0223

Size:32
Command:16 Channel:8 0:8
0:32
0:32
0:32
0:32
0:32
TypeID:32
GID:32
0:32
0:32
AuthGID:32
AuthKey:32
(following is an optional part when a message must be shown)
_UnknownA:32
0:32
0:16 Length:16
Message:N

Size: 52
Channel: 3
TypeID: 00000f00
GID: the temporary one
AuthGID: the real account GID; 0 if something went wrong
AuthKey: random
(then the optional part)
_UnknownA: seems to be 3 for errors, but 0 is also found when the supplemental asks about free course
Length: Size / 2 + 2; to include the \0 at the end
Message: variable size

0:16 before Length is probably the same thing as MOTD: pages.