Section 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.