Blue denim is specifically a yarn-dyed fabric woven with blue-dyed warp yarns and undyed (white or natural) filling yarns in a twill construction. Non-blue denim (5516430015) covers the same twill-warp construction but with warp yarns dyed in colors other than blue. The color of the warp yarn — not the finished fabric appearance — is the determinative factor, and mill documentation confirming yarn color before weaving supports the correct line.

The US schedule lists jacquard weaves (5516430020) and denim lines (5516430010 and 5516430015) as separate provisions. Where a fabric could arguably fit both, the more specific description — denim, defined by its twill construction and yarn-dyeing method — generally controls over the broader jacquard weave provision. A licensed customs broker should review the fabric's technical specifications to determine the correct 10-digit line.