New York Consolidated Laws, Uniform Commercial Code - UCC § 3-204. Special Indorsement;  Blank Indorsement

(1) A special indorsement specifies the person to whom or to whose order it makes the instrument payable.  Any instrument specially indorsed becomes payable to the order of the special indorsee and may be further negotiated only by his indorsement.

(2) An indorsement in blank specifies no particular indorsee and may consist of a mere signature.  An instrument payable to order and indorsed in blank becomes payable to bearer and may be negotiated by delivery alone until specially indorsed.

(3) The holder may convert a blank indorsement into a special indorsement by writing over the signature of the indorser in blank any contract consistent with the character of the indorsement.