The lexicon of the top500 ( The Encyclopedia for Classification Codes ) explains the codes and definitions in the world of economical classifications.
NAICS Code 3271 Clay Product and Refractory Manufacturing
The NAICS Code 3271 is described as
Clay Product and Refractory Manufacturing It belongs to the code group
NAICS Code 327 Nonmetallic Mineral Product Manufacturing
To this Code "3271" belongs the sub codes
NAICS Code 32711: Pottery, Ceramics, and Plumbing Fixture Manufacturing (Pottery, Ceramics, and Plumbing Fixture Manufacturing)
NAICS Code 32712: Clay Building Material and Refractories Manufacturing (Clay Building Material and Refractories Manufacturing)