The U.S. Customs and Border Protection (CBP) has determined that ISO 20871 would be used to assess the characteristics of textile material attached to outer soles.
Some issues regarding this is the questioning of how to classify footwear if the outer soles are made of 50-percent textile materials. The original ruling as identified by the CBP is to identify that footwear as other footwear under heading 6405.
The standard also recognizes that if textile material is applied to an otherwise rubber or plastic sole and it is still present after at least one of the three required samples.