static function make($type_uri, $count=1, $required=false,
                  $alias=null)
    {
        if ($alias !== null) {
            $result = Auth_OpenID_AX_checkAlias($alias);

            if (Auth_OpenID_AX::isError($result)) {
                return $result;
            }
        }

        return new Auth_OpenID_AX_AttrInfo($type_uri, $count, $required,
                                           $alias);
    }