These variables are replaced on execution (i.e. when the item is used by a player):

• ${p}: The name of the player using the item (from now on, the user)
• ${p.x}: The X coordinate of the user's location.
• ${p.y}: The Y coordinate of the user's location.
• ${p.z}: The Z coordinate of the user's location.
• ${p.w}: The name of the world the user is on.