48 CFR § 1.702 - General.

(a) A D&F shall ordinarily be for an individual contract action. Unless otherwise prohibited, class D&F's may be executed for classes of contract action (see 1.703). The approval granted by a D&F is restricted to the proposed contract action(s) reasonably described in that D&F. D&F's may provided for a reasonable degree of flexibility. Furthermore, in their application, reasonable variations in estimated quantities or prices are permitted, unless the D&F specifies otherwise.

(b) When an option is anticipated, the D&F shall state the approximate quantity to be awarded initially and the extent of the increase to be permitted by the option.