[IBR-078-OM] - Item Type (BTOM-019) must be provided for each item (IBT-153) except when Invoice transaction type (BTOM-001) is 'Simplified Tax Invoice' (X1XXXXXXXXXXXXXXXXXX).
IBR-078-OMcac:InvoiceLine | cac:CreditNoteLine $isSimplified or cac:Item/cac:CommodityClassification/cbc:NatureCode