def _get_column_info_keystring():
    """
    Define the special key name within the table_meta_data dictionary for columns.

    Define the special key name within the table_meta_data dictionary that is used to hold information on all columns (parsed from the '# TableCol' lines). Could be any string, as long as it does not clash with other meta data entries in the stats file.
    """
    return 'column_info_'
