| 521 / | HD | SYNTHETIC RESINS OR NATURAL RUBBERS -- PART OF THE CLASS 520 SERIES |
| * | DD | SYNTHETIC RESINS (Class 520, Subclass 1) {3} |
| 50 | DF | .~ CELLULAR PRODUCTS OR PROCESSES OF PREPARING A CELLULAR PRODUCT, E.G., FOAMS, PORES, CHANNELS, ETC. {27} |
| 178 | DF | .~.~ Cellular product derived from a reactant containing two or more three membered heterocyclic rings wherein two of the ring members are carbon atoms and the remaining ring member is a chalcogen atom {1} |
| 179 | | .~.~.~ With -C(=X)-X containing reactant wherein X is a chalcogen atom |