As the TCFS dataset grows, we need more efficient methods of organizing and indexing the information. It is currently impractical to store the entire contents of the ITS backup tapes on-line, so we need some way to avoid having to shuffle around dozens of tapes whenever we are looking for some particular old data. The table of contents is designed to tackle just this problem.
This portion of the system isn't designed to be as robust over the ages as the TCFS format itself, and is expected to become obsolete at the same rate as any other piece of software. The design goal for this phase was to provide us with an efficient means of tracking the files in our TCFS archives now, not 30 years from now; we presume that superior means of cataloging files will surface as storage and processing power become ever cheaper. The table of contents was also designed to conserve space where it could.