function resort(sortBy, op, shipid) {
  var docAction = document.SortForm.action;
  var queryString = "";
  if (docAction.indexOf('?') == -1) {
    queryString = "?sort=" + sortBy;
  } else {    
    queryString = "&sort=" + sortBy;
  }
  if (op != "") queryString += "&op=" + op;
  if (shipid != "") queryString += "&shipid=" + shipid;
  document.SortForm.action += queryString;
  document.SortForm.action += "#fd";
  document.SortForm.submit();
}