Ohio Rev. Code § 1302.05: Final written expression - parol or extrinsic evidence - UCC 2-202.

Terms with respect to which the confirmatory memoranda of the parties agree or which are otherwise set forth in a writing 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:

(A) by course of performance, course of dealing, or usage of trade as provided in section 1301.303 of the Revised Code; and

(B) by evidence of consistent additional terms unless the court finds the writing to have been intended also as a complete and exclusive statement of the terms of the agreement.