Section 49 of The Negotiable Instruments Act : Conversion of indorsement in blank into indorsement in full.
Conversion of indorsement in blank into indorsement in full. Negotiable Instruments Act 1881
The holder of a negotiable instrument indorsed in blank may, without signing his own name, by writing above the indorser’s signature a direction to pay to any other person as indorsee, convert the indorsement in blank into an indorsement in full; and the holder does not thereby incur the responsibility of an indorser.