49 CFR 33.55: Mandatory acceptance of an allocation order.

(a) Except as otherwise specified in this section, a person shall accept and comply with every allocation order received.

(b) A person shall not discriminate against an allocation order in any manner such as by charging higher prices for materials, services, or facilities covered by the order or by imposing terms and conditions for contracts and orders involving allocated materials, services, or facilities that differ from the person's terms and conditions for contracts and orders for the materials, services, or facilities prior to receiving the allocation order.

(c) If a person is unable to comply fully with the required action(s) specified in an allocation order, the person must notify the Department of Transportation immediately, explain the extent to which compliance is possible, and give the reasons why full compliance is not possible. If notification is given verbally, written or electronic confirmation must be provided within five (5) working days. Such notification does not release the person from complying with the order to the fullest extent possible, until the person is notified by the Department of Transportation that the order has been changed or cancelled.