Section 2--209. Modification, Rescission and Waiver.

(1) An agreement modifying a contract within this Article needs no
consideration to be binding.

(2) A signed agreement which excludes modification or rescission
except by a signed writing cannot be otherwise modified or rescinded,
but except as between merchants such a requirement on a form supplied by
the merchant must be separately signed by the other party.

(3) The requirements of the statute of frauds section of this Article
(Section 2--201) must be satisfied if the contract as modified is within
its provisions.

(4) Although an attempt at modification or rescission does not satisfy
the requirements of subsection (2) or (3) it can operate as a waiver.

(5) A party who has made a waiver affecting an executory portion of
the contract may retract the waiver by reasonable notification received
by the other party that strict performance will be required of any term
waived, unless the retraction would be unjust in view of a material
change of position in reliance on the waiver.