The game allows groups to be formed of characters of any level, but the XP,
equipment, and money from any kill are only shared with characters not more
than three levels below the highest level character involved in the kill.

Any equipment or money, no matter how they are obtained, cannot be used by
someone more than 5 levels below the person who originally touches it.

There are two reasons for these restrictions:

- Character association: This involves the passing of equipment, money, prep
  spells, or help in combat from a person's high level character to his low
  level character in order to speed up the process of gaining XP.  Often
  this occurs in trade where one person will help his friend's low-level
  character in return for his friend helping his.  This gives an unfair
  advantage to the lower level character.

- Reduced dependence on powerful players: New players who don't know their
  way around the game are often treated by others to equipment and
  money that that the new player has no idea how to obtain.  When these
  items come from a character around their level, they often serve as a
  welcome introduction to what the game has to offer.

  But if new players are given items from much higher-level zones, this
  negates the reward for exploring, as what they have is much better than
  anything they could find themselves at their level.  Worse yet, they are
  often afraid to do anything dangerous for fear of losing equipment that
  they don't know how to replace.

A solution to both of these problems is less "help" by high levels in the
form of equipment, money, and XP.  The game enforces a cutoff at a
difference of three levels to encourage this.