The actual save data is raw binary information, with a save header at the beginning of initial blocks. This can be compared to the directory information to validate the directory against the save. The second through fourth frames contain icons. This results in a 16 by 16 bitmapped icon. The rest of the frames in the initial block contain save data formatted in any way desired by the game's developers.
Any additional blocks consist entirely of such arbitrarily formatted data.
There are a lot of different ways to get a save from a memory card onto your PC's hard disk, and these ways sometimes involve sticking some additional information into a header at the beginning of the file. All of these headers contain a signature at the top of the file. If a signature is not known, you can rely on the memory card's raw format by searching the file for the constant ID header in frame 0 of block 0. The next 128K or less of the file should be a valid PSX memory card. Finally, we must cover the single-save format used by the Xploder and Action Replay cartridges.