How GRI 1–6 actually works.

Classification starts and, most of the time, ends here. You read the heading text and the legal notes for that section and chapter — not the descriptive titles, which are for reference only — and find the heading that names the good. If a heading or note already settles it, you stop. Rules 2–6 only matter when GRI 1 doesn't.

2(a) extends a heading for a finished article to cover that same article incomplete or unfinished, as long as it has the essential character of the finished good — and to unassembled or disassembled goods presented together. 2(b) extends a heading for a material or substance to cover that material mixed or combined with other materials, which is what pulls a mixed good into GRI 3.

Applied in order, stopping at the first one that resolves it. 3(a): the most specific heading beats a general one. 3(b): if specificity doesn't decide it, classify by whichever material or component gives the good its essential character. 3(c): if that's still a tie, use the heading that comes last in numerical order.

Rarely invoked. Classify under the heading for the goods to which the item is "most akin." If you're reaching for GRI 4, that's usually a sign to re-check GRI 1 and 3 first — most goods that look unclassifiable have a heading once you read the chapter notes closely.

5(a): cases and containers specially shaped or fitted for a specific article, of a kind normally sold with it, are classified with that article. 5(b): packing materials and containers presented with goods are classified with those goods unless the packing is clearly suitable for repetitive use — a reusable steel drum, for example, is classified on its own.

Rules 1–5 apply again, mutatis mutandis, to choose between subheadings within an already-selected heading — but only subheadings at the same level are compared against each other. This is where most of the real classification work happens below the 4-digit heading, down through the 6-digit and 8/10-digit levels.