44 CFR §333.16

1. (a)The priority rating on a rated order may be changed or cancelled by:
   1. (1)An official action of FEMA; or
   2. (2)Written electronic notification from the person who placed the rated order (including a Delegate Agency).
2. (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.
3. (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 § 333.13.
4. (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 (prior to the start of production); or a change which is agreed upon between the supplier and the customer.
5. (e)A person must cancel any rated orders that the person (or a predecessor in interest) has placed with suppliers or cancel the priority ratings on those orders if the person no longer needs the items in those orders to fill a rated order.
6. (f)A person adding a rating to an unrated order, or changing or cancelling a priority rating must promptly provide written electronic notification to all suppliers to whom the order was sent of the addition, change, or cancellation.