28. (1) Save as in this Part otherwise provided, every document mentioned in section 17, sub-section (1), clause (a), (b), (c), (d) and (e), section 17, sub-section (2), and section 18, in so far as such documents affects immoveable property shall be presented for registration in the office of a Sub-Registrar within whose sub-district the whole or ¹[major portion] of the property to which such document relates is situate ²[: Provided that where the major portion of such property is not situate within one sub-district the document shall be presented for registration in the office of the Sub-Registrar within whose sub-district any portion of such property is situate.] (2) Notwithstanding anything contained in sub-section (1),- (a) after a document is registered, no party thereto shall be entitled to question the validity of its registration on the ground that the property which purported to give jurisdiction to the Sub-Registrar to register it either did not exist or was fictitious or insignificant or was not intended to be conveyed; and (b) a document the registration of which is secured by the inclusion of a non-existent, fictitious or insignificant portion or item shall not in any manner affect the rights of a person who was not a party thereto and acquired rights in the property without notice of the transaction to which such document relates.