code: public void init(BaseField field, Record mergeTable, Record subTable, ScreenParent gridScreen)
      {
          super.init(field);
          m_gridScreen = gridScreen;
          m_mergeRecord = mergeTable;
          m_subRecord = subTable;
          if (subTable != null)
          {   // Remove this listener when the file closes
              FileListener listener = new FileRemoveBOnCloseHandler(this);    // If this closes first, this will remove FileListener
              subTable.addListener(listener);   // Remove this if you close the file first
          }
      }
docs: Constructor.
  @param field The basefield owner of this listener (usually null and set on setOwner()).
  @param mergeTable The parent merge record.
  @param subTable The sub-record to add and remove from the parent merge record.
  @param gridScreen The (optional) grid screen to requery on change.