by providing the `lang` attribute on the HTML element (e.g., `<html lang="en">`)
* **Or**, if serving an XML document only (ie. using a MIME type, such as application/xhtml+xml), identify the default language by providing the `xml:lang` attribute alone. The `lang` attribute is not needed (`<html xml:lang="fr" xmlns="https://www.w3.org/1999/xhtml">`)
* **Or**, if serving XHTML 1.x or polyglot pages as text/html, use both the `lang` attribute and the `xml:lang` attribute and ensure the values for both attribu