4811.51 - Bleached, weighing more than 150 g/m²:

This HTS subheading, 4811.51, classifies paper and paperboard that has been bleached and weighs more than 150 grams per square meter. These materials may also be coated, impregnated, covered, surface-colored, surface-decorated, or printed. The key defining characteristics for this classification are the bleaching process and the significant weight per unit area, exceeding 150 g/m².

Distinguishing this category from its sibling, 4811.59 ("Other"), is crucial. While 4811.59 covers paper and paperboard meeting the general criteria of heading 4811 but not specifically fitting the specifications of other subheadings, 4811.51 is reserved for those instances where the material is specifically bleached and demonstrably weighs over 150 g/m². This precise weight threshold is a primary differentiating factor for classification within this subheading.

Within this category, further subdivisions exist based on the dimensions of the paper or paperboard when cut into strips or rolls. Subcategory 4811.51.60.00 specifically addresses items presented in strips or rolls with a width exceeding 15 cm, or in rectangular sheets where one side exceeds 36 cm and the other exceeds 15 cm when unfolded. This hierarchical structure allows for more granular classification based on the presentation and dimensions of the bleached, heavy-weight paper or paperboard.