| 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} |
| 99 | DF | .~.~ Cellular product formation prior to or during solid polymer formation in the presence of a stated ingredient other than water {18} |
| 103 | | .~.~.~ Ingredient contains a boron atom {2} |
| 104 | DF | .~.~.~.~> Boron trihalide or complex thereof |
| 105 | DF | .~.~.~.~> Boron atom is part of an organic compound |