trytond-stock_product_category_location/message.xml

<?xml version="1.0"?>
<!-- The COPYRIGHT file at the top level of this repository contains the full
     copyright notices and license terms. -->
<tryton>
    <data grouped="1">
		<!-- stock.product.category.location -->
        <record model="ir.message" id="msg_category_location_unique_key">
            <field name="text">Category and location must be unique.</field>
        </record>
    </data>
</tryton>