| 252 / | HD | COMPOSITIONS |
| 500 | DF | ELECTRICALLY CONDUCTIVE OR EMISSIVE COMPOSITIONS {6} |
| 518.1 | DF | .~ Metal compound containing {16} |
| 520.2 | DF | .~.~ Titanium or zirconium compound {2} |
| 520.22 | ![]() | .~.~.~ Boron, silicon, phosphorus, nitrogen, hydrogen, carbon, or halogen containing |