Odoo-Build/snippets/stock.report_delivery_document.set_customer_reference.xml

<data inherit_id="stock.report_delivery_document" priority="50">
    <xpath expr="//t[@t-set='address']" position="before">
        <t t-set="information_block">
            <span>
                <strong>Kundennummer: </strong>
            </span>
            <span t-esc="partner.ref"/>
            <br/>
            <br/>
        </t>
    </xpath>
</data>