5309.21 - Unbleached or bleached:

This HTS category, 5309.21, specifically classifies unbleached or bleached woven fabrics of flax that contain less than 85 percent by weight of flax, and critically, are not further specified in subcategories for higher wool or fine animal hair content. The "unbleached or bleached" designation indicates the finishing state of the fabric, distinguishing it from fabrics that might be dyed, printed, or otherwise decorated.

Within the broader context of woven flax fabrics containing less than 85 percent flax, this subcategory 5309.21 serves as a default for those not falling into the "Other" category (5309.29) which typically covers fabrics with different finishing treatments or compositions not explicitly detailed. Therefore, the primary classification driver here is the flax content combined with the unbleached or bleached state.

The subcategories under 5309.21 further refine this classification based on the presence of other textile materials. For instance, 5309.21.20.00 is designated for fabrics containing a significant proportion of wool or fine animal hair, specifically over 17 percent by weight. This highlights the importance of precise material composition analysis when classifying these types of woven fabrics. The subsequent "Other" subcategory would encompass fabrics that meet the initial criteria of 5309.21 but do not meet the specific composition threshold for wool or fine animal hair.