<data><xpath expr="//field[@name='sale_line_id'][1]" position="attributes">
                <attribute name="optional">show</attribute>
            </xpath>
            <xpath expr="//field[@name='sale_line_id'][2]" position="attributes">
                <attribute name="optional">show</attribute>
            </xpath>
            <xpath expr="//field[@name='quantity_percentage'][1]" position="attributes">
                <attribute name="optional">show</attribute>
            </xpath>
            <xpath expr="//field[@name='quantity_percentage'][2]" position="attributes">
                <attribute name="optional">show</attribute>
            </xpath>
        </data>