Provisional assessment in anti-circumvention investigations enabled with importer guarantees; investigation periods and review timelines tightened. Amendments limit initiation to investigations not more than six months old and set normal inquiry duration at twelve months, permitting a recorded discretion for shorter or longer periods; they replace 'Collector of Customs' with 'Principal Commissioner of Customs or Commissioner of Customs,' omit an explanation in rule 22, require reviews to be completed at least three months before duty expiry and make specified rules applicable mutatis mutandis to reviews; and authorize provisional assessment of imports alleged to circumvent an antidumping duty with a power to demand importer guarantees pending final decision.