<!-- a document with several embedded XHTML documents -->
<outer>
    <html lang="en" xmlns='http://www.w3.org/1999/xhtml'>
    <head>
        <meta charset="UTF-8"/>
        <title>Title</title>
    </head>
    <body>

    </body>
    </html>
    <html lang="en" xmlns='http://www.w3.org/1999/xhtml'>
    <head>
        <meta charset="UTF-8"/>
        <title>Title</title>
    </head>
    <body>

    </body>
    </html>
</outer>