data.xml

<?xml version="1.0" encoding="utf-8"?>
<!--Copyright 2014-2016 Ivan Yelizariev <https://it-projects.info/team/yelizariev>
    Copyright 2015 Alexis de Lattre <https://github.com/alexis-via>
    Copyright 2016 Stanislav Krotov <https://it-projects.info/team/ufaks>
    License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html). -->

<odoo>

        <template id="assets" inherit_id="point_of_sale.assets">
            <xpath expr="." position="inside">
                <script type="text/javascript" src="/pos_debt_notebook/static/src/js/pos.js"></script>
                <link rel="stylesheet" href="/pos_debt_notebook/static/src/css/pos.css" id="pos_debt_notebook-stylesheet"/>
            </xpath>
        </template>

        <template id="demo_assets_backend" inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                <script type="text/javascript" src="/pos_debt_notebook/static/src/js/test_pos_debt.js"></script>
            </xpath>
        </template>

</odoo>