Absolute file offset of the place table (Section 7).
Byte length of the place table.
Entry i is the compressed byte length of chunk i (0 = empty).
Entry i is the absolute file offset of chunk i (meaningless when chunkLengths[i] === 0). Precomputed per Section 6.3.
Byte length of the directory itself.
The directory (Section 6): where the place table and each chunk are.