Small scale industrial undertaking definition determines eligibility for investment allowance and initial depreciation under tax law. Clarifies that the monetary ceiling for a small scale industrial undertaking is the aggregate value of all plant and machinery installed as on the last day of the relevant previous year, excluding only tools, jigs, dies and moulds where the statute so provides; departmental or industry norms cannot exclude additional items like generating sets or transformers. The same approach applies to initial depreciation, subject to the distinct statutory definition for that allowance which does not exclude tools, jigs, dies and moulds.