10 CFR 217.53: Types of allocation orders.

There are three types of allocation orders available for communicating allocation actions. These are:

(a) Set-aside: an official action that requires a person to reserve materials, services, or facilities capacity in anticipation of the receipt of rated orders;

(b) Directive: an official action that requires a person to take or refrain from taking certain actions in accordance with its provisions. For example, a directive can require a person to: stop or reduce production of an item; prohibit the use of selected materials, services, or facilities; or divert the use of materials, services, or facilities from one purpose to another; and

(c) Allotment: an official action that specifies the maximum quantity of a material, service, or facility authorized for a specific use.