Use the BuyersItemIdentification subelement of the InvoiceLine element to model this information.

Element

Element	Description
`Invoice/InvoiceLine/BuyersItemIdentification/ID`	Specify the ID provided by the Buyer.

Example

<Invoice>
    <!-- code omitted for clarity -->
    <cac:InvoiceLine>
        <!-- code omitted for clarity -->
        <cac:BuyersItemIdentification>
            <cbc:ID>BY-123455</cbc:ID>
        </cac:BuyersItemIdentification>
        <!-- code omitted for clarity -->
    </cac:InvoiceLine>
</Invoice>