In Venkata Reddy v. Pethi Reddy, AIR 1963 SC 992, reversing a decision of the Madras High Court in AIR 1956 Mad 413, Mudholkar, J. said (at p. 995) :

“A decision is said to be final when, so far as the Court rendering it is concerned, it is unalterable except by resort to such provisions of the Code of Civil Procedure as permit its reversal, modification or amendment. Similarly, a final decision would mean a decision which would operate as res judicata between the parties if it is not sought to be modified or reversed by preferring an appeal or a revision or a review application as is permitted by the Code. A preliminary decree passed, whether it is in a mortgage suit or a partition suit, is not a tentative decree but must, insofar as the matters dealt with by it are concerned, be regarded as conclusive. No doubt, in suits which contemplate the making of two decrees — a preliminary decree and a final decree — the decree which would be executable would be the final decree: But the finality of a decree or a decision does not necessarily depend upon its being executable. The Legislature in its wisdom has thought that suits of certain types should be decided in stages and though the suit in such cases can be regarded as fully and completely decided only after a final decree is made, the decision of the Court arrived at the earlier stage also has a finality attached to it. Section 97, C.P.C. clearly indicates that as to the matters covered by it, a preliminary decree is regarded as embodying the final decision of the Court passing that decree.”