The Free On-line Dictionary of Computing (19 January 2023):

Volume Table Of Contents
VTOC

    (VTOC) /V-tock/ A special file on a disk, which
   contains a list of all the ordinary files on the disk and
   their addresses.  Also called a directory.

   The term is used mostly with large mainframe disk drives.
   Storage administrators will often refer to the VTOC to obtain
   information on the number of files stored on a disk.

   (1997-04-15)