Section 1--205. Course of Dealing and Usage of Trade

(1)  A course of dealing is a sequence of previous conduct between the
  parties to a particular transaction which is fairly to  be  regarded  as
  establishing  a  common  basis  of  understanding for interpreting their
  expressions and other conduct.
    (2) A usage of trade is any practice or method of dealing having  such
  regularity  of observance in a place, vocation or trade as to justify an
  expectation that it will be observed with respect to the transaction  in
  question.  The  existence  and scope of such a usage are to be proved as
  facts. If it is established that such a usage is embodied in  a  written
  trade  code  or similar writing the interpretation of the writing is for
  the court.
    (3) A course of dealing between parties and any usage of trade in  the
  vocation  or  trade  in  which  they are engaged or of which they are or
  should be aware give particular meaning to  and  supplement  or  qualify
  terms of an agreement.
    (4)  The  express  terms  of  an agreement and an applicable course of
  dealing or usage of trade shall  be  construed  wherever  reasonable  as
  consistent  with  each other; but when such construction is unreasonable
  express terms control both course of dealing  and  usage  of  trade  and
  course of dealing controls usage of trade.
    (5)  An  applicable  usage  of  trade  in  the place where any part of
  performance is to occur shall be used in interpreting the  agreement  as
  to that part of the performance.
    (6)  Evidence of a relevant usage of trade offered by one party is not
  admissible unless and until he has given the other party such notice  as
  the court finds sufficient to prevent unfair surprise to the latter.