Title 11, Chapter 2, Section 202
Final written expression; parol or extrinsic evidence.
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 dealing or usage of trade (Code Section 11-1-205) or by course of performance (Code Section 11-2-208); 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.