Odoo-Build/snippets/purchase_requisition.view_purchase_requisition_form.replace_title.xml

<data inherit_id="purchase_requisition.view_purchase_requisition_form" priority="50">
    <xpath expr="//h1/../label" position="replace">
        <span class="o_form_label" attrs="{'invisible': [('state','not in',('draft','sent'))]}">Request for Quotation </span>
        <span class="o_form_label" attrs="{'invisible': [('state','in',('draft','sent'))]}">Purchase Order </span>
    </xpath>
</data>