Use the InvoiceNote element to model this information.

More information is provided in the Invoice Notes topic.

You can also model this information at the Document level, as explained in the VRBL: Invoice Note topic.

Example

<Invoice>
    <!-- code omitted for clarity -->
    <cac:InvoiceLine>
        <!-- code omitted for clarity -->
        <cbc:Note>New article number 12345</cbc:Note>
        <!-- code omitted for clarity -->
    </cac:InvoiceLine>
</Invoice>