JUDGMENT

VENKATACHALIAH, C.J.I. - In these appeals and special leave petitions brought up by the Revenue the short but interesting question that arises is whether Rule 1-BB of the Wealth Tax Rules, 1957 is a provision which affects and alters the substantive rights or is merely procedural. The further sequential and cognate question is whether the Rule is attracted to all proceedings pending at its enactment. The said Rule 1-BB concerns the mode of valuation of house-property wholly or mainly used for residential purposes, for the purposes of ascertaining the net wealth under the Wealth Tax Act, 1957.

2. Section 3 of the Wealth Tax Act is the charging section. It seeks to bring to charge for every assessment year the net wealth on the corresponding valuation date of every individual, Hindu undivided family and company. The expression "net wealth" is defined in Section 2(m) of the Act. Section 2(q) defines the "valuation date". Section 4 enumerates the assets to be included in computing net wealth. Sections 5 and 6 exempt certain assets in India an outside from being included in computing the net wealth.

3. Section 7 - and this provision is of particular relevance here - speaks as t