Non supply of goods sent abroad for exhibition is not zero rated; invoicing and refunds arise only on sale or deemed supply. Removal of goods for exhibition or consignment abroad is not a supply absent consideration or Schedule I applicability, and therefore not a zero-rated supply. Such removals qualify as sale on approval and must be accompanied by a delivery challan; no bond or LUT is required. A tax invoice is to be issued when goods are sold abroad or, if neither sold nor returned within the stipulated period, on the date the supply is deemed to occur. Refund of input tax credit for zero-rated supply is available only after the invoice is issued in accordance with the rules.