Repeal of prior drawback rules ends their operation while preserving pending applications and claims under the old regime. Rule 20 repeals the earlier drawback rules on commencement while preserving that applications for determination or revision of drawback rates and claims for payment, in respect of goods exported before commencement but not disposed of before commencement, shall be disposed of under the prior rules; drawback amounts or rates determined under the prior rules cease to operate for goods exported on or after commencement.