Node
<cac:OrderReference>
<cbc:ID> </cbc:ID>
<cbc:SalesOrderID> </cbc:SalesOrderID>
</cac:OrderReference>
In Isah
PurchaseDocument.PurOrdNr
The sales order reference consists of an ID and a sales order ID. The ID is the original purchase order code; the sales order ID is the supplier's sales order code. Only the purchase order code is used.