Amendments, variations, modifications or changes herein may be made effective and binding upon the parties by, and only by, the setting forth of same in a document duly executed by the General Partner and the Advisor Sub (provided, that any amendments, variations, modifications or changes to Section 1 or to the third sentence of Section 3 shall only be effective and binding upon the parties if also duly executed by the Advisor), and any alleged amendment, variation, modification or change herein which is not so documented shall not be effective as to any party.