<xs:simpleType name="InvoiceFrequencyType" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:restriction base="xs:string"> <xs:enumeration value="NotSpecified" /> <xs:enumeration value="Batch" /> <xs:enumeration value="Monthly" /> <xs:enumeration value="Weekly" /> <xs:enumeration value="Quarter" /> </xs:restriction> </xs:simpleType>