[IBR-079-OM] - When Item type (BTOM-019) is 'Goods' then Item classification identifier (ibt-158) must be provided except when Invoice transaction type (BTOM-001) is 'Simplified Tax Invoice' (X1XXXXXXXXXXXXXXXXXX)
IBR-079-OMcac:InvoiceLine | cac:CreditNoteLine$isSimplified or not(cac:Item/cac:CommodityClassification/cbc:NatureCode='GS') or cac:Item/cac:CommodityClassification/cbc:ItemClassificationCode