name="CM_PI"> <xsd:sequence> <xsd:element ref="CM_PI.1" minOccurs="0" maxOccurs="1" /> <xsd:element ref="CM_PI.2" minOccurs="0" maxOccurs="1" /> <xsd:element ref="CM_PI.3" minOccurs="0" maxOccurs="1" /> </xsd:sequence> </xsd:complexType>