Avoidance takes effect retroactively.
This Article states the rule that avoidance takes effect retroactively. In other words, the contract is considered never to have existed. In the case of a partial avoidance under Article 3.2.13 the rule applies only to the avoided part of the contract.
There are however individual terms of the contract which may survive even in cases of total avoidance. Arbitration, jurisdiction and choice-of-law clauses are considered to be different from the other terms of the contract and may be upheld notwithstanding the avoidance of the contract in whole or in part. Whether in fact such clauses remain operative is to be determined by the applicable domestic law.