"If after the Effective Date of this Agreement, ABC Company (LICENSOR) grants to any other third party, a patent license which is substantially the same scope as granted to XYZ Company (LICENSEE) herein but under more favorable royalty rates than those given to XYZ Company under this Agreement, ABC Company shall promptly notify XYZ Company of said more favorable royalty rates, and XYZ Company shall have the right and option to substitute such more favorable royalty rates for the royalty rates contained in this Agreement..." The above clause is generally referred to as: