Semichemical fluting is produced by a semi-chemical pulping process that yields a stiff, high-flat-crush medium widely used in corrugated box manufacturing. Straw fluting (480512) uses agricultural fiber rather than wood pulp. The NESOI subheading (480519) captures corrugating medium made by other processes, such as recycled-fiber or fully chemical processes, that do not meet the semichemical or straw definitions.

Note 2 to Chapter 48 specifies the maximum degree of processing that paper and paperboard may undergo and still be classified in the chapter's base-paper headings. If a paper has been further worked — for example, coated, impregnated, or converted — beyond what Note 2 permits, it moves to a different heading. For goods near the boundary, reviewing the note text and, if necessary, seeking a CBP binding ruling is advisable.