Exemption availability: Circular permits exemption when power used only in raw-material manufacture; conversion-stage power defeats exemption. Whether the exemption in Notification No. 179/77-C.E., which requires no process ordinarily carried on with the aid of power, is negated when power is used in processing raw materials or components was examined. The Supreme Court treated powered processing of inputs performed outside the manufacturer's premises as part of manufacture, defeating the exemption where power was used in converting excisable inputs into finished goods. The Board reviewed Circular No. 10/85-CX.1 and concluded no modification was necessary, distinguishing power used in final conversion from power used only in antecedent raw-material manufacture.