Section 59(1)(b) in The West Bengal Co-Operative Societies Act, 1983
(b)any debenture issued by any co-operative society without creating, declaring, assigning, limiting or extinguishing any right, title or interest to or in any immovable property except in so far as it entitled the holder of the debenture to the security afforded by a registered instrument whereby the co-operative society has mortgaged, conveyed or otherwise transferred the whole or part of its immovable property or interest therein to trustees upon trust for the benefit of the holder of the debenture; or