<?page [id="..."] [title="..."] [style="..."] [language="xul/html"] [zscriptLanguage="Java"]?>

It describes attributes of a page.

Note: You can place the page directive in any location of a XML document, but the language attribute is meaningful only if the directive is located at the topmost level, i.e., at the the same level as the root element.

For more available options and descriptions, refer to the Developer's Reference.