Packet 0x96/0x97

According to Fuzziqer's documentation, Packet 0x96 is some kind of client checksum. What it is a checksum of, I have no idea (but knowing about the checksums in PSOBB, its probably a CRC32 of something). Clients expect a reply to this packet that is of type 0x97.

Dreamcast Packet Format (Client->Server)

BytesMeaning
0x00Packet Type (0x96)
0x01Flags (0x00)
0x02-0x03Packet Size (0x0008)
0x04-0x07Checksum

Dreamcast Packet Format (Server->Client)

BytesMeaning
0x00Packet Type (0x97)
0x01Flags (Checksum Response)
0x02-0x03Packet Size (0x0004)

Checksum Responses

FlagMeaning
0Bad Checksum
1Ok

Sending the bad checksum response to the client will cause the client to overwrite portions of the character data. Specifically on PSOGC, according to chaos_ak, it clears such information as your inventory, bank, material usage, and C-Mode completion. Kayak (and Kabes) add that it clears techniques as well.