Hello.

According to e-mail conversation you had with our support team, it turned out that you are using ASPX templates, not Portal engine. Is that correct? If so, the post is in improper category. Please note – solution of a problem may often depend on development model you are using, so it is necessary to specify it properly (Portal engine vs. ASPX templates).

In ASPX templates you can change this directly in your master page - by default is used a macro <%=DocType%> so you can add your definition instead of this.

Best Regards,
Radek Macalik