2006 New York Code - Incomplete Instruments.

 
  Section 3--115. Incomplete Instruments.
    (1) When a paper whose contents at the time of signing show that it is
  intended to become an instrument is signed while still incomplete in any
  necessary  respect it cannot be enforced until completed, but when it is
  completed  in  accordance  with  authority  given  it  is  effective  as
  completed.
    (2)  If  the  completion  is  unauthorized  the  rules  as to material
  alteration apply  (Section  3--407),  even  though  the  paper  was  not
  delivered  by  the  maker or drawer; but the burden of establishing that
  any completion is unauthorized is on the party so asserting.