code: public void addMainKeyBehavior()
      {   // Add the read keyed listener to all unique keys with one field
          Record record = this.getMainRecord();
          if (record == null)
              return;
          int keyCount = record.getKeyAreaCount();
          for (int keyNumber = DBConstants.MAIN_KEY_AREA; keyNumber < keyCount + DBConstants.MAIN_KEY_AREA; keyNumber++)
          {
              KeyArea keyAreaInfo = record.getKeyArea(keyNumber);
              if (((keyAreaInfo.getUniqueKeyCode() == DBConstants.UNIQUE)
                  || (keyAreaInfo.getUniqueKeyCode() == DBConstants.SECONDARY_KEY))
                  & (keyAreaInfo.getKeyFields() == 1))
              {
                  BaseField mainField = keyAreaInfo.getField(DBConstants.MAIN_KEY_FIELD);
                  MainFieldHandler readKeyed = new MainFieldHandler(record.getKeyArea(keyNumber).getKeyName());
                  mainField.addListener(readKeyed);
              }
          }
      }
docs: Add the read-main-key listener.