This excerpt taken from the LUX 6-K filed Nov 19, 2009.
No Waiver; Amendments, etc.
This letter sets out the full extent of your obligations of confidentiality owed to us in relation to the information the subject of this letter. No failure or delay in exercising any right, power or privilege under this letter will operate as a waiver thereof nor will any single or partial exercise of any right, power or privilege preclude any further exercise thereof or the exercise of any other right, power or privileges under this letter. The terms of this letter and your obligations under this letter may only be amended or modified by written agreement between us.