the unpacking manifest is a structure defined in terms of bytes.
the exe's manifest offset is set to point to the beginning of this structure.

bytes		   content
-----              -------
0 => 3		   number of chunks in the TOC
4 => 4+N-1	   first manifest item, with length N
4+N => 4+N+M-1	   second item, with length M
4+N+M =>...etc.

each bundle chunk has a structure:

bytes		   content
-----              -------
0 => 3		   size of the data component of the chunk 
4 => 4+S-1	   the file system target location for this chunk, as a zero
		   terminated string (of length S).  this string comes from the
		   target defined in the packing manifest.

then the data starts after the end of the TOC; each chunk occupies the space
declared for it in the manifest.