Much like a website cookie, simply stores some arbitrary string to a 'cookie jar' to save preferences et al. which can be retrieved later by the server.

Not used because it was quickly discovered that storing preferences produces less problems and were faster by storing them server-side, associating them with the account. It is somewhat curious that these packet IDs are close to SID_PROFILE/SID_WRITEPROFILE (0x26 & 0x27).

Found at: battle!190216FBh and battle!1901D660h, respectively.