Section 213.302-3 - Obtaining contractor acceptance and modifying purchase orders(1) Require written acceptance of purchase orders for classified acquisitions.(2) See PGI 213.302-3 for guidance on the use of unilateral modifications.(3) A supplemental agreement converts a unilateral purchase order to a bilateral agreement. If not previously included in the purchase order, incorporate the clause at 252.243-7001, Pricing of Contract Modifications, in the Standard Form 30, and obtain the contractor's acceptance by signature on the Standard Form 30.64 FR 2596, Jan. 15, 1999, as amended at 71 FR 3413, Jan. 23, 2006