code: public int fieldChanged(boolean bDisplayOption, int iMoveMode)
      {
          String string = this.getOwner().toString();
          if (Utility.isNumeric(string))
          {
              Task task = null;
              if (this.getOwner() != null)
                  if (this.getOwner().getRecord() != null)
                      if (this.getOwner().getRecord().getRecordOwner() != null)
                          task = this.getOwner().getRecord().getRecordOwner().getTask();
              if (task == null)
                  task = BaseApplet.getSharedInstance();
              return task.setLastError("Must be non-numeric");
          }
          return super.fieldChanged(bDisplayOption, iMoveMode);
      }
docs: Field must be non-numeric.