docs: public BaseField getReferencedField(int iIndex)
      {
          if (m_recordMain != null)
              return m_recordMain.getKeyArea().getField(iIndex);
          if (iIndex == 0)
              return m_fldMainFile;
          if (iIndex == 1)
              return m_fldMainFile2;
          if (iIndex == 2)
              return m_fldMainFile3;
          return null;
      }