Which instrument is defined by section 6 of the Negotiable Instruments Act, 1881?

Section 6 of the Negotiable Instruments Act, 1881 defines a cheque as a bill of exchange drawn on a specified banker and not expressed to be payable otherwise than on demand, including the electronic image of a truncated cheque and a cheque in electronic form. The promissory note is defined in section 4, the bill of exchange in section 5 and the negotiable instrument in section 13.