Which section of Patents Act, 1970 deals with burden of proof in case of suits concerning infringement?

Section 104A. Burden of proof in case of suits concerning infringement (1) In any suit for infringement of a patent, where the subject matter of patent is a process for obtaining a product, the court may direct the defendant to prove that the process used by him to obtain the product, identical to the product of the patented process, is different from the patented process if,—             (a)the subject matter of the patent is a process for obtaining a new product; or             (b)there is a substantial likelihood that the identical product is made by the process, and the patentee or a person deriving title or interest in the patent from him, has been unable through reasonable efforts to determine the process actually used: Provided that the patentee or a person deriving title or interest in the patent from him first proves that the product is identical to the product directly obtained by the patented process.