Ultima Online Protocol :: Groups
Packet # Packet Name Length Client Server Obsolete
0x39 Groups 0x0009 ?
Data Type Description
byte 0x39 The packet number.
uint player_serial? The player's serial. If this is zero, then remove target_serial from the group.
uint target_serial The target's serial.

If player_serial is zero, remove target_serial from the group.
If target_serial is the player's serial, it will show "Removed from group."

Packet Description:
Not really sure what this is for. I think it's a classical packet.