Supplier order number.

recadv_Examples
 <documentReference documentType="SupplierOrder" id="24123456" date="2015-10-01" lineNo="2">
recadv_XPATH

/b24Message/receivingAdvice/package/item/documentReference[@documentType="SupplierOrder"]/@id

recadv_Sort
57
Subscribe to (Item/Line) : Supplier order number