After a Change Order has been agreed, if it is later found that there were errors in its preparation (incorrect exchange rate applied, for example) or impropriety on the part of the contractor in overstating the resources employed, or even discovering that the work the contractor is claiming as additional was in fact actually part of the contractor's responsibilities according to the original signed contract, can the Change Order be revised or rescinded? Of note, I am coming late to a contract that has not been managed well. Grant S. Murdie, MSc, CEng CEnv grant_s_murdie@hotmail.com