Customs duty amendment revises exemptions and effective duty rates for specified medical devices, optical and tunnelling machinery. Amendment to Notification No. 21/2002 modifies exemption and effective duty rates by substituting entries for S. Nos. 202 and 436, inserting S. No. 363A for ostomy products, replacing S. No. 598 to list tunnel boring machines and parts with Nil basic/additional duty treatment, inserting S. No. 604 for goods used in manufacture of optical disk drives (naming specific components), and adding pharmaceuticals and radiographic agents as items 160-170 in Annexure List 3.