44 CFR 333.53: Letters and memoranda of understanding.

(a) A letter or memorandum of understanding is an official action, which may be issued electronically, to resolve special priorities assistance cases to reflect an agreement reached by all parties (FEMA, the Department of Commerce (if applicable), a Delegate Agency (if applicable), the supplier, and the customer).

(b) A letter or memorandum of understanding is not used to alter scheduling between rated orders, to authorize the use of priority ratings, to impose restrictions under this part, or to take other official actions. Rather, letters or memoranda of understanding are used to confirm production or shipping schedules which do not require modifications to other rated orders.