code: public void fieldsToData(Rec record) throws DBException
      {
          try   {
              int iFieldTypes = BaseBuffer.PHYSICAL_FIELDS;
              if (!((Record)record).isAllSelected())
                  iFieldTypes = BaseBuffer.DATA_FIELDS;   //SELECTED_FIELDS; (Selected and physical)
              m_dataSource = new VectorBuffer(null, iFieldTypes);   //x new StringBuff();
              ((BaseBuffer)m_dataSource).fieldsToBuffer((FieldList)record);
          } catch (Exception ex) {
              throw DatabaseException.toDatabaseException(ex);
          }
      }
docs: Move all the fields to the output buffer.
  In this implementation, create a new VectorBuffer and move the fielddata to it.
  @exception DBException File exception.