Weight is the sole dividing line: fabrics weighing 170 g/m² or less fall under 5513, while those exceeding 170 g/m² go to 5514. Both headings require less than 85% synthetic staple fiber content mixed mainly with cotton, so the fiber and blend conditions alone do not determine which heading applies.

For unbleached or bleached polyester-cotton fabrics, the heading distinguishes plain weave (551311), 3- or 4-thread twill (551312), and other weaves (551313). For dyed fabrics, plain weave (551321) is separated from other weaves (551323). Yarn-dyed and printed subheadings are less granular by weave. Importers should confirm the weave construction to select the correct 6-digit subheading.