Mine

    /*************************************************************/
    /* Name : Anthony Alves                                      */
    /*************************************************************/

function checkForm() 
{
        var error_message;
        var temp_error;

        temp_message = surname();
        if(temp_message != "")
        {
                error_message = pageHeader(error_message);
                error_message += temp_message;
                error_message = pageFooter(error_message);
                error_window = window.open("", "errors", 'width=450, height=300');
                error_window.document.write(error_message);
                error_window.document.close();
        }


        /*window.open('error.html');*/ 
        return false;
}

function surname()
{
        var field01 = document.getElementById('field01');

        if(field01.value == "")
                return "Must have a surname."

}



     function pageHeader(content) {
       content = '<?xml version="1.0"encoding="UTF-8" ?>\n';
       content += '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"\n';
       content += '"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">\n';
       content += ' <html xmlns="http://www.w3.org/1999/xhtml">\n';
       content += '  <head>\n';
       content += '   <title>form validation</title>\n';
       content += '  </head>\n';
       content += '  <body>\n';
       content += '   <h3>Please correct the following and resubmit the form</h3>\n';
       content += '   <ul>\n';
       return content;
     }


     function pageFooter(content) {
       content += '   </ul>\n';
       content += '  </body>\n';
       content += ' </html>\n';
       return content;
     }