Circumvention of anti dumping duty: new rules allow investigations and retrospective extension of duties to prevent evasion. The amendments create procedures for importers to seek determination of the actual margin of dumping where anti dumping duty paid is alleged to exceed that margin, obliging the designated authority to investigate, consider constructed export price adjustments and costs between importation and resale, and recommend refunds within prescribed timeframes. They also define and provide investigatory and remedial procedures for circumvention-including assembly, alteration of description or diversion of trade practices to evade duty-allowing initiation on application or suo motu, evidential requirements, time limits for investigation, public notice of findings, and possible retrospective extension of duties.