<!DOCTYPE html>
<html>
    <head>
        <title>menclose with empty and invalid notation attribute</title>
    </head>
    <body>
        <p>
            <math>
                <mtable>
                    <mtr><mtd><menclose notation=""><mspace width="100px" height="50px" mathbackground="red"/></menclose></mtd></mtr>
                    <mtr><mtd><menclose notation="triangle"><mspace width="100px" height="50px" mathbackground="red"/></menclose></mtd></mtr>
                </mtable>
            </math>
        </p>
    </body>
</html>