GST classification for turpentine and terpenic oils determines the applicable tax rate under Schedule 3 for those goods. Goods under tariff item 3805-gum, wood or sulphate turpentine and other terpenic oils from coniferous woods, including crude dipentene, sulphite turpentine, crude para-cymene and pine oil with alpha-terpineol-are classified under Schedule 3 and subject to GST at 18% until 21-09-2025, defining the taxable scope and applicable rate for those products during the specified period.