would be the extent of subject-matter of mortgage; the entire property forming the subject-matter of mortgage or a part thereof.” (emphasis supplied) 28. In the interest of completeness, we may note that the Bench of 2 learned Judges in Syndicate Bank (supra) had referred to a larger Bench, the question as to whether a property could be equitably mortgaged by deposit of documents other than the title deeds or registered title document. However, the 3-Judges Bench in Syndicate Bank v Estate Officer and Manager (Recoveries), Andhra Pradesh Industrial Infrastructure Corporation Limited, (2021) 3 SCC 736 was20 “of the opinion that the reference need not be answered in the peculiar facts and circumstances of the case since in our opinion the State of Andhra Pradesh and its successor viz. APIIC and Telangana Industrial Infrastructure Ltd., are estopped from challenging the validity of the mortgage.” In State of Haryana v Narvir Singh, (2014) 1 SCC 105, this Court observed: “11. A mortgage