| 528 / | HD | SYNTHETIC RESINS OR NATURAL RUBBERS -- PART OF THE CLASS 520 SERIES | 
| * | DD | SYNTHETIC RESINS (Class 520, Subclass 1) {23} | 
| 373 | DF | .~ FROM SULFUR-CONTAINING REACTANT {5} | 
| 374 | DF | .~.~ From mercaptan or mercaptide-containing reactant {2} | 
| 376 |  | .~.~.~ With ethylenically unsaturated reactant |