Indiana Code Title 26. Commercial Law § 26-1-1-205

Sec. 205. (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 course of performance is a sequence of conduct between the parties to a particular transaction that exists if the:

(3) 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.

(4) A course of dealing or course of performance 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.

(5) Except as provided in subsection (8), the express terms of an agreement and an applicable course of dealing, course of performance, or usage of trade shall be construed wherever reasonable as consistent with each other.  If such a construction is unreasonable:

(6) 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.

(7) Evidence of a relevant usage of trade offered by one party is not admissible unless and until the party has given the other party such notice as the court finds sufficient to prevent unfair surprise to the latter.

(8) Subject to IC 26-1-2-209, a course of performance is relevant to show a waiver or modification of any term inconsistent with the course of performance.