Text (4th/5th/6th/7th/8th+errata): ~this~ deals 4 damage divided as you choose among any number of target creatures and/or players. [Oracle 2009/07/08]
You cannot do fractional points of damage. [Duelist Magazine #2, Page 9]
You cannot choose to do zero damage to a target. [WotC Rules Team 1995/07/19]
You cannot choose to have zero targets. You must choose between 1 and 4 targets. [Jordan 2003/05/19]
You can assign damage to multiple targets and are not forced to assign the same amount of damage to each target (like you are with Fireball). [D'Angelo 1995/03/07]
No matter how much you assign to a target, it is only targeted once, and so damage is assigned once per target regardless of the amount of damage assigned to that target. [D'Angelo 1995/03/02]
