Section 61(2)(iv) in The West Bengal Correctional Services Act, 1992
(iv)when the provisions of clause (i) or clause (ii) or clause (iii) do not apply to a prisoner who is about to complete a period of 20 years of continuous detention including the period of release on parole and the period of remission, if any, earned or granted to him, and has to his credit a satisfactory record during the last 3 years of detention.