Section 2-A-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 or by course of
             performance; 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.