This Ag reement and the Executive Severance Agreement (together, the “Severance Agreements”) contain the entire agreement between the parties with respect to the right of Executive to receive severance compensation upon termination of his employment, and the Execu tive Employment Agreement, the Severance Agreements and the Proprietary Information and Inventions Agreement collectively represent the entire agreement and understanding between the parties as to the subject matter herein and supersede all prior or contem poraneous agreements, whether written or oral.   This Agreement may be modified only by agreement of the parties by a written instrument executed by the parties that is designated as an amendment to this Agreement.