Section 17(4C)(b) in The Reserve Bank of India Act, 1934
(b)repayable on the expiry of fixed periods not exceeding eighteen months from the date of such loan or advance, against securities of the Central Government or of any State Government, of any maturity, or against bonds and debentures issued by the corporation to which the loan or advance is made, and guaranteed by the Central or a State Government, and maturing within a period not exceeding eighteen months from the date of such loan or advance: