(1) Where, in any provision of sections 43 to 45, it is provided that the Principal Act shall have effect in its un-amended form, the provision shall be read as meaning that the Principal Act shall have effect as it had effect immediately before the relevant date (as defined in subsection (2) for the purposes of those sections).

(2) In sections 43 to 45 -

(a) a reference to a copy valuation certificate, under a particular section of the Principal Act, is a reference to a copy of a valuation certificate, provision for the issue of which is made by that section;

(b) a reference to a word or expression that is also used in the Principal Act shall be read in the manner in which it is to be read by virtue of the Principal Act;

(c) "application for revision" means an application for there to be exercised, in relation to a property, the powers conferred by section 28 of the Principal Act;

(d) "relevant date" means the date of commencement of the provision of this Act that amends the provisions of the Principal Act that are relevant to the steps taken in the cases mentioned in section 43, 44 or 45, as the case may be.