Which of the following does not form the part of a Negotiable Instrument as per Negotiable Instruments Act, 1881?

A negotiable instrument is a commercial document in writing that contains an order for payment of money either on demand or after a certain time. There are of three types of Negotiable Instrument as per Negotiable Instruments Act, 1881:        I.        Bills of exchange      II.        Promissory notes     III.        Cheques Currency is a legal tender, guaranteed by the government to transfer value but the Negotiable Instruments have following characteristics. ·         It is written document signed and stamped by the maker/drawer. ·         It has a specific payee to whom the value is transferable. ·         Negotiable Instruments requires acceptance and endorsement.