This excerpt taken from the C 10-Q filed Aug 7, 2009.
10.6 No Waiver; Amendments. The rights which each Party has under this Agreement shall not be prejudiced or restricted by any indulgence or forbearance extended to the other Parties. No waiver by any Party in respect of any breach shall operate as a waiver in respect of any subsequent breach. No amendment, modification or discharge of this Agreement, and no waiver hereunder, shall be valid or binding unless set forth in writing and duly executed by the Party against whom enforcement of the amendment, modification, discharge or waiver is sought.