N.D. Cent. Code § 41-02-09

Terms with respect to which the confirmatory memoranda of the parties agree or which are otherwise set forth in a record intended by the parties as a final expression of their agreement with respect to such terms as are included therein may not be contradicted by evidence of any prior agreement or of a contemporaneous oral agreement but may be explained or supplemented: 1. By course of performance, course of dealing, or usage of trade (section 41-01-17); and 2. By evidence of consistent additional terms unless the court finds the record to have been intended also as a complete and exclusive statement of the terms of the agreement.

41-02-10. (2-203) Seals inoperative. The affixing of a seal to a record evidencing a contract for sale or an offer to buy or sell goods does not constitute the record a sealed instrument and the law with respect to sealed instruments does not apply to such a contract or offer.