In the <%@ Page %> directive, both the Culture and UICulture attributes are set to the value auto:en-US.
The culture name that appears after the colon enables you to specify a default culture when a language preference cannot be detected from the browser.
<%@ Page Language="C#" Culture="auto:en-US" UICulture="auto:en-US"%>
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
Select Culture Auto