1. A person may assert a claim in a specified foreign money. If a foreign-money claim is not asserted, the claim is in United States dollars.
2. An opposing party may allege and prove that a claim, in whole or in part, is in a different money than that asserted by the claimant.
3. A person may assert a defense, setoff, recoupment, or counterclaim in any money without regard to the money of other claims.
4. The determination of the proper money of the claim is a question of law.