49 CFR 33.36 - Changes or cancellations of priority ratings and rated orders.
(a) The priority rating on a rated order may be changed or canceled by:
(1) An official action of the Department of Transportation; or
(b) If an unrated order is amended so as to make it a rated order, or a DO rating is changed to a DX rating, the supplier must give the appropriate preferential treatment to the order as of the date the change is received by the supplier.
(c) An amendment to a rated order that significantly alters a supplier's original production or delivery schedule shall constitute a new rated order as of the date of its receipt. The supplier must accept or reject the amended order according to the provisions of § 33.33.
(d) The following amendments do not constitute a new rated order: a change in shipping destination; a reduction in the total amount of the order; an increase in the total amount of the order which has negligible impact upon deliveries; a minor variation in size or design; or a change which is agreed upon between the supplier and the customer.
(f) When a priority rating is added to an unrated order, or is changed or canceled, all suppliers must be promptly notified in writing.