There is no single universally codified brightness cutoff in the HTS text itself; the distinction follows industry convention, where fully bleached pulp typically achieves ISO brightness of 88% or above, while semibleached pulp falls in a lower intermediate range. Importers should retain mill certificates stating the brightness specification and bleaching sequence to support the correct 10-digit line selection between 4703210020 and 4703210040.

Bleached softwood kraft (BSKP) provides long, strong fibers that add tear and tensile strength to a paper furnish, while bleached hardwood kraft (BHKP, classified under heading 470329) contributes shorter fibers that improve formation, smoothness, and printability. Most printing and writing paper grades use a blend of both; understanding which pulp type is being imported is essential for both classification accuracy and procurement planning.