function form_validate_set_party_signup(num_shifts) {
  var result = "";
  
  //Check for unique names
  var i; var j;
  for (i = 1; i <= num_shifts; i++) {
    var field = document.getElementsByName("shift_name_" + i);
    if (field[0].value != "") {
      for (j = 1; j < i; j++) {
        var temp = document.getElementsByName("shift_name_" + j);
        if (field[0].value == temp[0].value) {
          break;
        }
      }
      if (i != j) {
        result += "Invalid shift name for shift " + i + ": name not unique.\n";
      }
    }
  }
  
  //Check for dates
  //***NOT DONE
  
  if (result != "") alert(result);
  return result == "";
}