Securities valuation rules: stock-in-trade measured at lower of actual cost or net realisable value with categorywise comparison. ICDS VIII governs securities for computing income under business or other sources. Part A treats securities held as stock-in-trade: acquisition is recognised at actual cost (including acquisition charges), exchanges are measured at fair value as cost, and unpaid pre-acquisition interest is deducted from cost. At each year end such securities are valued at the lower of initial cost and net realisable value on a categorywise basis; unlisted or irregularly quoted securities remain at actual cost. Where specific identification is not possible, cost is determined by FIFO or weighted average. Part B requires scheduled banks and certain public financial institutions to follow RBI guidelines for classification, recognition and measurement.