D.C. Mun. Regs. tit. 19, § 4311
4311.1 A purchase order may be modified by using a form approved by the CCO. Each purchase order modification shall identify the order it modifies and shall contain an appropriate modification number.
4311.2 The CCO may obtain a contractor's written acceptance of a purchase order modification if the written acceptance is determined by the CCO to be necessary to ensure the contractor's compliance and acceptance of the purchase order as modified.
SOURCE: Final Rulemaking published at 55 DCR 493 (January 18, 2008).