function Left(str, n) {
        if (n <= 0)
                return "";
        else if (n > String(str).length)
                return str;
        else
                return String(str).substring(0,n);
}

if (top == self) {
  //var sPath = window.location.pathname; //Neemt geen querystring mee
  var sPath = window.location.href;
  var sPage = sPath.substring(sPath.lastIndexOf('/') + 1);
  if ( Left(sPage,3)=='con' ) location = 'index_con.asp?main='+sPage;
  if ( Left(sPage,3)=='std' ) location = 'index_con.asp?main='+sPage;
  if ( Left(sPage,3)=='pro' ) location = 'index_pro.asp?main='+sPage;
}