[ww520]

The containers are not in a contiguous memory block. To serialize it, you could write out each container as a length prefixed block with the container id, which is the 16-bit MSB of the container. The top level sorted list can be ignored, as it can be reconstructed.

To de-serialize, read each container by reading its prefix length and its container id, and then read the rest of the container by the length. The top level list is sorted by the container id. It can be reconstructed by inserting the container id with the container memory pointer into the sorted list.

[ww520]

Just to add a bit. The top level list can be appended to the end of the file as a directory of the pairs of id and the file offset of the container. In this way, the list at the end of the file can be read into memory to form a mapping of container-id to file offset, which can provide random access to the container blocks in the file.