pos_validate_client/templates.xml

<openerp>
    <data>
       <template id="pos_client" name="pos client" inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                <script type="text/javascript" src="/pos_validate_client/static/src/js/pos_client.js"></script>
            </xpath>
        </template>

        <record id="view_pos_customer_form" model="ir.ui.view">
        	<field name="name">pos.customer.form.view</field>
        	<field name="model">pos.config</field>
        	<field name="inherit_id" ref="point_of_sale.view_pos_config_form"/>
        	<field name="arch" type="xml">
        		<xpath expr="//field[@name='iface_invoicing']" position="after">
        			<field name="is_customer_mandatory" id="is_mendatory"/>
        		</xpath>
        	</field>
        </record>

    </data>
</openerp>