Billing Reference id

XML and business rules
2

XML examples are available in the SDK.
You can download the SDK in Sandbox. After opening it, go to Data → Samples.

Example of tag:

<cac:BillingReference>
    <cac:InvoiceDocumentReference>
        <cbc:ID>SME00002</cbc:ID>
    </cac:InvoiceDocumentReference>
</cac:BillingReference>

Example details can be found also in the data dictionary, Term ID BT-25.