Section 3(4)(c) in National Housing Bank (Issue And Management Of Bonds) Regulations, 1989
(c)If a Bond has already been issued in the form of promissory note, the Bond holder desires of holding it in the form of an entry in an account with the National Housing Bank shall make requisition in Form II and surrender the Bond duly endorsed in favour of the National Housing Bank for the Bond being held in the form of an entry in an account to the books of the National Housing Bank.