The 600 mm threshold is a defined classification break in both SITC and the harmonized system. Products measured at exactly 600 mm or wider fall into the 'not under 600 mm' headings, while those below fall into the narrow-strip categories. Width is measured at the widest point of the coil or sheet, and even a few millimeters' difference can shift the applicable heading and potentially the duty rate or trade-remedy exposure.

Electrolytic (electroplated) coatings are deposited using an electric current in a chemical bath, producing thin, uniform layers — common in electrogalvanized or tin-plated steel. Non-electrolytic coatings include hot-dip galvanizing, aluminizing, and mechanical or chemical deposition methods. The process distinction is explicitly built into the SITC structure, so importers need mill documentation confirming the coating method to classify correctly.