PGI 213.302-3 Obtaining contractor acceptance and modifying purchase orders.
Generally, use unilateral modifications (see FAR 43.103) for—
(1) No-cost amended shipping instructions if—
(i) The amended shipping instructions modify a unilateral purchase order; and
(ii) The contractor agrees orally or in writing; and
(2) Any change made before work begins if—
(i) The change is within the scope of the original order;
(ii) The contractor agrees;
(iii) The modification references the contractor’s oral or written agreement; and
(iv) Block 13D of Standard Form 30, Amendment of Solicitation/Modification of Contract, is annotated to reflect the authority for issuance of the modification.