ROM Hack [request] first 4 mystery bytes in save data file

[bunny_gg]

I just exported save data of Project X zone (US) and I found the structure of save data quite clear: one part for weapon (0/1 bitmap), one part for item (quantity bitmap) and one part for characters ( exp, equipment, ...). It is easy to modify these but it displays save data corrupted after save data file being imported.
I found first 4 bytes always changing in different save data files but I don't know the rule of how to generate them (exchanging two bytes in save data file doesn't work). Anyone has clue about these 4 bytes?

Always failed to upload save data file and screenprint. Let me try again.

I attach two save data here for reference. Difference is that I just unequipped weapon of one character in the second data and of course, timestamp is different.

Spoiler: save data 1

8A B0 B7 E3 00 01 00 00 F2 78 E0 02 00 00 00 20 11 01 0C 00 20 8F 07 2E 00 00 00 00 12 11 C0 80 0F FE 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FE BF 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 BB 3B 03 00 B2 8A 1F 00 6D 00 00 00 60 00 00 00 12 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 64 00 00 00 64 00 00 00 64 00 00 00 00 00 00 00 00 01 00 00 75 00 00 06 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 00 01 01 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 10 0B 00 00 0E 02 00 00 00 02 00 00 00 00 00 00 02 01 00 00 00 00 00 00 0C 03 00 00 04 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 11 09 00 00 07 02 00 00 01 04 00 00 00 00 00 00 01 00 00 00 00 00 00 00 0D 00 00 00 09 00 00 00 0C 04 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 B6 19 00 00 02 08 53 00 1D 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 BB 1B 00 00 04 02 40 00 60 1A 00 00 1F 0C 00 00 F2 1C 00 00 0D 07 48 00 17 1D 00 00 21 04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 C7 19 00 00 0B 12 44 00 A7 1A 00 00 09 0A 00 00 85 1D 00 00 01 00 00 00 73 18 00 00 06 05 00 00 00 00 00 00 00 00 00 00 37 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 D5 1B 00 00 0A 01 3D 00 45 1B 00 00 07 1F 00 00 CB 17 00 00 05 09 00 00 00 00 00 00 00 00 00 00 50 1B 00 00 08 0B 52 00 7A 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 0C 15 0E 06 04 17 19 05 0B 16 0D 07 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Spoiler: save data two

05 0F 3F 0E 00 01 00 00 F2 78 E0 02 00 00 00 20 11 01 0C 00 20 8F 07 2E 00 00 00 00 12 11 C0 80 0F FE 0F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FE BF 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 BB 3B 03 00 2F 29 21 00 6D 00 00 00 60 00 00 00 12 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 64 00 00 00 64 00 00 00 64 00 00 00 00 00 00 00 00 01 00 00 75 00 00 06 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 00 01 01 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 10 0B 00 00 0E 02 00 00 00 02 00 00 00 00 00 00 02 01 00 00 00 00 00 00 0C 03 00 00 04 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 11 09 00 00 07 02 00 00 01 04 00 00 00 00 00 00 01 00 00 00 00 00 00 00 0D 00 00 00 09 00 00 00 0C 04 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 B6 19 00 00 02 08 53 00 1D 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 BB 1B 00 00 04 02 40 00 60 1A 00 00 1F 0C 00 00 F2 1C 00 00 0D 07 48 00 17 1D 00 00 21 04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 C7 19 00 00 0B 12 44 00 A7 1A 00 00 09 0A 00 00 85 1D 00 00 00 00 00 00 73 18 00 00 06 05 00 00 00 00 00 00 00 00 00 00 37 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 D5 1B 00 00 0A 01 3D 00 45 1B 00 00 07 1F 00 00 CB 17 00 00 05 09 00 00 00 00 00 00 00 00 00 00 50 1B 00 00 08 0B 52 00 7A 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 0C 15 0E 06 04 17 19 05 0B 16 0D 07 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

 

[MissingNO123]

Probably a checksum. You'd have to figure out how the game calculates it in order to generate your own.

EDIT: It may also be the secure NAND value, which SVDT can get around.

 

[bunny_gg]

Probably a checksum. You'd have to figure out how the game calculates it in order to generate your own.

EDIT: It may also be the secure NAND value, which SVDT can get around.

the question is just about how to calculate...

I just used SVDT to export and import the sav. I know SVDT can fix secure NAND problem but it doesn't work for this one.
Another clue is that SVDT goes into debug mode with this game (same with animal crossing - new leaf), so I don't know if secure NAND step is skipped in this mode.I checked it is different. This game seems have no secure NAND.