Species such as Pacific sanddab, windowpane flounder, or other commercially traded flatfish that lack a dedicated US tariff line typically land here. The key test is whether the species is named elsewhere in the HTS schedule — if it is, that specific line must be used instead. A binding ruling from CBP is advisable for any species where classification is genuinely uncertain.

NESOI lines attract more scrutiny because they are a common destination for misclassified goods. CBP may request species identification documentation or laboratory analysis to confirm that the product does not belong under a named provision. Maintaining scientific-name documentation from the foreign supplier is the most effective way to defend an NESOI classification.