code: def _read_etc(etc_file):
      
      etc_type = dtype([('offset', '<i'),
                        ('samplestamp', '<i'),
                        ('sample_num', '<i'),
                        ('sample_span', '<h'),
                        ('unknown', '<h')])
  
      with etc_file.open('rb') as f:
          f.seek(352)  # end of header
          etc = fromfile(f, dtype=etc_type)
  
      return etc
docs: Return information about table of content for each erd.