Section 3--407. Alteration.

(1) Any alteration of an instrument is material which changes the
contract of any party thereto in any respect, including any such change
in

(a) the number or relations of the parties; or

(b) an incomplete instrument, by completing it otherwise than as

authorized; or

(c) the writing as signed, by adding to it or by removing any

part of it.

(2) As against any person other than a subsequent holder in due course

(a) alteration by the holder which is both fraudulent and

material discharges any party whose contract is thereby

changed unless that party assents or is precluded from

asserting the defense;

(b) no other alteration discharges any party and the instrument

may be enforced according to its original tenor, or as to

incomplete instruments according to the authority given.

(3) A subsequent holder in due course may in all cases enforce the
instrument according to its original tenor, and when an incomplete
instrument has been completed, he may enforce it as completed.