Depreciation classification for plant and machinery: category-based rates and revised table determine allowable allowances. Depreciation for plant and machinery used in manufacturing safety razor blades must be allowed according to equipment category; for years up to 1969-70 category rates apply (machine tools, electrical machinery, general machinery) rather than a uniform rate, and for 1970-71 onward the revised Table under the Sixth Amendment Rules, 1969 prescribes special rates for specified items and a general rate for machinery without a special rate.