The AUS-NZ Security Trustee’s failure or delay to exercise a power or right does not operate as a waiver of that power or right and the exercise of a power or right does not preclude either its exercise in the future or the exercise of any other power or right. A waiver is not effective unless it is in writing and waiver of a power or right is effective only in respect of the specific instance to which it relates and for the specific purpose for which it is given.