Section 17
Ambiguous instruments
Chapter 2: Of notes, bills and cheques
Where an instrument may be construed either as a promissory note or bill of exchange, the holder may at his election treat it as either, and the instrument shall be thenceforward treated accordingly.
The Negotiable Instruments Act, 1881 (Act No. 26 of 1881). From the updated text on India Code, with later amendments. Being checked against the official copy; amendment notes are not shown yet.