The agreement so adopted shall be executed by an authorized person, provided that if the agreement is filed, it shall be executed and acknowledged in accordance with § 103 of this title. Any of the terms of the agreement of merger or consolidation may be made dependent upon facts ascertainable outside of such agreement, provided that the manner in which such facts shall operate upon the terms of the agreement is clearly and expressly set forth in the agreement of merger or consolidation. The term "facts," as used in the preceding sentence, includes, but is not limited to, the occurrence of any event, including a determination or action by any person or body, including the corporation.
8 Del. C. § 255