5407.91 - Unbleached or bleached:

This HTS classification covers woven fabrics manufactured from synthetic filaments, excluding those specifically woven from materials of heading 5404. The fabrics within this category are characterized by their "unbleached or bleached" state, meaning they have undergone minimal or no coloring processes beyond their initial preparation. This includes fabrics that are in their natural state as spun from the filament yarn or have been treated with bleaching agents to achieve a white or off-white appearance, but have not yet been dyed, printed, or constructed from yarns of different colors.

It is crucial to distinguish this category from its siblings. Unlike 5407.92, which covers "dyed" fabrics, this heading specifically excludes any form of uniform coloring applied after weaving. Similarly, it differs from 5407.93 ("Of yarns of different colors"), which pertains to fabrics where the warp and weft yarns are inherently of contrasting colors, and from 5407.94 ("Printed"), which applies to fabrics featuring printed patterns. The defining characteristic here remains the absence of applied color or patterned designs beyond the inherent state of the unbleached or bleached filament yarn.

The subcategories within 5407.91 provide further refinement based on the presence of other fibers. The primary distinction often lies in whether the fabric is blended with wool or fine animal hair. If such a blend is present, it will fall under a more specific subheading. Otherwise, fabrics that are solely composed of synthetic filaments and meet the unbleached or bleached criteria, without any other coloring or printing, will be classified under "Other." This level of detail ensures accurate duty assessment based on the fabric's composition and processing.