2004-10-04 : The exchange isn’t optional. If there is a legal choice, you must make one.

2004-12-01 : Confusion in the Ranks triggers on itself entering the battlefield. If an opponent controls an enchantment, exchange Confusion in the Ranks for that enchantment.

2004-12-01 : Even though Confusion in the Ranks triggers only when an artifact, creature, or enchantment enters the battlefield, the ability can target a land if the permanent entering the battlefield is an artifact land.

2004-12-01 : The permanents are exchanged only if they’re both on the battlefield when the ability resolves.

2004-12-01 : The permanents have to share a permanent type both when the target is chosen and when the ability resolves.